WorldWideScience

Sample records for eutrophication examining linkages

  1. Examining the Linkage Between FRAMES and GMS

    Energy Technology Data Exchange (ETDEWEB)

    Whelan, Gene; Castleton, Karl J.

    2006-02-13

    Because GMS provides so many features, of which some are also addressed by FRAMES, it could represent a platform to link to FRAMES, or FRAMES could represent a platform to link to GMS. The focus of this summary is to examine the strengths and weaknesses of the potential linkage direction and provide recommendations for the linkage between FRAMES and GMS.

  2. Eutrophication.

    Science.gov (United States)

    Porcella, Donald B.

    1978-01-01

    Presents a literature review of lake eutrophication, covering publications of 1976-77. This review covers: (1) nutrients sources; (2) lake manipulation and nutrient control; (3) aquatic macrophytes; and (4) nutrients, productivity, and biological interactions. A list of 69 references is also presented. (HM)

  3. Nutrient profiles in the everglades: examination along the eutrophication gradient.

    Science.gov (United States)

    Vaithiyanathan, P; Richardson, C J

    1997-10-07

    We examined the concentration profiles of nutrients in the surface water, soil and pore water along the eutrophication gradient of the Water Conservation Area-2A (WCA-2A) in the northern Everglades. Phosphorus levels in the surface waters contributed by the agricultural runoff showed an exponential decrease downstream of the inflow structures attaining background values of 7-12, 7-9 and 5-6 micrograms l-1 of TP, TDP and PO4-P, respectively, at distances of 8-10 km. The pore water PO4-P concentration in the oligotrophic areas ranged between 5 and 10 micrograms l-1. Molar ratios of dissolved inorganic N and P suggest a possible switch in nutrient limitation in the surface water from P in the oligotrophic areas to N in the eutrophic areas (DIN:DIP approximately 5). External nutrient loading has also contributed to a three- to four-fold increase in soil TP concentration and enhanced pore water PO4-P in the northern marshes. Unlike P, C and N concentration in the soils remained fairly uniform along the eutrophication gradient. 210Pb dating of soil cores suggests that the increase in soil P concentration (from wetlands. Calcium supply from the underlying bedrock suggested from the surface and pore water chemical profiles has important consequences for P-cycling in the Everglades as Ca-bound P is the major form of inorganic P storage in the soils.

  4. Use of Coupled Eutrophication and Network Models for Examination of Fisheries and Eutrophication Processes

    National Research Council Canada - National Science Library

    Cerco, Carl F; Tillman, Dorothy H

    2008-01-01

    ...) was designed to be a flexible, widely applicable eutrophication model. Ecopath with Ecosim (EWE) is a freely distributed network model supported by the Fisheries Centre, University of British Columbia...

  5. Examining Linkages between Psychological Health Problems, Socio-Demographic Characteristics and Workplace Stressors in Pakistan's Academia

    Science.gov (United States)

    Khan, Anwar; Yusoff, Rosman Bin Md; Isa, Khairunesa Binti

    2016-01-01

    Scholarly work and research are globally known as stressful and challenging. Teachers may develop different psychological health problems once they are exposed to workplace stressors. Considering it as a serious issue of education sector, this study has examined the linkages between prevalent workplace stressors and psychological health problems…

  6. The status and characteristics of eutrophication in tropical coastal water.

    Science.gov (United States)

    Peyman, Nooshin; Tavakoly Sany, Seyedeh Belin; Tajfard, Mohammad; Hashim, Rosli; Rezayi, Majid; Karlen, David J

    2017-08-16

    A set of methodological tools was tested to assess the sensitivity of several ecological and biological indices to eutrophication while at the same time attempting to explore a linkage among pressures, classification assessment and drivers. Industrial discharges, harbor activities, natural interactions and river discharges are the pressures most related to the eutrophication process in tropical coastal water bodies. Among the eutrophication indices used, TRIX and operational indicators overestimated the eutrophication status in the study area, but EI and chl-a seems to be a rather responsive index to reflect the first stage of eutrophication. It is noteworthy that EI and chl-a showed better overall agreement with the ecological quality status (EcoQ) showing that probably it reflects the indirect relation of macrobenthic with water eutrophication in a better way. An ecological boundary of EI and chl-a from moderate to poor may be needed in order to explain the poor status of relatively eutrophic Klang Strait coastal sites.

  7. PLAB and UK graduates’ performance on MRCP(UK) and MRCGP examinations: data linkage study

    Science.gov (United States)

    Wakeford, Richard

    2014-01-01

    Objectives To assess whether international medical graduates passing the two examinations set by the Professional and Linguistic Assessments Board (PLAB1 and PLAB2) of the General Medical Council (GMC) are equivalent to UK graduates at the end of the first foundation year of medical training (F1), as the GMC requires, and if not, to assess what changes in the PLAB pass marks might produce equivalence. Design Data linkage of GMC PLAB performance data with data from the Royal Colleges of Physicians and the Royal College of General Practitioners on performance of PLAB graduates and UK graduates at the MRCP(UK) and MRCGP examinations. Setting Doctors in training for internal medicine or general practice in the United Kingdom. Participants 7829, 5135, and 4387 PLAB graduates on their first attempt at MRCP(UK) Part 1, Part 2, and PACES assessments from 2001 to 2012 compared with 18 532, 14 094, and 14 376 UK graduates taking the same assessments; 3160 PLAB1 graduates making their first attempt at the MRCGP AKT during 2007-12 compared with 14 235 UK graduates; and 1411 PLAB2 graduates making their first attempt at the MRCGP CSA during 2010-12 compared with 6935 UK graduates. Main outcome measures Performance at MRCP(UK) Part 1, Part 2, and PACES assessments, and MRCGP AKT and CSA assessments in relation to performance on PLAB1 and PLAB2 assessments, as well as to International English Language Testing System (IELTS) scores. MRCP(UK), MRCGP, and PLAB results were analysed as marks relative to the pass mark at the first attempt. Results PLAB1 marks were a valid predictor of MRCP(UK) Part 1, MRCP(UK) Part 2, and MRCGP AKT (r=0.521, 0.390, and 0.490; all PIELTS scores correlated significantly with later performance, multiple regression showing that the effect of PLAB1 (β=0.496) was much stronger than the effect of IELTS (β=0.086). Changes to PLAB pass marks that would result in international medical graduate and UK medical graduate equivalence were assessed in two

