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Sample records for food recalls web

  1. Associations between reported intakes of carotenoid-rich foods and concentrations of carotenoids in plasma: a validation study of a web-based food recall for children and adolescents.

    Science.gov (United States)

    Medin, Anine Christine; Carlsen, Monica Hauger; Andersen, Lene Frost

    2016-12-01

    To validate estimated intakes of carotenoid-rich foods from a web-based food recall (WebFR) using carotenoids in blood as an objective reference method. Cross-sectional validation study using carotenoids in plasma to evaluate estimated intakes of selected carotenoid-rich foods. Participants recorded their food intake in the WebFR and plasma concentrations of β-carotene, α-carotene, β-cryptoxanthin, lycopene, lutein and zeaxanthin were measured. Schools and homes of families in a suburb of the capital of Norway. A total of 261 participants in the age groups 8-9 and 12-14 years. Spearman's rank correlation coefficients ranged from 0·30 to 0·44, and cross-classification showed that 71·6-76·6 % of the participants were correctly classified, when comparing the reported intakes of carotenoid-rich foods and concentrations of the corresponding carotenoids in plasma, not including lutein and zeaxanthin. Correlations were acceptable and cross-classification analyses demonstrated that the WebFR was able to rank participants according to their reported intake of foods rich in α-carotene, β-carotene, β-cryptoxanthin and lycopene. The WebFR is a promising tool for dietary assessment among children and adolescents.

  2. Web-based Food Behaviour Questionnaire: validation with grades six to eight students.

    Science.gov (United States)

    Hanning, Rhona M; Royall, Dawna; Toews, Jenn E; Blashill, Lindsay; Wegener, Jessica; Driezen, Pete

    2009-01-01

    The web-based Food Behaviour Questionnaire (FBQ) includes a 24-hour diet recall, a food frequency questionnaire, and questions addressing knowledge, attitudes, intentions, and food-related behaviours. The survey has been revised since it was developed and initially validated. The current study was designed to obtain qualitative feedback and to validate the FBQ diet recall. "Think aloud" techniques were used in cognitive interviews with dietitian experts (n=11) and grade six students (n=21). Multi-ethnic students (n=201) in grades six to eight at urban southern Ontario schools completed the FBQ and, subsequently, one-on-one diet recall interviews with trained dietitians. Food group and nutrient intakes were compared. Users provided positive feedback on the FBQ. Suggestions included adding more foods, more photos for portion estimation, and online student feedback. Energy and nutrient intakes were positively correlated between FBQ and dietitian interviews, overall and by gender and grade (all p<0.001). Intraclass correlation coefficients were ≥0.5 for energy and macro-nutrients, although the web-based survey underestimated energy (10.5%) and carbohydrate (-15.6%) intakes (p<0.05). Under-estimation of rice and pasta portions on the web accounted for 50% of this discrepancy. The FBQ is valid, relative to 24-hour recall interviews, for dietary assessment in diverse populations of Ontario children in grades six to eight.

  3. ASA24 enables multiple automatically coded self-administered 24-hour recalls and food records

    Science.gov (United States)

    A freely available web-based tool for epidemiologic, interventional, behavioral, or clinical research from NCI that enables multiple automatically coded self-administered 24-hour recalls and food records.

  4. Validity of a multipass, web-based, 24-hour self-administered recall for assessment of total energy intake in blacks and whites.

    Science.gov (United States)

    Arab, Lenore; Tseng, Chi-Hong; Ang, Alfonso; Jardack, Patricia

    2011-12-01

    To date, Web-based 24-hour recalls have not been validated using objective biomarkers. From 2006 to 2009, the validity of 6 Web-based DietDay 24-hour recalls was tested among 115 black and 118 white healthy adults from Los Angeles, California, by using the doubly labeled water method, and the results were compared with the results of the Diet History Questionnaire, a food frequency questionnaire developed by the National Cancer Institute. The authors performed repeated measurements in a subset of 53 subjects approximately 6 months later to estimate the stability of the doubly labeled water measurement. The attenuation factors for the DietDay recall were 0.30 for blacks and 0.26 for whites. For the Diet History Questionnaire, the attenuation factors were 0.15 and 0.17 for blacks and whites, respectively. Adjusted correlations between true energy intake and the recalls were 0.50 and 0.47 for blacks and whites, respectively, for the DietDay recall. For the Diet History Questionnaire, they were 0.34 and 0.36 for blacks and whites, respectively. The rate of underreporting of more than 30% of calories was lower with the recalls than with the questionnaire (25% and 41% vs. 34% and 52% for blacks and whites, respectively). These findings suggest that Web-based DietDay dietary recalls offer an inexpensive and widely accessible dietary assessment alternative, the validity of which is equally strong among black and white adults. The validity of the Web-administered recall was superior to that of the paper food frequency questionnaire.

  5. MANAGEMENT OF UNSAFE FOOD RECALL

    Directory of Open Access Journals (Sweden)

    Justyna Górna

    2016-06-01

    Full Text Available The aim of this paper is to present the essence of eff ective management to recall unsafe food. The implementation of the development is refl ected in its individual parts. Legal requirements oblige companies to take immediate action when an available product poses a threat to the consumer’s health or life. These actions imply blocking of a suspicious batch or a possible product recall, as well as eff ective communication with supervisory authorities and consumers, if a product has already been available to them. The scope of these regulations is scrupulously listed in private safety standards and food quality, such as BRC, IFS, or in an international norm ISO 22000. The article emphasized the importance of the traceability system to ensure eff ective recall, also analysed the results of the research into the causes and evaluated the eff ectiveness of the food recall.

  6. Development of a Web-Based 24-h Dietary Recall for a French-Canadian Population

    Science.gov (United States)

    Jacques, Simon; Lemieux, Simone; Lamarche, Benoît; Laramée, Catherine; Corneau, Louise; Lapointe, Annie; Tessier-Grenier, Maude; Robitaille, Julie

    2016-01-01

    Twenty-four-hour dietary recalls can provide high-quality dietary intake data, but are considered expensive, as they rely on trained professionals for both their administration and coding. The objective of this study was to develop an automated, self-administered web-based 24-h recall (R24W) for a French-Canadian population. The development of R24W was inspired by the United States Department of Agriculture (USDA) Automated Multiple-Pass Method. Questions about the context of meals/snacks were included. Toppings, sauces and spices frequently added to each food/dish were suggested systematically. A list of frequently forgotten food was also suggested. An interactive summary allows the respondent to track the progress of the questionnaire and to modify or remove food as needed. The R24W prototype was pre-tested for usability and functionality in a convenience sample of 29 subjects between the ages of 23 and 65 years, who had to complete one recall, as well as a satisfaction questionnaire. R24W includes a list of 2865 food items, distributed into 16 categories and 98 subcategories. A total of 687 recipes were created for mixed dishes, including 336 ethnic recipes. Pictures of food items illustrate up to eight servings per food item. The pre-test demonstrated that R24W is easy to complete and to understand. This new dietary assessment tool is a simple and inexpensive tool that will facilitate diet assessment of individuals in large-scale studies, but validation studies are needed prior to the utilization of the R24W. PMID:27854276

  7. Development of a Web-Based 24-h Dietary Recall for a French-Canadian Population

    Directory of Open Access Journals (Sweden)

    Simon Jacques

    2016-11-01

    Full Text Available Twenty-four-hour dietary recalls can provide high-quality dietary intake data, but are considered expensive, as they rely on trained professionals for both their administration and coding. The objective of this study was to develop an automated, self-administered web-based 24-h recall (R24W for a French-Canadian population. The development of R24W was inspired by the United States Department of Agriculture (USDA Automated Multiple-Pass Method. Questions about the context of meals/snacks were included. Toppings, sauces and spices frequently added to each food/dish were suggested systematically. A list of frequently forgotten food was also suggested. An interactive summary allows the respondent to track the progress of the questionnaire and to modify or remove food as needed. The R24W prototype was pre-tested for usability and functionality in a convenience sample of 29 subjects between the ages of 23 and 65 years, who had to complete one recall, as well as a satisfaction questionnaire. R24W includes a list of 2865 food items, distributed into 16 categories and 98 subcategories. A total of 687 recipes were created for mixed dishes, including 336 ethnic recipes. Pictures of food items illustrate up to eight servings per food item. The pre-test demonstrated that R24W is easy to complete and to understand. This new dietary assessment tool is a simple and inexpensive tool that will facilitate diet assessment of individuals in large-scale studies, but validation studies are needed prior to the utilization of the R24W.

  8. Recalls of Food and Dietary Supplements

    Data.gov (United States)

    U.S. Department of Health & Human Services — Food producers recall their products from the marketplace when the products are mislabeled or when the food may present a health hazard to consumers because the food...

  9. A comparative analysis of national food recall systems

    Directory of Open Access Journals (Sweden)

    Gaetano Liuzzo

    2013-12-01

    Full Text Available Food recall and withdrawal is a fundamental tool for risk management and different countries stated the mandatory application of a system for food; the present work is an analysis of different systems applied in different countries. The main objective of analysed systems is the consumer’s health protection through an audit system and the application of system to rapidly recall/withdraw food on the part of producers. The comparative analysis of different national systems [i.e. European Union (EU, Australia, Canada, US and China] shows differences both of the terminological and legal aspects; the words recall and withdrawal have different meaning in EU legislation than in other counties’ legislations; from a legal point of view, two main recall/withdrawal systems could be identified: a mandatory one (EU and China and a voluntary one (USA, Canada and Australia; all the investigated systems have a co-operative approach between authority and food business operator, but different functions on their respective roles could be identified.

  10. Analysis of U.S. Food and Drug Administration food allergen recalls after implementation of the food allergen labeling and consumer protection act.

    Science.gov (United States)

    Gendel, Steven M; Zhu, Jianmei

    2013-11-01

    To avoid potentially life-threatening reactions, food allergic consumers rely on information on food labels to help them avoid exposure to a food or ingredient that could trigger a reaction. To help consumers in the United States obtain the information that they need, the Food Allergen Labeling and Consumer Protection Act of 2004 defined a major food allergen as being one of eight foods or food groups and any ingredient that contains protein from one of these foods or food groups. A food that contains an undeclared major food allergen is misbranded under the U.S. Food, Drug, and Cosmetic Act and is subject to recall. Food allergen labeling problems are the most common cause of recalls for U.S. Food and Drug Administration (FDA)-regulated food products. To help understand why food allergen recalls continue to occur at a high rate, information on each food allergen recall that occurred in fiscal years 2007 through 2012 was obtained from the FDA recall database. This information was analyzed to identify the food, allergen, root cause, and mode of discovery for each food allergen recall. Bakery products were the most frequently recalled food type, and milk was the most frequently undeclared major food allergen. Use of the wrong package or label was the most frequent problem leading to food allergen recalls. These data are the first reported that indicate the importance of label and package controls as public health measures.

  11. Children's recall of fast food television advertising-testing the adequacy of food marketing regulation.

    Directory of Open Access Journals (Sweden)

    Amy M Bernhardt

    Full Text Available In the United States, the fast food companies McDonald's and Burger King participate in marketing self-regulation programs that aim to limit emphasis on premiums and promote emphasis of healthy food choices. We determine what children recall from fast food television advertisements aired by these companies.One hundred children aged 3-7 years were shown McDonald's and Burger King children's (MDC & BKC and adult (MDA & BKA meal ads, randomly drawn from ads that aired on national US television from 2010-11. Immediately after seeing the ad, children were asked to recall what they had seen and transcripts evaluated for descriptors of food, healthy food (apples or milk, and premiums/tie-ins.Premiums/tie-ins were common in children's but rarely appeared in adult ads, and all children's ads contained images of healthy foods (apples and milk. Participants were significantly less likely to recall any food after viewing the children's vs. the adult ad (MDC 32% [95% confidence interval 23, 41] vs. MDA 68% [59, 77] p <0.001; BKC 46% [39, 56] vs. BKA 67% [58, 76] respectively, p = 0.002. For children's ads alone and for both restaurants, recall frequency for all food was not significantly different from premium/tie-ins, and participants were significantly more likely to recall other food items than apples or milk. Moreover, premiums/tie-ins were recalled much more frequently than healthy food (MDC 45% [35, 55] vs. 9% [3, 15] p<0.001; BKC 54% [44, 64] vs. 2% [0, 5] respectively, p<0.001.Children's net impressions of television fast food advertising indicate that industry self-regulation failed to achieve a de-emphasis on toy premiums and tie-ins and did not adequately communicate healthy menu choices. The methods devised for this study could be used to monitor and better regulate advertising patterns of practice.

  12. Food Recall Attitudes and Behaviors of School Nutrition Directors

    Science.gov (United States)

    Grisamore, Amber; Roberts, Kevin R.

    2014-01-01

    Purpose/Objectives: The purpose of this study was to explore school nutrition directors' attitudes and behaviors about food recalls. Specific objectives included: 1) Determine current food recall attitudes and the relationship between demographics and these attitudes; 2) Determine current practices of school nutrition directors related to…

  13. Evaluation of web-based, self-administered, graphical food frequency questionnaire.

    Science.gov (United States)

    Kristal, Alan R; Kolar, Ann S; Fisher, James L; Plascak, Jesse J; Stumbo, Phyllis J; Weiss, Rick; Paskett, Electra D

    2014-04-01

    Computer-administered food frequency questionnaires (FFQs) can address limitations inherent in paper questionnaires by allowing very complex skip patterns, portion size estimation based on food pictures, and real-time error checking. We evaluated a web-based FFQ, the Graphical Food Frequency System (GraFFS). Participants completed the GraFFS, six telephone-administered 24-hour dietary recalls over the next 12 weeks, followed by a second GraFFS. Participants were 40 men and 34 women, aged 18 to 69 years, living in the Columbus, OH, area. Intakes of energy, macronutrients, and 17 micronutrients/food components were estimated from the GraFFS and the mean of all recalls. Bias (second GraFFS minus recalls) was -9%, -5%, +4%, and -4% for energy and percentages of energy from fat, carbohydrate, and protein, respectively. De-attenuated, energy-adjusted correlations (intermethod reliability) between the recalls and the second GraFFS for fat, carbohydrate, protein, and alcohol were 0.82, 0.79, 0.67, and 0.90, respectively; for micronutrients/food components the median was 0.61 and ranged from 0.40 for zinc to 0.92 for beta carotene. The correlations between the two administrations of the GraFFS (test-retest reliability) for fat, carbohydrate, protein, and alcohol were 0.60, 0.63, 0.73, and 0.87, respectively; among micronutrients/food components the median was 0.67 and ranged from 0.49 for vitamin B-12 to 0.82 for fiber. The measurement characteristics of the GraFFS were at least as good as those reported for most paper FFQs, and its high intermethod reliability suggests that further development of computer-administered FFQs is warranted. Copyright © 2014 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.

  14. Children’s Recall of Fast Food Television Advertising—Testing the Adequacy of Food Marketing Regulation

    Science.gov (United States)

    Bernhardt, Amy M.; Wilking, Cara; Gilbert-Diamond, Diane; Emond, Jennifer A.; Sargent, James D.

    2015-01-01

    Background and Aim In the United States, the fast food companies McDonald’s and Burger King participate in marketing self-regulation programs that aim to limit emphasis on premiums and promote emphasis of healthy food choices. We determine what children recall from fast food television advertisements aired by these companies. Methods One hundred children aged 3–7 years were shown McDonald’s and Burger King children’s (MDC & BKC) and adult (MDA & BKA) meal ads, randomly drawn from ads that aired on national US television from 2010–11. Immediately after seeing the ad, children were asked to recall what they had seen and transcripts evaluated for descriptors of food, healthy food (apples or milk), and premiums/tie-ins. Results Premiums/tie-ins were common in children’s but rarely appeared in adult ads, and all children’s ads contained images of healthy foods (apples and milk). Participants were significantly less likely to recall any food after viewing the children’s vs. the adult ad (MDC 32% [95% confidence interval 23, 41] vs. MDA 68% [59, 77]) p food was not significantly different from premium/tie-ins, and participants were significantly more likely to recall other food items than apples or milk. Moreover, premiums/tie-ins were recalled much more frequently than healthy food (MDC 45% [35, 55] vs. 9% [3, 15] pfood advertising indicate that industry self-regulation failed to achieve a de-emphasis on toy premiums and tie-ins and did not adequately communicate healthy menu choices. The methods devised for this study could be used to monitor and better regulate advertising patterns of practice. PMID:25738653

  15. Needle Custom Search: Recall-oriented search on the Web using semantic annotations

    NARCIS (Netherlands)

    Kaptein, Rianne; Koot, Gijs; Huis in 't Veld, Mirjam A.A.; van den Broek, Egon; de Rijke, Maarten; Kenter, Tom; de Vries, A.P.; Zhai, Chen Xiang; de Jong, Franciska M.G.; Radinsky, Kira; Hofmann, Katja

    Web search engines are optimized for early precision, which makes it difficult to perform recall-oriented tasks using these search engines. In this article, we present our tool Needle Custom Search. This tool exploits semantic annotations of Web search results and, thereby, increase the efficiency

  16. Needle Custom Search : Recall-oriented search on the web using semantic annotations

    NARCIS (Netherlands)

    Kaptein, Rianne; Koot, Gijs; Huis in 't Veld, Mirjam A.A.; van den Broek, Egon L.

    2014-01-01

    Web search engines are optimized for early precision, which makes it difficult to perform recall-oriented tasks using these search engines. In this article, we present our tool Needle Custom Search. This tool exploits semantic annotations of Web search results and, thereby, increase the efficiency

  17. Recalls of foods due to microbiological contamination classified by the U.S. Food and Drug Administration, fiscal years 2003 through 2011.

    Science.gov (United States)

    Dey, Manashi; Mayo, Jonathan A; Saville, Deborah; Wolyniak, Cecilia; Klontz, Karl C

    2013-06-01

    Recalls of foods contaminated with pathogens help reduce the transmission of infectious diseases. Here, we summarize the number and nature of foods recalled as a result of microbiological contamination, classified by the U.S. Food and Drug Administration for the period 1 October 2002 through 30 September 2011. Microbiological contamination accounted for 1,395 (42%) of 3,360 recalls of food during this period. Nuts and edible seeds, followed by fishery-seafood products and spices, were the types of products most commonly recalled for microbiological contamination. Salmonella contamination accounted for the greatest number of food products recalled due to microbiological contamination, and was the pathogen most often linked to reported outbreaks involving recalled food products.

  18. A food recall case study in Australia – Towards the development of food safety applications for consumers

    Directory of Open Access Journals (Sweden)

    Adeola Bamgboje-Ayodele

    2016-04-01

    Full Text Available Changes in consumer attitudes, behaviours and purchasing preferences towards different types of food highlight the increased demand for better quality information on safety, quality and provenance of food products and on sustainability of food production processes. These changes offer both new opportunities and risks for food producers who require mechanisms to better understand and respond to changing consumers’ decision-making trends on food.  In the area of food safety, investigation of consumer and producer responses during recall incidents provide an opportunity to holistically understand existing information flows and elicit user requirements necessary for the development of more effective consumer food safety applications.This paper reports on a case study conducted with an Australian premium manufacturing company that experienced a food recall in 2014. The investigation confirms that current Australian food recall response mechanisms do not guarantee a closed loop of communication with all purchasers of a recalled product. It also highlights that producers still face difficulties in understanding how best to effectively understand and respond to different types of consumers. It emerges that recovery from a food incident relies on many factors including pre-existing brand reputation, effective information management, control mechanisms and supply chain partner response. From a consumer perspective, it is evident that consumers’ responses are influenced by various factors that require sensitivity around the choice of information modality and information platform adopted to enhance communications during food recall. The paper highlights the need for further research into understanding consumer food safety behaviours post-purchase to improve the development of consumer food safety applications.

  19. The validity of a web-based FFQ assessed by doubly labelled water and multiple 24-h recalls.

    Science.gov (United States)

    Medin, Anine C; Carlsen, Monica H; Hambly, Catherine; Speakman, John R; Strohmaier, Susanne; Andersen, Lene F

    2017-12-01

    The aim of this study was to validate the estimated habitual dietary intake from a newly developed web-based FFQ (WebFFQ), for use in an adult population in Norway. In total, ninety-two individuals were recruited. Total energy expenditure (TEE) measured by doubly labelled water was used as the reference method for energy intake (EI) in a subsample of twenty-nine women, and multiple 24-h recalls (24HR) were used as the reference method for the relative validation of macronutrients and food groups in the entire sample. Absolute differences, ratios, crude and deattenuated correlations, cross-classifications, Bland-Altman plot and plots between misreporting of EI (EI-TEE) and the relative misreporting of food groups (WebFFQ-24HR) were used to assess the validity. Results showed that EI on group level was not significantly different from TEE measured by doubly labelled water (0·7 MJ/d), but ranking abilities were poor (r -0·18). The relative validation showed an overestimation for the majority of the variables using absolute intakes, especially for the food groups 'vegetables' and 'fish and shellfish', but an improved agreement between the test and reference tool was observed for energy adjusted intakes. Deattenuated correlation coefficients were between 0·22 and 0·89, and low levels of grossly misclassified individuals (0-3 %) were observed for the majority of the energy adjusted variables for macronutrients and food groups. In conclusion, energy estimates from the WebFFQ should be used with caution, but the estimated absolute intakes on group level and ranking abilities seem acceptable for macronutrients and most food groups.

  20. A review of the design and validation of web- and computer-based 24-h dietary recall tools.

    Science.gov (United States)

    Timon, Claire M; van den Barg, Rinske; Blain, Richard J; Kehoe, Laura; Evans, Katie; Walton, Janette; Flynn, Albert; Gibney, Eileen R

    2016-12-01

    Technology-based dietary assessment offers solutions to many of the limitations of traditional dietary assessment methodologies including cost, participation rates and the accuracy of data collected. The 24-h dietary recall (24HDR) method is currently the most utilised method for the collection of dietary intake data at a national level. Recently there have been many developments using web-based platforms to collect food intake data using the principles of the 24HDR method. This review identifies web- and computer-based 24HDR tools that have been developed for both children and adult population groups, and examines common design features and the methods used to investigate the performance and validity of these tools. Overall, there is generally good to strong agreement between web-based 24HDR and respective reference measures for intakes of macro- and micronutrients.

  1. Children's recall of fast food television advertising-testing the adequacy of food marketing regulation.

    Science.gov (United States)

    Bernhardt, Amy M; Wilking, Cara; Gilbert-Diamond, Diane; Emond, Jennifer A; Sargent, James D

    2015-01-01

    In the United States, the fast food companies McDonald's and Burger King participate in marketing self-regulation programs that aim to limit emphasis on premiums and promote emphasis of healthy food choices. We determine what children recall from fast food television advertisements aired by these companies. One hundred children aged 3-7 years were shown McDonald's and Burger King children's (MDC & BKC) and adult (MDA & BKA) meal ads, randomly drawn from ads that aired on national US television from 2010-11. Immediately after seeing the ad, children were asked to recall what they had seen and transcripts evaluated for descriptors of food, healthy food (apples or milk), and premiums/tie-ins. Premiums/tie-ins were common in children's but rarely appeared in adult ads, and all children's ads contained images of healthy foods (apples and milk). Participants were significantly less likely to recall any food after viewing the children's vs. the adult ad (MDC 32% [95% confidence interval 23, 41] vs. MDA 68% [59, 77]) p advertising indicate that industry self-regulation failed to achieve a de-emphasis on toy premiums and tie-ins and did not adequately communicate healthy menu choices. The methods devised for this study could be used to monitor and better regulate advertising patterns of practice.

  2. The insurability of product recall in food supply chains

    NARCIS (Netherlands)

    Meuwissen, M.P.M.; Valeeva, N.I.; Velthuis, A.G.J.; Huirne, R.B.M.

    2006-01-01

    Insurers face growing difficulties with insuring food-related risks among others due to an increasing number of product recalls and an increasing amount of claims being pushed back into the chain. This paper focuses on the risk of product recall in dairy supply chains. The paper aims at providing

  3. Community food webs data and theory

    CERN Document Server

    Cohen, Joel E; Newman, Charles M

    1990-01-01

    Food webs hold a central place in ecology. They describe which organisms feed on which others in natural habitats. This book describes recently discovered empirical regularities in real food webs: it proposes a novel theory unifying many of these regularities, as well as extensive empirical data. After a general introduction, reviewing the empirical and theoretical discoveries about food webs, the second portion of the book shows that community food webs obey several striking phenomenological regularities. Some of these unify, regardless of habitat. Others differentiate, showing that habitat significantly influences structure. The third portion of the book presents a theoretical analysis of some of the unifying empirical regularities. The fourth portion of the book presents 13 community food webs. Collected from scattered sources and carefully edited, they are the empirical basis for the results in the volume. The largest available set of data on community food webs provides a valuable foundation for future s...

  4. Where are the parasites in food webs?

    Science.gov (United States)

    2012-01-01

    This review explores some of the reasons why food webs seem to contain relatively few parasite species when compared to the full diversity of free living species in the system. At present, there are few coherent food web theories to guide scientific studies on parasites, and this review posits that the methods, directions and questions in the field of food web ecology are not always congruent with parasitological inquiry. For example, topological analysis (the primary tool in food web studies) focuses on only one of six important steps in trematode life cycles, each of which requires a stable community dynamic to evolve. In addition, these transmission strategies may also utilize pathways within the food web that are not considered in traditional food web investigations. It is asserted that more effort must be focused on parasite-centric models, and a central theme is that many different approaches will be required. One promising approach is the old energetic perspective, which considers energy as the critical resource for all organisms, and the currency of all food web interactions. From the parasitological point of view, energy can be used to characterize the roles of parasites at all levels in the food web, from individuals to populations to community. The literature on parasite energetics in food webs is very sparse, but the evidence suggests that parasite species richness is low in food webs because parasites are limited by the quantity of energy available to their unique lifestyles. PMID:23092160

  5. Where are the parasites in food webs?

    Directory of Open Access Journals (Sweden)

    Sukhdeo Michael VK

    2012-10-01

    Full Text Available Abstract This review explores some of the reasons why food webs seem to contain relatively few parasite species when compared to the full diversity of free living species in the system. At present, there are few coherent food web theories to guide scientific studies on parasites, and this review posits that the methods, directions and questions in the field of food web ecology are not always congruent with parasitological inquiry. For example, topological analysis (the primary tool in food web studies focuses on only one of six important steps in trematode life cycles, each of which requires a stable community dynamic to evolve. In addition, these transmission strategies may also utilize pathways within the food web that are not considered in traditional food web investigations. It is asserted that more effort must be focused on parasite-centric models, and a central theme is that many different approaches will be required. One promising approach is the old energetic perspective, which considers energy as the critical resource for all organisms, and the currency of all food web interactions. From the parasitological point of view, energy can be used to characterize the roles of parasites at all levels in the food web, from individuals to populations to community. The literature on parasite energetics in food webs is very sparse, but the evidence suggests that parasite species richness is low in food webs because parasites are limited by the quantity of energy available to their unique lifestyles.

  6. Graph Theory Approach for Studying Food Webs

    Science.gov (United States)

    Longjas, A.; Tejedor, A.; Foufoula-Georgiou, E.

    2017-12-01

    Food webs are complex networks of feeding interactions among species in ecological communities. Metrics describing food web structure have been proposed to compare and classify food webs ranging from food chain length, connectance, degree distribution, centrality measures, to the presence of motifs (distinct compartments), among others. However, formal methodologies for studying both food web topology and the dynamic processes operating on them are still lacking. Here, we utilize a quantitative framework using graph theory within which a food web is represented by a directed graph, i.e., a collection of vertices (species or trophic species defined as sets of species sharing the same predators and prey) and directed edges (predation links). This framework allows us to identify apex (environmental "source" node) to outlet (top predators) subnetworks and compute the steady-state flux (e.g., carbon, nutrients, energy etc.) in the food web. We use this framework to (1) construct vulnerability maps that quantify the relative change of flux delivery to the top predators in response to perturbations in prey species (2) identify keystone species, whose loss would precipitate further species extinction, and (3) introduce a suite of graph-theoretic metrics to quantify the topologic (imposed by food web connectivity) and dynamic (dictated by the flux partitioning and distribution) components of a food web's complexity. By projecting food webs into a 2D Topodynamic Complexity Space whose coordinates are given by Number of alternative paths (topologic) and Leakage Index (dynamic), we show that this space provides a basis for food web comparison and provide physical insights into their dynamic behavior.

  7. Recalls API

    Data.gov (United States)

    General Services Administration — This Recalls API allows you to tap into a list of (1) drug and food safety recalls from the Food and Drug Administration, Food Safety and Inspection Service, and...

  8. Parasites in food webs: the ultimate missing links

    Science.gov (United States)

    Lafferty, Kevin D.; Allesina, Stefano; Arim, Matias; Briggs, Cherie J.; De Leo, Giulio A.; Dobson, Andrew P.; Dunne, Jennifer A.; Johnson, Pieter T.J.; Kuris, Armand M.; Marcogliese, David J.; Martinez, Neo D.; Memmott, Jane; Marquet, Pablo A.; McLaughlin, John P.; Mordecai, Eerin A.; Pascual, Mercedes; Poulin, Robert; Thieltges, David W.

    2008-01-01

    Parasitism is the most common consumer strategy among organisms, yet only recently has there been a call for the inclusion of infectious disease agents in food webs. The value of this effort hinges on whether parasites affect food-web properties. Increasing evidence suggests that parasites have the potential to uniquely alter food-web topology in terms of chain length, connectance and robustness. In addition, parasites might affect food-web stability, interaction strength and energy flow. Food-web structure also affects infectious disease dynamics because parasites depend on the ecological networks in which they live. Empirically, incorporating parasites into food webs is straightforward. We may start with existing food webs and add parasites as nodes, or we may try to build food webs around systems for which we already have a good understanding of infectious processes. In the future, perhaps researchers will add parasites while they construct food webs. Less clear is how food-web theory can accommodate parasites. This is a deep and central problem in theoretical biology and applied mathematics. For instance, is representing parasites with complex life cycles as a single node equivalent to representing other species with ontogenetic niche shifts as a single node? Can parasitism fit into fundamental frameworks such as the niche model? Can we integrate infectious disease models into the emerging field of dynamic food-web modelling? Future progress will benefit from interdisciplinary collaborations between ecologists and infectious disease biologists.

  9. Food web framework for size-structured populations

    DEFF Research Database (Denmark)

    Hartvig, Martin; Andersen, Ken Haste; Beyer, Jan

    2011-01-01

    . Parameter values are determined from cross-species analysis of fish communities as life-history omnivory is widespread in aquatic systems, but may be reparameterised for other systems. An ensemble of food webs is generated and the resulting communities are analysed at four levels of organisation: community......We synthesise traditional unstructured food webs, allometric body size scaling, trait-based modelling, and physiologically structured modelling to provide a novel and ecologically relevant tool for size-structured food webs. The framework allows food web models to include ontogenetic growth...... level, species level, trait level, and individual level. The model may be solved analytically by assuming that the community spectrum follows a power law. The analytical solution provides a baseline expectation of the results of complex food web simulations, and agrees well with the predictions...

  10. Food-web dynamics in a large river discontinuum

    Science.gov (United States)

    Cross, Wyatt F.; Baxter, Colden V.; Rosi-Marshall, Emma J.; Hall, Robert O.; Kennedy, Theodore A.; Donner, Kevin C.; Kelly, Holly A. Wellard; Seegert, Sarah E.Z.; Behn, Kathrine E.; Yard, Michael D.

    2013-01-01

    Nearly all ecosystems have been altered by human activities, and most communities are now composed of interacting species that have not co-evolved. These changes may modify species interactions, energy and material flows, and food-web stability. Although structural changes to ecosystems have been widely reported, few studies have linked such changes to dynamic food-web attributes and patterns of energy flow. Moreover, there have been few tests of food-web stability theory in highly disturbed and intensely managed freshwater ecosystems. Such synthetic approaches are needed for predicting the future trajectory of ecosystems, including how they may respond to natural or anthropogenic perturbations. We constructed flow food webs at six locations along a 386-km segment of the Colorado River in Grand Canyon (Arizona, USA) for three years. We characterized food-web structure and production, trophic basis of production, energy efficiencies, and interaction-strength distributions across a spatial gradient of perturbation (i.e., distance from Glen Canyon Dam), as well as before and after an experimental flood. We found strong longitudinal patterns in food-web characteristics that strongly correlated with the spatial position of large tributaries. Above tributaries, food webs were dominated by nonnative New Zealand mudsnails (62% of production) and nonnative rainbow trout (100% of fish production). The simple structure of these food webs led to few dominant energy pathways (diatoms to few invertebrate taxa to rainbow trout), large energy inefficiencies (i.e., Below large tributaries, invertebrate production declined ∼18-fold, while fish production remained similar to upstream sites and comprised predominately native taxa (80–100% of production). Sites below large tributaries had increasingly reticulate and detritus-based food webs with a higher prevalence of omnivory, as well as interaction strength distributions more typical of theoretically stable food webs (i

  11. Food and beverage advertising on children's web sites.

    Science.gov (United States)

    Ustjanauskas, A E; Harris, J L; Schwartz, M B

    2014-10-01

    Food marketing contributes to childhood obesity. Food companies commonly place display advertising on children's web sites, but few studies have investigated this form of advertising. Document the number of food and beverage display advertisements viewed on popular children's web sites, nutritional quality of advertised brands and proportion of advertising approved by food companies as healthier dietary choices for child-directed advertising. Syndicated Internet exposure data identified popular children's web sites and food advertisements viewed on these web sites from July 2009 through June 2010. Advertisements were classified according to food category and companies' participation in food industry self-regulation. The percent of advertisements meeting government-proposed nutrition standards was calculated. 3.4 billion food advertisements appeared on popular children's web sites; 83% on just four web sites. Breakfast cereals and fast food were advertised most often (64% of ads). Most ads (74%) promoted brands approved by companies for child-directed advertising, but 84% advertised products that were high in fat, sugar and/or sodium. Ads for foods designated by companies as healthier dietary choices appropriate for child-directed advertising were least likely to meet independent nutrition standards. Most foods advertised on popular children's web sites do not meet independent nutrition standards. Further improvements to industry self-regulation are required. © 2013 The Authors. Pediatric Obesity © 2013 International Association for the Study of Obesity.

  12. Fun With Food Webs

    Science.gov (United States)

    Smith, Karl D.

    1977-01-01

    Explains an upper elementary game of tag that illustrates energy flow in food webs using candy bars as food sources. A follow-up field trip to a river and five language arts projects are also suggested. (CS)

  13. Compilation and network analyses of cambrian food webs.

    Directory of Open Access Journals (Sweden)

    Jennifer A Dunne

    2008-04-01

    Full Text Available A rich body of empirically grounded theory has developed about food webs--the networks of feeding relationships among species within habitats. However, detailed food-web data and analyses are lacking for ancient ecosystems, largely because of the low resolution of taxa coupled with uncertain and incomplete information about feeding interactions. These impediments appear insurmountable for most fossil assemblages; however, a few assemblages with excellent soft-body preservation across trophic levels are candidates for food-web data compilation and topological analysis. Here we present plausible, detailed food webs for the Chengjiang and Burgess Shale assemblages from the Cambrian Period. Analyses of degree distributions and other structural network properties, including sensitivity analyses of the effects of uncertainty associated with Cambrian diet designations, suggest that these early Paleozoic communities share remarkably similar topology with modern food webs. Observed regularities reflect a systematic dependence of structure on the numbers of taxa and links in a web. Most aspects of Cambrian food-web structure are well-characterized by a simple "niche model," which was developed for modern food webs and takes into account this scale dependence. However, a few aspects of topology differ between the ancient and recent webs: longer path lengths between species and more species in feeding loops in the earlier Chengjiang web, and higher variability in the number of links per species for both Cambrian webs. Our results are relatively insensitive to the exclusion of low-certainty or random links. The many similarities between Cambrian and recent food webs point toward surprisingly strong and enduring constraints on the organization of complex feeding interactions among metazoan species. The few differences could reflect a transition to more strongly integrated and constrained trophic organization within ecosystems following the rapid

  14. Compilation and network analyses of cambrian food webs.

    Science.gov (United States)

    Dunne, Jennifer A; Williams, Richard J; Martinez, Neo D; Wood, Rachel A; Erwin, Douglas H

    2008-04-29

    A rich body of empirically grounded theory has developed about food webs--the networks of feeding relationships among species within habitats. However, detailed food-web data and analyses are lacking for ancient ecosystems, largely because of the low resolution of taxa coupled with uncertain and incomplete information about feeding interactions. These impediments appear insurmountable for most fossil assemblages; however, a few assemblages with excellent soft-body preservation across trophic levels are candidates for food-web data compilation and topological analysis. Here we present plausible, detailed food webs for the Chengjiang and Burgess Shale assemblages from the Cambrian Period. Analyses of degree distributions and other structural network properties, including sensitivity analyses of the effects of uncertainty associated with Cambrian diet designations, suggest that these early Paleozoic communities share remarkably similar topology with modern food webs. Observed regularities reflect a systematic dependence of structure on the numbers of taxa and links in a web. Most aspects of Cambrian food-web structure are well-characterized by a simple "niche model," which was developed for modern food webs and takes into account this scale dependence. However, a few aspects of topology differ between the ancient and recent webs: longer path lengths between species and more species in feeding loops in the earlier Chengjiang web, and higher variability in the number of links per species for both Cambrian webs. Our results are relatively insensitive to the exclusion of low-certainty or random links. The many similarities between Cambrian and recent food webs point toward surprisingly strong and enduring constraints on the organization of complex feeding interactions among metazoan species. The few differences could reflect a transition to more strongly integrated and constrained trophic organization within ecosystems following the rapid diversification of species, body

  15. Integrating ecosystem engineering and food webs

    NARCIS (Netherlands)

    Sanders, Dirk; Jones, Clive G.; Thebault, Elisa; Bouma, Tjeerd J.; van der Heide, Tjisse; van Belzen, Jim; Barot, Sebastien

    Ecosystem engineering, the physical modification of the environment by organisms, is a common and often influential process whose significance to food web structure and dynamics is largely unknown. In the light of recent calls to expand food web studies to include non-trophic interactions, we

  16. Integrating ecosystem engineering and food webs

    NARCIS (Netherlands)

    Sanders, D.; Jones, C.G.; Thébault, E.; Bouma, T.J.; van der Heide, T.; van Belzen, J.; Barot, S.

    2014-01-01

    Ecosystem engineering, the physical modification of the environment by organisms, is a common and often influential process whose significance to food web structure and dynamics is largely unknown. In the light of recent calls to expand food web studies to include non-trophic interactions, we

  17. Soil food web changes during spontaneous succession at post mining sites: a possible ecosystem engineering effect on food web organization?

    Science.gov (United States)

    Frouz, Jan; Thébault, Elisa; Pižl, Václav; Adl, Sina; Cajthaml, Tomáš; Baldrián, Petr; Háněl, Ladislav; Starý, Josef; Tajovský, Karel; Materna, Jan; Nováková, Alena; de Ruiter, Peter C

    2013-01-01

    Parameters characterizing the structure of the decomposer food web, biomass of the soil microflora (bacteria and fungi) and soil micro-, meso- and macrofauna were studied at 14 non-reclaimed 1- 41-year-old post-mining sites near the town of Sokolov (Czech Republic). These observations on the decomposer food webs were compared with knowledge of vegetation and soil microstructure development from previous studies. The amount of carbon entering the food web increased with succession age in a similar way as the total amount of C in food web biomass and the number of functional groups in the food web. Connectance did not show any significant changes with succession age, however. In early stages of the succession, the bacterial channel dominated the food web. Later on, in shrub-dominated stands, the fungal channel took over. Even later, in the forest stage, the bacterial channel prevailed again. The best predictor of fungal bacterial ratio is thickness of fermentation layer. We argue that these changes correspond with changes in topsoil microstructure driven by a combination of plant organic matter input and engineering effects of earthworms. In early stages, soil is alkaline, and a discontinuous litter layer on the soil surface promotes bacterial biomass growth, so the bacterial food web channel can dominate. Litter accumulation on the soil surface supports the development of the fungal channel. In older stages, earthworms arrive, mix litter into the mineral soil and form an organo-mineral topsoil, which is beneficial for bacteria and enhances the bacterial food web channel.

  18. Children?s Recall of Fast Food Television Advertising?Testing the Adequacy of Food Marketing Regulation

    OpenAIRE

    Bernhardt, Amy M.; Wilking, Cara; Gilbert-Diamond, Diane; Emond, Jennifer A.; Sargent, James D.

    2015-01-01

    Background and Aim In the United States, the fast food companies McDonald?s and Burger King participate in marketing self-regulation programs that aim to limit emphasis on premiums and promote emphasis of healthy food choices. We determine what children recall from fast food television advertisements aired by these companies. Methods One hundred children aged 3?7 years were shown McDonald?s and Burger King children?s (MDC & BKC) and adult (MDA & BKA) meal ads, randomly drawn from ads that air...

  19. Magazine adverts for healthy and less healthy foods: effects on recall but not hunger or food choice by pre-adolescent children.

    Science.gov (United States)

    King, Lorraine; Hill, Andrew J

    2008-07-01

    The marketing of foods to children has been criticised by parents and academics alike and the control of such advertising is being considered by politicians. Much of the current research focuses on TV advertising. This study aimed to investigate the effects of exposure to printed advertisements for healthy, less healthy and non-food products on children's mood, hunger, food choice and product recall. Accordingly, 309 children (mean age 9.7 years) received booklets in a quasi-random order. Each booklet contained one of the three types of adverts, ratings of current self-perception and a food choice measure. The booklets were presented as a school-based media literacy exercise. Body weight, height and body satisfaction were assessed 1 week later. The three groups did not differ in the effect on current state or end of session food choice. However, children recalled more of the less healthy food products, even when accounting for recent exposure. Greater product recall of less healthy foods is relevant to future consumption but has a number of possible interpretations. The further exploration of non-TV food marketing is warranted at a time when marketing through these channels is increasing, not least as a result of greater TV advertising regulations.

  20. Usage and Recall of the Food Stamp Office Resource Kit (FSORK) by Food Stamp Applicants in 4 California Counties

    Science.gov (United States)

    Ghirardelli, Alyssa; Linares, Amanda; Fong, Amy

    2011-01-01

    Objective: To evaluate recall and usage of the Food Stamp Office Resource Kit (FSORK), a set of nutrition education materials designed for use in food stamp offices. Design: Client intercept exit surveys, an environmental scan, and individual observations of clients in the food stamp office. Setting: Four food stamp offices in California.…

  1. Overestimation of infant and toddler energy intake by 24-h recall compared with weighed food records.

    Science.gov (United States)

    Fisher, Jennifer O; Butte, Nancy F; Mendoza, Patricia M; Wilson, Theresa A; Hodges, Eric A; Reidy, Kathleen C; Deming, Denise

    2008-08-01

    Twenty-four-hour dietary recalls have been used in large surveys of infant and toddler energy intake, but the accuracy of the method for young children is not well documented. We aimed to determine the accuracy of infant and toddler energy intakes by a single, telephone-administered, multiple-pass 24-h recall as compared with 3-d weighed food records. A within-subjects design was used in which a 24-h recall and 3-d weighed food records were completed within 2 wk by 157 mothers (56 non-Hispanic white, 51 non-Hispanic black, and 50 Hispanic) of 7-11-mo-old infants or 12-24-mo-old toddlers. Child and caregiver anthropometrics, child eating patterns, and caregiver demographics and social desirability were evaluated as correlates of reporting bias. Intakes based on 3-d weighed food records were within 5% of estimated energy requirements. Compared with the 3-d weighed food records, the 24-h recall overestimated energy intake by 13% among infants (740 +/- 154 and 833 +/- 255 kcal, respectively) and by 29% among toddlers (885 +/- 197 and 1140 +/- 299 kcal, respectively). Eating patterns (ie, frequency and location) did not differ appreciably between methods. Macronutrient and micronutrient intakes were higher by 24-h recall than by 3-d weighed food record. Dairy and grains contributed the most energy to the diet and accounted for 74% and 54% of the overestimation seen in infants and toddlers, respectively. Greater overestimation was associated with a greater number of food items reported by the caregiver and lower child weight-for-length z scores. The use of a single, telephone-administered, multiple-pass 24-h recall may significantly overestimate infant or toddler energy and nutrient intakes because of portion size estimation errors.

  2. [Validity and reproducibility of an Internet-based questionnaire (Web-CAAFE) to evaluate the food consumption of students aged 7 to 15 years].

    Science.gov (United States)

    Jesus, Gilmar Mercês de; Assis, Maria Alice Altenburg de; Kupek, Emil

    2017-06-05

    The study evaluated the validity and reproducibility of the food consumption section of the questionnaire Food Intake and Physical Activity of School Children (Web-CAAFE), an Internet-based software for the qualitative measurement of food consumption by recalling the previous day. A total of 390 students in grades 2 to 5 (7 to 15 years) of a semi-integral public school participated in the study. The validity was tested by comparing the report in the Web-CAAFE and the direct observation of food consumed in the school in the previous day. The reproducibility was evaluated in a sub-sample of 92 schoolchildren, by comparing repeated reports in the Web-CAAFE on the same day. Probabilities of accuracy in the Web-CAAFE report in relation to the observation (matches, omissions and intrusions and respective 95% confidence intervals) among seven food groups were estimated through multinomial logistic regression. The average for the match rate was 81.4% (variation: 62% sweets and 98% beans); for the omission rate was 16.2% (variation between 2.1% dairy products and 28.5% sweets); for the intrusion rate was 7.1% (variation between 1.3% beans and 13.8% cereals). Sweets, cereals and processed foods, snack foods and fried foods simultaneously exhibited higher rates of omission and intrusion. Students 10 years of age or older had lower probabilities of intruding food items. There were no significant variations in the accuracy of the report between repeated measures. The Web-CAAFE was a valid and reliable instrument for the evaluation of food consumption, when applied to students in grades 2 to 5 of public schools.

  3. Major dimensions in food-web structure properties

    NARCIS (Netherlands)

    Vermaat, J.E.; Dunne, J. A.; Gilbert, A.J.

    2009-01-01

    The covariance among a range of 20 network structural properties of food webs plus net primary productivity was assessed for 14 published food webs using principal components analysis. Three primary components explained 84% of the variability in the data sets, suggesting substantial covariance among

  4. Zinc in an ultraoligotrophic lake food web.

    Science.gov (United States)

    Montañez, Juan Cruz; Arribére, María A; Rizzo, Andrea; Arcagni, Marina; Campbell, Linda; Ribeiro Guevara, Sergio

    2018-03-21

    Zinc (Zn) bioaccumulation and trophic transfer were analyzed in the food web of Lake Nahuel Huapi, a deep, unpolluted ultraoligotrophic system in North Patagonia. Benthic macroinvertebrates, plankton, and native and introduced fish were collected at three sites. The effect of pyroclastic inputs on Zn levels in lacustrine food webs was assessed by studying the impact of the eruption of Puyehue-Cordón Caulle volcanic complex (PCCVC) in 2011, by performing three sampling campaigns immediately before and after the PCCVC eruption, and after 2 years of recovery of the ecosystem. Zinc trophodynamics in L. Nahuel Huapi food web was assessed using nitrogen stable isotopes (δ 15 N). There was no significant increase of Zn concentrations ([Zn]) in L. Nahuel Huapi biota after the PCCVC eruption, despite the evidence of [Zn] increase in lake water that could be associated with volcanic ash leaching. The organisms studied exhibited [Zn] above the threshold level considered for dietary deficiency, regulating Zn adequately even under a catastrophic situations like PCCVC 2011 eruption. Zinc concentrations exhibited a biodilution pattern in the lake's food web. To the best of our knowledge, present research is the first report of Zn biodilution in lacustrine systems, and the first to study Zn transfer in a freshwater food web including both pelagic and benthic compartments.

  5. Food Enterprise Web Design Based on User Experience

    OpenAIRE

    Fei Wang

    2015-01-01

    Excellent auxiliary food enterprise web design conveyed good visual transmission effect through user experience. This study was based on the food enterprise managers and customers as the main operating object to get the performance of the web page creation, web page design not only focused on the function and work efficiency, the most important thing was that the user experience in the process of web page interaction.

  6. Food web complexity and stability across habitat connectivity gradients.

    Science.gov (United States)

    LeCraw, Robin M; Kratina, Pavel; Srivastava, Diane S

    2014-12-01

    The effects of habitat connectivity on food webs have been studied both empirically and theoretically, yet the question of whether empirical results support theoretical predictions for any food web metric other than species richness has received little attention. Our synthesis brings together theory and empirical evidence for how habitat connectivity affects both food web stability and complexity. Food web stability is often predicted to be greatest at intermediate levels of connectivity, representing a compromise between the stabilizing effects of dispersal via rescue effects and prey switching, and the destabilizing effects of dispersal via regional synchronization of population dynamics. Empirical studies of food web stability generally support both this pattern and underlying mechanisms. Food chain length has been predicted to have both increasing and unimodal relationships with connectivity as a result of predators being constrained by the patch occupancy of their prey. Although both patterns have been documented empirically, the underlying mechanisms may differ from those predicted by models. In terms of other measures of food web complexity, habitat connectivity has been empirically found to generally increase link density but either reduce or have no effect on connectance, whereas a unimodal relationship is expected. In general, there is growing concordance between empirical patterns and theoretical predictions for some effects of habitat connectivity on food webs, but many predictions remain to be tested over a full connectivity gradient, and empirical metrics of complexity are rarely modeled. Closing these gaps will allow a deeper understanding of how natural and anthropogenic changes in connectivity can affect real food webs.

  7. Biodiversity maintenance in food webs with regulatory environmental feedbacks.

    Science.gov (United States)

    Bagdassarian, Carey K; Dunham, Amy E; Brown, Christopher G; Rauscher, Daniel

    2007-04-21

    Although the food web is one of the most fundamental and oldest concepts in ecology, elucidating the strategies and structures by which natural communities of species persist remains a challenge to empirical and theoretical ecologists. We show that simple regulatory feedbacks between autotrophs and their environment when embedded within complex and realistic food-web models enhance biodiversity. The food webs are generated through the niche-model algorithm and coupled with predator-prey dynamics, with and without environmental feedbacks at the autotroph level. With high probability and especially at lower, more realistic connectance levels, regulatory environmental feedbacks result in fewer species extinctions, that is, in increased species persistence. These same feedback couplings, however, also sensitize food webs to environmental stresses leading to abrupt collapses in biodiversity with increased forcing. Feedback interactions between species and their material environments anchor food-web persistence, adding another dimension to biodiversity conservation. We suggest that the regulatory features of two natural systems, deep-sea tubeworms with their microbial consortia and a soil ecosystem manifesting adaptive homeostatic changes, can be embedded within niche-model food-web dynamics.

  8. Does an Adolescent’s Accuracy of Recall Improve with a Second 24-h Dietary Recall?

    Directory of Open Access Journals (Sweden)

    Deborah A. Kerr

    2015-05-01

    Full Text Available The multiple-pass 24-h dietary recall is used in most national dietary surveys. Our purpose was to assess if adolescents’ accuracy of recall improved when a 5-step multiple-pass 24-h recall was repeated. Participants (n = 24, were Chinese-American youths aged between 11 and 15 years and lived in a supervised environment as part of a metabolic feeding study. The 24-h recalls were conducted on two occasions during the first five days of the study. The four steps (quick list; forgotten foods; time and eating occasion; detailed description of the food/beverage of the 24-h recall were assessed for matches by category. Differences were observed in the matching for the time and occasion step (p < 0.01, detailed description (p < 0.05 and portion size matching (p < 0.05. Omission rates were higher for the second recall (p < 0.05 quick list; p < 0.01 forgotten foods. The adolescents over-estimated energy intake on the first (11.3% ± 22.5%; p < 0.05 and second recall (10.1% ± 20.8% compared with the known food and beverage items. These results suggest that the adolescents’ accuracy to recall food items declined with a second 24-h recall when repeated over two non-consecutive days.

  9. Food-web stability signals critical transitions in temperate shallow lakes.

    Science.gov (United States)

    Kuiper, Jan J; van Altena, Cassandra; de Ruiter, Peter C; van Gerven, Luuk P A; Janse, Jan H; Mooij, Wolf M

    2015-07-15

    A principal aim of ecologists is to identify critical levels of environmental change beyond which ecosystems undergo radical shifts in their functioning. Both food-web theory and alternative stable states theory provide fundamental clues to mechanisms conferring stability to natural systems. Yet, it is unclear how the concept of food-web stability is associated with the resilience of ecosystems susceptible to regime change. Here, we use a combination of food web and ecosystem modelling to show that impending catastrophic shifts in shallow lakes are preceded by a destabilizing reorganization of interaction strengths in the aquatic food web. Analysis of the intricate web of trophic interactions reveals that only few key interactions, involving zooplankton, diatoms and detritus, dictate the deterioration of food-web stability. Our study exposes a tight link between food-web dynamics and the dynamics of the whole ecosystem, implying that trophic organization may serve as an empirical indicator of ecosystem resilience.

  10. Landscape variation influences trophic cascades in dengue vector food webs.

    Science.gov (United States)

    Weterings, Robbie; Umponstira, Chanin; Buckley, Hannah L

    2018-02-01

    The epidemiology of vector-borne diseases is governed by a structured array of correlative and causative factors, including landscape (for example, rural versus urban), abiotic (for example, weather), and biotic (for example, food web) factors. Studies of mosquito-borne diseases rarely address these multiple factors at large spatial scales, which limits insights into how human alterations of landscapes and food webs alter mosquito abundance. We used structural equation modeling to identify the relative magnitude and direction of landscape, abiotic, and food web factors on Aedes larvae and adults across 70 sites in northern Thailand. Food web factors were modeled as mosquito-predator trophic cascades. Landscape context affected mosquito-predator communities in aquatic and terrestrial environments via cascading food web interactions. Several mosquito predators within these food webs showed potential as biocontrol agents in mosquito population control, but their potentials for control were landscape-dependent. In terrestrial food webs, the habitat-sensitive tokay gecko structured mosquito-predator communities, indicating that a conservation approach to vector control could be a useful addition to existing control efforts.

  11. Challenges in converting an interviewer-administered food probe database to self-administration in the National Cancer Institute Automated Self-administered 24-Hour Recall (ASA24).

    Science.gov (United States)

    Zimmerman, Thea Palmer; Hull, Stephen G; McNutt, Suzanne; Mittl, Beth; Islam, Noemi; Guenther, Patricia M; Thompson, Frances E; Potischman, Nancy A; Subar, Amy F

    2009-12-01

    The National Cancer Institute (NCI) is developing an automated, self-administered 24-hour dietary recall (ASA24) application to collect and code dietary intake data. The goal of the ASA24 development is to create a web-based dietary interview based on the US Department of Agriculture (USDA) Automated Multiple Pass Method (AMPM) instrument currently used in the National Health and Nutrition Examination Survey (NHANES). The ASA24 food list, detail probes, and portion probes were drawn from the AMPM instrument; portion-size pictures from Baylor College of Medicine's Food Intake Recording Software System (FIRSSt) were added; and the food code/portion code assignments were linked to the USDA Food and Nutrient Database for Dietary Studies (FNDDS). The requirements that the interview be self-administered and fully auto-coded presented several challenges as the AMPM probes and responses were linked with the FNDDS food codes and portion pictures. This linking was accomplished through a "food pathway," or the sequence of steps that leads from a respondent's initial food selection, through the AMPM probes and portion pictures, to the point at which a food code and gram weight portion size are assigned. The ASA24 interview database that accomplishes this contains more than 1,100 food probes and more than 2 million food pathways and will include about 10,000 pictures of individual foods depicting up to 8 portion sizes per food. The ASA24 will make the administration of multiple days of recalls in large-scale studies economical and feasible.

  12. Medical Services: DoD Hazardous Food and Nonprescription Drug Recall System

    Science.gov (United States)

    1986-08-15

    This publication implements policy of the Office of the Under Secretary of Defense for Research and Engineering for the establishment of a hazardous ... food and nonprescription drug recall system. It has been coordinated with and concurred in by the DMSB and the Services.

  13. Isotopic diversity indices: how sensitive to food web structure?

    Science.gov (United States)

    Brind'Amour, Anik; Dubois, Stanislas F

    2013-01-01

    Recently revisited, the concept of niche ecology has lead to the formalisation of functional and trophic niches using stable isotope ratios. Isotopic diversity indices (IDI) derived from a set of measures assessing the dispersion/distribution of points in the δ-space were recently suggested and increasingly used in the literature. However, three main critics emerge from the use of these IDI: 1) they fail to account for the isotopic sources overlap, 2) some indices are highly sensitive to the number of species and/or the presence of rare species, and 3) the lack of standardization prevents any spatial and temporal comparisons. Using simulations we investigated the ability of six commonly used IDI to discriminate among different trophic food web structures, with a focus on the first two critics. We tested the sensitivity of the IDI to five food web structures along a gradient of sources overlap, varying from two distinct food chains with differentiated sources to two superimposed food chains sharing two sources. For each of the food web structure we varied the number of species (from 10 to 100 species) and the type of species feeding behaviour (i.e. random or selective feeding). Values of IDI were generally larger in food webs with distinct basal sources and tended to decrease as the superimposition of the food chains increased. This was more pronounced when species displayed food preferences in comparison to food webs where species fed randomly on any prey. The number of species composing the food web also had strong effects on the metrics, including those that were supposedly less sensitive to small sample size. In all cases, computing IDI on food webs with low numbers of species always increases the uncertainty of the metrics. A threshold of ~20 species was detected above which several metrics can be safely used.

  14. The inverse niche model for food webs with parasites

    Science.gov (United States)

    Warren, Christopher P.; Pascual, Mercedes; Lafferty, Kevin D.; Kuris, Armand M.

    2010-01-01

    Although parasites represent an important component of ecosystems, few field and theoretical studies have addressed the structure of parasites in food webs. We evaluate the structure of parasitic links in an extensive salt marsh food web, with a new model distinguishing parasitic links from non-parasitic links among free-living species. The proposed model is an extension of the niche model for food web structure, motivated by the potential role of size (and related metabolic rates) in structuring food webs. The proposed extension captures several properties observed in the data, including patterns of clustering and nestedness, better than does a random model. By relaxing specific assumptions, we demonstrate that two essential elements of the proposed model are the similarity of a parasite's hosts and the increasing degree of parasite specialization, along a one-dimensional niche axis. Thus, inverting one of the basic rules of the original model, the one determining consumers' generality appears critical. Our results support the role of size as one of the organizing principles underlying niche space and food web topology. They also strengthen the evidence for the non-random structure of parasitic links in food webs and open the door to addressing questions concerning the consequences and origins of this structure.

  15. Food Web Assembly Rules for Generalized Lotka-Volterra Equations.

    Directory of Open Access Journals (Sweden)

    Jan O Haerter

    2016-02-01

    Full Text Available In food webs, many interacting species coexist despite the restrictions imposed by the competitive exclusion principle and apparent competition. For the generalized Lotka-Volterra equations, sustainable coexistence necessitates nonzero determinant of the interaction matrix. Here we show that this requirement is equivalent to demanding that each species be part of a non-overlapping pairing, which substantially constrains the food web structure. We demonstrate that a stable food web can always be obtained if a non-overlapping pairing exists. If it does not, the matrix rank can be used to quantify the lack of niches, corresponding to unpaired species. For the species richness at each trophic level, we derive the food web assembly rules, which specify sustainable combinations. In neighboring levels, these rules allow the higher level to avert competitive exclusion at the lower, thereby incorporating apparent competition. In agreement with data, the assembly rules predict high species numbers at intermediate levels and thinning at the top and bottom. Using comprehensive food web data, we demonstrate how omnivores or parasites with hosts at multiple trophic levels can loosen the constraints and help obtain coexistence in food webs. Hence, omnivory may be the glue that keeps communities intact even under extinction or ecological release of species.

  16. Food Web Assembly Rules for Generalized Lotka-Volterra Equations.

    Science.gov (United States)

    Haerter, Jan O; Mitarai, Namiko; Sneppen, Kim

    2016-02-01

    In food webs, many interacting species coexist despite the restrictions imposed by the competitive exclusion principle and apparent competition. For the generalized Lotka-Volterra equations, sustainable coexistence necessitates nonzero determinant of the interaction matrix. Here we show that this requirement is equivalent to demanding that each species be part of a non-overlapping pairing, which substantially constrains the food web structure. We demonstrate that a stable food web can always be obtained if a non-overlapping pairing exists. If it does not, the matrix rank can be used to quantify the lack of niches, corresponding to unpaired species. For the species richness at each trophic level, we derive the food web assembly rules, which specify sustainable combinations. In neighboring levels, these rules allow the higher level to avert competitive exclusion at the lower, thereby incorporating apparent competition. In agreement with data, the assembly rules predict high species numbers at intermediate levels and thinning at the top and bottom. Using comprehensive food web data, we demonstrate how omnivores or parasites with hosts at multiple trophic levels can loosen the constraints and help obtain coexistence in food webs. Hence, omnivory may be the glue that keeps communities intact even under extinction or ecological release of species.

  17. Food marketing on popular children's web sites: a content analysis.

    Science.gov (United States)

    Alvy, Lisa M; Calvert, Sandra L

    2008-04-01

    In 2006 the Institute of Medicine (IOM) concluded that food marketing was a contributor to childhood obesity in the United States. One recommendation of the IOM committee was for research on newer marketing venues, such as Internet Web sites. The purpose of this cross-sectional study was to answer the IOM's call by examining food marketing on popular children's Web sites. Ten Web sites were selected based on market research conducted by KidSay, which identified favorite sites of children aged 8 to 11 years during February 2005. Using a standardized coding form, these sites were examined page by page for the existence, type, and features of food marketing. Web sites were compared using chi2 analyses. Although food marketing was not pervasive on the majority of the sites, seven of the 10 Web sites contained food marketing. The products marketed were primarily candy, cereal, quick serve restaurants, and snacks. Candystand.com, a food product site, contained a significantly greater amount of food marketing than the other popular children's Web sites. Because the foods marketed to children are not consistent with a healthful diet, nutrition professionals should consider joining advocacy groups to pressure industry to reduce online food marketing directed at youth.

  18. Using the Theory of Planned Behavior to predict intention to comply with a food recall message.

    Science.gov (United States)

    Freberg, Karen

    2013-01-01

    The Theory of Planned Behavior (TPB) has provided considerable insight into the public's intention to comply with many different health-related messages, but has not been applied previously to intention to comply with food safety recommendations and recalls ( Hallman & Cuite, 2010 ). Because food recalls can differ from other health messages in their urgency, timing, and cessation, the applicability of the TPB in this domain is unknown. The research reported here attempted to address this gap using a nationally representative consumer panel. Results showed that, consistent with the theory's predictions, attitudes and subjective norms were predictive of the intention to comply with a food recall message, with attitudes having a much greater impact on intent to comply than subjective norms. Perceived behavioral control failed to predict intention to comply. Implications of these results for health public relations and crisis communications and recommendations for future research were discussed.

  19. Barcoding a quantified food web: crypsis, concepts, ecology and hypotheses.

    Directory of Open Access Journals (Sweden)

    M Alex Smith

    Full Text Available The efficient and effective monitoring of individuals and populations is critically dependent on correct species identification. While this point may seem obvious, identifying the majority of the more than 100 natural enemies involved in the spruce budworm (Choristoneura fumiferana--SBW food web remains a non-trivial endeavor. Insect parasitoids play a major role in the processes governing the population dynamics of SBW throughout eastern North America. However, these species are at the leading edge of the taxonomic impediment and integrating standardized identification capacity into existing field programs would provide clear benefits. We asked to what extent DNA barcoding the SBW food web would alter our understanding of the diversity and connectence of the food web and the frequency of generalists vs. specialists in different forest habitats. We DNA barcoded over 10% of the insects collected from the SBW food web in three New Brunswick forest plots from 1983 to 1993. For 30% of these specimens, we amplified at least one additional nuclear region. When the nodes of the food web were estimated based on barcode divergences (using molecular operational taxonomic units (MOTU or phylogenetic diversity (PD--the food web became much more diverse and connectence was reduced. We tested one measure of food web structure (the "bird feeder effect" and found no difference compared to the morphologically based predictions. Many, but not all, of the presumably polyphagous parasitoids now appear to be morphologically-cryptic host-specialists. To our knowledge, this project is the first to barcode a food web in which interactions have already been well-documented and described in space, time and abundance. It is poised to be a system in which field-based methods permit the identification capacity required by forestry scientists. Food web barcoding provided an effective tool for the accurate identification of all species involved in the cascading effects of

  20. Barcoding a quantified food web: crypsis, concepts, ecology and hypotheses.

    Science.gov (United States)

    Smith, M Alex; Eveleigh, Eldon S; McCann, Kevin S; Merilo, Mark T; McCarthy, Peter C; Van Rooyen, Kathleen I

    2011-01-01

    The efficient and effective monitoring of individuals and populations is critically dependent on correct species identification. While this point may seem obvious, identifying the majority of the more than 100 natural enemies involved in the spruce budworm (Choristoneura fumiferana--SBW) food web remains a non-trivial endeavor. Insect parasitoids play a major role in the processes governing the population dynamics of SBW throughout eastern North America. However, these species are at the leading edge of the taxonomic impediment and integrating standardized identification capacity into existing field programs would provide clear benefits. We asked to what extent DNA barcoding the SBW food web would alter our understanding of the diversity and connectence of the food web and the frequency of generalists vs. specialists in different forest habitats. We DNA barcoded over 10% of the insects collected from the SBW food web in three New Brunswick forest plots from 1983 to 1993. For 30% of these specimens, we amplified at least one additional nuclear region. When the nodes of the food web were estimated based on barcode divergences (using molecular operational taxonomic units (MOTU) or phylogenetic diversity (PD)--the food web became much more diverse and connectence was reduced. We tested one measure of food web structure (the "bird feeder effect") and found no difference compared to the morphologically based predictions. Many, but not all, of the presumably polyphagous parasitoids now appear to be morphologically-cryptic host-specialists. To our knowledge, this project is the first to barcode a food web in which interactions have already been well-documented and described in space, time and abundance. It is poised to be a system in which field-based methods permit the identification capacity required by forestry scientists. Food web barcoding provided an effective tool for the accurate identification of all species involved in the cascading effects of future budworm

  1. 21 CFR 7.42 - Recall strategy.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Recall strategy. 7.42 Section 7.42 Food and Drugs....42 Recall strategy. (a) General. (1) A recall strategy that takes into account the following factors... in the market-place. (v) Continued availability of essential products. (2) The Food and Drug...

  2. An experimental test of a fundamental food web motif.

    Science.gov (United States)

    Rip, Jason M K; McCann, Kevin S; Lynn, Denis H; Fawcett, Sonia

    2010-06-07

    Large-scale changes to the world's ecosystem are resulting in the deterioration of biostructure-the complex web of species interactions that make up ecological communities. A difficult, yet crucial task is to identify food web structures, or food web motifs, that are the building blocks of this baroque network of interactions. Once identified, these food web motifs can then be examined through experiments and theory to provide mechanistic explanations for how structure governs ecosystem stability. Here, we synthesize recent ecological research to show that generalist consumers coupling resources with different interaction strengths, is one such motif. This motif amazingly occurs across an enormous range of spatial scales, and so acts to distribute coupled weak and strong interactions throughout food webs. We then perform an experiment that illustrates the importance of this motif to ecological stability. We find that weak interactions coupled to strong interactions by generalist consumers dampen strong interaction strengths and increase community stability. This study takes a critical step by isolating a common food web motif and through clear, experimental manipulation, identifies the fundamental stabilizing consequences of this structure for ecological communities.

  3. Recall in the food industry: a health strategy to implement in Colombia

    Directory of Open Access Journals (Sweden)

    Jhon Jairo Bejarano-Roncancio

    2016-10-01

    Full Text Available Sanitary and phytosanitary measures taken by international markets have led the food industry to develop technical warnings during marketing processes. Recall is one of the strategies used by some states to regulate such warnings. This process, which involves withdrawal of products from the market, prevents negative impacts on the health of the population and the reputation of the food industry, since safety and quality of food that reaches the consumer is ensured. Recall requires a withdrawal plan from shelves at retail sites or at any of the stages of production; therefore, a tracking system must be implemented to track products throughout the entire production chain by using proper coding. Similarly, this strategy requires a legal and regulatory framework in each country and collaboration from the industry, consumers and consumer associations and leagues. Colombia has developed a management system for health warnings to make decisions in order to protect public health in the country, but they are limited to two warning systems working in coordination with the health warnings issued by international regulatory bodies with their own systems.

  4. Parasites in the Wadden Sea food web

    Science.gov (United States)

    Thieltges, David W.; Engelsma, Marc Y.; Wendling, Carolin C.; Wegner, K. Mathias

    2013-09-01

    While the free-living fauna of the Wadden Sea has received much interest, little is known on the distribution and effects of parasites in the Wadden Sea food web. However, recent studies on this special type of trophic interaction indicate a high diversity of parasites in the Wadden Sea and suggest a multitude of effects on the hosts. This also includes effects on specific predator-prey relationships and the general structure of the food web. Focussing on molluscs, a major group in the Wadden Sea in terms of biomass and abundance and an important link between primary producers and predators, we review existing studies and exemplify the ecological role of parasites in the Wadden Sea food web. First, we give a brief inventory of parasites occurring in the Wadden Sea, ranging from microparasites (e.g. protozoa, bacteria) to macroparasites (e.g. helminths, parasitic copepods) and discuss the effects of spatial scale on heterogeneities in infection levels. We then demonstrate how parasites can affect host population dynamics by acting as a strong mortality factor, causing mollusc mass mortalities. In addition, we will exemplify how parasites can mediate the interaction strength of predator-prey relationships and affect the topological structure of the Wadden Sea food web as a whole. Finally, we highlight some ongoing changes regarding parasitism in the Wadden Sea in the course of global change (e.g. species introduction, climate change) and identify important future research questions to entangle the role of parasites in the Wadden Sea food web.

  5. Food Web Response to Habitat Restoration in Various Coastal Wetland Ecosystems

    Science.gov (United States)

    James, W. R.; Nelson, J. A.

    2017-12-01

    Coastal wetland habitats provide important ecosystem services, including supporting coastal food webs. These habitats are being lost rapidly. To combat the effects of these losses, millions of dollars have been invested to restore these habitats. However, the relationship between restoring habitat and restoring ecosystem functioning is poorly understood. Analyzing energy flow through food web comparisons between restored and natural habitats can give insights into ecosystem functioning. Using published stable isotope values from organisms in restored and natural habitats, we assessed the food web response of habitat restoration in salt marsh, mangrove, sea grass, and algal bed ecosystems. We ran Bayesian mixing models to quantify resource use by consumers and generated habitat specific niche hypervolumes for each ecosystem to assess food web differences between restored and natural habitats. Salt marsh, mangrove, and sea grass ecosystems displayed functional differences between restored and natural habitats. Salt marsh and mangrove food webs varied in the amount of each resource used, while the sea grass food web displayed more variation between individual organisms. The algal bed food web showed little variation between restored and natural habitats.

  6. Characteristics of food industry web sites and "advergames" targeting children.

    Science.gov (United States)

    Culp, Jennifer; Bell, Robert A; Cassady, Diana

    2010-01-01

    To assess the content of food industry Web sites targeting children by describing strategies used to prolong their visits and foster brand loyalty; and to document health-promoting messages on these Web sites. A content analysis was conducted of Web sites advertised on 2 children's networks, Cartoon Network and Nickelodeon. A total of 290 Web pages and 247 unique games on 19 Internet sites were examined. Games, found on 81% of Web sites, were the most predominant promotion strategy used. All games had at least 1 brand identifier, with logos being most frequently used. On average Web sites contained 1 "healthful" message for every 45 exposures to brand identifiers. Food companies use Web sites to extend their television advertising to promote brand loyalty among children. These sites almost exclusively promoted food items high in sugar and fat. Health professionals need to monitor food industry marketing practices used in "new media." Published by Elsevier Inc.

  7. Size-based predictions of food web patterns

    DEFF Research Database (Denmark)

    Zhang, Lai; Hartvig, Martin; Knudsen, Kim

    2014-01-01

    We employ size-based theoretical arguments to derive simple analytic predictions of ecological patterns and properties of natural communities: size-spectrum exponent, maximum trophic level, and susceptibility to invasive species. The predictions are brought about by assuming that an infinite number...... of species are continuously distributed on a size-trait axis. It is, however, an open question whether such predictions are valid for a food web with a finite number of species embedded in a network structure. We address this question by comparing the size-based predictions to results from dynamic food web...... simulations with varying species richness. To this end, we develop a new size- and trait-based food web model that can be simplified into an analytically solvable size-based model. We confirm existing solutions for the size distribution and derive novel predictions for maximum trophic level and invasion...

  8. A concept of food-web structure in organic arable farming systems

    NARCIS (Netherlands)

    Smeding, F.W.; Snoo, de G.R.

    2003-01-01

    A proposal for a descriptive or topological farm food web is derived from field observations and from references in literature. Important themes in the food-web theory are tentatively applied to this preliminary model, explaining differences between local farm food-web structures and how they are

  9. DEEPWATER AND NEARSHORE FOOD WEB CHARACTERIZATIONS IN LAKE SUPERIOR

    Science.gov (United States)

    Due to the difficulty associated with sampling deep aquatic systems, food web relationships among deepwater fauna are often poorly known. We are characterizing nearshore versus offshore habitats in the Great Lakes and investigating food web linkages among profundal, pelagic, and ...