  8. PLAB and UK graduates' performance on MRCP(UK) and MRCGP examinations: data linkage study.

    Science.gov (United States)

    McManus, I C; Wakeford, Richard

    2014-04-17

    To assess whether international medical graduates passing the two examinations set by the Professional and Linguistic Assessments Board (PLAB1 and PLAB2) of the General Medical Council (GMC) are equivalent to UK graduates at the end of the first foundation year of medical training (F1), as the GMC requires, and if not, to assess what changes in the PLAB pass marks might produce equivalence. Data linkage of GMC PLAB performance data with data from the Royal Colleges of Physicians and the Royal College of General Practitioners on performance of PLAB graduates and UK graduates at the MRCP(UK) and MRCGP examinations. Doctors in training for internal medicine or general practice in the United Kingdom. 7829, 5135, and 4387 PLAB graduates on their first attempt at MRCP(UK) Part 1, Part 2, and PACES assessments from 2001 to 2012 compared with 18,532, 14,094, and 14,376 UK graduates taking the same assessments; 3160 PLAB1 graduates making their first attempt at the MRCGP AKT during 2007-12 compared with 14,235 UK graduates; and 1411 PLAB2 graduates making their first attempt at the MRCGP CSA during 2010-12 compared with 6935 UK graduates. Performance at MRCP(UK) Part 1, Part 2, and PACES assessments, and MRCGP AKT and CSA assessments in relation to performance on PLAB1 and PLAB2 assessments, as well as to International English Language Testing System (IELTS) scores. MRCP(UK), MRCGP, and PLAB results were analysed as marks relative to the pass mark at the first attempt. PLAB1 marks were a valid predictor of MRCP(UK) Part 1, MRCP(UK) Part 2, and MRCGP AKT (r=0.521, 0.390, and 0.490; all PIELTS scores correlated significantly with later performance, multiple regression showing that the effect of PLAB1 (β=0.496) was much stronger than the effect of IELTS (β=0.086). Changes to PLAB pass marks that would result in international medical graduate and UK medical graduate equivalence were assessed in two ways. Method 1 adjusted PLAB pass marks to equate median performance of PLAB

  9. Linkages to Survival : : An Examination of the Reproductive and Maternal Health Continuum of Care

    OpenAIRE

    McDougal, Lotus Padma

    2014-01-01

    Background : Each year, an estimated 287,000 women and 3 million newborns in low and middle income countries die of largely preventable causes. Global organizations have adopted a continuum of care model to mitigate these deaths, in which health interventions are conceptualized as a continuous stream of services. This approach remains untested in practice, however. This research aims to explore utilization and linkages within the reproductive and maternal health continuum of care (RMH CoC), a...

  10. Estimating time-varying RSA to examine psychophysiological linkage of marital dyads.

    Science.gov (United States)

    Gates, Kathleen M; Gatzke-Kopp, Lisa M; Sandsten, Maria; Blandon, Alysia Y

    2015-08-01

    One of the primary tenets of polyvagal theory dictates that parasympathetic influence on heart rate, often estimated by respiratory sinus arrhythmia (RSA), shifts rapidly in response to changing environmental demands. The current standard analytic approach of aggregating RSA estimates across time to arrive at one value fails to capture this dynamic property within individuals. By utilizing recent methodological developments that enable precise RSA estimates at smaller time intervals, we demonstrate the utility of computing time-varying RSA for assessing psychophysiological linkage (or synchrony) in husband-wife dyads using time-locked data collected in a naturalistic setting. © 2015 Society for Psychophysiological Research.

  11. Suicide in Newfoundland and Labrador: a linkage study using medical examiner and vital statistics data.

    Science.gov (United States)

    Edwards, Nicole; Alaghehbandan, Reza; MacDonald, Don; Sikdar, Khokan; Collins, Kayla; Avis, Simon

    2008-04-01

    To examine suicide epidemiology in Newfoundland and Labrador from 1997 to 2001. Data from the Office of the Chief Medical Examiner (CME) were linked with data derived from the Canadian Vital Statistics Death Database. Ninety-five percent confidence intervals (CI) were calculated to assess variation of rates. We used the chi-square test to compare categorical data. The CME recorded 225 suicide deaths, compared with 187 in the Canadian Vital Statistics Death Database. Most deaths not coded as suicide in the national database were coded as accidental. Using the CME data, the overall suicide rate was 9.5/100000, aged 10 years and older. The rate among males (15.8/100 000, 95% CI, 10.7 to 20.8) was almost 5 times that of females (3.3/100000; 95% CI, 1.0 to 5.5). Age-standardized rates decreased over the study period, from 10.9 to 8.0/100000; however, the difference was not significant. The proportionate mortality ratio for suicide deaths was highest among those aged 10 to 19 years (20.0%) and decreased with age. The suicide rate was highest among those aged 50 to 59 years. The rate for unpartnered individuals (17.0/100000, 95% CI, 10.7 to 23.0) was significantly higher, compared with partnered individuals (5.1/100000; 95%CI, 2.5 to 7.8). Males used more violent methods than females. Suicide was significantly higher in Labrador (27.7/100000, 95% CI, 18.4 to 37.0), an area with a higher Aboriginal population, compared with the island of Newfoundland (8.5/100000, 95% CI, 7.3 to 9.7). Psychiatric illness was the most common predisposing factor. Suicide deaths are highest among males, unpartnered individuals, and individuals with psychiatric disorders.

  12. Coastal marine eutrophication assessment: a review on data analysis.

    Science.gov (United States)

    Kitsiou, Dimitra; Karydis, Michael

    2011-05-01

    A wide variety of data analysis techniques have been applied for quantitative assessment of coastal marine eutrophication. Indicators for assessing eutrophication and frequency distributions have been used to develop scales for characterizing oligotrophy and eutrophication. Numerical classification has also contributed to the assessment of eutrophic trends by grouping sampling sites of similar trophic conditions. Applications of eutrophication assessment based on Principal Component Analysis and Multidimensional Scaling have also been carried out. In addition, the rapid development of Geographical Information Systems has provided the framework for applications of spatial methods and mapping techniques on eutrophication studies. Satellite data have also contributed to eutrophication assessment especially at large scale. Multiple criteria analysis methods can integrate eutrophication variables together with socio-economic parameters providing a holistic approach particularly useful to policy makers. As the current concept of eutrophication problems is to be examined as part of a coastal management approach, more complex quantitative procedures are needed to provide a platform useful for implementation of environmental policy. The present work reviews methods of data analysis used for the assessment of coastal marine eutrophication. The difficulties in applying these methods on data collected from the marine environment are discussed as well as the future perspectives of spatial and multiple criteria choice methods. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Cultural eutrophication: perspectives and prospects

    OpenAIRE

    Wassmann, Paul

    2005-01-01

    History of cultural eutrophication. Cultural eutrophication is old as Homo sapiens. In particular after the introduction of agriculture and larger settlements eutrophication has been mans faithful companion. During the pre-agricultural hunting and picking stage only probably a couple million humans inhabited the world and cultural eutrophication was negligible. The 3 orders of magnitude increase in population has changed this considerably. Human population growth an...

  14. Eutrophication in a Beaker.

    Science.gov (United States)

    Gill, John; Markby, Jane

    1991-01-01

    A method for demonstrating eutrophication that can be used as a simple illustration of the phenomenon or as a basis for problem-solving activities is presented. A sample worksheet with procedures for this activity and discussion questions is included. (Author/KR)

  15. Eutrophication, A Natural Process.

    Science.gov (United States)

    Monsour, William

    This environmental education learning unit deals with the topic of eutrophication. The unit is designed to allow secondary teachers of science, language arts, and social studies to use it as supplementary material in their classroom. Teacher information, unit objectives, the unit text, and appendices are included. The teacher information section…

  16. Examination of X chromosome markers in Rett syndrome: Exclusion mapping with a novel variation on multilocus linkage analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ellison, K.A.; Fill, C.P. (Baylor College of Medicine, Houston, TX (United States)); Terwililger, J.; Percy, A.K.; Zobhbi, H. (Columbia University, NY (United States)); DeGennaro, L.J.; Ott, J. (University of Massachusetts Medical School, Worcester (United States)); Anvret, M.; Martin-Gallardo, A. (National Institutes of Health, Bethesda, MD (United States))

    1992-02-01

    Rett syndrome is a neurologic disorder characterized by early normal development followed by regression, acquired deceleration of head growth, autism, ataxia, and sterotypic hand movements. The exclusive occurrence of the syndrome in females and the occurrence of a few familial cases with inheritance through maternal lines suggest that this disorder is most likely secondary to a mutation on the X chromosome. To address this hypothesis and to identify candidate regions for the Rett syndrome gene locus, genotypic analysis was performed in two families with maternally related affected half-sisters by using 63 DNA markers from the X chromosome. Nineteen of the loci studied were chosen for multipoint linkage analysis because they have been previously genetically mapped using a large number of meioses from reference families. Using the exclusion criterion of a lod score less than [minus]2, the authors were able to exclude the region between the Duchenne muscular dystrophy locus and the DXS456 locus. This region extends from Xp21.2 to Xq21-q23. The use of the multipoint linkage analysis approach outlined in this study should allow the exclusion of additional regions of the X chromosome as new markers are analyzed.

  17. An ever-closer union? Examining the evolution of linkages of European equity markets via minimum spanning trees

    Science.gov (United States)

    Gilmore, Claire G.; Lucey, Brian M.; Boscia, Marian

    2008-11-01

    The concept of a minimum spanning tree (MST) is used to study the process of comovements for 21 European Union stock market indices. We show how the minimum spanning tree and its related hierarchical tree evolve over time and describe the dynamics. Over the period studied, 1999-2006, the French equity market provides the main linkages in the system. The 2004 Accession states are more loosely connected to the other markets; they form two groupings, with the Czech Republic, Hungary, and Poland having tighter links to the main markets than the remaining Accession markets. Shorter distances between markets indicate a potential reduction of the benefits of international portfolio diversification in European markets, with the possible exception of those markets at the outer limits of the MST.

  18. Is Lake Chabot Eutrophic?

    Science.gov (United States)

    Pellegrini, K.; Logan, J.; Esterlis, P.; Lew, A.; Nguyen, M.