  10. Changes in host-parasitoid food web structure with elevation.

    Science.gov (United States)

    Maunsell, Sarah C; Kitching, Roger L; Burwell, Chris J; Morris, Rebecca J

    2015-03-01

    Gradients in elevation are increasingly used to investigate how species respond to changes in local climatic conditions. Whilst many studies have shown elevational patterns in species richness and turnover, little is known about how food web structure is affected by elevation. Contrasting responses of predator and prey species to elevation may lead to changes in food web structure. We investigated how the quantitative structure of a herbivore-parasitoid food web changes with elevation in an Australian subtropical rain forest. On four occasions, spread over 1 year, we hand-collected leaf miners at twelve sites, along three elevational gradients (between 493 m and 1159 m a.s.l). A total of 5030 insects, including 603 parasitoids, were reared, and summary food webs were created for each site. We also carried out a replicated manipulative experiment by translocating an abundant leaf-mining weevil Platynotocis sp., which largely escaped parasitism at high elevations (≥ 900 m a.s.l.), to lower, warmer elevations, to test if it would experience higher parasitism pressure. We found strong evidence that the environmental change that occurs with increasing elevation affects food web structure. Quantitative measures of generality, vulnerability and interaction evenness decreased significantly with increasing elevation (and decreasing temperature), whilst elevation did not have a significant effect on connectance. Mined plant composition also had a significant effect on generality and vulnerability, but not on interaction evenness. Several relatively abundant species of leaf miner appeared to escape parasitism at higher elevations, but contrary to our prediction, Platynotocis sp. did not experience greater levels of parasitism when translocated to lower elevations. Our study indicates that leaf-mining herbivores and their parasitoids respond differently to environmental conditions imposed by elevation, thus producing structural changes in their food webs. Increasing

  11. Comparing the Ecological Stoichiometry in Green and Brown Food Webs – A Review and Meta-analysis of Freshwater Food Webs

    Directory of Open Access Journals (Sweden)

    Michelle A. Evans-White

    2017-06-01

    Full Text Available The framework of ecological stoichiometry was developed primarily within the context of “green” autotroph-based food webs. While stoichiometric principles also apply in “brown” detritus-based systems, these systems have been historically understudied and differ from green ones in several important aspects including carbon (C quality and the nutrient [nitrogen (N and phosphorus (P] contents of food resources for consumers. In this paper, we review work over the last decade that has advanced the application of ecological stoichiometry from green to brown food webs, focusing on freshwater ecosystems. We first review three focal areas where green and brown food webs differ: (1 bottom–up controls by light and nutrient availability, (2 stoichiometric constraints on consumer growth and nutritional regulation, and (3 patterns in consumer-driven nutrient dynamics. Our review highlights the need for further study of how light and nutrient availability affect autotroph–heterotroph interactions on detritus and the subsequent effects on consumer feeding and growth. To complement this conceptual review, we formally quantified differences in stoichiometric principles between green and brown food webs using a meta-analysis across feeding studies of freshwater benthic invertebrates. From 257 datasets collated across 46 publications and several unpublished studies, we compared effect sizes (Pearson’s r of resource N:C and P:C on growth, consumption, excretion, and egestion between herbivorous and detritivorous consumers. The meta-analysis revealed that both herbivore and detritivore growth are limited by resource N:C and P:C contents, but effect sizes only among detritivores were significantly above zero. Consumption effect sizes were negative among herbivores but positive for detritivores in the case of both N:C and P:C, indicating distinct compensatory feeding responses across resource stoichiometry gradients. Herbivore P excretion rates responded

  12. Food-web structure of seagrass communities across different spatial scales and human impacts.

    Science.gov (United States)

    Coll, Marta; Schmidt, Allison; Romanuk, Tamara; Lotze, Heike K

    2011-01-01

    Seagrass beds provide important habitat for a wide range of marine species but are threatened by multiple human impacts in coastal waters. Although seagrass communities have been well-studied in the field, a quantification of their food-web structure and functioning, and how these change across space and human impacts has been lacking. Motivated by extensive field surveys and literature information, we analyzed the structural features of food webs associated with Zostera marina across 16 study sites in 3 provinces in Atlantic Canada. Our goals were to (i) quantify differences in food-web structure across local and regional scales and human impacts, (ii) assess the robustness of seagrass webs to simulated species loss, and (iii) compare food-web structure in temperate Atlantic seagrass beds with those of other aquatic ecosystems. We constructed individual food webs for each study site and cumulative webs for each province and the entire region based on presence/absence of species, and calculated 16 structural properties for each web. Our results indicate that food-web structure was similar among low impact sites across regions. With increasing human impacts associated with eutrophication, however, food-web structure show evidence of degradation as indicated by fewer trophic groups, lower maximum trophic level of the highest top predator, fewer trophic links connecting top to basal species, higher fractions of herbivores and intermediate consumers, and higher number of prey per species. These structural changes translate into functional changes with impacted sites being less robust to simulated species loss. Temperate Atlantic seagrass webs are similar to a tropical seagrass web, yet differed from other aquatic webs, suggesting consistent food-web characteristics across seagrass ecosystems in different regions. Our study illustrates that food-web structure and functioning of seagrass habitats change with human impacts and that the spatial scale of food-web analysis

  13. Food-web structure of seagrass communities across different spatial scales and human impacts.

    Directory of Open Access Journals (Sweden)

    Marta Coll

    Full Text Available Seagrass beds provide important habitat for a wide range of marine species but are threatened by multiple human impacts in coastal waters. Although seagrass communities have been well-studied in the field, a quantification of their food-web structure and functioning, and how these change across space and human impacts has been lacking. Motivated by extensive field surveys and literature information, we analyzed the structural features of food webs associated with Zostera marina across 16 study sites in 3 provinces in Atlantic Canada. Our goals were to (i quantify differences in food-web structure across local and regional scales and human impacts, (ii assess the robustness of seagrass webs to simulated species loss, and (iii compare food-web structure in temperate Atlantic seagrass beds with those of other aquatic ecosystems. We constructed individual food webs for each study site and cumulative webs for each province and the entire region based on presence/absence of species, and calculated 16 structural properties for each web. Our results indicate that food-web structure was similar among low impact sites across regions. With increasing human impacts associated with eutrophication, however, food-web structure show evidence of degradation as indicated by fewer trophic groups, lower maximum trophic level of the highest top predator, fewer trophic links connecting top to basal species, higher fractions of herbivores and intermediate consumers, and higher number of prey per species. These structural changes translate into functional changes with impacted sites being less robust to simulated species loss. Temperate Atlantic seagrass webs are similar to a tropical seagrass web, yet differed from other aquatic webs, suggesting consistent food-web characteristics across seagrass ecosystems in different regions. Our study illustrates that food-web structure and functioning of seagrass habitats change with human impacts and that the spatial scale of

  14. Land use alters the resistance and resilience of soil food webs to drought

    Science.gov (United States)

    de Vries, Franciska T.; Liiri, Mira E.; Bjørnlund, Lisa; Bowker, Matthew A.; Christensen, Søren; Setälä, Heikki; Bardgett, Richard D.

    2012-01-01

    Soils deliver several ecosystem services including carbon sequestration and nutrient cycling, which are of central importance to climate mitigation and sustainable food production. Soil biota play an important role in carbon and nitrogen cycling, and, although the effects of land use on soil food webs are well documented the consequences for their resistance and resilience to climate change are not known. We compared the resistance and resilience to drought--which is predicted to increase under climate change of soil food webs of two common land-use systems: intensively managed wheat with a bacterial-based soil food web and extensively managed grassland with a fungal-based soil food web. We found that the fungal-based food web, and the processes of C and N loss it governs, of grassland soil was more resistant, although not resilient, and better able to adapt to drought than the bacterial-based food web of wheat soil. Structural equation modelling revealed that fungal-based soil food webs and greater microbial evenness mitigated C and N loss. Our findings show that land use strongly affects the resistance and resilience of soil food webs to climate change, and that extensively managed grassland promotes more resistant, and adaptable, fungal-based soil food webs.

  15. Medical Device Recalls in Radiation Oncology: Analysis of US Food and Drug Administration Data, 2002-2015.

    Science.gov (United States)

    Connor, Michael J; Tringale, Kathryn; Moiseenko, Vitali; Marshall, Deborah C; Moore, Kevin; Cervino, Laura; Atwood, Todd; Brown, Derek; Mundt, Arno J; Pawlicki, Todd; Recht, Abram; Hattangadi-Gluth, Jona A

    2017-06-01

    To analyze all recalls involving radiation oncology devices (RODs) from the US Food and Drug Administration (FDA)'s recall database, comparing these with non-radiation oncology device recalls to identify discipline-specific trends that may inform improvements in device safety. Recall data on RODs from 2002 to 2015 were sorted into 4 product categories (external beam, brachytherapy, planning systems, and simulation systems). Outcomes included determined cause of recall, recall class (severity), quantity in commerce, time until recall termination (date FDA determines recall is complete), and time since 510(k) approval. Descriptive statistics were performed with linear regression of time-series data. Results for RODs were compared with those for other devices by Pearson χ 2 test for categorical data and 2-sample Kolmogorov-Smirnov test for distributions. There were 502 ROD recalls and 9534 other class II device recalls during 2002 to 2015. Most recalls were for external beam devices (66.7%) and planning systems (22.9%), and recall events peaked in 2011. Radiation oncology devices differed significantly from other devices in all recall outcomes (P≤.04). Recall cause was commonly software related (49% vs 10% for other devices). Recall severity was more often moderate among RODs (97.6% vs 87.2%) instead of severe (0.2% vs 4.4%; Panalysis of recall data can identify areas for device improvement, such as better system design among RODs. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Modelling food-web mediated effects of hydrological variability and environmental flows.

    Science.gov (United States)

    Robson, Barbara J; Lester, Rebecca E; Baldwin, Darren S; Bond, Nicholas R; Drouart, Romain; Rolls, Robert J; Ryder, Darren S; Thompson, Ross M

    2017-11-01

    Environmental flows are designed to enhance aquatic ecosystems through a variety of mechanisms; however, to date most attention has been paid to the effects on habitat quality and life-history triggers, especially for fish and vegetation. The effects of environmental flows on food webs have so far received little attention, despite food-web thinking being fundamental to understanding of river ecosystems. Understanding environmental flows in a food-web context can help scientists and policy-makers better understand and manage outcomes of flow alteration and restoration. In this paper, we consider mechanisms by which flow variability can influence and alter food webs, and place these within a conceptual and numerical modelling framework. We also review the strengths and weaknesses of various approaches to modelling the effects of hydrological management on food webs. Although classic bioenergetic models such as Ecopath with Ecosim capture many of the key features required, other approaches, such as biogeochemical ecosystem modelling, end-to-end modelling, population dynamic models, individual-based models, graph theory models, and stock assessment models are also relevant. In many cases, a combination of approaches will be useful. We identify current challenges and new directions in modelling food-web responses to hydrological variability and environmental flow management. These include better integration of food-web and hydraulic models, taking physiologically-based approaches to food quality effects, and better representation of variations in space and time that may create ecosystem control points. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  17. [Research progress on food sources and food web structure of wetlands based on stable isotopes].

    Science.gov (United States)

    Chen, Zhan Yan; Wu, Hai Tao; Wang, Yun Biao; Lyu, Xian Guo

    2017-07-18

    The trophic dynamics of wetland organisms is the basis of assessing wetland structure and function. Stable isotopes of carbon and nitrogen have been widely applied to identify trophic relationships in food source, food composition and food web transport in wetland ecosystem studies. This paper provided an overall review about the current methodology of isotope mixing model and trophic level in wetland ecosystems, and discussed the standards of trophic fractionation and baseline. Moreover, we characterized the typical food sources and isotopic compositions of wetland ecosystems, summarized the food sources in different trophic levels of herbivores, omnivores and carnivores based on stable isotopic analyses. We also discussed the limitations of stable isotopes in tra-cing food sources and in constructing food webs. Based on the current results, development trends and upcoming requirements, future studies should focus on sample treatment, conservation and trophic enrichment measurement in the wetland food web, as well as on combing a variety of methodologies including traditional stomach stuffing, molecular markers, and multiple isotopes.

  18. Divergent composition but similar function of soil food webs of individual plants

    DEFF Research Database (Denmark)

    Bezemer, T M; Fountain, M T; Barea, J M

    2010-01-01

    food webs were influenced both by the species identity of the plant individual and the surrounding plant community. Unexpectedly, plant identity had the strongest effects on decomposing soil organisms, widely believed to be generalist feeders. In contrast, quantitative food web modeling showed...... that the composition of the plant community influenced nitrogen mineralization under individual plants, but that plant species identity did not affect nitrogen or carbon mineralization or food web stability. Hence, the composition and structure of entire soil food webs vary at the scale of individual plants...... and are strongly influenced by the species identity of the plant. However, the ecosystem functions these food webs provide are determined by the identity of the entire plant community....

  19. Integrating Ecosystem Engineering and Food Web Ecology: Testing the Effect of Biogenic Reefs on the Food Web of a Soft-Bottom Intertidal Area.

    Science.gov (United States)

    De Smet, Bart; Fournier, Jérôme; De Troch, Marleen; Vincx, Magda; Vanaverbeke, Jan

    2015-01-01

    The potential of ecosystem engineers to modify the structure and dynamics of food webs has recently been hypothesised from a conceptual point of view. Empirical data on the integration of ecosystem engineers and food webs is however largely lacking. This paper investigates the hypothesised link based on a field sampling approach of intertidal biogenic aggregations created by the ecosystem engineer Lanice conchilega (Polychaeta, Terebellidae). The aggregations are known to have a considerable impact on the physical and biogeochemical characteristics of their environment and subsequently on the abundance and biomass of primary food sources and the macrofaunal (i.e. the macro-, hyper- and epibenthos) community. Therefore, we hypothesise that L. conchilega aggregations affect the structure, stability and isotopic niche of the consumer assemblage of a soft-bottom intertidal food web. Primary food sources and the bentho-pelagic consumer assemblage of a L. conchilega aggregation and a control area were sampled on two soft-bottom intertidal areas along the French coast and analysed for their stable isotopes. Despite the structural impacts of the ecosystem engineer on the associated macrofaunal community, the presence of L. conchilega aggregations only has a minor effect on the food web structure of soft-bottom intertidal areas. The isotopic niche width of the consumer communities of the L. conchilega aggregations and control areas are highly similar, implying that consumer taxa do not shift their diet when feeding in a L. conchilega aggregation. Besides, species packing and hence trophic redundancy were not affected, pointing to an unaltered stability of the food web in the presence of L. conchilega.

  20. Eelgrass (Zostera marina) food web structure in different environmental settings

    DEFF Research Database (Denmark)

    Thormar, Jonas Gjaldbæk; Hasler-Sheetal, Harald; Baden, Susanne

    2016-01-01

    his study compares the structure of eelgrass (Zostera marina L.) meadows and associated food webs in two eelgrass habitats in Denmark, differing in exposure, connection to the open sea, nutrient enrichment and water transparency. Meadow structure strongly reflected the environmental conditions...... composition and food web structure also differed markedly between sites with the eutrophicated, enclosed site having higher biomass of consumers and less complex food web. These relationships resulted in a column shaped biomass distribution of the consumers at the eutrophicated site whereas the less nutrient...

  1. The Food Web of Potter Cove (Antarctica): complexity, structure and function

    Science.gov (United States)

    Marina, Tomás I.; Salinas, Vanesa; Cordone, Georgina; Campana, Gabriela; Moreira, Eugenia; Deregibus, Dolores; Torre, Luciana; Sahade, Ricardo; Tatián, Marcos; Barrera Oro, Esteban; De Troch, Marleen; Doyle, Santiago; Quartino, María Liliana; Saravia, Leonardo A.; Momo, Fernando R.

    2018-01-01

    Knowledge of the food web structure and complexity are central to better understand ecosystem functioning. A food-web approach includes both species and energy flows among them, providing a natural framework for characterizing species' ecological roles and the mechanisms through which biodiversity influences ecosystem dynamics. Here we present for the first time a high-resolution food web for a marine ecosystem at Potter Cove (northern Antarctic Peninsula). Eleven food web properties were analyzed in order to document network complexity, structure and topology. We found a low linkage density (3.4), connectance (0.04) and omnivory percentage (45), as well as a short path length (1.8) and a low clustering coefficient (0.08). Furthermore, relating the structure of the food web to its dynamics, an exponential degree distribution (in- and out-links) was found. This suggests that the Potter Cove food web may be vulnerable if the most connected species became locally extinct. For two of the three more connected functional groups, competition overlap graphs imply high trophic interaction between demersal fish and niche specialization according to feeding strategies in amphipods. On the other hand, the prey overlap graph shows also that multiple energy pathways of carbon flux exist across benthic and pelagic habitats in the Potter Cove ecosystem. Although alternative food sources might add robustness to the web, network properties (low linkage density, connectance and omnivory) suggest fragility and potential trophic cascade effects.

  2. Insect symbionts in food webs

    Czech Academy of Sciences Publication Activity Database

    McLean, A. H. C.; Parker, B. J.; Hrček, Jan; Henry, L. M.; Godfray, H. C. J.

    2016-01-01

    Roč. 371, č. 1702 (2016), article number 20150325 ISSN 0962-8436 Institutional support: RVO:60077344 Keywords : food web * symbiont * symbiosis Subject RIV: EE - Microbiology, Virology Impact factor: 5.846, year: 2016 http://rstb.royalsocietypublishing.org/content/371/1702/20150325

  3. Caught in the food web: complexity made simple?

    Directory of Open Access Journals (Sweden)

    Lawrence R. Pomeroy

    2001-12-01

    Full Text Available Several historically separate lines of food-web research are merging into a unified approach. Connections between microbial and metazoan food webs are significant. Interactions of control by predators, defenses against predation, and availability of organic and inorganic nutrition, not any one of these, shape food webs. The same principles of population ecology apply to metazoans and microorganisms, but microorganisms dominate the flux of energy in both marine and terrestrial systems. Microbial biomass often is a major fraction of total biomass, and very small organisms have a very large ratio of production and respiration to biomass. Assimilation efficiency of bacteria in natural systems is often not as high as in experimental systems, so more primary production is lost to microbial respiration than had been thought. Simulation has been a highly useful adjunct to experiments in both population theory and in studies of biogeochemical mass balance, but it does not fully encompass the complexity of real systems. A major challenge for the future is to find better ways to deal with the real complexity of food webs, both in modeling and in empirical observations, and to do a better job of bringing together conceptually the dynamics of population processes and biogeochemistry.

  4. Modelling PCB bioaccumulation in a Baltic food web

    International Nuclear Information System (INIS)

    Nfon, Erick; Cousins, Ian T.

    2007-01-01

    A steady state model is developed to describe the bioaccumulation of organic contaminants by 14 species in a Baltic food web including pelagic and benthic aquatic organisms. The model is used to study the bioaccumulation of five PCB congeners of different chlorination levels. The model predictions are evaluated against monitoring data for five of the species in the food web. Predicted concentrations are on average within a factor of two of measured concentrations. The model shows that all PCB congeners were biomagnified in the food web, which is consistent with observations. Sensitivity analysis reveals that the single most sensitive parameter is log K OW . The most sensitive environmental parameter is the annual average temperature. Although not identified amongst the most sensitive input parameters, the dissolved concentration in water is believed to be important because of the uncertainty in its determination. The most sensitive organism-specific input parameters are the fractional respiration of species from the water column and sediment pore water, which are also difficult to determine. Parameters such as feeding rate, growth rate and lipid content of organism are only important at higher trophic levels. - The bioaccumulation behaviour of PCB congeners in a Baltic food web is studied using a novel mechanistic model

  5. Medical Device Recalls in Radiation Oncology: Analysis of US Food and Drug Administration Data, 2002-2015

    International Nuclear Information System (INIS)

    Connor, Michael J.; Tringale, Kathryn; Moiseenko, Vitali; Marshall, Deborah C.; Moore, Kevin; Cervino, Laura; Atwood, Todd; Brown, Derek; Mundt, Arno J.; Pawlicki, Todd; Recht, Abram; Hattangadi-Gluth, Jona A.

    2017-01-01

    Purpose: To analyze all recalls involving radiation oncology devices (RODs) from the US Food and Drug Administration (FDA)'s recall database, comparing these with non–radiation oncology device recalls to identify discipline-specific trends that may inform improvements in device safety. Methods and Materials: Recall data on RODs from 2002 to 2015 were sorted into 4 product categories (external beam, brachytherapy, planning systems, and simulation systems). Outcomes included determined cause of recall, recall class (severity), quantity in commerce, time until recall termination (date FDA determines recall is complete), and time since 510(k) approval. Descriptive statistics were performed with linear regression of time-series data. Results for RODs were compared with those for other devices by Pearson χ"2 test for categorical data and 2-sample Kolmogorov-Smirnov test for distributions. Results: There were 502 ROD recalls and 9534 other class II device recalls during 2002 to 2015. Most recalls were for external beam devices (66.7%) and planning systems (22.9%), and recall events peaked in 2011. Radiation oncology devices differed significantly from other devices in all recall outcomes (P≤.04). Recall cause was commonly software related (49% vs 10% for other devices). Recall severity was more often moderate among RODs (97.6% vs 87.2%) instead of severe (0.2% vs 4.4%; P<.001). Time from 510(k) market approval to recall was shorter among RODs (P<.001) and progressively shortened over time. Radiation oncology devices had fewer recalled devices in commerce than other devices (P<.001). Conclusions: Compared with other class II devices, RODs experience recalls sooner after market approval and are trending sooner still. Most of these recalls were moderate in severity, and software issues are prevalent. Comprehensive analysis of recall data can identify areas for device improvement, such as better system design among RODs.

  6. Medical Device Recalls in Radiation Oncology: Analysis of US Food and Drug Administration Data, 2002-2015

    Energy Technology Data Exchange (ETDEWEB)

    Connor, Michael J. [Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California (United States); University of California Irvine School of Medicine, Irvine, California (United States); Tringale, Kathryn; Moiseenko, Vitali; Marshall, Deborah C.; Moore, Kevin; Cervino, Laura; Atwood, Todd; Brown, Derek; Mundt, Arno J.; Pawlicki, Todd [Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California (United States); Recht, Abram [Department of Radiation Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts (United States); Hattangadi-Gluth, Jona A., E-mail: jhattangadi@ucsd.edu [Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, California (United States)

    2017-06-01

    Purpose: To analyze all recalls involving radiation oncology devices (RODs) from the US Food and Drug Administration (FDA)'s recall database, comparing these with non–radiation oncology device recalls to identify discipline-specific trends that may inform improvements in device safety. Methods and Materials: Recall data on RODs from 2002 to 2015 were sorted into 4 product categories (external beam, brachytherapy, planning systems, and simulation systems). Outcomes included determined cause of recall, recall class (severity), quantity in commerce, time until recall termination (date FDA determines recall is complete), and time since 510(k) approval. Descriptive statistics were performed with linear regression of time-series data. Results for RODs were compared with those for other devices by Pearson χ{sup 2} test for categorical data and 2-sample Kolmogorov-Smirnov test for distributions. Results: There were 502 ROD recalls and 9534 other class II device recalls during 2002 to 2015. Most recalls were for external beam devices (66.7%) and planning systems (22.9%), and recall events peaked in 2011. Radiation oncology devices differed significantly from other devices in all recall outcomes (P≤.04). Recall cause was commonly software related (49% vs 10% for other devices). Recall severity was more often moderate among RODs (97.6% vs 87.2%) instead of severe (0.2% vs 4.4%; P<.001). Time from 510(k) market approval to recall was shorter among RODs (P<.001) and progressively shortened over time. Radiation oncology devices had fewer recalled devices in commerce than other devices (P<.001). Conclusions: Compared with other class II devices, RODs experience recalls sooner after market approval and are trending sooner still. Most of these recalls were moderate in severity, and software issues are prevalent. Comprehensive analysis of recall data can identify areas for device improvement, such as better system design among RODs.

  7. Theory of invasion extinction dynamics in minimal food webs

    Science.gov (United States)

    Haerter, Jan O.; Mitarai, Namiko; Sneppen, Kim

    2018-02-01

    When food webs are exposed to species invasion, secondary extinction cascades may be set off. Although much work has gone into characterizing the structure of food webs, systematic predictions on their evolutionary dynamics are still scarce. Here we present a theoretical framework that predicts extinctions in terms of an alternating sequence of two basic processes: resource depletion by or competitive exclusion between consumers. We first propose a conceptual invasion extinction model (IEM) involving random fitness coefficients. We bolster this IEM by an analytical, recursive procedure for calculating idealized extinction cascades after any species addition and simulate the long-time evolution. Our procedure describes minimal food webs where each species interacts with only a single resource through the generalized Lotka-Volterra equations. For such food webs ex- tinction cascades are determined uniquely and the system always relaxes to a stable steady state. The dynamics and scale invariant species life time resemble the behavior of the IEM, and correctly predict an upper limit for trophic levels as observed in the field.

  8. Towards ecosystem-based management: Identifying operational food-web indicators for marine ecosystems

    DEFF Research Database (Denmark)

    Tam, Jamie C.; Link, Jason S.; Rossberg, Axel G.

    2017-01-01

    ) are an important aspect of all marine ecosystems and biodiversity. Here we describe and discuss a process to evaluate the selection of operational food-web indicators for use in evaluating marine ecosystem status. This process brought together experts in food-web ecology, marine ecology, and resource management......, to identify available indicators that can be used to inform marine management. Standard evaluation criteria (availability and quality of data, conceptual basis, communicability, relevancy to management) were implemented to identify practical food-web indicators ready for operational use and indicators...... that hold promise for future use in policy and management. The major attributes of the final suite of operational food-web indicators were structure and functioning. Indicators that represent resilience of the marine ecosystem were less developed. Over 60 potential food-web indicators were evaluated...

  9. Interactive effects of body-size structure and adaptive foraging on food-web stability.

    Science.gov (United States)

    Heckmann, Lotta; Drossel, Barbara; Brose, Ulrich; Guill, Christian

    2012-03-01

    Body-size structure of food webs and adaptive foraging of consumers are two of the dominant concepts of our understanding how natural ecosystems maintain their stability and diversity. The interplay of these two processes, however, is a critically important yet unresolved issue. To fill this gap in our knowledge of ecosystem stability, we investigate dynamic random and niche model food webs to evaluate the proportion of persistent species. We show that stronger body-size structures and faster adaptation stabilise these food webs. Body-size structures yield stabilising configurations of interaction strength distributions across food webs, and adaptive foraging emphasises links to resources closer to the base. Moreover, both mechanisms combined have a cumulative effect. Most importantly, unstructured random webs evolve via adaptive foraging into stable size-structured food webs. This offers a mechanistic explanation of how size structure adaptively emerges in complex food webs, thus building a novel bridge between these two important stabilising mechanisms. © 2012 Blackwell Publishing Ltd/CNRS.

  10. Food web heterogeneity and succession in created saltmarshes

    Science.gov (United States)

    Nordstrom, M C; Demopoulos, Amanda W.J.; Whitcraft, CR; Rismondo, A.; McMillan, P.; Gonzales, J P; Levin, L A

    2015-01-01

    1. Ecological restoration must achieve functional as well as structural recovery. Functional metrics for reestablishment of trophic interactions can be used to complement traditional monitoring of structural attributes. In addition, topographic effects on food web structure provide added information within a restoration context; often, created sites may require spatial heterogeneity to effectively match structure and function of natural habitats. 2. We addressed both of these issues in our study of successional development of benthic food web structure, with focus on bottom–up driven changes in macroinvertebrate consumer assemblages in the salt marshes of the Venice Lagoon, Italy. We combined quantified estimates of the changing community composition with stable isotope data (13C:12C and 15N:14N) to compare the general trophic structure between created (2–14 years) marshes and reference sites and along topographic elevation gradients within salt marshes. 3. Macrofaunal invertebrate consumers exhibited local, habitat-specific trophic patterns. Stable isotope-based trophic structure changed with increasing marsh age, in particular with regards to mid-elevation (Salicornia) habitats. In young marshes, the mid-elevation consumer signatures resembled those of unvegetated ponds. The mid elevation of older and natural marshes had a more distinct Salicornia-zone food web, occasionally resembling that of the highest (Sarcocornia-dominated) elevation. In summary, this indicates that primary producers and availability of vascular plant detritus structure consumer trophic interactions and the flow of carbon. 4. Functionally different consumers, subsurface-feeding detritivores (Oligochaeta) and surface grazers (Hydrobia sp.), showed distinct but converging trajectories of isotopic change over time, indicating that successional development may be asymmetric between ‘brown’ (detrital) guilds and ‘green’ (grazing) guilds in the food web. 5. Synthesis and applications

  11. Food-web dynamics under climate change

    DEFF Research Database (Denmark)

    Zhang, L.; Takahashi, M.; Hartvig, Martin

    2017-01-01

    Climate change affects ecological communities through its impact on the physiological performance of individuals. However, the population dynamic of species well inside their thermal niche is also determined by competitors, prey and predators, in addition to being influenced by temperature changes....... We use a trait-based food-web model to examine how the interplay between the direct physiological effects from temperature and the indirect effects due to changing interactions between populations shapes the ecological consequences of climate change for populations and for entire communities. Our...... climatically well-adapted species may be brought to extinction by the changed food-web topology. Our results highlight that the impact of climate change on specific populations is largely unpredictable, and apparently well-adapted species may be severely impacted...

  12. Assimilation of diazotrophic nitrogen into pelagic food webs.

    Science.gov (United States)

    Woodland, Ryan J; Holland, Daryl P; Beardall, John; Smith, Jonathan; Scicluna, Todd; Cook, Perran L M

    2013-01-01

    The fate of diazotrophic nitrogen (N(D)) fixed by planktonic cyanobacteria in pelagic food webs remains unresolved, particularly for toxic cyanophytes that are selectively avoided by most herbivorous zooplankton. Current theory suggests that N(D) fixed during cyanobacterial blooms can enter planktonic food webs contemporaneously with peak bloom biomass via direct grazing of zooplankton on cyanobacteria or via the uptake of bioavailable N(D) (exuded from viable cyanobacterial cells) by palatable phytoplankton or microbial consortia. Alternatively, N(D) can enter planktonic food webs post-bloom following the remineralization of bloom detritus. Although the relative contribution of these processes to planktonic nutrient cycles is unknown, we hypothesized that assimilation of bioavailable N(D) (e.g., nitrate, ammonium) by palatable phytoplankton and subsequent grazing by zooplankton (either during or after the cyanobacterial bloom) would be the primary pathway by which N(D) was incorporated into the planktonic food web. Instead, in situ stable isotope measurements and grazing experiments clearly documented that the assimilation of N(D) by zooplankton outpaced assimilation by palatable phytoplankton during a bloom of toxic Nodularia spumigena Mertens. We identified two distinct temporal phases in the trophic transfer of N(D) from N. spumigena to the plankton community. The first phase was a highly dynamic transfer of N(D) to zooplankton with rates that covaried with bloom biomass while bypassing other phytoplankton taxa; a trophic transfer that we infer was routed through bloom-associated bacteria. The second phase was a slowly accelerating assimilation of the dissolved-N(D) pool by phytoplankton that was decoupled from contemporaneous variability in N. spumigena concentrations. These findings provide empirical evidence that N(D) can be assimilated and transferred rapidly throughout natural plankton communities and yield insights into the specific processes underlying

  13. Assimilation of diazotrophic nitrogen into pelagic food webs.

    Directory of Open Access Journals (Sweden)

    Ryan J Woodland

    Full Text Available The fate of diazotrophic nitrogen (N(D fixed by planktonic cyanobacteria in pelagic food webs remains unresolved, particularly for toxic cyanophytes that are selectively avoided by most herbivorous zooplankton. Current theory suggests that N(D fixed during cyanobacterial blooms can enter planktonic food webs contemporaneously with peak bloom biomass via direct grazing of zooplankton on cyanobacteria or via the uptake of bioavailable N(D (exuded from viable cyanobacterial cells by palatable phytoplankton or microbial consortia. Alternatively, N(D can enter planktonic food webs post-bloom following the remineralization of bloom detritus. Although the relative contribution of these processes to planktonic nutrient cycles is unknown, we hypothesized that assimilation of bioavailable N(D (e.g., nitrate, ammonium by palatable phytoplankton and subsequent grazing by zooplankton (either during or after the cyanobacterial bloom would be the primary pathway by which N(D was incorporated into the planktonic food web. Instead, in situ stable isotope measurements and grazing experiments clearly documented that the assimilation of N(D by zooplankton outpaced assimilation by palatable phytoplankton during a bloom of toxic Nodularia spumigena Mertens. We identified two distinct temporal phases in the trophic transfer of N(D from N. spumigena to the plankton community. The first phase was a highly dynamic transfer of N(D to zooplankton with rates that covaried with bloom biomass while bypassing other phytoplankton taxa; a trophic transfer that we infer was routed through bloom-associated bacteria. The second phase was a slowly accelerating assimilation of the dissolved-N(D pool by phytoplankton that was decoupled from contemporaneous variability in N. spumigena concentrations. These findings provide empirical evidence that N(D can be assimilated and transferred rapidly throughout natural plankton communities and yield insights into the specific processes

  14. Functional redundancy and food web functioning in linuron-exposed ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    De Laender, F., E-mail: frederik.delaender@ugent.be [Laboratory of Environmental Toxicity and Aquatic Ecology, Ghent University, Plateaustraat 22, 9000 Ghent (Belgium); Van den Brink, P.J., E-mail: Paul.vandenBrink@wur.nl [Department of Aquatic Ecology and Water Quality Management, Wageningen University, PO Box 47, 6700 AA Wageningen (Netherlands); Janssen, C.R., E-mail: colin.janssen@ugent.be [Laboratory of Environmental Toxicity and Aquatic Ecology, Ghent University, Plateaustraat 22, 9000 Ghent (Belgium)

    2011-10-15

    An extensive data set describing effects of the herbicide linuron on macrophyte-dominated microcosms was analysed with a food web model to assess effects on ecosystem functioning. We showed that sensitive phytoplankton and periphyton groups in the diets of heterotrophs were gradually replaced by more tolerant phytoplankton species as linuron concentrations increased. This diet shift - showing redundancy among phytoplankton species - allowed heterotrophs to maintain their functions in the contaminated microcosms. On an ecosystem level, total gross primary production was up to hundred times lower in the treated microcosms but the uptake of dissolved organic carbon by bacteria and mixotrophs was less sensitive. Food web efficiency was not consistently lower in the treated microcosms. We conclude that linuron predominantly affected the macrophytes but did not alter the overall functioning of the surrounding planktonic food web. Therefore, a risk assessment that protects macrophyte growth also protects the functioning of macrophyte-dominated microcosms. - Highlights: > Food web modelling reveals the functional response of species and ecosystem to linuron. > Primary production was more sensitive to linuron than bacterial production. > Linuron replaced sensitive phytoplankton by tolerant phytoplankton in heterotrophs' diets. > Linuron did not change the functioning of heterotrophs. - Food web modelling reveals functional redundancy of the planktonic community in microcosms treated with linuron.

  15. Functional redundancy and food web functioning in linuron-exposed ecosystems

    International Nuclear Information System (INIS)

    De Laender, F.; Van den Brink, P.J.; Janssen, C.R.

    2011-01-01

    An extensive data set describing effects of the herbicide linuron on macrophyte-dominated microcosms was analysed with a food web model to assess effects on ecosystem functioning. We showed that sensitive phytoplankton and periphyton groups in the diets of heterotrophs were gradually replaced by more tolerant phytoplankton species as linuron concentrations increased. This diet shift - showing redundancy among phytoplankton species - allowed heterotrophs to maintain their functions in the contaminated microcosms. On an ecosystem level, total gross primary production was up to hundred times lower in the treated microcosms but the uptake of dissolved organic carbon by bacteria and mixotrophs was less sensitive. Food web efficiency was not consistently lower in the treated microcosms. We conclude that linuron predominantly affected the macrophytes but did not alter the overall functioning of the surrounding planktonic food web. Therefore, a risk assessment that protects macrophyte growth also protects the functioning of macrophyte-dominated microcosms. - Highlights: → Food web modelling reveals the functional response of species and ecosystem to linuron. → Primary production was more sensitive to linuron than bacterial production. → Linuron replaced sensitive phytoplankton by tolerant phytoplankton in heterotrophs' diets. → Linuron did not change the functioning of heterotrophs. - Food web modelling reveals functional redundancy of the planktonic community in microcosms treated with linuron.

  16. Adaptive foraging and flexible food web topology

    Czech Academy of Sciences Publication Activity Database

    Křivan, Vlastimil; Schmitz, O.

    2003-01-01

    Roč. 5, - (2003), s. 623-652 ISSN 1522-0613 R&D Projects: GA ČR GA201/03/0091 Institutional research plan: CEZ:AV0Z5007907 Keywords : adaptive foraging * food chain * food web structure Subject RIV: EH - Ecology, Behaviour Impact factor: 1.587, year: 2003

  17. Gaining insight into food webs reconstructed by the inverse method

    NARCIS (Netherlands)

    Kones, J.; Soetaert, K.E.R.; Van Oevelen, D.; Owino, J.; Mavuti, K.

    2006-01-01

    The use of the inverse method to analyze flow patterns of organic components in ecological systems has had wide application in ecological modeling. Through this approach, an infinite number of food web flows describing the food web and satisfying biological constraints are generated, from which one

  18. Key features of intertidal food webs that support migratory shorebirds.

    Directory of Open Access Journals (Sweden)

    Blanche Saint-Béat

    Full Text Available The migratory shorebirds of the East Atlantic flyway land in huge numbers during a migratory stopover or wintering on the French Atlantic coast. The Brouage bare mudflat (Marennes-Oléron Bay, NE Atlantic is one of the major stopover sites in France. The particular structure and function of a food web affects the efficiency of carbon transfer. The structure and functioning of the Brouage food web is crucial for the conservation of species landing within this area because it provides sufficient food, which allows shorebirds to reach the north of Europe where they nest. The aim of this study was to describe and understand which food web characteristics support nutritional needs of birds. Two food-web models were constructed, based on in situ measurements that were made in February 2008 (the presence of birds and July 2008 (absence of birds. To complete the models, allometric relationships and additional data from the literature were used. The missing flow values of the food web models were estimated by Monte Carlo Markov Chain--Linear Inverse Modelling. The flow solutions obtained were used to calculate the ecological network analysis indices, which estimate the emergent properties of the functioning of a food-web. The total activities of the Brouage ecosystem in February and July are significantly different. The specialisation of the trophic links within the ecosystem does not appear to differ between the two models. In spite of a large export of carbon from the primary producer and detritus in winter, the higher recycling leads to a similar retention of carbon for the two seasons. It can be concluded that in February, the higher activity of the ecosystem coupled with a higher cycling and a mean internal organization, ensure the sufficient feeding of the migratory shorebirds.

  19. Existence and construction of large stable food webs

    Science.gov (United States)

    Haerter, Jan O.; Mitarai, Namiko; Sneppen, Kim

    2017-09-01

    Ecological diversity is ubiquitous despite the restrictions imposed by competitive exclusion and apparent competition. To explain the observed richness of species in a given habitat, food-web theory has explored nonlinear functional responses, self-interaction, or spatial structure and dispersal—model ingredients that have proven to promote stability and diversity. We return instead here to classical Lotka-Volterra equations, where species-species interaction is characterized by a simple product and spatial restrictions are ignored. We quantify how this idealization imposes constraints on coexistence and diversity for many species. To this end, we introduce the concept of free and controlled species and use this to demonstrate how stable food webs can be constructed by the sequential addition of species. The resulting food webs can reach dozens of species and generally yield nonrandom degree distributions in accordance with the constraints imposed through the assembly process. Our model thus serves as a formal starting point for the study of sustainable interaction patterns between species.

  20. Understanding soil food web dynamics, how close do we get?

    NARCIS (Netherlands)

    Morriën, E.

    2016-01-01

    Soil food webs are traditionally considered to have distinct energy channels through which resources flow belowground. Resources enter the soil food web either from roots or from detrital inputs. Compared to this traditional view we are now much more aware of the flow of carbon, nitrogen and other

  1. Worldwide food recall patterns over an eleven month period: A country perspective

    Directory of Open Access Journals (Sweden)

    Petróczi Andrea

    2008-09-01

    Full Text Available Abstract Background Following the World Health Organization Forum in November 2007, the Beijing Declaration recognized the importance of food safety along with the rights of all individuals to a safe and adequate diet. The aim of this study is to retrospectively analyze the patterns in food alert and recall by countries to identify the principal hazard generators and gatekeepers of food safety in the eleven months leading up to the Declaration. Methods The food recall data set was collected by the Laboratory of the Government Chemist (LGC, UK over the period from January to November 2007. Statistics were computed with the focus reporting patterns by the 117 countries. The complexity of the recorded interrelations was depicted as a network constructed from structural properties contained in the data. The analysed network properties included degrees, weighted degrees, modularity and k-core decomposition. Network analyses of the reports, based on 'country making report' (detector and 'country reported on' (transgressor, revealed that the network is organized around a dominant core. Results Ten countries were reported for sixty per cent of all faulty products marketed, with the top 5 countries having received between 100 to 281 reports. Further analysis of the dominant core revealed that out of the top five transgressors three made no reports (in the order China > Turkey > Iran. The top ten detectors account for three quarters of reports with three > 300 (Italy: 406, Germany: 340, United Kingdom: 322. Conclusion Of the 117 countries studied, the vast majority of food reports are made by 10 countries, with EU countries predominating. The majority of the faulty foodstuffs originate in ten countries with four major producers making no reports. This pattern is very distant from that proposed by the Beijing Declaration which urges all countries to take responsibility for the provision of safe and adequate diets for their nationals.

  2. Legacy effects of drought on plant growth and the soil food web

    DEFF Research Database (Denmark)

    de Vries, Franciska; Liiri, Mira; Strandmark, Lisa Bjørnlund

    2012-01-01

    the potential to feed back on each other's performance. In a greenhouse experiment, we compared legacy effects of repeated drought on plant growth and the soil food web in two contrasting land-use systems: extensively managed grassland, rich in C and with a fungal-based food web, and intensively managed wheat...... lower in C and with a bacterial-based food web. Moreover, we assessed the effect of plant presence on the recovery of the soil food web after drought. Drought legacy effects increased plant growth in both systems, and a plant strongly reduced N leaching. Fungi, bacteria, and their predators were more...... resilient after drought in the grassland soil than in the wheat soil. The presence of a plant strongly affected the composition of the soil food web, and alleviated the effects of drought for most trophic groups, regardless of the system. This effect was stronger for the bottom trophic levels, whose...

  3. Stable-isotope analysis: a neglected tool for placing parasites in food webs.

    Science.gov (United States)

    Sabadel, A J M; Stumbo, A D; MacLeod, C D

    2018-02-28

    Parasites are often overlooked in the construction of food webs, despite their ubiquitous presence in almost every type of ecosystem. Researchers who do recognize their importance often struggle to include parasites using classical food-web theory, mainly due to the parasites' multiple hosts and life stages. A novel approach using compound-specific stable-isotope analysis promises to provide considerable insight into the energetic exchanges of parasite and host, which may solve some of the issues inherent in incorporating parasites using a classical approach. Understanding the role of parasites within food webs, and tracing the associated biomass transfers, are crucial to constructing new models that will expand our knowledge of food webs. This mini-review focuses on stable-isotope studies published in the past decade, and introduces compound-specific stable-isotope analysis as a powerful, but underutilized, newly developed tool that may answer many unresolved questions regarding the role of parasites in food webs.

  4. Methylmercury biomagnification in an Arctic pelagic food web.

    Science.gov (United States)

    Ruus, Anders; Øverjordet, Ida B; Braaten, Hans Fredrik V; Evenset, Anita; Christensen, Guttorm; Heimstad, Eldbjørg S; Gabrielsen, Geir W; Borgå, Katrine

    2015-11-01

    Mercury (Hg) is a toxic element that enters the biosphere from natural and anthropogenic sources, and emitted gaseous Hg enters the Arctic from lower latitudes by long-range transport. In aquatic systems, anoxic conditions favor the bacterial transformation of inorganic Hg to methylmercury (MeHg), which has a greater potential for bioaccumulation than inorganic Hg and is the most toxic form of Hg. The main objective of the present study was to quantify the biomagnification of MeHg in a marine pelagic food web, comprising species of zooplankton, fish, and seabirds, from the Kongsfjorden system (Svalbard, Norway), by use of trophic magnification factors. As expected, tissue concentrations of MeHg increased with increasing trophic level in the food web, though at greater rates than observed in several earlier studies, especially at lower latitudes. There was strong correlation between MeHg and total Hg concentrations through the food web as a whole. The concentration of MeHg in kittiwake decreased from May to October, contributing to seasonal differences in trophic magnification factors. The ecology and physiology of the species comprising the food web in question may have a large influence on the magnitude of the biomagnification. A significant linear relationship was also observed between concentrations of selenium and total Hg in birds but not in zooplankton, suggesting the importance of selenium in Hg detoxification for individuals with high Hg concentrations. © 2015 SETAC.

  5. Soil food web structure after wood ash application

    DEFF Research Database (Denmark)

    Mortensen, L. H.; Qin, J.; Krogh, Paul Henning

    with varying intervals and subsequently analyzed. The food web analysis includes several trophic levels; bacteria/fungi, protozoa, nematodes, enchytraeids, microarthropods and arthropods. The initial results indicate that bacteria and protozoa are stimulated in the uppermost soil layer (0-3 cm) two months...... can facilitate an increase in the bacteria to fungi ratio with possible cascading effects for the soil food web structure. This is tested by applying ash of different concentrations to experimental plots in a coniferous forest. During the course of the project soil samples will be collected...

  6. River food webs: an integrative approach to bottom-up flow webs, top-down impact webs, and trophic position.

    Science.gov (United States)

    Benke, Arthur C

    2018-03-31

    The majority of food web studies are based on connectivity, top-down impacts, bottom-up flows, or trophic position (TP), and ecologists have argued for decades which is best. Rarely have any two been considered simultaneously. The present study uses a procedure that integrates the last three approaches based on taxon-specific secondary production and gut analyses. Ingestion flows are quantified to create a flow web and the same data are used to quantify TP for all taxa. An individual predator's impacts also are estimated using the ratio of its ingestion (I) of each prey to prey production (P) to create an I/P web. This procedure was applied to 41 invertebrate taxa inhabiting submerged woody habitat in a southeastern U.S. river. A complex flow web starting with five basal food resources had 462 flows >1 mg·m -2 ·yr -1 , providing far more information than a connectivity web. Total flows from basal resources to primary consumers/omnivores were dominated by allochthonous amorphous detritus and ranged from 1 to >50,000 mg·m -2 ·yr -1 . Most predator-prey flows were much lower (1,000  mg·m -2 ·yr -1 . The I/P web showed that 83% of individual predator impacts were weak (90%). Quantitative estimates of TP ranged from 2 to 3.7, contrasting sharply with seven integer-based trophic levels based on longest feeding chain. Traditional omnivores (TP = 2.4-2.9) played an important role by consuming more prey and exerting higher impacts on primary consumers than strict predators (TP ≥ 3). This study illustrates how simultaneous quantification of flow pathways, predator impacts, and TP together provide an integrated characterization of natural food webs. © 2018 by the Ecological Society of America.

  7. Global change in the trophic functioning of marine food webs.

    Directory of Open Access Journals (Sweden)

    Aurore Maureaud

    Full Text Available The development of fisheries in the oceans, and other human drivers such as climate warming, have led to changes in species abundance, assemblages, trophic interactions, and ultimately in the functioning of marine food webs. Here, using a trophodynamic approach and global databases of catches and life history traits of marine species, we tested the hypothesis that anthropogenic ecological impacts may have led to changes in the global parameters defining the transfers of biomass within the food web. First, we developed two indicators to assess such changes: the Time Cumulated Indicator (TCI measuring the residence time of biomass within the food web, and the Efficiency Cumulated Indicator (ECI quantifying the fraction of secondary production reaching the top of the trophic chain. Then, we assessed, at the large marine ecosystem scale, the worldwide change of these two indicators over the 1950-2010 time-periods. Global trends were identified and cluster analyses were used to characterize the variability of trends between ecosystems. Results showed that the most common pattern over the study period is a global decrease in TCI, while the ECI indicator tends to increase. Thus, changes in species assemblages would induce faster and apparently more efficient biomass transfers in marine food webs. Results also suggested that the main driver of change over that period had been the large increase in fishing pressure. The largest changes occurred in ecosystems where 'fishing down the marine food web' are most intensive.

  8. Pulsed flows, tributary inputs, and food web structure in a highly regulated river

    Science.gov (United States)

    Sabo, John; Caron, Melanie; Doucett, Richard R.; Dibble, Kimberly L.; Ruhi, Albert; Marks, Jane; Hungate, Bruce; Kennedy, Theodore A.

    2018-01-01

    1.Dams disrupt the river continuum, altering hydrology, biodiversity, and energy flow. Although research indicates that tributary inputs have the potential to dilute these effects, knowledge at the food web level is still scarce.2.Here we examined the riverine food web structure of the Colorado River below Glen Canyon Dam, focusing on organic matter sources, trophic diversity, and food chain length. We asked how these components respond to pulsed flows from tributaries following monsoon thunderstorms that seasonally increase streamflow in the American Southwest.3.Tributaries increased the relative importance of terrestrial organic matter, particularly during the wet season below junctures of key tributaries. This contrasted with the algal-based food web present immediately below Glen Canyon Dam.4.Tributary inputs during the monsoon also increased trophic diversity and food chain length: food chain length peaked below the confluence with the largest tributary (by discharge) in Grand Canyon, increasing by >1 trophic level over a 4-5 kilometre reach possibly due to aquatic prey being flushed into the mainstem during heavy rain events.5.Our results illustrate that large tributaries can create seasonal discontinuities, influencing riverine food web structure in terms of allochthony, food web diversity, and food chain length.6.Synthesis and applications. Pulsed flows from unregulated tributaries following seasonal monsoon rains increase the importance of terrestrially-derived organic matter in large, regulated river food webs, increasing food chain length and trophic diversity downstream of tributary inputs. Protecting unregulated tributaries within hydropower cascades may be important if we are to mitigate food web structure alteration due to flow regulation by large dams. This is critical in the light of global hydropower development, especially in megadiverse, developing countries where dam placement (including completed and planned structures) is in tributaries.

  9. Benchmarking Successional Progress in a Quantitative Food Web

    Science.gov (United States)

    Boit, Alice; Gaedke, Ursula

    2014-01-01

    Central to ecology and ecosystem management, succession theory aims to mechanistically explain and predict the assembly and development of ecological communities. Yet processes at lower hierarchical levels, e.g. at the species and functional group level, are rarely mechanistically linked to the under-investigated system-level processes which drive changes in ecosystem properties and functioning and are comparable across ecosystems. As a model system for secondary succession, seasonal plankton succession during the growing season is readily observable and largely driven autogenically. We used a long-term dataset from large, deep Lake Constance comprising biomasses, auto- and heterotrophic production, food quality, functional diversity, and mass-balanced food webs of the energy and nutrient flows between functional guilds of plankton and partly fish. Extracting population- and system-level indices from this dataset, we tested current hypotheses about the directionality of successional progress which are rooted in ecosystem theory, the metabolic theory of ecology, quantitative food web theory, thermodynamics, and information theory. Our results indicate that successional progress in Lake Constance is quantifiable, passing through predictable stages. Mean body mass, functional diversity, predator-prey weight ratios, trophic positions, system residence times of carbon and nutrients, and the complexity of the energy flow patterns increased during succession. In contrast, both the mass-specific metabolic activity and the system export decreased, while the succession rate exhibited a bimodal pattern. The weighted connectance introduced here represents a suitable index for assessing the evenness and interconnectedness of energy flows during succession. Diverging from earlier predictions, ascendency and eco-exergy did not increase during succession. Linking aspects of functional diversity to metabolic theory and food web complexity, we reconcile previously disjoint bodies of

  10. Benchmarking successional progress in a quantitative food web.

    Directory of Open Access Journals (Sweden)

    Alice Boit

    Full Text Available Central to ecology and ecosystem management, succession theory aims to mechanistically explain and predict the assembly and development of ecological communities. Yet processes at lower hierarchical levels, e.g. at the species and functional group level, are rarely mechanistically linked to the under-investigated system-level processes which drive changes in ecosystem properties and functioning and are comparable across ecosystems. As a model system for secondary succession, seasonal plankton succession during the growing season is readily observable and largely driven autogenically. We used a long-term dataset from large, deep Lake Constance comprising biomasses, auto- and heterotrophic production, food quality, functional diversity, and mass-balanced food webs of the energy and nutrient flows between functional guilds of plankton and partly fish. Extracting population- and system-level indices from this dataset, we tested current hypotheses about the directionality of successional progress which are rooted in ecosystem theory, the metabolic theory of ecology, quantitative food web theory, thermodynamics, and information theory. Our results indicate that successional progress in Lake Constance is quantifiable, passing through predictable stages. Mean body mass, functional diversity, predator-prey weight ratios, trophic positions, system residence times of carbon and nutrients, and the complexity of the energy flow patterns increased during succession. In contrast, both the mass-specific metabolic activity and the system export decreased, while the succession rate exhibited a bimodal pattern. The weighted connectance introduced here represents a suitable index for assessing the evenness and interconnectedness of energy flows during succession. Diverging from earlier predictions, ascendency and eco-exergy did not increase during succession. Linking aspects of functional diversity to metabolic theory and food web complexity, we reconcile

  11. Benchmarking successional progress in a quantitative food web.

    Science.gov (United States)

    Boit, Alice; Gaedke, Ursula

    2014-01-01

    Central to ecology and ecosystem management, succession theory aims to mechanistically explain and predict the assembly and development of ecological communities. Yet processes at lower hierarchical levels, e.g. at the species and functional group level, are rarely mechanistically linked to the under-investigated system-level processes which drive changes in ecosystem properties and functioning and are comparable across ecosystems. As a model system for secondary succession, seasonal plankton succession during the growing season is readily observable and largely driven autogenically. We used a long-term dataset from large, deep Lake Constance comprising biomasses, auto- and heterotrophic production, food quality, functional diversity, and mass-balanced food webs of the energy and nutrient flows between functional guilds of plankton and partly fish. Extracting population- and system-level indices from this dataset, we tested current hypotheses about the directionality of successional progress which are rooted in ecosystem theory, the metabolic theory of ecology, quantitative food web theory, thermodynamics, and information theory. Our results indicate that successional progress in Lake Constance is quantifiable, passing through predictable stages. Mean body mass, functional diversity, predator-prey weight ratios, trophic positions, system residence times of carbon and nutrients, and the complexity of the energy flow patterns increased during succession. In contrast, both the mass-specific metabolic activity and the system export decreased, while the succession rate exhibited a bimodal pattern. The weighted connectance introduced here represents a suitable index for assessing the evenness and interconnectedness of energy flows during succession. Diverging from earlier predictions, ascendency and eco-exergy did not increase during succession. Linking aspects of functional diversity to metabolic theory and food web complexity, we reconcile previously disjoint bodies of

  12. Evidence for the persistence of food web structure after amphibian extirpation in a Neotropical stream.

    Science.gov (United States)

    Barnum, Thomas R; Drake, John M; Colón-Gaud, Checo; Rugenski, Amanda T; Frauendorf, Therese C; Connelly, Scott; Kilham, Susan S; Whiles, Matt R; Lips, Karen R; Pringle, Catherine M

    2015-08-01

    Species losses are predicted to simplify food web structure, and disease-driven amphibian declines in Central America offer an opportunity to test this prediction. Assessment of insect community composition, combined with gut content analyses, was used to generate periphyton-insect food webs for a Panamanian stream, both pre- and post-amphibian decline. We then used network analysis to assess the effects of amphibian declines on food web structure. Although 48% of consumer taxa, including many insect taxa, were lost between pre- and post-amphibian decline sampling dates, connectance declined by less than 3%. We then quantified the resilience of food web structure by calculating the number of expected cascading extirpations from the loss of tadpoles. This analysis showed the expected effects of species loss on connectance and linkage density to be more than 60% and 40%, respectively, than were actually observed. Instead, new trophic linkages in the post-decline food web reorganized the food web topology, changing the identity of "hub" taxa, and consequently reducing the effects of amphibian declines on many food web attributes. Resilience of food web attributes was driven by a combination of changes in consumer diets, particularly those of insect predators, as well as the appearance of generalist insect consumers, suggesting that food web structure is maintained by factors independent of the original trophic linkages.

  13. Soil fertility shapes belowground food webs across a regional climate gradient.

    Science.gov (United States)

    Laliberté, Etienne; Kardol, Paul; Didham, Raphael K; Teste, François P; Turner, Benjamin L; Wardle, David A

    2017-10-01

    Changes in soil fertility during pedogenesis affect the quantity and quality of resources entering the belowground subsystem. Climate governs pedogenesis, yet how climate modulates responses of soil food webs to soil ageing remains unexplored because of the paucity of appropriate model systems. We characterised soil food webs along each of four retrogressive soil chronosequences situated across a strong regional climate gradient to show that belowground communities are predominantly shaped by changes in fertility rather than climate. Basal consumers showed hump-shaped responses to soil ageing, which were propagated to higher-order consumers. There was a shift in dominance from bacterial to fungal energy channels with increasing soil age, while the root energy channel was most important in intermediate-aged soils. Our study highlights the overarching importance of soil fertility in regulating soil food webs, and indicates that belowground food webs will respond more strongly to shifts in soil resources than climate change. © 2017 John Wiley & Sons Ltd/CNRS.

  14. Planktonic food webs revisited: Reanalysis of results from the linear inverse approach

    Science.gov (United States)

    Hlaili, Asma Sakka; Niquil, Nathalie; Legendre, Louis

    2014-01-01

    Identification of the trophic pathway that dominates a given planktonic assemblage is generally based on the distribution of biomasses among food-web compartments, or better, the flows of materials or energy among compartments. These flows are obtained by field observations and a posteriori analyses, including the linear inverse approach. In the present study, we re-analysed carbon flows obtained by inverse analysis at 32 stations in the global ocean and one large lake. Our results do not support two "classical" views of plankton ecology, i.e. that the herbivorous food web is dominated by mesozooplankton grazing on large phytoplankton, and the microbial food web is based on microzooplankton significantly consuming bacteria; our results suggest instead that phytoplankton are generally grazed by microzooplankton, of which they are the main food source. Furthermore, we identified the "phyto-microbial food web", where microzooplankton largely feed on phytoplankton, in addition to the already known "poly-microbial food web", where microzooplankton consume more or less equally various types of food. These unexpected results led to a (re)definition of the conceptual models corresponding to the four trophic pathways we found to exist in plankton, i.e. the herbivorous, multivorous, and two types of microbial food web. We illustrated the conceptual trophic pathways using carbon flows that were actually observed at representative stations. The latter can be calibrated to correspond to any field situation. Our study also provides researchers and managers with operational criteria for identifying the dominant trophic pathway in a planktonic assemblage, these criteria being based on the values of two carbon ratios that could be calculated from flow values that are relatively easy to estimate in the field.

  15. Feasibility of 2 x 24-h dietary recalls combined with a food-recording booklet, using EPIC-Soft, among schoolchildren

    DEFF Research Database (Denmark)

    Trolle, Ellen; Amiano, P.; Ege, Majken

    2011-01-01

    Background/Objectives: The aim of this study was to evaluate the feasibility of the suggested trans-European methodology for undertaking representative dietary surveys among schoolchildren: 2 x 24-h dietary recalls (24-HDRs) combined with a food-recording booklet, using EPIC-Soft (the software......-8 years and 47 children aged 12-13 years were recruited through schools in Spain. Each child with one parent completed two face-to-face 24-HDRs, combined with optional use of a food-recording booklet (FRB) to be filled in by the child, a parent or other proxy persons for preparing the recalls. Feasibility...

  16. Assessing the intake of obesity-related foods and beverages in young children: comparison of a simple population survey with 24 hr-recall

    Directory of Open Access Journals (Sweden)

    Bell Andrew C

    2009-10-01

    Full Text Available Abstract Background With an increasing focus on obesity prevention there is a need for simple, valid tools to assess dietary indicators that may be the targets of intervention programs. The objective of this study was to determine the relative validity of previous day dietary intake using a newly developed parent-proxy questionnaire (EPAQ for two to five year old children. Methods A convenience sample of participants (n = 90 recruited through preschools and the community in Geelong, Australia provided dietary data for their child via EPAQ and interviewer-administered 24-hour dietary recall (24 hr-recall. Comparison of mean food and beverage group servings between the EPAQ and 24 hr-recall was conducted and Spearman rank correlations were computed to examine the association between the two methods. Results Mean servings of food/beverage groups were comparable between methods for all groups except water, and significant correlations were found between the servings of food and beverages using the EPAQ and 24-hr recall methods (ranging from 0.57 to 0.88. Conclusion The EPAQ is a simple and useful population-level tool for estimating the intake of obesity-related foods and beverages in children aged two to five years. When compared with 24-hour recall data, the EPAQ produced an acceptable level of relative validity and this short survey has application for population monitoring and the evaluation of population-based obesity prevention interventions for young children.

  17. Seasonal variation in mercury and food web biomagnification in Lake Ontario, Canada

    International Nuclear Information System (INIS)

    Zhang Liang; Campbell, Linda M.; Johnson, Timothy B.

    2012-01-01

    Seasonal variation in mercury (Hg) concentrations and food web structure was assessed for eastern Lake Ontario. Hg concentrations, measured in 6 species of invertebrates and 8 species of fishes, tended to be highest in the spring and lowest in the summer for most biota. Yellow perch (Perca flavescens) exhibited significant ontogenetic shifts in diet and Hg, although such patterns were not evident for other species. Food web structure, as indicated by stable isotope values (δ 15 N, δ 13 C) was not static. Log-transformed Hg data were strongly and consistently correlated with δ 15 N values for the whole food web in each of the three seasons (slopes, 0.17–0.24) and across the entire year (slope, 0.2). While significantly different between seasons, the regression slope values are still consistent with published global Hg biomagnification rates. Our results indicate that the assessment of Hg trends in Great Lakes must take into account seasonal patterns and time of sampling. - Graphical abstract: Total mercury concentrations and trophic level (δ 15 N) regressions for organisms from the littoral Lake Ontario food web of Waupoos in 2009. Filled circles represent invertebrates while open circles represent fish. Dashed lines represents the regression between δ 15 N and THg of “whole” food web (log-Hg-δ 15 N regression equations in the upper left hand corner in each plot), and solid lines represents the regression between δ 15 N and THg of “fish-only” food web (log-Hg-δ 15 N regression equations in the lower right hand corner of each plot). Note that the y-axis is untransformed Hg concentrations plotted along a logarithmic scale, while the equations are based on log-transformed Hg values. Highlights: ► Most fish in littoral Lake Ontario had higher Hg concentrations in spring and lower Hg in summer. ► Log Hg consistently biomagnified throughout the food web in each season and for the year. ► Biomagnification rates (e.g., log Hg-δ 15 N slopes) vary

  18. The meaning of functional trait composition of food webs for ecosystem functioning.

    Science.gov (United States)

    Gravel, Dominique; Albouy, Camille; Thuiller, Wilfried

    2016-05-19

    There is a growing interest in using trait-based approaches to characterize the functional structure of animal communities. Quantitative methods have been derived mostly for plant ecology, but it is now common to characterize the functional composition of various systems such as soils, coral reefs, pelagic food webs or terrestrial vertebrate communities. With the ever-increasing availability of distribution and trait data, a quantitative method to represent the different roles of animals in a community promise to find generalities that will facilitate cross-system comparisons. There is, however, currently no theory relating the functional composition of food webs to their dynamics and properties. The intuitive interpretation that more functional diversity leads to higher resource exploitation and better ecosystem functioning was brought from plant ecology and does not apply readily to food webs. Here we appraise whether there are interpretable metrics to describe the functional composition of food webs that could foster a better understanding of their structure and functioning. We first distinguish the various roles that traits have on food web topology, resource extraction (bottom-up effects), trophic regulation (top-down effects), and the ability to keep energy and materials within the community. We then discuss positive effects of functional trait diversity on food webs, such as niche construction and bottom-up effects. We follow with a discussion on the negative effects of functional diversity, such as enhanced competition (both exploitation and apparent) and top-down control. Our review reveals that most of our current understanding of the impact of functional trait diversity on food web properties and functioning comes from an over-simplistic representation of network structure with well-defined levels. We, therefore, conclude with propositions for new research avenues for both theoreticians and empiricists. © 2016 The Author(s).

  19. Designing Industrial Networks Using Ecological Food Web Metrics.

    Science.gov (United States)

    Layton, Astrid; Bras, Bert; Weissburg, Marc

    2016-10-18

    Biologically Inspired Design (biomimicry) and Industrial Ecology both look to natural systems to enhance the sustainability and performance of engineered products, systems and industries. Bioinspired design (BID) traditionally has focused on a unit operation and single product level. In contrast, this paper describes how principles of network organization derived from analysis of ecosystem properties can be applied to industrial system networks. Specifically, this paper examines the applicability of particular food web matrix properties as design rules for economically and biologically sustainable industrial networks, using an optimization model developed for a carpet recycling network. Carpet recycling network designs based on traditional cost and emissions based optimization are compared to designs obtained using optimizations based solely on ecological food web metrics. The analysis suggests that networks optimized using food web metrics also were superior from a traditional cost and emissions perspective; correlations between optimization using ecological metrics and traditional optimization ranged generally from 0.70 to 0.96, with flow-based metrics being superior to structural parameters. Four structural food parameters provided correlations nearly the same as that obtained using all structural parameters, but individual structural parameters provided much less satisfactory correlations. The analysis indicates that bioinspired design principles from ecosystems can lead to both environmentally and economically sustainable industrial resource networks, and represent guidelines for designing sustainable industry networks.

  20. Ecological-network models link diversity, structure and function in the plankton food-web

    Science.gov (United States)

    D'Alelio, Domenico; Libralato, Simone; Wyatt, Timothy; Ribera D'Alcalà, Maurizio

    2016-02-01

    A planktonic food-web model including sixty-three functional nodes (representing auto- mixo- and heterotrophs) was developed to integrate most trophic diversity present in the plankton. The model was implemented in two variants - which we named ‘green’ and ‘blue’ - characterized by opposite amounts of phytoplankton biomass and representing, respectively, bloom and non-bloom states of the system. Taxonomically disaggregated food-webs described herein allowed to shed light on how components of the plankton community changed their trophic behavior in the two different conditions, and modified the overall functioning of the plankton food web. The green and blue food-webs showed distinct organizations in terms of trophic roles of the nodes and carbon fluxes between them. Such re-organization stemmed from switches in selective grazing by both metazoan and protozoan consumers. Switches in food-web structure resulted in relatively small differences in the efficiency of material transfer towards higher trophic levels. For instance, from green to blue states, a seven-fold decrease in phytoplankton biomass translated into only a two-fold decrease in potential planktivorous fish biomass. By linking diversity, structure and function in the plankton food-web, we discuss the role of internal mechanisms, relying on species-specific functionalities, in driving the ‘adaptive’ responses of plankton communities to perturbations.

  1. Parasites affect food web structure primarily through increased diversity and complexity.

    Directory of Open Access Journals (Sweden)

    Jennifer A Dunne

    Full Text Available Comparative research on food web structure has revealed generalities in trophic organization, produced simple models, and allowed assessment of robustness to species loss. These studies have mostly focused on free-living species. Recent research has suggested that inclusion of parasites alters structure. We assess whether such changes in network structure result from unique roles and traits of parasites or from changes to diversity and complexity. We analyzed seven highly resolved food webs that include metazoan parasite data. Our analyses show that adding parasites usually increases link density and connectance (simple measures of complexity, particularly when including concomitant links (links from predators to parasites of their prey. However, we clarify prior claims that parasites "dominate" food web links. Although parasites can be involved in a majority of links, in most cases classic predation links outnumber classic parasitism links. Regarding network structure, observed changes in degree distributions, 14 commonly studied metrics, and link probabilities are consistent with scale-dependent changes in structure associated with changes in diversity and complexity. Parasite and free-living species thus have similar effects on these aspects of structure. However, two changes point to unique roles of parasites. First, adding parasites and concomitant links strongly alters the frequency of most motifs of interactions among three taxa, reflecting parasites' roles as resources for predators of their hosts, driven by trophic intimacy with their hosts. Second, compared to free-living consumers, many parasites' feeding niches appear broader and less contiguous, which may reflect complex life cycles and small body sizes. This study provides new insights about generic versus unique impacts of parasites on food web structure, extends the generality of food web theory, gives a more rigorous framework for assessing the impact of any species on trophic

  2. More than a meal: integrating non-feeding interactions into food webs

    Science.gov (United States)

    Kéfi, Sonia; Berlow, Eric L.; Wieters, Evie A.; Navarrete, Sergio A.; Petchey, Owen L.; Wood, Spencer A.; Boit, Alice; Joppa, Lucas N.; Lafferty, Kevin D.; Williams, Richard J.; Martinez, Neo D.; Menge, Bruce A.; Blanchette, Carol A.; Iles, Alison C.; Brose, Ulrich

    2012-01-01

    Organisms eating each other are only one of many types of well documented and important interactions among species. Other such types include habitat modification, predator interference and facilitation. However, ecological network research has been typically limited to either pure food webs or to networks of only a few (conceptual framework that organises this diversity into three main functional classes defined by how they modify specific parameters in a dynamic food web model. This approach provides a path forward for incorporating non-trophic interactions in traditional food web models and offers a new perspective on tackling ecological complexity that should stimulate both theoretical and empirical approaches to understanding the patterns and dynamics of diverse species interactions in nature.

  3. Boosted food web productivity through ocean acidification collapses under warming.

    Science.gov (United States)

    Goldenberg, Silvan U; Nagelkerken, Ivan; Ferreira, Camilo M; Ullah, Hadayet; Connell, Sean D

    2017-10-01

    Future climate is forecast to drive bottom-up (resource driven) and top-down (consumer driven) change to food web dynamics and community structure. Yet, our predictive understanding of these changes is hampered by an over-reliance on simplified laboratory systems centred on single trophic levels. Using a large mesocosm experiment, we reveal how future ocean acidification and warming modify trophic linkages across a three-level food web: that is, primary (algae), secondary (herbivorous invertebrates) and tertiary (predatory fish) producers. Both elevated CO 2 and elevated temperature boosted primary production. Under elevated CO 2 , the enhanced bottom-up forcing propagated through all trophic levels. Elevated temperature, however, negated the benefits of elevated CO 2 by stalling secondary production. This imbalance caused secondary producer populations to decline as elevated temperature drove predators to consume their prey more rapidly in the face of higher metabolic demand. Our findings demonstrate how anthropogenic CO 2 can function as a resource that boosts productivity throughout food webs, and how warming can reverse this effect by acting as a stressor to trophic interactions. Understanding the shifting balance between the propagation of resource enrichment and its consumption across trophic levels provides a predictive understanding of future dynamics of stability and collapse in food webs and fisheries production. © 2017 John Wiley & Sons Ltd.

  4. Incorporation of an invasive plant into a native insect herbivore food web

    NARCIS (Netherlands)

    Schilthuizen, Menno; Santos Pimenta, Lúcia P; Lammers, Youri; Steenbergen, Peter J; Flohil, Marco; Beveridge, Nils G P; van Duijn, Pieter T; Meulblok, Marjolein M; Sosef, Nils; van de Ven, Robin; Werring, Ralf; Beentjes, Kevin K; Meijer, Kim; Vos, Rutger A; Vrieling, Klaas; Gravendeel, Barbara; Choi, Young; Verpoorte, Robert; Smit, Chris; Beukeboom, Leo W

    2016-01-01

    The integration of invasive species into native food webs represent multifarious dynamics of ecological and evolutionary processes. We document incorporation of Prunus serotina (black cherry) into native insect food webs. We find that P. serotina harbours a herbivore community less dense but more

  5. Global change in the trophic functioning of marine food webs

    DEFF Research Database (Denmark)

    Maureaud, Aurore; Gascuel, Didier; Colléter, Mathieu

    2017-01-01

    and life history traits of marine species, we tested the hypothesis that anthropogenic ecological impacts may have led to changes in the global parameters defining the transfers of biomass within the food web. First, we developed two indicators to assess such changes: the Time Cumulated Indicator (TCI......The development of fisheries in the oceans, and other human drivers such as climate warming, have led to changes in species abundance, assemblages, trophic interactions, and ultimately in the functioning of marine food webs. Here, using a trophodynamic approach and global databases of catches......) measuring the residence time of biomass within the food web, and the Efficiency Cumulated Indicator (ECI) quantifying the fraction of secondary production reaching the top of the trophic chain. Then, we assessed, at the large marine ecosystem scale, the worldwide change of these two indicators over the 1950...

  6. Characteristics of Food Industry Web Sites and "Advergames" Targeting Children

    Science.gov (United States)

    Culp, Jennifer; Bell, Robert A.; Cassady, Diana

    2010-01-01

    Objective: To assess the content of food industry Web sites targeting children by describing strategies used to prolong their visits and foster brand loyalty; and to document health-promoting messages on these Web sites. Design: A content analysis was conducted of Web sites advertised on 2 children's networks, Cartoon Network and Nickelodeon. A…

  7. Ecological significance of hazardous concentrations in a planktonic food web

    OpenAIRE

    De Laender, F.; Soetaert, K.; De Schamphelaere, K.A.C.; Middelburg, J.J.; Janssen, C.R.

    2010-01-01

    Species sensitivity distributions (SSDs) are statistical distributions that are used to estimate the potentially affected fraction (PAF) of species at a given toxicant concentration, the hazardous concentration for that fraction of species (HCPAF). Here, we use an aquatic food web model that includes 14 phytoplankton and 6 zooplankton species to estimate the number of species experiencing a biomass reduction when the food web is exposed to the HCPAF and this for 1000 hypothetical toxicants an...

  8. Drug recall: An incubus for pharmaceutical companies and most serious drug recall of history.

    Science.gov (United States)

    Nagaich, Upendra; Sadhna, Divya

    2015-01-01

    There has been an increasing trend in the number of prescribed and over-the-counter drug recall over the last few years. The recall is usually due to company's discovery, customer's complaint or Food and Drug Administration (FDA) observation. The process of recall involves a planned specific course of action, which addresses the depth of recall, need for public warning, and the extent of effectiveness checks for the recall. The FDA review and/or recommend changes to the firm's recall strategy, as appropriate. The critical recall information list includes the identity of the product; summary of the failure; amount of product produced in the distribution chain and direct account. Product recalls clashes thousands of companies every year affecting: sales, testing customer relationships and disrupting supply chains. Drug recall is incubus for pharmaceutical companies. It effects the reputation of the company. The reason for the recall can be divided into two categories: manufacturing affined and safety/efficacy affined. It is essential to follow all the guidelines related to drug development and manufacturing procedure so as to minimize drug recall.

  9. Food web topology and parasites in the pelagic zone of a subarctic lake

    Science.gov (United States)

    Amundsen, Per-Arne; Lafferty, K.D.; Knudsen, R.; Primicerio, R.; Klemetsen, A.; Kuris, A.M.

    2009-01-01

    Parasites permeate trophic webs with their often complex life cycles, but few studies have included parasitism in food web analyses. Here we provide a highly resolved food web from the pelagic zone of a subarctic lake and explore how the incorporation of parasites alters the topology of the web. 2. Parasites used hosts at all trophic levels and increased both food-chain lengths and the total number of trophic levels. Their inclusion in the network analyses more than doubled the number of links and resulted in an increase in important food-web characteristics such as linkage density and connectance. 3. More than half of the parasite taxa were trophically transmitted, exploiting hosts at multiple trophic levels and thus increasing the degree of omnivory in the trophic web. 4. For trophically transmitted parasites, the number of parasite-host links exhibited a positive correlation with the linkage density of the host species, whereas no such relationship was seen for nontrophically transmitted parasites. Our findings suggest that the linkage density of free-living species affects their exposure to trophically transmitted parasites, which may be more likely to adopt highly connected species as hosts during the evolution of complex life cycles. 5. The study supports a prominent role for parasites in ecological networks and demonstrates that their incorporation may substantially alter considerations of food-web structure and functioning. ?? 2009 British Ecological Society.

  10. Benthic primary producers are key to sustain the Wadden Sea food web

    NARCIS (Netherlands)

    Christianen, M.J.A.; Middelburg, J.J.; Holthuijsen, S.J.; Jouta, J.; Compton, T.J.; Heide, van der T.; Piersma, T.; Sinninghe Damsté, J.S.; Veer, van der H.W.; Schouten, S.; Olff, H.

    2017-01-01

    Coastal food webs can be supported by local benthic or pelagic primary producers and by the import of organic matter. Distinguishing between these energy sources is essential for our understanding of ecosystem functioning. However, the relative contribution of these components to the food web at the

  11. Stable isotopes dissect aquatic food webs from the top to the bottom

    NARCIS (Netherlands)

    Middelburg, J.J.

    2014-01-01

    Stable isotopes have been used extensively to study food-web functioning, that is, the flow of energy and matter among organisms. Traditional food-web studies are based on the natural variability of isotopes and are limited to larger organisms that can be physically separated from their environment.

  12. Anthropogenic and natural sources of acidity and metals and their influence on the structure of stream food webs

    International Nuclear Information System (INIS)

    Hogsden, Kristy L.; Harding, Jon S.

    2012-01-01

    We compared food web structure in 20 streams with either anthropogenic or natural sources of acidity and metals or circumneutral water chemistry in New Zealand. Community and diet analysis indicated that mining streams receiving anthropogenic inputs of acidic and metal-rich drainage had much simpler food webs (fewer species, shorter food chains, less links) than those in naturally acidic, naturally high metal, and circumneutral streams. Food webs of naturally high metal streams were structurally similar to those in mining streams, lacking fish predators and having few species. Whereas, webs in naturally acidic streams differed very little from those in circumneutral streams due to strong similarities in community composition and diets of secondary and top consumers. The combined negative effects of acidity and metals on stream food webs are clear. However, elevated metal concentrations, regardless of source, appear to play a more important role than acidity in driving food web structure. - Highlights: ► Food webs in acid mine drainage impacted streams are small and extremely simplified. ► Conductivity explained differences in food web properties between streams. ► Number of links and web size accounted for much dissimilarity between food webs. ► Food web structure was comparable in naturally acidic and circumneutral streams. - Food web structure differs in streams with anthropogenic and natural sources of acidity and metals.

  13. Feeding environment and other traits shape species' roles in marine food webs.

    Science.gov (United States)

    Cirtwill, Alyssa R; Eklöf, Anna

    2018-04-02

    Food webs and meso-scale motifs allow us to understand the structure of ecological communities and define species' roles within them. This species-level perspective on networks permits tests for relationships between species' traits and their patterns of direct and indirect interactions. Such relationships could allow us to predict food-web structure based on more easily obtained trait information. Here, we calculated the roles of species (as vectors of motif position frequencies) in six well-resolved marine food webs and identified the motif positions associated with the greatest variation in species' roles. We then tested whether the frequencies of these positions varied with species' traits. Despite the coarse-grained traits we used, our approach identified several strong associations between traits and motifs. Feeding environment was a key trait in our models and may shape species' roles by affecting encounter probabilities. Incorporating environment into future food-web models may improve predictions of an unknown network structure. © 2018 John Wiley & Sons Ltd/CNRS.