    2013-12-01

    Introduction/Abstract: Lake Chabot is an integral part of the East Bay watershed that provides habitats for animals and recreation for humans year-round. Lake Chabot has been in danger of eutrophication due to excessive dumping of phosphorous and nitrogen into the water from the fertilizers of nearby golf courses and neighboring houses. If the lake turned out to be eutrophified, it could seriously impact what is currently the standby emergency water supply for many Castro Valley residents. Eutrophication is the excessive richness of nutrients such as nitrogen and phosphorus in a lake, usually as a result of runoff. This buildup of nutrients causes algal blooms. The algae uses up most of the oxygen in the water, and when it dies, it causes the lake to hypoxify. The fish in the lake can't breathe, and consequently suffocate. Other oxygen-dependant aquatic creatures die off as well. Needless to say, the eutrophication of a lake is bad news for the wildlife that lives in or around it. The level of eutrophication in our area in Northern California tends to increase during the late spring/early summer months, so our crew went out and took samples of Lake Chabot on June 2. We focused on the area of the lake where the water enters, known on the map as Honker Bay. We also took readings a ways down in deeper water for comparison's sake. Visually, the lake looked in bad shape. The water was a murky green that glimmered with particulate matter that swirled around the boat as we went by. In the Honker Bay region where we focused our testing, there were reeds bathed in algae that coated the surface of the lake in thick, swirling patterns. Surprisingly enough, however, our test results didn't reveal any extreme levels of phosphorous or nitrogen. They were slightly higher than usual, but not by any significant amount. The levels we found were high enough to stimulate plant and algae growth and promote eutrophication, but not enough to do any severe damage. After a briefing with a

  19. Mechanisms and assessment of water eutrophication*

    OpenAIRE

    Yang, Xiao-e; Wu, Xiang; Hao, Hu-lin; He, Zhen-li

    2008-01-01

    Water eutrophication has become a worldwide environmental problem in recent years, and understanding the mechanisms of water eutrophication will help for prevention and remediation of water eutrophication. In this paper, recent advances in current status and major mechanisms of water eutrophication, assessment and evaluation criteria, and the influencing factors were reviewed. Water eutrophication in lakes, reservoirs, estuaries and rivers is widespread all over the world and the severity is ...

  20. SELECTION OF CANDIDATE EUTROPHICATION MODELS FOR TOTAL MAXIMUM DAILY LOADS ANALYSES

    Science.gov (United States)

    A tiered approach was developed to evaluate candidate eutrophication models to select a common suite of models that could be used for Total Maximum Daily Loads (TMDL) analyses in estuaries, rivers, and lakes/reservoirs. Consideration for linkage to watershed models and ecologica...

  1. A bibliometric analysis of eutrophication literatures: an expanding and shifting focus.

    Science.gov (United States)

    Li, Xia; Nan, Ruiqi

    2017-07-01

    This paper examined the eutrophication literatures from 1998 to 2015 using bibliometric techniques basing on the database of Science Citation Index. Bibliometric techniques, social network analysis, and mapping knowledge domains in this paper were used. The results revealed that article was the most used document type accounting for 94.79% (14,006) of the records. With the rapid development of eutrophication domain after 2004, the annual article publishing amount also grew notably in each country, with the list of US tops. International cooperation was not enough to compare with that between institutions. An author keyword analysis showed that "phosphorus," "nutrients," "nitrogen," "water quality," "phytoplankton," and "sediment" were the most popular keywords. And it was also found that climate change, life cycle assessment, and chlorophyll a appear with high frequency in recent years, indicating that the eutrophication mechanism analysis might turn from uni-factor microresearch to multi-factor macroresearch, and the eutrophication management research tends to be whole-process management research. In addition, the future focuses of research directions, including (1) eutrophication and its ecosystem response, (2) eutrophication management, (3) eutrophication and climate change interactions, (4) eutrophication monitoring and forecast, and (5) ecological restoration of eutrophication. These findings are useful for the future endeavor of eutrophication academic research.

  2. Mechanisms and assessment of water eutrophication*

    Science.gov (United States)

    Yang, Xiao-e; Wu, Xiang; Hao, Hu-lin; He, Zhen-li

    2008-01-01

    Water eutrophication has become a worldwide environmental problem in recent years, and understanding the mechanisms of water eutrophication will help for prevention and remediation of water eutrophication. In this paper, recent advances in current status and major mechanisms of water eutrophication, assessment and evaluation criteria, and the influencing factors were reviewed. Water eutrophication in lakes, reservoirs, estuaries and rivers is widespread all over the world and the severity is increasing, especially in the developing countries like China. The assessment of water eutrophication has been advanced from simple individual parameters like total phosphorus, total nitrogen, etc., to comprehensive indexes like total nutrient status index. The major influencing factors on water eutrophication include nutrient enrichment, hydrodynamics, environmental factors such as temperature, salinity, carbon dioxide, element balance, etc., and microbial and biodiversity. The occurrence of water eutrophication is actually a complex function of all the possible influencing factors. The mechanisms of algal blooming are not fully understood and need to be further investigated. PMID:18357622

  3. Mechanisms and assessment of water eutrophication.

    Science.gov (United States)

    Yang, Xiao-e; Wu, Xiang; Hao, Hu-lin; He, Zhen-li

    2008-03-01

    Water eutrophication has become a worldwide environmental problem in recent years, and understanding the mechanisms of water eutrophication will help for prevention and remediation of water eutrophication. In this paper, recent advances in current status and major mechanisms of water eutrophication, assessment and evaluation criteria, and the influencing factors were reviewed. Water eutrophication in lakes, reservoirs, estuaries and rivers is widespread all over the world and the severity is increasing, especially in the developing countries like China. The assessment of water eutrophication has been advanced from simple individual parameters like total phosphorus, total nitrogen, etc., to comprehensive indexes like total nutrient status index. The major influencing factors on water eutrophication include nutrient enrichment, hydrodynamics, environmental factors such as temperature, salinity, carbon dioxide, element balance, etc., and microbial and biodiversity. The occurrence of water eutrophication is actually a complex function of all the possible influencing factors. The mechanisms of algal blooming are not fully understood and need to be further investigated.

  4. The role of phosphorus in eutrophication

    OpenAIRE

    Bogdanović Darinka M.

    2006-01-01

    Eutrophication is an increase in the biological productivity of water basins resulting from the accumulation of biogenic elements under the influence of anthropogenic factors. Natural eutrophication is a slow and inevitable process. Artifical eutrophica-tion is caused by human activity and it can be very rapid, especially in technologically developed countries. Eutrophication does not represent a mere change of water but a change in the metabolism of the entire ecosystem and hence a change of...

  5. Ecosystem-based management of coastal eutrophication

    DEFF Research Database (Denmark)

    Andersen, Jesper H.

    This thesis focuses on Ecosystem-Based Management (EBM) of coastal eutrophication. Special attention is put on connections between science and decision-making in regard to development, implementation and revision of evidence-based nutrient management strategies. Two strategies are presented...... and analysed: the Danish Action Plans on the Aquatic Environment and the eutrophication segment of the Baltic Sea Action Plan. Similarities and differences are discussed and elements required for making nutrient management strategies successful are suggested. Key words: Eutrophication, marine, Danish...

  6. Remote sensing and lake eutrophication

    Science.gov (United States)

    Wrigley, R. C.; Horne, A. J.

    1974-01-01

    An infrared photograph of part of Clear Lake, Cal., shows complex patterns of blue-green algal blooms which were not observed by conventional limnological techniques. Repeated observations of patterns such as these can be used to chart the surface movement of these buoyant algae and can also be used to help control algal scums in eutrophic lakes. Although it is believed that most of the observed patterns resulted from Aphanizomenon (a few were also observed which resulted from suspended sediment), spectral signatures of the algal patterns varied.

  7. Confidence rating of marine eutrophication assessments

    DEFF Research Database (Denmark)

    Murray, Ciarán; Andersen, Jesper Harbo; Kaartokallio, Hermanni

    2011-01-01

    This report presents the development of a methodology for assessing confidence in eutrophication status classifications. The method can be considered as a secondary assessment, supporting the primary assessment of eutrophication status. The confidence assessment is based on a transparent scoring ...... of the marine environment....

  8. The role of shellfish aquaculture in reduction of eutrophication in an urban estuary

    DEFF Research Database (Denmark)

    Bricker, Suzanne B.; Ferreira, Joao Gomes; Zhu, Changbo

    2017-01-01

    Mitigating coastal eutrophication is a global challenge. In many places where land-based management has reduced nutrient discharges, coastal waterbodies remain impaired. This study examined ‘bioextraction’ of nutrients from the water by oyster aquaculture in Long Island Sound, Connecticut......, as an example of how aquaculture might complement land-based measures in urban estuaries. Eutrophication status, nutrient removal, and ecosystem service value were estimated through eutrophication assessment, application of hydrologic, circulation, and local- and ecosystem-scale models, and economic valuation...

  9. Examining uncertainties in the linkage between global climate change and potential human health impacts in the western USA -- Hexachlorobenzene (HCB) as a case study

    Energy Technology Data Exchange (ETDEWEB)

    McKone, T.E.; Daniels, J.I. [Lawrence Livermore National Lab., CA (United States); Goldman, M. [Univ. of California, Davis, CA (United States)

    1994-09-30

    Industrial societies have altered the earth`s environment in ways that could have important, long-term ecological, economic, and health implications. In this paper the authors define, characterize, and evaluate parameter and outcome uncertainties using a model that links global climate change with predictions of chemical exposure and human health risk in the western region of the US. They illustrate the impact of uncertainty about global climate change on such potential secondary outcomes using as a case study the public health consequences related to the behavior environmentally of hexachlorobenzene (HCB), an ubiquitous multimedia pollutant. They begin by constructing a matrix that reveals the linkage between global environmental change and potential regional human-health effects that might be induced directly and/or indirectly by HCB released into the air and water. This matrix is useful for translating critical uncertainties into terms that can be understood and used by policy makers to formulate strategies against potential adverse irreversible health and economic consequences. Specifically, the authors employ a combined uncertainty/sensitivity analysis to investigate how the HCB that has been released is affected by increasing atmospheric temperature and the accompanying climate alterations that are anticipated and how such uncertainty propagates to affect the expected magnitude and calculational precision of estimates of associated potential human exposures and health effects.

  10. The role of phosphorus in eutrophication

    Directory of Open Access Journals (Sweden)

    Bogdanović Darinka M.

    2006-01-01

    Full Text Available Eutrophication is an increase in the biological productivity of water basins resulting from the accumulation of biogenic elements under the influence of anthropogenic factors. Natural eutrophication is a slow and inevitable process. Artifical eutrophica-tion is caused by human activity and it can be very rapid, especially in technologically developed countries. Eutrophication does not represent a mere change of water but a change in the metabolism of the entire ecosystem and hence a change of the ecosystem itself. In Serbia and Montenegro, all factors are present that promote eutrophication in both still (especially in lowland areas and running waters. This paper deals with the results of eutrophication monitoring and prognostication for the DTD canal network and major rivers and lakes in Serbia, including a special review of the trophic status of lakes in the country's main lowland region, the Vojvodina Province. As phosphorus concentration is an important factor in the process of eutrophication of a body of water, the study has devoted particular attention to the control of this element.

  11. VT Wildlife Linkage Habitat

    Data.gov (United States)

    Vermont Center for Geographic Information — (Link to Metadata) The Wildlife Linkage Habitat Analysis uses landscape scale data to identify or predict the location of potentially significant wildlife linkage...

  12. The role of benthic macrophytes and their associated macroinvertebrate community in coastal lagoon resistance to eutrophication.