  14. Validation of an Online Food Frequency Questionnaire against Doubly Labelled Water and 24 h Dietary Recalls in Pre-School Children

    Directory of Open Access Journals (Sweden)

    Christine Delisle Nyström

    2017-01-01

    Full Text Available The development of easy-to-use and accurate methods to assess the intake of energy, foods and nutrients in pre-school children is needed. KidMeal-Q is an online food frequency questionnaire developed for the LifeGene prospective cohort study in Sweden. The aims of this study were to compare: (i energy intake (EI obtained using KidMeal-Q to total energy expenditure (TEE measured via doubly labelled water and (ii the intake of certain foods measured using KidMeal-Q to intakes acquired by means of 24 h dietary recalls in 38 children aged 5.5 years. The mean EI calculated using KidMeal-Q was statistically different (p < 0.001 from TEE (4670 ± 1430 kJ/24 h and 6070 ± 690 kJ/24 h, respectively. Significant correlations were observed for vegetables, fruit juice and candy between KidMeal-Q and 24 h dietary recalls. Only sweetened beverage consumption was significantly different in mean intake (p < 0.001, as measured by KidMeal-Q and 24 h dietary recalls. In conclusion, KidMeal-Q had a relatively short answering time and comparative validity to other food frequency questionnaires. However, its accuracy needs to be improved before it can be used in studies in pre-school children.

  15. Species richness and trophic diversity increase decomposition in a co-evolved food web.

    Directory of Open Access Journals (Sweden)

    Benjamin Baiser

    Full Text Available Ecological communities show great variation in species richness, composition and food web structure across similar and diverse ecosystems. Knowledge of how this biodiversity relates to ecosystem functioning is important for understanding the maintenance of diversity and the potential effects of species losses and gains on ecosystems. While research often focuses on how variation in species richness influences ecosystem processes, assessing species richness in a food web context can provide further insight into the relationship between diversity and ecosystem functioning and elucidate potential mechanisms underpinning this relationship. Here, we assessed how species richness and trophic diversity affect decomposition rates in a complete aquatic food web: the five trophic level web that occurs within water-filled leaves of the northern pitcher plant, Sarracenia purpurea. We identified a trophic cascade in which top-predators--larvae of the pitcher-plant mosquito--indirectly increased bacterial decomposition by preying on bactivorous protozoa. Our data also revealed a facultative relationship in which larvae of the pitcher-plant midge increased bacterial decomposition by shredding detritus. These important interactions occur only in food webs with high trophic diversity, which in turn only occur in food webs with high species richness. We show that species richness and trophic diversity underlie strong linkages between food web structure and dynamics that influence ecosystem functioning. The importance of trophic diversity and species interactions in determining how biodiversity relates to ecosystem functioning suggests that simply focusing on species richness does not give a complete picture as to how ecosystems may change with the loss or gain of species.

  16. 21 CFR 7.46 - Firm-initiated recall.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Firm-initiated recall. 7.46 Section 7.46 Food and....46 Firm-initiated recall. (a) A firm may decide of its own volition and under any circumstances to remove or correct a distributed product. A firm that does so because it believes the product to be...

  17. Evaluation of 2 × 24-h dietary recalls combined with a food-recording booklet, against a 7-day food-record method among schoolchildren

    DEFF Research Database (Denmark)

    Trolle, Ellen; Amiano, P.; Ege, Majken

    2011-01-01

    Background/Objectives:The aim of this study was to evaluate the estimated energy, nutrient and food intake from the suggested trans-European methodology for undertaking representative dietary surveys among schoolchildren: 2 Ã 24-h dietary recalls (24-HDRs) combined with a food-recording booklet...... (FRB), using EPIC-Soft pc-program (the software developed to conduct 24-HDRs in the European Prospective Investigation into Cancer and Nutrition (EPIC) Study), against a 7-day food-record (7-dFR) method among Danish schoolchildren.Subjects/Methods:A total of 74 children aged 7-8 years and 70 children...

  18. Comparison of the Block Kid's Food Frequency Questionnaire with a 24 h dietary recall methodology among Hmong-American children, 9-18 years of age.

    Science.gov (United States)

    Mulasi-Pokhriyal, Urvashi; Smith, Chery

    2013-01-28

    Hmong are one of the immigrant Asian subgroups with increasing rates of obesity, type 2 diabetes and CVD. Despite their population growth in the USA and declining health status, no research has investigated the appropriateness of dietary assessment measures, including FFQ and 24 h dietary recalls among Hmong. The present study compared the nutrient information obtained through a 24 h dietary recall method with that collected using the Block Kid's Food Frequency Questionnaire (Block FFQ) among Hmong-American children (n 335) of 9-18 years of age. For this purpose, two 24 h dietary recalls were collected during non-consecutive days and averaged for comparison. The Block FFQ was administered on the day of the second 24 h recall and the two methodologies were also compared using t tests. Among all children, Block FFQ nutrient estimates for vitamin A, vitamin C and food group servings for vegetables and fruits were significantly higher than those assessed through the 24 h dietary recalls (Pfood group servings for grains and meat and beans were significantly higher among all participants when assessed through the 24 h dietary recalls than through the Block FFQ (Pfood options otherwise missed in the Block FFQ. We recommend the modification of the current Block FFQ to appropriately reflect cultural food/beverage items of the population in interest.

  19. Developing a broader scientific foundation for river restoration: Columbia River food webs

    Science.gov (United States)

    Robert J. Naiman; J. Richard Alldredge; David A. Beauchamp; Peter A. Bisson; James Congleton; Charles J. Henny; Nancy Huntly; Roland Lamberson; Colin Levings; Erik N. Merrill; William G. Pearcy; Bruce E. Rieman; Gregory T. Ruggerone; Dennis Scarnecchia; Peter E. Smouse; Chris C. Wood

    2012-01-01

    Well-functioning food webs are fundamental for sustaining rivers as ecosystems and maintaining associated aquatic and terrestrial communities. The current emphasis on restoring habitat structure-without explicitly considering food webs-has been less successful than hoped in terms of enhancing the status of targeted species and often overlooks important constraints on...

  20. Children's implicit recall of junk food, alcohol and gambling sponsorship in Australian sport.

    Science.gov (United States)

    Bestman, Amy; Thomas, Samantha L; Randle, Melanie; Thomas, Stuart D M

    2015-10-05

    In Australia, sport is saturated by the promotion of junk food, alcohol and gambling products. This is particularly evident on player jerseys. The effect of this advertising on children, who are exposed to these messages while watching sport, has not been thoroughly investigated. The aim of this research study was to investigate: (1) the extent to which children implicitly recalled shirt sponsors with the correct sporting team; (2) whether children associated some types of sponsors with certain sporting codes more than others; and (3) whether age of the children influenced the correct recall of sponsoring brands and teams. This experimental study conducted in New South Wales, Australia used projective techniques to measure the implicit recall of team sponsorship relationships of 85 children aged 5-12 years. Participants were asked to arrange two sets of magnets - one which contained sporting teams and one which contained brand logos - in the manner deemed most appropriate by them. Children were not given any prompts relating to sporting sponsorship relationships. Three quarters (77 %) of the children were able to identify at least one correct shirt sponsor. Children associated alcohol and gambling brands more highly with the more popular sporting code, the National Rugby League compared to the Australian Football League sporting code. Results showed that age had an effect on number of shirt sponsors correctly recalled with 9-12 year olds being significantly more likely than 5-8 year olds to correctly identify team sponsors. Given children's ability to implicitly recall shirt sponsors in a sporting context, Australian sporting codes should examine their current sponsorship relationships to reduce the number of unhealthy commodity shirt sponsors. While there is some regulation that protects children from the marketing of unhealthy commodity products, these findings suggest that children are still exposed to and recall these sponsorship relationships. Results suggest

  1. Disentangling the root- and detritus-based food chain in the micro-food web of an arable soil by plant removal.

    Directory of Open Access Journals (Sweden)

    Olena Glavatska

    Full Text Available Soil food web structure and function is primarily determined by the major basal resources, which are living plant tissue, root exudates and dead organic matter. A field experiment was performed to disentangle the interlinkage of the root-and detritus-based soil food chains. An arable site was cropped either with maize, amended with maize shoot litter or remained bare soil, representing food webs depending on roots, aboveground litter and soil organic matter as predominant resource, respectively. The soil micro-food web, i.e. microorganisms and nematodes, was investigated in two successive years along a depth transect. The community composition of nematodes was used as model to determine the changes in the rhizosphere, detritusphere and bulk soil food web. In the first growing season the impact of treatments on the soil micro-food web was minor. In the second year plant-feeding nematodes increased under maize, whereas after harvest the Channel Index assigned promotion of the detritivore food chain, reflecting decomposition of root residues. The amendment with litter did not foster microorganisms, instead biomass of Gram-positive and Gram-negative bacteria as well as that of fungi declined in the rooted zone. Likely higher grazing pressure by nematodes reduced microbial standing crop as bacterial and fungal feeders increased. However, populations at higher trophic levels were not promoted, indicating limited flux of litter resources along the food chain. After two years of bare soil microbial biomass and nematode density remained stable, pointing to soil organic matter-based resources that allow bridging periods with deprivation. Nematode communities were dominated by opportunistic taxa that are competitive at moderate resource supply. In sum, removal of plants from the system had less severe effects than expected, suggesting considerable food web resilience to the disruption of both the root and detrital carbon channel, pointing to a legacy of

  2. Disentangling the root- and detritus-based food chain in the micro-food web of an arable soil by plant removal.

    Science.gov (United States)

    Glavatska, Olena; Müller, Karolin; Butenschoen, Olaf; Schmalwasser, Andreas; Kandeler, Ellen; Scheu, Stefan; Totsche, Kai Uwe; Ruess, Liliane

    2017-01-01

    Soil food web structure and function is primarily determined by the major basal resources, which are living plant tissue, root exudates and dead organic matter. A field experiment was performed to disentangle the interlinkage of the root-and detritus-based soil food chains. An arable site was cropped either with maize, amended with maize shoot litter or remained bare soil, representing food webs depending on roots, aboveground litter and soil organic matter as predominant resource, respectively. The soil micro-food web, i.e. microorganisms and nematodes, was investigated in two successive years along a depth transect. The community composition of nematodes was used as model to determine the changes in the rhizosphere, detritusphere and bulk soil food web. In the first growing season the impact of treatments on the soil micro-food web was minor. In the second year plant-feeding nematodes increased under maize, whereas after harvest the Channel Index assigned promotion of the detritivore food chain, reflecting decomposition of root residues. The amendment with litter did not foster microorganisms, instead biomass of Gram-positive and Gram-negative bacteria as well as that of fungi declined in the rooted zone. Likely higher grazing pressure by nematodes reduced microbial standing crop as bacterial and fungal feeders increased. However, populations at higher trophic levels were not promoted, indicating limited flux of litter resources along the food chain. After two years of bare soil microbial biomass and nematode density remained stable, pointing to soil organic matter-based resources that allow bridging periods with deprivation. Nematode communities were dominated by opportunistic taxa that are competitive at moderate resource supply. In sum, removal of plants from the system had less severe effects than expected, suggesting considerable food web resilience to the disruption of both the root and detrital carbon channel, pointing to a legacy of organic matter

  3. Web-Based Virtual Laboratory for Food Analysis Course

    Science.gov (United States)

    Handayani, M. N.; Khoerunnisa, I.; Sugiarti, Y.

    2018-02-01

    Implementation of learning on food analysis course in Program Study of Agro-industrial Technology Education faced problems. These problems include the availability of space and tools in the laboratory that is not comparable with the number of students also lack of interactive learning tools. On the other hand, the information technology literacy of students is quite high as well the internet network is quite easily accessible on campus. This is a challenge as well as opportunities in the development of learning media that can help optimize learning in the laboratory. This study aims to develop web-based virtual laboratory as one of the alternative learning media in food analysis course. This research is R & D (research and development) which refers to Borg & Gall model. The results showed that assessment’s expert of web-based virtual labs developed, in terms of software engineering aspects; visual communication; material relevance; usefulness and language used, is feasible as learning media. The results of the scaled test and wide-scale test show that students strongly agree with the development of web based virtual laboratory. The response of student to this virtual laboratory was positive. Suggestions from students provided further opportunities for improvement web based virtual laboratory and should be considered for further research.

  4. Microbial Food-Web Drivers in Tropical Reservoirs.

    Science.gov (United States)

    Domingues, Carolina Davila; da Silva, Lucia Helena Sampaio; Rangel, Luciana Machado; de Magalhães, Leonardo; de Melo Rocha, Adriana; Lobão, Lúcia Meirelles; Paiva, Rafael; Roland, Fábio; Sarmento, Hugo

    2017-04-01

    Element cycling in aquatic systems is driven chiefly by planktonic processes, and the structure of the planktonic food web determines the efficiency of carbon transfer through trophic levels. However, few studies have comprehensively evaluated all planktonic food-web components in tropical regions. The aim of this study was to unravel the top-down controls (metazooplankton community structure), bottom-up controls (resource availability), and hydrologic (water residence time) and physical (temperature) variables that affect different components of the microbial food web (MFW) carbon stock in tropical reservoirs, through structural equation models (SEM). We conducted a field study in four deep Brazilian reservoirs (Balbina, Tucuruí, Três Marias, and Funil) with different trophic states (oligo-, meso-, and eutrophic). We found evidence of a high contribution of the MFW (up to 50% of total planktonic carbon), especially in the less-eutrophic reservoirs (Balbina and Tucuruí). Bottom-up and top-down effects assessed through SEM indicated negative interactions between soluble reactive phosphorus and phototrophic picoplankton (PPP), dissolved inorganic nitrogen, and heterotrophic nanoflagellates (HNF). Copepods positively affected ciliates, and cladocerans positively affected heterotrophic bacteria (HB) and PPP. Higher copepod/cladoceran ratios and an indirect positive effect of copepods on HB might strengthen HB-HNF coupling. We also found low values for the degree of uncoupling (D) and a low HNF/HB ratio compared with literature data (mostly from temperate regions). This study demonstrates the importance of evaluating the whole size spectrum (including microbial compartments) of the different planktonic compartments, in order to capture the complex carbon dynamics of tropical aquatic ecosystems.

  5. What lies beneath? : Linking litter and canopy food webs to protect ornamental crops

    NARCIS (Netherlands)

    Muñoz Cárdenas, K.A.

    2017-01-01

    The main research question of this thesis was how interactions between above-ground and below-ground food webs affect biological control. Arthropod food webs associated with plants are commonly composed of several species of herbivores, the detritivore community, specialist and generalist predators

  6. Successional dynamics in the seasonally forced diamond food web.

    Science.gov (United States)

    Klausmeier, Christopher A; Litchman, Elena

    2012-07-01

    Plankton seasonal succession is a classic example of nonequilibrium community dynamics. Despite the fact that it has been well studied empirically, it lacks a general quantitative theory. Here we investigate a food web model that includes a resource, two phytoplankton, and a shared grazer-the diamond food web-in a seasonal environment. The model produces a number of successional trajectories that have been widely discussed in the context of the verbal Plankton Ecology Group model of succession, such as a spring bloom of a good competitor followed by a grazer-induced clear-water phase, setting the stage for the late-season dominance of a grazer-resistant species. It also predicts a novel, counterintuitive trajectory where the grazer-resistant species has both early- and late-season blooms. The model often generates regular annual cycles but sometimes produces multiyear cycles or chaos, even with identical forcing each year. Parameterizing the model, we show how the successional trajectory depends on nutrient supply and the length of the growing season, two key parameters that vary among water bodies. This model extends nonequilibrium theory to food webs and is a first step toward a quantitative theory of plankton seasonal succession.

  7. Anthropogenic shift of planktonic food web structure in a coastal lagoon by freshwater flow regulation

    Science.gov (United States)

    Hemraj, Deevesh A.; Hossain, A.; Ye, Qifeng; Qin, Jian G.; Leterme, Sophie C.

    2017-03-01

    Anthropogenic modification of aquatic systems has diverse impacts on food web interactions and ecosystem states. To reverse the adverse effects of modified freshwater flow, adequate management of discharge is required, especially due to higher water requirements and abstractions for human use. Here, we look at the effects of anthropogenically controlled freshwater flow regimes on the planktonic food web of a Ramsar listed coastal lagoon that is under recovery from degradation. Our results show shifts in water quality and plankton community interactions associated to changes in water flow. These shifts in food web interactions represent modifications in habitat complexity and water quality. At high flow, phytoplankton-zooplankton interactions dominate the food web. Conversely, at low flow, bacteria, viruses and nano/picoplankton interactions are more dominant, with a substantial switch of the food web towards heterotrophy. This switch can be associated with excess organic matter loading, decomposition of dead organisms, and synergistic and antagonistic interactions. We suggest that a lower variability in flow amplitude could be beneficial for the long-term sustaining of water quality and food web interactions, while improving the ecosystem health of systems facing similar stresses as the Coorong.

  8. Food Chains & Webs. A Multimedia CD-ROM. [CD-ROM].

    Science.gov (United States)

    2001

    This CD-ROM is designed for classroom and individual use to teach and learn about food chains and food webs. Integrated animations, custom graphics, three-dimensional representations, photographs, and sound are featured for use in user-controlled activities. Interactive lessons are available to reinforce the subject material. Pre- and post-testing…

  9. Unraveling the intricate dynamics of planktonic Arctic marine food webs. A sensitivity analysis of a well-documented food web model

    Science.gov (United States)

    Saint-Béat, Blanche; Maps, Frédéric; Babin, Marcel

    2018-01-01

    The extreme and variable environment shapes the functioning of Arctic ecosystems and the life cycles of its species. This delicate balance is now threatened by the unprecedented pace and magnitude of global climate change and anthropogenic pressure. Understanding the long-term consequences of these changes remains an elusive, yet pressing, goal. Our work was specifically aimed at identifying which biological processes impact Arctic planktonic ecosystem functioning, and how. Ecological Network Analysis (ENA) indices reveal emergent ecosystem properties that are not accessible through simple in situ observation. These indices are based on the architecture of carbon flows within food webs. But, despite the recent increase in in situ measurements from Arctic seas, many flow values remain unknown. Linear inverse modeling (LIM) allows missing flow values to be estimated from existing flow observations and, subsequent reconstruction of ecosystem food webs. Through a sensitivity analysis on a LIM model of the Amundsen Gulf in the Canadian Arctic, we were able to determine which processes affected the emergent properties of the planktonic ecosystem. The analysis highlighted the importance of an accurate knowledge of the various processes controlling bacterial production (e.g. bacterial growth efficiency and viral lysis). More importantly, a change in the fate of the microzooplankton within the food web can be monitored through the trophic level of mesozooplankton. It can be used as a "canary in the coal mine" signal, a forewarner of larger ecosystem change.

  10. Food web accumulation of cyclic siloxanes in Lake Mjøsa, Norway.

    Science.gov (United States)

    Borgå, Katrine; Fjeld, Eirik; Kierkegaard, Amelie; McLachlan, Michael S

    2012-06-05

    The biomagnification of the cyclic volatile methyl siloxanes octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexatetrasiloxane (D6) was analyzed in the Lake Mjøsa food web in Norway from zooplankton and Mysis to planktivorous and piscivorous fish. The trophic magnification factor (TMF) for D5 was determined and compared with TMFs of several legacy contaminants: polychlorinated biphenyl (PCB) congeners 153 and 180, polybrominated diphenyl ether (PBDE) congeners 47 and 99, and p,p'-DDE. D5 showed TMF significantly greater than 1, implying food web biomagnification (TMF = 2.28, CI: 1.22-4.29). This contrasts with two studies that reported TMF < 1, which may reflect variability in TMF between food webs. The Lake Mjøsa D5 TMF was sensitive to the species included at the higher trophic level; whole food web TMF differed from TMF excluding smelt (Osmerus eperlanus) or brown trout (Salmo trutta) (TMF(-SMELT) = 1.62, CI: 0.96-2.72; TMF(-TROUT) = 3.58, CI: 1.82-7.03). For legacy contaminants (e.g., PCB-153 and PCB-180), the TMFs were less sensitive to the food web composition, and a better model fit was obtained compared to D5. The differences in biomagnification behavior between D5 and the legacy contaminants suggest that the biomagnification of D5 is being governed by species-specific properties such as biotransformation rate or tissue distribution that differ from those of legacy contaminants.

  11. Peanut Product Recalls

    Data.gov (United States)

    U.S. Department of Health & Human Services — This list includes human and pet food subject to recall in the United States since January 2009 related to peanut products distributed by Peanut Corporation of...

  12. Climate change-contaminant interactions in marine food webs: Toward a conceptual framework.

    Science.gov (United States)

    Alava, Juan José; Cheung, William W L; Ross, Peter S; Sumaila, U Rashid

    2017-10-01

    Climate change is reshaping the way in which contaminants move through the global environment, in large part by changing the chemistry of the oceans and affecting the physiology, health, and feeding ecology of marine biota. Climate change-associated impacts on structure and function of marine food webs, with consequent changes in contaminant transport, fate, and effects, are likely to have significant repercussions to those human populations that rely on fisheries resources for food, recreation, or culture. Published studies on climate change-contaminant interactions with a focus on food web bioaccumulation were systematically reviewed to explore how climate change and ocean acidification may impact contaminant levels in marine food webs. We propose here a conceptual framework to illustrate the impacts of climate change on contaminant accumulation in marine food webs, as well as the downstream consequences for ecosystem goods and services. The potential impacts on social and economic security for coastal communities that depend on fisheries for food are discussed. Climate change-contaminant interactions may alter the bioaccumulation of two priority contaminant classes: the fat-soluble persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), as well as the protein-binding methylmercury (MeHg). These interactions include phenomena deemed to be either climate change dominant (i.e., climate change leads to an increase in contaminant exposure) or contaminant dominant (i.e., contamination leads to an increase in climate change susceptibility). We illustrate the pathways of climate change-contaminant interactions using case studies in the Northeastern Pacific Ocean. The important role of ecological and food web modeling to inform decision-making in managing ecological and human health risks of chemical pollutants contamination under climate change is also highlighted. Finally, we identify the need to develop integrated policies that manage the

  13. Plankton food-webs: to what extent can they be simplified?

    Directory of Open Access Journals (Sweden)

    Domenico D'Alelio

    2016-05-01

    Full Text Available Plankton is a hugely diverse community including both unicellular and multicellular organisms, whose individual dimensions span over seven orders of magnitude. Plankton is a fundamental part of biogeochemical cycles and food-webs in aquatic systems. While knowledge has progressively accumulated at the level of single species and single trophic processes, the overwhelming biological diversity of plankton interactions is insufficiently known and a coherent and unifying trophic framework is virtually lacking. We performed an extensive review of the plankton literature to provide a compilation of data suitable for implementing food-web models including plankton trophic processes at high taxonomic resolution. We identified the components of the plankton community at the Long Term Ecological Research Station MareChiara in the Gulf of Naples. These components represented the sixty-three nodes of a plankton food-web. To each node we attributed biomass and vital rates, i.e. production, consumption, assimilation rates and ratio between autotrophy and heterotrophy in mixotrophic protists. Biomasses and rates values were defined for two opposite system’s conditions; relatively eutrophic and oligotrophic states. We finally identified 817 possible trophic links within the web and provided each of them with a relative weight, in order to define a diet-matrix, valid for both trophic states, which included all consumers, fromn anoflagellates to carnivorous plankton. Vital rates for plankton resulted, as expected, very wide; this strongly contrasts with the narrow ranges considered in plankton system models implemented so far. Moreover, the amount and variety of trophic links highlighted by our review is largely excluded by state-of-the-art biogeochemical and food-web models for aquatic systems. Plankton models could potentially benefit from the integration of the trophic diversity outlined in this paper: first, by using more realistic rates; second, by better

  14. Pistachio Product Recalls

    Data.gov (United States)

    U.S. Department of Health & Human Services — This list includes food subject to recall in the United States since March 2009 related to pistachios distributed by Setton Pistachio of Terra Bella, Inc. The FDA...

  15. Food-Web Complexity in Guaymas Basin Hydrothermal Vents and Cold Seeps.

    Directory of Open Access Journals (Sweden)

    Marie Portail

    Full Text Available In the Guaymas Basin, the presence of cold seeps and hydrothermal vents in close proximity, similar sedimentary settings and comparable depths offers a unique opportunity to assess and compare the functioning of these deep-sea chemosynthetic ecosystems. The food webs of five seep and four vent assemblages were studied using stable carbon and nitrogen isotope analyses. Although the two ecosystems shared similar potential basal sources, their food webs differed: seeps relied predominantly on methanotrophy and thiotrophy via the Calvin-Benson-Bassham (CBB cycle and vents on petroleum-derived organic matter and thiotrophy via the CBB and reductive tricarboxylic acid (rTCA cycles. In contrast to symbiotic species, the heterotrophic fauna exhibited high trophic flexibility among assemblages, suggesting weak trophic links to the metabolic diversity of chemosynthetic primary producers. At both ecosystems, food webs did not appear to be organised through predator-prey links but rather through weak trophic relationships among co-occurring species. Examples of trophic or spatial niche differentiation highlighted the importance of species-sorting processes within chemosynthetic ecosystems. Variability in food web structure, addressed through Bayesian metrics, revealed consistent trends across ecosystems. Food-web complexity significantly decreased with increasing methane concentrations, a common proxy for the intensity of seep and vent fluid fluxes. Although high fluid-fluxes have the potential to enhance primary productivity, they generate environmental constraints that may limit microbial diversity, colonisation of consumers and the structuring role of competitive interactions, leading to an overall reduction of food-web complexity and an increase in trophic redundancy. Heterogeneity provided by foundation species was identified as an additional structuring factor. According to their biological activities, foundation species may have the potential to

  16. The web-buffet--development and validation of an online tool to measure food choice.

    Science.gov (United States)

    Bucher, Tamara; Keller, Carmen

    2015-08-01

    To date, no data exist on the agreement of food choice measured using an online tool with subsequent actual consumption. This needs to be shown before food choice, measured by means of an online tool, is used as a dependent variable to examine intake in the general population. A 'web-buffet' was developed to assess food choice. Choice was measured as planned meal composition from photographic material; respondents chose preferred foods and proportions for a main meal (out of a possible 144 combinations) online and the validity was assessed by comparison of a meal composed from a web-buffet with actual food intake 24-48 h later. Furthermore, correlations of food preferences, energy needs and health interest with meals chosen from the web-buffet were analysed. Students: n 106 (Study I), n 32 (Study II). Meals chosen from the web-buffet (mean = 2998 kJ, SD = 471 kJ) agreed with actual consumption (rs = 0.63, P choice in the web-buffet agrees sufficiently well with actual intake to measure food choice as a dependent variable in online surveys. However, we found an average underestimation of subsequent consumption. High correlations of preferences with chosen amounts and an inverse association of health interest with total energy further indicate the validity of the tool. Applications in behavioural nutrition research are discussed.

  17. IMPORTANCE OF TEMPERATURE IN MODELLING PCB BIOACCUMULATION IN THE LAKE MICHIGAN FOOD WEB

    Science.gov (United States)

    In most food web models, the exposure temperature of a food web is typically defined using a single spatial compartment. This essentially assumes that the predator and prey are exposed to the same temperature. However, in a large water body such as Lake Michigan, due to the spati...

  18. Assessing ecosystem effects of reservoir operations using food web-energy transfer and water quality models

    Science.gov (United States)

    Saito, L.; Johnson, B.M.; Bartholow, J.; Hanna, R.B.

    2001-01-01

    We investigated the effects on the reservoir food web of a new temperature control device (TCD) on the dam at Shasta Lake, California. We followed a linked modeling approach that used a specialized reservoir water quality model to forecast operation-induced changes in phytoplankton production. A food web–energy transfer model was also applied to propagate predicted changes in phytoplankton up through the food web to the predators and sport fishes of interest. The food web–energy transfer model employed a 10% trophic transfer efficiency through a food web that was mapped using carbon and nitrogen stable isotope analysis. Stable isotope analysis provided an efficient and comprehensive means of estimating the structure of the reservoir's food web with minimal sampling and background data. We used an optimization procedure to estimate the diet proportions of all food web components simultaneously from their isotopic signatures. Some consumers were estimated to be much more sensitive than others to perturbations to phytoplankton supply. The linked modeling approach demonstrated that interdisciplinary efforts enhance the value of information obtained from studies of managed ecosystems. The approach exploited the strengths of engineering and ecological modeling methods to address concerns that neither of the models could have addressed alone: (a) the water quality model could not have addressed quantitatively the possible impacts to fish, and (b) the food web model could not have examined how phytoplankton availability might change due to reservoir operations.

  19. 9 CFR 381.311 - Recall procedure.

    Science.gov (United States)

    2010-01-01

    ... CERTIFICATION POULTRY PRODUCTS INSPECTION REGULATIONS Canning and Canned Products § 381.311 Recall procedure... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Recall procedure. 381.311 Section 381.311 Animals and Animal Products FOOD SAFETY AND INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE AGENCY...

  20. Parasites in the Wadden Sea food web

    NARCIS (Netherlands)

    Thieltges, D.W.; Engelsma, M.Y.; Wendling, C.C.; Wegner, K.M.

    2013-01-01

    While the free-living fauna of the Wadden Sea has received much interest, little is known on the distribution and effects of parasites in the Wadden Sea food web. However, recent studies on this special type of trophic interaction indicate a high diversity of parasites in the Wadden Sea and suggest

  1. Ecosystem Food Web Lift-The-Flap Pages

    Science.gov (United States)

    Atwood-Blaine, Dana; Rule, Audrey C.; Morgan, Hannah

    2016-01-01

    In the lesson on which this practical article is based, third grade students constructed a "lift-the-flap" page to explore food webs on the prairie. The moveable papercraft focused student attention on prairie animals' external structures and how the inferred functions of those structures could support further inferences about the…

  2. Soil food web properties explain ecosystem services across European land use systems.

    Science.gov (United States)

    de Vries, Franciska T; Thébault, Elisa; Liiri, Mira; Birkhofer, Klaus; Tsiafouli, Maria A; Bjørnlund, Lisa; Bracht Jørgensen, Helene; Brady, Mark Vincent; Christensen, Søren; de Ruiter, Peter C; d'Hertefeldt, Tina; Frouz, Jan; Hedlund, Katarina; Hemerik, Lia; Hol, W H Gera; Hotes, Stefan; Mortimer, Simon R; Setälä, Heikki; Sgardelis, Stefanos P; Uteseny, Karoline; van der Putten, Wim H; Wolters, Volkmar; Bardgett, Richard D

    2013-08-27

    Intensive land use reduces the diversity and abundance of many soil biota, with consequences for the processes that they govern and the ecosystem services that these processes underpin. Relationships between soil biota and ecosystem processes have mostly been found in laboratory experiments and rarely are found in the field. Here, we quantified, across four countries of contrasting climatic and soil conditions in Europe, how differences in soil food web composition resulting from land use systems (intensive wheat rotation, extensive rotation, and permanent grassland) influence the functioning of soils and the ecosystem services that they deliver. Intensive wheat rotation consistently reduced the biomass of all components of the soil food web across all countries. Soil food web properties strongly and consistently predicted processes of C and N cycling across land use systems and geographic locations, and they were a better predictor of these processes than land use. Processes of carbon loss increased with soil food web properties that correlated with soil C content, such as earthworm biomass and fungal/bacterial energy channel ratio, and were greatest in permanent grassland. In contrast, processes of N cycling were explained by soil food web properties independent of land use, such as arbuscular mycorrhizal fungi and bacterial channel biomass. Our quantification of the contribution of soil organisms to processes of C and N cycling across land use systems and geographic locations shows that soil biota need to be included in C and N cycling models and highlights the need to map and conserve soil biodiversity across the world.

  3. URBANIZATION ALTERS FATTY ACID CONCENTRATIONS OF STREAM FOOD WEBS IN THE NARRAGANSETT BAY WATERSHED

    Science.gov (United States)

    Urbanization and associated human activities negatively affect stream algal and invertebrate assemblages, likely altering food webs. Our goal was to determine if urbanization affects food web essential fatty acids (EFAs) and if EFAs could be useful ecological indicators in monito...

  4. River food web response to large-scale riparian zone manipulations.

    Directory of Open Access Journals (Sweden)

    J Timothy Wootton

    Full Text Available Conservation programs often focus on select species, leading to management plans based on the autecology of the focal species, but multiple ecosystem components can be affected both by the environmental factors impacting, and the management targeting, focal species. These broader effects can have indirect impacts on target species through the web of interactions within ecosystems. For example, human activity can strongly alter riparian vegetation, potentially impacting both economically-important salmonids and their associated river food web. In an Olympic Peninsula river, Washington state, USA, replicated large-scale riparian vegetation manipulations implemented with the long-term (>40 yr goal of improving salmon habitat did not affect water temperature, nutrient limitation or habitat characteristics, but reduced canopy cover, causing reduced energy input via leaf litter, increased incident solar radiation (UV and PAR and increased algal production compared to controls. In response, benthic algae, most insect taxa, and juvenile salmonids increased in manipulated areas. Stable isotope analysis revealed a predominant contribution of algal-derived energy to salmonid diets in manipulated reaches. The experiment demonstrates that riparian management targeting salmonids strongly affects river food webs via changes in the energy base, illustrates how species-based management strategies can have unanticipated indirect effects on the target species via the associated food web, and supports ecosystem-based management approaches for restoring depleted salmonid stocks.

  5. Detrital shadows: estuarine food web connectivity depends on fluvial influence and consumer feeding mode.

    Science.gov (United States)

    Howe, Emily; Simenstad, Charles A; Ogston, Andrea

    2017-10-01

    We measured the influence of landscape setting on estuarine food web connectivity in five macrotidal Pacific Northwest estuaries across a gradient of freshwater influence. We used stable isotopes (δ 13 C, δ 15 N, δ 34 S) in combination with a Bayesian mixing model to trace primary producer contributions to suspension- and deposit-feeding bivalve consumers (Mytilus trossulus and Macoma nasuta) transplanted into three estuarine vegetation zones: emergent marsh, mudflat, and eelgrass. Eelgrass includes both Japanese eelgrass (Zostera japonica) and native eelgrass (Zostera marina). Fluvial discharge and consumer feeding mode strongly influenced the strength and spatial scale of observed food web linkages, while season played a secondary role. Mussels displayed strong cross-ecosystem connectivity in all estuaries, with decreasing marine influence in the more fluvial estuaries. Mussel diets indicated homogenization of detrital sources within the water column of each estuary. In contrast, the diets of benthic deposit-feeding clams indicated stronger compartmentalization in food web connectivity, especially in the largest river delta where clam diets were trophically disconnected from marsh sources of detritus. This suggests detritus deposition is patchy across space, and less homogenous than the suspended detritus pool. In addition to fluvial setting, other estuary-specific environmental drivers, such as marsh area or particle transport speed, influenced the degree of food web linkages across space and time, often accounting for unexpected patterns in food web connectivity. Transformations of the estuarine landscape that alter river hydrology or availability of detritus sources can thus potentially disrupt natural food web connectivity at the landscape scale, especially for sedentary organisms, which cannot track their food sources through space. © 2017 by the Ecological Society of America.

  6. Reproducibility of two, three, four and five 24-hour recalls in peri ...

    African Journals Online (AJOL)

    2011-06-10

    Jun 10, 2011 ... participants' ability to accurately record or recall food consumption, describe food .... used.16 The accuracy of food item and portion size data captured for ..... Four 24-hour recalls are more practical and cost-effective, and carry.

  7. The added value of food frequency questionnaire (FFQ) information to estimate the usual food intake based on repeated 24-hour recalls.

    Science.gov (United States)

    Ost, Cloë; De Ridder, Karin A A; Tafforeau, Jean; Van Oyen, Herman

    2017-01-01

    Statistical methods to model the usual dietary intake of foods in a population generally ignore the additional information on the never-consumers. The objective of this study is to determine the added value of Food Frequency Questionnaire (FFQ) data allowing distinguishing the never-consumers from the non-consumers while modeling the usual intake distribution. Three food items with a different proportion of never-consumers were selected from the database of the Belgian food consumption survey of 2004 ( N  = 3200). The usual intake distribution for these food items was modeled with the Statistical Program for Analysis of Dietary Exposure (SPADE) and modeling parameters were extracted. These parameters were used to simulate (a) a new database with two 24-h recalls per respondent and (b) a "true" usual intake distribution. The usual intake distribution from the new database was obtained by modeling the 24-h recalls with SPADE, once without and once with the inclusion of the FFQ data on the never-consumers. Ratios were calculated for the different percentiles of the usual intake distribution: the modeled usual intake (g/day) (for both SPADE with and without the inclusion of FFQ data on never-consumers) was divided by the corresponding percentile of the simulated "true" usual intake (g/day). The closer the ratio is to one, the better the model fits the data. Inclusion of the FFQ information to identify the never-consumers did not improve the estimation of the higher percentiles of the usual intake distribution. However, taking into account this FFQ information improved the estimation of the lower percentiles of the usual intake distribution even when the proportion of never-consumers was low. The inclusion of FFQ information to identify the never-consumers is beneficial when interested in the whole usual intake distribution or in the lower percentiles only, no matter how low the proportion of never-consumers for that food item may be. However, when interest is only in

  8. Towards a framework for assessment and management of cumulative human impacts on marine food webs.

    Science.gov (United States)

    Giakoumi, Sylvaine; Halpern, Benjamin S; Michel, Loïc N; Gobert, Sylvie; Sini, Maria; Boudouresque, Charles-François; Gambi, Maria-Cristina; Katsanevakis, Stelios; Lejeune, Pierre; Montefalcone, Monica; Pergent, Gerard; Pergent-Martini, Christine; Sanchez-Jerez, Pablo; Velimirov, Branko; Vizzini, Salvatrice; Abadie, Arnaud; Coll, Marta; Guidetti, Paolo; Micheli, Fiorenza; Possingham, Hugh P

    2015-08-01

    Effective ecosystem-based management requires understanding ecosystem responses to multiple human threats, rather than focusing on single threats. To understand ecosystem responses to anthropogenic threats holistically, it is necessary to know how threats affect different components within ecosystems and ultimately alter ecosystem functioning. We used a case study of a Mediterranean seagrass (Posidonia oceanica) food web and expert knowledge elicitation in an application of the initial steps of a framework for assessment of cumulative human impacts on food webs. We produced a conceptual seagrass food web model, determined the main trophic relationships, identified the main threats to the food web components, and assessed the components' vulnerability to those threats. Some threats had high (e.g., coastal infrastructure) or low impacts (e.g., agricultural runoff) on all food web components, whereas others (e.g., introduced carnivores) had very different impacts on each component. Partitioning the ecosystem into its components enabled us to identify threats previously overlooked and to reevaluate the importance of threats commonly perceived as major. By incorporating this understanding of system vulnerability with data on changes in the state of each threat (e.g., decreasing domestic pollution and increasing fishing) into a food web model, managers may be better able to estimate and predict cumulative human impacts on ecosystems and to prioritize conservation actions. © 2015 Society for Conservation Biology.

  9. 75 FR 3355 - Guidelines and Requirements for Mandatory Recall Notices

    Science.gov (United States)

    2010-01-21

    ... they know have an interest in receiving the information in order to take advantage of social networking... 20814; telephone (301) 504-7520. SUPPLEMENTARY INFORMATION: I. Introduction In the Federal Register of... Handbook. Recall templates and a recall checklist are also available to the public on the CPSC's Web site...

  10. Climate change alters the structure of arctic marine food webs due to poleward shifts of boreal generalists.

    Science.gov (United States)

    Kortsch, Susanne; Primicerio, Raul; Fossheim, Maria; Dolgov, Andrey V; Aschan, Michaela

    2015-09-07

    Climate-driven poleward shifts, leading to changes in species composition and relative abundances, have been recently documented in the Arctic. Among the fastest moving species are boreal generalist fish which are expected to affect arctic marine food web structure and ecosystem functioning substantially. Here, we address structural changes at the food web level induced by poleward shifts via topological network analysis of highly resolved boreal and arctic food webs of the Barents Sea. We detected considerable differences in structural properties and link configuration between the boreal and the arctic food webs, the latter being more modular and less connected. We found that a main characteristic of the boreal fish moving poleward into the arctic region of the Barents Sea is high generalism, a property that increases connectance and reduces modularity in the arctic marine food web. Our results reveal that habitats form natural boundaries for food web modules, and that generalists play an important functional role in coupling pelagic and benthic modules. We posit that these habitat couplers have the potential to promote the transfer of energy and matter between habitats, but also the spread of pertubations, thereby changing arctic marine food web structure considerably with implications for ecosystem dynamics and functioning. © 2015 The Authors.

  11. Impact of global changes and biotic interactions on food webs in lakes

    DEFF Research Database (Denmark)

    Vidal, Nicolas

    for irrigation leads to enhanced salinisation in many aquatic systems. A consequent disappearance of higher trophic positions (mostly fish) resulted in reduced food web complexity (paper 2). Human direct and indirect modifications, in addition to climate change, may alter the current biogeographic distribution...... and the functioning of shallow lakes, with particular emphasis on enhanced air temperatures (objective 1), salinisation (objective 2) and species invasions (objective 3). A stable isotope approach and stomach content analyses of fish were used in order to characterise the food web structure, combined with structure......, accordingly, stronger cascading effects on the lower trophic levels could be traced in the Azorean lakes. However, in contrast to expectations, no effect on the trophic position of fish was found, but the shape of the food web structure was more triangular in the (cold) Faroese lakes that were also...

  12. Bioaccumulation and trophic transfer of perfluorinated compounds in a eutrophic freshwater food web

    International Nuclear Information System (INIS)

    Xu, Jian; Guo, Chang-Sheng; Zhang, Yuan; Meng, Wei

    2014-01-01

    In this study, the bioaccumulation of perfluorinated compounds from a food web in Taihu Lake in China was investigated. The organisms included egret bird species, carnivorous fish, omnivorous fish, herbivorous fish, zooplankton, phytoplankton, zoobenthos and white shrimp. Isotope analysis by δ 13 C and δ 15 N indicated that the carnivorous fish and egret were the top predators in the studied web, occupying trophic levels intermediate between 3.66 and 4.61, while plankton was at the lowest trophic level. Perfluorinated carboxylates (PFCAs) with 9–12 carbons were significantly biomagnified, with trophic magnification factors (TMFs) ranging from 2.1 to 3.7. The TMF of perfluorooctane sulfonate (PFOS) (2.9) was generally comparable to or lower than those of the PFCAs in the same food web. All hazard ratio (HR) values reported for PFOS and perfluorooctanoate (PFOA) were less than unity, suggesting that the detected levels would not cause any immediate health effects to the people in Taihu Lake region through the consumption of shrimps and fish. -- Highlights: • Biomagnification of PFCs in the food web of a eutrophic freshwater lake was studied. • Carnivorous fish and egret were the top predators while plankton was at the lowest trophic level. • PFCAs with 9–12 carbons were significantly biomagnified. • TMF of PFOS was comparable to or lower than those of the PFCAs in the same food web. • PFOS and PFOA would not cause health effects to the people via diet consumption. -- PFCs were found to be bioaccumulated and biomagnified in a food web from a eutrophic freshwater lake in subtropical area

  13. Development of a multichemical food web model: application to PBDEs in Lake Ellasjoen, Bear Island, Norway.

    Science.gov (United States)

    Gandhi, Nilima; Bhavsar, Satyendra P; Gewurtz, Sarah B; Diamond, Miriam L; Evenset, Anita; Christensen, Guttorm N; Gregor, Dennis

    2006-08-01

    A multichemical food web model has been developed to estimate the biomagnification of interconverting chemicals in aquatic food webs. We extended a fugacity-based food web model for single chemicals to account for reversible and irreversible biotransformation among a parent chemical and transformation products, by simultaneously solving mass balance equations of the chemicals using a matrix solution. The model can be applied to any number of chemicals and organisms or taxonomic groups in a food web. The model was illustratively applied to four PBDE congeners, BDE-47, -99, -100, and -153, in the food web of Lake Ellasjøen, Bear Island, Norway. In Ellasjøen arctic char (Salvelinus alpinus), the multichemical model estimated PBDE biotransformation from higher to lower brominated congeners and improved the correspondence between estimated and measured concentrations in comparison to estimates from the single-chemical food web model. The underestimation of BDE-47, even after considering bioformation due to biotransformation of the otherthree congeners, suggests its formation from additional biotransformation pathways not considered in this application. The model estimates approximate values for congener-specific biotransformation half-lives of 5.7,0.8,1.14, and 0.45 years for BDE-47, -99, -100, and -153, respectively, in large arctic char (S. alpinus) of Lake Ellasjøen.

  14. Anthropogenic and natural sources of acidity and metals and their influence on the structure of stream food webs.

    Science.gov (United States)

    Hogsden, Kristy L; Harding, Jon S

    2012-03-01

    We compared food web structure in 20 streams with either anthropogenic or natural sources of acidity and metals or circumneutral water chemistry in New Zealand. Community and diet analysis indicated that mining streams receiving anthropogenic inputs of acidic and metal-rich drainage had much simpler food webs (fewer species, shorter food chains, less links) than those in naturally acidic, naturally high metal, and circumneutral streams. Food webs of naturally high metal streams were structurally similar to those in mining streams, lacking fish predators and having few species. Whereas, webs in naturally acidic streams differed very little from those in circumneutral streams due to strong similarities in community composition and diets of secondary and top consumers. The combined negative effects of acidity and metals on stream food webs are clear. However, elevated metal concentrations, regardless of source, appear to play a more important role than acidity in driving food web structure. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Interaction strength combinations and the overfishing of a marine food web.

    Science.gov (United States)

    Bascompte, Jordi; Melián, Carlos J; Sala, Enric

    2005-04-12

    The stability of ecological communities largely depends on the strength of interactions between predators and their prey. Here we show that these interaction strengths are structured nonrandomly in a large Caribbean marine food web. Specifically, the cooccurrence of strong interactions on two consecutive levels of food chains occurs less frequently than expected by chance. Even when they occur, these strongly interacting chains are accompanied by strong omnivory more often than expected by chance. By using a food web model, we show that these interaction strength combinations reduce the likelihood of trophic cascades after the overfishing of top predators. However, fishing selectively removes predators that are overrepresented in strongly interacting chains. Hence, the potential for strong community-wide effects remains a threat.

  16. Deep pelagic food web structure as revealed by in situ feeding observations.

    Science.gov (United States)

    Choy, C Anela; Haddock, Steven H D; Robison, Bruce H

    2017-12-06

    Food web linkages, or the feeding relationships between species inhabiting a shared ecosystem, are an ecological lens through which ecosystem structure and function can be assessed, and thus are fundamental to informing sustainable resource management. Empirical feeding datasets have traditionally been painstakingly generated from stomach content analysis, direct observations and from biochemical trophic markers (stable isotopes, fatty acids, molecular tools). Each approach carries inherent biases and limitations, as well as advantages. Here, using 27 years (1991-2016) of in situ feeding observations collected by remotely operated vehicles (ROVs), we quantitatively characterize the deep pelagic food web of central California within the California Current, complementing existing studies of diet and trophic interactions with a unique perspective. Seven hundred and forty-three independent feeding events were observed with ROVs from near-surface waters down to depths approaching 4000 m, involving an assemblage of 84 different predators and 82 different prey types, for a total of 242 unique feeding relationships. The greatest diversity of prey was consumed by narcomedusae, followed by physonect siphonophores, ctenophores and cephalopods. We highlight key interactions within the poorly understood 'jelly web', showing the importance of medusae, ctenophores and siphonophores as key predators, whose ecological significance is comparable to large fish and squid species within the central California deep pelagic food web. Gelatinous predators are often thought to comprise relatively inefficient trophic pathways within marine communities, but we build upon previous findings to document their substantial and integral roles in deep pelagic food webs. © 2017 The Authors.

  17. Internet food marketing strategies aimed at children and adolescents: a content analysis of food and beverage brand web sites.

    Science.gov (United States)

    Weber, Kristi; Story, Mary; Harnack, Lisa

    2006-09-01

    Americans are spending an increasing amount of time using "new media" like the Internet. There has been little research examining food and beverage Web sites' content and marketing practices, especially those that attract children and adolescents. The purpose of this study was to conduct a content analysis of food- and beverage-brand Web sites and the marketing techniques and advertising strategies present on these sites. The top five brands in eight food and beverage categories, 40 brands in total, were selected based on annual sales data from Brandweek magazine's annual "Superbrands" report. Data were collected using a standardized coding form. The results show a wide variety of Internet marketing techniques and advertising strategies targeting children and adolescents. "Advergaming" (games in which the advertised product is part of the game) was present on 63% of the Web sites. Half or more of the Web sites used cartoon characters (50%) or spokescharacters (55%), or had a specially designated children's area (58%) with a direct link from the homepage. With interactive media still in its developmental stage, there is a need to develop safeguards for children. Food and nutrition professionals need to advocate for responsible marketing techniques that will support the health of children.

  18. The structure of salt marsh soil mesofauna food webs - The prevalence of disturbance.

    Science.gov (United States)

    Haynert, Kristin; Kiggen, Mirijam; Klarner, Bernhard; Maraun, Mark; Scheu, Stefan

    2017-01-01

    Mesofauna taxa fill key trophic positions in soil food webs, even in terrestrial-marine boundary habitats characterized by frequent natural disturbances. Salt marshes represent such boundary habitats, characterized by frequent inundations increasing from the terrestrial upper to the marine pioneer zone. Despite the high abundance of soil mesofauna in salt marshes and their important function by facilitating energy and carbon flows, the structure, trophic ecology and habitat-related diet shifts of mesofauna species in natural salt marsh habitats is virtually unknown. Therefore, we investigated the effects of natural disturbance (inundation frequency) on community structure, food web complexity and resource use of soil mesofauna using stable isotope analysis (15N, 13C) in three salt marsh zones. In this intertidal habitat, the pioneer zone is exposed to inundations twice a day, but lower and upper salt marshes are less frequently inundated based on shore height. The mesofauna comprised 86 species / taxa dominated by Collembola, Oribatida and Mesostigmata. Shifts in environmental disturbances influenced the structure of food webs, diversity and density declined strongly from the land to the sea pointing to the importance of increasing levels of inundation frequency. Accordingly, the reduced diversity and density was associated by a simplification of the food web in the pioneer zone as compared to the less inundated lower and upper salt marsh with a higher number of trophic levels. Strong variations in δ15N signatures demonstrated that mesofauna species are feeding at multiple trophic levels. Primary decomposers were low and most mesofauna species functioned as secondary decomposers or predators including second order predators or scavengers. The results document that major decomposer taxa, such as Collembola and Oribatida, are more diverse than previously assumed and predominantly dwell on autochthonous resources of the respective salt marsh zone. The results further

  19. Tracing organophosphorus and brominated flame retardants and plasticizers in an estuarine food web.

    Science.gov (United States)

    Brandsma, Sicco H; Leonards, Pim E G; Leslie, Heather A; de Boer, Jacob

    2015-02-01

    Nine organophosphorus flame retardants (PFRs) were detected in a pelagic and benthic food web of the Western Scheldt estuary, The Netherlands. Concentrations of several PFRs were an order of magnitude higher than those of the brominated flame retardants (BFRs). However, the detection frequency of the PFRs (6-56%) was lower than that of the BFRs (50-97%). Tris(2-butoxyethyl) phosphate (TBOEP), tris(isobutyl) phosphate (TIBP) and tris(2-chloroisopropyl) phosphate (TCIPP) were the dominant PFRs in sediment with median concentrations of 7.0, 8.1 and 1.8 ng/g dry weight (dw), respectively. PFR levels in the suspended particular matter (SPM) were 2-12 times higher than that in sediment. TBOEP, TCIPP, TIBP, tris(2-chloroethyl) phosphate (TCEP) and tris(phenyl) phosphate (TPHP) were found in organisms higher in the estuarine food web. The highest PFR concentrations in the benthic food web were found in sculpin, goby and lugworm with median concentrations of 17, 7.4, 4.6 and 2.0 ng/g wet weight (ww) for TBOEP, TIBP, TCIPP and TPHP, respectively. Comparable levels were observed in the pelagic food web, BDE209 was the predominant PBDE in sediment and SPM with median concentrations up to 9.7 and 385 ng/g dw, respectively. BDE47 was predominant in the biotic compartment of the food web with highest median levels observed in sculpin and common tern eggs of 79 ng/g lipid weight (lw) (2.5 ng/g ww) and 80 ng/g lw (11 ng/g ww), respectively. Trophic magnification was observed for all PBDEs with the exception of BDE209. Indications of trophic magnification of PFRs were observed in the benthic food web for TBOEP, TCIPP and TCEP with tentative trophic magnification factors of 3.5, 2.2 and 2.6, respectively (pwebs. The relative high PFR levels in several fish species suggest high emissions and substantial exposure of organisms to PFRs in the Western Scheldt. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Food web changes under ocean acidification promote herring larvae survival.

    Science.gov (United States)

    Sswat, Michael; Stiasny, Martina H; Taucher, Jan; Algueró-Muñiz, Maria; Bach, Lennart T; Jutfelt, Fredrik; Riebesell, Ulf; Clemmesen, Catriona

    2018-05-01

    Ocean acidification-the decrease in seawater pH due to rising CO 2 concentrations-has been shown to lower survival in early life stages of fish and, as a consequence, the recruitment of populations including commercially important species. To date, ocean-acidification studies with fish larvae have focused on the direct physiological impacts of elevated CO 2 , but largely ignored the potential effects of ocean acidification on food web interactions. In an in situ mesocosm study on Atlantic herring (Clupea harengus) larvae as top predators in a pelagic food web, we account for indirect CO 2 effects on larval survival mediated by changes in food availability. The community was exposed to projected end-of-the-century CO 2 conditions (~760 µatm pCO 2 ) over a period of 113 days. In contrast with laboratory studies that reported a decrease in fish survival, the survival of the herring larvae in situ was significantly enhanced by 19 ± 2%. Analysis of the plankton community dynamics suggested that the herring larvae benefitted from a CO 2 -stimulated increase in primary production. Such indirect effects may counteract the possible direct negative effects of ocean acidification on the survival of fish early life stages. These findings emphasize the need to assess the food web effects of ocean acidification on fish larvae before we can predict even the sign of change in fish recruitment in a high-CO 2 ocean.

  1. Warming alters energetic structure and function but not resilience of soil food webs

    Science.gov (United States)

    Schwarz, Benjamin; Barnes, Andrew D.; Thakur, Madhav P.; Brose, Ulrich; Ciobanu, Marcel; Reich, Peter B.; Rich, Roy L.; Rosenbaum, Benjamin; Stefanski, Artur; Eisenhauer, Nico

    2017-12-01

    Climate warming is predicted to alter the structure, stability, and functioning of food webs1-5. Yet, despite the importance of soil food webs for energy and nutrient turnover in terrestrial ecosystems, the effects of warming on these food webs—particularly in combination with other global change drivers—are largely unknown. Here, we present results from two complementary field experiments that test the interactive effects of warming with forest canopy disturbance and drought on energy flux in boreal-temperate ecotonal forest soil food webs. The first experiment applied a simultaneous above- and belowground warming treatment (ambient, +1.7 °C, +3.4 °C) to closed-canopy and recently clear-cut forest, simulating common forest disturbance6. The second experiment crossed warming with a summer drought treatment (-40% rainfall) in the clear-cut habitats. We show that warming reduces energy flux to microbes, while forest canopy disturbance and drought facilitates warming-induced increases in energy flux to higher trophic levels and exacerbates the reduction in energy flux to microbes, respectively. Contrary to expectations, we find no change in whole-network resilience to perturbations, but significant losses in ecosystem functioning. Warming thus interacts with forest disturbance and drought, shaping the energetic structure of soil food webs and threatening the provisioning of multiple ecosystem functions in boreal-temperate ecotonal forests.

  2. Quantity and quality: unifying food web and ecosystem perspectives on the role of resource subsidies in freshwaters.

    Science.gov (United States)

    Marcarelli, Amy M; Baxter, Colden V; Mineau, Madeleine M; Hall, Robert O

    2011-06-01

    Although the study of resource subsidies has emerged as a key topic in both ecosystem and food web ecology, the dialogue over their role has been limited by separate approaches that emphasize either subsidy quantity or quality. Considering quantity and quality together may provide a simple, but previously unexplored, framework for identifying the mechanisms that govern the importance of subsidies for recipient food webs and ecosystems. Using a literature review of > 90 studies of open-water metabolism in lakes and streams, we show that high-flux, low-quality subsidies can drive freshwater ecosystem dynamics. Because most of these ecosystems are net heterotrophic, allochthonous inputs must subsidize respiration. Second, using a literature review of subsidy quality and use, we demonstrate that animals select for high-quality food resources in proportions greater than would be predicted based on food quantity, and regardless of allochthonous or autochthonous origin. This finding suggests that low-flux, high-quality subsidies may be selected for by animals, and in turn may disproportionately affect food web and ecosystem processes (e.g., animal production, trophic energy or organic matter flow, trophic cascades). We then synthesize and review approaches that evaluate the role of subsidies and explicitly merge ecosystem and food web perspectives by placing food web measurements in the context of ecosystem budgets, by comparing trophic and ecosystem production and fluxes, and by constructing flow food webs. These tools can and should be used to address future questions about subsidies, such as the relative importance of subsidies to different trophic levels and how subsidies may maintain or disrupt ecosystem stability and food web interactions.

  3. Modeling the impact of oyster culture on a mudflat food web in Marennes-Oleron Bay (France)

    OpenAIRE

    Leguerrier, D; Niquil, Nathalie; Petiau, A; Bodoy, Alain

    2004-01-01

    We used a carbon-based food web model to investigate the effects of oyster cultivation on the ecosystem of an intertidal mudflat. A previously published food web model of a mudflat in Marennes-Oleron Bay, France, was updated with revised parameters, and a realistic surface area and density of existing oyster cultures on the mudflat. We developed 2 hypothetical scenarios to estimate the impact of oyster cultivation on the food web structure of the ecosystem: one with no oysters, the other with...

  4. Matching consumer feeding behaviours and resource traits: a fourth-corner problem in food-web theory.

    Science.gov (United States)

    Monteiro, Angelo Barbosa; Faria, Lucas Del Bianco

    2018-06-06

    For decades, food web theory has proposed phenomenological models for the underlying structure of ecological networks. Generally, these models rely on latent niche variables that match the feeding behaviour of consumers with their resource traits. In this paper, we used a comprehensive database to evaluate different hypotheses on the best dependency structure of trait-matching patterns between consumers and resource traits. We found that consumer feeding behaviours had complex interactions with resource traits; however, few dimensions (i.e. latent variables) could reproduce the trait-matching patterns. We discuss our findings in the light of three food web models designed to reproduce the multidimensionality of food web data; additionally, we discuss how using species traits clarify food webs beyond species pairwise interactions and enable studies to infer ecological generality at larger scales, despite potential taxonomic differences, variations in ecological conditions and differences in species abundance between communities. © 2018 John Wiley & Sons Ltd/CNRS.

  5. FoodPro: A Web-Based Tool for Evaluating Covariance and Correlation NMR Spectra Associated with Food Processes

    Directory of Open Access Journals (Sweden)

    Eisuke Chikayama

    2016-10-01

    Full Text Available Foods from agriculture and fishery products are processed using various technologies. Molecular mixture analysis during food processing has the potential to help us understand the molecular mechanisms involved, thus enabling better cooking of the analyzed foods. To date, there has been no web-based tool focusing on accumulating Nuclear Magnetic Resonance (NMR spectra from various types of food processing. Therefore, we have developed a novel web-based tool, FoodPro, that includes a food NMR spectrum database and computes covariance and correlation spectra to tasting and hardness. As a result, FoodPro has accumulated 236 aqueous (extracted in D2O and 131 hydrophobic (extracted in CDCl3 experimental bench-top 60-MHz NMR spectra, 1753 tastings scored by volunteers, and 139 hardness measurements recorded by a penetrometer, all placed into a core database. The database content was roughly classified into fish and vegetable groups from the viewpoint of different spectrum patterns. FoodPro can query a user food NMR spectrum, search similar NMR spectra with a specified similarity threshold, and then compute estimated tasting and hardness, covariance, and correlation spectra to tasting and hardness. Querying fish spectra exemplified specific covariance spectra to tasting and hardness, giving positive covariance for tasting at 1.31 ppm for lactate and 3.47 ppm for glucose and a positive covariance for hardness at 3.26 ppm for trimethylamine N-oxide.

  6. FoodPro: A Web-Based Tool for Evaluating Covariance and Correlation NMR Spectra Associated with Food Processes.

    Science.gov (United States)

    Chikayama, Eisuke; Yamashina, Ryo; Komatsu, Keiko; Tsuboi, Yuuri; Sakata, Kenji; Kikuchi, Jun; Sekiyama, Yasuyo

    2016-10-19

    Foods from agriculture and fishery products are processed using various technologies. Molecular mixture analysis during food processing has the potential to help us understand the molecular mechanisms involved, thus enabling better cooking of the analyzed foods. To date, there has been no web-based tool focusing on accumulating Nuclear Magnetic Resonance (NMR) spectra from various types of food processing. Therefore, we have developed a novel web-based tool, FoodPro, that includes a food NMR spectrum database and computes covariance and correlation spectra to tasting and hardness. As a result, FoodPro has accumulated 236 aqueous (extracted in D₂O) and 131 hydrophobic (extracted in CDCl₃) experimental bench-top 60-MHz NMR spectra, 1753 tastings scored by volunteers, and 139 hardness measurements recorded by a penetrometer, all placed into a core database. The database content was roughly classified into fish and vegetable groups from the viewpoint of different spectrum patterns. FoodPro can query a user food NMR spectrum, search similar NMR spectra with a specified similarity threshold, and then compute estimated tasting and hardness, covariance, and correlation spectra to tasting and hardness. Querying fish spectra exemplified specific covariance spectra to tasting and hardness, giving positive covariance for tasting at 1.31 ppm for lactate and 3.47 ppm for glucose and a positive covariance for hardness at 3.26 ppm for trimethylamine N -oxide.

  7. A Mobile Phone Based Method to Assess Energy and Food Intake in Young Children: A Validation Study against the Doubly Labelled Water Method and 24 h Dietary Recalls.

    Science.gov (United States)

    Delisle Nyström, Christine; Forsum, Elisabet; Henriksson, Hanna; Trolle-Lagerros, Ylva; Larsson, Christel; Maddison, Ralph; Timpka, Toomas; Löf, Marie

    2016-01-15

    Mobile phones are becoming important instruments for assessing diet and energy intake. We developed the Tool for Energy Balance in Children (TECH), which uses a mobile phone to assess energy and food intake in pre-school children. The aims of this study were: (a) to compare energy intake (EI) using TECH with total energy expenditure (TEE) measured via doubly labelled water (DLW); and (b) to compare intakes of fruits, vegetables, fruit juice, sweetened beverages, candy, ice cream, and bakery products using TECH with intakes acquired by 24 h dietary recalls. Participants were 39 healthy, Swedish children (5.5 ± 0.5 years) within the ongoing Mobile-based Intervention Intended to Stop Obesity in Preschoolers (MINISTOP) obesity prevention trial. Energy and food intakes were assessed during four days using TECH and 24 h telephone dietary recalls. Mean EI (TECH) was not statistically different from TEE (DLW) (5820 ± 820 kJ/24 h and 6040 ± 680 kJ/24 h, respectively). No significant differences in the average food intakes using TECH and 24 h dietary recalls were found. All food intakes were correlated between TECH and the 24 h dietary recalls (ρ = 0.665-0.896, p foods and thus has the potential to be a useful tool for dietary studies in pre-school children, for example obesity prevention trials.

  8. Mercury and other trace elements in a pelagic Arctic marine food web (Northwater Polynya, Baffin Bay)

    International Nuclear Information System (INIS)

    Campbell, Linda M.; Norstrom, Ross J.; Hobson, Keith A.; Muir, Derek C.G.; Backus, Sean; Fisk, Aaron T.

    2005-01-01

    Total mercury (THg), methylmercury (MeHg) and 22 other trace elements were measured in ice algae, three species of zooplankton, mixed zooplankton samples, Arctic cod (Boreogadus saida), ringed seals (Phoca hispida) and eight species of seabirds to examine the trophodynamics of these metals in an Arctic marine food web. All samples were collected in 1998 in the Northwater Polynya (NOW) located between Ellesmere Island and Greenland in Baffin Bay. THg and MeHg were found to biomagnify through the NOW food web, based on significant positive relationships between log THg and log MeHg concentrations vs. δ 15 N muscle and liver . The slope of these relationships for muscle THg and MeHg concentrations (slope = 0.197 and 0.223, respectively) were similar to those reported for other aquatic food webs. The food web behavior of THg and δ 15 N appears constant, regardless of trophic state (eutrophic vs. oligotrophic), latitude (Arctic vs. tropical) or salinity (marine vs. freshwater) of the ecosystem. Rb in both liver and muscle tissue and Zn in muscle tissue were also found to biomagnify through this food web, although at a rate that is approximately 25% of that of THg. A number of elements (Cd, Pb and Ni in muscle tissue and Cd and Li in seabird liver tissue) were found to decrease trophically through the food web, as indicated by significantly negative relationships with tissue-specific δ 15 N. A diverse group of metals (Ag, Ba, La, Li, Sb, Sr, U and V) were found to have higher concentrations in zooplankton than seabirds or marine mammals due to bioconcentration from seawater. The remaining metals (As, Co, Cu, Ga, Mn, Mo and Se in muscle tissue) showed no relationship with trophic position, as indicated by δ 15 N values, although As in liver tissue showed significant biomagnification in the seabird portion of the food web

  9. Tracing Mississippi River influences in estuarine food webs of coastal Louisiana.

    Science.gov (United States)

    Wissel, Björn; Fry, Brian

    2005-08-01

    The Breton Sound estuary in southern Louisiana receives large amounts of Mississippi River water via a controlled diversion structure at the upstream end of the estuary. We used stable isotopes to trace spatial and seasonal responses of the downstream food web to winter and spring introductions of river water. Analysis of delta13C, delta15N, and delta34S in the common local consumers such as grass shrimp (Palaemonetes sp.), barnacles (Balanus sp.), and small plankton-feeding fish (bay anchovies, Anchoa mitchilli) showed that the diversion was associated with two of the five major source regimes that were supporting food webs: a river regime near the diversion and a river-influenced productive marsh regime farther away from the diversion. Mixing models identified a third river-influenced source regime at the marine end of the estuary where major natural discharge from the Bird's Foot Delta wraps around into estuarine waters. The remaining two source regimes represented typical estuarine conditions: local freshwater sources especially from precipitation and a brackish source regime representing higher salinity marine influences. Overall, the Mississippi River diversion accounted for 75% of food web support in the upper estuary and 25% in the middle estuary, with influence strongest along known flow pathways and closest to the diversion. Isotopes also traced seasonal changes in river contributions, and indicated increased plant community productivity along the major flow path of diversion water. In the Breton Sound estuary, bottom-up forcing of food webs is strongly linked to river introductions and discharge, occurring in spatial and temporal patterns predictable from known river input regimes and known hydrologic circulation patterns.

  10. Sleep deprivation impairs recall of social transmission of food preference in rats

    Directory of Open Access Journals (Sweden)

    Wooden JI

    2014-11-01

    Full Text Available Jessica I Wooden,1,2 Jennifer Pido,1 Hunter Mathews,1 Ryan Kieltyka,1 Bertha Montemayor,1 Christopher P Ward1,3 1Department of Psychology, University of Houston-Clear Lake, 2Department of Psychology, University of Houston, 3Menninger Department of Psychiatry and Behavioral Sciences, Baylor College of Medicine, Houston, TX, USAAbstract: Evidence indicates that sleep plays an important role in learning and memory, and disruption of sleep especially seems to interfere with hippocampal memory processes. Social transmission of food preference (STFP, a natural test of paired associative learning, has been shown to be dependent on the hippocampus. While social transmission of food preference is not a novel task, it has not been used to examine the role of sleep in memory consolidation. Male Sprague-Dawley rats were randomly divided into three groups: cage control; sleep-deprived; and device control. Demonstrator rats were given powdered food mixed with a target spice. Test rats then interacted with demonstrator rats before being given a two choice test of powered food with the target spice or a novel spice. Sleep-deprived rats were then placed in an automated device that prevented sleep for 24 hours. After sleep deprivation, animals were given a preference test again to determine memory for the target spice at both 24 hours and 72 hours. Polysomnography was used to validate the method of sleep deprivation. During immediate preference testing, rats demonstrated a clear preference for the food containing the target spice. Rats that experienced 24 hours of sleep deprivation following the initial testing indicated a significant reduction in the recall of the target spice at 24 and 72 hours. The cage control and device animals maintained their preference for food containing the target spice. Therefore, the loss of sleep interfered with memory consolidation for food preference learned via social transmission.Keywords: hippocampus, learning, consolidation

  11. Lipids of Prokaryotic Origin at the Base of Marine Food Webs

    Directory of Open Access Journals (Sweden)

    Maria José Caramujo

    2012-11-01

    Full Text Available In particular niches of the marine environment, such as abyssal trenches, icy waters and hot vents, the base of the food web is composed of bacteria and archaea that have developed strategies to survive and thrive under the most extreme conditions. Some of these organisms are considered “extremophiles” and modulate the fatty acid composition of their phospholipids to maintain the adequate fluidity of the cellular membrane under cold/hot temperatures, elevated pressure, high/low salinity and pH. Bacterial cells are even able to produce polyunsaturated fatty acids, contrarily to what was considered until the 1990s, helping the regulation of the membrane fluidity triggered by temperature and pressure and providing protection from oxidative stress. In marine ecosystems, bacteria may either act as a sink of carbon, contribute to nutrient recycling to photo-autotrophs or bacterial organic matter may be transferred to other trophic links in aquatic food webs. The present work aims to provide a comprehensive review on lipid production in bacteria and archaea and to discuss how their lipids, of both heterotrophic and chemoautotrophic origin, contribute to marine food webs.

  12. Food and Beverage Brands that Market to Children and Adolescents on the Internet: A Content Analysis of Branded Web Sites

    Science.gov (United States)

    Henry, Anna E.; Story, Mary

    2009-01-01

    Objective: To identify food and beverage brand Web sites featuring designated children's areas, assess marketing techniques present on those industry Web sites, and determine nutritional quality of branded food items marketed to children. Design: Systematic content analysis of food and beverage brand Web sites and nutrient analysis of food and…

  13. Determinants of Web-based CSR Disclosure in the Food Industry

    Directory of Open Access Journals (Sweden)

    Florian Sommer

    2015-01-01

    Full Text Available Purpose –Web-based CSR disclosure provides a variety of advantages for firms. Determining factors for web-based CSR disclosure have been analyzed in several papers. However, only limited research has been conducted on both, the food industry and small and midsized enterprises. This paper is one contribution to fill this gap as we investigate web-based CSR communication of food processors including SME.Design/methodology/approach – We analyzed corporate communication on the websites of 71 food producers from North Rhine-Westphalia, Germany using dictionary-based content analysis. Based on an ordered logit model the relationship between CSR communication and size, profitability, indebtedness and closeness to market was estimated. Economic data were obtained from the commercial database DAFNE.Findings – Our results reveal that larger firms provide relatively more CSR information than smaller firms. There was no significant relationship between CSR disclosure and profitability or indebtedness of a company and an ambiguous relationship with regard to the determinant ‘closeness to market’. Regarding the different areas of communication we found that social compared to environmental aspects were underrepresented.Practical implications – Social aspects of CSR could be used for differentiation in the market. Furthermore, as smaller firms provide relatively less information on CSR it might be worthwhile to analyze the central impediments for CSR communication for those companies.Originality/Value – This paper contributes to the ongoing discussion about firms’ CSR communication. From a convenience sample of 71 food processing firms, including SME, it provides insight regarding the determinants for CSR disclosure on firms’ websites. With the focus on the food industry and the inclusion of SME we contribute with our study to two under-researched areas.

  14. Invasions and extinctions reshape coastal marine food webs.

    Directory of Open Access Journals (Sweden)

    Jarrett E Byrnes

    Full Text Available The biodiversity of ecosystems worldwide is changing because of species loss due to human-caused extinctions and species gain through intentional and accidental introductions. Here we show that the combined effect of these two processes is altering the trophic structure of food webs in coastal marine systems. This is because most extinctions ( approximately 70% occur at high trophic levels (top predators and other carnivores, while most invasions are by species from lower trophic levels (70% macroplanktivores, deposit feeders, and detritivores. These opposing changes thus alter the shape of marine food webs from a trophic pyramid capped by a diverse array of predators and consumers to a shorter, squatter configuration dominated by filter feeders and scavengers. The consequences of the simultaneous loss of diversity at top trophic levels and gain at lower trophic levels is largely unknown. However, current research suggests that a better understanding of how such simultaneous changes in diversity can impact ecosystem function will be required to manage coastal ecosystems and forecast future changes.

  15. The impact of 850,000 years of climate changes on the structure and dynamics of mammal food webs.

    Science.gov (United States)

    Nenzén, Hedvig K; Montoya, Daniel; Varela, Sara

    2014-01-01

    Most evidence of climate change impacts on food webs comes from modern studies and little is known about how ancient food webs have responded to climate changes in the past. Here, we integrate fossil evidence from 71 fossil sites, body-size relationships and actualism to reconstruct food webs for six large mammal communities that inhabited the Iberian Peninsula at different times during the Quaternary. We quantify the long-term dynamics of these food webs and study how their structure changed across the Quaternary, a period for which fossil data and climate changes are well known. Extinction, immigration and turnover rates were correlated with climate changes in the last 850 kyr. Yet, we find differences in the dynamics and structural properties of Pleistocene versus Holocene mammal communities that are not associated with glacial-interglacial cycles. Although all Quaternary mammal food webs were highly nested and robust to secondary extinctions, general food web properties changed in the Holocene. These results highlight the ability of communities to re-organize with the arrival of phylogenetically similar species without major structural changes, and the impact of climate change and super-generalist species (humans) on Iberian Holocene mammal communities.

  16. The impact of 850,000 years of climate changes on the structure and dynamics of mammal food webs.

    Directory of Open Access Journals (Sweden)

    Hedvig K Nenzén

    Full Text Available Most evidence of climate change impacts on food webs comes from modern studies and little is known about how ancient food webs have responded to climate changes in the past. Here, we integrate fossil evidence from 71 fossil sites, body-size relationships and actualism to reconstruct food webs for six large mammal communities that inhabited the Iberian Peninsula at different times during the Quaternary. We quantify the long-term dynamics of these food webs and study how their structure changed across the Quaternary, a period for which fossil data and climate changes are well known. Extinction, immigration and turnover rates were correlated with climate changes in the last 850 kyr. Yet, we find differences in the dynamics and structural properties of Pleistocene versus Holocene mammal communities that are not associated with glacial-interglacial cycles. Although all Quaternary mammal food webs were highly nested and robust to secondary extinctions, general food web properties changed in the Holocene. These results highlight the ability of communities to re-organize with the arrival of phylogenetically similar species without major structural changes, and the impact of climate change and super-generalist species (humans on Iberian Holocene mammal communities.

  17. Ingestion and transfer of microplastics in the planktonic food web

    International Nuclear Information System (INIS)

    Setälä, Outi; Fleming-Lehtinen, Vivi; Lehtiniemi, Maiju

    2014-01-01

    Experiments were carried out with different Baltic Sea zooplankton taxa to scan their potential to ingest plastics. Mysid shrimps, copepods, cladocerans, rotifers, polychaete larvae and ciliates were exposed to 10 μm fluorescent polystyrene microspheres. These experiments showed ingestion of microspheres in all taxa studied. The highest percentage of individuals with ingested spheres was found in pelagic polychaete larvae, Marenzelleria spp. Experiments with the copepod Eurytemora affinis and the mysid shrimp Neomysis integer showed egestion of microspheres within 12 h. Food web transfer experiments were done by offering zooplankton labelled with ingested microspheres to mysid shrimps. Microscopy observations of mysid intestine showed the presence of zooplankton prey and microspheres after 3 h incubation. This study shows for the first time the potential of plastic microparticle transfer via planktonic organisms from one trophic level (mesozooplankton) to a higher level (macrozooplankton). The impacts of plastic transfer and possible accumulation in the food web need further investigations. -- Highlights: • Experiments show the potential of ingestion of plastics by various zooplankton taxa. • This ingestion of plastics can be indirect via other zooplankton organisms. • There may be several alternate routes for microplastic transfer in the food webs. -- Experiments with zooplankton and microspheres showed ingestion of spheres by zpl and the transfer of ingested microspheres to higher trophic level organisms via labelled zooplankton

  18. Radiocobalt cycling in a small mammal food web

    International Nuclear Information System (INIS)

    Willard, W.K.