    Science.gov (United States)

    Lloret, Javier; Marín, Arnaldo

    2009-12-01

    Eutrophication is widely recognised as one of the major menaces to coastal environments, particularly enclosed bays and lagoons. Although there is a general understanding of the consequences of eutrophication in these systems, there is a lack of sufficient knowledge concerning biotic feedbacks that influence eutrophication patterns and the resistance capacity of coastal environments. In this paper, the isotope ratios of main producers and consumers of a Mediterranean lagoon were examined in order to elucidate the fate of anthropogenic inputs from the main watercourse flowing into the lagoon. The results of the study of stable isotope data in the Mar Menor lagoon reflected that the whole benthic community plays an important role as a natural 'filter' that removes excess nutrients from the water column and stores them in the sediments, thereby enhancing lagoon resistance to eutrophication.

  13. An exploratory study to examine intentions to adopt an evidence-based HIV linkage-to-care intervention among state health department AIDS directors in the United States

    Directory of Open Access Journals (Sweden)

    Norton Wynne E

    2012-04-01

    Full Text Available Abstract Background Widespread dissemination and implementation of evidence-based human immunodeficiency virus (HIV linkage-to-care (LTC interventions is essential for improving HIV-positive patients' health outcomes and reducing transmission to uninfected others. To date, however, little work has focused on identifying factors associated with intentions to adopt LTC interventions among policy makers, including city, state, and territory health department AIDS directors who play a critical role in deciding whether an intervention is endorsed, distributed, and/or funded throughout their region. Methods Between December 2010 and February 2011, we administered an online questionnaire with state, territory, and city health department AIDS directors throughout the United States to identify factors associated with intentions to adopt an LTC intervention. Guided by pertinent theoretical frameworks, including the Diffusion of Innovations and the "push-pull" capacity model, we assessed participants' attitudes towards the intervention, perceived organizational and contextual demand and support for the intervention, likelihood of adoption given endorsement from stakeholder groups (e.g., academic researchers, federal agencies, activist organizations, and likelihood of enabling future dissemination efforts by recommending the intervention to other health departments and community-based organizations. Results Forty-four participants (67% of the eligible sample completed the online questionnaire. Approximately one-third (34.9% reported that they intended to adopt the LTC intervention for use in their city, state, or territory in the future. Consistent with prior, related work, these participants were classified as LTC intervention "adopters" and were compared to "nonadopters" for data analysis. Overall, adopters reported more positive attitudes and greater perceived demand and support for the intervention than did nonadopters. Further, participants varied with

  14. Ignoring dependency between linking variables and its impact on the outcome of probabilistic record linkage studies

    NARCIS (Netherlands)

    Tromp, Miranda; Meray, Nora; Ravelli, Anita C. J.; Reitsma, Johannes B.; Bonsel, Gouke J.

    2008-01-01

    Objectives: This study sought to examine the differences between ignoring (naive) and incorporating dependency (nonnaive) among linkage variables on the outcome of a probabilistic record linkage study. Design and Measurements: We used the outcomes of a previously developed probabilistic linkage

  15. Genetic linkage studies.

    Science.gov (United States)

    Dawn Teare, M; Barrett, Jennifer H

    Linkage analysis is used to map genetic loci by use of observations of related individuals. We provide an introduction to methods commonly used to map loci that predispose to disease. Linkage analysis methods can be applied to both major gene disorders (parametric linkage) and complex diseases (model-free or non-parametric linkage). Evidence for linkage is most commonly expressed as a logarithm of the odds score. We provide a framework for interpretation of these scores and discuss the role of simulation in assessment of statistical significance and estimation of power. Genetic and phenotypic heterogeneity can also affect the success of a study, and several methods exist to address such problems.

  16. BRIDGES: Evolution of basic and applied linkages in benthic science

    Science.gov (United States)

    Aumen, Nicholas G.; Gurtz, Martin E.; Barbour, Michael T.; Moerke, Ashley

    2010-01-01

    Growing awareness of environmental degradation resulted in stricter environmental regulations and laws for aquatic ecosystems. These regulations were followed by an increase in applied research and monitoring beginning in the early 1970s. The number of applied scientists who were members of the North American Benthological Society grew at a commensurate rate. The editors of J-NABS recognized that, despite these increases, submitted manuscripts mostly addressed basic science. In response, the BRIDGES section of J-NABS was created in 1994 to provide a forum for linking basic ecological principles to applied science problems and issues. We examined the emergence of applied science topics in J-NABS and its predecessor, Freshwater Invertebrate Biology, from their beginning in 1982 to 2009. We classified papers among 11 categories that included a basic/applied science linkage. In the 1980s, applied papers were predominantly on effects of eutrophication/pollution and landuse changes. When BRIDGES was established in 1994, papers were solicited by editors and BRIDGES sections usually included >1 paper on a common theme to express complementary or alternate viewpoints. Forty-two papers appeared in BRIDGES between 1994 and 2009, but the number per issue declined after 2001. The total number of applied science papers in J-NABS has increased since ∼1994. Citation analysis of BRIDGES papers illustrates how information is being cited, but applied papers often are used in ways that might not lead to citations. BRIDGES transitioned to a new format in September 2009 to address new types of complex, multifaceted linkages. All new BRIDGES articles will be open access, and authors will be encouraged to produce lay-language fact sheets and to post them on the web.

  17. A Water–Energy–Food Nexus Perspective on the Challenge of Eutrophication

    Directory of Open Access Journals (Sweden)

    V. Ratna Reddy

    2018-01-01

    Full Text Available This paper attempts to understand and explore the problem of eutrophication in the context of agriculture with the help of a nexus perspective. Eutrophication is significantly linked to water and energy resources with theoretically well-defined trade-offs and threshold levels. While looking at the linkages between water and land resources comprehensively, our paper questions the present approach to designing and implementing watershed management, and analyses the effects of agricultural intensification, especially in dry regions. Eutrophication is the process by which excessive nutrient loads in water bodies lead to undesirable water-quality problems and the degradation of the overall aquatic ecosystem. Due to limited information and knowledge on water and soil quality in most countries, farmers continue to use fertilizers at an increasing rate and agricultural run-off has been carrying ever more nitrogen and phosphorus into water bodies. This is likely to become a vicious cycle of eutrophication affecting food and water security. Of late, soil- and water-conservation interventions, like watershed development, are further reducing run-off. It is argued that there is a need to rethink the assumptions under which watershed interventions are designed and implemented.

  18. Subsidiary Linkage Patterns

    DEFF Research Database (Denmark)

    Andersson, Ulf; Perri, Alessandra; Nell, Phillip C.

    2012-01-01

    This paper investigates the pattern of subsidiaries' local vertical linkages under varying levels of competition and subsidiary capabilities. Contrary to most previous literature, we explicitly account for the double role of such linkages as conduits of learning prospects as well as potential cha...... in strongly competitive environments tend to shy away from high quality linkages. We discuss our findings in light of the literature on spillovers and inter-organizational linkages.......This paper investigates the pattern of subsidiaries' local vertical linkages under varying levels of competition and subsidiary capabilities. Contrary to most previous literature, we explicitly account for the double role of such linkages as conduits of learning prospects as well as potential...... channels for spillovers to competitors. We find a curvilinear relationship between the extent of competitive pressure and the quality of a subsidiary's set of local linkages. Furthermore, the extent to which a subsidiary possesses capabilities moderates this relationship: Very capable subsidiaries...

  19. Use of Coupled Eutrophication and Network Models for Examination of Fisheries and Eutrophication Processes

    Science.gov (United States)

    2008-03-01

    available portion of an algal group, for example, is determined: ( )BAxz Max Bx CTz = − PAsz UDsz DOCAsz UBxsz BAxsz ULsz LPOCAsz URsz RPOCAsz...7) in which: BAxz = portion of algal group x available to zooplankton group z (g C m–3) CTz = threshold concentration below which

  20. Eutrophication of freshwater and marine ecosystems

    Science.gov (United States)

    Smith, Val H.; Joye, Samantha B.; Howarth, Robert W.

    2006-01-01

    Initial understanding of the links between nutrients and aquatic productivity originated in Europe in the early 1900s, and our knowledge base has expanded greatly during the past 40 yr. This explosion of eutrophication-related research has made it unequivocally clear that a comprehensive strategy to prevent excessive amounts of nitrogen and phosphorus from entering our waterways is needed to protect our lakes, rivers, and coasts from water quality deterioration. However, despite these very significant advances, cultural eutrophication remains one of the foremost problems for protecting our valuable surface water resources. The papers in this special issue provide a valuable cross section and synthesis of our current understanding of both freshwater and marine eutrophication science. They also serve to identify gaps in our knowledge and will help to guide future research.

  1. [Ecological engineering for eutrophication control in lake].

    Science.gov (United States)

    Sun, G; Sheng, L

    2001-08-01

    An ecological engineering was conducted for eutrophication control in the Nanhu Lake of Changchun. In 1996, the removal of phosphorus by harvesting aquatic macrophytes and fishes was 149.6 kg and 189.9 kg, respectively, and the phosphorus fixed in molluscs was 153.4 kg. The total output was 492.9 kg, which amounted approximately to the annual phosphorus input to the lake. After ecological engineering, the water quality turned better, the TP concentration in lake water decreased, the phytoplankton density reduced, and the number of phytoplankton species increased. The roles of molluscs and fish in controlling lake eutrophication should be further studied. Ecological engineering is an ideal method to control the eutrophication of urban lakes.

  2. Aspects of record linkage

    NARCIS (Netherlands)

    Schraagen, Marijn Paul

    2014-01-01

    This thesis is an exploration of the subject of historical record linkage. The general goal of historical record linkage is to discover relations between historical entities in a database, for any specific definition of relation, entity and database. Although this task originates from historical

  3. Drainage basin nutrient inputs and eutrophication: an integrated approach

    OpenAIRE

    Wassmann, Paul; Olli, Kalle

    2005-01-01

    Eutrophication is an increase in primary production due to increased nutrient supply and its consequences. In its widest sense eutrophication means any increase of nutrient availability that increases primary production. Frequently, however, eutrophication is understood exclusively as the consequence of nutrient input by anthropogenic activities. The primary consequence of eutrophication in aquatic environments is an enhancement of algal productivity and accumulation of algal biomass. Seco...

  4. Viral ecology of a shallow eutrophic lake

    NARCIS (Netherlands)

    Tijdens, M.

    2007-01-01

    This thesis aims to give an insight into the ecology of the viral community in a shallow eutrophic lake. To achieve this, the population dynamics, diversity and control of the viral community in Lake Loosdrecht were studied, as well as the impact of the viral community on plankton mortality and

  5. Algae, phytoplankton and eutrophication research and management ...

    African Journals Online (AJOL)

    A brief history of South African research on and management of algae-, phytoplankton- and eutrophication-related problems is presented, including their ecological, social and economic impacts, which provides a basis for formulation of future research needs. The contributions of southern African research on different ...

  6. Subsidiary Linkage Patterns

    DEFF Research Database (Denmark)

    Perri, Alessandra; Andersson, Ulf; Nell, Phillip C.

    of competition and subsidiary capabilities. Our theoretical development and the results from the analysis document a far more complex and dynamic relationship between levels of competition and MNCs’ local participation in knowledge intensive activities, i.e. learning and spillovers, than previous studies do. We......This paper investigates local vertical linkages of foreign subsidiaries and the dual role of such linkages as conduits for learning as well as potential channels for spillovers to competitors. On the basis of data from 97 subsidiaries, we analyze the quality of such linkages under varying levels...... find a curvilinear relationship between the extent of competitive pressure and the quality of local linkages confirming our argument of a trade-off between learning prospects and spillover risks. Furthermore, the level of subsidiary capabilities moderates this relationship....