    1975-01-01

    Cobalt-60 seeping from a nearby radioactive liquid waste trench on the Oak Ridge reservation into a temperate deciduous forest ecosystem provided a source of environmental contamination where its dispersion through a small mammal food web could be studied. Maximum radiocobalt concentrations in the soil were found in the upper 5 cm of 15 cm cores. Transient mammals such as the opossum and the raccoon had small amounts of 60 Co in their tissues (0.5 and 1.0 pCi/gm, respectively), while the permanent mammal residents including the short-tailed shrew (80 pCi/g), white-footed mouse (50 pCi/g), golden mouse (50 pCi/g) and the eastern chipmunk (20 pCi/g) had from 27 to more than 100 times that of the transient mammals. The persistent occurrence of 60 Co in the small mammals tissues indicated its importance in the food web. Of the potential mammalian food items present in the area, only earthworms (Lumbricus rubellus) contained high levels of 60 Co activity (greater than 56 nCi/gm dry wt.). Earthworms collected from the seepage channel eliminated 70 percent of their body burden (gut contents) of 60 Co during the first 24-hour period, but retained the remaining 30 percent (tissue accumulation) for more than 11 weeks. Tissue retention by earthworms and the utilization of numerous burrows by mammals along the seepage channel during the summer months suggested that earthworms constituted a major link in the small mammal food chain. (U.S.)

  19. Hydrological and Biogeochemical Controls on Seasonal and Spatial Differences in Food Webs in the Everglades

    Science.gov (United States)

    Kendall, C.; Wankel, S. D.; Bemis, B. E.; Rawlik, P. S.; Krabbenhoft, D. P.; Lange, T.

    2002-05-01

    Stable isotopes can be used to determine the relative trophic positions of biota within a food web, and to improve our understanding of the biomagnification of contaminants. Plants at the base of the food web uptake dissolved organic carbon (DIC) and nitrogen (DIN) for growth, and their tissue reflects the isotopic composition of these sources. Animals then mirror the isotopic composition of the primary producers, as modified by consumer-diet fractionations at successive trophic steps. During 1995-99, we collected algae, macrophyte, invertebrate, and fish samples from 15 USGS sites in the Everglades and analyzed them for d13C and d15N with the goal of characterizing seasonal and spatial differences in food web relations. Carbon isotopes effectively distinguish between two main types of food webs: ones where algae is the dominant base of the food web, which are characteristic of relatively pristine marsh sites with long hydroperiods, and ones where macrophyte debris appears to be a significant source of nutrients, which are apparently characteristic of shorter hydroperiod sites, and nutrient-impacted marshes and canals. There usually is an inverse relation between d13C and d15N of organisms over time, especially in more pristine environments, reflecting seasonal changes in the d13C of DIC and the d15N of DIN. The d13C and d15N of algae also show strong positive correlations with seasonal changes in water levels. This variability is substantially damped up the food chain, probably because of the longer integration times of animals vs. plants. We speculate that these seasonal shifts in water level result in changes in biogeochemical reactions and nutrient levels, with corresponding variations in the d15N and d13C of biota. For example, small changes in water level may change the balance of photosynthesis, bacterial respiration, and atmospheric exchange reactions that control the d13C of DIC. Such changes will probably also affect the d15N of dissolved inorganic N (DIN

  20. Food Web Assembly Rules for Generalized Lotka-Volterra Equations

    DEFF Research Database (Denmark)

    Härter, Jan Olaf Mirko; Mitarai, Namiko; Sneppen, Kim

    2016-01-01

    the lack of niches, corresponding to unpaired species. For the species richness at each trophic level, we derive the food web assembly rules, which specify sustainable combinations. In neighboring levels, these rules allow the higher level to avert competitive exclusion at the lower, thereby incorporating...

  1. Food web structure in exotic and native mangroves: A Hawaii-Puerto Rico comparison

    Science.gov (United States)

    Demopoulos, A.W.J.; Fry, B.; Smith, C.R.

    2007-01-01

    Plant invasions can fundamentally alter detrital inputs and the structure of detritus-based food webs. We examined the detrital pathways in mangrove food webs in native (Puerto Rican) and introduced (Hawaiian) Rhizophora mangle forests using a dual isotope approach and a mixing model. Based on trophic-level fractionation of 0-1??? for ?? 13C and 2-3??? for ?? 15N, among the invertebrates, only nematodes, oligochaetes, and nereid polychaetes from native mangroves exhibited stable isotopes consistent with a mangrove-derived diet. Certain fauna, in particular tubificid oligochaetes, had ?? 13C values consistent with the consumption of mangrove leaves, but they were depleted in 15N, suggesting their primary nitrogen source was low in 15N, and was possibly N 2-fixing bacteria. In introduced mangroves, all feeding groups appeared to rely heavily on non-mangrove sources, especially phytoplankton inputs. Mixing model results and discriminant analysis showed clear separation of introduced and native mangrove sites based on differential food source utilization within feeding groups, with stronger and more diverse use of benthic foods observed in native forests. Observed differences between native and invasive mangrove food webs may be due to Hawaiian detritivores being poorly adapted to utilizing the tannin-rich, nitrogen-poor mangrove detritus. In addition, differential utilization of mangrove detritus between native and introduced mangroves may be a consequence of forest age. We postulate that increasing mangrove forest age may promote diversification of bacterial food webs important in N and S cycling. Our results also suggest a potentially important role for sulfur bacteria in supporting the most abundant infaunal consumers, nematodes, in the most mature systems. ?? 2007 Springer-Verlag.

  2. FDA Peanut-Containing Product Recall

    Data.gov (United States)

    U.S. Department of Health & Human Services — The FDA Peanut-Containing Product Recall widget allows you to browse the Food and Drug Administration (FDA) database of peanut butter and peanut-containing products...

  3. Organochlorine pollution in tropical rivers (Guadeloupe): Role of ecological factors in food web bioaccumulation

    Energy Technology Data Exchange (ETDEWEB)

    Coat, Sophie, E-mail: coatsophie@gmail.com [EA 926 DYNECAR, Laboratoire de Biologie Marine, UFR Sciences, Universite des Antilles et de la Guyane, BP592, 97159 Pointe-a-Pitre Cedex (France); Monti, Dominique, E-mail: dominique.monti@univ-ag.fr [EA 926 DYNECAR, Laboratoire de Biologie Marine, UFR Sciences, Universite des Antilles et de la Guyane, BP592, 97159 Pointe-a-Pitre Cedex (France); Legendre, Pierre, E-mail: pierre.legendre@umontreal.ca [Departement de Sciences Biologique, Universite de Montreal, C.P. 6128, succursale A, Montreal, Quebec H3C 3J7 (Canada); Bouchon, Claude, E-mail: claude.bouchon@univ-ag.fr [EA 926 DYNECAR, Laboratoire de Biologie Marine, UFR Sciences, Universite des Antilles et de la Guyane, BP592, 97159 Pointe-a-Pitre Cedex (France); Massat, Felix, E-mail: fmassat@ladrome.fr [LDA26, laboratoire Departemental d' Analyses de la Drome, 27 avenue Lautagne, 26000 Valence (France); Lepoint, Gilles, E-mail: g.lepoint@ulg.ac.be [MARE Centre, Laboratoire d' Oceanologie, Universite de Liege, Bat. B6, 4000 Sart Tilman, Belgique (Belgium)

    2011-06-15

    Concentrations of organochlorine pesticides and stable isotope ratios of nitrogen and carbon were measured in a tropical freshwater ecosystem to evaluate the contamination level of biota and examine the bioaccumulation patterns of pollutants through the food web. Chemical analyses showed a general and heavy contamination of the entire food web. They revealed the strong accumulation of pollutants by juveniles of diadromous fishes and shrimps, as they re-enter the river. The role of ecological factors in the bioaccumulation of pesticides was evaluated. Whereas the most persistent pollutants (chlordecone and monohydro-chlordecone) were related to the organisms diet and habitat, bioaccumulation of {beta}-HCH was only influenced by animal lipid content. The biomagnification potential of chlordecone through the food chain has been demonstrated. It highlighted the importance of trophic transfer in this compound bioaccumulation process. In contrast, bioconcentration by passive diffusion from water seemed to be the main exposure route of biota to {beta}-HCH. - Highlights: > We measured OC pesticides and stable isotope ratios in a tropical stream. > Results showed a strong and ubiquitous contamination of the entire food web. > Diadromous juveniles strongly accumulated pollutants when they re-enter the river. > The most persistent pollutant (chlordecone) was related to species diet and habitat. > {beta}-HCH was only influenced by animal lipid content. - This paper determines the bioaccumulation and transfer processes of organochlorine pesticides within the stream food web in Guadeloupe (Caribbean).

  4. Short-term effects of different genetically modified maize varieties on arthropod food web properties: an experimental field assessment.

    Science.gov (United States)

    Szénási, Ágnes; Pálinkás, Zoltán; Zalai, Mihály; Schmitz, Oswald J; Balog, Adalbert

    2014-06-17

    There is concern that genetically modified (GM) plants may have adverse affects on the arthropod biodiversity comprising agricultural landscapes. The present study report on a two year field experimental test of whether four different genotypic lines, some are novel with no previous field tests, of GM maize hybrids alter the structure of arthropod food webs that they harbour, relative to non-GM maize (control) that is widely used in agriculture. The different GM genotypes produced either Bt toxins, conferred glyphosate tolerance or a combination of the two traits. Quantitative food web analysis, based on short-term assessment assigning a total of 243,896 arthropod individuals collected from the treatments to their positions in food webs, revealed that complex and stable food webs persisted in each maize treatment. Moreover, food web structure remained relatively unchanged by the GM-genotype. The results suggest that at least in short-term period these particular GM maize genotypes will not have adverse effects on arthropod biota of agricultural landscapes.

  5. Spatial variations in food web structures with alternative stable states: evidence from stable isotope analysis in a large eutrophic lake

    Science.gov (United States)

    Li, Yunkai; Zhang, Yuying; Xu, Jun; Zhang, Shuo

    2018-03-01

    Food web structures are well known to vary widely among ecosystems. Moreover, many food web studies of lakes have generally attempted to characterize the overall food web structure and have largely ignored internal spatial and environmental variations. In this study, we hypothesize that there is a high degree of spatial heterogeneity within an ecosystem and such heterogeneity may lead to strong variations in environmental conditions and resource availability, in turn resulting in different trophic pathways. Stable carbon and nitrogen isotopes were employed for the whole food web to describe the structure of the food web in different sub-basins within Taihu Lake. This lake is a large eutrophic freshwater lake that has been intensively managed and highly influenced by human activities for more than 50 years. The results show significant isotopic differences between basins with different environmental characteristics. Such differences likely result from isotopic baseline differences combining with a shift in food web structure. Both are related to local spatial heterogeneity in nutrient loading in waters. Such variation should be explicitly considered in future food web studies and ecosystem-based management in this lake ecosystem.

  6. Spatial variations in food web structures with alternative stable states: evidence from stable isotope analysis in a large eutrophic lake

    Science.gov (United States)

    Li, Yunkai; Zhang, Yuying; Xu, Jun; Zhang, Shuo

    2017-05-01

    Food web structures are well known to vary widely among ecosystems. Moreover, many food web studies of lakes have generally attempted to characterize the overall food web structure and have largely ignored internal spatial and environmental variations. In this study, we hypothesize that there is a high degree of spatial heterogeneity within an ecosystem and such heterogeneity may lead to strong variations in environmental conditions and resource availability, in turn resulting in different trophic pathways. Stable carbon and nitrogen isotopes were employed for the whole food web to describe the structure of the food web in different sub-basins within Taihu Lake. This lake is a large eutrophic freshwater lake that has been intensively managed and highly influenced by human activities for more than 50 years. The results show significant isotopic differences between basins with different environmental characteristics. Such differences likely result from isotopic baseline differences combining with a shift in food web structure. Both are related to local spatial heterogeneity in nutrient loading in waters. Such variation should be explicitly considered in future food web studies and ecosystem-based management in this lake ecosystem.

  7. Prey vulnerability limits top-down control and alters reciprocal feedbacks in a subsidized model food web.

    Directory of Open Access Journals (Sweden)

    William I Atlas

    Full Text Available Resource subsidies increase the productivity of recipient food webs and can affect ecosystem dynamics. Subsidies of prey often support elevated predator biomass which may intensify top-down control and reduce the flow of reciprocal subsidies into adjacent ecosystems. However, top-down control in subsidized food webs may be limited if primary consumers posses morphological or behavioral traits that limit vulnerability to predation. In forested streams, terrestrial prey support high predator biomass creating the potential for strong top-down control, however armored primary consumers often dominate the invertebrate assemblage. Using empirically based simulation models, we tested the response of stream food webs to variations in subsidy magnitude, prey vulnerability, and the presence of two top predators. While terrestrial prey inputs increased predator biomass (+12%, the presence of armored primary consumers inhibited top-down control, and diverted most aquatic energy (∼75% into the riparian forest through aquatic insect emergence. Food webs without armored invertebrates experienced strong trophic cascades, resulting in higher algal (∼50% and detrital (∼1600% biomass, and reduced insect emergence (-90%. These results suggest prey vulnerability can mediate food web responses to subsidies, and that top-down control can be arrested even when predator-invulnerable consumers are uncommon (20% regardless of the level of subsidy.

  8. A Mobile Phone Based Method to Assess Energy and Food Intake in Young Children: A Validation Study against the Doubly Labelled Water Method and 24 h Dietary Recalls

    Directory of Open Access Journals (Sweden)

    Christine Delisle Nyström

    2016-01-01

    Full Text Available Mobile phones are becoming important instruments for assessing diet and energy intake. We developed the Tool for Energy Balance in Children (TECH, which uses a mobile phone to assess energy and food intake in pre-school children. The aims of this study were: (a to compare energy intake (EI using TECH with total energy expenditure (TEE measured via doubly labelled water (DLW; and (b to compare intakes of fruits, vegetables, fruit juice, sweetened beverages, candy, ice cream, and bakery products using TECH with intakes acquired by 24 h dietary recalls. Participants were 39 healthy, Swedish children (5.5 ± 0.5 years within the ongoing Mobile-based Intervention Intended to Stop Obesity in Preschoolers (MINISTOP obesity prevention trial. Energy and food intakes were assessed during four days using TECH and 24 h telephone dietary recalls. Mean EI (TECH was not statistically different from TEE (DLW (5820 ± 820 kJ/24 h and 6040 ± 680kJ/24 h, respectively. No significant differences in the average food intakes using TECH and 24 h dietary recalls were found. All food intakes were correlated between TECH and the 24 h dietary recalls (ρ = 0.665–0.896, p < 0.001. In conclusion, TECH accurately estimated the average intakes of energy and selected foods and thus has the potential to be a useful tool for dietary studies in pre-school children, for example obesity prevention trials.

  9. Isotopic evidence for the spatial heterogeneity of the planktonic food webs in the transition zone between river and lake ecosystems

    Directory of Open Access Journals (Sweden)

    Hideyuki Doi

    2013-12-01

    Full Text Available Resources and organisms in food webs are distributed patchily. The spatial structure of food webs is important and critical to understanding their overall structure. However, there is little available information about the small-scale spatial structure of food webs. We investigated the spatial structure of food webs in a lake ecosystem at the littoral transition zone between an inflowing river and a lake. We measured the carbon isotope ratios of zooplankton and particulate organic matter (POM; predominantly phytoplankton in the littoral zone of a saline lake. Parallel changes in the δ 13C values of zooplankton and their respective POMs indicated that there is spatial heterogeneity of the food web in this study area. Lake ecosystems are usually classified at the landscape level as either pelagic or littoral habitats. However, we showed small-scale spatial heterogeneity among planktonic food webs along an environmental gradient. Stable isotope data is useful for detecting spatial heterogeneity of habitats, populations, communities, and ecosystems.

  10. Simple rules describe bottom-up and top-down control in food webs with alternative energy pathways.

    Science.gov (United States)

    Wollrab, Sabine; Diehl, Sebastian; De Roos, André M

    2012-09-01

    Many human influences on the world's ecosystems have their largest direct impacts at either the top or the bottom of the food web. To predict their ecosystem-wide consequences we must understand how these impacts propagate. A long-standing, but so far elusive, problem in this endeavour is how to reduce food web complexity to a mathematically tractable, but empirically relevant system. Simplification to main energy channels linking primary producers to top consumers has been recently advocated. Following this approach, we propose a general framework for the analysis of bottom-up and top-down forcing of ecosystems by reducing food webs to two energy pathways originating from a limiting resource shared by competing guilds of primary producers (e.g. edible vs. defended plants). Exploring dynamical models of such webs we find that their equilibrium responses to nutrient enrichment and top consumer harvesting are determined by only two easily measurable topological properties: the lengths of the component food chains (odd-odd, odd-even, or even-even) and presence vs. absence of a generalist top consumer reconnecting the two pathways (yielding looped vs. branched webs). Many results generalise to other looped or branched web structures and the model can be easily adapted to include a detrital pathway. © 2012 Blackwell Publishing Ltd/CNRS.

  11. Plankton food-web functioning in anthropogenically impacted coastal waters (SW Mediterranean Sea): An ecological network analysis

    Science.gov (United States)

    Meddeb, Marouan; Grami, Boutheïna; Chaalali, Aurélie; Haraldsson, Matilda; Niquil, Nathalie; Pringault, Olivier; Sakka Hlaili, Asma

    2018-03-01

    The study is the first attempt to (i) model spring food webs in three SW Mediterranean ecosystems which are under different anthropogenic pressures and (ii) to project the consequence of this stress on their function. Linear inverse models were built using the Monte Carlo method coupled with Markov Chains to characterize the food-web status of the Lagoon, the Channel (inshore waters under high eutrophication and chemical contamination) and the Bay of Bizerte (offshore waters under less anthropogenic pressure). Ecological network analysis was used for the description of structural and functional properties of each food web and for inter-ecosystem comparisons. Our results showed that more carbon was produced by phytoplankton in the inshore waters (966-1234 mg C m-2 d-1) compared to the Bay (727 mg C m-2 d-1). The total ecosystem carbon inputs into the three food webs was supported by high primary production, which was mainly due to >10 μm algae. However, the three carbon pathways were characterized by low detritivory and a high herbivory which was mainly assigned to protozooplankton. This latter was efficient in channelling biogenic carbon. In the Lagoon and the Channel, foods webs acted almost as a multivorous structure with a tendency towards herbivorous one, whereas in the Bay the herbivorous pathway was more dominant. Ecological indices revealed that the Lagoon and the Channel food webs/systems had high total system throughput and thus were more active than the Bay. The Bay food web, which had a high relative ascendency value, was more organized and specialized. This inter-ecosystem difference could be due to the varying levels of anthropogenic impact among sites. Indeed, the low value of Finn's cycling index indicated that the three systems are disturbed, but the Lagoon and the Channel, with low average path lengths, appeared to be more stressed, as both sites have undergone higher chemical pollution and nutrient loading. This study shows that ecosystem models

  12. Food-web structure and ecosystem services: insights from the Serengeti.

    Science.gov (United States)

    Dobson, Andy

    2009-06-27

    The central organizing theme of this paper is to discuss the dynamics of the Serengeti grassland ecosystem from the perspective of recent developments in food-web theory. The seasonal rainfall patterns that characterize the East African climate create an annually oscillating, large-scale, spatial mosaic of feeding opportunities for the larger ungulates in the Serengeti; this in turn creates a significant annual variation in the food available for their predators. At a smaller spatial scale, periodic fires during the dry season create patches of highly nutritious grazing that are eaten in preference to the surrounding older patches of less palatable vegetation. The species interactions between herbivores and plants, and carnivores and herbivores, are hierarchically nested in the Serengeti food web, with the largest bodied consumers on each trophic level having the broadest diets that include species from a large variety of different habitats in the ecosystem. The different major habitats of the Serengeti are also used in a nested fashion; the highly nutritious forage of the short grass plains is available only to the larger migratory species for a few months each year. The longer grass areas, the woodlands and kopjes (large partially wooded rocky islands in the surrounding mosaic of grassland) contain species that are resident throughout the year; these species often have smaller body size and more specialized diets than the migratory species. Only the larger herbivores and carnivores obtain their nutrition from all the different major habitat types in the ecosystem. The net effect of this is to create a nested hierarchy of subchains of energy flow within the larger Serengeti food web; these flows are seasonally forced by rainfall and operate at different rates in different major branches of the web. The nested structure that couples sequential trophic levels together interacts with annual seasonal variation in the fast and slow chains of nutrient flow in a way that

  13. Food-web complexity across hydrothermal vents on the Azores triple junction

    Science.gov (United States)

    Portail, Marie; Brandily, Christophe; Cathalot, Cécile; Colaço, Ana; Gélinas, Yves; Husson, Bérengère; Sarradin, Pierre-Marie; Sarrazin, Jozée

    2018-01-01

    The assessment and comparison of food webs across various hydrothermal vent sites can enhance our understanding of ecological processes involved in the structure and function of biodiversity. The Menez Gwen, Lucky Strike and Rainbow vent fields are located on the Azores triple junction of the Mid-Atlantic Ridge. These fields have distinct depths (from 850 to 2320 m) and geological contexts (basaltic and ultramafic), but share similar faunal assemblages defined by the presence of foundation species that include Bathymodiolus azoricus, alvinocarid shrimp and gastropods. We compared the food webs of 13 faunal assemblages at these three sites using carbon and nitrogen stable isotope analyses (SIA). Results showed that photosynthesis-derived organic matter is a negligible basal source for vent food webs, at all depths. The contribution of methanotrophy versus autotrophy based on Calvin-Benson-Bassham (CBB) or reductive tricarboxylic acid (rTCA) cycles varied between and within vent fields according to the concentrations of reduced compounds (e.g. CH4, H2S). Species that were common to vent fields showed high trophic flexibility, suggesting weak trophic links to the metabolism of chemosynthetic primary producers. At the community level, a comparison of SIA-derived metrics between mussel assemblages from two vent fields (Menez Gwen & Lucky Strike) showed that the functional structure of food webs was highly similar in terms of basal niche diversification, functional specialization and redundancy. Coupling SIA to functional trait approaches included more variability within the analyses, but the functional structures were still highly comparable. These results suggest that despite variable environmental conditions (physico-chemical factors and basal sources) and faunal community structure, functional complexity remained relatively constant among mussel assemblages. This functional similarity may be favoured by the propensity of species to adapt to fluid variations and

  14. Bioaccumulation of 137Cs in pelagic food webs in the Norwegian and Barents Seas

    International Nuclear Information System (INIS)

    Heldal, Hilde Elise; Foeyn, Lars; Varskog, Per

    2003-01-01

    Knowledge and documentation of the levels of radioactive contamination in fish stocks important to Norwegian fisheries is of major importance to Norwegian consumers and fish export industry. In the present study, the bioaccumulation of caesium-137 ( 137 Cs) has been investigated in marine food webs in the Barents and Norwegian Seas. The contents of 137 Cs in the different organisms were generally low ( -1 wet weight), but a marked bioaccumulation was apparent: The concentration of 137 Cs was about 10-fold higher in the harbour porpoise Phocoena phocoena, representing the upper level of the food web, than in the amphipod Themisto sp., representing the lower level of the food web. The Concentration Factors (CF=Bq kg -1 wet weight/Bq l -1 seawater) increased from 10±3 for a mixed sample of krill and amphipods to 165±5 for harbour porpoises

  15. Electronic 12-Hour Dietary Recall (e-12HR): Comparison of a Mobile Phone App for Dietary Intake Assessment With a Food Frequency Questionnaire and Four Dietary Records.

    Science.gov (United States)

    Béjar, Luis María; Reyes, Óscar Adrián; García-Perea, María Dolores

    2018-06-15

    One of the greatest challenges in nutritional epidemiology is improving upon traditional self-reporting methods for the assessment of habitual dietary intake. The aim of this study was to evaluate the relative validity of a new method known as the current-day dietary recall (or current-day recall), based on a smartphone app called 12-hour dietary recall, for determining the habitual intake of a series of key food and drink groups using a food frequency questionnaire (FFQ) and four dietary records as reference methods. University students over the age of 18 years recorded their consumption of certain groups of food and drink using 12-hour dietary recall for 28 consecutive days. During this 28-day period, they also completed four dietary records on randomly selected days. Once the monitoring period was over, subjects then completed an FFQ. The two methods were compared using the Spearman correlation coefficient (SCC), a cross-classification analysis, and weighted kappa. A total of 87 participants completed the study (64% women, 56/87; 36% men, 31/87). For e-12HR versus FFQ, for all food and drink groups, the average SCC was 0.70. Cross-classification analysis revealed that the average percentage of individuals classified in the exact agreement category was 51.5%; exact agreement + adjacent was 91.8%, and no participant (0%) was classified in the extreme disagreement category. The average weighted kappa was 0.51. For e-12HR versus the four dietary records, for all food and drink groups, the average SCC was 0.63. Cross-classification analysis revealed that the average percentage of individuals classified in the exact agreement category was 47.1%; exact agreement + adjacent was 89.2%; and no participant (0%) was classified in the extreme disagreement category. The average weighted kappa was 0.47. Current-day recall, based on the 12-hour dietary recall app, was found to be in good agreement with the two reference methods (FFQ & four dietary records), demonstrating its

  16. Highly resolved early Eocene food webs show development of modern trophic structure after the end-Cretaceous extinction.

    Science.gov (United States)

    Dunne, Jennifer A; Labandeira, Conrad C; Williams, Richard J

    2014-05-07

    Generalities of food web structure have been identified for extant ecosystems. However, the trophic organization of ancient ecosystems is unresolved, as prior studies of fossil webs have been limited by low-resolution, high-uncertainty data. We compiled highly resolved, well-documented feeding interaction data for 700 taxa from the 48 million-year-old latest early Eocene Messel Shale, which contains a species assemblage that developed after an interval of protracted environmental and biotal change during and following the end-Cretaceous extinction. We compared the network structure of Messel lake and forest food webs to extant webs using analyses that account for scale dependence of structure with diversity and complexity. The Messel lake web, with 94 taxa, displays unambiguous similarities in structure to extant webs. While the Messel forest web, with 630 taxa, displays differences compared to extant webs, they appear to result from high diversity and resolution of insect-plant interactions, rather than substantive differences in structure. The evidence presented here suggests that modern trophic organization developed along with the modern Messel biota during an 18 Myr interval of dramatic post-extinction change. Our study also has methodological implications, as the Messel forest web analysis highlights limitations of current food web data and models.

  17. Phylogenetic composition of host plant communities drives plant-herbivore food web structure.

    Science.gov (United States)

    Volf, Martin; Pyszko, Petr; Abe, Tomokazu; Libra, Martin; Kotásková, Nela; Šigut, Martin; Kumar, Rajesh; Kaman, Ondřej; Butterill, Philip T; Šipoš, Jan; Abe, Haruka; Fukushima, Hiroaki; Drozd, Pavel; Kamata, Naoto; Murakami, Masashi; Novotny, Vojtech

    2017-05-01

    Insects tend to feed on related hosts. The phylogenetic composition of host plant communities thus plays a prominent role in determining insect specialization, food web structure, and diversity. Previous studies showed a high preference of insect herbivores for congeneric and confamilial hosts suggesting that some levels of host plant relationships may play more prominent role that others. We aim to quantify the effects of host phylogeny on the structure of quantitative plant-herbivore food webs. Further, we identify specific patterns in three insect guilds with different life histories and discuss the role of host plant phylogeny in maintaining their diversity. We studied herbivore assemblages in three temperate forests in Japan and the Czech Republic. Sampling from a canopy crane, a cherry picker and felled trees allowed a complete census of plant-herbivore interactions within three 0·1 ha plots for leaf chewing larvae, miners, and gallers. We analyzed the effects of host phylogeny by comparing the observed food webs with randomized models of host selection. Larval leaf chewers exhibited high generality at all three sites, whereas gallers and miners were almost exclusively monophagous. Leaf chewer generality dropped rapidly when older host lineages (5-80 myr) were collated into a single lineage but only decreased slightly when the most closely related congeneric hosts were collated. This shows that leaf chewer generality has been maintained by feeding on confamilial hosts while only a few herbivores were shared between more distant plant lineages and, surprisingly, between some congeneric hosts. In contrast, miner and galler generality was maintained mainly by the terminal nodes of the host phylogeny and dropped immediately after collating congeneric hosts into single lineages. We show that not all levels of host plant phylogeny are equal in their effect on structuring plant-herbivore food webs. In the case of generalist guilds, it is the phylogeny of deeper

  18. Stability lies in flowers: Plant diversification mediating shifts in arthropod food webs.

    Directory of Open Access Journals (Sweden)

    Marcelo Mendes Haro

    Full Text Available Arthropod community composition in agricultural landscapes is dependent on habitat characteristics, such as plant composition, landscape homogeneity and the presence of key resources, which are usually absent in monocultures. Manipulating agroecosystems through the insertion of in-field floral resources is a useful technique to reduce the deleterious effects of habitat simplification. Food web analysis can clarify how the community reacts to the presence of floral resources which favour ecosystem services such as biological control of pest species. Here, we reported quantitative and qualitative alterations in arthropod food web complexity due to the presence of floral resources from the Mexican marigold (Tagetes erecta L. in a field scale lettuce community network. The presence of marigold flowers in the field successfully increased richness, body size, and the numerical and biomass abundance of natural enemies in the lettuce arthropod community, which affected the number of links, vulnerability, generality, omnivory rate and food chain length in the community, which are key factors for the stability of relationships between species. Our results reinforce the notion that diversification through insertion of floral resources may assist in preventing pest outbreaks in agroecosystems. This community approach to arthropod interactions in agricultural landscapes can be used in the future to predict the effect of different management practices in the food web to contribute with a more sustainable management of arthropod pest species.

  19. A food web modeling analysis of a Midwestern, USA eutrophic lake dominated by non-native Common Carp and Zebra Mussels

    Science.gov (United States)

    Colvin, Michael E.; Pierce, Clay; Stewart, Timothy W.

    2015-01-01

    Food web modeling is recognized as fundamental to understanding the complexities of aquatic systems. Ecopath is the most common mass-balance model used to represent food webs and quantify trophic interactions among groups. We constructed annual Ecopath models for four consecutive years during the first half-decade of a zebra mussel invasion in shallow, eutrophic Clear Lake, Iowa, USA, to evaluate changes in relative biomass and total system consumption among food web groups, evaluate food web impacts of non-native common carp and zebra mussels on food web groups, and to interpret food web impacts in light of on-going lake restoration. Total living biomass increased each year of the study; the majority of the increase due to a doubling in planktonic blue green algae, but several other taxa also increased including a more than two-order of magnitude increase in zebra mussels. Common carp accounted for the largest percentage of total fish biomass throughout the study even with on-going harvest. Chironomids, common carp, and zebra mussels were the top-three ranking consumer groups. Non-native common carp and zebra mussels accounted for an average of 42% of the total system consumption. Despite the relatively high biomass densities of common carp and zebra mussel, food web impacts was minimal due to excessive benthic and primary production in this eutrophic system. Consumption occurring via benthic pathways dominated system consumption in Clear Lake throughout our study, supporting the argument that benthic food webs are significant in shallow, eutrophic lake ecosystems and must be considered if ecosystem-level understanding is to be obtained.

  20. Impacts of food web structure and feeding behavior on mercury exposure in Greenland Sharks (Somniosus microcephalus).

    Science.gov (United States)

    McMeans, Bailey C; Arts, Michael T; Fisk, Aaron T

    2015-03-15

    Benthic and pelagic food web components in Cumberland Sound, Canada were explored as sources of total mercury (THg) to Greenland Sharks (Somniosus microcephalus) via both bottom-up food web transfer and top-down shark feeding behavior. Log10THg increased significantly with δ(15)N and trophic position from invertebrates (0.01 ± 0.01 μg · g(-1) [113 ± 1 ng · g(-1)] dw in copepods) to Greenland Sharks (3.54 ± 1.02 μg · g(-1)). The slope of the log10THg vs. δ(15)N linear regression was higher for pelagic compared to benthic food web components (excluding Greenland Sharks, which could not be assigned to either food web), which resulted from THg concentrations being higher at the base of the benthic food web (i.e., in benthic than pelagic primary consumers). However, feeding habitat is unlikely to consistently influence shark THg exposure in Cumberland Sound because THg concentrations did not consistently differ between benthic and pelagic shark prey. Further, size, gender and feeding behavior (inferred from stable isotopes and fatty acids) were unable to significantly explain THg variability among individual Greenland Sharks. Possible reasons for this result include: 1) individual sharks feeding as generalists, 2) high overlap in THg among shark prey, and 3) differences in turnover time between ecological tracers and THg. This first assessment of Greenland Shark THg within an Arctic food web revealed high concentrations consistent with biomagnification, but low ability to explain intra-specific THg variability. Our findings of high THg levels and consumption of multiple prey types, however, suggest that Greenland Sharks acquire THg through a variety of trophic pathways and are a significant contributor to the total biotic THg pool in northern seas. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Food-web stability signals critical transitions in temperate shallow lakes

    NARCIS (Netherlands)

    Kuiper, Jan J.; van Altena, Cassandra; de Ruiter, P.C.; Van Gerven, Luuk P.A.; Janse, Jan H.; Mooij, Wolf M.

    2015-01-01

    A principal aim of ecologists is to identify critical levels of environmental change beyond which ecosystems undergo radical shifts in their functioning. Both food-web theory and alternative stable states theory provide fundamental clues to mechanisms conferring stability to natural systems. Yet, it

  2. Food-web stability signals critical transitions in temperate shallow lakes

    NARCIS (Netherlands)

    Kuiper, J.J.; Altena, Van Cassandra; Ruiter, De P.C.; Gerven, Van L.P.A.; Janse, J.H.; Mooij, W.M.

    2015-01-01

    A principal aim of ecologists is to identify critical levels of environmental change beyond which ecosystems undergo radical shifts in their functioning. Both food-web theory and alternative stable states theory provide fundamental clues to mechanisms conferring stability to natural systems. Yet,

  3. Nitrogen fixation by cyanobacteria stimulates production in Baltic food webs.

    Science.gov (United States)

    Karlson, Agnes M L; Duberg, Jon; Motwani, Nisha H; Hogfors, Hedvig; Klawonn, Isabell; Ploug, Helle; Barthel Svedén, Jennie; Garbaras, Andrius; Sundelin, Brita; Hajdu, Susanna; Larsson, Ulf; Elmgren, Ragnar; Gorokhova, Elena

    2015-06-01

    Filamentous, nitrogen-fixing cyanobacteria form extensive summer blooms in the Baltic Sea. Their ability to fix dissolved N2 allows cyanobacteria to circumvent the general summer nitrogen limitation, while also generating a supply of novel bioavailable nitrogen for the food web. However, the fate of the nitrogen fixed by cyanobacteria remains unresolved, as does its importance for secondary production in the Baltic Sea. Here, we synthesize recent experimental and field studies providing strong empirical evidence that cyanobacterial nitrogen is efficiently assimilated and transferred in Baltic food webs via two major pathways: directly by grazing on fresh or decaying cyanobacteria and indirectly through the uptake by other phytoplankton and microbes of bioavailable nitrogen exuded from cyanobacterial cells. This information is an essential step toward guiding nutrient management to minimize noxious blooms without overly reducing secondary production, and ultimately most probably fish production in the Baltic Sea.

  4. Stable isotope evidence of long-term changes in North Sea food web structure

    DEFF Research Database (Denmark)

    Richardson, Katherine; Christensen, Jens Tang

    2008-01-01

    coast. Porpoises collected after ~1960 had significantly lower d15N than porpoises collected earlier. This change in d15N implies that fundamental changes in food web structure in, or nutrient availability to, the North Sea have taken place over the last ~150 yr and that most of the change occurred over......, been feeding at a lower trophic level than during the preceding century, i.e. animals from lower trophic levels may now be more dominant than they were prior to the middle of the 20th century. There is no a priori reason to suspect that a change in isotope distributions at the base of the food web has...... occurred during this period and we have not been able to find material that would allow us to test the assumption that there has been no temporal development of d15N at the lowest levels of the food web. Thus, we cannot eliminate the possibility that the change in d15N in harbour porpoise skeletons...

  5. Riverine dominance of a nearshore marine demersal food web ...

    African Journals Online (AJOL)

    The aim of this study was to determine (i) the importance of riverine and marine organic matter for the Thukela Bank food web; and (ii) whether there are seasonal changes in the Thukela River stable isotope values, and, if so, whether these are reflected in the isotope values of demersal organisms. Estuarine organic matter ...

  6. Impacts of food web structure and feeding behavior on mercury exposure in Greenland Sharks (Somniosus microcephalus)

    Energy Technology Data Exchange (ETDEWEB)

    McMeans, Bailey C., E-mail: bcmcmeans@gmail.com [Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario N9B 3P4 (Canada); Arts, Michael T. [Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario N9B 3P4 (Canada); National Water Research Institute, Environment Canada, 867 Lakeshore Road, PO Box 5050, Burlington, Ontario L7R 4A6 (Canada); Fisk, Aaron T. [Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario N9B 3P4 (Canada)

    2015-03-15

    Benthic and pelagic food web components in Cumberland Sound, Canada were explored as sources of total mercury (THg) to Greenland Sharks (Somniosus microcephalus) via both bottom-up food web transfer and top-down shark feeding behavior. Log{sub 10}THg increased significantly with δ{sup 15}N and trophic position from invertebrates (0.01 ± 0.01 μg·g{sup −1} [113 ± 1 ng·g{sup −1}] dw in copepods) to Greenland Sharks (3.54 ± 1.02 μg·g{sup −1}). The slope of the log{sub 10}THg vs. δ{sup 15}N linear regression was higher for pelagic compared to benthic food web components (excluding Greenland Sharks, which could not be assigned to either food web), which resulted from THg concentrations being higher at the base of the benthic food web (i.e., in benthic than pelagic primary consumers). However, feeding habitat is unlikely to consistently influence shark THg exposure in Cumberland Sound because THg concentrations did not consistently differ between benthic and pelagic shark prey. Further, size, gender and feeding behavior (inferred from stable isotopes and fatty acids) were unable to significantly explain THg variability among individual Greenland Sharks. Possible reasons for this result include: 1) individual sharks feeding as generalists, 2) high overlap in THg among shark prey, and 3) differences in turnover time between ecological tracers and THg. This first assessment of Greenland Shark THg within an Arctic food web revealed high concentrations consistent with biomagnification, but low ability to explain intra-specific THg variability. Our findings of high THg levels and consumption of multiple prey types, however, suggest that Greenland Sharks acquire THg through a variety of trophic pathways and are a significant contributor to the total biotic THg pool in northern seas. - Highlights: • THg significantly increased with δ{sup 15}N from invertebrates to Greenland Sharks. • THg increased with δ{sup 15}N at a faster rate through the pelagic than

  7. Impacts of food web structure and feeding behavior on mercury exposure in Greenland Sharks (Somniosus microcephalus)

    International Nuclear Information System (INIS)

    McMeans, Bailey C.; Arts, Michael T.; Fisk, Aaron T.

    2015-01-01

    Benthic and pelagic food web components in Cumberland Sound, Canada were explored as sources of total mercury (THg) to Greenland Sharks (Somniosus microcephalus) via both bottom-up food web transfer and top-down shark feeding behavior. Log 10 THg increased significantly with δ 15 N and trophic position from invertebrates (0.01 ± 0.01 μg·g −1 [113 ± 1 ng·g −1 ] dw in copepods) to Greenland Sharks (3.54 ± 1.02 μg·g −1 ). The slope of the log 10 THg vs. δ 15 N linear regression was higher for pelagic compared to benthic food web components (excluding Greenland Sharks, which could not be assigned to either food web), which resulted from THg concentrations being higher at the base of the benthic food web (i.e., in benthic than pelagic primary consumers). However, feeding habitat is unlikely to consistently influence shark THg exposure in Cumberland Sound because THg concentrations did not consistently differ between benthic and pelagic shark prey. Further, size, gender and feeding behavior (inferred from stable isotopes and fatty acids) were unable to significantly explain THg variability among individual Greenland Sharks. Possible reasons for this result include: 1) individual sharks feeding as generalists, 2) high overlap in THg among shark prey, and 3) differences in turnover time between ecological tracers and THg. This first assessment of Greenland Shark THg within an Arctic food web revealed high concentrations consistent with biomagnification, but low ability to explain intra-specific THg variability. Our findings of high THg levels and consumption of multiple prey types, however, suggest that Greenland Sharks acquire THg through a variety of trophic pathways and are a significant contributor to the total biotic THg pool in northern seas. - Highlights: • THg significantly increased with δ 15 N from invertebrates to Greenland Sharks. • THg increased with δ 15 N at a faster rate through the pelagic than benthic food web. • Benthic primary

  8. Structure and functioning of intertidal food webs along an avian flyway: a omparative approach using stable isotopes

    NARCIS (Netherlands)

    Catry, T.; Lourenco, P.M.; Lopes, R.J.; Carneiro, C.; Alves, J.A.; Costa, J.; Rguibi-Idrissi, H.; Bearhop, S.; Piersma, T.; Granadeiro, J.P.

    2016-01-01

    Food webs and trophic dynamics of coastal systems have been the focus of intense research throughout the world, as they prove to be critical in understanding ecosystem processes and functions. However, very few studies have undertaken a quantitative comparison of entire food webs from a key consumer

  9. Parasites reduce food web robustness because they are sensitive to secondary extinction as illustrated by an invasive estuarine snail

    Science.gov (United States)

    Lafferty, Kevin D.; Kuris, Armand M.

    2009-01-01

    A robust food web is one in which few secondary extinctions occur after removing species. We investigated how parasites affected the robustness of the Carpinteria Salt Marsh food web by conducting random species removals and a hypothetical, but plausible, species invasion. Parasites were much more likely than free-living species to suffer secondary extinctions following the removal of a free-living species from the food web. For this reason, the food web was less robust with the inclusion of parasites. Removal of the horn snail, Cerithidea californica, resulted in a disproportionate number of secondary parasite extinctions. The exotic Japanese mud snail, Batillaria attramentaria, is the ecological analogue of the native California horn snail and can completely replace it following invasion. Owing to the similarities between the two snail species, the invasion had no effect on predator–prey interactions. However, because the native snail is host for 17 host-specific parasites, and the invader is host to only one, comparison of a food web that includes parasites showed significant effects of invasion on the native community. The hypothetical invasion also significantly reduced the connectance of the web because the loss of 17 native trematode species eliminated many links.

  10. Visualizing the Food-Web Effects of Fishing for Tunas in the Pacific Ocean

    Directory of Open Access Journals (Sweden)

    Jefferson T. Hinke

    2004-06-01

    Full Text Available We use food-web models to develop visualizations to compare and evaluate the interactions of tuna fisheries with their supporting food webs in the eastern tropical Pacific (ETP and the central north Pacific (CNP Oceans. In the ETP and CNP models, individual fisheries use slightly different food webs that are defined by the assemblage of targeted tuna species. Distinct energy pathways are required to support different tuna species and, consequently, the specific fisheries that target different tuna assemblages. These simulations suggest that catches of tunas, sharks, and billfishes have lowered the biomass of the upper trophic levels in both systems, whereas increases in intermediate and lower trophic level animals have accompanied the decline of top predators. Trade-offs between fishing and predation mortality rates that occur when multiple fisheries interact with their respective food webs may lead to smaller changes in biomass than if only the effect of a single fishery is considered. Historical simulations and hypothetical management scenarios further demonstrate that the effects of longline and purse seine fisheries have been strongest in upper trophic levels, but that lower trophic levels may respond more strongly to purse-seine fisheries. The apex predator guild has responded most strongly to longlining. Simulations of alternative management strategies that attempt to rebuild shark and billfish populations in each ecosystem reveal that (1 changes in longlining more effectively recover top predator populations than do changes in purse seining and (2 restrictions on both shallow-set longline gear and shark finning may do more to recover top predators than do simple reductions in fishing effort.

  11. Interrogating pollution sources in a mangrove food web using multiple stable isotopes.

    Science.gov (United States)

    Souza, Iara da C; Arrivabene, Hiulana P; Craig, Carol-Ann; Midwood, Andrew J; Thornton, Barry; Matsumoto, Silvia T; Elliott, Michael; Wunderlin, Daniel A; Monferrán, Magdalena V; Fernandes, Marisa N

    2018-06-01

    Anthropogenic activities including metal contamination create well-known problems in coastal mangrove ecosystems but understanding and linking specific pollution sources to distinct trophic levels within these environments is challenging. This study evaluated anthropogenic impacts on two contrasting mangrove food webs, by using stable isotopes (δ 13 C, δ 15 N, 87 Sr/ 86 Sr, 206 Pb/ 207 Pb and 208 Pb/ 207 Pb) measured in sediments, mangrove trees (Rhizophora mangle, Laguncularia racemosa, Avicennia schaueriana), plankton, shrimps (Macrobranchium sp.), crabs (Aratus sp.), oysters (Crassostrea rhizophorae) and fish (Centropomus parallelus) from both areas. Strontium and Pb isotopes were also analysed in water and atmospheric particulate matter (PM). δ 15 N indicated that crab, shrimp and oyster are at intermediate levels within the local food web and fish, in this case C. parallelus, was confirmed at the highest trophic level. δ 15 N also indicates different anthropogenic pressures between both estuaries; Vitória Bay, close to intensive human activities, showed higher δ 15 N across the food web, apparently influenced by sewage. The ratio 87 Sr/ 86 Sr showed the primary influence of marine water throughout the entire food web. Pb isotope ratios suggest that PM is primarily influenced by metallurgical activities, with some secondary influence on mangrove plants and crabs sampled in the area adjacent to the smelting works. To our knowledge, this is the first demonstration of the effect of anthropogenic pollution (probable sewage pollution) on the isotopic fingerprint of estuarine-mangrove systems located close to a city compared to less impacted estuarine mangroves. The influence of industrial metallurgical activity detected using Pb isotopic analysis of PM and mangrove plants close to such an impacted area is also notable and illustrates the value of isotopic analysis in tracing the impact and species affected by atmospheric pollution. Copyright © 2018 Elsevier B

  12. Mercury biomagnification in the food web of Lake Tanganyika (Tanzania, East Africa)

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, L. [School of Environmental Studies and Department of Biology, Queen' s University, Kingston, Ontario, K7L-3N6 (Canada)], E-mail: linda.campbell@queensu.ca; Verburg, Piet [National Institute of Water and Atmospheric Research, PO Box 11-115, Hamilton 3251 (New Zealand); Dixon, D.G. [Department of Biology, University of Waterloo, 200 University Avenue, Waterloo (Canada); Hecky, R.E. [Large Lakes Observatory, University of Minnesota, Duluth, 10 University Drive 204 RLBDuluth, MN 55812-2496 (United States)

    2008-09-01

    Lake Tanganyika is a globally important lake with high endemic biodiversity. Millions of people in the lake basin depend on several fish species for consumption. Due to the importance of fish consumption as an exposure route of mercury to humans, we sampled Lake Tanganyika in 2000 to assess total mercury concentrations and biomagnification of total mercury through the food web. Stable nitrogen and carbon isotope analyses of food web structure indicate a complex food web with overlapping omnivory with some specialist fish species. Stable nitrogen isotope analyses further confirm that mercury is biomagnifying through the Tanganyika food web at rates similar to those seen in Lakes Malawi and Victoria, the other two African Great Lakes. Most collected fish species and all invertebrate species had mercury concentrations below 0.2 {mu}g Hg/g wet weight. However, several fish species, Ctenochromis horei (average 0.15 {mu}g/g ww), Neolamprologus boulengeri (0.2 {mu}g/g ww) , Bathybates spp.spp. (0.21 {mu}g/g ww), Mastacembelus cunningtoni (0.22 {mu}g/g ww) and Clarias theodorae (0.22 {mu}g/g ww) approached or slightly exceeded the World Health Organization (WHO)'s recommended guideline of 0.2 {mu}g Hg/g for vulnerable populations with high rates of fish consumption. Two individuals of the piscivorous fish species Lates microlepis (0.54, 0.78 {mu}g/g ww) and a Polypterus congicus (1.3 {mu}g/g ww) exceeded the international marketing limit value of 0.5 {mu}g/g ww. Because C. theodorae and L. microlepis are also important market fish species, there is a need to monitor mercury concentrations in internationally marketed fish from Lake Tanganikya to ensure that those fish do not present a risk to human consumers.

  13. Mercury biomagnification in the food web of Lake Tanganyika (Tanzania, East Africa)

    International Nuclear Information System (INIS)

    Campbell, L.; Verburg, Piet; Dixon, D.G.; Hecky, R.E.

    2008-01-01

    Lake Tanganyika is a globally important lake with high endemic biodiversity. Millions of people in the lake basin depend on several fish species for consumption. Due to the importance of fish consumption as an exposure route of mercury to humans, we sampled Lake Tanganyika in 2000 to assess total mercury concentrations and biomagnification of total mercury through the food web. Stable nitrogen and carbon isotope analyses of food web structure indicate a complex food web with overlapping omnivory with some specialist fish species. Stable nitrogen isotope analyses further confirm that mercury is biomagnifying through the Tanganyika food web at rates similar to those seen in Lakes Malawi and Victoria, the other two African Great Lakes. Most collected fish species and all invertebrate species had mercury concentrations below 0.2 μg Hg/g wet weight. However, several fish species, Ctenochromis horei (average 0.15 μg/g ww), Neolamprologus boulengeri (0.2 μg/g ww) , Bathybates spp.spp. (0.21 μg/g ww), Mastacembelus cunningtoni (0.22 μg/g ww) and Clarias theodorae (0.22 μg/g ww) approached or slightly exceeded the World Health Organization (WHO)'s recommended guideline of 0.2 μg Hg/g for vulnerable populations with high rates of fish consumption. Two individuals of the piscivorous fish species Lates microlepis (0.54, 0.78 μg/g ww) and a Polypterus congicus (1.3 μg/g ww) exceeded the international marketing limit value of 0.5 μg/g ww. Because C. theodorae and L. microlepis are also important market fish species, there is a need to monitor mercury concentrations in internationally marketed fish from Lake Tanganikya to ensure that those fish do not present a risk to human consumers

  14. Investigating Pathways of Nutrient and Energy Flows Through Aquatic Food Webs Using Stable Isotopes of Carbon and Nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Hadwen, W. L.; Bunn, S. E. [Australian Rivers Institute, Griffith School of Environment, Griffith University, Nathan Campus, Brisbane, Queensland (Australia)

    2013-05-15

    Carbon and nitrogen stable isotopes can provide valuable insights into pathways of nutrient and energy flows in aquatic ecosystems. Carbon stable isotopes are principally used to trace pathways of organic matter transfer through aquatic food webs, particularly with regard to identifying the dominant sources of nutrition for aquatic biota. Stable isotopes of carbon have been widely used to answer one of the most pressing questions in aquatic food web ecology - to what degree do in-stream (autochthonous) and riparian (allochthonous) sources of energy fuel riverine food webs? In conjunction with carbon stable isotopes, nitrogen stable isotopes have been used to determine the trophic position of consumers and to identify the number of trophic levels in aquatic food webs. More recently, stable nitrogen isotopes have been recommended as indicators of anthropogenic disturbances. Specifically, agricultural land uses and/or sewage effluent discharge have been shown to significantly increase {delta}{sup 15}N signatures in primary producers and higher order consumers in freshwater, estuarine and marine environments. Together, carbon and nitrogen stable isotopes can be used to examine natural food web functions as well as the degree to which human modifications to catchments and aquatic environments can influence aquatic ecosystem function. (author)

  15. Mangrove clearing impacts on macrofaunal assemblages and benthic food webs in a tropical estuary.

    Science.gov (United States)

    Bernardino, Angelo Fraga; Gomes, Luiz Eduardo de Oliveira; Hadlich, Heliatrice Louise; Andrades, Ryan; Correa, Lucas Barreto

    2018-01-01

    Despite over 21,000ha of mangrove forests being removed per year in Brazil, ecological changes following mangrove deforestation have been overlooked. Here we evaluated changes in benthic macrofaunal assemblages and food-webs at a mangrove removal and natural sites in a tropical estuary in Eastern Brazil. The impacted site had coarser sediment particle sizes suggesting significant changes in sedimentation processes after forest clearing. Spatial differences in macrofaunal abundance, biomass and diversity were not directly associated with the removal of mangrove forests, supporting recolonization of impacted areas by estuarine fauna. However, benthic assemblage composition, infaunal δ 13 C signatures and food-web diversity markedly differed at the impacted site being strongly related to sedimentary changes. The loss of infaunal trophic diversity that followed mangrove removal suggests that large-scale forest clearing may impact estuarine food webs, with potential consequences to nearby coastal ecosystems given the high clearing rate of mangrove forests in Brazil. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Trophic significance of the kelp Laminaria digitata (Lamour.) for the associated food web: a between-sites comparison

    Science.gov (United States)

    Schaal, Gauthier; Riera, Pascal; Leroux, Cédric

    2009-12-01

    This study aimed at establishing the trophic significance of the kelp Laminaria digitata for consumers inhabiting two rocky shores of Northern Brittany (France), displaying contrasted ecological conditions. The general trophic structure did not vary between these two sites, with a wide diversity of filter-feeders and predators, and only 14% of the species sampled belonging to the grazers' trophic group. The diversity of food sources fueling the food web appeared also similar. The food webs comprised four trophic levels and the prevalence of omnivory appeared relatively low compared to previous studies in the same area. Conversely, to the food web structure, which did not differ, the biochemical composition of L. digitata differed between the two sites, and was correlated to a larger diversity of grazers feeding on this kelp in sheltered conditions. This indicated that the spatial variability occurring in the nutritive value of L. digitata is likely to deeply affect the functioning of kelp-associated food webs. The contribution of L. digitata-derived organic matter to the diet of filter-feeders inhabiting these two environments was assessed using the mixing model Isosource, which showed the higher contribution of kelp matter in sheltered conditions. These results highlight the spatial variability that may occur in the functioning of kelp-associated food webs. Moreover, this suggests that hydrodynamics is likely to control the availability of kelp-derived organic matter to local filter-feeders, probably through an increase of detritus export in exposed areas.

  17. Biodiversity and ecosystem functioning in evolving food webs.

    Science.gov (United States)

    Allhoff, K T; Drossel, B

    2016-05-19

    We use computer simulations in order to study the interplay between biodiversity and ecosystem functioning (BEF) during both the formation and the ongoing evolution of large food webs. A species in our model is characterized by its own body mass, its preferred prey body mass and the width of its potential prey body mass spectrum. On an ecological time scale, population dynamics determines which species are viable and which ones go extinct. On an evolutionary time scale, new species emerge as modifications of existing ones. The network structure thus emerges and evolves in a self-organized manner. We analyse the relation between functional diversity and five community level measures of ecosystem functioning. These are the metabolic loss of the predator community, the total biomasses of the basal and the predator community, and the consumption rates on the basal community and within the predator community. Clear BEF relations are observed during the initial build-up of the networks, or when parameters are varied, causing bottom-up or top-down effects. However, ecosystem functioning measures fluctuate only very little during long-term evolution under constant environmental conditions, despite changes in functional diversity. This result supports the hypothesis that trophic cascades are weaker in more complex food webs. © 2016 The Author(s).

  18. Food web assembly at the landscape scale : Using stable isotopes to reveal changes in trophic structure during succession

    NARCIS (Netherlands)

    Schrama, Maarten; Jouta, Jeltje; Berg, Matty P.; Olff, Han

    Food webs are increasingly evaluated at the landscape scale, accounting for spatial interactions involving different nutrient and energy channels. Also, while long viewed as static, food webs are increasingly seen as dynamic entities that assemble during vegetation succession. The next necessary

  19. Biomagnification of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls in a highly contaminated freshwater food web from South China

    International Nuclear Information System (INIS)

    Wu Jiangping; Luo Xiaojun; Zhang Ying; Yu Mei; Chen Shejun; Mai Bixian; Yang Zhongyi

    2009-01-01

    To evaluate the biomagnification extent of polybrominated diphenyls ethers (PBDEs) and polychlorinated biphenyls (PCBs) in a highly contaminated freshwater food web from South China, trophic magnification factors (TMFs) for 18 PBDE congeners and 53 PCB congeners were calculated. The TMF values ranged 0.26-4.47 for PBDEs and 0.75-5.10 for PCBs. Forty-five of 53 PCBs and BDEs 47, 100 and 154 had TMFs greater than one, suggesting their biomagnification in the present food web. The TMFs for PBDEs were generally smaller than those for PCBs with the same degree of halogenation, indicating a lower biomagnification potential for PBDEs compared to PCBs. For PCBs, it followed a parabolic relationship between TMFs and log K OW (octanol-water partition coefficient). However, this relationship was not significant for PBDEs, possibly due to the more complex behaviors of PBDEs in the food web (e.g., metabolism), compared to that of PCBs. - Forty-five of 53 PCBs magnified in the freshwater food web, while only BDEs 47, 100 and 154 significantly magnified in the same food web

  20. Biomagnification of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls in a highly contaminated freshwater food web from South China

    Energy Technology Data Exchange (ETDEWEB)

    Wu Jiangping [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Luo Xiaojun [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China)], E-mail: luoxiaoj@gig.ac.cn; Zhang Ying; Yu Mei [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Chen Shejun; Mai Bixian [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Yang Zhongyi [School of Life Sciences, SunYat-Sen University, Guangzhou 510275 (China)

    2009-03-15

    To evaluate the biomagnification extent of polybrominated diphenyls ethers (PBDEs) and polychlorinated biphenyls (PCBs) in a highly contaminated freshwater food web from South China, trophic magnification factors (TMFs) for 18 PBDE congeners and 53 PCB congeners were calculated. The TMF values ranged 0.26-4.47 for PBDEs and 0.75-5.10 for PCBs. Forty-five of 53 PCBs and BDEs 47, 100 and 154 had TMFs greater than one, suggesting their biomagnification in the present food web. The TMFs for PBDEs were generally smaller than those for PCBs with the same degree of halogenation, indicating a lower biomagnification potential for PBDEs compared to PCBs. For PCBs, it followed a parabolic relationship between TMFs and log K{sub OW} (octanol-water partition coefficient). However, this relationship was not significant for PBDEs, possibly due to the more complex behaviors of PBDEs in the food web (e.g., metabolism), compared to that of PCBs. - Forty-five of 53 PCBs magnified in the freshwater food web, while only BDEs 47, 100 and 154 significantly magnified in the same food web.

  1. PCB Food Web Dynamics Quantify Nutrient and Energy Flow in Aquatic Ecosystems.

    Science.gov (United States)

    McLeod, Anne M; Paterson, Gordon; Drouillard, Ken G; Haffner, G Douglas

    2015-11-03

    Measuring in situ nutrient and energy flows in spatially and temporally complex aquatic ecosystems represents a major ecological challenge. Food web structure, energy and nutrient budgets are difficult to measure, and it is becoming more important to quantify both energy and nutrient flow to determine how food web processes and structure are being modified by multiple stressors. We propose that polychlorinated biphenyl (PCB) congeners represent an ideal tracer to quantify in situ energy and nutrient flow between trophic levels. Here, we demonstrate how an understanding of PCB congener bioaccumulation dynamics provides multiple direct measurements of energy and nutrient flow in aquatic food webs. To demonstrate this novel approach, we quantified nitrogen (N), phosphorus (P) and caloric turnover rates for Lake Huron lake trout, and reveal how these processes are regulated by both growth rate and fish life history. Although minimal nutrient recycling was observed in young growing fish, slow growing, older lake trout (>5 yr) recycled an average of 482 Tonnes·yr(-1) of N, 45 Tonnes·yr(-1) of P and assimilated 22 TJ yr(-1) of energy. Compared to total P loading rates of 590 Tonnes·yr(-1), the recycling of primarily bioavailable nutrients by fish plays an important role regulating the nutrient states of oligotrophic lakes.

  2. Effects of Seasonal and Spatial Differences in Food Webs on Mercury Concentrations in Fish in the Everglades

    Science.gov (United States)

    Kendall, C.; Bemis, B. E.; Wankel, S. D.; Rawlik, P. S.; Lange, T.; Krabbenhoft, D. P.

    2002-05-01

    A clear understanding of the aquatic food web is essential for determining the entry points and subsequent biomagnification pathways of contaminants such as methyl-mercury (MeHg) in the Everglades. Anthropogenic changes in nutrients can significantly affect the entry points of MeHg by changing food web structure from one dominated by algal productivity to one dominated by macrophytes and associated microbial activity. These changes in the base of the food web can also influence the distribution of animals within the ecosystem, and subsequently the bioaccumulation of MeHg up the food chain. As part of several collaborations with local and other federal agencies, more than 7000 Everglades samples were collected in 1995-99, and analysed for d13C and d15N. Many organisms were also analysed for d34S, gut contents, total Hg, and MeHg. Carbon isotopes effectively distinguish between two main types of food webs: ones where algae is the dominant base of the food web, which are characteristic of relatively pristine marsh sites with long hydroperiods, and ones where macrophyte debris appears to be a significant source of nutrients, which are apparently characteristic of shorter hydroperiod sites, and nutrient-impacted marshes and canals. Many organisms show significant (5-12%) spatial and temporal differences in d13C and d15N values across the Everglades. These differences may reflect site and season-specific differences in the relative importance of algae vs. macrophyte debris to the food web. However, there is a lack of evidence that these sites otherwise differ in food chain length (as determined by d15N values). This conclusion is generally supported by gut contents and mercury data. Furthermore, there are no statistically significant differences between the Delta d15N (predator-algae) values at pristine marsh, nutrient-impacted marsh, or canal sites. The main conclusions from this preliminary comparison of gut contents, stable isotope, and Hg data are: (1) there is

  3. Feasibility of repeated 24-h dietary recalls combined with a food-recording booklet, using EPIC-Soft, among preschoolers

    DEFF Research Database (Denmark)

    Trolle, Ellen; Amiano, P.; Ege, Majken

    2011-01-01

    Background/Objectives:This study evaluates the feasibility among preschoolers of the 2 Ã 24-h dietary recalls (24-HDRs) method combined with a food-recording booklet (FRB), using EPIC-Soft pc-program for the 24-HDR (the software developed to conduct 24-HDRs in the European Prospective Investigation...... for a majority of the parents. In future studies, it may be beneficial to develop the FRB more like a structured food record (FR), which might, in principle, change the method to a one-day FR method from more than a 24-HDR method. It is recommended then to further investigate the use of EPIC-Soft as a data...

  4. Reducing methylmercury accumulation in the food webs of San Francisco Bay and its local watersheds

    International Nuclear Information System (INIS)

    Davis, J.A.; Looker, R.E.; Yee, D.; Marvin-Di Pasquale, M.; Grenier, J.L.; Austin, C.M.; McKee, L.J.; Greenfield, B.K.; Brodberg, R.; Blum, J.D.

    2012-01-01

    San Francisco Bay (California, USA) and its local watersheds present an interesting case study in estuarine mercury (Hg) contamination. This review focuses on the most promising avenues for attempting to reduce methylmercury (MeHg) contamination in Bay Area aquatic food webs and identifying the scientific information that is most urgently needed to support these efforts. Concern for human exposure to MeHg in the region has led to advisories for consumption of sport fish. Striped bass from the Bay have the highest average Hg concentration measured for this species in USA estuaries, and this degree of contamination has been constant for the past 40 years. Similarly, largemouth bass in some Bay Area reservoirs have some of the highest Hg concentrations observed in the entire US. Bay Area wildlife, particularly birds, face potential impacts to reproduction based on Hg concentrations in the tissues of several Bay species. Source control of Hg is one of the primary possible approaches for reducing MeHg accumulation in Bay Area aquatic food webs. Recent findings (particularly Hg isotope measurements) indicate that the decades-long residence time of particle-associated Hg in the Bay is sufficient to allow significant conversion of even the insoluble forms of Hg into MeHg. Past inputs have been thoroughly mixed throughout this shallow and dynamic estuary. The large pool of Hg already present in the ecosystem dominates the fraction converted to MeHg and accumulating in the food web. Consequently, decreasing external Hg inputs can be expected to reduce MeHg in the food web, but it will likely take many decades to centuries before those reductions are achieved. Extensive efforts to reduce loads from the largest Hg mining source (the historic New Almaden mining district) are underway. Hg is spread widely across the urban landscape, but there are a number of key sources, source areas, and pathways that provide opportunities to capture larger quantities of Hg and reduce loads

  5. Reducing methylmercury accumulation in the food webs of San Francisco Bay and its local watersheds

    Energy Technology Data Exchange (ETDEWEB)

    Davis, J.A., E-mail: jay@sfei.org [San Francisco Estuary Institute, 4911 Central Avenue, Richmond, CA 94804 (United States); Looker, R.E. [San Francisco Bay Regional Water Quality Control Board, 1515 Clay Street, Suite 1400, Oakland, CA 94612 (United States); Yee, D. [San Francisco Estuary Institute, 4911 Central Avenue, Richmond, CA 94804 (United States); Marvin-Di Pasquale, M. [U.S. Geological Survey, Water Resources Division/MS 480, 345 Middlefield Road, Menlo Park, CA 94025 (United States); Grenier, J.L. [San Francisco Estuary Institute, 4911 Central Avenue, Richmond, CA 94804 (United States); Austin, C.M. [San Francisco Bay Regional Water Quality Control Board, 1515 Clay Street, Suite 1400, Oakland, CA 94612 (United States); McKee, L.J.; Greenfield, B.K. [San Francisco Estuary Institute, 4911 Central Avenue, Richmond, CA 94804 (United States); Brodberg, R. [California Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, 1001 I Street, Sacramento, CA 95812 (United States); Blum, J.D. [Department of Geological Sciences, University of Michigan, 1100 North University Avenue, Ann Arbor, MI 48109 (United States)

    2012-11-15

    San Francisco Bay (California, USA) and its local watersheds present an interesting case study in estuarine mercury (Hg) contamination. This review focuses on the most promising avenues for attempting to reduce methylmercury (MeHg) contamination in Bay Area aquatic food webs and identifying the scientific information that is most urgently needed to support these efforts. Concern for human exposure to MeHg in the region has led to advisories for consumption of sport fish. Striped bass from the Bay have the highest average Hg concentration measured for this species in USA estuaries, and this degree of contamination has been constant for the past 40 years. Similarly, largemouth bass in some Bay Area reservoirs have some of the highest Hg concentrations observed in the entire US. Bay Area wildlife, particularly birds, face potential impacts to reproduction based on Hg concentrations in the tissues of several Bay species. Source control of Hg is one of the primary possible approaches for reducing MeHg accumulation in Bay Area aquatic food webs. Recent findings (particularly Hg isotope measurements) indicate that the decades-long residence time of particle-associated Hg in the Bay is sufficient to allow significant conversion of even the insoluble forms of Hg into MeHg. Past inputs have been thoroughly mixed throughout this shallow and dynamic estuary. The large pool of Hg already present in the ecosystem dominates the fraction converted to MeHg and accumulating in the food web. Consequently, decreasing external Hg inputs can be expected to reduce MeHg in the food web, but it will likely take many decades to centuries before those reductions are achieved. Extensive efforts to reduce loads from the largest Hg mining source (the historic New Almaden mining district) are underway. Hg is spread widely across the urban landscape, but there are a number of key sources, source areas, and pathways that provide opportunities to capture larger quantities of Hg and reduce loads

  6. Carbon dynamics, food web structure and reclamation strategies in Athabasca oil sands wetlands (CFRAW) : overview and progress

    International Nuclear Information System (INIS)

    Ciborowski, J.; Dixon, D.G.; Foote, L.; Liber, K.; Smits, J.E.

    2009-01-01

    Seven oil sand mining partners and 5 university labs have joined forces to study the effects of mine tailings and process waters on development, health and function of wetland communities formed in post-mining landscapes. The collaborative effort, know as the carbon dynamics, food web structure and reclamation strategies in Athabasca oil sands wetlands (CRFAW), aims to identify the materials and strategies most effective and economical in producing a functioning reclamation landscape. This presentation reported on part of the study that tested predictions about how quickly wetlands amended with reclamation materials approach the conditions of reference wetland systems. It provided a conceptual model of carbon pathways and budgets to assess how the allocation of carbon among compartments changes as newly formed wetlands mature in the boreal system. It was assumed that stockpiling constructed wetlands with peat or topsoil would accelerate succession and community development. Although the bitumen and the naphthenic acids found in constructed wetlands are initially toxic, they may serve as an alternate source of carbon once they degrade. This study also assessed the sources, biological uptake, pathways, and movement through the food web of materials used by the biota in constructed wetlands. Additional studies are examining how the productivity of new wetlands is maintained. Net ecosystem productivity is being monitored along with rates of organic carbon accumulation from microbial, algal, and macrophyte production, and influx of outside materials. The rates of leaf litter breakdown and microbial respiration are being compared to determine how constituents speed or slow food web processes of young and older wetlands. Carbon and nitrogen isotope values in food web compartments indicate which sources are incorporated into the food web as wetlands age. The values are used to determine how this influences community development, food web structure and complexity, and the

  7. Network topology: patterns and mechanisms in plant-herbivore and host-parasitoid food webs.

    Science.gov (United States)

    Cagnolo, Luciano; Salvo, Adriana; Valladares, Graciela

    2011-03-01

    1. Biological communities are organized in complex interaction networks such as food webs, which topology appears to be non-random. Gradients, compartments, nested subsets and even combinations of these structures have been shown in bipartite networks. However, in most studies only one pattern is tested against randomness and mechanistic hypotheses are generally lacking. 2. Here we examined the topology of regional, coexisting plant-herbivore and host-parasitoid food webs to discriminate between the mentioned network patterns. We also evaluated the role of species body size, local abundance, regional frequency and phylogeny as determinants of network topology. 3. We found both food webs to be compartmented, with interaction range boundaries imposed by host phylogeny. Species degree within compartments was mostly related to their regional frequency and local abundance. Only one compartment showed an internal nested structure in the distribution of interactions between species, but species position within this compartment was unrelated to species size or abundance. 4. These results suggest that compartmentalization may be more common than previously considered, and that network structure is a result of multiple, hierarchical, non-exclusive processes. © 2010 The Authors. Journal compilation © 2010 British Ecological Society.

  8. Interaction strength combinations and the overfishing of a marine food web

    OpenAIRE

    Bascompte, Jordi; Melián, Carlos J.; Sala, Enric

    2005-01-01

    The stability of ecological communities largely depends on the strength of interactions between predators and their prey. Here we show that these interaction strengths are structured nonran- domly in a large Caribbean marine food web. Specifically, the cooccurrence of strong interactions on two consecutive levels of food chains occurs less frequently than expected by chance. Even when they occur, these strongly interacting chains are accompa- nied by strong omnivory more often than expected ...

  9. Bioaccumulation of per- and polyfluorinated alkyl substances (PFAS) in selected species from the Barents Sea food web

    International Nuclear Information System (INIS)

    Haukas, Marianne; Berger, Urs; Hop, Haakon; Gulliksen, Bjorn; Gabrielsen, Geir W.

    2007-01-01

    The present study reports concentrations and biomagnification potential of per- and polyfluorinated alkyl substances (PFAS) in species from the Barents Sea food web. The examined species included sea ice amphipod (Gammarus wilkitzkii), polar cod (Boreogadus saida), black guillemot (Cepphus grylle) and glaucous gull (Larus hyperboreus). These were analyzed for PFAS, polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs) and polybrominated diphenyl ethers (PBDEs). Perfluorooctane sulfonate (PFOS) was the predominant of the detected PFAS. Trophic levels and food web transfer of PFAS were determined using stable nitrogen isotopes (δ 15 N). No correlation was found between PFOS concentrations and trophic level within species. However, a non-linear relationship was established when the entire food web was analyzed. Biomagnification factors displayed values >1 for perfluorohexane sulfonate (PFHxS), perfluorononanoic acid (PFNA), PFOS and ΣPFAS(7). Multivariate analyses showed that the degree of trophic transfer of PFAS is similar to that of PCB, DDT and PBDE, despite their accumulation through different pathways. - The first comprehensive survey of fluoroorganic contamination in an European Arctic marine food web

  10. Carbon dynamics, food web structure and reclamation strategies in Athabasca oil sands wetlands (CFRAW)

    International Nuclear Information System (INIS)

    Ciborowski, J.J.; Dixon, G.; Foote, L.; Liber, K.; Smits, J.E.

    2007-01-01

    The remediation and ecology of oilsands constructed wetlands was discussed with reference to a project known as the Carbon dynamics, Food web structure and Reclamation strategies in Athabasca oil sands Wetlands (CFRAW). This joint project between 7 mining partners and 5 universities documents how tailings in constructed wetlands modify maturation leading to natural conditions in a reclaimed landscape. Since wetlands are expected to make up 20-50 per cent of the final reclamation landscape of areas surface mined for oil sands in northeastern Alberta, the project focuses on how quickly wetlands amended with reclamation materials approach the conditions seen in reference wetland systems. This study provided a conceptual model of carbon pathways and budgets to evaluate how the allocation of carbon among compartments changes as newly formed wetlands mature in the boreal system. It is likely that succession and community development will accelerate if constructed wetlands are supplemented with stockpiled peat or topsoil. The bitumens and naphthenic acids found in wetlands constructed with mine tailings materials are initially toxic, but may ultimately serve as an alternate source of carbon once they degrade or are metabolized by bacteria. This study evaluated the sources, biological uptake, pathways, and movement through the food web of materials used by the biota in constructed wetlands, with particular reference to how productivity of new wetlands is maintained. Net ecosystem productivity is being monitored along with rates of organic carbon accumulation from microbial, algal, and macrophyte production, and influx of outside materials. The rates of leaf litter breakdown and microbial respiration are also being monitored to determine how constituents speed or slow food web processes of young and older wetlands. Carbon and nitrogen stable isotope measurements indicate which sources are incorporated into the food web as wetlands age, and how this influences community

  11. Parasites Affect Food Web Structure Primarily through Increased Diversity and Complexity

    NARCIS (Netherlands)

    Dunne, J.A.; Lafferty, K.D.; Dobson, A.P.; Hechinger, R.F.; Kuris, A.M.; Martinez, N.D.; McLaughlin, J.P.; Mouritsen, K.N.; Poulin, R.; Reise, K.; Stouffer, D.B.; Thieltges, D.W.; Williams, R.J.; Zander, C.D.

    2013-01-01

    Comparative research on food web structure has revealed generalities in trophic organization, produced simple models, and allowed assessment of robustness to species loss. These studies have mostly focused on free-living species. Recent research has suggested that inclusion of parasites alters

  12. Web-ADARE: A Web-Aided Data Repairing System

    KAUST Repository

    Gu, Binbin

    2017-03-08

    Data repairing aims at discovering and correcting erroneous data in databases. In this paper, we develop Web-ADARE, an end-to-end web-aided data repairing system, to provide a feasible way to involve the vast data sources on the Web in data repairing. Our main attention in developing Web-ADARE is paid on the interaction problem between web-aided repairing and rule-based repairing, in order to minimize the Web consultation cost while reaching predefined quality requirements. The same interaction problem also exists in crowd-based methods but this is not yet formally defined and addressed. We first prove in theory that the optimal interaction scheme is not feasible to be achieved, and then propose an algorithm to identify a scheme for efficient interaction by investigating the inconsistencies and the dependencies between values in the repairing process. Extensive experiments on three data collections demonstrate the high repairing precision and recall of Web-ADARE, and the efficiency of the generated interaction scheme over several baseline ones.

  13. Web-ADARE: A Web-Aided Data Repairing System

    KAUST Repository

    Gu, Binbin; Li, Zhixu; Yang, Qiang; Xie, Qing; Liu, An; Liu, Guanfeng; Zheng, Kai; Zhang, Xiangliang

    2017-01-01

    Data repairing aims at discovering and correcting erroneous data in databases. In this paper, we develop Web-ADARE, an end-to-end web-aided data repairing system, to provide a feasible way to involve the vast data sources on the Web in data repairing. Our main attention in developing Web-ADARE is paid on the interaction problem between web-aided repairing and rule-based repairing, in order to minimize the Web consultation cost while reaching predefined quality requirements. The same interaction problem also exists in crowd-based methods but this is not yet formally defined and addressed. We first prove in theory that the optimal interaction scheme is not feasible to be achieved, and then propose an algorithm to identify a scheme for efficient interaction by investigating the inconsistencies and the dependencies between values in the repairing process. Extensive experiments on three data collections demonstrate the high repairing precision and recall of Web-ADARE, and the efficiency of the generated interaction scheme over several baseline ones.

  14. Nutrition content of food and beverage products on Web sites popular with children.

    Science.gov (United States)

    Lingas, Elena O; Dorfman, Lori; Bukofzer, Eliana

    2009-11-01

    We assessed the nutritional quality of branded food and beverage products advertised on 28 Web sites popular with children. Of the 77 advertised products for which nutritional information was available, 49 met Institute of Medicine criteria for foods to avoid, 23 met criteria for foods to neither avoid nor encourage, and 5 met criteria for foods to encourage. There is a need for further research on the nature and extent of food and beverage advertising online to aid policymakers as they assess the impact of this marketing on children.

  15. Food webs of the Delta, Suisun Bay and Suisun Marsh: an update on current understanding and possibilities for management

    Science.gov (United States)

    Brown, Larry R.; Kimmerer, Wim J.; Conrad, Louise; Lesmeister, Sarah; Mueller-Solger, Anke

    2016-01-01

    This paper reviews and highlights recent research findings on foodweb processes since an earlier review by Kimmerer et al. (2008). We conduct this review within a conceptual framework of the Delta-Suisun food web, which includes both temporal and spatial components. The temporal component is based on knowledge that the landscape has changed markedly from historical conditions. The spatial component of our framework acknowledges that the food web is not spatially static; it varies regionally and across habitat types within regions. The review highlights the idea of a changing baseline with respect to foodweb function. New research also indicates that interactions between habitat-specific food webs vary across the current landscape. For example, based on early work in the South Delta, the food web associated with submerged aquatic vegetation was thought to provide little support to species of concern; however, data from other regions of the estuary suggest that this conceptual model may not apply across the entire region. Habitat restoration has been proposed as a method of re-establishing historic foodweb processes to support species of concern. Benefits are likely for species that directly access such restored habitats, but are less clear for pelagic species. Several topics require attention to further improve the knowledge of food webs needed to support effective management, including: 1) synthesis of factors responsible for low pelagic biomass; 2) monitoring and research on effects of harmful algal blooms; 3) broadening the scope of long-term monitoring; 4) determining benefits of tidal wetland restoration to species of concern, including evaluations of interactions of habitat-specific food webs; and 5) interdisciplinary analysis and synthesis. The only certainty is that food webs will continue to change in response to the changes in the physical environment and new species invasions.

  16. Detritus fuels ecosystem metabolism but not metazoan food webs in San Francisco estuary's freshwater delta

    Science.gov (United States)

    Sobczak, W.V.; Cloern, J.E.; Jassby, A.D.; Cole, B.E.; Schraga, T.S.; Arnsberg, A.

    2005-01-01

    Detritus from terrestrial ecosystems is the major source of organic matter in many streams, rivers, and estuaries, yet the role of detritus in supporting pelagic food webs is debated. We examined the importance of detritus to secondary productivity in the Sacramento and San Joaquin River Delta (California, United States), a large complex of tidal freshwater habitats. The Delta ecosystem has low primary productivity but large detrital inputs, so we hypothesized that detritus is the primary energy source fueling production in pelagic food webs. We assessed the sources, quantity, composition, and bioavailability of organic matter among a diversity of habitats (e.g., marsh sloughs, floodplains, tidal lakes, and deep river channels) over two years to test this hypothesis. Our results support the emerging principle that detritus dominates riverine and estuarine organic matter supply and supports the majority of ecosystem metabolism. Yet in contrast to prevailing ideas, we found that detritus was weakly coupled to the Delta's pelagic food web. Results from independent approaches showed that phytoplankton production was the dominant source of organic matter for the Delta's pelagic food web, even though primary production accounts for a small fraction of the Delta's organic matter supply. If these results are general, they suggest that the value of organic matter to higher trophic levels, including species targeted by programs of ecosystem restoration, is a function of phytoplankton production. ?? 2005 Estuarine Research Federation.

  17. Food web flows through a sub-arctic deep-sea benthic community

    Science.gov (United States)

    Gontikaki, E.; van Oevelen, D.; Soetaert, K.; Witte, U.

    2011-11-01

    The benthic food web of the deep Faroe-Shetland Channel (FSC) was modelled by using the linear inverse modelling methodology. The reconstruction of carbon pathways by inverse analysis was based on benthic oxygen uptake rates, biomass data and transfer of labile carbon through the food web as revealed by a pulse-chase experiment. Carbon deposition was estimated at 2.2 mmol C m -2 d -1. Approximately 69% of the deposited carbon was respired by the benthic community with bacteria being responsible for 70% of the total respiration. The major fraction of the labile detritus flux was recycled within the microbial loop leaving merely 2% of the deposited labile phytodetritus available for metazoan consumption. Bacteria assimilated carbon at high efficiency (0.55) but only 24% of bacterial production was grazed by metazoans; the remaining returned to the dissolved organic matter pool due to viral lysis. Refractory detritus was the basal food resource for nematodes covering ∼99% of their carbon requirements. On the contrary, macrofauna seemed to obtain the major part of their metabolic needs from bacteria (49% of macrofaunal consumption). Labile detritus transfer was well-constrained, based on the data from the pulse-chase experiment, but appeared to be of limited importance to the diet of the examined benthic organisms (preferred prey, in this case, was other macrofaunal animals rather than nematodes. Bacteria and detritus contributed 53% and 12% to the total carbon ingestion of carnivorous polychaetes suggesting a high degree of omnivory among higher consumers in the FSC benthic food web. Overall, this study provided a unique insight into the functioning of a deep-sea benthic community and demonstrated how conventional data can be exploited further when combined with state-of-the-art modelling approaches.

  18. Biomagnification of mercury in selected species from an Arctic marine food web in Svalbard

    International Nuclear Information System (INIS)

    Jaeger, Iris; Hop, Haakon; Gabrielsen, Geir W.

    2009-01-01

    Concentrations and biomagnification of total mercury (TotHg) and methyl mercury (MeHg) were studied in selected species from the pelagic food web in Kongsfjorden, Svalbard. Twelve species of zooplankton, fish and seabirds, were sampled representing a gradient of trophic positions in the Svalbard marine food web. TotHg and MeHg were analysed in liver, muscle and/or whole specimens. The present study is the first to provide MeHg levels in seabirds from the Svalbard area. The relative MeHg levels decreased with increasing levels of TotHg in seabird tissues. Stable isotopes of nitrogen (δ 15 N) were used to determine the trophic levels and the rate of biomagnification of mercury in the food web. A linear relationship between mercury levels and trophic position was found for all seabird species combined and their trophic level, but there was no relationship within species. Biomagnification factors were all > 1 for both TotHg and MeHg, indicating biomagnification from prey to predator. TotHg levels in the different seabirds were similar to levels detected in the Kongsfjorden area in the 1990s.

  19. Aquatic food webs in mangrove and seagrass habitats of Centla Wetland, a Biosphere Reserve in Southeastern Mexico

    Directory of Open Access Journals (Sweden)

    Manuel Mendoza-Carranza

    Full Text Available Mangrove and seagrass habitats are important components of tropical coastal zones worldwide, and are conspicuous habitats of Centla Wetland Biosphere Reserve (CWBR in Tabasco, Mexico. In this study, we examine food webs in mangrove- and seagrass-dominated habitats of CWBR using stable isotope ratios of carbon and nitrogen. Our objective was to identify the importance of carbon derived from mangroves and seagrasses to secondary production of aquatic consumers in this poorly studied conservation area. Carbon and nitrogen isotope ratios of basal sources and aquatic consumers indicated that the species-rich food webs of both habitats are dependent on riparian production sources. The abundant Red mangrove Rhizophora mangle appears to be a primary source of carbon for the mangrove creek food web. Even though dense seagrass beds were ubiquitous, most consumers in the lagoon food web appeared to rely on carbon derived from riparian vegetation (e.g. Phragmites australis. The introduced Amazon sailfin catfish Pterygoplichthys pardalis had isotope signatures overlapping with native species (including high-value fisheries species, suggesting potential competition for resources. Future research should examine the role played by terrestrial insects in linking riparian and aquatic food webs, and impacts of the expanding P. pardalis population on ecosystem function and fisheries in CWBR. Our findings can be used as a baseline to reinforce the conservation and management of this important reserve in the face of diverse external and internal human impacts.

  20. Validation of an Online Food Frequency Questionnaire against Doubly Labelled Water and 24 h Dietary Recalls in Pre-School Children.

    Science.gov (United States)

    Delisle Nyström, Christine; Henriksson, Hanna; Alexandrou, Christina; Bergström, Anna; Bonn, Stephanie; Bälter, Katarina; Löf, Marie

    2017-01-13

    The development of easy-to-use and accurate methods to assess the intake of energy, foods and nutrients in pre-school children is needed. KidMeal-Q is an online food frequency questionnaire developed for the LifeGene prospective cohort study in Sweden. The aims of this study were to compare: (i) energy intake (EI) obtained using KidMeal-Q to total energy expenditure (TEE) measured via doubly labelled water and (ii) the intake of certain foods measured using KidMeal-Q to intakes acquired by means of 24 h dietary recalls in 38 children aged 5.5 years. The mean EI calculated using KidMeal-Q was statistically different ( p food frequency questionnaires. However, its accuracy needs to be improved before it can be used in studies in pre-school children.

  1. Metamorphosis alters contaminants and chemical tracers in insects: implications for food webs.

    Science.gov (United States)

    Kraus, Johanna M; Walters, David M; Wesner, Jeff S; Stricker, Craig A; Schmidt, Travis S; Zuellig, Robert E

    2014-09-16

    Insects are integral to most freshwater and terrestrial food webs, but due to their accumulation of environmental pollutants they are also contaminant vectors that threaten reproduction, development, and survival of consumers. Metamorphosis from larvae to adult can cause large chemical changes in insects, altering contaminant concentrations and fractionation of chemical tracers used to establish contaminant biomagnification in food webs, but no framework exists for predicting and managing these effects. We analyzed data from 39 studies of 68 analytes (stable isotopes and contaminants), and found that metamorphosis effects varied greatly. δ(15)N, widely used to estimate relative trophic position in biomagnification studies, was enriched by ∼ 1‰ during metamorphosis, while δ(13)C used to estimate diet, was similar in larvae and adults. Metals and polycyclic aromatic hydrocarbons (PAHs) were predominantly lost during metamorphosis leading to ∼ 2 to 125-fold higher larval concentrations and higher exposure risks for predators of larvae compared to predators of adults. In contrast, manufactured organic contaminants (such as polychlorinated biphenyls) were retained and concentrated in adults, causing up to ∼ 3-fold higher adult concentrations and higher exposure risks to predators of adult insects. Both food web studies and contaminant management and mitigation strategies need to consider how metamorphosis affects the movement of materials between habitats and ecosystems, with special regard for aquatic-terrestrial linkages.

  2. The soil food web revisited: Diverse and widespread mycophagous soil protists

    NARCIS (Netherlands)

    Geisen, Stefan; Koller, R.; Hünninghaus, M.; Dumack, K.; Urich, T.; Bonkowski, M.

    2016-01-01

    Soil protists are commonly suggested being solely bacterivorous, serving together with bacterivorous nematodes as the main controllers of the bacterial energy channel in soil food webs. In contrast, the fungal energy channel is assumed to be controlled by arthropods and mycophagous nematodes. This

  3. Tracing biogeochemical subsidies from glacier runoff into Alaska's coastal marine food webs

    Science.gov (United States)

    Arimitsu, Mayumi L.; Hobson, Keith A.; Webber, D'Arcy N.; Piatt, John F.; Hood, Eran W.; Fellman, Jason B.

    2018-01-01

    Nearly half of the freshwater discharge into the Gulf of Alaska originates from landscapes draining glacier runoff, but the influence of the influx of riverine organic matter on the trophodynamics of coastal marine food webs is not well understood. We quantified the ecological impact of riverine organic matter subsidies to glacier-marine habitats by developing a multi-trophic level Bayesian three-isotope mixing model. We utilized large gradients in stable (δ13C, δ15N, δ2H) and radiogenic (Δ14C) isotopes that trace riverine and marine organic matter sources as they are passed from lower to higher trophic levels in glacial-marine habitats. We also compared isotope ratios between glacial-marine and more oceanic habitats. Based on isotopic measurements of potential baseline sources, ambient water and tissues of marine consumers, estimates of the riverine organic matter source contribution to upper trophic-level species including fish and seabirds ranged from 12% to 44%. Variability in resource use among similar taxa corresponded to variation in species distribution and life histories. For example, riverine organic matter assimilation by the glacier-nesting seabirds Kittlitz's murrelet (Brachyramphus brevirostris) was greater than that of the forest-nesting marbled murrelet (B. marmoratus). The particulate and dissolved organic carbon in glacial runoff and near surface coastal waters was aged (12100–1500 years BP 14C-age) but dissolved inorganic carbon and biota in coastal waters were young (530 years BP 14C-age to modern). Thus terrestrial-derived subsidies in marine food webs were primarily composed of young organic matter sources released from glacier ecosystems and their surrounding watersheds. Stable isotope compositions also revealed a divergence in food web structure between glacial-marine and oceanic sites. This work demonstrates linkages between terrestrial and marine ecosystems, and facilitates a greater understanding of how climate-driven changes

  4. Mercury bioaccumulation in bats reflects dietary connectivity to aquatic food webs.

    Science.gov (United States)

    Becker, Daniel J; Chumchal, Matthew M; Broders, Hugh G; Korstian, Jennifer M; Clare, Elizabeth L; Rainwater, Thomas R; Platt, Steven G; Simmons, Nancy B; Fenton, M Brock

    2018-02-01

    Mercury (Hg) is a persistent and widespread heavy metal with neurotoxic effects in wildlife. While bioaccumulation of Hg has historically been studied in aquatic food webs, terrestrial consumers can become contaminated with Hg when they feed on aquatic organisms (e.g., emergent aquatic insects, fish, and amphibians). However, the extent to which dietary connectivity to aquatic ecosystems can explain patterns of Hg bioaccumulation in terrestrial consumers has not been well studied. Bats (Order: Chiroptera) can serve as a model system for illuminating the trophic transfer of Hg given their high dietary diversity and foraging links to both aquatic and terrestrial food webs. Here we quantitatively characterize the dietary correlates of long-term exposure to Hg across a diverse local assemblage of bats in Belize and more globally across bat species from around the world with a comparative analysis of hair samples. Our data demonstrate considerable interspecific variation in hair total Hg concentrations in bats that span three orders of magnitude across species, ranging from 0.04 mg/kg in frugivorous bats (Artibeus spp.) to 145.27 mg/kg in the piscivorous Noctilio leporinus. Hg concentrations showed strong phylogenetic signal and were best explained by dietary connectivity of bat species to aquatic food webs. Our results highlight that phylogeny can be predictive of Hg concentrations through similarity in diet and how interspecific variation in feeding strategies influences chronic exposure to Hg and enables movement of contaminants from aquatic to terrestrial ecosystems. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Validation of Web-Based Physical Activity Measurement Systems Using Doubly Labeled Water

    Science.gov (United States)

    Yamaguchi, Yukio; Yamada, Yosuke; Tokushima, Satoru; Hatamoto, Yoichi; Sagayama, Hiroyuki; Kimura, Misaka; Higaki, Yasuki; Tanaka, Hiroaki

    2012-01-01

    Background Online or Web-based measurement systems have been proposed as convenient methods for collecting physical activity data. We developed two Web-based physical activity systems—the 24-hour Physical Activity Record Web (24hPAR WEB) and 7 days Recall Web (7daysRecall WEB). Objective To examine the validity of two Web-based physical activity measurement systems using the doubly labeled water (DLW) method. Methods We assessed the validity of the 24hPAR WEB and 7daysRecall WEB in 20 individuals, aged 25 to 61 years. The order of email distribution and subsequent completion of the two Web-based measurements systems was randomized. Each measurement tool was used for a week. The participants’ activity energy expenditure (AEE) and total energy expenditure (TEE) were assessed over each week using the DLW method and compared with the respective energy expenditures estimated using the Web-based systems. Results The mean AEE was 3.90 (SD 1.43) MJ estimated using the 24hPAR WEB and 3.67 (SD 1.48) MJ measured by the DLW method. The Pearson correlation for AEE between the two methods was r = .679 (P WEB and 3.80 (SD 1.36) MJ by the DLW method. The Pearson correlation for AEE between the two methods was r = .144 (P = .54). The Bland-Altman 95% limits of agreement ranged from –3.83 to 4.81 MJ between the two methods. The Pearson correlation for TEE between the two methods was r = .590 (P = .006). The average input times using terminal devices were 8 minutes and 10 seconds for the 24hPAR WEB and 6 minutes and 38 seconds for the 7daysRecall WEB. Conclusions Both Web-based systems were found to be effective methods for collecting physical activity data and are appropriate for use in epidemiological studies. Because the measurement accuracy of the 24hPAR WEB was moderate to high, it could be suitable for evaluating the effect of interventions on individuals as well as for examining physical activity behavior. PMID:23010345

  6. The Role of Highly Unsaturated Fatty Acids in Aquatic Food Webs

    Science.gov (United States)

    Perhar, G.; Arhonditsis, G. B.

    2009-05-01

    Highly unsaturated fatty acids (HUFAs) are important molecules transferred across the plant-animal interface in aquatic food webs. Defined here as carbon chains of length 18 (carbons) or more, with a double bond in the third (Omega 3) or sixth (Omega 6) bond from the methyl end, HUFAs are formed in primary producers (phytoplankton). With limited abilities to synthesize de novo, consumers and higher trophic organisms are required to obtain their HUFAs primarily from diet. Bioconversion of HUFAs from one form to another is in theory possible, as is synthesis via elongation and the transformation of a saturated to highly saturated fatty acid, but the enzymes required for these processes are absent in most species. HUFAs are hypothesized to be somatic growth limiting compounds for herbivorous zooplankton and have been shown to be critical for juvenile fish growth and wellbeing. Zooplankton tend to vary their fatty acid concentrations, collection strategies and utilization methods based on taxonomy, and various mechanisms have been suggested to account for these differences i.e., seasonal and nervous system hypotheses. Considering also the facts that copepods overwinter in an active state while daphnids overwinter as resting eggs, and that copepods tend to accumulate Docosahexaenoic acid (DHA) through collection and bioconversion, while daphnids focus on Eicosapentaenoic acid (EPA), one can link high DHA concentrations to active overwintering; but both EPA and DHA have similar melting points, putting DHA's cold weather adaptation abilities into question. Another characteristic setting copepods apart from daphnids is nervous system complexity: copepod axons are coated in thick myelin sheaths, permitting rapid neural processing, such as rapid prey attack and intelligent predator avoidance; DHA may be required for the proper functioning of copepod neurons. Recent modeling results have suggested food webs with high quality primary producers (species high in HUFAs, i

  7. The floodplain food web mosaic: a study of its importance to salmon and steelhead with implications for their recovery

    Science.gov (United States)

    Bellmore, J. Ryan; Baxter, Colden V.; Martens, Kyle; Connolly, Patrick J.

    2013-01-01

    Although numerous studies have attempted to place species of interest within the context of food webs, such efforts have generally occurred at small scales or disregard potentially important spatial heterogeneity. If food web approaches are to be employed to manage species, studies are needed that evaluate the multiple habitats and associated webs of interactions in which these species participate. Here, we quantify the food webs that sustain rearing salmon and steelhead within a floodplain landscape of the Methow River, Washington, USA, a location where restoration has been proposed to restore side channels in an attempt to recover anadromous fishes. We combined year-long measures of production, food demand, and diet composition for the fish assemblage with estimates of invertebrate prey productivity to quantify food webs within the main channel and five different, intact, side channels; ranging from channels that remained connected to the main channel at low flow to those reduced to floodplain ponds. Although we found that habitats within the floodplain had similar invertebrate prey production, these habitats hosted different local food webs. In the main channel, 95% of total prey consumption flowed to fishes that are not the target of proposed restoration. These fishes consumed 64% and 47% of the prey resources that were found to be important to fueling chinook and steelhead production in the main channel, respectively. Conversely, in side channels, a greater proportion of prey was consumed by anadromous salmonids. As a result, carrying capacity estimates based on food were 251% higher, on average, for anadromous salmonids in side channels than the main channel. However, salmon and steelhead production was generally well below estimated capacity in both the main and side channels, suggesting these habitats are under-seeded with respect to food, and that much larger populations could be supported. Overall, this study demonstrates that floodplain heterogeneity is

  8. Benthic primary producers are key to sustain the Wadden Sea food web: stable carbon isotope analysis at landscape scale

    NARCIS (Netherlands)

    Christianen, M.J.A.; Middelburg, J.J.; Holthuijsen, S.J.; Jouta, J.; Compton, T.J.; van der Heide, T.; Piersma, T.; Sinninghe Damsté, J.S.; van der Veer, H.W.; Schouten, S.; Olff, H.

    2017-01-01

    Coastal food webs can be supported by local benthic or pelagic primary produc-ers and by the import of organic matter. Distinguishing between these energy sources is essen-tial for our understanding of ecosystem functioning. However, the relative contribution ofthese components to the food web at

  9. Benthic primary producers are key to sustain the Wadden Sea food web : stable carbon isotope analysis at landscape scale

    NARCIS (Netherlands)

    Christianen, M.J.A.; Middelburg, Jack J.|info:eu-repo/dai/nl/079665373; Holthuijsen, S.J.; Jouta, J.; Compton, T.J.; van der Heide, T.; Piersma, T.; Sinninghe Damsté, Jaap S.|info:eu-repo/dai/nl/07401370X; van der Veer, H.W.; Schouten, Stefan|info:eu-repo/dai/nl/137124929; Olff, H.

    Coastal food webs can be supported by local benthic or pelagic primary producers and by the import of organic matter. Distinguishing between these energy sources is essential for our understanding of ecosystem functioning. However, the relative contribution of these components to the food web at the

  10. Benthic primary producers are key to sustain the Wadden Sea food web : Stable carbon isotope analysis at landscape scale

    NARCIS (Netherlands)

    Christianen, M J A; Middelburg, J J; Holthuijsen, S J; Jouta, J; Compton, T J; van der Heide, T; Piersma, T.; Sinninghe Damsté, J S; van der Veer, H W; Schouten, S; Olff, H

    Coastal food webs can be supported by local benthic or pelagic primary producers and by the import of organic matter. Distinguishing between these energy sources is essential for our understanding of ecosystem functioning. However, the relative contribution of these components to the food web at the

  11. The structure of the pelagic food web in relation to water column structure in the Skagerrak

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Kaas, H.; Kruse, B.

    1990-01-01

    by a doming of the pycnocline, with a deep mixed layer along the periphery and a very shallow pycnocline in central parts. Average phytoplankton size increased with the depth of the upper mixed layer, and the central stratified area was characterized by small flagellates while large and chain-forming diatoms...... on particle surface area rather than particle volume or chl a, and showed a distributional pattern that was nearly the inverse of the distribution of copepod activity. That is, peak bacterial growth rates occurred in central, stratified parts and lower rates were found along the margin with a deep mixed layer....... Thus a 'microbial loop' type of food web seemed to be evolving in the central, strongly stratified parts of the Skagerrak, while a shorter 'classical' type of food web appeared to dominate along the margin. The relation between food web structure and vertical mixing processes observed on oceanwide...

  12. Experimentally reducing species abundance indirectly affects food web structure and robustness.

    Science.gov (United States)

    Barbosa, Milton; Fernandes, G Wilson; Lewis, Owen T; Morris, Rebecca J

    2017-03-01

    Studies on the robustness of ecological communities suggest that the loss or reduction in abundance of individual species can lead to secondary and cascading extinctions. However, most such studies have been simulation-based analyses of the effect of primary extinction on food web structure. In a field experiment we tested the direct and indirect effects of reducing the abundance of a common species, focusing on the diverse and self-contained assemblage of arthropods associated with an abundant Brazilian shrub, Baccharis dracunculifolia D.C. (Asteraceae). Over a 5-month period we experimentally reduced the abundance of Baccharopelma dracunculifoliae (Sternorrhyncha: Psyllidae), the commonest galling species associated with B. dracunculifolia, in 15 replicate plots paired with 15 control plots. We investigated direct effects of the manipulation on parasitoids attacking B. dracunculifoliae, as well as indirect effects (mediated via a third species or through the environment) on 10 other galler species and 50 associated parasitoid species. The experimental manipulation significantly increased parasitism on B. dracunculifoliae in the treatment plots, but did not significantly alter either the species richness or abundance of other galler species. Compared to control plots, food webs in manipulated plots had significantly lower values of weighted connectance, interaction evenness and robustness (measured as simulated tolerance to secondary extinction), even when B. dracunculifoliae was excluded from calculations. Parasitoid species were almost entirely specialized to individual galler species, so the observed effects of the manipulation on food web structure could not have propagated via the documented trophic links. Instead, they must have spread either through trophic links not included in the webs (e.g. shared predators) or non-trophically (e.g. through changes in habitat availability). Our results highlight that the inclusion of both trophic and non

  13. Soil food web structure after wood ash application

    DEFF Research Database (Denmark)

    Mortensen, Louise Hindborg; Qin, Jiayi; Cruz-Paredes, Carla

    the consequences of returning wood ash to biofuel producing coniferous forest. We that the change in pH and increased availability of nutrients after ash application to forest floor can facilitate an increase in the bacteria to fungi ratio with possible effects for the soil food by applying ash of different...... concentrations to experimental plots in a coniferous forest the soil will be collected with varying intervals and subsequently analyzed. The food web included several trophic levels; bacteria/fungi, protozoa, nematodes, enchytraeids and microarthropods and arthropods. Results from 2014 indicated that bacteria...... and protozoa were stimulated in the uppermost soil layer (0-3 cm) two months ash application, whereas the enchytraeids seemed to be slightly negatively affected. Generally, nematodes also appeared to be negatively affected, although it differed between feeding groups. On the higher trophic levels, no effect...

  14. Food web architecture and basal resources interact to determine biomass and stoichiometric cascades along a benthic food web.

    Directory of Open Access Journals (Sweden)

    Rafael D Guariento

    Full Text Available Understanding the effects of predators and resources on primary producers has been a major focus of interest in ecology. Within this context, the trophic cascade concept especially concerning the pelagic zone of lakes has been the focus of the majority of these studies. However, littoral food webs could be especially interesting because base trophic levels may be strongly regulated by consumers and prone to be light limited. In this study, the availability of nutrients and light and the presence of an omnivorous fish (Hyphessobrycon bifasciatus were manipulated in enclosures placed in a humic coastal lagoon (Cabiúnas Lagoon, Macaé - RJ to evaluate the individual and interactive effects of resource availability (nutrients and light and food web configuration on the biomass and stoichiometry of periphyton and benthic grazers. Our findings suggest that light and nutrients interact to determine periphyton biomass and stoichiometry, which propagates to the consumer level. We observed a positive effect of the availability of nutrients on periphytic biomass and grazers' biomass, as well as a reduction of periphytic C∶N∶P ratios and an increase of grazers' N and P content. Low light availability constrained the propagation of nutrient effects on periphyton biomass and induced higher periphytic C∶N∶P ratios. The effects of fish presence strongly interacted with resource availability. In general, a positive effect of fish presence was observed for the total biomass of periphyton and grazer's biomass, especially with high resource availability, but the opposite was found for periphytic autotrophic biomass. Fish also had a significant effect on periphyton stoichiometry, but no effect was observed on grazers' stoichiometric ratios. In summary, we observed that the indirect effect of fish predation on periphyton biomass might be dependent on multiple resources and periphyton nutrient stoichiometric variation can affect consumers' stoichiometry.

  15. Feasibility of a SenseCam-assisted 24-h recall to reduce under-reporting of energy intake.

    Science.gov (United States)

    Gemming, L; Doherty, A; Kelly, P; Utter, J; Ni Mhurchu, C

    2013-10-01

    The SenseCam is a camera worn on a lanyard around the neck that automatically captures point-of-view images in response to movement, heat and light (every 20-30 s). This device may enhance the accuracy of self-reported dietary intake by assisting participants' recall of food and beverage consumption. It was the objective of this study to evaluate if the wearable camera, SenseCam, can enhance the 24-h dietary recall by providing visual prompts to improve recall of food and beverage consumption. Thirteen volunteer adults in Oxford, United Kingdom, were recruited. Participants wore the SenseCam for 2 days while continuing their usual daily activities. On day 3, participants' diets were assessed using an interviewer-administered 24-h recall. SenseCam images were then shown to the participants and any additional dietary information that participants provided after viewing the images was recorded. Energy and macronutrient intakes were compared between the 24-h recall and 24-h recall+SenseCam. Data from 10 participants were included in the final analysis (8 males and 2 females), mean age 33 ± 11 years, mean BMI 25.9 ± 5.1 kg/m(2). Viewing the SenseCam images increased self-reported energy intake by approximately 1432 ± 1564 kJ or 12.5% compared with the 24-h recall alone (P=0.02). The increase was predominantly due to reporting of 41 additional foods (241 vs 282 total foods) across a range of food groups. Eight changes in portion size were made, which resulted in a negligible change to energy intake. Wearable cameras are promising method to enhance the accuracy of self-reported dietary assessment methods.

  16. Non-goal-directed recall of specific events in apes after long delays.

    Science.gov (United States)

    Lewis, Amy; Call, Josep; Berntsen, Dorthe

    2017-07-12

    We examined if apes spontaneously remember one-time, distinctive events across long delays when probed by discriminant cues. Apes witnessed an experimenter hide a cache of food, which they could then retrieve. They retrieved one of two food types; one more distinctive than the other. Two, 10 or 50 weeks later, the apes returned to the same enclosure and found a piece of the previously hidden food on the ground. An experimenter who had not hidden the food was also present. Apes immediately searched the location where the food was previously hidden (no food was here), showing recall of the event. One week later, apes returned to the same enclosure, with the same food on the ground, but now the experimenter that had hidden the food was present. Again, apes immediately searched the hiding location. Apes that had not witnessed the hiding event did not search. There was no significant effect of food type, and retention declined from exposure to the two-week delay, then levelled, consistent with the forgetting curve in humans (Ebbinghaus, H. 1964 Memory: a contribution to experimental psychology (transl. H.A. Ruger & C.E. Bussenvis). New York, NY: Dover. (Original work published 1885.)). This is the first study to show apes can recall a one-time, non-goal-directed event longer than two weeks ago and that apes' recall declines in accordance with a standard retention function. © 2017 The Author(s).

  17. How habitat-modifying organisms structure the food web of two coastal ecosystems

    NARCIS (Netherlands)

    Van der Zee, E.M.; Angelini, C.; Govers, L.; Christianen, M.J.A.; Altieri, A.H.; van der Reijden, K.J.; Silliman, B.R.; van de Koppel, J.; van der Geest, M.; van Gils, J.A.; van der Veer, H.W.; Piersma, T.; de Ruiter, P.C.; Olff, H.; van der Heide, T.

    2016-01-01

    The diversity and structure of ecosystems has been found to depend both ontrophic interactions in food webs and on other species interactions such ashabitat modification and mutualism that form non-trophic interactionnetworks. However, quantification of the dependencies between these twomain

  18. Is benthic food web structure related to diversity of marine macrobenthic communities?

    NARCIS (Netherlands)

    Sokolowski, A.; Wolowicz, M.; Asmus, H.; Asmus, R.; Carlier, A.; Gasiunaite, Z.; Gremare, A.; Hummel, H.; Lesutiene, J.; Razinkovas, A.; Renaud, P.E.; Richard, P.; Kedra, M.

    2012-01-01

    Numerical structure and the organisation of food webs within macrozoobenthic communities has been assessed in the European waters (Svalbard, Barents Sea, Baltic Sea, North Sea, Atlantic Ocean and the Mediterranean Sea) to address the interactions between biodiversity and ecosystem functioning.

  19. Influence of water mixing and food web status on the response of planktonic communities to enhanced ultraviolet-B radiation

    Science.gov (United States)

    Mostajir, B.; Uvbr Team

    2003-04-01

    Two series of mesocosm experiments were carried out in 1996 and 1997 using the natural planktonic assemblage, ultraviolet-B radiation (UVBR: 280-320 nm) at the community level. The water used in the first experiment was rich in nitrate (ca. 8-10 μM) and phytoplankton biomass (5 μg Chlorophyll a L-1: Chl a), conditions typical of an eutrophic coastal zone with herbivorous food web characteristics. In contrast, the water used in the second experiment was poor in nitrate (food web. Furthermore, to understand the influence of vertical mixing on the effects of UVBR on the planktonic community, two mixing regimes (fast and slow) were tested during the mesocosm experiments of 1997. The results showed that the mixing regime can moderate the effects of UVBR on the planktonic community and can also modify completely the species composition in the mesocosms much more than the UVBR. Comparison between the impact of UVBR on the planktonic community presented in these two experiments suggested that regenerated production-based systems (e.g. microbial food webs) tolerate the effects of UVBR more efficiently than do new production-based systems (herbivorous food webs). Results regarding the potential effects of UVBR in different marine systems, coastal versus oceanic, where different physical systems dominate, fast versus slow mixing, and consequently the development of different food webs are favored, herbivorous versus microbial, will be discussed.

  20. Adaptive behaviour, tri-trophic food-web stability and damping of chaos

    DEFF Research Database (Denmark)

    Visser, Andre; Mariani, Patrizio; Pigolotti, Simone

    2012-01-01

    We examine the effect of adaptive foraging behaviour within a tri-trophic food web with intra-guild predation. The intra-guild prey is allowed to adjust its foraging effort so as to achieve an optimal per capita growth rate in the face of realized feeding, predation risk and foraging cost. Adapti...

  1. Stable isotope evidence of food web connectivity by a top predatory ...

    African Journals Online (AJOL)

    In this study, food web connectivity within the Kowie Estuary on the south-east coast of South Africa was evidenced by the trophic behaviour of the predominantly piscivorous Argyrosomus japonicus. We examined stable isotopes of carbon (δ 13C) and nitrogen (δ 15N) in the dominant consumers (zooplankton, invertebrates ...

  2. Parasites in marine food webs

    Science.gov (United States)

    Lafferty, Kevin D.

    2013-01-01

    Most species interactions probably involve parasites. This review considers the extent to which marine ecologists should consider parasites to fully understand marine communities. Parasites are influential parts of food webs in estuaries, temperate reefs, and coral reefs, but their ecological importance is seldom recognized. Though difficult to observe, parasites can have substantial biomass, and they can be just as common as free-living consumers after controlling for body mass and trophic level. Parasites have direct impacts on the energetics of their hosts and some affect host behaviors, with ecosystem-level consequences. Although they cause disease, parasites are sensitive components of ecosystems. In particular, they suffer secondary extinctions due to biodiversity loss. Some parasites can also return to a system after habitat restoration. For these reasons, parasites can make good indicators of ecosystem integrity. Fishing can indirectly increase or decrease parasite populations and the effects of climate change on parasites are likely to be equally as complex.

  3. Mercury flow through an Asian rice-based food web

    International Nuclear Information System (INIS)

    Abeysinghe, Kasun S.; Qiu, Guangle; Goodale, Eben; Anderson, Christopher W.N.; Bishop, Kevin; Evers, David C.; Goodale, Morgan W.; Hintelmann, Holger; Liu, Shengjie

    2017-01-01

    Mercury (Hg) is a globally-distributed pollutant, toxic to humans and animals. Emissions are particularly high in Asia, and the source of exposure for humans there may also be different from other regions, including rice as well as fish consumption, particularly in contaminated areas. Yet the threats Asian wildlife face in rice-based ecosystems are as yet unclear. We sought to understand how Hg flows through rice-based food webs in historic mining and non-mining regions of Guizhou, China. We measured total Hg (THg) and methylmercury (MeHg) in soil, rice, 38 animal species (27 for MeHg) spanning multiple trophic levels, and examined the relationship between stable isotopes and Hg concentrations. Our results confirm biomagnification of THg/MeHg, with a high trophic magnification slope. Invertivorous songbirds had concentrations of THg in their feathers that were 15x and 3x the concentration reported to significantly impair reproduction, at mining and non-mining sites, respectively. High concentrations in specialist rice consumers and in granivorous birds, the later as high as in piscivorous birds, suggest rice is a primary source of exposure. Spiders had the highest THg concentrations among invertebrates and may represent a vector through which Hg is passed to vertebrates, especially songbirds. Our findings suggest there could be significant population level health effects and consequent biodiversity loss in sensitive ecosystems, like agricultural wetlands, across Asia, and invertivorous songbirds would be good subjects for further studies investigating this possibility. - Highlights: • Hg concentrations were measured across rice-based food webs in Guizhou, China. • Of 38 animal species, THg concentrations were highest for invertivorous songbirds. • High THg levels in rice pests and in granivorous birds suggest rice as a source. • Levels of THg in songbird feathers at mining site were among highest ever recorded. • Even at non-mining site, THg in such

  4. Trophodynamics of the Hanna Shoal Ecosystem (Chukchi Sea, Alaska): Connecting multiple end-members to a rich food web

    Science.gov (United States)

    McTigue, N. D.; Dunton, K. H.

    2017-10-01

    Predicting how alterations in sea ice-mediated primary production will impact Arctic food webs remains a challenge in forecasting ecological responses to climate change. One top-down approach to this challenge is to elucidate trophic roles of consumers as either specialists (i.e., consumers of predominantly one food resource) or generalists (i.e., consumers of multiple food resources) to categorize the dependence of consumers on each primary producer. At Hanna Shoal in the Chukchi Sea, Alaska, we used stable carbon and nitrogen isotope data to quantify trophic redundancy with standard ellipse areas at both the species and trophic guild levels. We also investigated species-level trophic plasticity by analyzing the varying extents that three end-members were assimilated by the food web using the mixing model simmr (Stable Isotope Mixing Model in R). Our results showed that ice algae, a combined phytoplankton and sediment organic matter composite (PSOM), and a hypothesized microphytobenthos (MPB) component were incorporated by consumers in the benthic food web, but their importance varied by species. Some primary consumers relied heavily on PSOM (e.g, the amphipods Ampelisca sp. and Byblis sp.; the copepod Calanus sp.), while others exhibited generalist feeding and obtained nutrition from multiple sources (e.g., the holothuroidean Ocnus glacialis, the gastropod Tachyrhynchus sp., the sipunculid Golfingia margaritacea, and the bivalves Ennucula tenuis, Nuculana pernula, Macoma sp., and Yoldia hyperborea). Most higher trophic level benthic predators, including the gastropods Buccinum sp., Cryptonatica affinis, and Neptunea sp, the seastar Leptasterias groenlandica, and the amphipod Anonyx sp. also exhibited trophic plasticity by coupling energy pathways from multiple primary producers including PSOM, ice algae, and MPB. Our stable isotope data indicate that consumers in the Hanna Shoal food web exhibit considerable trophic redundancy, while few species were specialists

  5. Mobilizing the regional eco-economy: evolving webs of agri-food and rural development in the UK

    OpenAIRE

    Terry Marsden

    2010-01-01

    The paper traces the emergence of the regional eco-economy with reference to a new conceptual model called the rural web. These webs are embedded into the fabric of regional systems of production and consumption and provide a key driver for both rural development generally and eco-economic development more specifically. Relocalized agri-food networks are playing a key integrating role in mobilizing the web and the regional eco-economy more generally. The web concept is used to (i) assess the ...

  6. Trophic coupling between two adjacent benthic food webs within a man-made intertidal area: A stable isotopes evidence

    Science.gov (United States)

    Schaal, Gauthier; Riera, Pascal; Leroux, Cédric

    2008-04-01

    This study aimed at establishing the effects of human-made physical modifications on the trophic structure and functioning of an intertidal benthic food web in Arcachon Bay (France). The main food sources and the most representative consumers were sampled on an artificial rocky dyke and its adjacent seagrass meadow. The food sources of consumers were inferred through the use of carbon and nitrogen stable isotopes. The contributions of the different food sources to the diets of the consumers were established using the Isosource mixing model. In order to reduce the range of feasible contributions, additional non-isotopic constraints were added when necessary to the outputs of this model. We observed a more complex food web than previously shown for artificial habitats. Moreover, it appears that several consumers inhabiting the artificial environment base most of their diet on allochtonous eelgrass-derived detritus. In turn, several consumers inhabiting the eelgrass meadow consumed significantly macroalgae-derived material originating from the adjacent artificial rocky area. These results point out that the food webs associated to adjacent habitats can influence each other through the utilisation of exported organic matter.

  7. Differential mercury transfer in the aquatic food web of a double basined lake associated with selenium and habitat

    International Nuclear Information System (INIS)

    Arcagni, Marina; Campbell, Linda; Arribére, María A.; Marvin-DiPasquale, Mark; Rizzo, Andrea; Ribeiro Guevara, Sergio

    2013-01-01

    Food web trophodynamics of total mercury (THg) and selenium (Se) were assessed for the double-basined ultraoligotrophic system of Lake Moreno, Patagonia. Each basin has differing proportions of littoral and pelagic habitats, thereby providing an opportunity to assess the importance of habitat (e.g. food web structure or benthic MeHg production) in the transfer of Hg and Se to top trophic fish species. Pelagic plankton, analyzed in three size classes (10–53, 53–200, and > 200 μm), had very high [THg], exceeding 200 μg g −1 dry weight (DW) in the smallest, and a low ratio of MeHg to THg (0.1 to 3%). In contrast, [THg] in littoral macroinvertebrates showed lower values (0.3 to 1.8 μg g −1 DW). Juvenile and small fish species feeding upon plankton had higher [THg] (0.2 to 8 μg g −1 muscle DW) compared to large piscivore fish species (0.1 to 1.6 μg g −1 muscle DW). Selenium concentrations exhibited a much narrower variation range than THg in the food web, varying from 0.5 to 2.7 μg g −1 DW. Molar Se:Hg ratios exceeded 1 for the majority of organisms in both basins, with most ratios exceeding 10. Using stable nitrogen isotopes as indicator of trophic level, no significant correlations were found with [THg], [Se] or Se:Hg. The apparent lack of biomagnification trends was attributed to elevated [THg] in plankton in the inorganic form mostly, as well as the possibility of consistent Se supply reducing the biomagnification in the food web of the organic portion of THg. Highlights: • Mercury was studied in the food web of Lake Moreno, Nahuel Huapi National Park. • Mercury trophic transfer was assessed by nitrogen stable isotope (δ 15 N) analysis. • Selenium was determined showing consistent source in pelagic and littoral organisms. • High mercury concentrations, mostly inorganic, were determined in plankton. • No mercury biomagnification was observed in Lake Moreno food web

  8. Micro-Food Web Structure Shapes Rhizosphere Microbial Communities and Growth in Oak

    Directory of Open Access Journals (Sweden)

    Hazel R. Maboreke

    2018-03-01

    Full Text Available The multitrophic interactions in the rhizosphere impose significant impacts on microbial community structure and function, affecting nutrient mineralisation and consequently plant performance. However, particularly for long-lived plants such as forest trees, the mechanisms by which trophic structure of the micro-food web governs rhizosphere microorganisms are still poorly understood. This study addresses the role of nematodes, as a major component of the soil micro-food web, in influencing the microbial abundance and community structure as well as tree growth. In a greenhouse experiment with Pedunculate Oak seedlings were grown in soil, where the nematode trophic structure was manipulated by altering the proportion of functional groups (i.e., bacterial, fungal, and plant feeders in a full factorial design. The influence on the rhizosphere microbial community, the ectomycorrhizal symbiont Piloderma croceum, and oak growth, was assessed. Soil phospholipid fatty acids were employed to determine changes in the microbial communities. Increased density of singular nematode functional groups showed minor impact by increasing the biomass of single microbial groups (e.g., plant feeders that of Gram-negative bacteria, except fungal feeders, which resulted in a decline of all microorganisms in the soil. In contrast, inoculation of two or three nematode groups promoted microbial biomass and altered the community structure in favour of bacteria, thereby counteracting negative impact of single groups. These findings highlight that the collective action of trophic groups in the soil micro-food web can result in microbial community changes promoting the fitness of the tree, thereby alleviating the negative effects of individual functional groups.

  9. The importance of landscape and spatial structure for hymenopteran-based food webs in an agro-ecosystem.

    Science.gov (United States)

    Fabian, Yvonne; Sandau, Nadine; Bruggisser, Odile T; Aebi, Alex; Kehrli, Patrik; Rohr, Rudolf P; Naisbit, Russell E; Bersier, Louis-Félix

    2013-11-01

    1. Understanding the environmental factors that structure biodiversity and food webs among communities is central to assess and mitigate the impact of landscape changes. 2. Wildflower strips are ecological compensation areas established in farmland to increase pollination services and biological control of crop pests and to conserve insect diversity. They are arranged in networks in order to favour high species richness and abundance of the fauna. 3. We describe results from experimental wildflower strips in a fragmented agricultural landscape, comparing the importance of landscape, of spatial arrangement and of vegetation on the diversity and abundance of trap-nesting bees, wasps and their enemies, and the structure of their food webs. 4. The proportion of forest cover close to the wildflower strips and the landscape heterogeneity stood out as the most influential landscape elements, resulting in a more complex trap-nest community with higher abundance and richness of hosts, and with more links between species in the food webs and a higher diversity of interactions. We disentangled the underlying mechanisms for variation in these quantitative food web metrics. 5. We conclude that in order to increase the diversity and abundance of pollinators and biological control agents and to favour a potentially stable community of cavity-nesting hymenoptera in wildflower strips, more investment is needed in the conservation and establishment of forest habitats within agro-ecosystems, as a reservoir of beneficial insect populations. © 2013 The Authors. Journal of Animal Ecology © 2013 British Ecological Society.

  10. Potential for Increased Mercury Accumulation in the Estuary Food Web

    Directory of Open Access Journals (Sweden)

    Jay A Davis

    2003-10-01

    Full Text Available Present concentrations of mercury in large portions of San Francisco Bay (Bay, the Sacramento-San Joaquin Delta (Delta, and the Sacramento and San Joaquin rivers are high enough to warrant concern for the health of humans and wildlife. Large scale tidal wetland restoration is currently under consideration as a means of increasing populations of fish species of concern. Tidal wetland restoration activities may lead to increased concentrations of mercury in the estuarine food web and exacerbate the existing mercury problem. This paper evaluates our present ability to predict the local and regional effects of restoration actions on mercury accumulation in aquatic food webs. A sport fish consumption advisory is in place for the Bay, and an advisory is under consideration for the Delta and lower Sacramento and San Joaquin rivers. Mercury concentrations in eggs of several water bird species from the Bay have exceeded the lowest observed effect level. A variety of mercury sources, largely related to historic mercury and gold mining, is present in the watershed and has created a spatially heterogeneous distribution of mercury in the Bay-Delta Estuary. Mercury exists in the environment in a variety of forms and has a complex biogeochemical cycle. The most hazardous form, methylmercury, is produced at a relatively high rate in wetlands and newly flooded aquatic habitats. It is likely that distinct spatial variation on multiple spatial scales exists in net methylmercury production in Bay-Delta tidal wetlands, including variation within each tidal wetland, among tidal wetlands in the same region, and among tidal wetlands in different regions. Understanding this spatial variation and its underlying causes will allow environmental managers to minimize the negative effects of mercury bioaccumulation as a result of restoration activities. Actions needed to reduce the uncertainty associated with this issue include a long term, multifaceted research effort, long

  11. Feeding by larvae of intertidal invertebrates: assessing their position in pelagic food webs.

    Science.gov (United States)

    Vargas, Cristian A; Manríquez, Patricio H; Navarrete, Sergio A

    2006-02-01

    One of the leading determinants of the structure and dynamics of marine populations is the rate of arrival of new individuals to local sites. While physical transport processes play major roles in delivering larvae to the shore, these processes become most important after larvae have survived the perils of life in the plankton, where they usually suffer great mortality. The lack of information regarding larval feeding makes it difficult to assess the effects of food supply on larval survival, or the role larvae may play in nearshore food webs. Here, we examine the spectrum of food sizes and food types consumed by the larvae of two intertidal barnacle species and of the predatory gastropod Concholepas concholepas. We conducted replicated experiments in which larvae were exposed to the food size spectrum (phytoplankton, microprotozoan and autotrophic picoplankton) found in nearshore waters in central Chile. Results show that barnacle nauplii and gastropod veligers are omnivorous grazers, incorporating significant fractions of heterotrophs in their diets. In accordance with their feeding mechanisms and body size, barnacle nauplii were able to feed on autotrophic picoplankton (concholepas larvae also consumed picoplankton cells, while competent larvae of this species ingested mostly the largest phytoplankton cells and heterotrophic protozoans. Results suggest that persistent changes in the structure of pelagic food webs can have important effects on the species-specific food availability for invertebrate larvae, which can result in large-scale differences in recruitment rates of a given species, and in the relative recruitment success of the different species that make up benthic communities.

  12. Low concentrations of selenium in stream food webs of eastern Canada

    International Nuclear Information System (INIS)

    Jardine, Timothy D.; Kidd, Karen A.

    2011-01-01

    Herbivorous and predatory invertebrates and two species of fish (brook trout and blacknose dace) were collected from 49 streams in New Brunswick, Canada to determine whether concentrations of selenium (Se) in the biota were affected by a point source (a coal-fired power plant), and stream water chemistry (pH, sulphate, conductivity, and total organic carbon), and to determine the trophic transfer of Se through these food webs. Total Se concentrations in the biota were generally low (0.2 to 4.8 μg g -1 dry weight) across sites and there was no relationship between distance from the coal-fired power plant and Se concentrations in invertebrates or fishes. Water chemistry was an equally poor predictor of Se concentrations in invertebrates and fish. Trophic position (determined using δ 15 N) was a significant predictor of Se concentrations in only five of the stream food webs, and two of these had negative slopes, indicating little or no trophic magnification across most systems; many fishes had lower concentrations than their invertebrate prey and trophic transfer was higher at sites with low invertebrate Se concentrations. Variability in Se concentrations in fishes was explained more by site of capture than microhabitat use within the site (as measured with δ 13 C), suggesting among-site differences in geological sources of Se. Because concentrations were below known toxicity thresholds for fish and other consumers, these results suggest that Se is not an environmental issue in New Brunswick streams that do not receive direct inputs from mining activities. - Research Highlights: → Se concentrations in stream invertebrates and fishes in eastern Canada are low. → Concentrations were not related to water chemistry or distance from a point source. → Se did not biomagnify in the food web, yet was almost always in excess of Hg.

  13. How habitat-modifying organisms structure the food web of two coastal ecosystems

    NARCIS (Netherlands)

    van der Zee, Els M; Angelini, Christine; Govers, Laura L; Christianen, Marjolijn J A; Altieri, Andrew H; van der Reijden, Karin J; Silliman, Brian R; van de Koppel, Johan; van der Geest, Matthijs; van Gils, Jan A; van der Veer, Henk W; Piersma, Theunis; de Ruiter, Peter C; Olff, Han; van der Heide, Tjisse

    2016-01-01

    The diversity and structure of ecosystems has been found to depend both on trophic interactions in food webs and on other species interactions such as habitat modification and mutualism that form non-trophic interaction networks. However, quantification of the dependencies between these two main

  14. Impact of freshwater influx on microzooplankton mediated food web in a tropical estuary (Cochin backwaters - India)

    Digital Repository Service at National Institute of Oceanography (India)

    Jyothibabu, R; Madhu, N.V.; Jayalakshmi, K.V.; Balachandran, K.K.; Shiyas, C.C.; Martin, G.D.; Nair, K.K.C.

    -1 Impact of fresh water influx on microzooplankton mediated food web in a tropical estuary (Cochin backwaters - India) R. Jyothibabu A, B, N.V. Madhu A, K.V. Jayalakshmi A, K. K. Balachandran A, C. A. Shiyas A, G. D. Martin A and K. K. C. Nair A A... in the northeastern Atlantic Ocean. Deep Sea Research 40, 479 ? 493. Burkill, P. H., Leaky, R. J. G., Owens, N. J. P., and Mantoura, R. F. C., 1993b. Synechococcus and its importance to the microbial food web of the northwestern Indian Ocean, In: Biogeochemical...

  15. Carbon transfer in herbivore- and microbial loop-dominated pelagic food webs in the southern Barents Sea during spring and summer

    NARCIS (Netherlands)

    De Laender, F.; Oevelen, D. van; Soetaert, K.; Middelburg, J.J.

    2010-01-01

    We compared carbon budgets between a herbivore-dominated and a microbial loopdominated food web and examined the implications of food web structure for fish production. We used the southern Barents Sea as a case study and inverse modelling as an analysis method. In spring, when the system was

  16. Expanding the isotopic toolbox: Applications of hydrogen and oxygen stable isotope ratios to food web studies

    Directory of Open Access Journals (Sweden)

    Hannah B Vander Zanden

    2016-03-01

    Full Text Available The measurement of stable carbon (δ13C and nitrogen (δ15N isotopes in tissues of organisms has formed the foundation of isotopic food web reconstructions, as these values directly reflect assimilated diet. In contrast, stable hydrogen (δ2H and oxygen (δ18O isotope measurements have typically been reserved for studies of migratory origin and paleoclimate reconstruction based on systematic relationships between organismal tissue and local environmental water. Recently, innovative applications using δ2H and, to a lesser extent, δ18O values have demonstrated potential for these elements to provide novel insights in modern food web studies. We explore the advantages and challenges associated with three applications of δ2H and δ18O values in food web studies. First, large δ2H differences between aquatic and terrestrial ecosystem end members can permit the quantification of energy inputs and nutrient fluxes between these two sources, with potential applications for determining allochthonous vs. autochthonous nutrient sources in freshwater systems and relative aquatic habitat utilization by terrestrial organisms. Next, some studies have identified a relationship between δ2H values and trophic position, which suggests that this marker may serve as a trophic indicator, in addition to the more commonly used δ15N values. Finally, coupled measurements of δ2H and δ18O values are increasing as a result of reduced analytical challenges to measure both simultaneously and may provide additional ecological information over single element measurements. In some organisms, the isotopic ratios of these two elements are tightly coupled, whereas the isotopic disequilibrium in other organisms may offer insight into the diet and physiology of individuals. Although a coherent framework for interpreting δ2H and δ18O data in the context of food web studies is emerging, many fundamental uncertainties remain. We highlight directions for targeted research that

  17. Longer and less overlapping food webs in anthropogenically disturbed marine ecosystems: confirmations from the past.

    Directory of Open Access Journals (Sweden)

    Fabiana Saporiti

    Full Text Available The human exploitation of marine resources is characterised by the preferential removal of the largest species. Although this is expected to modify the structure of food webs, we have a relatively poor understanding of the potential consequences of such alteration. Here, we take advantage of a collection of ancient consumer tissues, using stable isotope analysis and SIBER to assess changes in the structure of coastal marine food webs in the South-western Atlantic through the second half of the Holocene as a result of the sequential exploitation of marine resources by hunter-gatherers, western sealers and modern fishermen. Samples were collected from shell middens and museums. Shells of both modern and archaeological intertidal herbivorous molluscs were used to reconstruct changes in the stable isotopic baseline, while modern and archaeological bones of the South American sea lion Otaria flavescens, South American fur seal Arctocephalus australis and Magellanic penguin Spheniscus magellanicus were used to analyse changes in the structure of the community of top predators. We found that ancient food webs were shorter, more redundant and more overlapping than current ones, both in northern-central Patagonia and southern Patagonia. These surprising results may be best explained by the huge impact of western sealing on pinnipeds during the fur trade period, rather than the impact of fishing on fish populations. As a consequence, the populations of pinnipeds at the end of the sealing period were likely well below the ecosystem's carrying capacity, which resulted in a release of intraspecific competition and a shift towards larger and higher trophic level prey. This in turn led to longer and less overlapping food webs.

  18. Recall of vegetable eating affects future predicted enjoyment and choice of vegetables in British University undergraduate students.

    Science.gov (United States)

    Robinson, Eric; Blissett, Jackie; Higgs, Suzanne

    2011-10-01

    Predictions about enjoyment of future experiences are influenced by recalling similar past experiences. However, little is known about the relationship between hedonic memories of past eating episodes and future eating behavior. We investigated recall of previous experiences of eating vegetables and the effect of recall on future predicted liking for and consumption of vegetables. British University undergraduate students were asked to retrieve memories of previous occasions when they ate vegetables and were asked to rate how enjoyable those experiences were (Study 1, n=54). The effect of different types of memory recall (including vegetable eating recall) and visualization of someone else eating vegetables (to control for priming effects) on predicted likelihood of choosing vegetables and predicted enjoyment of eating vegetables was examined (Study 2, n=95). Finally, the effect of recalling vegetable eating memories on actual food choice from a buffet was assessed (Study 3, n=63). It is reported that people recall positive memories of past vegetable consumption (Precall of a personal nonfood memory, a nonvegetable food memory, or visualization of someone else enjoying eating vegetables (increase of approximately 70% in vegetable portion size compared to controls). The results suggest that recall of previous eating experiences could be a potential strategy for altering food choices. Copyright © 2011 American Dietetic Association. Published by Elsevier Inc. All rights reserved.

  19. Trophic linkage of a temperate intertidal macrobenthic food web under opportunistic macroalgal blooms: A stable isotope approach

    International Nuclear Information System (INIS)

    Park, Hyun Je; Han, Eunah; Lee, Young-Jae; Kang, Chang-Keun

    2016-01-01

    The effects of blooms of opportunistic green macroalgae, Ulva prolifera, on the trophic structure of the macrobenthic food web in a temperate intertidal zone on the western coast of Korea were evaluated using carbon and nitrogen stable isotopes. Biomasses of Ulva and microphytobenthos (MPB) increased significantly at the macroalgae-bloom and the non-bloom sites, respectively, from March to September 2011. The δ 13 C values of most the consumers were arrayed between those of MPB and Ulva at both sites, and differed according to feeding strategies at the macroalgae-bloom site. Seasonally increasing magnitudes in δ 13 C and δ 15 N values of consumers were much steeper at the macroalgae-bloom site than at the non-bloom site. Our findings provide evidence that blooming green macroalgae play a significant role as a basal resource supporting the intertidal macrobenthic food web and their significance varies with feeding strategies of consumers as well as the resource availability. - Highlights: • Trophic effects of Ulva blooms on intertidal macrobenthic food web were evaluated. • Biomasses of Ulva increased at the macroalgae-bloom from March to September. • δ 13 C and δ 15 N values of consumers differed with feeding strategy and season. • Trophic significance of blooming macroalgae varies with feeding strategies of consumers. • Ulva blooms play a significant role as a basal resource supporting the intertidal food web.

  20. Methylmercury enters an aquatic food web through acidophilic microbial mats in Yellowstone National Park, Wyoming.

    Science.gov (United States)

    Boyd, Eric S; King, Susan; Tomberlin, Jeffery K; Nordstrom, D Kirk; Krabbenhoft, David P; Barkay, Tamar; Geesey, Gill G

    2009-04-01

    Microbial mats are a visible and abundant life form inhabiting the extreme environments in Yellowstone National Park (YNP), WY, USA. Little is known of their role in food webs that exist in the Park's geothermal habitats. Eukaryotic green algae associated with a phototrophic green/purple Zygogonium microbial mat community that inhabits low-temperature regions of acidic (pH approximately 3.0) thermal springs were found to serve as a food source for stratiomyid (Diptera: Stratiomyidae) larvae. Mercury in spring source water was taken up and concentrated by the mat biomass. Monomethylmercury compounds (MeHg(+)), while undetectable or near the detection limit (0.025 ng l(-1)) in the source water of the springs, was present at concentrations of 4-7 ng g(-1) dry weight of mat biomass. Detection of MeHg(+) in tracheal tissue of larvae grazing the mat suggests that MeHg(+) enters this geothermal food web through the phototrophic microbial mat community. The concentration of MeHg(+) was two to five times higher in larval tissue than mat biomass indicating MeHg(+) biomagnification occurred between primary producer and primary consumer trophic levels. The Zygogonium mat community and stratiomyid larvae may also play a role in the transfer of MeHg(+) to species in the food web whose range extends beyond a particular geothermal feature of YNP.

  1. Productivity and linkages of the food web of the southern region of the western Antarctic Peninsula continental shelf

    Science.gov (United States)

    Ballerini, Tosca; Hofmann, Eileen E.; Ainley, David G.; Daly, Kendra; Marrari, Marina; Ribic, Christine A.; Smith, Walker O.; Steele, John H.

    2014-03-01

    The productivity and linkages in the food web of the southern region of the west Antarctic Peninsula continental shelf were investigated using a multi-trophic level mass balance model. Data collected during the Southern Ocean Global Ocean Ecosystem Dynamics field program were combined with data from the literature on the abundance and diet composition of zooplankton, fish, seabirds and marine mammals to calculate energy flows in the food web and to infer the overall food web structure at the annual level. Sensitivity analyses investigated the effects of variability in growth and biomass of Antarctic krill (Euphausia superba) and in the biomass of Antarctic krill predators on the structure and energy fluxes in the food web. Scenario simulations provided insights into the potential responses of the food web to a reduced contribution of large phytoplankton (diatom) production to total primary production, and to reduced consumption of primary production by Antarctic krill and mesozooplankton coincident with increased consumption by microzooplankton and salps. Model-derived estimates of primary production were 187-207 g C m-2 y-1, which are consistent with observed values (47-351 g C m-2 y-1). Simulations showed that Antarctic krill provide the majority of energy needed to sustain seabird and marine mammal production, thereby exerting a bottom-up control on higher trophic level predators. Energy transfer to top predators via mesozooplanton was a less efficient pathway, and salps were a production loss pathway because little of the primary production they consumed was passed to higher trophic levels. Increased predominance of small phytoplankton (nanoflagellates and cryptophytes) reduced the production of Antarctic krill and of its predators, including seabirds and seals.

  2. Bioaccumulation of per- and polyfluorinated alkyl substances (PFAS) in selected species from the Barents Sea food web.

    Science.gov (United States)

    Haukås, Marianne; Berger, Urs; Hop, Haakon; Gulliksen, Bjørn; Gabrielsen, Geir W

    2007-07-01

    The present study reports concentrations and biomagnification potential of per- and polyfluorinated alkyl substances (PFAS) in species from the Barents Sea food web. The examined species included sea ice amphipod (Gammarus wilkitzkii), polar cod (Boreogadus saida), black guillemot (Cepphus grylle) and glaucous gull (Larus hyperboreus). These were analyzed for PFAS, polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs) and polybrominated diphenyl ethers (PBDEs). Perfluorooctane sulfonate (PFOS) was the predominant of the detected PFAS. Trophic levels and food web transfer of PFAS were determined using stable nitrogen isotopes (delta(15)N). No correlation was found between PFOS concentrations and trophic level within species. However, a non-linear relationship was established when the entire food web was analyzed. Biomagnification factors displayed values >1 for perfluorohexane sulfonate (PFHxS), perfluorononanoic acid (PFNA), PFOS and SigmaPFAS(7). Multivariate analyses showed that the degree of trophic transfer of PFAS is similar to that of PCB, DDT and PBDE, despite their accumulation through different pathways.

  3. Trophic relationships in a tropical stream food web assessed by stable isotope analysis

    OpenAIRE

    Coat, Sophie; Monti, Dominique; Bouchon, Claude; Lepoint, Gilles

    2009-01-01

    1. Stable isotope analysis, coupled with dietary data from the literature, was used to investigate trophic patterns of freshwater fauna in a tropical stream food web (Guadeloupe, French West Indies). 2. Primary producers (biofilm, algae and plant detritus of terrestrial origin) showed distinct delta C-13 signatures, which allowed for a powerful discrimination of carbon sources. Both autochthonous (C-13-enriched signatures) and allochthonous (C-13-depleted signatures) resources enter the food ...

  4. Benthic and pelagic pathways of methylmercury bioaccumulation in estuarine food webs of the northeast United States.

    Directory of Open Access Journals (Sweden)

    Celia Y Chen

    Full Text Available Methylmercury (MeHg is a contaminant of global concern that bioaccumulates and bioamagnifies in marine food webs. Lower trophic level fauna are important conduits of MeHg from sediment and water to estuarine and coastal fish harvested for human consumption. However, the sources and pathways of MeHg to these coastal fisheries are poorly known particularly the potential for transfer of MeHg from the sediment to biotic compartments. Across a broad gradient of human land impacts, we analyzed MeHg concentrations in food webs at ten estuarine sites in the Northeast US (from the Hackensack Meadowlands, NJ to the Gulf of Maine. MeHg concentrations in water column particulate material, but not in sediments, were predictive of MeHg concentrations in fish (killifish and Atlantic silversides. Moreover, MeHg concentrations were higher in pelagic fauna than in benthic-feeding fauna suggesting that MeHg delivery to the water column from methylation sites from within or outside of the estuary may be an important driver of MeHg bioaccumulation in estuarine pelagic food webs. In contrast, bulk sediment MeHg concentrations were only predictive of concentrations of MeHg in the infaunal worms. Our results across a broad gradient of sites demonstrate that the pathways of MeHg to lower trophic level estuarine organisms are distinctly different between benthic deposit feeders and forage fish. Thus, even in systems with contaminated sediments, transfer of MeHg into estuarine food webs maybe driven more by the efficiency of processes that determine MeHg input and bioavailability in the water column.

  5. New parasites and predators follow the introduction of two fish species to a subarctic lake: implications for food-web structure and functioning

    Science.gov (United States)

    Amundsen, Per-Arne; Lafferty, Kevin D.; Knudsen, Rune; Primicerio, Raul; Kristoffersen, Roar; Klemetsen, Anders; Kuris, Armand M.

    2012-01-01

    Introduced species can alter the topology of food webs. For instance, an introduction can aid the arrival of free-living consumers using the new species as a resource, while new parasites may also arrive with the introduced species. Food-web responses to species additions can thus be far more complex than anticipated. In a subarctic pelagic food web with free-living and parasitic species, two fish species (arctic charr Salvelinus alpinus and three-spined stickleback Gasterosteus aculeatus) have known histories as deliberate introductions. The effects of these introductions on the food web were explored by comparing the current pelagic web with a heuristic reconstruction of the pre-introduction web. Extinctions caused by these introductions could not be evaluated by this approach. The introduced fish species have become important hubs in the trophic network, interacting with numerous parasites, predators and prey. In particular, five parasite species and four predatory bird species depend on the two introduced species as obligate trophic resources in the pelagic web and could therefore not have been present in the pre-introduction network. The presence of the two introduced fish species and the arrival of their associated parasites and predators increased biodiversity, mean trophic level, linkage density, and nestedness; altering both the network structure and functioning of the pelagic web. Parasites, in particular trophically transmitted species, had a prominent role in the network alterations that followed the introductions.

  6. Drivers of nitrogen transfer in stream food webs across continents.

    Science.gov (United States)

    Norman, Beth C; Whiles, Matt R; Collins, Sarah M; Flecker, Alexander S; Hamilton, Steve K; Johnson, Sherri L; Rosi, Emma J; Ashkenas, Linda R; Bowden, William B; Crenshaw, Chelsea L; Crowl, Todd; Dodds, Walter K; Hall, Robert O; El-Sabaawi, Rana; Griffiths, Natalie A; Marti, Eugènia; McDowell, William H; Peterson, Scot D; Rantala, Heidi M; Riis, Tenna; Simon, Kevin S; Tank, Jennifer L; Thomas, Steven A; von Schiller, Daniel; Webster, Jackson R

    2017-12-01

    Studies of trophic-level material and energy transfers are central to ecology. The use of isotopic tracers has now made it possible to measure trophic transfer efficiencies of important nutrients and to better understand how these materials move through food webs. We analyzed data from thirteen 15 N-ammonium tracer addition experiments to quantify N transfer from basal resources to animals in headwater streams with varying physical, chemical, and biological features. N transfer efficiencies from primary uptake compartments (PUCs; heterotrophic microorganisms and primary producers) to primary consumers was lower (mean 11.5%, range 100%). Total N transferred (as a rate) was greater in streams with open compared to closed canopies and overall N transfer efficiency generally followed a similar pattern, although was not statistically significant. We used principal component analysis to condense a suite of site characteristics into two environmental components. Total N uptake rates among trophic levels were best predicted by the component that was correlated with latitude, DIN:SRP, GPP:ER, and percent canopy cover. N transfer efficiency did not respond consistently to environmental variables. Our results suggest that canopy cover influences N movement through stream food webs because light availability and primary production facilitate N transfer to higher trophic levels. © 2017 by the Ecological Society of America.

  7. Are algae relevant to the detritus-based food web in tank-bromeliads?

    Directory of Open Access Journals (Sweden)

    Olivier Brouard

    Full Text Available We assessed the occurrence of algae in five species of tank-bromeliads found in contrasting environmental sites in a Neotropical, primary rainforest around the Nouragues Research Station, French Guiana. The distributions of both algal abundance and biomass were examined based on physical parameters, the morphological characteristics of bromeliad species and with regard to the structure of other aquatic microbial communities held in the tanks. Algae were retrieved in all of the bromeliad species with mean densities ranging from ∼10(2 to 10(4 cells/mL. Their biomass was positively correlated to light exposure and bacterial biomass. Algae represented a tiny component of the detrital food web in shaded bromeliads but accounted for up to 30 percent of the living microbial carbon in the tanks of Catopsis berteroniana, located in a highly exposed area. Thus, while nutrient supplies are believed to originate from wind-borne particles and trapped insects (i.e., allochtonous organic matter, our results indicate that primary producers (i.e., autochtonous organic matter are present in this insectivorous bromeliad. Using a 24-h incubation of size-fractionated and manipulated samples from this plant, we evaluated the impact of mosquito foraging on algae, other microorganisms and rotifers. The prey assemblages were greatly altered by the predation of mosquito larvae. Grazing losses indicated that the dominant algal taxon, Bumilleriopsis sp., like protozoa and rotifers, is a significant part of the diet of mosquito larvae. We conclude that algae are a relevant functional community of the aquatic food web in C. berteroniana and might form the basis of a complementary non-detrital food web.

  8. Fatty acid biomarkers: validation of food web and trophic markers using C-13-labelled fatty acids in juvenile sandeel ( Ammodytes tobianus )

    DEFF Research Database (Denmark)

    Dalsgaard, Anne Johanne Tang; St. John, Michael

    2004-01-01

    A key issue in marine science is parameterizing trophic interactions in marine food webs, thereby developing an understanding of the importance of top-down and bottom-up controls on populations of key trophic players. This study validates the utility of fatty acid food web and trophic markers usi......), respectively. Lack of temporal trends in nonlabelled fatty acids confirmed the conservative incorporation of labelled fatty acids by the fish.......A key issue in marine science is parameterizing trophic interactions in marine food webs, thereby developing an understanding of the importance of top-down and bottom-up controls on populations of key trophic players. This study validates the utility of fatty acid food web and trophic markers using...... C-13-labelled fatty acids to verify the conservative incorporation of fatty acid tracers by juvenile sandeel (Ammodytes tobianus) and assess their uptake, clearance, and metabolic turnover rates. Juvenile sandeel were fed for 16 days in the laboratory on a formulated diet enriched in (13)C16...

  9. Biomagnification of mercury through lake trout (Salvelinus namaycush) food webs of lakes with different physical, chemical and biological characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Kidd, Karen A., E-mail: kiddk@unbsj.ca [Canadian Rivers Institute and Biology Department, University of New Brunswick, Saint John, NB, Canada E2L 4L5 (Canada); Muir, Derek C.G., E-mail: derek.muir@ec.gc.ca [Aquatic Contaminants Research Division, Environment Canada, Burlington, ON, Canada L7R 4A6 (Canada); Evans, Marlene S., E-mail: marlene.evans@ec.gc.ca [Aquatic Contaminants Research Division, Environment Canada, Saskatoon, SK, Canada S7N 3H5 (Canada); Wang, Xioawa, E-mail: xiaowa.wang@ec.gc.ca [Aquatic Contaminants Research Division, Environment Canada, Burlington, ON, Canada L7R 4A6 (Canada); Whittle, Mike [Aquatic Contaminants Research Division, Environment Canada, Burlington, ON, Canada L7R 4A6 (Canada); Swanson, Heidi K., E-mail: heidikswanson@yahoo.ca [Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada T6G 2E9 (Canada); Johnston, Tom, E-mail: tjohnston@laurentian.ca [Cooperative Freshwater Ecology Unit, Ontario Ministry of Natural Resources, and Biology Department, Laurentian University, Sudbury, ON, Canada P3E 2C6 (Canada); Guildford, Stephanie, E-mail: sguildfo@d.umn.edu [Department of Biology and Large Lakes Observatory, University of Minnesota Duluth, 2205 5th St., Duluth, MN, 55812 (United States)

    2012-11-01

    Mercury (Hg) biomagnification in aquatic ecosystems remains a concern because this pollutant is known to affect the health of fish-eating wildlife and humans, and the fish themselves. The 'rate' of mercury biomagnification is being assessed more frequently using stable nitrogen isotope ratios ({delta}{sup 15}N), a measure of relative trophic position of biota within a food web. Within food webs and across diverse systems, log-transformed Hg concentrations are significantly and positively related to {delta}{sup 15}N and the slopes of these models vary from one study to another for reasons that are not yet understood. Here we compared the rates of Hg biomagnification in 14 lake trout lakes from three provinces in Canada to understand whether any characteristics of the ecosystems explained this among-system variability. Several fish species, zooplankton and benthic invertebrates were collected from these lakes and analyzed for total Hg (fish only), methyl Hg (invertebrates) and stable isotopes ({delta}{sup 15}N; {delta}{sup 13}C to assess energy sources). Mercury biomagnification rates varied significantly across systems and were higher for food webs of larger (surface area), higher nutrient lakes. However, the slopes were not predictive of among-lake differences in Hg in the lake trout. Results indicate that among-system differences in the rates of Hg biomagnification seen in the literature may be due, in part, to differences in ecosystem characteristics although the mechanisms for this variability are not yet understood. -- Highlights: Black-Right-Pointing-Pointer Mercury biomagnifies through aquatic food webs to toxic levels in top predator fishes. Black-Right-Pointing-Pointer Among-system differences in mercury transfer through food webs occur but have not been explained. Black-Right-Pointing-Pointer Diverse lakes supporting lake trout were compared to understand the ecosystem processes that affect mercury biomagnification. Black

  10. Food web analysis reveals effects of pH on mercury bioaccumulation at multiple trophic levels in streams

    International Nuclear Information System (INIS)

    Jardine, Timothy D.; Kidd, Karen A.; O’ Driscoll, Nelson

    2013-01-01

    Highlights: ► We examine biomagnification of Hg through stream food webs using δ15 N. ► Slopes of methyl Hg vs. trophic level were higher than total Hg vs. trophic level. ► Biomagnification from predatory insects to fish was related to pH of the water. ► Biomagnification at lower trophic levels was related to dietary concentrations. ► These trends can explain variation in field-measured Hg in food webs. -- Abstract: Biomagnification processes and the factors that govern them, including those for mercury (Hg), are poorly understood in streams. Total and methyl Hg concentrations and relative trophic position (using δ 15 N) were analyzed in biofilm and invertebrates from 21 streams in New Brunswick, Canada to assess food web biomagnification leading to the common minnow blacknose dace (Rhinichthys atratulus), a species known to have Hg concentrations that are higher in low pH waters. Biomagnification slopes within stream food webs measured using Hg vs. δ 15 N or corresponding trophic levels (TL) differed depending on the chemical species analyzed, with total Hg exhibiting increases of 1.3–2.5 per TL (mean slope of total Hg vs. δ 15 N = 0.14 ± 0.06 S.D., range = 0.06–0.20) and methyl Hg showing a more pronounced increase of 2.8 to 6.0 per TL (mean slope of methyl Hg vs. δ 15 N = 0.30 ± 0.08 S.D., range = 0.22–0.39). While Hg biomagnification slopes through the entire food web (Trophic Magnification Factors, TMFs) were not influenced by water chemistry (pH), dietary concentrations of methyl Hg strongly influenced biomagnification factors (BMFs) for consumer-diet pairs within the food web at lower trophic levels, and BMFs between dace and predatory invertebrates were significantly higher in low pH waters. These analyses, coupled with observations of higher Hg in primary producers in streams with low pH, suggest that pH influences both baseline concentrations and biomagnification of Hg in these systems. Because higher Hg concentrations in the diets

  11. Food web analysis reveals effects of pH on mercury bioaccumulation at multiple trophic levels in streams

    Energy Technology Data Exchange (ETDEWEB)

    Jardine, Timothy D., E-mail: tim.jardine@usask.ca [Canadian Rivers Institute and Department of Biology, University of New Brunswick, Saint John, NB E2L 4L5 (Canada); Kidd, Karen A. [Canadian Rivers Institute and Department of Biology, University of New Brunswick, Saint John, NB E2L 4L5 (Canada); O’ Driscoll, Nelson [Department of Earth and Environmental Sciences, Acadia University, Wolfville, NS B4P 2R6 (Canada)

    2013-05-15

    Highlights: ► We examine biomagnification of Hg through stream food webs using δ15 N. ► Slopes of methyl Hg vs. trophic level were higher than total Hg vs. trophic level. ► Biomagnification from predatory insects to fish was related to pH of the water. ► Biomagnification at lower trophic levels was related to dietary concentrations. ► These trends can explain variation in field-measured Hg in food webs. -- Abstract: Biomagnification processes and the factors that govern them, including those for mercury (Hg), are poorly understood in streams. Total and methyl Hg concentrations and relative trophic position (using δ{sup 15}N) were analyzed in biofilm and invertebrates from 21 streams in New Brunswick, Canada to assess food web biomagnification leading to the common minnow blacknose dace (Rhinichthys atratulus), a species known to have Hg concentrations that are higher in low pH waters. Biomagnification slopes within stream food webs measured using Hg vs. δ{sup 15}N or corresponding trophic levels (TL) differed depending on the chemical species analyzed, with total Hg exhibiting increases of 1.3–2.5 per TL (mean slope of total Hg vs. δ{sup 15}N = 0.14 ± 0.06 S.D., range = 0.06–0.20) and methyl Hg showing a more pronounced increase of 2.8 to 6.0 per TL (mean slope of methyl Hg vs. δ{sup 15}N = 0.30 ± 0.08 S.D., range = 0.22–0.39). While Hg biomagnification slopes through the entire food web (Trophic Magnification Factors, TMFs) were not influenced by water chemistry (pH), dietary concentrations of methyl Hg strongly influenced biomagnification factors (BMFs) for consumer-diet pairs within the food web at lower trophic levels, and BMFs between dace and predatory invertebrates were significantly higher in low pH waters. These analyses, coupled with observations of higher Hg in primary producers in streams with low pH, suggest that pH influences both baseline concentrations and biomagnification of Hg in these systems. Because higher Hg

  12. Carbon transfer in a herbivore- and microbial loop-dominated pelagic food webs in the southern Barents Sea during spring and summer

    NARCIS (Netherlands)

    De Laender, F.; Van Oevelen, D.; Soetaert, K.E.R.; Middelburg, J.J.

    2010-01-01

    We compare carbon budgets between a herbivore-dominated and a microbial loop-dominated food web and examine the implications of food web structure for fish production. We use the southern Barents Sea as a case study and inverse modelling as an analysis method. In spring, when the system was

  13. Differential mercury transfer in the aquatic food web of a double basined lake associated with selenium and habitat

    Energy Technology Data Exchange (ETDEWEB)

    Arcagni, Marina [Laboratorio de Análisis por Activación Neutrónica, Centro Atómico Bariloche, CNEA, Av. Bustillo km 9.5, 8400 Bariloche (Argentina); Campbell, Linda [Faculty of Science, Saint Mary' s University, 923 Robie Street, Halifax, Nova Scotia B3H 3C3 (Canada); Arribére, María A. [Laboratorio de Análisis por Activación Neutrónica, Centro Atómico Bariloche, CNEA, Av. Bustillo km 9.5, 8400 Bariloche (Argentina); Instituto Balseiro, Universidad Nacional de Cuyo and Comisión Nacional de Energía Atómica (Argentina); Marvin-DiPasquale, Mark [U.S. Geological Survey, 345 Middlefield Rd./MS 480, Menlo Park, CA 94025 (United States); Rizzo, Andrea [Laboratorio de Análisis por Activación Neutrónica, Centro Atómico Bariloche, CNEA, Av. Bustillo km 9.5, 8400 Bariloche (Argentina); CONICET (Argentina); Ribeiro Guevara, Sergio, E-mail: ribeiro@cab.cnea.gov.ar [Laboratorio de Análisis por Activación Neutrónica, Centro Atómico Bariloche, CNEA, Av. Bustillo km 9.5, 8400 Bariloche (Argentina)

    2013-06-01

    Food web trophodynamics of total mercury (THg) and selenium (Se) were assessed for the double-basined ultraoligotrophic system of Lake Moreno, Patagonia. Each basin has differing proportions of littoral and pelagic habitats, thereby providing an opportunity to assess the importance of habitat (e.g. food web structure or benthic MeHg production) in the transfer of Hg and Se to top trophic fish species. Pelagic plankton, analyzed in three size classes (10–53, 53–200, and > 200 μm), had very high [THg], exceeding 200 μg g{sup −1} dry weight (DW) in the smallest, and a low ratio of MeHg to THg (0.1 to 3%). In contrast, [THg] in littoral macroinvertebrates showed lower values (0.3 to 1.8 μg g{sup −1} DW). Juvenile and small fish species feeding upon plankton had higher [THg] (0.2 to 8 μg g{sup −1} muscle DW) compared to large piscivore fish species (0.1 to 1.6 μg g{sup −1} muscle DW). Selenium concentrations exhibited a much narrower variation range than THg in the food web, varying from 0.5 to 2.7 μg g{sup −1} DW. Molar Se:Hg ratios exceeded 1 for the majority of organisms in both basins, with most ratios exceeding 10. Using stable nitrogen isotopes as indicator of trophic level, no significant correlations were found with [THg], [Se] or Se:Hg. The apparent lack of biomagnification trends was attributed to elevated [THg] in plankton in the inorganic form mostly, as well as the possibility of consistent Se supply reducing the biomagnification in the food web of the organic portion of THg. Highlights: • Mercury was studied in the food web of Lake Moreno, Nahuel Huapi National Park. • Mercury trophic transfer was assessed by nitrogen stable isotope (δ{sup 15}N) analysis. • Selenium was determined showing consistent source in pelagic and littoral organisms. • High mercury concentrations, mostly inorganic, were determined in plankton. • No mercury biomagnification was observed in Lake Moreno food web.

  14. Enhancing food engineering education with interactive web-based simulations

    Directory of Open Access Journals (Sweden)

    Alexandros Koulouris

    2015-04-01

    Full Text Available In the traditional deductive approach in teaching any engineering topic, teachers would first expose students to the derivation of the equations that govern the behavior of a physical system and then demonstrate the use of equations through a limited number of textbook examples. This methodology, however, is rarely adequate to unmask the cause-effect and quantitative relationships between the system variables that the equations embody. Web-based simulation, which is the integration of simulation and internet technologies, has the potential to enhance the learning experience by offering an interactive and easily accessible platform for quick and effortless experimentation with physical phenomena.This paper presents the design and development of a web-based platform for teaching basic food engineering phenomena to food technology students. The platform contains a variety of modules (“virtual experiments” covering the topics of mass and energy balances, fluid mechanics and heat transfer. In this paper, the design and development of three modules for mass balances and heat transfer is presented. Each webpage representing an educational module has the following features: visualization of the studied phenomenon through graphs, charts or videos, computation through a mathematical model and experimentation.  The student is allowed to edit key parameters of the phenomenon and observe the effect of these changes on the outputs. Experimentation can be done in a free or guided fashion with a set of prefabricated examples that students can run and self-test their knowledge by answering multiple-choice questions.

  15. The world wide web: exploring a new advertising environment.

    Science.gov (United States)

    Johnson, C R; Neath, I

    1999-01-01

    The World Wide Web currently boasts millions of users in the United States alone and is likely to continue to expand both as a marketplace and as an advertising environment. Three experiments explored advertising in the Web environment, in particular memory for ads as they appear in everyday use across the Web. Experiments 1 and 2 examined the effect of advertising repetition on the retention of familiar and less familiar brand names, respectively. Experiment 1 demonstrated that repetition of a banner ad within multiple web pages can improve recall of familiar brand names, and Experiment 2 demonstrated that repetition can improve recognition of less familiar brand names. Experiment 3 directly compared the retention of familiar and less familiar brand names that were promoted by static and dynamic ads and demonstrated that the use of dynamic advertising can increase brand name recall, though only for familiar brand names. This study also demonstrated that, in the Web environment, much as in other advertising environments, familiar brand names possess a mnemonic advantage not possessed by less familiar brand names. Finally, data regarding Web usage gathered from all experiments confirm reports that Web usage among males tends to exceed that among females.

  16. Carbon flows through a benthic food web: Integrating biomass, isotope and tracer data

    NARCIS (Netherlands)

    Van Oevelen, D.; Soetaert, K.E.R.; Middelburg, J.J.; Herman, P.M.J.; Moodley, L.; Hamels, I.; Moens, T.; Heip, C.H.R.

    2006-01-01

    The herbivorous, detrital and microbial pathways are major components of marine food webs. Although it is commonly recognized that these pathways can be linked in several ways, elucidating carbon transfers between or within these pathways remains a challenge. Intertidal flat communities are driven

  17. Productivity and linkages of the food web of the southern region of the western Antarctic Peninsula continental shelf

    Science.gov (United States)

    Ballerini, Tosca; Hofmann, Eileen E.; Ainley, David G.; Daly, Kendra L.; Marrari, Marina; Ribic, Christine A.; Smith, Walker O.; Steele, John H.

    2014-01-01

    The productivity and linkages in the food web of the southern region of the west Antarctic Peninsula continental shelf were investigated using a multi-trophic level mass balance model. Data collected during the Southern Ocean Global Ocean Ecosystem Dynamics field program were combined with data from the literature on the abundance and diet composition of zooplankton, fish, seabirds and marine mammals to calculate energy flows in the food web and to infer the overall food web structure at the annual level. Sensitivity analyses investigated the effects of variability in growth and biomass of Antarctic krill (Euphausia superba) and in the biomass of Antarctic krill predators on the structure and energy fluxes in the food web. Scenario simulations provided insights into the potential responses of the food web to a reduced contribution of large phytoplankton (diatom) production to total primary production, and to reduced consumption of primary production by Antarctic krill and mesozooplankton coincident with increased consumption by microzooplankton and salps. Model-derived estimates of primary production were 187–207 g C m−2 y−1, which are consistent with observed values (47–351 g C m−2 y−1). Simulations showed that Antarctic krill provide the majority of energy needed to sustain seabird and marine mammal production, thereby exerting a bottom-up control on higher trophic level predators. Energy transfer to top predators via mesozooplanton was a less efficient pathway, and salps were a production loss pathway because little of the primary production they consumed was passed to higher trophic levels. Increased predominance of small phytoplankton (nanoflagellates and cryptophytes) reduced the production of Antarctic krill and of its predators, including seabirds and seals.

  18. Impact of non-native terrestrial mammals on the structure of the terrestrial mammal food web of Newfoundland, Canada.

    Directory of Open Access Journals (Sweden)

    Justin S Strong

    Full Text Available The island of Newfoundland is unique because it has as many non-native terrestrial mammals as native ones. The impacts of non-native species on native flora and fauna can be profound and invasive species have been identified as one of the primary drivers of species extinction. Few studies, however, have investigated the effects of a non-native species assemblage on community and ecosystem properties. We reviewed the literature to build the first terrestrial mammal food web for the island of Newfoundland and then used network analyses to investigate how the timing of introductions and trophic position of non-native species has affected the structure of the terrestrial mammal food web in Newfoundland. The first non-native mammals (house mouse and brown rat became established in Newfoundland with human settlement in the late 15th and early 16th centuries. Coyotes and southern red-backed voles are the most recent mammals to establish themselves on the island in 1985 and 1998, respectively. The fraction of intermediate species increased with the addition of non-native mammals over time whereas the fraction of basal and top species declined over time. This increase in intermediate species mediated by non-native species arrivals led to an overall increase in the terrestrial mammal food web connectance and generality (i.e. mean number of prey per predator. This diverse prey base and sources of carrion may have facilitated the natural establishment of coyotes on the island. Also, there is some evidence that the introduction of non-native prey species such as the southern red-backed vole has contributed to the recovery of the threatened American marten. Long-term monitoring of the food web is required to understand and predict the impacts of the diverse novel interactions that are developing in the terrestrial mammal food web of Newfoundland.

  19. Community cascades in a marine pelagic food web controlled by the non-visual apex predator Mnemiopsis leidyi

    DEFF Research Database (Denmark)

    Tiselius, Peter; Møller, Lene Friis

    2017-01-01

    Trophic cascades are a ubiquitous feature of many terrestrial and fresh-water food webs, but have been difficult to demonstrate in marine systems with multispecies trophic levels. Here we describe significant trophic cascades in an open coastal planktonic ecosystem exposed to an introduced top...... predator. The ctenophore Mnemiopsis leidyi was monitored for an 8-year period concurrent with measures of the food web structure of the plankton and strong trophic cascades were evident. In the 5 years when M. leidyi were found, their target prey (grazing copepods) were reduced 5-fold and the primary...

  20. Methylmercury bioaccumulation in stream food webs declines with increasing primary production

    Science.gov (United States)

    Walters, David; D.F. Raikow,; C.R. Hammerschmidt,; M.G. Mehling,; A. Kovach,; J.T. Oris,

    2015-01-01

    Opposing hypotheses posit that increasing primary productivity should result in either greater or lesser contaminant accumulation in stream food webs. We conducted an experiment to evaluate primary productivity effects on MeHg accumulation in stream consumers. We varied light for 16 artificial streams creating a productivity gradient (oxygen production =0.048–0.71 mg O2 L–1 d–1) among streams. Two-level food webs were established consisting of phytoplankton/filter feeding clam, periphyton/grazing snail, and leaves/shredding amphipod (Hyalella azteca). Phytoplankton and periphyton biomass, along with MeHg removal from the water column, increased significantly with productivity, but MeHg concentrations in these primary producers declined. Methylmercury concentrations in clams and snails also declined with productivity, and consumer concentrations were strongly correlated with MeHg concentrations in primary producers. Heterotroph biomass on leaves, MeHg in leaves, and MeHg in Hyalella were unrelated to stream productivity. Our results support the hypothesis that contaminant bioaccumulation declines with stream primary production via the mechanism of bloom dilution (MeHg burden per cell decreases in algal blooms), extending patterns of contaminant accumulation documented in lakes to lotic systems.

  1. Effects of climate on size structure and functioning of aquatic food webs

    NARCIS (Netherlands)

    Lacerot, G.

    2010-01-01

    In aquatic food webs, the role of body size is notoriously strong. It is also well known that temperature has an effect on body size. For instance, Bergmann’s rule states that body size increases from warm to cold climates. This thesis addresses the question how climate shapes the size structure of

  2. Dynamics of Consumer Response to Food Contamination: The 2007 Peanut Butter Recall

    OpenAIRE

    Bakhtavoryan, Rafael; Capps, Oral, Jr.; Salin, Victoria

    2014-01-01

    We investigate the foodborne illness outbreak affecting a national brand of peanut butter to determine how demand for the product category was affected. The illness outbreak coincided with growth in the quantity demanded for the peanut butter category. The negative impact on the category associated with the initiation of the product recall was significant and dissipated over time. The recovery of the product category after the recall indicates that the information was correctly targeted and a...

  3. Density- and trait-mediated top-down effects modify bottom-up control of a highly endemic tropical aquatic food web

    Science.gov (United States)

    C. M. Dalton; A. Mokiao-Lee; T. S. Sakihara; M. G. Weber; C. A. Roco; Z. Han; B. Dudley; R. A. MacKenzie; N. G. Hairston Jr.

    2013-01-01

    Benthic invertebrates mediate bottom–up and top–down influences in aquatic food webs, and changes in the abundance or traits of invertebrates can alter the strength of top–down effects. Studies assessing the role of invertebrate abundance and behavior as controls on food web structure are rare at the whole ecosystem scale. Here we use a comparative approach to...

  4. A thermodynamic perspective on food webs: Quantifying entropy production within detrital-based ecosystems

    NARCIS (Netherlands)

    Meysman, F.J.R.; Bruers, S.

    2007-01-01

    Because ecosystems fit so nicely the framework of a “dissipative system”, a better integration of thermodynamic and ecological perspectives could benefit the quantitative analysis of ecosystems. One obstacle is that traditional food web models are solely based upon the principles of mass and energy

  5. Tracing organophosphorus and brominated flame retardants and plasticizers in an estuarine food web

    NARCIS (Netherlands)

    Brandsma, S.H.; Leonards, P.E.G.; Leslie, H.A.; de Boer, J.

    2015-01-01

    Nine organophosphorus flame retardants (PFRs) were detected in a pelagic and benthic food web of the Western Scheldt estuary, The Netherlands. Concentrations of several PFRs were an order of magnitude higher than those of the brominated flame retardants (BFRs). However, the detection frequency of

  6. Microbial food web dynamics along a soil chronosequence of a glacier forefield

    Directory of Open Access Journals (Sweden)

    J. Esperschütz

    2011-11-01

    Full Text Available Microbial food webs are critical for efficient nutrient turnover providing the basis for functional and stable ecosystems. However, the successional development of such microbial food webs and their role in "young" ecosystems is unclear. Due to a continuous glacier retreat since the middle of the 19th century, glacier forefields have expanded offering an excellent opportunity to study food web dynamics in soils at different developmental stages. In the present study, litter degradation and the corresponding C fluxes into microbial communities were investigated along the forefield of the Damma glacier (Switzerland. 13C-enriched litter of the pioneering plant Leucanthemopsis alpina (L. Heywood was incorporated into the soil at sites that have been free from ice for approximately 10, 60, 100 and more than 700 years. The structure and function of microbial communities were identified by 13C analysis of phospholipid fatty acids (PLFA and phospholipid ether lipids (PLEL. Results showed increasing microbial diversity and biomass, and enhanced proliferation of bacterial groups as ecosystem development progressed. Initially, litter decomposition proceeded faster at the more developed sites, but at the end of the experiment loss of litter mass was similar at all sites, once the more easily-degradable litter fraction was processed. As a result incorporation of 13C into microbial biomass was more evident during the first weeks of litter decomposition. 13C enrichments of both PLEL and PLFA biomarkers following litter incorporation were observed at all sites, suggesting similar microbial foodwebs at all stages of soil development. Nonetheless, the contribution of bacteria, especially actinomycetes to litter turnover became more pronounced as soil age increased in detriment of archaea, fungi and protozoa, more prominent in recently deglaciated terrain.

  7. Fungal-to-bacterial dominance of soil detrital food-webs: Consequences for biogeochemistry

    Science.gov (United States)

    Rousk, Johannes; Frey, Serita

    2015-04-01

    Resolving fungal and bacterial groups within the microbial decomposer community is thought to capture disparate microbial life strategies, associating bacteria with an r-selected strategy for carbon (C) and nutrient use, and fungi with a K-selected strategy. Additionally, food-web models have established a widely held belief that the bacterial decomposer pathway in soil supports high turnover rates of easily available substrates, while the slower fungal pathway supports the decomposition of more complex organic material, thus characterising the biogeochemistry of the ecosystem. Three field-experiments to generate gradients of SOC-quality were assessed. (1) the Detritus Input, Removal, and Trenching - DIRT - experiment in a temperate forest in mixed hardwood stands at Harvard Forest LTER, US. There, experimentally adjusted litter input and root input had affected the SOC quality during 23 years. (2) field-application of 14-C labelled glucose to grassland soils, sampled over the course of 13 months to generate an age-gradient of SOM (1 day - 13 months). (3) The Park Grass Experiment at Rothamsted, UK, where 150-years continuous N-fertilisation (0, 50, 100, 150 kg N ha-1 y-1) has affected the quality of SOM in grassland soils. A combination of carbon stable and radio isotope studies, fungal and bacterial growth and biomass measurements, and C and N mineralisation (15N pool dilution) assays were used to investigate how SOC-quality influenced fungal and bacterial food-web pathways and the implications this had for C and nutrient turnover. There was no support that decomposer food-webs dominated by bacteria support high turnover rates of easily available substrates, while slower fungal-dominated decomposition pathways support the decomposition of more complex organic material. Rather, an association between high quality SOC and fungi emerges from the results. This suggests that we need to revise our basic understanding for soil microbial communities and the processes

  8. Terrestrial contributions to the aquatic food web in the middle Yangtze River.

    Science.gov (United States)

    Wang, Jianzhu; Gu, Binhe; Huang, Jianhui; Han, Xingguo; Lin, Guanghui; Zheng, Fawen; Li, Yuncong

    2014-01-01

    Understanding the carbon sources supporting aquatic consumers in large rivers is essential for the protection of ecological integrity and for wildlife management. The relative importance of terrestrial and algal carbon to the aquatic food webs is still under intensive debate. The Yangtze River is the largest river in China and the third longest river in the world. The completion of the Three Gorges Dam (TGD) in 2003 has significantly altered the hydrological regime of the middle Yangtze River, but its immediate impact on carbon sources supporting the river food web is unknown. In this study, potential production sources from riparian and the main river channel, and selected aquatic consumers (invertebrates and fish) at an upstream constricted-channel site (Luoqi), a midstream estuarine site (Huanghua) and a near dam limnetic site (Maoping) of the TGD were collected for stable isotope (δ13C and δ15N) and IsoSource analyses. Model estimates indicated that terrestrial plants were the dominant carbon sources supporting the consumer taxa at the three study sites. Algal production appeared to play a supplemental role in supporting consumer production. The contribution from C4 plants was more important than that of C3 plants at the upstream site while C3 plants were the more important carbon source to the consumers at the two impacted sites (Huanghua and Maoping), particularly at the midstream site. There was no trend of increase in the contribution of autochthonous production from the upstream to the downstream sites as the flow rate decreased dramatically along the main river channel due to the construction of TGD. Our findings, along with recent studies in rivers and lakes, are contradictory to studies that demonstrate the importance of algal carbon in the aquatic food web. Differences in system geomorphology, hydrology, habitat heterogeneity, and land use may account for these contradictory findings reported in various studies.

  9. Flows of dioxins and furans in coastal food webs: inverse modeling, sensitivity analysis, and applications of linear system theory.

    Science.gov (United States)

    Saloranta, Tuomo M; Andersen, Tom; Naes, Kristoffer

    2006-01-01

    Rate constant bioaccumulation models are applied to simulate the flow of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the coastal marine food web of Frierfjorden, a contaminated fjord in southern Norway. We apply two different ways to parameterize the rate constants in the model, global sensitivity analysis of the models using Extended Fourier Amplitude Sensitivity Test (Extended FAST) method, as well as results from general linear system theory, in order to obtain a more thorough insight to the system's behavior and to the flow pathways of the PCDD/Fs. We calibrate our models against observed body concentrations of PCDD/Fs in the food web of Frierfjorden. Differences between the predictions from the two models (using the same forcing and parameter values) are of the same magnitude as their individual deviations from observations, and the models can be said to perform about equally well in our case. Sensitivity analysis indicates that the success or failure of the models in predicting the PCDD/F concentrations in the food web organisms highly depends on the adequate estimation of the truly dissolved concentrations in water and sediment pore water. We discuss the pros and cons of such models in understanding and estimating the present and future concentrations and bioaccumulation of persistent organic pollutants in aquatic food webs.

  10. Contamination of an arctic terrestrial food web with marine-derived persistent organic pollutants transported by breeding seabirds

    International Nuclear Information System (INIS)

    Choy, Emily S.; Kimpe, Linda E.; Mallory, Mark L.; Smol, John P.; Blais, Jules M.

    2010-01-01

    At Cape Vera, Devon Island (Nunavut, Canada), a colony of northern fulmars (Fulmarus glacialis) concentrates and releases contaminants through their guano to the environment. We determined whether persistent organic pollutants (POPs) from seabirds were transferred to coastal food webs. Snow buntings (Plectrophenax nivalis) were the most contaminated species, with ΣPCB and ΣDDT (mean: 168, 106 ng/g ww) concentrations surpassing environmental guidelines for protecting wildlife. When examined collectively, PCB congeners and DDT in jewel lichen (Xanthoria elegans) were lower in samples taken farther from the seabird colony, and increased with increasing δ 15 N values. However, only concentrations of p'p-DDE:ΣDDT and PCB-95 were significantly correlated inversely with distance from the seabird cliffs. Linkages between marine-derived POPs and their concentrations in terrestrial mammals were less clear. Our study provides novel contaminant data for these species and supports biovector transport as a source of organic contaminants to certain components of the terrestrial food web. - This study provides evidence of contaminant transport by seabirds to a coastal Arctic food web.

  11. Contamination of an arctic terrestrial food web with marine-derived persistent organic pollutants transported by breeding seabirds

    Energy Technology Data Exchange (ETDEWEB)

    Choy, Emily S., E-mail: echoy087@uottawa.c [Program for Chemical and Environmental Toxicology, Department of Biology, University of Ottawa, Ottawa, ON, K1N 6N5 (Canada); Kimpe, Linda E., E-mail: linda.kimpe@uottawa.c [Program for Chemical and Environmental Toxicology, Department of Biology, University of Ottawa, Ottawa, ON, K1N 6N5 (Canada); Mallory, Mark L., E-mail: mark.mallory@ec.gc.c [Canadian Wildlife Service, Environment Canada, Iqaluit, NU, X0A 0H0 (Canada); Smol, John P., E-mail: smolj@queensu.c [Paleoecological Environmental Assessment and Research Lab (PEARL), Department of Biology, Queen' s University, Kingston, ON, K7L 3N6 (Canada); Blais, Jules M., E-mail: jules.blais@uottawa.c [Program for Chemical and Environmental Toxicology, Department of Biology, University of Ottawa, Ottawa, ON, K1N 6N5 (Canada)

    2010-11-15

    At Cape Vera, Devon Island (Nunavut, Canada), a colony of northern fulmars (Fulmarus glacialis) concentrates and releases contaminants through their guano to the environment. We determined whether persistent organic pollutants (POPs) from seabirds were transferred to coastal food webs. Snow buntings (Plectrophenax nivalis) were the most contaminated species, with {Sigma}PCB and {Sigma}DDT (mean: 168, 106 ng/g ww) concentrations surpassing environmental guidelines for protecting wildlife. When examined collectively, PCB congeners and DDT in jewel lichen (Xanthoria elegans) were lower in samples taken farther from the seabird colony, and increased with increasing {delta}{sup 15}N values. However, only concentrations of p'p-DDE:{Sigma}DDT and PCB-95 were significantly correlated inversely with distance from the seabird cliffs. Linkages between marine-derived POPs and their concentrations in terrestrial mammals were less clear. Our study provides novel contaminant data for these species and supports biovector transport as a source of organic contaminants to certain components of the terrestrial food web. - This study provides evidence of contaminant transport by seabirds to a coastal Arctic food web.

  12. Trophodynamics of Organic Pollutants in Pelagic and Benthic Food Webs of Lake Dianchi: Importance of Ingested Sediment As Uptake Route.

    Science.gov (United States)

    Fan, Senrong; Wang, Beili; Liu, Hang; Gao, Shixiong; Li, Tong; Wang, Shuran; Liu, Yong; Liu, Xueqin; Wan, Yi

    2017-12-19

    Habitat is of great importance in determining the trophic transfer of pollutants in freshwater ecosystems; however, the major factors influencing chemical trophodynamics in pelagic and benthic food webs remain unclear. This study investigated the levels of p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), polycyclic aromatic hydrocarbons (PAHs), and substituted PAHs (s-PAHs) in 2 plankton species, 6 invertebrate species, and 10 fish species collected from Lake Dianchi in southern China. Relatively high concentrations of PAHs and s-PAHs were detected with total concentrations of 11.4-1400 ng/g wet weight (ww) and 5.3-115 ng/g ww, respectively. Stable isotope analysis and stomach content analysis were applied to quantitatively determine the trophic level of individual organisms and discriminate between pelagic and benthic pathways, and the trophodynamics of the detected compounds in the two food webs were assessed. P,p'-DDE was found to exhibit relatively higher trophic magnification rate in the pelagic food web than in the benthic food web. In contrast, PAHs and s-PAHs exhibited greater dilution rates along the trophic levels in the pelagic food web. The lower species differences of pollutants accumulated in benthic organisms compared to pelagic organisms is attributable to extra uptake via ingested sediment in benthos. The average uptake proportions of PAHs and s-PAHs via ingested sediment in benthic biotas were estimated to be 31-77%, and that of p,p'-DDE was 46%. The uptake routes are of importance for assessing the trophic magnification potentials of organic pollutants, especially in eutrophic freshwater ecosystems.

  13. Changes in food web structure and ecosystem functioning of a large, shallow Chinese lake during the 1950s, 1980s and 2000s

    NARCIS (Netherlands)

    Kong, Xiangzhen; He, Wei; Liu, Wenxiu; Yang, Bin; Xu, Fuliu; Jørgensen, Sven Erik; Mooij, W.M.

    2016-01-01

    Food web structure dynamics and ecosystem functioning are strongly linked, and both are indispensable in evaluating ecosystem development in lakes under multiple anthropogenic stressors. However, model-based approaches concerning the changes in food web structure and ecosystem functioning in a

  14. Polycyclic aromatic hydrocarbons alter the structure of oceanic and oligotrophic microbial food webs

    KAUST Repository

    Cerezo, Maria Isabel; Agusti, Susana

    2015-01-01

    One way organic pollutants reach remote oceanic regions is by atmospheric transport. During the Malaspina-2010 expedition, across the Atlantic, Indian, and Pacific Oceans, we analyzed the polycyclic aromatic hydrocarbon (PAH) effects on oceanic microbial food webs. We performed perturbation experiments adding PAHs to classic dilution experiments. The phytoplankton growth rates were reduced by more than 5 times, being Prochlorococcus spp. the most affected. 62% of the experiments showed a reduction in the grazing rates due to the presence of PAHs. For the remaining experiments, grazing usually increased likely due to cascading effects. We identified changes in the slope of the relation between the growth rate and the dilution fraction induced by the pollutants, moving from no grazing to V-shape, or to negative slope, indicative of grazing increase by cascade effects and alterations of the grazers' activity structure. Our perturbation experiments indicate that PAHs could influence the structure oceanic food-webs structure.

  15. Polycyclic aromatic hydrocarbons alter the structure of oceanic and oligotrophic microbial food webs

    KAUST Repository

    Cerezo, Maria Isabel

    2015-11-01

    One way organic pollutants reach remote oceanic regions is by atmospheric transport. During the Malaspina-2010 expedition, across the Atlantic, Indian, and Pacific Oceans, we analyzed the polycyclic aromatic hydrocarbon (PAH) effects on oceanic microbial food webs. We performed perturbation experiments adding PAHs to classic dilution experiments. The phytoplankton growth rates were reduced by more than 5 times, being Prochlorococcus spp. the most affected. 62% of the experiments showed a reduction in the grazing rates due to the presence of PAHs. For the remaining experiments, grazing usually increased likely due to cascading effects. We identified changes in the slope of the relation between the growth rate and the dilution fraction induced by the pollutants, moving from no grazing to V-shape, or to negative slope, indicative of grazing increase by cascade effects and alterations of the grazers\\' activity structure. Our perturbation experiments indicate that PAHs could influence the structure oceanic food-webs structure.

  16. The role of a water bug, Sigara striata, in freshwater food webs

    Czech Academy of Sciences Publication Activity Database

    Klečka, Jan

    2014-01-01

    Roč. 2, č. 1 (2014), e389 ISSN 2167-8359 Grant - others:Student Grant Agency of the Faculty of Biological Sciences, University of South Bohemia(CZ) SGA 2008 Institutional support: RVO:60077344 Keywords : predation * predator-prey interactions * food webs Subject RIV: EH - Ecology, Behaviour Impact factor: 2.112, year: 2014 https://peerj.com/articles/389.pdf

  17. Global change-driven effects on dissolved organic matter composition: Implications for food webs of northern lakes.

    Science.gov (United States)

    Creed, Irena F; Bergström, Ann-Kristin; Trick, Charles G; Grimm, Nancy B; Hessen, Dag O; Karlsson, Jan; Kidd, Karen A; Kritzberg, Emma; McKnight, Diane M; Freeman, Erika C; Senar, Oscar E; Andersson, Agneta; Ask, Jenny; Berggren, Martin; Cherif, Mehdi; Giesler, Reiner; Hotchkiss, Erin R; Kortelainen, Pirkko; Palta, Monica M; Vrede, Tobias; Weyhenmeyer, Gesa A

    2018-03-15

    Northern ecosystems are experiencing some of the most dramatic impacts of global change on Earth. Rising temperatures, hydrological intensification, changes in atmospheric acid deposition and associated acidification recovery, and changes in vegetative cover are resulting in fundamental changes in terrestrial-aquatic biogeochemical linkages. The effects of global change are readily observed in alterations in the supply of dissolved organic matter (DOM)-the messenger between terrestrial and lake ecosystems-with potentially profound effects on the structure and function of lakes. Northern terrestrial ecosystems contain substantial stores of organic matter and filter or funnel DOM, affecting the timing and magnitude of DOM delivery to surface waters. This terrestrial DOM is processed in streams, rivers, and lakes, ultimately shifting its composition, stoichiometry, and bioavailability. Here, we explore the potential consequences of these global change-driven effects for lake food webs at northern latitudes. Notably, we provide evidence that increased allochthonous DOM supply to lakes is overwhelming increased autochthonous DOM supply that potentially results from earlier ice-out and a longer growing season. Furthermore, we assess the potential implications of this shift for the nutritional quality of autotrophs in terms of their stoichiometry, fatty acid composition, toxin production, and methylmercury concentration, and therefore, contaminant transfer through the food web. We conclude that global change in northern regions leads not only to reduced primary productivity but also to nutritionally poorer lake food webs, with discernible consequences for the trophic web to fish and humans. © 2018 John Wiley & Sons Ltd.

  18. Musculoskeletal allograft risks and recalls in the United States.

    Science.gov (United States)

    Mroz, Thomas E; Joyce, Michael J; Steinmetz, Michael P; Lieberman, Isador H; Wang, Jeffrey C

    2008-10-01

    There have been several improvements to the US tissue banking industry over the past decade. Tissue banks had limited active government regulation until 1993, at which time the US Food and Drug Administration began regulatory oversight because of reports of disease transmission from allograft tissues. Reports in recent years of disease transmission associated with the use of allografts have further raised concerns about the safety of such implants. A retrospective review of allograft recall data was performed to analyze allograft recall by tissue type, reason, and year during the period from January 1994 to June 30, 2007. During the study period, more than 96.5% of all allograft tissues recalled were musculoskeletal. The reasons underlying recent musculoskeletal tissue recalls include insufficient or improper donor evaluation, contamination, recipient infection, and positive serologic tests. Infectious disease transmission following allograft implantation may occur if potential donors are not adequately evaluated or screened serologically during the prerecovery phase and if the implant is not sterilized before implantation.

  19. Consumer Response to Web Sites and Their Influence on Advertising Effectiveness.

    Science.gov (United States)

    Goldsmith, Ronald E.; Lafferty, Barbara A.

    2002-01-01

    Describes a study of undergraduates that tested four hypotheses regarding the effects of viewing Web sites on Internet advertising. Highlights include attitudes toward ads in marketing communications and advertising research; recalling brand names seen on the Internet; perceived advantages and disadvantages of online advertising; and recalling ads…

  20. Effects of Working Memory Capacity and Domain Knowledge on Recall for Grocery Prices.

    Science.gov (United States)

    Bermingham, Douglas; Gardner, Michael K; Woltz, Dan J

    2016-01-01

    Hambrick and Engle (2002) proposed 3 models of how domain knowledge and working memory capacity may work together to influence episodic memory: a "rich-get-richer" model, a "building blocks" model, and a "compensatory" model. Their results supported the rich-get-richer model, although later work by Hambrick and Oswald (2005) found support for a building blocks model. We investigated the effects of domain knowledge and working memory on recall of studied grocery prices. Working memory was measured with 3 simple span tasks. A contrast of realistic versus fictitious foods in the episodic memory task served as our manipulation of domain knowledge, because participants could not have domain knowledge of fictitious food prices. There was a strong effect for domain knowledge (realistic food-price pairs were easier to remember) and a moderate effect for working memory capacity (higher working memory capacity produced better recall). Furthermore, the interaction between domain knowledge and working memory produced a small but significant interaction in 1 measure of price recall. This supported the compensatory model and stands in contrast to previous research.

  1. Cross-ecosystem impacts of stream pollution reduce resource and contaminant flux to riparian food webs

    Science.gov (United States)

    Kraus, Johanna M.; Schmidt, Travis S.; Walters, David; Wanty, Richard B.; Zuellig, Robert E.; Wolf, Ruth E.

    2014-01-01

    The effects of aquatic contaminants are propagated across ecosystem boundaries by aquatic insects that export resources and contaminants to terrestrial food webs; however, the mechanisms driving these effects are poorly understood. We examined how emergence, contaminant concentration, and total contaminant flux by adult aquatic insects changed over a gradient of bioavailable metals in streams and how these changes affected riparian web-building spiders. Insect emergence decreased 97% over the metal gradient, whereas metal concentrations in adult insects changed relatively little. As a result, total metal exported by insects (flux) was lowest at the most contaminated streams, declining 96% among sites. Spiders were affected by the decrease in prey biomass, but not by metal exposure or metal flux to land in aquatic prey. Aquatic insects are increasingly thought to increase exposure of terrestrial consumers to aquatic contaminants, but stream metals reduce contaminant flux to riparian consumers by strongly impacting the resource linkage. Our results demonstrate the importance of understanding the contaminant-specific effects of aquatic pollutants on adult insect emergence and contaminant accumulation in adults to predict impacts on terrestrial food webs.

  2. Effects of light reduction on food webs and associated ecosystem services of Yaquina Bay

    Science.gov (United States)

    Reduced water clarity can affect estuarine primary production but little is known of its subsequent effects to consumer guilds or ecosystem services. We investigated those effects using inverse analysis of modeled food webs of the lower (polyhaline) and upper (mesohaline) reache...

  3. Changes in the Lake Michigan food web following dreissenid mussel invasions: A synthesis

    Science.gov (United States)

    Madenjian, Charles P.; Bunnell, David B.; Warner, David M.; Pothoven, Steven A.; Fahnenstiel, Gary L.; Nalepa, Thomas F.; Vanderploeg, Henry A.; Tsehaye, Iyob; Claramunt, Randall M.; Clark, Richard D

    2015-01-01

    Using various available time series for Lake Michigan, we examined changes in the Lake Michigan food web following the dreissenid mussel invasions and identified those changes most likely attributable to these invasions, thereby providing a synthesis. Expansion of the quagga mussel (Dreissena rostriformis bugensis) population into deeper waters, which began around 2004, appeared to have a substantial predatory effect on both phytoplankton abundance and primary production, with annual primary production in offshore (> 50 m deep) waters being reduced by about 35% by 2007. Primary production likely decreased in nearshore waters as well, primarily due to predatory effects exerted by the quagga mussel expansion. The drastic decline inDiporeia abundance in Lake Michigan during the 1990s and 2000s has been attributed to dreissenid mussel effects, but the exact mechanism by which the mussels were negatively affecting Diporeia abundance remains unknown. In turn, decreased Diporeiaabundance was associated with reduced condition, growth, and/or energy density in alewife (Alosa pseudoharengus), lake whitefish (Coregonus clupeaformis), deepwater sculpin (Myoxocephalus thompsonii), and bloater (Coregonus hoyi). However, lake-wide biomass of salmonines, top predators in the food web, remained high during the 2000s, and consumption of alewives by salmonines actually increased between the 1980–1995 and 1996–2011 time periods. Moreover, abundance of the lake whitefish population, which supports Lake Michigan's most valuable commercial fishery, remained at historically high levels during the 2000s. Apparently, counterbalancing mechanisms operating within the complex Lake Michigan food web have enabled salmonines and lake whitefish to retain relatively high abundances despite reduced primary production.

  4. Trophic transfer of persistent organochlorine contaminants (OCs) within an Arctic marine food web from the southern Beaufort-Chukchi Seas

    International Nuclear Information System (INIS)

    Hoekstra, P.F.; O'Hara, T.M.; Fisk, A.T.; Borgaa, K.; Solomon, K.R.; Muir, D.C.G.

    2003-01-01

    The trophic status and biomagnification of persistent OCs within the near-shore Beaufort-Chukchi Seas food web from Barrow, AK is discussed. - Stable isotope values (δ 13 C, δ 15 N) and concentrations of persistent organochlorine contaminants (OCs) were determined to evaluate the near-shore marine trophic status of biota and biomagnification of OCs from the southern Beaufort-Chukchi Seas (1999-2000) near Barrow, AK. The biota examined included zooplankton (Calanus spp.), fish species such as arctic cod (Boreogadus saida), arctic char (Salvelinus alpinus), pink salmon (Oncorhynchus gorbuscha), and fourhorn sculpin (Myoxocephalus quadricornis), along with marine mammals, including bowhead whales (Balaena mysticetus), beluga whales (Delphinapterus leucas), ringed seals (Phoca hispida) and bearded seals (Erignathus barbatus). The isotopically derived trophic position of biota from the Beaufort-Chukchi Seas marine food web, avian fauna excluded, is similar to other coastal food webs in the Arctic. Concentrations of OCs in marine mammals were significantly greater than in fish and corresponded with determined trophic level. In general, OCs with the greatest food web magnification factors (FWMFs) were those either formed due to biotransformation (e.g. p,p'-DDE, oxychlordane) or considered recalcitrant (e.g. β-HCH, 2,4,5-Cl substituted PCBs) in most biota, whereas concentrations of OCs that are considered to be readily eliminated (e.g. γ-HCH) did not correlate with trophic level. Differences in physical-chemical properties of OCs, feeding strategy and possible biotransformation were reflected in the variable biomagnification between fish and marine mammals. The FWMFs in the Beaufort-Chukchi Seas region were consistent with reported values in the Canadian Arctic and temperate food webs, but were statistically different than FWMFs from the Barents and White Seas, indicating that the spatial variability of OC contamination in top-level marine Arctic predators is

  5. Children's food preferences: effects of weight status, food type, branding and television food advertisements (commercials).

    Science.gov (United States)

    Halford, Jason C G; Boyland, Emma J; Cooper, Gillian D; Dovey, Terence M; Smith, Cerise J; Williams, Nicola; Lawton, Clare L; Blundell, John E

    2008-01-01

    OBJECTIVE. To investigate the effects of weight status, food type and exposure to food and non-food advertisements on children's preference for branded and non-branded foods. DESIGN. A within-subjects, counterbalanced design with control (toy advertisement) and experimental (food advertisement) conditions. Subjects. A total of 37 school students (age: 11-13 years; weight status: 24 lean, 10 overweight, 3 obese). Measurements. Advertisement recall list, two food preference measures; the Leeds Food Preference Measure (LFPM), the Adapted Food Preference Measure (AFPM) and a food choice measure; the Leeds Forced-choice Test (LFCT). RESULTS. Normal weight children selected more branded and non-branded food items after exposure to food advertisements than in the control (toy advertisement) condition. Obese and overweight children showed a greater preference for branded foods than normal weight children per se, and also in this group only, there was a significant correlation between food advertisement recall and the total number of food items chosen in the experimental (food advertisement) condition. CONCLUSION. Exposure to food advertisements increased the preference for branded food items in the normal weight children. This suggests that television food advertisement exposure can produce the same 'obesigenic' food preference response found in overweight and obese children in their normal weight counterparts.

  6. Trophic state changes can affect the importance of methane-derived carbon in aquatic food webs.

    Science.gov (United States)

    Schilder, Jos; van Hardenbroek, Maarten; Bodelier, Paul; Kirilova, Emiliya P; Leuenberger, Markus; Lotter, André F; Heiri, Oliver

    2017-06-28

    Methane-derived carbon, incorporated by methane-oxidizing bacteria, has been identified as a significant source of carbon in food webs of many lakes. By measuring the stable carbon isotopic composition (δ 13 C values) of particulate organic matter, Chironomidae and Daphnia spp. and their resting eggs (ephippia), we show that methane-derived carbon presently plays a relevant role in the food web of hypertrophic Lake De Waay, The Netherlands. Sediment geochemistry, diatom analyses and δ 13 C measurements of chironomid and Daphnia remains in the lake sediments indicate that oligotrophication and re-eutrophication of the lake during the twentieth century had a strong impact on in-lake oxygen availability. This, in turn, influenced the relevance of methane-derived carbon in the diet of aquatic invertebrates. Our results show that, contrary to expectations, methane-derived relative to photosynthetically produced organic carbon became more relevant for at least some invertebrates during periods with higher nutrient availability for algal growth, indicating a proportionally higher use of methane-derived carbon in the lake's food web during peak eutrophication phases. Contributions of methane-derived carbon to the diet of the investigated invertebrates are estimated to have ranged from 0-11% during the phase with the lowest nutrient availability to 13-20% during the peak eutrophication phase. © 2017 The Author(s).

  7. Invasive mussels alter the littoral food web of a large lake: stable isotopes reveal drastic shifts in sources and flow of energy.

    Directory of Open Access Journals (Sweden)

    Ted Ozersky

    Full Text Available We investigated how establishment of invasive dreissenid mussels impacted the structure and energy sources of the littoral benthic food web of a large temperate lake. We combined information about pre- and postdreissenid abundance, biomass, and secondary production of the littoral benthos with results of carbon and nitrogen stable isotope analysis of archival (predreissenid and recent (postdreissenid samples of all common benthic taxa. This approach enabled us to determine the importance of benthic and sestonic carbon to the littoral food web before, and more than a decade after dreissenid establishment. Long term dreissenid presence was associated with a 32-fold increase in abundance, 6-fold increase in biomass, and 14-fold increase in secondary production of the littoral benthos. Dreissenids comprised a large portion of the post-invasion benthos, making up 13, 38, and 56% of total abundance, biomass, and secondary production, respectively. The predreissenid food web was supported primarily by benthic primary production, while sestonic material was relatively more important to the postdreissenid food web. The absolute importance of both sestonic material and benthic primary production to the littoral benthos increased considerably following dreissenid establishment. Our results show drastic alterations to food web structure and suggest that dreissenid mussels redirect energy and material from the water column to the littoral benthos both through biodeposition of sestonic material as well as stimulation of benthic primary production.

  8. Bioaccumulation and trophic transfer of mercury and selenium in african sub-tropical fluvial reservoirs food webs (Burkina Faso.

    Directory of Open Access Journals (Sweden)

    Ousséni Ouédraogo

    Full Text Available The bioaccumulation and biomagnification of mercury (Hg and selenium (Se were investigated in sub-tropical freshwater food webs from Burkina Faso, West Africa, a region where very few ecosystem studies on contaminants have been performed. During the 2010 rainy season, samples of water, sediment, fish, zooplankton, and mollusks were collected from three water reservoirs and analysed for total Hg (THg, methylmercury (MeHg, and total Se (TSe. Ratios of δ13C and δ15N were measured to determine food web structures and patterns of contaminant accumulation and transfer to fish. Food chain lengths (FCLs were calculated using mean δ15N of all primary consumer taxa collected as the site-specific baseline. We report relatively low concentrations of THg and TSe in most fish. We also found in all studied reservoirs short food chain lengths, ranging from 3.3 to 3.7, with most fish relying on a mixture of pelagic and littoral sources for their diet. Mercury was biomagnified in fish food webs with an enrichment factor ranging from 2.9 to 6.5 for THg and from 2.9 to 6.6 for MeHg. However, there was no evidence of selenium biomagnification in these food webs. An inverse relationship was observed between adjusted δ15N and log-transformed Se:Hg ratios, indicating that Se has a lesser protective effect in top predators, which are also the most contaminated animals with respect to MeHg. Trophic position, carbon source, and fish total length were the factors best explaining Hg concentration in fish. In a broader comparison of our study sites with literature data for other African lakes, the THg biomagnification rate was positively correlated with FCL. We conclude that these reservoir systems from tropical Western Africa have low Hg biomagnification associated with short food chains. This finding may partly explain low concentrations of Hg commonly reported in fish from this area.

  9. A Validation Study of the Automated Self-Administered 24-Hour Dietary Recall for Children, 2014 Version, at School Lunch.

    Science.gov (United States)

    Krehbiel, Caroline F; DuPaul, George J; Hoffman, Jessica A

    2017-05-01

    Obtaining valid and reliable estimates of usual dietary intake at a reasonable cost is a challenge in school-based nutrition research. The Automated Self-Administered 24-Hour Dietary Recall for Children, 2014 version (ASA24 Kids-2014), a self-administered, computerized 24-hour dietary recall, offers improved feasibility over traditional interviewer-administered 24-hour recalls. This mixed-methods study examined ASA24 Kids-2014's validity for measuring dietary intake from National School Lunch Program lunches. After 24% attrition, 96 middle-school students from three urban schools in eastern Pennsylvania participated in the study. A subsample of 27 participants completed qualitative interviews. Data were collected in the spring of 2014. Self-reported ASA24 Kids-2014 data were compared to direct observations of school lunch, which served as the criterion measure. Dependent variables included eight meal components selected from the National School Lunch Program guidelines (fruit, vegetables, grains, protein-rich foods, dairy, oils, solid fats, and added sugars). A supplemental interview collected qualitative data regarding students' perceptions of content and substantive validity. The Wilcoxon signed rank test and Spearman's ρ examined criterion-related validity; qualitative content analysis examined content and substantive validity. Participants inaccurately recalled food items eaten at lunch, as 58% of foods were reported in error. However, among foods recalled correctly, no statistically significant differences emerged for estimates of portions consumed for six meal components (fruit, vegetables, grains, protein-rich foods, oils, and added sugars). In addition, statistically significant positive correlations emerged between ASA24 Kids-2014 and direct observation for all estimates. Qualitative data identified students' interest and motivation, comprehension, memory, and English-language fluency as relevant sources of error. Middle school students have difficulty

  10. Nutrient enrichment reduces constraints on material flows in a detritus-based food web

    Science.gov (United States)

    Wyatt F. Cross; Bruce Wallace; Amy D. Rosemond

    2007-01-01

    Most aquatic and terrestrial ecosystems are experiencing increased nutrient availability, which is affecting their structure and function. By altering community composition and productivity of consumers, enrichment can indirectly cause changes in the pathways and magnitude of material flows in food webs. These changes, in turn, have major consequences for material...

  11. Recalls of microbiologically contaminated cosmetics in EU from 2005 to May 2008

    DEFF Research Database (Denmark)

    Lundov, Michael Dyrgaard; Zachariae, Claus Otto Carl

    2008-01-01

    The Rapid Alert System for non-food consumer products in the EU (RAPEX) notifies each week the member countries on dangerous products sold in the EU. Microbiological contaminated cosmetics pose a potential health risk and are recalled from the market. This study investigated the number of recalled...... of contaminated cosmetic products could be two to three times higher in 2008 compared to 2007. The recalled products were manufactured in 17 different countries and only one company had more than one product recalled. It is important to keep monitoring the cosmetic products for contamination because an increasing...... microbiological contaminated cosmetics products in the RAPEX database from 2005 to until week 17 in 2008. A total of 173 cosmetic products were recalled in the period, 24 were contaminated and the most frequently found micro-organism was the pathogenic Pseudomonas aeruginosa. It appears that the number...

  12. Microbially mediated detrital food web: The link between mangroves and coastal aquatic animal communities

    Digital Repository Service at National Institute of Oceanography (India)

    RaghuKumar, S.

    The importance of mangroves extends far beyond that which is offerEd. by their vegetation. In fact, mangroves constitute the driving force of the food web in coastal waters adjacent to them, in the form of detritus. Detritus, in simple terms, may...

  13. The Importance of Allochthonous Subsidies to an Estuarine Food Web along a Salinity Gradient

    Science.gov (United States)

    Estuarine food webs function within a heterogeneous mosaic and are supported by a mix of primary producers from both local and distant sources. Processes governing the exchange and consumption of organic matter (OM), however, are poorly understood. To study the contribution of ...

  14. WebDASC: a web-based dietary assessment software for 8-11-year-old Danish children

    DEFF Research Database (Denmark)

    Biltoft-Jensen, Anja Pia; Trolle, Ellen; Christensen, Tue

    2014-01-01

    digital images. WebDASC includes internal checks for frequently forgotten foods, and the following features to create motivation: a food-meter displaying cumulative weight of foods reported, a most popular food ranking, and a computer game with a high score list. Conclusions:  WebDASC was developed...

  15. WebDASC: a web-based dietary assessment software for 8-11-year-old Danish children

    DEFF Research Database (Denmark)

    Biltoft-Jensen, Anja Pia; Trolle, Ellen; Christensen, Tue

    digital images. WebDASC includes internal checks for frequently forgotten foods, and the following features to create motivation: a food-meter displaying cumulative weight of foods reported, a most popular food ranking, and a computer game with a high score list. Conclusions:  WebDASC was developed...

  16. Predicting Drug Recalls From Internet Search Engine Queries.

    Science.gov (United States)

    Yom-Tov, Elad

    2017-01-01

    Batches of pharmaceuticals are sometimes recalled from the market when a safety issue or a defect is detected in specific production runs of a drug. Such problems are usually detected when patients or healthcare providers report abnormalities to medical authorities. Here, we test the hypothesis that defective production lots can be detected earlier by monitoring queries to Internet search engines. We extracted queries from the USA to the Bing search engine, which mentioned one of the 5195 pharmaceutical drugs during 2015 and all recall notifications issued by the Food and Drug Administration (FDA) during that year. By using attributes that quantify the change in query volume at the state level, we attempted to predict if a recall of a specific drug will be ordered by FDA in a time horizon ranging from 1 to 40 days in future. Our results show that future drug recalls can indeed be identified with an AUC of 0.791 and a lift at 5% of approximately 6 when predicting a recall occurring one day ahead. This performance degrades as prediction is made for longer periods ahead. The most indicative attributes for prediction are sudden spikes in query volume about a specific medicine in each state. Recalls of prescription drugs and those estimated to be of medium-risk are more likely to be identified using search query data. These findings suggest that aggregated Internet search engine data can be used to facilitate in early warning of faulty batches of medicines.

  17. Carbon dynamics, food web structure and reclamation strategies in Athabasca oil sands wetlands (CRFAW)

    International Nuclear Information System (INIS)

    Ciborowski, J.; Dixon, G.; Foote, L.; Liber, K.; Smits, J.

    2010-01-01

    This abstract provided details of the Carbon Dynamics, Food Web Structure and Reclamation Strategies in Athabasca Oil Sands Wetlands (CFRAW) program, a collaboration between oil sands industry partners and university laboratories. CFRAW researchers are investigating the effects of mine tailings and process waters on the development, health, and function of wetland communities in post-mining landscapes. The aim of the program is to accurately predict how quickly the reclaimed wetlands will approach conditions seen in reference wetland systems. The program is also examining the effects of hydrocarbons as a surrogate source of carbon after they are metabolized by bacteria. The biological uptake, pathways, and movement through the food web of materials used by the biota in constructed wetlands are also being studied. Flux estimates will be used to determine if wetlands amended with peat will maintain their productivity. A conceptual model of carbon pathways and budgets is also being developed.

  18. Salinity shapes food webs in shallow lakes: implications for increasing aridity with climate change

    DEFF Research Database (Denmark)

    Vidal, Nicolas; Yu, Jinlei; Gutierrez, Maria Florencia

    2015-01-01

    on community and food web structure in 24 lakes along a wide salinity gradient, from freshwater (0.5 g L-1) to hypersaline lakes (115 g L-1), in a semiarid region in North West China. Fish, zooplankton and macroinvertebrate communities were sampled during July 2014 for determination of taxonomy and size......A reduction in runoff and higher evaporation rates are expected to occur towards 2050 in arid and semiarid regions of the world, resulting in a reduction of water level and salinization of inland waters. Besides the natural process of catchment erosion, human activities such as irrigation of crops...... may also increase salinization. Reduced biodiversity in freshwater systems is the most commonly reported effect of salinization, which may have implications for food web structure and likely for ecosystem functioning as well. The objective of the study was to analyze the effects of salinity...

  19. Food webs including parasites, biomass, body sizes, and life stages for three California/Baja California estuaries

    Science.gov (United States)

    Hechinger, Ryan F.; Lafferty, Kevin D.; McLaughlin, John P.; Fredensborg, Brian L.; Huspeni, Todd C.; Lorda, Julio; Sandhu, Parwant K.; Shaw, Jenny C.; Torchin, Mark E.; Whitney, Kathleen L.; Kuris, Armand M.

    2001-01-01

    This data set presents food webs for three North American Pacific coast estuaries and a “Metaweb” composed of the species/stages compiled from all three estuaries. The webs have four noteworthy attributes: (1) parasites (infectious agents), (2) body-size information, (3) biomass information, and (4) ontogenetic stages of many animals with complex life cycles. The estuaries are Carpinteria Salt Marsh, California (CSM); Estero de Punta Banda, Baja California (EPB); and Bahía Falsa in Bahía San Quintín, Baja California (BSQ). Most data on species assemblages and parasitism were gathered via consistent sampling that acquired body size and biomass information for plants and animals larger than ∼1 mm, and for many infectious agents (mostly metazoan parasites, but also some microbes). We augmented this with information from additional published sources and by sampling unrepresented groups (e.g., plankton). We estimated free-living consumer–resource links primarily by extending a previously published version of the CSM web (which the current CSM web supplants) and determined most parasite consumer–resource links from direct observation. We recognize 21 possible link types including four general interactions: predators consuming prey, parasites consuming hosts, predators consuming parasites, and parasites consuming parasites. While generally resolved to the species level, we report stage-specific nodes for many animals with complex life cycles. We include additional biological information for each node, such as taxonomy, lifestyle (free-living, infectious, commensal, mutualist), mobility, and residency. The Metaweb includes 500 nodes, 314 species, and 11 270 links projected to be present given appropriate species' co-occurrences. Of these, 9247 links were present in one or more of the estuarine webs. The remaining 2023 links were not present in the estuaries but are included here because they may occur in other places or times. Initial analyses have examined

  20. Basal mercury concentrations and biomagnification rates in freshwater and marine food webs: Effects on Arctic charr (Salvelinus alpinus) from eastern Canada

    International Nuclear Information System (INIS)

    Velden, S. van der; Dempson, J.B.; Evans, M.S.; Muir, D.C.G.; Power, M.

    2013-01-01

    Patterns of total Hg (THg) and methyl Hg (MeHg) biomagnification were investigated in six pairs of co-located lacustrine and marine food webs supporting a common predator, Arctic charr. Mercury biomagnification rates (the slope of log Hg concentration versus δ 15 N-inferred trophic level) did not differ significantly between the two feeding habitats for either THg or MeHg, but THg and MeHg concentrations at the base of the food web were higher in the lacustrine environment than in the marine environment. The proportion of THg as MeHg was related to trophic level, and the relationship was statistically similar in the lacustrine and marine habitats. The biomagnification rate of MeHg exceeded that of THg in both habitats. We conclude that the known difference in Hg concentration between anadromous and non-anadromous Arctic charr is driven by differential Hg concentrations at the base of the lacustrine and marine foodwebs, and not by differential biomagnification rates. - Highlights: ► Concentrations of total mercury ([THg]) and methylmercury ([MeHg]) were measured in 6 paired lacustrine and marine food webs. ► Biomagnification rates (slopes of [THg] or [MeHg] versus δ 15 N-inferred trophic level) were similar in the two habitat types. ► Mercury concentrations at the base of the food web were higher in lacustrine than in marine food webs. ► The percentage of methylated mercury increased with trophic level similarly in the two habitat types. ► The biomagnification rate of MeHg exceeded that of THg in both habitats

  1. Economic Factors Impacting Food Allergen Management: Perspectives from the Food Industry.

    Science.gov (United States)

    Gupta, Ruchi S; Taylor, Steve L; Baumert, Joseph L; Kao, Lauren M; Schuster, Erik; Smith, Bridget M

    2017-10-01

    Food allergies affect up to 8% of children in the United States and may occasionally lead to severe life-threatening reactions. Because there is currently no cure for food allergies, strict avoidance of the allergen-containing foods is the only means of preventing an allergic reaction. Consumers rely on food manufacturers to reliably track and declare the presence of food allergens in products. Over the past 10 to 20 years, the food industry has increasingly adopted allergen control approaches in its processing facilities. However, the major industry costs related to food allergen management have not been fully described. The objective of this study was to characterize the factors that contribute to the economic impact of food allergen control practices on the food industry. A focus group (n = 100) was conducted with food industry professionals to identify key areas of cost for food allergen management. A survey based on the domains identified was then developed and disseminated to a convenience sample (n = 50) of quality control food industry specialists with knowledge of their company's food allergen management practices. Nearly all companies (92%) produced food products containing one or more of the top eight allergenic foods recognized by the U.S. Food and Drug Administration or sesame seeds. Cleaning procedures, employee training, and the potential for a recall due to allergen cross-contact were most frequently rated as the important factors in food allergen management. Recalls due to food allergen cross-contact, cleaning procedures, equipment and premises design, and employee training were ranked as the greatest allergen management expenses. Although 96% of companies had a food allergen control plan in place, nearly half (42%) had at least one food allergen-related recall within the past 5 years. The industry appears to endorse a willingness to unify precautionary allergen labeling to communicate a clear message more effectively to consumers.

  2. Interested in Pelagic Food Webs? BCO-DMO has your Data.

    Science.gov (United States)

    Chandler, C. L.; Groman, R. C.; Kinkade, D.; Rauch, S.; Allison, M. D.; Gegg, S. R.; Shepherd, A.; Wiebe, P. H.; Glover, D. M.

    2016-02-01

    Interdisciplinary research collaborations that address complex, global research themes such as the interactive effects of global warming and studies of pelagic food webs require access to a broad range of data types from all disciplines of oceanography, from all platforms (e.g. ships, gliders, floats, moorings), with the in situ observations complementing and being complemented by laboratory and model results. In an effort to build a comprehensive database of marine ecosystem research data, the National Science Foundation (NSF) funded the Biological and Chemical Oceanography Data Management Office (BCO-DMO; bco-dmo.org) to support the data management requirements of investigators funded by the NSF's Polar Programs (PLR) and Biological and Chemical Oceanography Sections (OCE). Since 2006, investigators funded by NSF PLR and OCE have been working with support from BCO-DMO data scientists, to build a data system that now includes the full range of ocean biogeochemistry data resulting from decades of research. In addition to data from recently funded PIs, the BCO-DMO data system also serves data from legacy programs (e.g. US Joint Global Ocean Flux Study and US Global Ocean Ecosystem Dynamics). The data are open-access, available for download in a variety of user-selectable formats, and accompanied by sufficient documentation to enable re-use. This presentation will highlight the diversity of data available from the BCO-DMO system and demonstrate some of the features that enable discovery, access and download of data relevant to studies of pelagic food webs.

  3. Parasites as prey in aquatic food webs: implications for predator infection and parasite transmission

    NARCIS (Netherlands)

    Thieltges, D.W.; Amundsen, P.-A.; Hechinger, R.F.; Johnson, P.T.J.; Lafferty, K.D.; Mouritsen, K.N.; Preston, D.L.; Reise, K.; Zander, C.D.; Poulin, R.

    2013-01-01

    While the recent inclusion of parasites into food-web studies has highlighted the role of parasites as consumers, there is accumulating evidence that parasites can also serve as prey for predators. Here we investigated empirical patterns of predation on parasites and their relationships with

  4. Data from: How habitat-modifying organisms structure the food web of two coastal ecosystems

    NARCIS (Netherlands)

    Zee, van der Els M.; Angelini, Christine; Govers, Laura L.; Christianen, M.J.A.; Altieri, Andrew H.; Reijden, van der K.J.; Silliman, Brian R.; Koppel, van de Johan; Geest, van der Matthijs; Gils, van Jan A.; Veer, van der Henk W.; Piersma, Theunis; Ruiter, de P.C.; Olff, H.; Heide, van der Tjisse

    2016-01-01

    The diversity and structure of ecosystems has been found to depend both on trophic interactions in food webs and on other species interactions such as habitat modification and mutualism that form non-trophic interaction networks. However, quantification of the dependencies between these two main

  5. Adaptive Memory: Animacy Enhances Free Recall but Impairs Cued Recall

    Science.gov (United States)

    Popp, Earl Y.; Serra, Michael J.

    2016-01-01

    Recent research suggests that human memory systems evolved to remember animate things better than inanimate things. In the present experiments, we examined whether these effects occur for both free recall and cued recall. In Experiment 1, we directly compared the effect of animacy on free recall and cued recall. Participants studied lists of…

  6. Blending technology and teamwork for successful management of product recalls.

    Science.gov (United States)

    Frush, Karen; Pleasants, Jane; Shulby, Gail; Hendrix, Barbara; Berson, Brooke; Gordon, Cynthia; Cuffe, Michael S

    2009-12-01

    Patient safety programs have been developed in many hospitals to reduce the risk of harm to patients. Proactive, real-time, and retrospective risk-reduction strategies should be implemented in hospitals, but patient safety leaders should also be cognizant of the risks associated with thousands of products that enter the hospital through the supply chain. A growing number of recalls and alerts related to these products are received by health care facilities each year, through a recall process that is fraught with challenges. Despite the best efforts of health care providers, weaknesses and gaps in the process lead to delays, fragmentation, and disruptions, thus extending the number of days patients may be at risk from potentially faulty or misused products. To address these concerns, Duke Medicine, which comprises an academic medical center, two community hospitals, outlying clinics, physicians' offices, and home health and hospice, implemented a Web-based recall management system. Within three months, the time required to receive, deliver, and close alerts decreased from 43 days to 2.74 days. To maximize the effectiveness of the recall management process, a team of senior Duke Medicine leaders was established to evaluate the impact of product recalls and alerts on patient safety, to evaluate response action plans, and to provide oversight of patient and provider communication strategies. Alerts are now communicated more effectively and responded to in a more consistent and global manner. This comprehensive approach to product recalls is a critical component of a broader Duke Medicine strategy to improve patient safety.

  7. Identification of trophic interactions within an estuarine food web (northern New Zealand) using fatty acid biomarkers and stable isotopes

    Science.gov (United States)

    Alfaro, Andrea C.; Thomas, François; Sergent, Luce; Duxbury, Mark

    2006-10-01

    Fatty acid biomarkers and stable isotope signatures were used to identify the trophic dynamics of a mangrove/seagrass estuarine food web at Matapouri, northern New Zealand. Specific fatty acids were used to identify the preferred food sources (i.e., mangroves, seagrass, phytoplankton, macroalgae, bacteria, and zooplankton) of dominant fauna (i.e., filter feeders, grazing snails, scavenger/predatory snails, shrimp, crabs, and fish), and their presence in water and sediment samples throughout the estuary. The diets of filter feeders were found to be dominated by dinoflagellates, whereas grazers showed a higher diatom contribution. Bacteria associated with organic debris on surface sediments and brown algal ( Hormosira banksii) material in the form of suspended organic matter also accounted for a high proportion of most animal diets. Animals within higher trophic levels had diverse fatty acid profiles, revealing their varied feeding strategies and carbon sources. The stable isotope (δ 13C and δ 15N) analyses of major primary producers and consumers/predators revealed a trend of 15N enrichment with increasing trophic level, while δ 13C values provided a generally good description of carbon flow through the food web. Overall results from both fatty acid profiles and stable isotopes indicate that a variety of carbon sources with a range of trophic pathways typify this food web. Moreover, none of the animals studied was dependent on a single food source. This study is the first to use a comprehensive fatty acid biomarker and stable isotope approach to investigate the food web dynamics within a New Zealand temperate mangrove/seagrass estuary. This quantitative research may contribute to the currently developing management strategies for estuaries in northern New Zealand, especially for those perceived to have expanding mangrove fringes.

  8. Tracing carbon flow through coral reef food webs using a compound-specific stable isotope approach

    KAUST Repository

    McMahon, Kelton; Thorrold, Simon R.; Houghton, Leah A.; Berumen, Michael L.

    2015-01-01

    . Seascape configuration played an important role in structuring resource utilization patterns. For instance, Lutjanus ehrenbergii showed a significant shift from a benthic macroalgal food web on shelf reefs (71 ± 13 % of dietary C) to a phytoplankton

  9. Trophic structure and mercury distribution in a Gulf of St. Lawrence (Canada) food web using stable isotope analysis

    International Nuclear Information System (INIS)

    Lavoie, Raphael A.; Hebert, Craig E.; Rail, Jean-Francois; Braune, Birgit M.; Yumvihoze, Emmanuel; Hill, Laura G.; Lean, David R.S.

    2010-01-01

    Even at low concentrations in the environment, mercury has the potential to biomagnify in food chains and reaches levels of concern in apex predators. The aim of this study was to relate the transfer of total mercury (THg) and methylmercury (MeHg) in a Gulf of St. Lawrence food web to the trophic structure, from primary consumers to seabirds, using stable nitrogen (δ 15 N) and carbon (δ 13 C) isotope analysis and physical environmental parameters. The energy reaching upper trophic level species was principally derived from pelagic primary production, with particulate organic matter (POM) at the base of the food chain. We developed a biomagnification factor (BMF) taking into account the various prey items consumed by a given predator using stable isotope mixing models. This BMF provides a more realistic estimation than when using a single prey. Lipid content, body weight, trophic level and benthic connection explained 77.4 and 80.7% of the variation in THg and MeHg concentrations, respectively in this food web. When other values were held constant, relationships with lipid and benthic connection were negative whereas relationships with trophic level and body weight were positive. Total Hg and MeHg biomagnified in this food web with biomagnification power values (slope of the relationship with δ 15 N) of 0.170 and 0.235, respectively on wet weight and 0.134 and 0.201, respectively on dry weight. Values of biomagnification power were greater for pelagic and benthopelagic species compared to benthic species whereas the opposite trend was observed for levels at the base of the food chain. This suggests that Hg would be readily bioavailable to organisms at the base of the benthic food chain, but trophic transfer would be more efficient in each trophic level of pelagic and benthopelagic food chains.

  10. Food web structure shaped by habitat size and climate across a latitudinal gradient.

    Science.gov (United States)

    Romero, Gustavo Q; Piccoli, Gustavo C O; de Omena, Paula M; Gonçalves-Souza, Thiago

    2016-10-01

    Habitat size and climate are known to affect the trophic structure and dynamics of communities, but their interactive effects are poorly understood. Organisms from different trophic levels vary in terms of metabolic requirements and heat dissipation. Indeed, larger species such as keystone predators require more stable climatic conditions than their prey. Likewise, habitat size disproportionally affects large-sized predators, which require larger home ranges and are thus restricted to larger habitats. Therefore, food web structure in patchy ecosystems is expected to be shaped by habitat size and climate variations. Here we investigate this prediction using natural aquatic microcosm (bromeliad phytotelmata) food webs composed of litter resources (mainly detritus), detritivores, mesopredators, and top predators (damselflies). We surveyed 240 bromeliads of varying sizes (water retention capacity) across 12 open restingas in SE Brazil spread across a wide range of tropical latitudes (-12.6° to -27.6°, ca. 2,000 km) and climates (Δ mean annual temperature = 5.3°C). We found a strong increase in predator-to-detritivore mass ratio with habitat size, which was representative of a typical inverted trophic pyramid in larger ecosystems. However, this relationship was contingent among the restingas; slopes of linear models were steeper in more stable and favorable climates, leading to inverted trophic pyramids (and top-down control) being more pronounced in environments with more favorable climatic conditions. By contrast, detritivore-resource and mesopredator-detritivore mass ratios were not affected by habitat size or climate variations across latitudes. Our results highlight that the combined effects of habitat size, climate and predator composition are pivotal to understanding the impacts of multiple environmental factors on food web structure and dynamics. © 2016 by the Ecological Society of America.

  11. Assessing the Health of Puget Sound's Pelagic Food Web at Multiple Trophic Levels

    Science.gov (United States)

    Rhodes, L. D.; Greene, C. M.; Rice, C. A.; Hall, J. E.; Baxter, A. E.; Naman, S. M.; Chamberlin, J.

    2012-12-01

    Puget Sound is an estuarine fjord in the northwestern United State surrounded by variable upland uses, ranging from industrial and urban to agricultural to forested lands. The quality of Puget Sound's ecosystem is under scrutiny because of the biological resources that depend on its function. In 2011, we undertook a study of the Sound's pelagic food web that measured water quality, microbial parameters, and abundance of higher trophic levels including gelatinous zooplankton, forage fish, and salmon. More than 75 sites spanning the latitudinal expanse of Puget Sound and the range of developed and agricultural land uses were sampled monthly from April to October. Strong relationships between water quality and microbial parameters suggest that microbes may modulate water quality indicators, such as dissolved inorganic nitrogen and pH, and that land use may be an influential factor. Basins within Puget Sound exhibit distinct biological profiles at the microbial and macrobiotic levels, emphasizing that Puget Sound is not a homogenous water body and suggesting that informative food web indicators may vary across the basins.

  12. Failure to recall.

    Science.gov (United States)

    Laming, Donald

    2009-01-01

    Mathematical analysis shows that if the pattern of rehearsal in free-recall experiments (of necessity, the pattern observed when participants rehearse aloud) be continued without any further interruption by stimuli (as happens during recall), it terminates with the retrieval of the same 1 word over and over again. Such a terminal state is commonly reached before some of the words in the list have been retrieved even once; those words are not recalled. The 1 minute frequently allowed for recall in free-recall experiments is ample time for retrieval to seize up in this way. The author proposes a model that represents the essential features of the pattern of rehearsal; validates that model by reference to the overt rehearsal data from B. B. Murdock, Jr., and J. Metcalfe (1978) and the recall data from B. B. Murdock, Jr., and R. Okada (1970); demonstrates the long-term properties of continued sequences of retrievals and, also, a fundamental relation linking recall to the total time of presentation; and, finally, compares failure to recall in free-recall experiments with forgetting in general.

  13. Terrestrial contributions to the aquatic food web in the middle Yangtze River.

    Directory of Open Access Journals (Sweden)

    Jianzhu Wang

    Full Text Available Understanding the carbon sources supporting aquatic consumers in large rivers is essential for the protection of ecological integrity and for wildlife management. The relative importance of terrestrial and algal carbon to the aquatic food webs is still under intensive debate. The Yangtze River is the largest river in China and the third longest river in the world. The completion of the Three Gorges Dam (TGD in 2003 has significantly altered the hydrological regime of the middle Yangtze River, but its immediate impact on carbon sources supporting the river food web is unknown. In this study, potential production sources from riparian and the main river channel, and selected aquatic consumers (invertebrates and fish at an upstream constricted-channel site (Luoqi, a midstream estuarine site (Huanghua and a near dam limnetic site (Maoping of the TGD were collected for stable isotope (δ13C and δ15N and IsoSource analyses. Model estimates indicated that terrestrial plants were the dominant carbon sources supporting the consumer taxa at the three study sites. Algal production appeared to play a supplemental role in supporting consumer production. The contribution from C4 plants was more important than that of C3 plants at the upstream site while C3 plants were the more important carbon source to the consumers at the two impacted sites (Huanghua and Maoping, particularly at the midstream site. There was no trend of increase in the contribution of autochthonous production from the upstream to the downstream sites as the flow rate decreased dramatically along the main river channel due to the construction of TGD. Our findings, along with recent studies in rivers and lakes, are contradictory to studies that demonstrate the importance of algal carbon in the aquatic food web. Differences in system geomorphology, hydrology, habitat heterogeneity, and land use may account for these contradictory findings reported in various studies.

  14. Food Web Responses to Artificial Mixing in a Small Boreal Lake

    Directory of Open Access Journals (Sweden)

    Lauri Arvola

    2017-07-01

    Full Text Available In order to simulate food web responses of small boreal lakes to changes in thermal stratification due to global warming, a 4 year whole-lake manipulation experiment was performed. Within that time, period lake mixing was intensified artificially during two successive summers. Complementary data from a nearby lake of similar size and basic water chemistry were used as a reference. Phytoplankton biomass and chlorophyll a did not respond to the greater mixing depth but an increase was observed in the proportional abundance of diatoms, and the proportional abundance of cryptophytes also increased immediately after the onset of mixing. Obligate anoxic green sulphur bacteria vanished at the onset of mixing but gradually recovered after re-establishment of hypolimnetic anoxic conditions. No major effect on crustacean zooplankton was found, but their diversity increased in the metalimnion. During the mixing, the density of rotifers declined but protozoan density increased in the hypolimnion. Littoral benthic invertebrate density increased during the mixing due to Ephemeroptera, Asellus aquaticus and Chironomidae, whereas the density of Chaoborus larvae declined during mixing and lower densities were still recorded one year after the treatment. No structural changes in fish community were found although gillnet catches increased after the onset of the study. The early growth of perch (Perca fluviatilis increased compared to the years before the mixing and in comparison to the reference lake, suggesting improved food availability in the experimental lake. Although several food web responses to the greater mixing depth were found, their persistence and ecological significance were strongly dependent on the extent of the disturbance. To better understand the impacts of wind stress on small lakes, long term whole-lake experiments are needed.

  15. ARCTOX: a pan-Arctic sampling network to track mercury contamination across Arctic marine food webs

    DEFF Research Database (Denmark)

    Fort, Jerome; Helgason, Halfdan; Amelineau, Francoise

    and is still a source of major environmental concerns. In that context, providing a large-scale and comprehensive understanding of the Arctic marine food-web contamination is essential to better apprehend impacts of anthropogenic activities and climate change on the exposure of Arctic species and humans to Hg....... In 2015, an international sampling network (ARCTOX) has been established, allowing the collection seabird samples all around the Arctic. Seabirds are indeed good indicators of Hg contamination of marine food webs at large spatial scale. Gathering researchers from 10 countries, ARCTOX allowed......Arctic marine ecosystems are threatened by new risks of Hg contamination under the combined effects of climate change and human activities. Rapid change of the cryosphere might for instance release large amounts of Hg trapped in sea-ice, permafrost and terrestrial glaciers over the last decades...

  16. Effects of hydrological forcing on the structure of a tropical estuarine food web

    Science.gov (United States)

    Trisha B. Atwood; Tracy N. Wiegner; Richard A. MacKenzie

    2012-01-01

    River flow can impact which sources of particulate organic matter (POM) fuel estuarine food webs. Here, we used stable carbon (C) and nitrogen (N) isotope analyses to compare how contributions of diff erent POM sources (terrestrial, estuarine, and marine) to the diets of zooplankton and juvenile fishes differed between low and high river flow conditions, as well as...

  17. The energetic contributions of aquatic primary producers to terrestrial food webs in a mid-size river system.

    Science.gov (United States)

    Kautza, Adam; Mazeika, S; Sullivan, P

    2016-03-01

    Rivers are increasingly recognized as providing nutritional subsidies (i.e., energy and nutrients) to adjacent terrestrial food webs via depredation of aquatic organisms (e.g., emergent aquatic insects, crayfish, fish) by terrestrial consumers. However, because these prey organisms assimilate energy from both aquatic (e.g., benthic algae, phytoplankton, aquatic macrophytes) and terrestrial (e.g., riparian leaf detritus) primary producers, river subsidies to terrestrial consumers represent a combination of aquatically and terrestrially derived energy. To date, the explicit contribution of energy derived from aquatic primary producers to terrestrial consumers has not been fully explored yet might be expected to be quantitatively important to terrestrial food webs. At 12 reaches along a 185-km segment of the sixth-order Scioto River system (Ohio, USA), we quantified the relative contribution of energy derived from aquatic primary producers to a suite of terrestrial riparian consumers that integrate the adjacent landscape across multiple spatial scales through their foraging activities (tetragnathid spiders, rove beetles, adult coenagrionid damselflies, riparian swallows, and raccoons). We used naturally abundant stable isotopes (13C and 15N) of periphyton, phytoplankton, macrophytes, and terrestrial vegetation to evaluate the energetic contribution of aquatic primary producers to terrestrial food webs. Shoreline tetragnathid spiders were most reliant on aquatic primary producers (50%), followed by wider-ranging raccoons (48%), damselflies (44%), and riparian swallows (41%). Of the primary producers, phytoplankton (19%) provisioned the greatest nutritional contribution to terrestrial consumers (considered collectively), followed by periphyton (14%) and macrophytes (11%). Our findings provide empirical evidence that aquatic primary producers of large streams and rivers can be a critical nutritional resource for terrestrial food webs. We also show that aquatically

  18. Teachers’ use of dietary recalls for exploratory dialogue in the classroom

    DEFF Research Database (Denmark)

    Torres, Irene

    2017-01-01

    Objective: This study examines teachers’ adoption and adaptation of 24-hour dietary recall technique for exploratory dialogue in the classroom with students aged 8–12 years. The focus is on the teachers’ use of the information collected through the recall tool to pose open questions, recap...... teachers. Results: Teachers using the recalls as shared objects of learning guided the class through a collaborative process of sensemaking and understanding of their food practices. Based on children’s everyday knowledge and experiences, the teachers helped to search for explanations and solutions....... The tool has potential for teachers to develop instructional skills regarding the discussion of nutrition and health practices within pre-service or in-service training....

  19. Factors affecting biotic mercury concentrations and biomagnification through lake food webs in the Canadian high Arctic

    Energy Technology Data Exchange (ETDEWEB)

    Lescord, Gretchen L., E-mail: glescord@gmail.com [University of New Brunswick/Canadian Rivers Institute, 100 Tucker Park Rd, Saint John, NB E2L 4A6 (Canada); Kidd, Karen A. [University of New Brunswick/Canadian Rivers Institute, 100 Tucker Park Rd, Saint John, NB E2L 4A6 (Canada); Kirk, Jane L. [Environment Canada, Aquatic Contaminants Research Division, 867 Lakeshore Rd, Burlington, ON L7S 1A1 (Canada); O' Driscoll, Nelson J. [Acadia University, 15 University Ave, Wolfville, NS B4P 2R6 (Canada); Wang, Xiaowa; Muir, Derek C.G. [Environment Canada, Aquatic Contaminants Research Division, 867 Lakeshore Rd, Burlington, ON L7S 1A1 (Canada)

    2015-03-15

    In temperate regions of Canada, mercury (Hg) concentrations in biota and the magnitude of Hg biomagnification through food webs vary between neighboring lakes and are related to water chemistry variables and physical lake features. However, few studies have examined factors affecting the variable Hg concentrations in landlocked Arctic char (Salvelinus alpinus) or the biomagnification of Hg through their food webs. We estimated the food web structure of six high Arctic lakes near Resolute Bay, Nunavut, Canada, using stable carbon (δ{sup 13}C) and nitrogen (δ{sup 15}N) isotopes and measured Hg (total Hg (THg) in char, the only fish species, and methylmercury (MeHg) in chironomids and zooplankton) concentrations in biota collected in 2010 and 2011. Across lakes, δ{sup 13}C showed that benthic carbon (chironomids) was the dominant food source for char. Regression models of log Hg versus δ{sup 15}N (of char and benthic invertebrates) showed positive and significant slopes, indicting Hg biomagnification in all lakes, and higher slopes in some lakes than others. However, no principal components (PC) generated using all water chemistry data and physical characteristics of the lakes predicted the different slopes. The PC dominated by aqueous ions was a negative predictor of MeHg concentrations in chironomids, suggesting that water chemistry affects Hg bioavailability and MeHg concentrations in these lower-trophic-level organisms. Furthermore, regression intercepts were predicted by the PCs dominated by catchment area, aqueous ions, and MeHg. Weaker relationships were also found between THg in small char or MeHg in pelagic invertebrates and the PCs dominated by catchment area, and aqueous nitrate and MeHg. Results from these high Arctic lakes suggest that Hg biomagnification differs between systems and that their physical and chemical characteristics affect Hg concentrations in lower-trophic-level biota. - Highlights: • Mercury (Hg) in Arctic char and invertebrates

  20. Trait- and size-based descriptions of trophic links in freshwater food webs: current status and perspectives

    Directory of Open Access Journals (Sweden)

    David S. Boukal

    2014-04-01

    Full Text Available Biotic interactions in aquatic communities are dominated by predation, and the distribution of trophic link strengths in aquatic food webs crucially impacts their dynamics and stability. Although individual body size explains a large proportion of variation in trophic link strengths in aquatic habitats, current predominately body size-based views can gain additional realism by incorporating further traits. Functional traits that potentially affect the strength of trophic links can be classified into three groups: i body size, ii traits that identify the spatiotemporal overlap between the predators and their prey, and iii predator foraging and prey vulnerability traits, which are readily available for many taxa. Relationship between these trait groups and trophic link strength may be further modified by population densities, habitat complexity, temperature and other abiotic factors. I propose here that this broader multi-trait framework can utilize concepts, ideas and existing data from research on metabolic ecology, ecomorphology, animal personalities and role of habitats in community structuring. The framework can be used to investigate non-additive effects of traits on trophic interactions, shed more light on the structuring of local food webs and evaluate the merits of taxonomic and functional group approaches in the description of predator-prey interactions. Development of trait- and size-based descriptions of food webs could be particularly fruitful in limnology given the relative paucity of well resolved datasets in standing waters. 

  1. Antibiotic Pollution in Marine Food Webs in Laizhou Bay, North China: Trophodynamics and Human Exposure Implication.

    Science.gov (United States)

    Liu, Sisi; Zhao, Hongxia; Lehmler, Hans-Joachim; Cai, Xiyun; Chen, Jingwen

    2017-02-21

    Little information is available about the bioaccumulation and biomagnification of antibiotics in marine food webs. Here, we investigate the levels and trophic transfer of 9 sulfonamide (SA), 5 fluoroquinolone (FQ), and 4 macrolide (ML) antibiotics, as well as trimethoprim in nine invertebrate and ten fish species collected from a marine food web in Laizhou Bay, North China in 2014 and 2015. All the antibiotics were detected in the marine organisms, with SAs and FQs being the most abundant antibiotics. Benthic fish accumulated more SAs than invertebrates and pelagic fish, while invertebrates exhibited higher FQ levels than fish. Generally, SAs and trimethoprim biomagnified in the food web, while the FQs and MLs were biodiluted. Trophic magnification factors (TMF) were 1.2-3.9 for SAs and trimethoprim, 0.3-1.0 for FQs and MLs. Limited biotransformation and relatively high assimilation efficiencies are the likely reasons for the biomagnification of SAs. The pH dependent distribution coefficients (log D) but not the lipophilicity (log K OW ) of SAs and FQs had a significant correlation (r = 0.73; p < 0.05) with their TMFs. Although the calculated estimated daily intakes (EDI) for antibiotics suggest that consumption of seafood from Laizhou Bay is not associated with significant human health risks, this study provides important insights into the guidance of risk management of antibiotics.

  2. Influence of Black Mangrove Expansion on Salt Marsh Food Web Dynamics in Coastal Louisiana

    Science.gov (United States)

    Powell, C.; Baustian, M. M.; Polito, M. J.

    2017-12-01

    The range of black mangroves (Avicennia germinans) is projected to expand in the northern Gulf of Mexico due to reduced winter freeze events and an increased rate of droughts. The colonization of mangroves in salt marshes alters habitat structure and creates a novel basal carbon source for consumers. This addition may modify trophic linkages and the structure of estuarine food webs. To understand the implications of mangrove expansion on food web dynamics of traditional Spartina alterniflora marshes, two sites in coastal Louisiana with three habitat types, marsh-dominated, mangrove-dominated, and a transition or mix of the two, were studied. Community composition of juvenile nekton was sampled using fyke nets, minnow traps, and suction sampling and analyzed for abundance and diversity. Primary carbon sources (emergent vegetation, phytoplankton, macroalgae, benthic microalgae, submerged aquatic vegetation, and soil organic matter) and consumers ((blue crabs (Callinectes sapidus), brown shrimp (Farfantepenaeus aztecus), grass shrimp (Palaemonetes spp.), Gulf killifish (Fundulus grandis), periwinkle snails (Littoraria irrorata), eastern oysters (Crassostrea virginica), and southern ribbed mussels (Geukensia granosissima)) collected at each habitat type were measured using stable isotope analysis (δ13C, δ15N, δ34S) to identify trophic level, basal carbon sources, and assess how mangrove carbon is incorporated into salt marsh food webs. While data analysis is ongoing, preliminary results indicate that basal carbon sources supporting some marsh consumers (e.g., periwinkle snails) shift between habitat types, while others remain static (e.g., grass shrimp). This research will further develop our understanding of how climate induced shifts in vegetation influences valued marsh-dependent consumers in the estuarine ecosystems of northern Gulf of Mexico.

  3. Is the relationship between pattern recall and decision-making influenced by anticipatory recall?

    Science.gov (United States)

    Gorman, Adam D; Abernethy, Bruce; Farrow, Damian

    2013-01-01

    The present study compared traditional measures of pattern recall to measures of anticipatory recall and decision-making to examine the underlying mechanisms of expert pattern perception and to address methodological limitations in previous studies where anticipatory recall has generally been overlooked. Recall performance in expert and novice basketball players was measured by examining the spatial error in recalling player positions both for a target image (traditional recall) and at 40-ms increments following the target image (anticipatory recall). Decision-making performance was measured by comparing the participant's response to those identified by a panel of expert coaches. Anticipatory recall was observed in the recall task and was significantly more pronounced for the experts, suggesting that traditional methods of spatial recall analysis may not have provided a completely accurate determination of the full magnitude of the experts' superiority. Accounting for anticipatory recall also increased the relative contribution of recall skill to decision-making accuracy although the gains in explained variance were modest and of debatable functional significance.

  4. The effects of recall-concurrent visual-motor distraction on picture and word recall.

    Science.gov (United States)

    Warren, M W

    1977-05-01

    The dual-coding model (Paivio, 1971, 1975) predicts a larger imaginal component in the recall of pictures relative to words and a larger imaginal component in the recall of concrete words relative to abstract words. These predictions were tested by examining the effect of a recall-concurrent imagery-suppression task (pursuit-rotor tracking) on the recall of pictures vs picture labels and on the recall of concrete words vs abstract words. The results showed that recall-concurrent pursuit-rotor tracking interfered with picture recall, but not word recall (Experiments 1 and 2); however, there was no evidence of an effect of recall-concurrent tracking on the recall of concrete words (Experiment 3). The results suggested a revision of the dual-coding model.

  5. Early Cretaceous terrestrial ecosystems in East Asia based on food-web and energy-flow models

    Science.gov (United States)

    Matsukawa, M.; Saiki, K.; Ito, M.; Obata, I.; Nichols, D.J.; Lockley, M.G.; Kukihara, R.; Shibata, K.

    2006-01-01

    In recent years, there has been global interest in the environments and ecosystems around the world. It is helpful to reconstruct past environments and ecosystems to help understand them in the present and the future. The present environments and ecosystems are an evolving continuum with those of the past and the future. This paper demonstrates the contribution of geology and paleontology to such continua. Using fossils, we can make an estimation of past population density as an ecosystem index based on food-web and energy-flow models. Late Mesozoic nonmarine deposits are distributed widely on the eastern Asian continent and contain various kinds of fossils such as fishes, amphibians, reptiles, dinosaurs, mammals, bivalves, gastropods, insects, ostracodes, conchostracans, terrestrial plants, and others. These fossil organisms are useful for late Mesozoic terrestrial ecosystem reconstruction using food-web and energy-flow models. We chose Early Cretaceous fluvio-lacustrine basins in the Choyr area, southeastern Mongolia, and the Tetori area, Japan, for these analyses and as a potential model for reconstruction of other similar basins in East Asia. The food-web models are restored based on taxa that occurred in these basins. They form four or five trophic levels in an energy pyramid consisting of rich primary producers at its base and smaller biotas higher in the food web. This is the general energy pyramid of a typical ecosystem. Concerning the population densities of vertebrate taxa in 1 km2 in these basins, some differences are recognized between Early Cretaceous and the present. For example, Cretaceous estimates suggest 2.3 to 4.8 times as many herbivores and 26.0 to 105.5 times the carnivore population. These differences are useful for the evaluation of past population densities of vertebrate taxa. Such differences may also be caused by the different metabolism of different taxa. Preservation may also be a factor, and we recognize that various problems occur in

  6. Community diversity, structure and carbon footprint of nematode food web following reforestation on degraded Karst soil.

    Science.gov (United States)

    Hu, Ning; Li, Hui; Tang, Zheng; Li, Zhongfang; Tian, Jing; Lou, Yilai; Li, Jianwei; Li, Guichun; Hu, Xiaomin

    2016-06-17

    We examined community diversity, structure and carbon footprint of nematode food web along a chronosequence of T. Sinensis reforestation on degraded Karst. In general, after the reforestation: a serious of diversity parameters and community indices (Shannon-Weinier index (H'), structure index (SI), etc.) were elevated; biomass ratio of fungivores to bacterivores (FFC/BFC), and fungi to bacteria (F/B) were increased, and nematode channel ratio (NCR) were decreased; carbon footprints of all nematode trophic groups, and biomass of bacteria and fungi were increased. Our results indicate that the Karst aboveground vegetation restoration was accompanied with belowground nematode food web development: increasing community complexity, function and fungal dominance in decomposition pathway, and the driving forces included the bottom-up effect (resource control), connectedness of functional groups, as well as soil environments.

  7. Abundance and biomass responses of microbial food web components to hydrology and environmental gradients within a floodplain of the River Danube.

    Science.gov (United States)

    Palijan, Goran

    2012-07-01

    This study investigated the relationships of time-dependent hydrological variability and selected microbial food web components. Samples were collected monthly from the Kopački Rit floodplain in Croatia, over a period of 19 months, for analysis of bacterioplankton abundance, cell size and biomass; abundance of heterotrophic nanoflagellates and nanophytoplankton; and concentration of chlorophyll a. Similar hydrological variability at different times of the year enabled partition of seasonal effects from hydrological changes on microbial community properties. The results suggested that, unlike some other studies investigating sites with different connectivity, bacterioplankton abundance, and phytoplankton abundance and biomass increased during lentic conditions. At increasing water level, nanophytoplankton showed lower sensitivity to disturbance in comparison with total phytoplankton biomass: this could prolong autotrophic conditions within the floodplain. Bacterioplankton biomass, unlike phytoplankton, was not impacted by hydrology. The bacterial biomass less affected by hydrological changes can be an important additional food component for the floodplain food web. The results also suggested a mechanism controlling bacterial cell size independent of hydrology, as bacterial cell size was significantly decreased as nanoflagellate abundance increased. Hydrology, regardless of seasonal sucession, has the potential to structure microbial food webs, supporting microbial development during lentic conditions. Conversely, other components appear unaffected by hydrology or may be more strongly controlled by biotic interactions. This research, therefore, adds to understanding on microbial food web interactions in the context of flood and flow pulses in river-floodplain ecosystems.

  8. Congener-specific accumulation and trophic transfer of polychlorinated biphenyls in spider crab food webs revealed by stable isotope analysis

    Energy Technology Data Exchange (ETDEWEB)

    Bodin, N. [IFREMER, DCN-BE, Technopole Brest-Iroise, Pointe du Diable, 29280 Plouzane (France); LPTC-UMR 5472 CNRS, Universite de Bordeaux 1, 351 cours de la Liberation, 33400 Talence (France)], E-mail: bodin.nathalie@caramail.com; Le Loc' h, F. [IRD, UR 070 RAP, Centre de Recherche Halieutique, Avenue Jean Monnet, B.P. 171, 34203 Sete Cedex (France); Caisey, X.; Le Guellec, A.-M.; Abarnou, A.; Loizeau, V. [IFREMER, DCN-BE, Technopole Brest-Iroise, Pointe du Diable, 29280 Plouzane (France); Latrouite, D. [IFREMER, DCB-STH, Technopole Brest-Iroise, Pointe du Diable, 29280 Plouzane (France)

    2008-01-15

    Polychlorobiphenyls (PCB) and stable isotopes ({delta}{sup 15}N and {delta}{sup 13}C) were analyzed in the spider crab (Maja brachydactyla) food web from the Iroise Sea (Western Brittany) and the Seine Bay (Eastern English Channel). PCB concentrations were all significantly higher in organisms from the Seine Bay than those from the Iroise Sea. PCB patterns were strongly related to the feeding mode of the species, and increased influence of higher chlorinated congeners was highlighted with trophic position of the organisms. PCB concentrations (lipid normalized) were significantly related to the isotopically derived trophic level (TL) in spider crab food webs. The highest trophic magnification factors (TMFs) were calculated for the congeners with 2,4,5-substitution, and were lower in the Seine Bay compared to the Iroise Sea. The confrontation of PCB and TL data also revealed biotransformation capacity of decapod crustaceans for specific congeners based on structure-activity relations. - The influence of feeding mode and trophic position on the fate of PCBs in spider crab food webs is discussed by using a stable isotopic approach.

  9. Response of detritus food web and litter quality to elevated CO2 and crop cultivars and their feedback to soil functionality

    Science.gov (United States)

    Hu, Zhengkun; Chen, Xiaoyun; Zhu, Chunwu; Bonkowski, Michael; Hu, Shuijin; Li, Huixin; Hu, Feng; Liu, Manqiang

    2017-04-01

    Elevated atmospheric CO2 concentrations (eCO2) often increase plant growth and alter the belowground detritus soil food web. Interactions with agriculture management may further modify soil process and the associated ecosystem functionality. Little attention, however, has been directed toward assessing the responses of soil food web and their feedback to soil functionality, particularly in wetland agroecosystems. We report results from a long-term free air CO2 enrichment (FACE) experiment in a rice paddy field that examined the responses of detritus food webs to eCO2 (200 ppm higher than ambient CO2 (aCO2)) of two rice cultivars with distinctly weak and strong responses to eCO2. Soil detritus food web components, including soil microbes and microfauna, soil environment as well as resources availability variables, were determined at the rice ripening stage. To obtain the information of soil functionality, indicated by litter decomposition and enzyme activities, we adopted a reciprocal transplant approach that fully manipulate the factors of litter straw and food web components for the incubation of 120 days. Results about the field investigation showed that eCO2 lead to a higher C/N ratio of litter and soil compared to aCO2, especially for the strong responsive cultivar. eCO2-induced enhanced carbon input stimulated the fungal decomposition pathway by increasing fungal biomass, fungi: bacteria ratio and fungivorous nematode. Results from the manipulative incubation experiment showed eCO2-induced lower quality of straw decreased cumulative C mineralization, but changes in detritus food web induced by eCO2 and strongly responsive cultivar lead to an increased CO2 respiration coincidently within each straw type, mainly due to the adaption to the high C/N ratio environment which increased their functional breadth. Based on SEMs and curves of carbon mineralization rate, soil communities showed significant effects on C release at the early stage through mediating enzyme

  10. Biomagnification of persistent organic pollutants in a deep-sea, temperate food web.

    Science.gov (United States)

    Romero-Romero, Sonia; Herrero, Laura; Fernández, Mario; Gómara, Belén; Acuña, José Luis

    2017-12-15

    Polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs) were measured in a temperate, deep-sea ecosystem, the Avilés submarine Canyon (AC; Cantabrian Sea, Southern Bay of Biscay). There was an increase of contaminant concentration with the trophic level of the organisms, as calculated from stable nitrogen isotope data (δ 15 N). Such biomagnification was only significant for the pelagic food web and its magnitude was highly dependent on the type of top predators included in the analysis. The trophic magnification factor (TMF) for PCB-153 in the pelagic food web (spanning four trophic levels) was 6.2 or 2.2, depending on whether homeotherm top predators (cetaceans and seabirds) were included or not in the analysis, respectively. Since body size is significantly correlated with δ 15 N, it can be used as a proxy to estimate trophic magnification, what can potentially lead to a simple and convenient method to calculate the TMF. In spite of their lower biomagnification, deep-sea fishes showed higher concentrations than their shallower counterparts, although those differences were not significant. In summary, the AC fauna exhibits contaminant levels comparable or lower than those reported in other systems. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Cognitive factors affecting free recall, cued recall, and recognition tasks in Alzheimer's disease.

    Science.gov (United States)

    Yamagishi, Takashi; Sato, Takuya; Sato, Atsushi; Imamura, Toru

    2012-01-01

    Our aim was to identify cognitive factors affecting free recall, cued recall, and recognition tasks in patients with Alzheimer's disease (AD). We recruited 349 consecutive AD patients who attended a memory clinic. Each patient was assessed using the Alzheimer's Disease Assessment Scale (ADAS) and the extended 3-word recall test. In this task, each patient was asked to freely recall 3 previously presented words. If patients could not recall 1 or more of the target words, the examiner cued their recall by providing the category of the target word and then provided a forced-choice recognition of the target word with 2 distracters. The patients were divided into groups according to the results of the free recall, cued recall, and recognition tasks. Multivariate logistic regression analysis for repeated measures was carried out to evaluate the net effects of cognitive factors on the free recall, cued recall, and recognition tasks after controlling for the effects of age and recent memory deficit. Performance on the ADAS Orientation task was found to be related to performance on the free and cued recall tasks, performance on the ADAS Following Commands task was found to be related to performance on the cued recall task, and performance on the ADAS Ideational Praxis task was found to be related to performance on the free recall, cued recall, and recognition tasks. The extended 3-word recall test reflects deficits in a wider range of memory and other cognitive processes, including memory retention after interference, divided attention, and executive functions, compared with word-list recall tasks. The characteristics of the extended 3-word recall test may be advantageous for evaluating patients' memory impairments in daily living.

  12. Web-based information system design of agricultural management towards self-sufficiency local food in North Aceh

    Science.gov (United States)

    Salahuddin; Husaini; Anwar

    2018-01-01

    The agricultural sector, especially food crops and horticulture, is one of the sectors driving regional economic pillars in Aceh Utara Regency of Aceh Province. Some agricultural products and food crops that become excellent products in North Aceh regency are: rice, corn, peanuts, long beans, cassava and soybeans. The Local Government of North Aceh Regency has not been optimal in empowering and maximizing the potential of agriculture resources. One of the obstacles is caused by the North Aceh Regency Government does not have an adequate database and web information system/GIS (Geographic Information System) for data management of agricultural centre in North Aceh Regency. This research is expected to assist local government of North Aceh Regency in managing agriculture sector to realize local food independence the region in supporting national food security program. The method in this research is using waterfall method for designing and making information system by conducting sequential process starting from data collection stage, requirement analysis, design, coding, testing and implementation system. The result of this research is a web-based information system for the management of agriculture superior agricultural product centre in North Aceh. This application provides information mapping the location of agricultural superior product producers and mapping of potential locations for the development of certain commodities in North Aceh Regency region in realizing food self-sufficiency in the region.

  13. Spatial scales of carbon flow in a river food web

    Science.gov (United States)

    Finlay, J.C.; Khandwala, S.; Power, M.E.

    2002-01-01

    Spatial extents of food webs that support stream and river consumers are largely unknown, but such information is essential for basic understanding and management of lotic ecosystems. We used predictable variation in algal ??13C with water velocity, and measurements of consumer ??13C and ??15N to examine carbon flow and trophic structure in food webs of the South Fork Eel River in Northern California. Analyses of ??13C showed that the most abundant macroinvertebrate groups (collector-gatherers and scrapers) relied on algae from local sources within their riffle or shallow pool habitats. In contrast, filter-feeding invertebrates in riffles relied in part on algal production derived from upstream shallow pools. Riffle invertebrate predators also relied in part on consumers of pool-derived algal carbon. One abundant taxon drifting from shallow pools and riffles (baetid mayflies) relied on algal production derived from the habitats from which they dispersed. The trophic linkage from pool algae to riffle invertebrate predators was thus mediated through either predation on pool herbivores dispersing into riffles, or on filter feeders. Algal production in shallow pool habitats dominated the resource base of vertebrate predators in all habitats at the end of the summer. We could not distinguish between the trophic roles of riffle algae and terrestrial detritus, but both carbon sources appeared to play minor roles for vertebrate consumers. In shallow pools, small vertebrates, including three-spined stickleback (Gasterosteus aculeatus), roach (Hesperoleucas symmetricus), and rough-skinned newts (Taricha granulosa), relied on invertebrate prey derived from local pool habitats. During the most productive summer period, growth of all size classes of steelhead and resident rainbow trout (Oncorhynchus mykiss) in all habitats (shallow pools, riffles, and deep unproductive pools) was largely derived from algal production in shallow pools. Preliminary data suggest that the strong

  14. Rotifer fecundity in relation to components of microbial food web in a eurotrophic reservoir

    Czech Academy of Sciences Publication Activity Database

    Devetter, Miloslav; Seďa, Jaromír

    2003-01-01

    Roč. 504, - (2003), s. 167-175 ISSN 0018-8158. [Reservoir Limnology and Water Quality /4./. České Budějovice, 12.08.2002-16.08.2002] Institutional research plan: CEZ:AV0Z6017912 Keywords : rotifers * microbial food web Subject RIV: EH - Ecology, Behaviour Impact factor: 0.720, year: 2003

  15. Common Modality Effects in Immediate Free Recall and Immediate Serial Recall

    Science.gov (United States)

    Grenfell-Essam, Rachel; Ward, Geoff; Tan, Lydia

    2017-01-01

    In 2 experiments, participants were presented with lists of between 2 and 12 words for either immediate free recall (IFR) or immediate serial recall (ISR). Auditory recall advantages at the end of the list (modality effects) and visual recall advantages early in the list (inverse modality effects) were observed in both tasks and the extent and…

  16. Soil resource supply influences faunal size?specific distributions in natural food webs

    OpenAIRE

    Mulder, Christian; Den Hollander, Henri A.; Vonk, J. Arie; Rossberg, Axel G.; Jagers op Akkerhuis, Gerard A. J. M.; Yeates, Gregor W.

    2009-01-01

    The large range of body-mass values of soil organisms provides a tool to assess the ecological organization of soil communities. The goal of this paper is to identify graphical and quantitative indicators of soil community composition and ecosystem functioning, and to illustrate their application to real soil food webs. The relationships between log-transformed mass and abundance of soil organisms in 20 Dutch meadows and heathlands were investigated. Using principles of allometry, maximal use...

  17. Changes in food web structure and ecosystem functioning of a large, shallow Chinese lake during the 1950s, 1980s and 2000s

    DEFF Research Database (Denmark)

    Kong, Xiangzhen; He, Wei; Liu, Wenxiu

    2016-01-01

    that hydrological regulation may play a significant role in driving all of these changes in Lake Chaohu in addition to eutrophication and intensive fishery. Overall, we strongly advocate the identification of a threshold in abundance of zooplanktivorous fish, an integrated strategy for future ecological restoration......Food web structure dynamics and ecosystem functioning are strongly linked, and both are indispensable in evaluating ecosystem development in lakes under multiple anthropogenic stressors. However, model-based approaches concerning the changes in food web structure and ecosystem functioning...... validated by the stable isotope-determined trophic level (TL) for each functional group, which indicated an acceptable model performance. Over time, we observed a collapse of the food web toward a simplified structure and decreasing biodiversity and trophic interactions. The lake ecosystem was approaching...

  18. How does litter quality and site heterogeneity interact on decomposer food webs of a semi-natural forest?

    DEFF Research Database (Denmark)

    Strandmark, Lisa Bjørnlund; Christensen, Søren

    2005-01-01

    The relative importance of litter quality and site heterogeneity on population dynamics of decomposer food webs was investigated in a semi-natural mixed deciduous forest in Denmark. Litterbags containing beech or ash leaves were placed in four plots. Plots were located within gaps and under closed...... at the end of the study period. At the first sampling, where bacterial activity prevailed, the relative abundance of the two dominant bacterial-feeders, Rhabditidae (fast growing) and Plectus spp. (slower growing), depended more on site than litter type. At the second sampling where fungal activity became...... in the decomposer food web, site effects were also detected and nematode functional groups responded more to site than to litter quality early on in the decomposition process....

  19. WebDASC: a web-based dietary assessment software for 8-11-year-old Danish children

    DEFF Research Database (Denmark)

    Biltoft-Jensen, Anja Pia; Trolle, Ellen; Christensen, Tue

    , literature review, and usability tests preceded its release. Special consideration was given to age-appropriate design issues. Results:  In WebDASC an animated armadillo guides respondents through six daily eating occasions and helps them report foods and beverages previously consumed. A database of 1300...... food items is available either through category browse or free text search, aided by a spell check application. A type-in format is available for foods not otherwise found through category browse or text search. Amount consumed is estimated by selecting the closest portion size among four different...... digital images. WebDASC includes internal checks for frequently forgotten foods, and the following features to create motivation: a food-meter displaying cumulative weight of foods reported, a most popular food ranking, and a computer game with a high score list. Conclusions:  WebDASC was developed...

  20. Some lower food web organisms in the nutrition of marine harpacticoid copepods: an experimental study

    Science.gov (United States)

    Rieper, Marianna

    1985-12-01

    Some lower food web organisms from the marine littoral environment were studied as food for harpacticoid copepods. In laboratory experiments, it could be shown that, among the ciliates, the slow-moving Uronema sp. was taken up while the fast-moving Euplotes sp. was not. Asterionella glacialis, a pennate diatom with spiny projections, was unsuitable as food. The centric diatom Skeletonema costatum was ingested by all harpacticoid species tested, including Tisbe holothuriae, Paramphiascella vararensis, Amphiascoides debilis and Dactylopodia vulgaris. All are epibenthic and phytal species occurring in the shallow waters of Helgoland (North Sea). The amount of ciliate and algal carbon taken up was less than that provided by bacteria under laboratory conditions. However, some diatom food may be essential for the development of D. vulgaris.

  1. Zinc isotope ratios of bones and teeth as new dietary indicators: results from a modern food web (Koobi Fora, Kenya)

    OpenAIRE

    Jaouen, Klervia; Beasley, Melanie; Schoeninger, Margaret; Hublin, Jean-Jacques; Richards, Michael P.

    2016-01-01

    In order to explore the possibilities of using zinc (Zn) stable isotope ratios as dietary indicators, we report here on the measurements of the ratio of stable isotopes of zinc (66Zn/64Zn, expressed here as ?66Zn) in bioapatite (bone and dental enamel) of animals from a modern food web in the Koobi Fora region of the Turkana Basin in Kenya. We demonstrate that ?66Zn values in both bone and enamel allow a clear distinction between carnivores and herbivores from this food web. Differences were ...

  2. Examining the relationship between free recall and immediate serial recall: the serial nature of recall and the effect of test expectancy.

    Science.gov (United States)

    Bhatarah, Parveen; Ward, Geoff; Tan, Lydia

    2008-01-01

    In two experiments, we examined the relationship between free recall and immediate serial recall (ISR), using a within-subjects (Experiment 1) and a between-subjects (Experiment 2) design. In both experiments, participants read aloud lists of eight words and were precued or postcued to respond using free recall or ISR. The serial position curves were U-shaped for free recall and showed extended primacy effects with little or no recency for ISR, and there was little or no difference between recall for the precued and the postcued conditions. Critically, analyses of the output order showed that although the participants started their recall from different list positions in the two tasks, the degree to which subsequent recall was serial in a forward order was strikingly similar. We argue that recalling in a serial forward order is a general characteristic of memory and that performance on ISR and free recall is underpinned by common memory mechanisms.

  3. Assimilation of aged organic carbon in a glacial river food web

    Science.gov (United States)

    Fellman, J.; Hood, E. W.; Raymond, P. A.; Bozeman, M.; Hudson, J.; Arimitsu, M.

    2013-12-01

    Identifying the key sources of organic carbon supporting fish and invertebrate consumers is fundamental to our understanding of stream ecosystems. Recent laboratory bioassays highlight that aged organic carbon from glacier environments is highly bioavailable to stream bacteria relative to carbon originating from ice-free areas. However, there is little evidence suggesting that this aged, bioavailable organic carbon is also a key basal carbon source for stream metazoa. We used natural abundance of Δ14C, δ13C, and δ15N to determine if fish and invertebrate consumers are subsidized by aged organic carbon in a glacial river in southeast Alaska. We collected biofilm, leaf litter, three different species of macroinvertebrates, and resident juvenile salmonids from a reference stream and two sites (one site is directly downstream of the glacial outflow and one site is upstream of the tidal estuary) on the heavily glaciated Herbert River. Key producers, fish, and invertebrate consumers in the reference stream had carbon isotope values that ranged from -26 to -30‰ for δ13C and from -12 to 53‰ for Δ14C, reflecting a food web sustained mainly on contemporary primary production. In contrast, biofilm in the two glacial sites was highly Δ14C depleted (-203 to -215‰) relative to the reference site. Although biofilm may consist of both bacteria and benthic algae utilizing carbon depleted in Δ14C, δ13C values for biofilm (-24.1‰), dissolved inorganic carbon (-5.9‰), and dissolved organic carbon (-24.0‰) suggest that biofilm consist of bacteria sustained in part by glacier-derived, aged organic carbon. Invertebrate consumers (mean Δ14C of -80.5, mean δ13C of -26.5) and fish (mean Δ14C of -63.3, mean δ13C of -25.7) in the two glacial sites had carbon isotope values similar to biofilm. These results similarly show that aged organic carbon is incorporated into the metazoan food web. Overall, our findings indicate that continued watershed deglaciation and

  4. Combined effects of global climate change and regional ecosystem drivers on an exploited marine food web

    DEFF Research Database (Denmark)

    Niiranen, S.; Yletyinen, J.; Tomczak, M.T.

    2013-01-01

    approach to project how the interaction of climate, nutrient loads, and cod fishing may affect the future of the open Central Baltic Sea food web. Regionally downscaled global climate scenarios were, in combination with three nutrient load scenarios, used to drive an ensemble of three regional...... biogeochemical models (BGMs). An Ecopath with Ecosim food web model was then forced with the BGM results from different nutrient-climate scenarios in combination with two different cod fishing scenarios. The results showed that regional management is likely to play a major role in determining the future......Changes in climate, in combination with intensive exploitation of marine resources, have caused large-scale reorganizations in many of the world's marine ecosystems during the past decades. The Baltic Sea in Northern Europe is one of the systems most affected. In addition to being exposed...

  5. To Everything There Is a Season: Summer-to-Winter Food Webs and the Functional Traits of Keystone Species.

    Science.gov (United States)

    Humphries, Murray M; Studd, Emily K; Menzies, Allyson K; Boutin, Stan

    2017-11-01

    From a trophic perspective, a seasonal increase in air temperature and photoperiod propagates as bottom-up pulse of primary production by plants, secondary production by herbivores, and tertiary production by carnivores. However, food web seasonality reflects not only abiotic variation in temperature and photoperiod, but also the composition of the biotic community and their functional responses to this variation. Some plants and animals-here referred to as seasonal specialists-decouple from food webs in winter through migration or various forms of metabolic arrest (e.g., senescence, diapause, and hibernation), whereas some plants and resident animals-here referred to as seasonal generalists-remain present and trophically coupled in winter. The co-occurrence of species with divergent responses to winter introduces seasonal variation in interaction strengths, resulting in summer-to-winter differences in trophic organization. Autumn cooling and shortening day length arrests primary productivity and cues seasonal herbivores to decouple, leaving generalist carnivores to concentrate their predation on the few generalist herbivores that remain resident, active, and vulnerable to predation in winter, which themselves feed on the few generalist plant structures available in winter. Thus, what was a bottom-up pulse, spread among many species in summer, including highly productive seasonal specialists, reverses into strong top-down regulation in winter that is top-heavy, and concentrated among a small number of generalist herbivores and their winter foods. Intermediate-sized, generalist herbivores that remain active and vulnerable to predation in winter are likely to be keystone species in seasonal food webs because they provide the essential ecosystem service of turning summer primary productivity into winter food for carnivores. Empirical examination of terrestrial mammals and their seasonal trophic status in the boreal forest and across an arctic-to-tropics seasonality

  6. Trophic state changes can affect the importance of methane-derived carbon in aquatic food webs

    NARCIS (Netherlands)

    Schilder, Jos; Van Hardenbroek, M.; Bodelier, P.L.E.; Kirilova, Emiliya P.; Leuenberger, Markus; Lotter, A.F.; Heiri, O.

    2017-01-01

    Methane-derived carbon, incorporated by methane-oxidizing bacteria, has been identified as a significant source of carbon in food webs of many lakes. By measuring the stable carbon isotopic composition (δ13C values) of particulate organic matter, Chironomidae and Daphnia spp. and their resting eggs

  7. Validity of dietary recall over 20 years among California Seventh-day Adventists.

    Science.gov (United States)

    Fraser, G E; Lindsted, K D; Knutsen, S F; Beeson, W L; Bennett, H; Shavlik, D J

    1998-10-15

    Past dietary habits are etiologically important to incident disease. Yet the validity of such measurements from the previous 10-20 years is poorly understood. In this study, the authors correlated food frequency results that were obtained in 1994-1995 but pertained to recalled diet in 1974 with the weighted mean of five random 24-hour dietary recalls obtained by telephone in 1974. The subjects studied were 72 Seventh-day Adventists who lived within 30 miles of Loma Linda, California; had participated in a 1974 validation study; were still alive; and were willing to participate again in 1994. A method was developed to allow correction for random error in the reference data when these data had differentially weighted components. The results showed partially corrected correlation coefficients of greater than 0.30 for coffee, whole milk, eggs, chips, beef, fish, chicken, fruit, and legumes. Higher correlations on average were obtained when the food frequencies were scored simply 1-9, reflecting the nine frequency categories. The 95% confidence intervals for 15 of the 28 correlations excluded zero. Incorporation of portion size information was unhelpful. The authors concluded that in this population, data recalled from 20 years ago should be treated with caution but, for a number of important foods, that the degree of validity achieved approached that obtained when assessing current dietary habits.

  8. Feasibility of 2 × 24-h dietary recalls combined with a food-recording booklet, using EPIC-Soft, among schoolchildren.

    Science.gov (United States)

    Trolle, E; Amiano, P; Ege, M; Bower, E; Lioret, S; Brants, H; Kaic-Rak, A; de Boer, E J; Andersen, L F

    2011-07-01

    The aim of this study was to evaluate the feasibility of the suggested trans-European methodology for undertaking representative dietary surveys among schoolchildren: 2 × 24-h dietary recalls (24-HDRs) combined with a food-recording booklet, using EPIC-Soft (the software developed to conduct 24-HDRs in the European Prospective Investigation into Cancer and Nutrition (EPIC) Study) pc-program. A total of 75 children aged 7-8 years and 70 children aged 12-13 years old were recruited through the Civil Registration System in Denmark, and 57 children aged 7-8 years and 47 children aged 12-13 years were recruited through schools in Spain. Each child with one parent completed two face-to-face 24-HDRs, combined with optional use of a food-recording booklet (FRB) to be filled in by the child, a parent or other proxy persons for preparing the recalls. Feasibility was evaluated by questionnaires completed by parents, children and interviewers, and by selected data from the 24-HDRs. The face-to-face interviews with the child and a parent together are confirmed as feasible. The children participated actively in the interviews, the oldest children being most active. The children, parents and interviewers agreed that children needed help from the parents, and that parents were of help to the child. In both countries, other proxy persons, such as teachers or the school cafeteria staff, were involved before the interview, and the majority of the parents and children reported that the FRB had been a help for the child during the interview. Further results point at specific needed improvements of the tools. The evaluated method is shown feasible in two culturally diverse European populations. However, the feasibility study also points to specific improvements of tools and data collection protocol that are strongly recommended before implementation of the method in each country of a pan-European dietary survey.

  9. Highly resolved early Eocene food webs show development of modern trophic structure after the end-Cretaceous extinction

    OpenAIRE

    Dunne, Jennifer A.; Labandeira, Conrad C.; Williams, Richard J.

    2014-01-01

    Generalities of food web structure have been identified for extant ecosystems. However, the trophic organization of ancient ecosystems is unresolved, as prior studies of fossil webs have been limited by low-resolution, high-uncertainty data. We compiled highly resolved, well-documented feeding interaction data for 700 taxa from the 48 million-year-old latest early Eocene Messel Shale, which contains a species assemblage that developed after an interval of protracted environmental and biotal c...

  10. Effects of genetically modified maize events expressing Cry34Ab1, Cry35Ab1, Cry1F, and CP4 EPSPS proteins on arthropod complex food webs.

    Science.gov (United States)

    Pálinkás, Zoltán; Kiss, József; Zalai, Mihály; Szénási, Ágnes; Dorner, Zita; North, Samuel; Woodward, Guy; Balog, Adalbert

    2017-04-01

    Four genetically modified (GM) maize ( Zea mays L.) hybrids (coleopteran resistant, coleopteran and lepidopteran resistant, lepidopteran resistant and herbicide tolerant, coleopteran and herbicide tolerant) and its non-GM control maize stands were tested to compare the functional diversity of arthropods and to determine whether genetic modifications alter the structure of arthropods food webs. A total number of 399,239 arthropod individuals were used for analyses. The trophic groups' number and the links between them indicated that neither the higher magnitude of Bt toxins (included resistance against insect, and against both insects and glyphosate) nor the extra glyphosate treatment changed the structure of food webs. However, differences in the average trophic links/trophic groups were detected between GM and non-GM food webs for herbivore groups and plants. Also, differences in characteristic path lengths between GM and non-GM food webs for herbivores were observed. Food webs parameterized based on 2-year in-field assessments, and their properties can be considered a useful and simple tool to evaluate the effects of Bt toxins on non-target organisms.

  11. Estuarine consumers utilize marine, estuarine and terrestrial organic matter and provide connectivity among these food webs

    Science.gov (United States)

    The flux of organic matter (OM) across ecosystem boundaries can influence estuarine food web dynamics and productivity. However, this process is seldom investigated taking into account all the adjacent ecosystems (e.g. ocean, river, land) and different hydrological settings (i.e....

  12. Effects of aggregation pheromone on individual behaviour and food web interactions: a field study on Drosophila

    NARCIS (Netherlands)

    Wertheim, B.; Allemand, R.; Vet, L.E.M.; Dicke, M.

    2006-01-01

    The effects of an aggregation pheromone on individual behaviour and food web interactions were investigated in two ecological communities, using Drosophila melanogaster and D. simulans as focal species. 2. Fruit substrates with aggregation pheromone were significantly more attractive to adult D.

  13. Recalls API

    Data.gov (United States)

    US Consumer Product Safety Commission — CPSC provides accessibility to recalls via a recall database. The information is publicly available to consumers and businesses as well as software and application...

  14. Are forward and backward recall the same? A dual-task study of digit recall.

    Science.gov (United States)

    St Clair-Thompson, Helen L; Allen, Richard J

    2013-05-01

    There is some debate surrounding the cognitive resources underlying backward digit recall. Some researchers consider it to differ from forward digit recall due to the involvement of executive control, while others suggest that backward recall involves visuospatial resources. Five experiments therefore investigated the role of executive-attentional and visuospatial resources in both forward and backward digit recall. In the first, participants completed visuospatial 0-back and 2-back tasks during the encoding of information to be remembered. The concurrent tasks did not differentially disrupt performance on backward digit recall, relative to forward digit recall. Experiment 2 shifted concurrent load to the recall phase instead and, in this case, revealed a larger effect of both tasks on backward recall, relative to forwards recall, suggesting that backward recall may draw on additional resources during the recall phase and that these resources are visuospatial in nature. Experiments 3 and 4 then further investigated the role of visual processes in forward and backward recall using dynamic visual noise (DVN). In Experiment 3, DVN was presented during encoding of information to be remembered and had no effect upon performance. However, in Experiment 4, it was presented during the recall phase, and the results provided evidence of a role for visual imagery in backward digit recall. These results were replicated in Experiment 5, in which the same list length was used for forward and backward recall tasks. The findings are discussed in terms of both theoretical and practical implications.

  15. Iranian Television Advertisement and Children's Food Preferences.

    Science.gov (United States)

    Hajizadehoghaz, Masoomeh; Amini, Maryam; Abdollahi, Afsoun

    2016-01-01

    In this study, the nature of food commercials in children's television (TV) was monitored and analyzed; simultaneously, the relationship between recalling TV food commercials and children's interest in them and in the consumption of the same food products was evaluated. A total of 108 h children's programs broadcast on two channels (Two and Amouzesh) of Islamic Republic of Iran Broadcasting (IRIB) media organization were monitored (May 6-12, 2015). Simultaneously, a cross-sectional study using 403 primary schoolchildren (201 boys) in four schools of Shirvan, Northeast of Iran, was executed. The children were prompted to recall all TV commercials broadcast on IRIB. Meanwhile, they were directed to define in the list of recalled TV food commercials those were interested in and the commercials (food products) they actually were willing to consume. Regarding the frequency and duration of broadcasting, food commercials ranked fifth and sixth, respectively. Fruit leather and plum paste were the most frequently broadcast food commercials. "High quality" (19%), "good taste" (15%), "novelty", and "message on nutritional composition" (13%) were the most frequent messages used in promoting the sale of food products, respectively. In addition, focus on "high quality/precision in the preparation of the food products" was the most frequently used appeals in TV commercials. There was a significant relationship between recalling TV food commercials and the interest in five out of eight of the commercials (62.5%) ( P TV food commercials and the interest in the consumption of the same food product ("Tomato paste B") was statistically significant for 12.5% of the commercials ( P TV food commercials do not encourage healthy eating. The current study provides convincing evidence for policy-makers and researchers to pay more attention to this area.

  16. Effects of aggregation pheromone on individual behaviour and food web interactions : A field study on Drosophila

    NARCIS (Netherlands)

    Wertheim, Bregje; Allemand, Roland; Vet, Louise E. M.; Dicke, Marcel

    1. The effects of an aggregation pheromone on individual behaviour and food web interactions were investigated in two ecological communities, using Drosophila melanogaster and D. simulatis as focal species. 2. Fruit substrates with aggregation pheromone were significantly more attractive to adult D.

  17. Cognitive Factors Affecting Free Recall, Cued Recall, and Recognition Tasks in Alzheimer’s Disease

    Directory of Open Access Journals (Sweden)

    Takashi Yamagishi

    2012-07-01

    Full Text Available Background/Aims: Our aim was to identify cognitive factors affecting free recall, cued recall, and recognition tasks in patients with Alzheimer’s disease (AD. Subjects: We recruited 349 consecutive AD patients who attended a memory clinic. Methods: Each patient was assessed using the Alzheimer’s Disease Assessment Scale (ADAS and the extended 3-word recall test. In this task, each patient was asked to freely recall 3 previously presented words. If patients could not recall 1 or more of the target words, the examiner cued their recall by providing the category of the target word and then provided a forced-choice recognition of the target word with 2 distracters. The patients were divided into groups according to the results of the free recall, cued recall, and recognition tasks. Multivariate logistic regression analysis for repeated measures was carried out to evaluate the net effects of cognitive factors on the free recall, cued recall, and recognition tasks after controlling for the effects of age and recent memory deficit. Results: Performance on the ADAS Orientation task was found to be related to performance on the free and cued recall tasks, performance on the ADAS Following Commands task was found to be related to performance on the cued recall task, and performance on the ADAS Ideational Praxis task was found to be related to performance on the free recall, cued recall, and recognition tasks. Conclusion: The extended 3-word recall test reflects deficits in a wider range of memory and other cognitive processes, including memory retention after interference, divided attention, and executive functions, compared with word-list recall tasks. The characteristics of the extended 3-word recall test may be advantageous for evaluating patients’ memory impairments in daily living.

  18. Carbon and nitrogen flows through the benthic food web of a photic subtidal sandy sediment

    NARCIS (Netherlands)

    Evrard, V.P.E.; Soetaert, K.E.R.; Heip, C.H.R.; Huettel, M.; Xenopoulos, M.A.; Middelburg, J.J.

    2010-01-01

    Carbon and nitrogen flows within the food web of a subtidal sandy sediment were studied using stable isotope natural abundances and tracer addition. Natural abundances of 13C and 15N stable isotopes of the consumers and their potential benthic and pelagic resources were measured. δ13C data revealed

  19. Tracing salmon-derived nutrients and contaminants in freshwater food webs across a pronounced spawner density gradient.

    Science.gov (United States)

    Gregory-Eaves, Irene; Demers, J Marc J; Kimpe, Lynda; Krümmel, Eva M; Macdonald, Robie W; Finney, Bruce P; Blais, Jules M

    2007-06-01

    Many have demonstrated that anadromous Pacific salmon are significant vectors of nutrients from the ocean to freshwaters. Recently. however, it has been recognized that salmon spawners also input significant quantities of contaminants. The objectives of this paper are to delineate the extent to which salmon-derived nutrients are integrated into the freshwater food web using delta(15)N and delta(13)C and to assess the influence of the salmon pathway in the accumulation of contaminants in rainbow trout (Oncorhynchus mykiss). We found that the delta(15)N and delta(13)C of food web components were related positively and significantly to sockeye salmon (Oncorhynchus nerka) spawner density. Contaminant concentrations in rainbow trout also positively and significantly were related to sockeye salmon spawner density. These data suggest that the anadromous salmon nutrient and contaminant pathways are related and significantly impact the contaminant burden of resident fish.

  20. Iterative Development of an Online Dietary Recall Tool: INTAKE24

    Directory of Open Access Journals (Sweden)

    Emma Simpson

    2017-02-01

    Full Text Available Collecting large-scale population data on dietary intake is challenging, particularly when resources and funding are constrained. Technology offers the potential to develop novel ways of collecting large amounts of dietary information while making it easier, more convenient, intuitive, and engaging for users. INTAKE24 is an online multiple pass 24 h dietary recall tool developed for use in national food and nutrition surveys. The development of INTAKE24 was a four-stage iterative process of user interaction and evaluation with the intended end users, 11–24 years old. A total of 80 11–24 years old took part in the evaluation, 20 at each stage. Several methods were used to elicit feedback from the users including, ‘think aloud’, ‘eye tracking’, semi-structured interviews, and a system usability scale. Each participant completed an interviewer led recall post system completion. Key system developments generated from the user feedback included a ‘flat’ interface, which uses only a single interface screen shared between all of the various activities (e.g., free text entry, looking up foods in the database, portion size estimation. Improvements to the text entry, search functionality, and navigation around the system were also influenced through feedback from users at each stage. The time to complete a recall using INTAKE24 almost halved from the initial prototype to the end system, while the agreement with an interviewer led recall improved. Further developments include testing the use of INTAKE24 with older adults and translation into other languages for international use. Our future aim is to validate the system with recovery biomarkers.

  1. An isotopic investigation of mercury accumulation in terrestrial food webs adjacent to an Arctic seabird colony

    International Nuclear Information System (INIS)

    Choy, Emily S.; Gauthier, Martine; Mallory, Mark L.; Smol, John P.; Douglas, Marianne S.V.; Lean, David; Blais, Jules M.

    2010-01-01

    At Cape Vera (Devon Island, Nunavut, Canada), a seabird colony of northern fulmars (Fulmarus glacialis) congregates and releases nutrients through the deposition of guano to the coastal terrestrial environment, thus creating nutrient-fertilized habitats important to insects, birds, and mammals. Here we determined whether mercury was similarly enriched in various terrestrial food web components in this High Arctic coastal ecosystem due to seabird inputs. Stable isotopes (δ 15 N, δ 13 C) were used to identify trophic linkages and possible routes of contaminant transfer in the food web. Values of δ 15 N were significantly higher in lichens and certain plants collected closer to the bird colony, demonstrating a gradient of seabird influence, and were higher at Cape Vera than our reference site at Cape Herschel, on eastern Ellesmere Island, an area relatively unaffected by seabirds. In contrast, δ 13 C showed little variation among terrestrial species, suggesting minimal influence by seabirds. Concentrations of total mercury (THg) in primary producers and phyto/zooplankton were not significantly correlated with distance from the seabird colony or δ 15 N values, and were similar to other taxa from the High Arctic. Our results provide novel data on THg in several Arctic taxa where concentrations have not been reported previously. Moreover, the analyses indicate that δ 15 N is significantly enriched in the adjacent environment by guano fertilization, but our study was unable to show an enrichment of THg and δ 13 C in the terrestrial food web near the seabird colony.

  2. Food Web Structure and Basal Resource Utilization along a Tropical Island Stream Continuum, Puerto Rico.

    Science.gov (United States)

    James G. March; Catherine M. Pringle

    2003-01-01

    Tropical stream food webs are thought to be based primarily on terrestrial resources (leaf litter) in small forested headwater streams and algal resources in larger, wider streams. In tropical island streams, the dominant consumers are often omnivorous freshwater shrimps that consume algae, leaf litter, insects, and other shrimps. We used stable isotope analysis...

  3. Characteristics of fast-food/takeaway-food and restaurant/café-food consumers among New Zealand adults.

    Science.gov (United States)

    Smith, Claire; Gray, Andrew Robert; Fleming, Elizabeth Ann; Parnell, Winsome Ruth

    2014-10-01

    To investigate: (i) the percentage of the New Zealand (NZ) population reporting fast food/takeaway food and restaurant/café food per day; (ii) examine demographic factors associated with their use; (iii) quantify their contribution to energy intake; and (iv) describe the specific types of foods reported from both sources. Twenty-four hour diet recalls from the cross-sectional 2008/09 NZ Adult Nutrition Survey were used to identify fast-food and restaurant-food consumers. NZ households. Adults aged 15 years and older (n 4721). Overall 28 % reported consuming at least one fast food and 14 % a restaurant food within the 24 h diet recall. Fast-food consumption was not associated with level of education or an area-based measure of socio-economic status, but a higher education was positively associated with restaurant-food consumption. Individual factors such as ethnicity, household size, age, sex and marital status were found to be important influences on the use of fast food and restaurant food. Fast-food consumption was more prevalent among participants living in urban areas, young adults (19-30 years) and Māori compared with NZ European and Others. The most frequently reported fast foods were bread-based dishes, potatoes (including fries) and non-alcoholic beverages. Given the high reported consumption of fast food by young adults, health promotion initiatives both to improve the nutritional quality of fast-food menus and to encourage healthier food choices would likely make a large impact on the overall diet quality of this group.

  4. Smartphone tool to collect repeated 24 h dietary recall data in Nepal.

    Science.gov (United States)

    Harris-Fry, Helen; Beard, B James; Harrisson, Tom; Paudel, Puskar; Shrestha, Niva; Jha, Sonali; Shrestha, Bhim P; Manandhar, Dharma S; Costello, Anthony; Saville, Naomi M

    2018-02-01

    To outline the development of a smartphone-based tool to collect thrice-repeated 24 h dietary recall data in rural Nepal, and to describe energy intakes, common errors and researchers' experiences using the tool. We designed a novel tool to collect multi-pass 24 h dietary recalls in rural Nepal by combining the use of a CommCare questionnaire on smartphones, a paper form, a QR (quick response)-coded list of foods and a photographic atlas of portion sizes. Twenty interviewers collected dietary data on three non-consecutive days per respondent, with three respondents per household. Intakes were converted into nutrients using databases on nutritional composition of foods, recipes and portion sizes. Dhanusha and Mahottari districts, Nepal. Pregnant women, their mothers-in-law and male household heads. Energy intakes assessed in 150 households; data corrections and our experiences reported from 805 households and 6765 individual recalls. Dietary intake estimates gave plausible values, with male household heads appearing to have higher energy intakes (median (25th-75th centile): 12 079 (9293-14 108) kJ/d) than female members (8979 (7234-11 042) kJ/d for pregnant women). Manual editing of data was required when interviewers mistook portions for food codes and for coding items not on the food list. Smartphones enabled quick monitoring of data and interviewer performance, but we initially faced technical challenges with CommCare forms crashing. With sufficient time dedicated to development and pre-testing, this novel smartphone-based tool provides a useful method to collect data. Future work is needed to further validate this tool and adapt it for other contexts.

  5. Trophic transfer of microplastics and mixed contaminants in the marine food web and implications for human health.

    Science.gov (United States)

    Carbery, Maddison; O'Connor, Wayne; Palanisami, Thavamani

    2018-06-01

    Plastic litter has become one of the most serious threats to the marine environment. Over 690 marine species have been impacted by plastic debris with small plastic particles being observed in the digestive tract of organisms from different trophic levels. The physical and chemical properties of microplastics facilitate the sorption of contaminants to the particle surface, serving as a vector of contaminants to organisms following ingestion. Bioaccumulation factors for higher trophic organisms and impacts on wider marine food webs remain unknown. The main objectives of this review were to discuss the factors influencing microplastic ingestion; describe the biological impacts of associated chemical contaminants; highlight evidence for the trophic transfer of microplastics and contaminants within marine food webs and outline the future research priorities to address potential human health concerns. Controlled laboratory studies looking at the effects of microplastics and contaminants on model organisms employ nominal concentrations and consequently have little relevance to the real environment. Few studies have attempted to track the fate of microplastics and mixed contaminants through a complex marine food web using environmentally relevant concentrations to identify the real level of risk. To our knowledge, there has been no attempt to understand the transfer of microplastics and associated contaminants from seafood to humans and the implications for human health. Research is needed to determine bioaccumulation factors for popular seafood items in order to identify the potential impacts on human health. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. Mercury and selenium biomagnification in a Brazilian coastal food web using nitrogen stable isotope analysis: A case study in an area under the influence of the Paraiba do Sul River plume

    International Nuclear Information System (INIS)

    Kehrig, Helena A.; Seixas, Tercia G.; Malm, Olaf; Di Beneditto, Ana Paula M.; Rezende, Carlos E.

    2013-01-01

    Highlights: • Cetacean and voracious fish displayed similar δ 15 N values. • Cetacean displayed higher Hg and lower Se than voracious fish. • Hg showed an elevated biomagnification power over the entire tropical food web. • Se biomagnified in lower and intermediate trophic positions. • Five trophic positions were found in relation to primary consumer as baseline. -- Abstract: Mercury (Hg), selenium (Se) and nitrogen (δ 15 N) stable isotope were assessed in a tropical food web of Rio de Janeiro’s north coast. Isotopic data on muscle suggest a difference related to this parameter along the food web; where top-predators (cetacean and voracious fish) displayed heavier δ 15 N over the entire food web. Both top-predators presented similar δ 15 N values. Cetacean displayed higher Hg and lower Se than voracious fish. Five trophic positions (TP) were found in relation to primary consumer as baseline, ranging from 2.0 to 4.0. Positive relationships were found between trace-element and δ 15 N. The slope of regression equations (0.11 for Se and 0.21 for Hg) and food web magnification factors (2.4 for Se and 5.4 for Hg) showed that Hg presented higher rate of increase over the food web. Simultaneous measurements of trace-elements and ecological tracers emphasize the importance of TP into the trophic structure and distribution of Hg and Se throughout the food web

  7. Fatty acid composition at the base of aquatic food webs is influenced by habitat type and watershed land use

    Science.gov (United States)

    Larson, James H.; Richardson, William B.; Knights, Brent C.; Bartsch, Lynn; Bartsch, Michelle; Nelson, J. C.; Veldboom, Jason A.; Vallazza, Jonathan M.

    2013-01-01

    Spatial variation in food resources strongly influences many aspects of aquatic consumer ecology. Although large-scale controls over spatial variation in many aspects of food resources are well known, others have received little study. Here we investigated variation in the fatty acid (FA) composition of seston and primary consumers within (i.e., among habitats) and among tributary systems of Lake Michigan, USA. FA composition of food is important because all metazoans require certain FAs for proper growth and development that cannot be produced de novo, including many polyunsaturated fatty acids (PUFAs). Here we sampled three habitat types (river, rivermouth and nearshore zone) in 11 tributaries of Lake Michigan to assess the amount of FA in seston and primary consumers of seston. We hypothesize that among-system and among-habitat variation in FAs at the base of food webs would be related to algal production, which in turn is influenced by three land cover characteristics: 1) combined agriculture and urban lands (an indication of anthropogenic nutrient inputs that fuel algal production), 2) the proportion of surface waters (an indication of water residence times that allow algal producers to accumulate) and 3) the extent of riparian forested buffers (an indication of stream shading that reduces algal production). Of these three land cover characteristics, only intense land use appeared to strongly related to seston and consumer FA and this effect was only strong in rivermouth and nearshore lake sites. River seston and consumer FA composition was highly variable, but that variation does not appear to be driven by the watershed land cover characteristics investigated here. Whether the spatial variation in FA content at the base of these food webs significantly influences the production of economically important species higher in the food web should be a focus of future research.

  8. Reciprocal diversification in a complex plant-herbivore-parasitoid food web

    Directory of Open Access Journals (Sweden)

    Bokma Folmer

    2007-11-01

    Full Text Available Abstract Background Plants, plant-feeding insects, and insect parasitoids form some of the most complex and species-rich food webs. According to the classic escape-and-radiate (EAR hypothesis, these hyperdiverse communities result from coevolutionary arms races consisting of successive cycles of enemy escape, radiation, and colonization by new enemy lineages. It has also been suggested that "enemy-free space" provided by novel host plants could promote host shifts by herbivores, and that parasitoids could similarly drive diversification of gall form in insects that induce galls on plants. Because these central coevolutionary hypotheses have never been tested in a phylogenetic framework, we combined phylogenetic information on willow-galling sawflies with data on their host plants, gall types, and enemy communities. Results We found that evolutionary shifts in host plant use and habitat have led to dramatic prunings of parasitoid communities, and that changes in gall phenotype can provide "enemy-free morphospace" for millions of years even in the absence of host plant shifts. Some parasites have nevertheless managed to colonize recently-evolved gall types, and this has apparently led to adaptive speciation in several enemy groups. However, having fewer enemies does not in itself increase speciation probabilities in individual sawfly lineages, partly because the high diversity of the enemy community facilitates compensatory attack by remaining parasite taxa. Conclusion Taken together, our results indicate that niche-dependent parasitism is a major force promoting ecological divergence in herbivorous insects, and that prey divergence can cause speciation in parasite lineages. However, the results also show that the EAR hypothesis is too simplistic for species-rich food webs: instead, diversification seems to be spurred by a continuous stepwise process, in which ecological and phenotypic shifts in prey lineages are followed by a lagged evolutionary

  9. Evidence for the assimilation of ancient glacier organic carbon in a proglacial stream food web

    Science.gov (United States)

    Fellman, Jason; Hood, Eran; Raymond, Peter A.; Hudson, J.H.; Bozeman, Maura; Arimitsu, Mayumi L.

    2015-01-01

    We used natural abundance δ13C, δ15N, and Δ14C to compare trophic linkages between potential carbon sources (leaf litter, epilithic biofilm, and particulate organic matter) and consumers (aquatic macroinvertebrates and fish) in a nonglacial stream and two reaches of the heavily glaciated Herbert River. We tested the hypothesis that proglacial stream food webs are sustained by organic carbon released from glacial ecosystems. Carbon sources and consumers in the nonglacial stream had carbon isotope values that ranged from -30‰ to -25‰ for δ13C and from -14‰ to 53‰ for Δ14C reflecting a food web sustained mainly on contemporary primary production. In contrast, biofilm in the two glacial stream sites was highly Δ14C-depleted (-215‰ to 175‰) relative to the nonglacial stream consistent with the assimilation of ancient glacier organic carbon. IsoSource modeling showed that in upper Herbert River, macroinvertebrates (Δ14C = -171‰ to 22‰) and juvenile salmonids (Δ14C = −102‰ to 17‰) reflected a feeding history of both biofilm (~ 56%) and leaf litter (~ 40%). We estimate that in upper Herbert River on average 36% of the carbon incorporated into consumer biomass is derived from the glacier ecosystem. Thus, 14C-depleted glacial organic carbon was likely transferred to higher trophic levels through a feeding history of bacterial uptake of dissolved organic carbon and subsequent consumption of 14C-depleted biofilm by invertebrates and ultimately fish. Our findings show that the metazoan food web is sustained in part by glacial organic carbon such that future changes in glacial runoff could influence the stability and trophic structure of proglacial aquatic ecosystems.

  10. Stable Isotope Food Web Analysis of a Large Subtropical Lake: Alternative Explanations for 15N Enrichment of Pelagic vs. Littoral Fisheries

    Directory of Open Access Journals (Sweden)

    Karl E. Havens

    2003-01-01

    Full Text Available The food webs of littoral, pelagic, and littoral-pelagic ecotone (interface regions of a large subtropical lake were investigated using stable isotope ratio methods, expanding the focus of a previous fish-only study to include other food web components such as primary producers and invertebrates. In these food webs, δ13C increased ~4o/oo and δ15N increased ~10o/oo from primary producers to fish. The δ15N of fish was ~9o/oo in the littoral zone, ~10 o/oo in the ecotone, and ~12o/oo in the pelagic zone. The cross-habitat enrichment in fish 15N corresponded with both an increase in the size of fish and an increase in the δ15N of primary consumers (mollusks. Despite larger body size in the pelagic zone, fish in all three habitats appear to occur at the same average trophic level (TL = 4, assuming an enrichment factor of 3.4o/oo per trophic level, and normalizing to the δ15N of primary consumers.

  11. Food-web studies in shallow eutrophic lakes by the Netherlands Institute of Ecology: Main results, knowledge gaps and new perspectives

    NARCIS (Netherlands)

    Vijverberg, J.; Gulati, R.D.; Mooij, W.M.

    1993-01-01

    For more than 20 years scientists of the ‘Food-chain studies’ Group of the former Limnological Institute have been studying interactions within the pelagic food web. Purpose of research was to explain the structure and dynamics of the zooplankton and fish communities in lakes and reservoirs in

  12. Human Impacts and Climate Change Influence Nestedness and Modularity in Food-Web and Mutualistic Networks.

    Directory of Open Access Journals (Sweden)

    Kazuhiro Takemoto

    Full Text Available Theoretical studies have indicated that nestedness and modularity-non-random structural patterns of ecological networks-influence the stability of ecosystems against perturbations; as such, climate change and human activity, as well as other sources of environmental perturbations, affect the nestedness and modularity of ecological networks. However, the effects of climate change and human activities on ecological networks are poorly understood. Here, we used a spatial analysis approach to examine the effects of climate change and human activities on the structural patterns of food webs and mutualistic networks, and found that ecological network structure is globally affected by climate change and human impacts, in addition to current climate. In pollination networks, for instance, nestedness increased and modularity decreased in response to increased human impacts. Modularity in seed-dispersal networks decreased with temperature change (i.e., warming, whereas food web nestedness increased and modularity declined in response to global warming. Although our findings are preliminary owing to data-analysis limitations, they enhance our understanding of the effects of environmental change on ecological communities.

  13. Human Impacts and Climate Change Influence Nestedness and Modularity in Food-Web and Mutualistic Networks.

    Science.gov (United States)

    Takemoto, Kazuhiro; Kajihara, Kosuke

    2016-01-01

    Theoretical studies have indicated that nestedness and modularity-non-random structural patterns of ecological networks-influence the stability of ecosystems against perturbations; as such, climate change and human activity, as well as other sources of environmental perturbations, affect the nestedness and modularity of ecological networks. However, the effects of climate change and human activities on ecological networks are poorly understood. Here, we used a spatial analysis approach to examine the effects of climate change and human activities on the structural patterns of food webs and mutualistic networks, and found that ecological network structure is globally affected by climate change and human impacts, in addition to current climate. In pollination networks, for instance, nestedness increased and modularity decreased in response to increased human impacts. Modularity in seed-dispersal networks decreased with temperature change (i.e., warming), whereas food web nestedness increased and modularity declined in response to global warming. Although our findings are preliminary owing to data-analysis limitations, they enhance our understanding of the effects of environmental change on ecological communities.

  14. A freshwater food web model for the combined effects of nutrients and insecticide stress and subsequent recovery

    NARCIS (Netherlands)

    Traas, T.P.; Janse, J.H.; Brink, van den P.J.; Brock, T.C.M.; Aldenberg, T.

    2004-01-01

    A microcosm experiment that addressed the interaction between eutrophication processes and contaminants was analyzed using a food web model. Both direct and indirect effects of nutrient additions and a single insecticide application (chlorpyrifos) on biomass dynamics and recovery of functional

  15. Ecosystem ecology meets adaptive management: food web response to a controlled flood on the Colorado River, Glen Canyon

    Science.gov (United States)

    Cross, Wyatt F.; Baxter, Colden V.; Donner, Kevin C.; Rosi-Marshall, Emma J.; Kennedy, Theodore A.; Hall, Robert O.; Wellard Kelly, Holly A.; Rogers, R. Scott

    2011-01-01

    Large dams have been constructed on rivers to meet human demands for water, electricity, navigation, and recreation. As a consequence, flow and temperature regimes have been altered, strongly affecting river food webs and ecosystem processes. Experimental high-flow dam releases, i.e., controlled floods, have been implemented on the Colorado River, USA, in an effort to reestablish pulsed flood events, redistribute sediments, improve conditions for native fishes, and increase understanding of how dam operations affect physical and biological processes. We quantified secondary production and organic matter flows in the food web below Glen Canyon dam for two years prior and one year after an experimental controlled flood in March 2008. Invertebrate biomass and secondary production declined significantly following the flood (total biomass, 55% decline; total production, 56% decline), with most of the decline driven by reductions in two nonnative invertebrate taxa, Potamopyrgus antipodarum and Gammarus lacustris. Diatoms dominated the trophic basis of invertebrate production before and after the controlled flood, and the largest organic matter flows were from diatoms to the three most productive invertebrate taxa (P. antipodarum, G. lacustris, and Tubificida). In contrast to invertebrates, production of rainbow trout (Oncorhynchus mykiss) increased substantially (194%) following the flood, despite the large decline in total secondary production of the invertebrate assemblage. This counterintuitive result is reconciled by a post-flood increase in production and drift concentrations of select invertebrate prey (i.e., Chironomidae and Simuliidae) that supported a large proportion of trout production but had relatively low secondary production. In addition, interaction strengths, measured as species impact values, were strongest between rainbow trout and these two taxa before and after the flood, demonstrating that the dominant consumer—resource interactions were not

  16. Food-web inferences of stable isotope spatial patterns in copepods and yellowfin tuna in the pelagic eastern Pacific Ocean

    Science.gov (United States)

    Olson, Robert J.; Popp, Brian N.; Graham, Brittany S.; López-Ibarra, Gladis A.; Galván-Magaña, Felipe; Lennert-Cody, Cleridy E.; Bocanegra-Castillo, Noemi; Wallsgrove, Natalie J.; Gier, Elizabeth; Alatorre-Ramírez, Vanessa; Ballance, Lisa T.; Fry, Brian

    2010-07-01

    Evaluating the impacts of climate and fishing on oceanic ecosystems requires an improved understanding of the trophodynamics of pelagic food webs. Our approach was to examine broad-scale spatial relationships among the stable N isotope values of copepods and yellowfin tuna ( Thunnus albacares), and to quantify yellowfin tuna trophic status in the food web based on stable-isotope and stomach-contents analyses. Using a generalized additive model fitted to abundance-weighted-average δ 15N values of several omnivorous copepod species, we examined isotopic spatial relationships among yellowfin tuna and copepods. We found a broad-scale, uniform gradient in δ 15N values of copepods increasing from south to north in a region encompassing the eastern Pacific warm pool and parts of several current systems. Over the same region, a similar trend was observed for the δ 15N values in the white muscle of yellowfin tuna caught by the purse-seine fishery, implying limited movement behavior. Assuming the omnivorous copepods represent a proxy for the δ 15N values at the base of the food web, the isotopic difference between these two taxa, “ ΔYFT-COP,” was interpreted as a trophic-position offset. Yellowfin tuna trophic-position estimates based on their bulk δ 15N values were not significantly different than independent estimates based on stomach contents, but are sensitive to errors in the trophic enrichment factor and the trophic position of copepods. An apparent inshore-offshore, east to west gradient in yellowfin tuna trophic position was corroborated using compound-specific isotope analysis of amino acids conducted on a subset of samples. The gradient was not explained by the distribution of yellowfin tuna of different sizes, by seasonal variability at the base of the food web, or by known ambit distances (i.e. movements). Yellowfin tuna stomach contents did not show a regular inshore-offshore gradient in trophic position during 2003-2005, but the trophic

  17. Modeling 137Cs bioaccumulation in the salmon–resident killer whale food web of the Northeastern Pacific following the Fukushima Nuclear Accident

    International Nuclear Information System (INIS)

    Alava, Juan José; Gobas, Frank A.P.C.

    2016-01-01

    To track the long term bioaccumulation of 137 Cs in marine organisms off the Pacific Northwest coast of Canada, we developed a time dependent bioaccumulation model for 137 Cs in a marine mammalian food web that included fish-eating resident killer whales. The model outcomes show that 137 Cs can be expected to gradually bioaccumulate in the food web over time as demonstrated by the increase of the apparent trophic magnification factor of 137 Cs, ranging from 0.76 after 1 month of exposure to 2.0 following 30 years of exposure. 137 Cs bioaccumulation is driven by relatively rapid dietary uptake rates, moderate depuration rates in lower trophic level organisms and slow elimination rates in high trophic level organisms. Model estimates of the 137 Cs activity in species of the food web, based on current measurements and forecasts of 137 Cs activities in oceanic waters and sediments off the Canadian Pacific Northwest, indicate that the long term 137 Cs activities in fish species including Pacific herring, wild Pacific salmon, sablefish and halibut will remain well below the current 137 Cs-Canada Action Level for consumption (1000 Bq/kg) following a nuclear emergency. Killer whales and Pacific salmon are expected to exhibit the largest long term 137 Cs activities and may be good sentinels for monitoring 137 Cs in the region. Assessment of the long term consequences of 137 Cs releases from the Fukushima aftermath should consider the extent of ecological magnification in addition to ocean dilution. - Highlights: • A food web bioaccumulation model to assess the biomagnification of 137 Cs is developed. • Cesium 137 exhibits bioaccumulation over time as simulated by the model. • Predicted activities in marine biota are below 137 Cs-food consumption benchmarks. • Long-term monitoring of 137 Cs in the ocean will improve the model predictions.

  18. Changes in patterns of persistent halogenated compounds through a pelagic food web in the Baltic Sea

    DEFF Research Database (Denmark)

    Stephansen, Diana Agnete; Svendsen, Tore Christian; Vorkamp, Katrin

    2012-01-01

    The concentrations and patterns of persistent halogenated compounds (PHCs), including polychlorinated biphenyls (PCBs), DDT, hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB) and polybrominated diphenyl ethers (PBDEs) were examined in a pelagic food web from the southern Baltic Sea consisting...... for the assessment of PHC patterns, e.g. for tracing migratory fish....

  19. Pendeteksian Malware pada Lingkungan Aplikasi Web dengan Kategorisasi Dokumen

    Directory of Open Access Journals (Sweden)

    Fransiskus Gusti Ngurah Dwika Setiawan

    2017-03-01

    Full Text Available Jumlah aplikasi berbasis web semakin bertambah seiring dengan perkembangan teknologi informasi. Dengan bertambahnya jumlah aplikasi web, serangan-serangan yang dilakukan terhadap aplikasi-aplikasi web tersebut juga meningkat. Salah satu jenis serangan yang marak dilakukan terhadap aplikasi web adalah penyisipan malware seperti web shell yang dapat memberikan akses bebas terhadap komputer server kepada penyerang.Dalam makalah ini, dijelaskan implementasi aplikasi yang menerapkan teknik kategorisasi dokumen untuk mendeteksi malware atau kode malicious khususnya jenis web shell dengan teknik kategorisasi dokumen. Proses kategorisasi dokumen meliputi praproses dan tokenisasi kode sumber, pembuatan model classifier Multinomial Naive Bayes dan Decision Tree, dan klasifikasi dokumen menggunakan classifier yang telah dibuat. Uji coba yang dilakukan terhadap 718 file kode sumber PHP menghasilkan tingkat precision dari 72% hingga 83% dan recall 83% hingga 97%.

  20. Analysis and prediction of pest dynamics in an agroforestry context using Tiko'n, a generic tool to develop food web models

    Science.gov (United States)

    Rojas, Marcela; Malard, Julien; Adamowski, Jan; Carrera, Jaime Luis; Maas, Raúl

    2017-04-01

    While it is known that climate change will impact future plant-pest population dynamics, potentially affecting crop damage, agroforestry with its enhanced biodiversity is said to reduce the outbreaks of pest insects by providing natural enemies for the control of pest populations. This premise is known in the literature as the natural enemy hypothesis and has been widely studied qualitatively. However, disagreement still exists on whether biodiversity enhancement reduces pest outbreaks, showing the need of quantitatively understanding the mechanisms behind the interactions between pests and natural enemies, also known as trophic interactions. Crop pest models that study insect population dynamics in agroforestry contexts are very rare, and pest models that take trophic interactions into account are even rarer. This may be due to the difficulty of representing complex food webs in a quantifiable model. There is therefore a need for validated food web models that allow users to predict the response of these webs to changes in climate in agroforestry systems. In this study we present Tiko'n, a Python-based software whose API allows users to rapidly build and validate trophic web models; the program uses a Bayesian inference approach to calibrate the models according to field data, allowing for the reuse of literature data from various sources and reducing the need for extensive field data collection. Tiko'n was run using coffee leaf miner (Leucoptera coffeella) and associated parasitoid data from a shaded coffee plantation, showing the mechanisms of insect population dynamics within a tri-trophic food web in an agroforestry system.

  1. Interaction between birds and macrofauna within food webs of six intertidal habitats of the Wadden Sea.

    Science.gov (United States)

    Horn, Sabine; de la Vega, Camille; Asmus, Ragnhild; Schwemmer, Philipp; Enners, Leonie; Garthe, Stefan; Binder, Kirsten; Asmus, Harald

    2017-01-01

    The determination of food web structures using Ecological Network Analysis (ENA) is a helpful tool to get insight into complex ecosystem processes. The intertidal area of the Wadden Sea is structured into diverse habitat types which differ in their ecological functioning. In the present study, six different intertidal habitats (i.e. cockle field, razor clam field, mud flat, mussel bank, sand flat and seagrass meadow) were analyzed using ENA to determine similarities and characteristic differences in the food web structure of the systems. All six systems were well balanced between their degree of organization and their robustness. However, they differed in their detailed features. The cockle field and the mussel bank exhibited a strong dependency on external imports. The razor clam field appeared to be a rather small system with low energy transfer. In the mud flat microphytobenthos was used as a main food source and the system appeared to be sensitive to perturbations. Bird predation was the most pronounced in the sand flat and the seagrass meadow and led to an increase in energy transfer and parallel trophic cycles in these habitats. Habitat diversity appears to be an important trait for the Wadden Sea as each subsystem seems to have a specific role in the overall functioning of the entire ecosystem.

  2. Adult recall of tobacco advertising on the Internet.

    Science.gov (United States)

    Hrywna, Mary; Delnevo, Cristine D; Lewis, M Jane

    2007-11-01

    This study examined the prevalence and characteristics of New Jersey adults who reported seeing tobacco products advertised on the Internet and described the means by which these products were advertised. Data were analyzed from the New Jersey Adult Tobacco Survey (NJATS), a repeated, cross-sectional, random-digit-dial telephone survey conducted with a statewide representative sample. We used logistic regression to determine factors associated with recall of tobacco Internet advertising, adjusting for demographics, smoking behavior variables, and receipt of tobacco industry direct mail. Participants included 3,930 adults who completed the 2001 NJATS, 4,004 adults who completed the 2002 survey, and 3,062 adults who completed the 2005 survey. The proportion of adult Internet users reporting exposure to tobacco product advertising on the Internet has increased each year (6.9% in 2001, 15.6% in 2002, 17.8% in 2005). Based on 2005 data, recall of tobacco product advertising on the Internet was higher among males young adults aged 18-24 years, Asians, adults who reported receipt of direct mail advertising, and adults with a postcollege education. In addition, adult Internet users most often reported seeing tobacco products advertised on the Internet via pop-up or banner ads (60.7%), followed by E-mail messages (24.6%), and Web sites (14.9%). Recall of tobacco advertising by Internet users increased between 2001 and 2005 and was particularly high among certain subgroups. An urgent need exists for expanded surveillance of Internet tobacco sales and marketing practices.

  3. Response of the benthic food web to short- and long-term nutrient enrichment in saltmarsh mudflats

    NARCIS (Netherlands)

    Pascal, P.-Y.; Fleeger, J.W.; Boschker, H.T.S.; Mitwally, H.M.; Johnson, D.S.

    2013-01-01

    We examined the responses of biota at or near the base of the benthic food web to nutrient enrichment in salt marsh mudflats in Plum Island estuary (Massachusetts, USA). To simulate eutrophication, nitrate and phosphate loading rates were increased 10- to 15-fold in creeks fertilized for 2 mo (i.e.

  4. Methodological advances to study the diversity of soil protists and their functioning in soil food webs

    NARCIS (Netherlands)

    Geisen, Stefan; Bonkowski, Michael

    2018-01-01

    Abstract Soils host the most complex communities of organisms, which are still largely considered as an unknown ‘black box’. A key role in soil food webs is held by the highly abundant and diverse group of protists. Traditionally, soil protists are considered as the main consumers of bacteria in

  5. Methodological advances to study the diversity of soil protists and their functioning in soil food webs

    NARCIS (Netherlands)

    Geisen, Stefan; Bonkowski, Michael

    2017-01-01

    Soils host the most complex communities of organisms, which are still largely considered as an unknown 'black box'. A key role in soil food webs is held by the highly abundant and diverse group of protists. Traditionally, soil protists are considered as the main consumers of bacteria in soils.

  6. A Web site-based reporting system for monitoring home treatment during oral immunotherapy for food allergy.

    Science.gov (United States)

    Nachshon, Liat; Goldberg, Michael R; Elizur, Arnon; Levy, Michael B; Schwartz, Naama; Katz, Yitzhak

    2015-06-01

    Reactions during the home treatment phase of oral immunotherapy (OIT) are not uncommon. An ongoing accurate reporting of home treatment outcomes is crucial for the safety and success of OIT. Previous reports have shown that as few as 20% of patients are truly compliant with paper-based diaries. To develop a Web site-based electronic reporting system (web-RS) for monitoring home treatment during OIT for food allergy. A web-RS was developed and incorporated a thorough questionnaire querying for pertinent data including the dose(s) consumed, occurrence and details of adverse reactions, treatment(s), and relevant potential exacerbating factors. All patients enrolled in milk, peanut, or egg OIT programs for at least 4 weeks from November 2012 through January 2014 were introduced to web-RS (n = 157). Successful reporting through web-RS was defined by consecutive reporting during the first home treatment phase (24 days) after its introduction. Comparisons were made with a previous group of OIT-treated patients (n = 100) who reported by E-mail. Successful reporting was achieved by 142 of 157 patients (90.44%) in contrast to a 75% success rate with E-mail (P = .0009). The odds for successful reporting using web-RS were 3.1 (95% confidence interval 1.6-6.3) times higher compared with using E-mail. Mild reactions were reported more frequently with web-RS (P = .0032). Patient reports were constantly available in real time for medical staff review. No complaints regarding web-RS feasibility were reported. One risk factor for failure to use web-RS was a patient's prior successful OIT experience without using web-RS (P = .012). A web-RS can be a powerful tool for improving OIT safety by achieving a high level of patient cooperation in reporting home treatment results. Copyright © 2015 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

  7. Free Recall Shows Similar Reactivation Behavior as Recognition & Cued Recall

    OpenAIRE

    Tarnow, Eugen

    2016-01-01

    I find that the total retrieval time in word free recall increases linearly with the total number of items recalled. Measured slopes, the time to retrieve an additional item, vary from 1.4-4.5 seconds per item depending upon presentation rate, subject age and whether there is a delay after list presentation or not. These times to retrieve an additional item obey a second linear relationship as a function of the recall probability averaged over the experiment, explicitly independent of subject...

  8. Contrasting response to nutrient manipulation in Arctic mesocosms are reproduced by a minimum microbial food web model.

    Science.gov (United States)

    Larsen, Aud; Egge, Jorun K; Nejstgaard, Jens C; Di Capua, Iole; Thyrhaug, Runar; Bratbak, Gunnar; Thingstad, T Frede

    2015-03-01

    A minimum mathematical model of the marine pelagic microbial food web has previously shown to be able to reproduce central aspects of observed system response to different bottom-up manipulations in a mesocosm experiment Microbial Ecosystem Dynamics (MEDEA) in Danish waters. In this study, we apply this model to two mesocosm experiments (Polar Aquatic Microbial Ecology (PAME)-I and PAME-II) conducted at the Arctic location Kongsfjorden, Svalbard. The different responses of the microbial community to similar nutrient manipulation in the three mesocosm experiments may be described as diatom-dominated (MEDEA), bacteria-dominated (PAME-I), and flagellated-dominated (PAME-II). When allowing ciliates to be able to feed on small diatoms, the model describing the diatom-dominated MEDEA experiment give a bacteria-dominated response as observed in PAME I in which the diatom community comprised almost exclusively small-sized cells. Introducing a high initial mesozooplankton stock as observed in PAME-II, the model gives a flagellate-dominated response in accordance with the observed response also of this experiment. The ability of the model originally developed for temperate waters to reproduce population dynamics in a 10°C colder Arctic fjord, does not support the existence of important shifts in population balances over this temperature range. Rather, it suggests a quite resilient microbial food web when adapted to in situ temperature. The sensitivity of the model response to its mesozooplankton component suggests, however, that the seasonal vertical migration of Arctic copepods may be a strong forcing factor on Arctic microbial food webs.

  9. Comparison of validity of food group intake by food frequency questionnaire between pre- and post- adjustment estimates derived from 2-day 24-hour recalls in combination with the probability of consumption.

    Science.gov (United States)

    Kim, Dong Woo; Oh, Se-Young; Kwon, Sung-Ok; Kim, Jeongseon

    2012-01-01

    Validation of a food frequency questionnaire (FFQ) utilising a short-term measurement method is challenging when the reference method does not accurately reflect the usual food intake. In addition, food group intake that is not consumed on daily basis is more critical when episodically consumed foods are related and compared. To overcome these challenges, several statistical approaches have been developed to determine usual food intake distributions. The Multiple Source Method (MSM) can calculate the usual food intake by combining the frequency questions of an FFQ with the short-term food intake amount data. In this study, we applied the MSM to estimate the usual food group intake and evaluate the validity of an FFQ with a group of 333 Korean children (aged 3-6 y) who completed two 24-hour recalls (24HR) and one FFQ in 2010. After adjusting the data using the MSM procedure, the true rate of non-consumption for all food groups was less than 1% except for the beans group. The median Spearman correlation coefficients against FFQ of the mean of 2-d 24HRs data and the MSM-adjusted data were 0.20 (range: 0.11 to 0.40) and 0.35 (range: 0.14 to 0.60), respectively. The weighted kappa values against FFQ ranged from 0.08 to 0.25 for the mean of 2-d 24HRs data and from 0.10 to 0.41 for the MSM-adjusted data. For most food groups, the MSM-adjusted data showed relatively stronger correlations against FFQ than raw 2-d 24HRs data, from 0.03 (beverages) to 0.34 (mushrooms). The results of this study indicated that the application of the MSM, which was a better estimate of the usual intake, could be worth considering in FFQ validation studies among Korean children.

  10. Potential impacts of ocean acidification on the Puget Sound food web from a model study (NCEI Accession 0134852)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This archival package contains output from a study designed to evaluate the impacts of ocean acidification on the food web of Puget Sound, a large estuary in the...

  11. Family meal traditions. Comparing reported childhood food habits to current food habits among university students.

    Science.gov (United States)

    De Backer, Charlotte J S

    2013-10-01

    The aim of this study is to investigate if reported childhood food habits predict the food habits of students at present. Questions addressed are: does the memory of childhood family meals promote commensality among students? Does the memory of (grand)parents' cooking influence students' cooking? And, is there still a gender difference in passing on everyday cooking skills? Using a cross-sectional survey, 104 students were asked about their current eating and cooking habits, and their eating habits and the cooking behavior of their (grand)parents during their childhood. Results show that frequencies in reported childhood family meals predict frequencies of students' commensality at present. The effects appear for breakfast and dinner, and stay within the same meal: recalled childhood family breakfasts predict current breakfast commensality, recalled childhood family dinners predict current dinner commensality. In terms of recalled cookery of (grand)parents and the use of family recipes a matrilineal dominance can be observed. Mothers are most influential, and maternal grandmothers outscore paternal grandmothers. Yet, fathers' childhood cooking did not pass unnoticed either. They seem to influence male students' cookery. Overall, in a life-stage of transgression students appear to maintain recalled childhood food rituals. Suggestions are discussed to further validate these results. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Distribution of polycyclic aromatic hydrocarbons in the food web of a high mountain lake, Pyrenees, Catalonia, Spain.

    Science.gov (United States)

    Vives, Ingrid; Grimalt, Joan O; Ventura, Marc; Catalan, Jordi

    2005-06-01

    We investigated the contents of polycyclic aromatic hydrocarbons (PAHs) in the food web organisms included in the diet of brown trout from a remote mountain lake. The preferential habitat and trophic level of the component species have been assessed from the signature of stable isotopes (delta13C and delta15N). Subsequently, the patterns of accumulation and transformation of these hydrocarbons in the food chain have been elucidated. Most of the food web organisms exhibit PAH distributions largely dominated by phenanthrene, which agrees with its predominance in atmospheric deposition, water, and suspended particles. Total PAH levels are higher in the organisms from the littoral habitat than from the deep sediments or the pelagic water column. However, organisms from deep sediments exhibit higher proportions of higher molecular weight PAH than those in other lake areas. Distinct organisms exhibit specific features in their relative PAH composition that point to different capacities for uptake and metabolic degradation. Brown trout show an elevated capacity for metabolic degradation because they have lower PAH concentrations than food and they are enriched strongly in lower molecular weight compounds. The PAH levels in trout highly depend on organisms living in the littoral areas. Fish exposure to PAH, therefore, may vary from lake to lake according to the relative contribution of littoral organisms to their diet.

  13. Effects of whaling on the structure of the Southern Ocean food web: insights on the "krill surplus" from ecosystem modelling.

    Directory of Open Access Journals (Sweden)

    Szymon Surma

    Full Text Available The aim of this study was to examine the ecological plausibility of the "krill surplus" hypothesis and the effects of whaling on the Southern Ocean food web using mass-balance ecosystem modelling. The depletion trajectory and unexploited biomass of each rorqual population in the Antarctic was reconstructed using yearly catch records and a set of species-specific surplus production models. The resulting estimates of the unexploited biomass of Antarctic rorquals were used to construct an Ecopath model of the Southern Ocean food web existing in 1900. The rorqual depletion trajectory was then used in an Ecosim scenario to drive rorqual biomasses and examine the "krill surplus" phenomenon and whaling effects on the food web in the years 1900-2008. An additional suite of Ecosim scenarios reflecting several hypothetical trends in Southern Ocean primary productivity were employed to examine the effect of bottom-up forcing on the documented krill biomass trend. The output of the Ecosim scenarios indicated that while the "krill surplus" hypothesis is a plausible explanation of the biomass trends observed in some penguin and pinniped species in the mid-20th century, the excess krill biomass was most likely eliminated by a rapid decline in primary productivity in the years 1975-1995. Our findings suggest that changes in physical conditions in the Southern Ocean during this time period could have eliminated the ecological effects of rorqual depletion, although the mechanism responsible is currently unknown. Furthermore, a decline in iron bioavailability due to rorqual depletion may have contributed to the rapid decline in overall Southern Ocean productivity during the last quarter of the 20th century. The results of this study underscore the need for further research on historical changes in the roles of top-down and bottom-up forcing in structuring the Southern Ocean food web.

  14. Divergent composition but similar function of soil food webs of individual plants: plant species and community effects

    NARCIS (Netherlands)

    Bezemer, T.M.; Fountain, T.; Barea, J.M.; Christensen, S.; Dekker, S.C.; Duyts, H.; Hal, van R.; Harvey, J.A.; Hedlund, K.; Maraun, M.; Mikola, J.; Mladenov, A.G.; Robin, C.; Ruiter, de P.C.; Scheu, H.; Setälä, S.; šmilauer, P.; Putten, van der W.H.

    2010-01-01

    Soils are extremely rich in biodiversity, and soil organisms play pivotal roles in supporting terrestrial life, but the role that individual plants and plant communities play in influencing the diversity and functioning of soil food webs remains highly debated. Plants, as primary producers and

  15. Divergent composition but similar function of soil food webs beneath individual plants: plant species and community effects

    NARCIS (Netherlands)

    Bezemer, T.M.; Fountain, M.T.; Barea, J.M.; Christensen, S.; Dekker, S.C.; Duyts, H.; van Hal, R.; Harvey, J.A.; Hedlund, K.; Maraun, M.; Mikola, J.; Mladenov, A.G.; Robin, C.; de Ruiter, P.C.; Scheu, S.; Setälä, H.; Milauer, P.; Van der Putten, W.H.

    2010-01-01

    Soils are extremely rich in biodiversity, and soil organisms play pivotal roles in supporting terrestrial life, but the role that individual plants and plant communities play in influencing the diversity and functioning of soil food webs remains highly debated. Plants, as primary producers and

  16. Plant species identity and diversity effects on different trophic levels of nematodes in the soil food web

    NARCIS (Netherlands)

    De Deyn, G.B.; Raaijmakers, C.E.; Van Ruijven, J.; Berendse, F.; Van der Putten, W.H.

    2004-01-01

    Previous studies on biodiversity and soil food web composition have mentioned plant species identity, as well as plant species diversity as the main factors affecting the abundance and diversity of soil organisms. However, most studies have been carried out under limitations of time, space, or

  17. Bacterial traits, organism mass, and numerical abundance in the detrital soil food web of Dutch agricultural grasslands

    NARCIS (Netherlands)

    Mulder, C.; Cohen, J.E.; Setälä, H.; Bloem, J.; Breure, A.M.

    2005-01-01

    This paper compares responses to environmental stress of the ecophysiological traits of organisms in the detrital soil food webs of grasslands in the Netherlands, using the relationship between average body mass M and numerical abundance N. The microbial biomass and biodiversity of belowground fauna

  18. A finely tuned symphony of factors modulates the microbial food web of a freshwater reservoir in spring

    Czech Academy of Sciences Publication Activity Database

    Šimek, Karel; Nedoma, Jiří; Znachor, Petr; Kasalický, Vojtěch; Jezbera, Jan; Horňák, Karel; Seďa, Jaromír

    2014-01-01

    Roč. 59, č. 5 (2014), s. 1477-1492 ISSN 0024-3590 R&D Projects: GA ČR(CZ) GA13-00243S Institutional support: RVO:60077344 Keywords : microbial food web * freshwater reservoir * limnology Subject RIV: EE - Microbiology, Virology Impact factor: 3.794, year: 2014

  19. Chironomidae feeding habits in different habitats from a Neotropical floodplain: exploring patterns in aquatic food webs.

    Science.gov (United States)

    Butakka, C M M; Ragonha, F H; Train, S; Pinha, G D; Takeda, A M

    2016-02-01

    Ecological studies on food webs have considerably increased in recent decades, especially in aquatic communities. Because Chironomidae family are highly specious, occurring in almost all aquatic habitats is considered organisms-key to initiate studies on ecological relationships and trophic webs. We tested the hypothesis that the diversity of the morphospecies diet reflects differences on both the food items available among habitats and the preferences of larval feeding. We analyzed the gut content of the seven most abundant Chironomidae morphospecies of the different habitats from the Upper Paraná River. We categorized the food items found into algae, fungal spores, fragments of plants, algae and animal fragments and sponge spicules. We observed the algae predominance in the gut content of morphospecies from lakes. Considering the different regions from each lake, we registered the highest food abundance in the littoral regions in relation to the central regions. From the variety of feeding habits (number of item kinds), we classified Chironomus strenzkei, Tanytarsus sp.1, Procladius sp.1 as generalist morphospecies. We found a nested pattern between food items and Chironomidae morphospecies, where some items were common to all taxa (e.g., Bacillariophyceae algae, especially), while others were found in specific morphospecies (e.g., animals fragments found in Procladius sp.1). The algae represented the most percentage of gut contents of Chironomidae larvae. This was especially true for the individuals from littoral regions, which is probably due to the major densities of algae associated to macrophytes, which are abundant in these regions. Therefore, the feeding behavior of these morphospecies was generalist and not selective, depending only of the available resources.

  20. Dietary quality varies according to data collection instrument: a comparison between a food frequency questionnaire and 24-hour recall

    Directory of Open Access Journals (Sweden)

    Paulo Rogério Melo Rodrigues

    2016-01-01

    Full Text Available Abstract The objective of this study was to assess the agreement between the Brazilian Healthy Eating Index – Revised (BHEI-R, estimated by a food frequency questionnaire (FFQ and multiple 24-hour recalls (24h-R. The Wilcoxon paired test, partial correlations (PC, intraclass correlation coefficient (ICC, and Bland-Altman method were used. The total BHEI-R scores and its components (“total fruits”, “whole fruits”, “total vegetables”, “integral cereals”, “saturated fat”, “sodium”, and “energy intake derived from solid fat, added sugar, and alcoholic beverages” were statistically different, with the ICC and PC indicating poor concordance and correlation. The mean concordance estimated for the total BHEI-R and its components varied from 68% for “integral cereals” to 147% for “whole fruits”. The suitable concordance limits were violated for most of the components of the BHEI-R. Poor concordance was observed between the BHEI-R estimated by the FFQ and by multiple 24h-R, which indicated a strong reliability of the BHEI-R on the instrument used to collect information on food consumption.

  1. Comparison of self-reported dietary intakes from the Automated Self-Administered 24-h recall, 4-d food records, and food-frequency questionnaires against recovery biomarkers.

    Science.gov (United States)

    Park, Yikyung; Dodd, Kevin W; Kipnis, Victor; Thompson, Frances E; Potischman, Nancy; Schoeller, Dale A; Baer, David J; Midthune, Douglas; Troiano, Richard P; Bowles, Heather; Subar, Amy F

    2018-01-01

    A limited number of studies have evaluated self-reported dietary intakes against objective recovery biomarkers. The aim was to compare dietary intakes of multiple Automated Self-Administered 24-h recalls (ASA24s), 4-d food records (4DFRs), and food-frequency questionnaires (FFQs) against recovery biomarkers and to estimate the prevalence of under- and overreporting. Over 12 mo, 530 men and 545 women, aged 50-74 y, were asked to complete 6 ASA24s (2011 version), 2 unweighed 4DFRs, 2 FFQs, two 24-h urine collections (biomarkers for protein, potassium, and sodium intakes), and 1 administration of doubly labeled water (biomarker for energy intake). Absolute and density-based energy-adjusted nutrient intakes were calculated. The prevalence of under- and overreporting of self-report against biomarkers was estimated. Ninety-two percent of men and 87% of women completed ≥3 ASA24s (mean ASA24s completed: 5.4 and 5.1 for men and women, respectively). Absolute intakes of energy, protein, potassium, and sodium assessed by all self-reported instruments were systematically lower than those from recovery biomarkers, with underreporting greater for energy than for other nutrients. On average, compared with the energy biomarker, intake was underestimated by 15-17% on ASA24s, 18-21% on 4DFRs, and 29-34% on FFQs. Underreporting was more prevalent on FFQs than on ASA24s and 4DFRs and among obese individuals. Mean protein and sodium densities on ASA24s, 4DFRs, and FFQs were similar to biomarker values, but potassium density on FFQs was 26-40% higher, leading to a substantial increase in the prevalence of overreporting compared with absolute potassium intake. Although misreporting is present in all self-report dietary assessment tools, multiple ASA24s and a 4DFR provided the best estimates of absolute dietary intakes for these few nutrients and outperformed FFQs. Energy adjustment improved estimates from FFQs for protein and sodium but not for potassium. The ASA24, which now can be

  2. Illicit Internet availability of drugs subject to recall and patient safety consequences.

    Science.gov (United States)

    Mackey, Tim K; Aung, Phyo; Liang, Bryan A

    2015-12-01

    Permanently recalled drugs are a public health concern if they remain accessible in violation of applicable regulation. Illicit online pharmacies act as an alternative form of access and have been associated with the sale to patients of counterfeit/falsified/fraudulent/substandard drugs. We wished to determine if permanently recalled and significantly restricted drugs were illegally marketed for sale online. The study was conducted in two phases with two objectives. The first phase attempted to identify drugs subject to permanent recall in certain major pharmaceutical markets as well as those listed as recalled or significantly restricted by the United Nations. We also examined the market authorization status of identified drugs in China and India. The second phase used structured searches on the Internet to determine if identified drugs were marketed for sale online. The World Wide Web. After identification of permanently recalled and restricted drugs we conducted Internet searches for illegal "no prescription" marketing events. We assessed the form of marketing, whether a site offered direct-to-patient sale, use of social media marketing, and the site's compliance status with external monitoring bodies. Number of recalled drugs marketed as available for purchase on the Internet. We identified 16 class I equivalent permanently recalled or restricted drugs, 56.3 % (n = 9) of which maintained market authorization in either China or India. Half (n = 8) were marketed for sale online without a prescription direct-to-patient. Use of social media marketing was mixed, with only 18.8 % (n = 3) of recalled drugs having a presence on Facebook, though 50.0 % (n = 8) had content on Twitter. We also found the majority (68.8 %, n = 11) were available and marketed for sale by vendors on the wholesale/business-to-business website alibaba.com primarily as active pharmaceutical ingredient. Despite efforts in several countries to restrict access to these drugs or permanently remove

  3. Calibration of the brief food frequency questionnaire among patients on dialysis.

    Science.gov (United States)

    Delgado, Cynthia; Ward, Patricia; Chertow, Glenn M; Storer, Lindsey; Dalrymple, Lorien; Block, Torin; Kaysen, George A; Kornak, John; Grimes, Barbara; Kutner, Nancy G; Johansen, Kirsten L

    2014-05-01

    Estimating dietary intake is challenging in patients with chronic diseases. The aim of this study was to calibrate the Block Brief 2000 food frequency questionnaire (BFFQ) using 3-day food diary records among patients on dialysis. Data from 3-day food diary records from 146 patients new to dialysis were reviewed and entered into National Cancer Institute self-administered 24-hour dietary recall (ASA24), a web-based dietary interview system. The information was then re-entered omitting foods reported in the diaries that were not in the BFFQ to generate a "BFFQ-restricted" set of intakes. We modeled each major dietary component (i.e., energy [total calories], protein, carbohydrate, fat) separately using linear regression. The main independent variables were BFFQ-restricted food diary estimates computed as the average of the 3 days of diaries, restricted to items included in the BFFQ, with the unrestricted 3-day food diary averages as dependent variables. The BFFQ-restricted diary energy estimate of 1,325 ± 545 kcal was 87% of the energy intake in the full food diary (1,510.3 ± 510.4, P food diary (156.7 ± 78.7 g vs. 190.4 ± 72.7, P food diaries, but simple calibration equations can be used to approximate total intake from BFFQ responses. Published by Elsevier Inc.

  4. Cognitive Factors Affecting Free Recall, Cued Recall, and Recognition Tasks in Alzheimer’s Disease

    OpenAIRE

    Takashi Yamagishi; Takuya Sato; Atsushi Sato; Toru Imamura

    2012-01-01

    Background/Aims: Our aim was to identify cognitive factors affecting free recall, cued recall, and recognition tasks in patients with Alzheimer’s disease (AD). Subjects: We recruited 349 consecutive AD patients who attended a memory clinic. Methods: Each patient was assessed using the Alzheimer’s Disease Assessment Scale (ADAS) and the extended 3-word recall test. In this task, each patient was asked to freely recall 3 previously presented words. If patients could not recall 1 or more of the ...

  5. Estimation and evaluation of the radioactive contamination through a food web in an aquatic ecosystem, (2). System analysis of the transfer of radionuclides through a food web

    Energy Technology Data Exchange (ETDEWEB)

    Aoyama, Isao; Inoue, Yoriteru [Kyoto Univ. (Japan). Faculty of Engineering

    1975-06-01

    In order to estimate and evaluate the radioactivity concentration in an aquatic ecosystem, the transfer of radioactivity through a food web should be considered. In this paper, systems analysis on the above problem was performed and a quantity of radioactivity in organisms concentrated through their diet was presented. It was found from numerical evaluation that whether the transfer of radioactivity through a diet is significant or not depended on such ecological factors as ration rates, assimilation rates, uptake rates, and turnover rates. The degree of the importance of these parameters on the concentration process of radioactivity was quantitatively evaluated by the mathematical technique of sensitivity analysis.

  6. Free Recall Curves: Nothing but Rehearsing Some Items More or Recalling Them Sooner?

    Science.gov (United States)

    Brodie, Delbert A.; Prytulak, Lubomir S.

    1975-01-01

    The hypothesis that free recall curves reflecting effects of serial position, presentation time and delay of recall are attributable to subjects' pattern of rehearsal was explored. Experiments varied the patterns of rehearsal to examine the effects on recall. (CHK)

  7. Use of Biopolymers in Antimicrobial Food Packaging

    Science.gov (United States)

    Recent outbreaks of foodborne illness and food recalls continue to push for innovative ways to inhibit microbial growth in foods. As an additional hurdle to food processes, antimicrobial food packaging can play an important role in reducing the risk of pathogen contamination of processed foods. In...

  8. The protozooplankton-ichthyoplankton trophic link: an overlooked aspect of aquatic food webs.

    Science.gov (United States)

    Montagnes, David J S; Dower, John F; Figueiredo, Gisela M

    2010-01-01

    Since the introduction of the microbial loop concept, awareness of the role played by protozooplankton in marine food webs has grown. By consuming bacteria, and then being consumed by metazooplankton, protozoa form a trophic link that channels dissolved organic material into the "classic" marine food chain. Beyond enhancing energy transfer to higher trophic levels, protozoa play a key role in improving the food quality of metazooplankton. Here, we consider a third role played by protozoa, but one that has received comparatively little attention: that as prey items for ichthyoplankton. For >100 years it has been known that fish larvae consume protozoa. Despite this, fisheries scientists and biological oceanographers still largely ignore protozoa when assessing the foodweb dynamics that regulate the growth and survival of larval fish. We review evidence supporting the importance of the protozooplankton-ichthyoplankton link, including examples from the amateur aquarium trade, the commercial aquaculture industry, and contemporary studies of larval fish. We then consider why this potentially important link continues to receive very little attention. We conclude by offering suggestions for quantifying the importance of the protozooplankton-ichthyoplankton trophic link, using both existing methods and new technologies.

  9. Two Sides of the Same Coin? Analysis of the Web-Based Social Media with Regard to the Image of the Agri-Food Sector in Germany

    Directory of Open Access Journals (Sweden)

    Justus Boehm

    2010-10-01

    Full Text Available  Never before has food been as safe and secure as it is today, but simultaneously, society has become increasingly critical towards agricultural and food related issues. This two-sided development between society and agribusiness will be analyzed using Framing Theory. A quantitative semantic analysis was applied to evaluate the web-based social media in Germany. 50,931 web posts were collected covering 21 issues identified as relevant for the agri-food sector. The results show that all contentious issues are mainly framed in a two-sided way. The modern productivity-driven industry is judged as a negative development, trends returning to a more natural food production are seen as positive.

  10. Isotopic evidence for anthropogenic impacts on aquatic food web dynamics and mercury cycling in a subtropical wetland ecosystem in the US

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yang, E-mail: ywang@magnet.fsu.edu [Department of Earth, Ocean and Atmospheric Science, Florida State University and National High Magnetic Field Laboratory, Tallahassee, FL 32306–4100 (United States); Gu, Binhe [South Florida Water Management District, West Palm Beach, FL 33406 (United States); Lee, Ming-Kuo [Department of Geology and Geography, Auburn University, Auburn, AL 36839 (United States); Jiang, Shijun, E-mail: sjiang@jnu.edu.cn [Institute of Hydrobiology/Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, Jinan University, Guangzhou, Guangdong 510632 (China); Xu, Yingfeng [Department of Earth, Ocean and Atmospheric Science, Florida State University and National High Magnetic Field Laboratory, Tallahassee, FL 32306–4100 (United States)

    2014-07-01

    Quantifying and predicting the food web consequences of anthropogenic changes is difficult using traditional methods (based on gut content analysis) because natural food webs are variable and complex. Here, stable and radioactive carbon isotopes are used, in conjunction with nitrogen isotopes and mercury (Hg) concentration data, to document the effects of land-use change on food webs and Hg bioaccumulation in the Everglades – a subtropical wetland ecosystem in the US. Isotopic signatures of largemouth bass and sunfish in reference (relatively pristine) wetlands indicate reliance on the food supply of modern primary production within the wetland. In contrast, both fish in areas impacted by agricultural runoff had radiocarbon ages as old as 540 years B.P., and larger isotopic variability than counterparts in reference wetlands, reflecting differences in the food web between impacted and reference wetlands. Consistent with this difference, particulate and dissolved organic matter in impacted areas had old radiocarbon ages (> 600 years B.P.), indicating that old carbon derived from historic peat deposits in the Everglades Agricultural Area was passed along the food chain to consumers. Significant radiocarbon deficiencies in largemouth bass and sunfish, relative to mosquitofish, in impacted areas most likely indicate a reduced dependence on small fish. Furthermore, largemouth bass and sunfish from impacted areas had much lower Hg contents than those from reference wetlands. Taken together, these data suggest a shift toward lower trophic levels and a possible reduction in mercury methylation in impacted wetlands. Our study provides clear evidence that hydrological modification and land-use change in the Everglades have changed the system from one driven primarily by in-situ productivity to one that is partially dependent on allochthonous carbon input from peat soils in the agricultural area and altered the Hg biogeochemical cycle in the wetlands. The results have

  11. Isotopic evidence for anthropogenic impacts on aquatic food web dynamics and mercury cycling in a subtropical wetland ecosystem in the US

    International Nuclear Information System (INIS)

    Wang, Yang; Gu, Binhe; Lee, Ming-Kuo; Jiang, Shijun; Xu, Yingfeng

    2014-01-01

    Quantifying and predicting the food web consequences of anthropogenic changes is difficult using traditional methods (based on gut content analysis) because natural food webs are variable and complex. Here, stable and radioactive carbon isotopes are used, in conjunction with nitrogen isotopes and mercury (Hg) concentration data, to document the effects of land-use change on food webs and Hg bioaccumulation in the Everglades – a subtropical wetland ecosystem in the US. Isotopic signatures of largemouth bass and sunfish in reference (relatively pristine) wetlands indicate reliance on the food supply of modern primary production within the wetland. In contrast, both fish in areas impacted by agricultural runoff had radiocarbon ages as old as 540 years B.P., and larger isotopic variability than counterparts in reference wetlands, reflecting differences in the food web between impacted and reference wetlands. Consistent with this difference, particulate and dissolved organic matter in impacted areas had old radiocarbon ages (> 600 years B.P.), indicating that old carbon derived from historic peat deposits in the Everglades Agricultural Area was passed along the food chain to consumers. Significant radiocarbon deficiencies in largemouth bass and sunfish, relative to mosquitofish, in impacted areas most likely indicate a reduced dependence on small fish. Furthermore, largemouth bass and sunfish from impacted areas had much lower Hg contents than those from reference wetlands. Taken together, these data suggest a shift toward lower trophic levels and a possible reduction in mercury methylation in impacted wetlands. Our study provides clear evidence that hydrological modification and land-use change in the Everglades have changed the system from one driven primarily by in-situ productivity to one that is partially dependent on allochthonous carbon input from peat soils in the agricultural area and altered the Hg biogeochemical cycle in the wetlands. The results have

  12. Fast and Accurate Approaches for Large-Scale, Automated Mapping of Food Diaries on Food Composition Tables

    Directory of Open Access Journals (Sweden)

    Marc Lamarine

    2018-05-01

    Full Text Available Aim of Study: The use of weighed food diaries in nutritional studies provides a powerful method to quantify food and nutrient intakes. Yet, mapping these records onto food composition tables (FCTs is a challenging, time-consuming and error-prone process. Experts make this effort manually and no automation has been previously proposed. Our study aimed to assess automated approaches to map food items onto FCTs.Methods: We used food diaries (~170,000 records pertaining to 4,200 unique food items from the DiOGenes randomized clinical trial. We attempted to map these items onto six FCTs available from the EuroFIR resource. Two approaches were tested: the first was based solely on food name similarity (fuzzy matching. The second used a machine learning approach (C5.0 classifier combining both fuzzy matching and food energy. We tested mapping food items using their original names and also an English-translation. Top matching pairs were reviewed manually to derive performance metrics: precision (the percentage of correctly mapped items and recall (percentage of mapped items.Results: The simpler approach: fuzzy matching, provided very good performance. Under a relaxed threshold (score > 50%, this approach enabled to remap 99.49% of the items with a precision of 88.75%. With a slightly more stringent threshold (score > 63%, the precision could be significantly improved to 96.81% while keeping a recall rate > 95% (i.e., only 5% of the queried items would not be mapped. The machine learning approach did not lead to any improvements compared to the fuzzy matching. However, it could increase substantially the recall rate for food items without any clear equivalent in the FCTs (+7 and +20% when mapping items using their original or English-translated names. Our approaches have been implemented as R packages and are freely available from GitHub.Conclusion: This study is the first to provide automated approaches for large-scale food item mapping onto FCTs. We

  13. Estimating effects of tidal power projects and climate change on threatened and endangered marine species and their food web.

    Science.gov (United States)

    Busch, D Shallin; Greene, Correigh M; Good, Thomas P

    2013-12-01

    Marine hydrokinetic power projects will operate as marine environments change in response to increased atmospheric carbon dioxide concentrations. We considered how tidal power development and stressors resulting from climate change may affect Puget Sound species listed under the U.S. Endangered Species Act (ESA) and their food web. We used risk tables to assess the singular and combined effects of tidal power development and climate change. Tidal power development and climate change posed risks to ESA-listed species, and risk increased with incorporation of the effects of these stressors on predators and prey of ESA-listed species. In contrast, results of a model of strikes on ESA-listed species from turbine blades suggested that few ESA-listed species are likely to be killed by a commercial-scale tidal turbine array. We applied scenarios to a food web model of Puget Sound to explore the effects of tidal power and climate change on ESA-listed species using more quantitative analytical techniques. To simulate development of tidal power, we applied results of the blade strike model. To simulate environmental changes over the next 50 years, we applied scenarios of change in primary production, plankton community structure, dissolved oxygen, ocean acidification, and freshwater flooding events. No effects of tidal power development on ESA-listed species were detected from the food web model output, but the effects of climate change on them and other members of the food web were large. Our analyses exemplify how natural resource managers might assess environmental effects of marine technologies in ways that explicitly incorporate climate change and consider multiple ESA-listed species in the context of their ecological community. Estimación de los Efectos de Proyectos de Energía de las Mareas y el Cambio Climático sobre Especies Marinas Amenazadas y en Peligro y su Red Alimentaria. © 2013 Society for Conservation Biology No claim to original US government works.

  14. Effects of sea-ice extent and krill or salp dominance on the Antarctic food web

    Science.gov (United States)

    Loeb, V.; Siegel, V.; Holm-Hansen, O.; Hewitt, R.; Fraser, W.; Trivelpiece, W.; Trivelpiece, S.

    1997-06-01

    Krill (Euphausia superba) provide a direct link between primary producers and higher trophic levels in the Antarctic marine food web. The pelagic tunicate Salpa thompsoni can also be important during spring and summer through the formation of extensive and dense blooms. Although salps are not a major dietary item for Antarctic vertebrate predators,, their blooms can affect adult krill reproduction and survival of krill larvae. Here we provide data from 1995 and 1996 that support hypothesized relationships between krill, salps and region-wide sea-ice conditions,. We have assessed salp consumption as a proportion of net primary production, and found correlations between herbivore densities and integrated chlorophyll-a that indicate that there is a degree of competition between krill and salps. Our analysis of the relationship between annual sea-ice cover and a longer time series of air temperature measurements, indicates a decreased frequency of winters with extensive sea-ice development over the last five decades. Our data suggest that decreased krill availability may affect the levels of their vertebrate predators. Regional warming and reduced krill abundance therefore affect the marine food web and krill resource management.

  15. Effects of zebra mussels on food webs: Interactions with juvenile bluegill and water residence time

    Science.gov (United States)

    Richardson, W.B.; Bartsch, L.A.

    1997-01-01

    We evaluated how water residence time mediated the impact of zebra mussels Dreissena polymorpha and bluegill sunfish Lepomis macrochirus on experimental food webs established in 1100-1 outdoor mesocosms. Water residence time was manipulated as a surrogate for seston resupply - a critical variable affecting growth and survival of suspension-feeding invertebrates. We used a 2 x 2 x 2 factorial experimental design with eight treatment combinations (3 replicates/treatment) including the presence or absence of Dreissena (2000 per m2), juvenile bluegill (40 per mesocosm), and short (1100 1 per d) or long (220 1 per d) water residence time. Measures of seston concentration (chlorophyll a, turbidity and suspended solids) were greater in the short- compared to long water-residence mesocosms, but intermediate in short water-residence mesocosms containing Dreissena. Abundance of rotifers (Keratella and Polyarthra) was reduced in Dreissena mesocosms and elevated in short residence time mesocosms. Cladocera abundance, in general, was unaffected by the presence of Dreissena; densities were higher in short-residence time mesocosms, and reduced in the presence of Lepomis. The growth of juvenile Lepomis were unaffected by Dreissena because of abundant benthic food. The final total mass of Dreissena was significantly greater in short- than long-residence mesocosms. Impacts of Dreissena on planktonic food webs may not only depend on the density of zebra mussels but also on the residence time of the surrounding water and the resupply of seston. ?? 1997 Kluwer Academic Publishers.

  16. Food microbe tracker: a web-based tool for storage and comparison of food-associated microbes.

    Science.gov (United States)

    Vangay, Pajau; Fugett, Eric B; Sun, Qi; Wiedmann, Martin

    2013-02-01

    Large amounts of molecular subtyping information are generated by the private sector, academia, and government agencies. However, use of subtype data is limited by a lack of effective data storage and sharing mechanisms that allow comparison of subtype data from multiple sources. Currently available subtype databases are generally limited in scope to a few data types (e.g., MLST. net) or are not publicly available (e.g., PulseNet). We describe the development and initial implementation of Food Microbe Tracker, a public Web-based database that allows archiving and exchange of a variety of molecular subtype data that can be cross-referenced with isolate source data, genetic data, and phenotypic characteristics. Data can be queried with a variety of search criteria, including DNA sequences and banding pattern data (e.g., ribotype or pulsed-field gel electrophoresis type). Food Microbe Tracker allows the deposition of data on any bacterial genus and species, bacteriophages, and other viruses. The bacterial genera and species that currently have the most entries in this database are Listeria monocytogenes, Salmonella, Streptococcus spp., Pseudomonas spp., Bacillus spp., and Paenibacillus spp., with over 40,000 isolates. The combination of pathogen and spoilage microorganism data in the database will facilitate source tracking and outbreak detection, improve discovery of emerging subtypes, and increase our understanding of transmission and ecology of these microbes. Continued addition of subtyping, genetic or phenotypic data for a variety of microbial species will broaden the database and facilitate large-scale studies on the diversity of food-associated microbes.

  17. Comparative analysis of food webs based on flow networks: effects of nutrient supply on structure and function of coastal plankton communities

    Science.gov (United States)

    Olsen, Yngvar; Reinertsen, Helge; Vadstein, Olav; Andersen, Tom; Gismervik, Ingrid; Duarte, Carlos; Agusti, Susana; Stibor, Herwig; Sommer, Ulrich; Lignell, Risto; Tamminen, Timo; Lancelot, Christiane; Rousseau, Veronique; Hoell, Espen; Sanderud, Knut Arvid

    2001-12-01

    The objective of COMWEB was to develop efficient analytical, numerical and experimental methods for assessing and predicting the effects of nutrient (N, P, Si) supply on the stability and persistence of pelagic food web structure and function in coastal waters. The experimental comparative work included a geographic gradient covering Baltic, Mediterranean, and NE Atlantic waters and a NE Atlantic gradient in state of eutrophication. COMWEB has been an experimental approach to coastal eutrophication, studying effects of enhanced nutrient supply on components and flows of the entire lower pelagic food web. Flow network representations of pelagic food webs has been a framework of data reduction and flows were established by sophisticated inverse modelling. Fundamental information on physiological properties of functional key species in the pelagic food web was used to constrain flow estimations. A main conclusion derived from the flow networks was that very little energy and materials were transferred from the microbial food web to the main food chain. The lower food web could therefore be described as two parallel food chains with relatively limited interaction between heterotrophic groups. Short-term effects of nutrient perturbations were examined in mesocosms along the geographic gradient. The response was comparable in all systems, with a stronger effect on the activity and biomass of autotrophic groups than those of heterotrophic ones. Mediterranean waters showed much lower autotrophic biomass response than Baltic and NE Atlantic waters, which responded almost equally. The response of primary production was, however, more comparable. High phytoplankton lysis rate explained this low accumulation of biomass in Mediterranean waters. The study of Atlantic coastal waters of different eutrophic states revealed that the ecological response was higher in the closed nutrient perturbed mesocosms than in open systems exposed for >4 summer months (summer/autumn season). The

  18. Comparison of diet measures from a food-frequency questionnaire with measures from repeated 24-hour dietary recalls. The Norwegian Women and Cancer Study.

    Science.gov (United States)

    Hjartåker, Anette; Andersen, Lene Frost; Lund, Eiliv

    2007-10-01

    To compare diet measures from a food-frequency questionnaire (FFQ) with measures from 24-hour dietary recalls (24HDRs). The participants answered an FFQ after completing four, repeated 24HDRs during a year. Norway, nationwide. Of 500 women randomly selected from The Norwegian Women and Cancer Study (the Norwegian arm of the European Prospective Investigation into Cancer and Nutrition), 286 agreed to participate and 238 completed the study. On the group level, the FFQ overestimated absolute intake in seven and underestimated intake in six of 21 food groups. Intakes of energy, fat, added sugar and alcohol were lower in the FFQ than in the 24HDRs, whereas intake of fibre was higher. Spearman's rank correlation coefficient ranged from 0.13 (desserts) to 0.82 (coffee) for foods, and from 0.25 (beta-carotene) to 0.67 (alcohol) for nutrients. Three per cent of the observations on nutrient intake fell in the opposite quintile when classified according to the FFQ as compared with the 24HDR. The median calibration coefficient, calculated by regression of the 24HDR data on the FFQ data, was 0.57 for foods and 0.38 for nutrients. The FFQ's ability to rank subjects was good for foods eaten frequently and fairly good for macronutrients in terms of energy percentages. Weaker ranking abilities were seen for foods eaten infrequently and for some micronutrients. The results underline the necessity of performing measurement error corrections.

  19. Central Puget Sound Ecopath/Ecosim model outputs - Developing food web models for ecosystem-based management applications in Puget Sound

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This project is developing food web models for ecosystem-based management applications in Puget Sound. It is primarily being done by NMFS FTEs and contractors, in...

  20. Analysis and prediction of agricultural pest dynamics with Tiko'n, a generic tool to develop agroecological food web models

    Science.gov (United States)

    Malard, J. J.; Rojas, M.; Adamowski, J. F.; Anandaraja, N.; Tuy, H.; Melgar-Quiñonez, H.

    2016-12-01

    While several well-validated crop growth models are currently widely used, very few crop pest models of the same caliber have been developed or applied, and pest models that take trophic interactions into account are even rarer. This may be due to several factors, including 1) the difficulty of representing complex agroecological food webs in a quantifiable model, and 2) the general belief that pesticides effectively remove insect pests from immediate concern. However, pests currently claim a substantial amount of harvests every year (and account for additional control costs), and the impact of insects and of their trophic interactions on agricultural crops cannot be ignored, especially in the context of changing climates and increasing pressures on crops across the globe. Unfortunately, most integrated pest management frameworks rely on very simple models (if at all), and most examples of successful agroecological management remain more anecdotal than scientifically replicable. In light of this, there is a need for validated and robust agroecological food web models that allow users to predict the response of these webs to changes in management, crops or climate, both in order to predict future pest problems under a changing climate as well as to develop effective integrated management plans. Here we present Tiko'n, a Python-based software whose API allows users to rapidly build and validate trophic web agroecological models that predict pest dynamics in the field. The programme uses a Bayesian inference approach to calibrate the models according to field data, allowing for the reuse of literature data from various sources and reducing the need for extensive field data collection. We apply the model to the cononut black-headed caterpillar (Opisina arenosella) and associated parasitoid data from Sri Lanka, showing how the modeling framework can be used to rapidly develop, calibrate and validate models that elucidate how the internal structures of food webs

  1. Biological vs. physical mixing effects on benthic food web dynamics.

    Directory of Open Access Journals (Sweden)

    Ulrike Braeckman

    Full Text Available Biological particle mixing (bioturbation and solute transfer (bio-irrigation contribute extensively to ecosystem functioning in sediments where physical mixing is low. Macrobenthos transports oxygen and organic matter deeper into the sediment, thereby likely providing favourable niches to lower trophic levels (i.e., smaller benthic animals such as meiofauna and bacteria and thus stimulating mineralisation. Whether this biological transport facilitates fresh organic matter assimilation by the metazoan lower part of the food web through niche establishment (i.e., ecosystem engineering or rather deprives them from food sources, is so far unclear. We investigated the effects of the ecosystem engineers Lanice conchilega (bio-irrigator and Abra alba (bioturbator compared to abiotic physical mixing events on survival and food uptake of nematodes after a simulated phytoplankton bloom. The (13C labelled diatom Skeletonema costatum was added to 4 treatments: (1 microcosms containing the bioturbator, (2 microcosms containing the bio-irrigator, (3 control microcosms and (4 microcosms with abiotic manual surface mixing. Nematode survival and subsurface peaks in nematode density profiles were most pronounced in the bio-irrigator treatment. However, nematode specific uptake (Δδ(13C of the added diatoms was highest in the physical mixing treatment, where macrobenthos was absent and the diatom (13C was homogenised. Overall, nematodes fed preferentially on bulk sedimentary organic material rather than the added diatoms. The total C budget (µg C m(-2, which included TO(13C remaining in the sediment, respiration, nematode and macrobenthic uptake, highlighted the limited assimilation by the metazoan benthos and the major role of bacterial respiration. In summary, bioturbation and especially bio-irrigation facilitated the lower trophic levels mainly over the long-term through niche establishment. Since the freshly added diatoms represented only a limited food

  2. Global Patterns in Ecological Indicators of Marine Food Webs: A Modelling Approach

    Science.gov (United States)

    Heymans, Johanna Jacomina; Coll, Marta; Libralato, Simone; Morissette, Lyne; Christensen, Villy

    2014-01-01

    Background Ecological attributes estimated from food web models have the potential to be indicators of good environmental status given their capabilities to describe redundancy, food web changes, and sensitivity to fishing. They can be used as a baseline to show how they might be modified in the future with human impacts such as climate change, acidification, eutrophication, or overfishing. Methodology In this study ecological network analysis indicators of 105 marine food web models were tested for variation with traits such as ecosystem type, latitude, ocean basin, depth, size, time period, and exploitation state, whilst also considering structural properties of the models such as number of linkages, number of living functional groups or total number of functional groups as covariate factors. Principal findings Eight indicators were robust to model construction: relative ascendency; relative overhead; redundancy; total systems throughput (TST); primary production/TST; consumption/TST; export/TST; and total biomass of the community. Large-scale differences were seen in the ecosystems of the Atlantic and Pacific Oceans, with the Western Atlantic being more complex with an increased ability to mitigate impacts, while the Eastern Atlantic showed lower internal complexity. In addition, the Eastern Pacific was less organised than the Eastern Atlantic although both of these systems had increased primary production as eastern boundary current systems. Differences by ecosystem type highlighted coral reefs as having the largest energy flow and total biomass per unit of surface, while lagoons, estuaries, and bays had lower transfer efficiencies and higher recycling. These differences prevailed over time, although some traits changed with fishing intensity. Keystone groups were mainly higher trophic level species with mostly top-down effects, while structural/dominant groups were mainly lower trophic level groups (benthic primary producers such as seagrass and macroalgae

  3. Global patterns in ecological indicators of marine food webs: a modelling approach.

    Directory of Open Access Journals (Sweden)

    Johanna Jacomina Heymans

    Full Text Available BACKGROUND: Ecological attributes estimated from food web models have the potential to be indicators of good environmental status given their capabilities to describe redundancy, food web changes, and sensitivity to fishing. They can be used as a baseline to show how they might be modified in the future with human impacts such as climate change, acidification, eutrophication, or overfishing. METHODOLOGY: In this study ecological network analysis indicators of 105 marine food web models were tested for variation with traits such as ecosystem type, latitude, ocean basin, depth, size, time period, and exploitation state, whilst also considering structural properties of the models such as number of linkages, number of living functional groups or total number of functional groups as covariate factors. PRINCIPAL FINDINGS: Eight indicators were robust to model construction: relative ascendency; relative overhead; redundancy; total systems throughput (TST; primary production/TST; consumption/TST; export/TST; and total biomass of the community. Large-scale differences were seen in the ecosystems of the Atlantic and Pacific Oceans, with the Western Atlantic being more complex with an increased ability to mitigate impacts, while the Eastern Atlantic showed lower internal complexity. In addition, the Eastern Pacific was less organised than the Eastern Atlantic although both of these systems had increased primary production as eastern boundary current systems. Differences by ecosystem type highlighted coral reefs as having the largest energy flow and total biomass per unit of surface, while lagoons, estuaries, and bays had lower transfer efficiencies and higher recycling. These differences prevailed over time, although some traits changed with fishing intensity. Keystone groups were mainly higher trophic level species with mostly top-down effects, while structural/dominant groups were mainly lower trophic level groups (benthic primary producers such as

  4. Mercury bioaccumulation along food webs in temperate aquatic ecosystems colonized by aquatic macrophytes in south western France.

    Science.gov (United States)

    Gentès, Sophie; Maury-Brachet, Régine; Guyoneaud, Rémy; Monperrus, Mathilde; André, Jean-Marc; Davail, Stéphane; Legeay, Alexia

    2013-05-01

    Mercury (Hg) is considered as an important pollutant for aquatic systems as its organic form, methylmercury (MeHg), is easily bioaccumulated and bioamplified along food webs. In various ecosystems, aquatic periphyton associated with macrophyte was identified as an important place for Hg storage and methylation by microorganisms. Our study concerns temperate aquatic ecosystems (South Western France) colonized by invasive macrophytes and characterized by high mercury methylation potentials. This work establishes original data concerning Hg bioaccumulation in organisms (plants, crustaceans, molluscs and fish) from five contrasting ecosystems. For low trophic level species, total Hg (THg) concentrations were low (from 27±2ngTHgg(-1)dw in asiatic clam Corbicula fluminea to 418±114ngTHgg(-1)dw in crayfish Procambarus clarkii). THg concentrations in some carnivorous fish (high trophic level) were close to or exceeded the International Marketing Level (IML) with values ranging from 1049±220ngTHgg(-1)dw in pike perch muscle (Sander lucioperca) to 3910±1307ngTHgg(-1)dw in eel muscle (Anguilla Anguilla). Trophic levels for the individuals were also evaluated through stable isotope analysis, and linked to Hg concentrations of organisms. A significant Hg biomagnification (r(2)= 0.9) was observed in the Aureilhan lake, despite the absence of top predator fish. For this site, Ludwigia sp. periphyton, as an entry point of Hg into food webs, is a serious hypothesis which remains to be confirmed. This study provides a first investigation of Hg transfer in the ecosystems of south western France and allows the assessment of the risk associated with the presence of Hg in aquatic food webs. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. Stratification-Based Outlier Detection over the Deep Web.

    Science.gov (United States)

    Xian, Xuefeng; Zhao, Pengpeng; Sheng, Victor S; Fang, Ligang; Gu, Caidong; Yang, Yuanfeng; Cui, Zhiming

    2016-01-01

    For many applications, finding rare instances or outliers can be more interesting than finding common patterns. Existing work in outlier detection never considers the context of deep web. In this paper, we argue that, for many scenarios, it is more meaningful to detect outliers over deep web. In the context of deep web, users must submit queries through a query interface to retrieve corresponding data. Therefore, traditional data mining methods cannot be directly applied. The primary contribution of this paper is to develop a new data mining method for outlier detection over deep web. In our approach, the query space of a deep web data source is stratified based on a pilot sample. Neighborhood sampling and uncertainty sampling are developed in this paper with the goal of improving recall and precision based on stratification. Finally, a careful performance evaluation of our algorithm confirms that our approach can effectively detect outliers in deep web.

  6. Stable isotope analysis of a newly established macrofaunal food web 1.5 years after the Hebei Spirit oil spill

    International Nuclear Information System (INIS)

    Han, Eunah; Park, Hyun Je; Bergamino, Leandro; Choi, Kwang-Sik; Choy, Eun Jung; Yu, Ok Hwan; Lee, Tae Won; Park, Heung-Sik; Shim, Won Joon; Kang, Chang-Keun

    2015-01-01

    Highlights: • We examined trophic structure in a newly established community after an oil spill. • This is the most extensive in situ isotopic analysis on an oiled benthic community. • Consumer-food source δ 13 C and δ 15 N rejected influx of petroleum into the community. • A novel circular statistics rejected trophic niche change of major feeding guilds. • Prevalence of omnivory and trophic plasticity may promote the recovery process. - Abstract: We examined trophic relationships in a newly established community 1.5 years after the Hebei Spirit oil spill on the west coast of Korea. Carbon and nitrogen stable isotope ratios in consumers and their potential food sources were compared between the oil-spill site and reference site, located 13.5 km from the oil-spill spot. The isotopic mixing model and a novel circular statistics rejected the influx of petrogenic carbon into the community and identified spatial consistencies such as the high contributions of microphytobenthos, food-chain length, and the isotopic niche of each feeding guild between sites. We suggested that high level of trophic plasticity and the prevalence of omnivory of consumers may promote the robustness of food web against the oil contamination. Furthermore, we highlighted the need of holistic approaches including different functional groups to quantify changes in the food web structure and assess the influence of different perturbations including oil spill

  7. Recall Latencies, Confidence, and Output Positions of True and False Memories: Implications for Recall and Metamemory Theories

    Science.gov (United States)

    Jou, Jerwen

    2008-01-01

    Recall latency, recall accuracy rate, and recall confidence were examined in free recall as a function of recall output serial position using a modified Deese-Roediger-McDermott paradigm to test a strength-based theory against the dual-retrieval process theory of recall output sequence. The strength theory predicts the item output sequence to be…

  8. Time Limits : Effects on Recall

    OpenAIRE

    Hirano, Kinue

    2000-01-01

    This study investigates the effects of differing time limits and the level of language proficiency on the written recalls of 66 Japanese EFL undergraduates. Results showed that different time limits affected total recall, but not main ideas recalled. Regardless of proficiency level, the 20-minute group (Group 2) recalled a greater number of idea units than the 8-minute group (Group 1). However, no significant difference was found between Groups 1 and 2 regarding the recall of main ideas, alth...

  9. Different transfer pathways of an organochlorine pesticide across marine tropical food webs assessed with stable isotope analysis.

    Directory of Open Access Journals (Sweden)

    Charlotte R Dromard

    Full Text Available Chlordecone is a persistent organochlorine pesticide used in the banana fields of the French West Indies from 1972 to 1993. Three marine habitats (mangroves, seagrass beds and coral reefs of two study sites located downstream contaminated rivers were chosen to evaluate the level of contamination of marine food webs. On each habitat, the food chain collected included suspended organic matter, primary producers (macroalgae, algal turf, seagrass, zooplankton, symbiotic organisms (corals, sea anemones, primary consumers (herbivores, suspension feeders, biofilm feeders, omnivores and detritivores (lobsters, fish, secondary consumers (carnivores 1: invertebrate feeders, planktivores and tertiary consumers (carnivores 2: invertebrate and fish feeders, piscivores. Log-linear regressions of the concentrations of chlordecone versus nitrogen isotopic ratios (δ15N were used to assess the bioaccumulation of chlordecone along trophic food webs. At each site, bioconcentration and bioamplification take part on the transfer of chlordecone in marine organisms. In mangroves (i.e. close to the source of pollution, lower trophic magnification factors (TMF indicated that bioconcentration prevailed over bioamplification phenomenon. The opposite phenomenon appeared on coral reefs in which bioconcentration processes were less important and bioamplification pathway became dominant. Far from the source of pollution, molecules of chlordecone seemed to be transfered to organisms mostly via trophic interactions rather than water contact.

  10. Mercury and selenium accumulation in the Colorado River food web, Grand Canyon, USA

    Science.gov (United States)

    Walters, David M.; E.J. Rosi-Marshall,; Kennedy, Theodore A.; W.F. Cross,; C.V. Baxter,

    2015-01-01

    Mercury (Hg) and selenium (Se) biomagnify in aquatic food webs and are toxic to fish and wildlife. The authors measured Hg and Se in organic matter, invertebrates, and fishes in the Colorado River food web at sites spanning 387 river km downstream of Glen Canyon Dam (AZ, USA). Concentrations were relatively high among sites compared with other large rivers (mean wet wt for 6 fishes was 0.17–1.59 μg g–1 Hg and 1.35–2.65 μg g–1 Se), but consistent longitudinal patterns in Hg or Se concentrations relative to the dam were lacking. Mercury increased (slope = 0.147) with δ15N, a metric of trophic position, indicating biomagnification similar to that observed in other freshwater systems. Organisms regularly exceeded exposure risk thresholds for wildlife and humans (6–100% and 56–100% of samples for Hg and Se, respectfully, among risk thresholds). In the Colorado River, Grand Canyon, Hg and Se concentrations pose exposure risks for fish, wildlife, and humans, and the findings of the present study add to a growing body of evidence showing that remote ecosystems are vulnerable to long-range transport and subsequent bioaccumulation of contaminants. Management of exposure risks in Grand Canyon will remain a challenge, as sources and transport mechanisms of Hg and Se extend far beyond park boundaries. Environ Toxicol Chem2015;9999:1–10

  11. Fast and accurate approaches for large-scale, automated mapping of food diaries on food composition tables

    DEFF Research Database (Denmark)

    Lamarine, Marc; Hager, Jörg; Saris, Wim H M

    2018-01-01

    the EuroFIR resource. Two approaches were tested: the first was based solely on food name similarity (fuzzy matching). The second used a machine learning approach (C5.0 classifier) combining both fuzzy matching and food energy. We tested mapping food items using their original names and also an English...... not lead to any improvements compared to the fuzzy matching. However, it could increase substantially the recall rate for food items without any clear equivalent in the FCTs (+7 and +20% when mapping items using their original or English-translated names). Our approaches have been implemented as R packages...... and are freely available from GitHub. Conclusion: This study is the first to provide automated approaches for large-scale food item mapping onto FCTs. We demonstrate that both high precision and recall can be achieved. Our solutions can be used with any FCT and do not require any programming background...

  12. Writing superiority in cued recall

    Directory of Open Access Journals (Sweden)

    Carina eFueller

    2013-10-01

    Full Text Available In list learning paradigms with free recall, written recall has been found to be less susceptible to intrusions of related concepts than spoken recall when the list items had been visually presented. This effect has been ascribed to the use of stored orthographic representations from the study phase during written recall (Kellogg, 2001. In other memory retrieval paradigms, either better recall for modality-congruent items or an input-independent writing superiority effect have been found (Grabowski, 2005. In a series of four experiments using a paired associate (PA learning paradigm we tested (a whether output modality effects on verbal recall can be replicated in a paradigm that does not involve the rejection of semantically related intrusion words, (b whether a possible superiority for written recall was due to a slower response onset for writing as compared to speaking in immediate recall, and (c whether the performance in PA word recall was correlated with performance in an additional episodic memory task. We found better written recall in the first half of the recall phase, irrespective of the modality in which the material was presented upon encoding. An explanation based on longer response latencies for writing and hence more time for retrieval could be ruled out by showing that the effect persisted in delayed response versions of the task. Although there was some evidence that stored additional episodic information may contribute to the successful retrieval of associate words, this evidence was only found in the immediate response experiments and hence is most likely independent from the observed output modality effect. In sum, our results from a PA learning paradigm suggest that superior performance for written versus spoken recall cannot be (solely explained in terms of additional access to stored orthographic representations from the encoding phase. Our findings rather suggest a general writing-superiority effect at the time of memory

  13. Precipitation and temperature drive seasonal variation in bioaccumulation of polycyclic aromatic hydrocarbons in the planktonic food webs of a subtropical shallow eutrophic lake in China.

    Science.gov (United States)

    Tao, Yuqiang; Yu, Jing; Xue, Bin; Yao, Shuchun; Wang, Sumin

    2017-04-01

    Hydrophobic organic contaminants (HOCs) are toxic and ubiquitous in aquatic environments and pose great risks to aquatic organisms. Bioaccumulation by plankton is the first step for HOCs to enter aquatic food webs. Trophic status is considered to dominate variations in bioaccumulation of HOCs in plankton in temperate and frigid deep oligotrophic waters. However, long-term driving factors for bioaccumulation of HOCs in planktonic food webs of subtropical shallow eutrophic waters have not been well investigated. China has the largest subtropical lake density in the Northern Hemisphere. Due to limited field data, long-term variations in the bioaccumulation of HOCs in these lakes are almost unknown. Here we take Lake Xuanwu as an example to investigate long-term variations in the bioaccumulation, and biomagnification of polycyclic aromatic hydrocarbon (PAHs) in planktonic food webs of subtropical shallow eutrophic lakes in China, and elucidate the driving factors. Our results indicate that temperature rather than nutrients dominates long-term dynamics of planktonic biomass in this lake. Precipitation significantly enhances the concentrations of the PAHs, and total suspended particles, and consequently affects the distribution of the PAHs in the water column. Biomass dilution induced by temperature dominates bioaccumulation of the PAHs by both phytoplankton and zooplankton (copepods and cladocerans). Biomagnification of the PAHs from phytoplankton to zooplankton is positively correlated with temperature. Our study suggests that temperature and precipitation drive long-term variations in the bioaccumulation of the PAHs in the planktonic food webs of this subtropical shallow eutrophic lake. Lake Xuanwu has a similar mean annual temperature, annual precipitation, sunshine duration, and nutrient levels as other subtropical shallow eutrophic lakes in China. This study may also help to understand the bioaccumulation of HOCs in planktonic food webs of other subtropical shallow

  14. Mathematical modelling and analysis for a three-tiered microbial food web in a chemostat

    Directory of Open Access Journals (Sweden)

    Miled El hajji

    2017-10-01

    Full Text Available In this article, we present a mathematical six-dimensional dynamical system involving a three-tiered microbial food web without maintenance. We give a qualitative analysis of the model, and an analysis of the local stability of equilibrium points. Under general assumptions of monotonicity, we prove the uniqueness and the local stability of the positive equilibrium point corresponding to the persistence of the three bacteria. Possibilities of periodic orbits are not excluded and asymptotic coexistence is satisfied.

  15. Selective alteration of soil food web components by invasive Giant goldenrod (Solidago gigantea) in two distinct habitat types

    NARCIS (Netherlands)

    Quist, C.W.; Vervoort, M.T.W.; Megen, van H.H.B.; Gort, G.; Bakker, J.; Putten, van der W.H.; Helder, J.

    2014-01-01

    Apart from relatively well-studied aboveground effects, invasive plant species will also impact the soil food web. So far, most research has been focusing on primary decomposers, while studies on effects at higher trophic levels are relatively scarce. Giant goldenrod Solidago gigantea, native to

  16. Selective alteration of soil food web components by invasive giant goldenrod Solidago gigantea in two distinct habitat types

    NARCIS (Netherlands)

    Quist, C.W.; Vervoort, M.T.W.; Van Megen, H.; Gort, G.; Bakker, J.; Van der Putten, W.H.; Helder, J.

    2014-01-01

    Apart from relatively well-studied aboveground effects, invasive plant species will also impact the soil food web. So far, most research has been focusing on primary decomposers, while studies on effects at higher trophic levels are relatively scarce. Giant goldenrod Solidago gigantea, native to

  17. Validity of self-reported lunch recalls in Swedish school children aged 6-8 years.

    Science.gov (United States)

    Hunsberger, Monica; Pena, Pablo; Lissner, Lauren; Grafström, Lisen; Vanaelst, Barbara; Börnhorst, Claudia; Pala, Valeria; Eiben, Gabriele

    2013-09-18

    Previous studies have suggested that young children are inaccurate reporters of dietary intake. The purpose of this study was to validate a single recall of the previous day's school lunch reported by 6-8 year old Swedish children and to assess teacher-recorded intake of the same meal in a standardized food journal. An additional research question was whether parents could report their child's intake of the previous day's lunch. Subjects constituted a convenience sample from the large, multi-country study Identification and prevention of Dietary- and lifestyle-induced health EFfects In Children and infantS (IDEFICS). Validations of both children's recalls and teachers' records were made by comparing results with the duplicate plate reference method. Twenty-five children (12 boys/13 girls) aged 6-8 years participated in the validation study at one school in western Sweden. Children were accurate self-reporters of their dietary intake at lunch, with no significant difference between reported and weighed intake (Mean difference (SD): 7(50) kcals, p=0.49). Teachers significantly over-reported intake (Mean difference (SD): 65(79) kcals, p=0.01). For both methods, child-reported and teacher-recorded, correlations with weighed intake were strong (Pearson's correlations r=0.92, pteacher-records and weighed intakes. Foods were recalled by children with a food-match rate of 90%. In all cases parents themselves were unable to report on quantities consumed and only four of 25 children had parents with knowledge regarding food items consumed. Children 6-8 years of age accurately recalled their school lunch intake for one occasion while teachers recorded with less accuracy. Our findings suggest that children as young as six years of age may be better able to report on their dietary intake than previously suggested, at least for one main meal at school. Teacher-recorded intake provides a satisfactory estimate but with greater systematic deviation from the weighed intake

  18. Web page of the Ibero-American laboratories network of radioactivity analysis in foods: a tool for inter regional diffusion

    International Nuclear Information System (INIS)

    Melo Ferreira, Ana C. de; Osores, Jose M.; Fernandez Gomez, Isis M.; Iglicki, Flora A.; Vazquez Bolanos, Luis R.; Romero, Maria de L.; Aguirre Gomez, Jaime; Flores, Yasmine

    2008-01-01

    One objective of the thematic networks is the exchanges of knowledge among participants, for this reason, actions focused to the diffusion of their respective work are prioritized, evidencing the result of the cooperation among the participant groups and also among different networks. The Ibero-American Laboratories Network of Radioactivity Analysis in Foods (RILARA) was constituted in 2007, and one of the first actions carried out in this framework, was the design and conformation of a web page. The web pages have become a powerful means for diffusion of specialized information. Their power, as well as their continuous upgrading and the specificity of the topics that can develop, allow the user to obtain fast information on a wide range of products, services and organizations at local and world level. The main objective of the RILARA web page is to provide updated relevant information to interested specialists in the subject and also to public in general, about the work developed by the network laboratories regarding the control of radioactive pollutants in foods and related scientific issues. This web has been developed based on a Content Management Systems that helps to eliminate potential barriers to the communication web, reducing the creation costs, contribution and maintenance of the content. The tool used for its design is very effective to be used in the process of teaching, learning and for the organization of the information. This paper describes how was conceived the design of this web page, the information that contains and how can be accessed and/or to include any contribution, the value of this page depends directly on the grade of updating of the available contents so that it can be useful and attractive to the users. (author)

  19. Relative validity and reproducibility of a food frequency questionnaire used in pregnant women from a rural area of China.

    Science.gov (United States)

    Li, Min; Halldorsson, Thorhallur I; Bjerregaard, Anne A; Che, Yan; Mao, Yanyan; Hu, Wenfu; Wang, Yu; Zhou, Weijin; Olsen, Sjúrdur F; Strøm, Marin

    2014-11-01

    Food frequency questionnaires are relatively inexpensive, easy and quick to administer, but the construction of a food frequency questionnaire that can capture Chinese food habits is challenging given the diverse lifestyle and eating habits in different parts of the country. The aim of this study was to assess the validity and reproducibility of a self-administered food frequency questionnaire against a 3-day dietary recall in a rural region of western China. Prospective cohort study. Chinese maternal and child healthcare hospital. A total of 168 healthy pregnant women. Pregnant women completed a food frequency questionnaire at 16-24 weeks gestation, and again at 29-31 weeks; during weeks 26-27 they completed a 3-day dietary recall. In general, mean intake was higher when assessed with food frequency questionnaires compared with dietary recall. Spearman and intra-class correlation coefficients between the two food frequency questionnaires ranged from 0.31 to 0.69 and from 0.27 to 0.79, respectively. For the second food frequency questionnaire and the dietary recall, the crude and de-attenuated Spearman correlations ranged from 0.12 to 0.55 and 0.14 to 0.58, respectively. The correlation both between the two food frequency questionnaires and between the second food frequency questionnaire and the dietary recall decreased after adjustment for energy. Ranking women, 31-57% and 1-8% were classified into the same and the opposite quartile, respectively, by both food frequency questionnaires; 30-45% and 1-11% were classified into the same and the opposite quartile respectively for the second food frequency questionnaire and dietary recall. The food frequency questionnaire showed good reproducibility and correlations with dietary recall; it is useful for ranking study participants according to dietary intake, which is of great importance to future etiological studies in this cohort. © 2014 Nordic Federation of Societies of Obstetrics and Gynecology.

  20. Radiocarbon evidence that carbon from the Deepwater Horizon spill entered the planktonic food web of the Gulf of Mexico

    International Nuclear Information System (INIS)

    Chanton, J P; Wilson, R M; Mickle, A; Cherrier, J; Sarkodee-Adoo, J; Bosman, S; Graham, W M

    2012-01-01

    The Deepwater Horizon (Macondo) oil spill released large volumes of oil and gas of distinct carbon isotopic composition to the northern Gulf of Mexico, allowing Graham et al (2010 Environ. Res. Lett. 5 045301) to use stable carbon isotopes (δ 13 C) to infer the introduction of spilled oil into the planktonic food web. Surface ocean organic production and measured oil are separated by 5–7‰ in stable carbon isotope (δ 13 C) space, while in radiocarbon (Δ 14 C) space these two potential sources are separated by more than 1000‰. Thus radiocarbon isotopes provide a more sensitive tracer by which to infer possible introduction of Macondo oil into the food web. We measured Δ 14 C and δ 13 C in plankton collected from within 100 km of the spill site as well as in coastal and offshore DIC (dissolved inorganic carbon or ΣCO 2 ) to constrain surface production values. On average, plankton values were depleted in 14 C relative to surface DIC, and we found a significant linear correlation between Δ 14 C and δ 13 C in plankton. Cumulatively, these results are consistent with the hypothesis that carbon released from the Deepwater Horizon spill contributed to the offshore planktonic food web. Our results support the findings of Graham et al (2010 Environ. Res. Lett. 5 045301), but we infer that methane input may be important. (letter)