  7. Eutrophication downstream from small reservoirs in mountain rivers of Central Spain.

    Science.gov (United States)

    Camargo, Julio A; Alonso, Alvaro; de la Puente, Marcos

    2005-09-01

    In this research we examined the hypothesis that upper reaches of rivers and streams can experience eutrophication as a consequence of deep releases from dams. Field studies were conducted in four mountain rivers (Tormes, Riaza, Eresma and Miraflores Rivers) of Central Spain. The watersheds of these rivers are underlain by siliceous rocks. A small deep-release storage reservoir is found in the upper reaches of each river. Two sampling sites, upstream and downstream from the reservoir, were established in stony riffles of each impounded river. Significant (P rivers, can act as nutrient sources, causing eutrophication downstream. Nutrients would ultimately come from land/forest runoff. The fact that terrestrial vegetation was not completely removed before filling reservoirs could also contribute to the eutrophication process.

  8. Contribution of Cultural Eutrophication to Marsh Loss in Jamaica Bay (NY)

    Science.gov (United States)

    Loss of salt marsh area in the Jamaica Bay Estuary (NY) has accelerated in recent years, with loss rates as high as 45 acres per year. A contributing factor to this acceleration is likely cultural eutrophication due to over 6 decades of sewage effluent inputs. We examined marsh...

  9. Impact of drain water on water quality and eutrophication status of ...

    African Journals Online (AJOL)

    The ecological and biological status of Lake Burullus was examined in 2006 to determine its water quality and eutrophication status in response to the quality and quantity of drain water entering it. The lake suffers from excessive nutrient concentrations. Chlorophyll a showed wide variations over the sampling period with ...

  10. The role of shellfish aquaculture in reduction of eutrophication in an urban estuary

    DEFF Research Database (Denmark)

    Bricker, Suzanne B.; Ferreira, Joao Gomes; Zhu, Changbo

    2018-01-01

    Mitigating coastal eutrophication is a global challenge. In many places where land-based management has reduced nutrient discharges, coastal waterbodies remain impaired. This study examined ‘bioextraction’ of nutrients from the water by oyster aquaculture in Long Island Sound, Connecticut, as an ...

  11. Networks, linkages, and migration systems.

    Science.gov (United States)

    Fawcett, J T

    1989-01-01

    Recent theoretical interest in migration systems calls attention to the functions of diverse linkages between countries in stimulating, directing,and maintaining international flows of people. This article proposes a conceptual framework for the non-people linkages in international migration systems and discusses the implications for population movement of the 4 categories and 3 types of linkages that define the network. The 4 categories include 1) state to state relations, 2) mass culture connections, 3) family and personal networks, and 4) migrant agency activities. The 3 types of linkages are 1) tangible linkages, 2) regulatory linkages, and 3) relational linkages.

  12. Effect of eutrophication on the distribution of arsenic species in eutrophic and mesotrophic lakes.

    Science.gov (United States)

    Hasegawa, H; Rahman, M Azizur; Matsuda, T; Kitahara, T; Maki, T; Ueda, K

    2009-02-01

    Effects of eutrophication on arsenic speciation were studied in eutrophic Lake Kiba and mesotrophic Lake Biwa, Japan. By combining hydride generation atomic absorption spectrometry with ultraviolet irradiation, inorganic, methyl and ultraviolet-labile fractions of arsenic were determined. In both Lakes, inorganic species (As(V+III)) dominated over other forms of arsenic all the year round. Most of methylarsenic fraction was dimethylarsinic acid (DMAA), and the concentration of monomethylarsonic acid (MMAA) was below the detection limit. Measurements of size-fractioned arsenic concentrations in water column indicate that most of the DMAA was distributed in truly dissolved fraction (0.45 microm) and colloidal (10 kDa-0.45 microm) fractions. Arsenic speciation in eutrophic Lake Kiba fluctuated greatly with season. The ultraviolet-labile fractions were observed with the increase of DMAA from May to October, and they disappeared with the decrease of DMAA in January. In mesotrophic Lake Biwa, the ultraviolet-labile fractions of arsenic were not influenced as much as those in eutrophic Lake Kiba. On the other hand DMAA concentration was higher in Lake Biwa compared to that in Lake Kiba. The results suggest that the biosynthesis of complex organoarsenicals was enhanced by eutrophication, and the arsenic speciation would be influenced by the balance of biological processes in natural waters.

  13. Effect of eutrophication on the distribution of arsenic species in eutrophic and mesotrophic lakes

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, H. [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192 (Japan)], E-mail: hhiroshi@t.kanazawa-u.ac.jp; Rahman, M. Azizur; Matsuda, T.; Kitahara, T.; Maki, T.; Ueda, K. [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192 (Japan)

    2009-02-01

    Effects of eutrophication on arsenic speciation were studied in eutrophic Lake Kiba and mesotrophic Lake Biwa, Japan. By combining hydride generation atomic absorption spectrometry with ultraviolet irradiation, inorganic, methyl and ultraviolet-labile fractions of arsenic were determined. In both Lakes, inorganic species (As(V + III)) dominated over other forms of arsenic all the year round. Most of methylarsenic fraction was dimethylarsinic acid (DMAA), and the concentration of monomethylarsonic acid (MMAA) was below the detection limit. Measurements of size-fractioned arsenic concentrations in water column indicate that most of the DMAA was distributed in truly dissolved fraction (< 10 kDa), while ultraviolet-labile fractions were distributed in particulate (> 0.45 {mu}m) and colloidal (10 kDa-0.45 {mu}m) fractions. Arsenic speciation in eutrophic Lake Kiba fluctuated greatly with season. The ultraviolet-labile fractions were observed with the increase of DMAA from May to October, and they disappeared with the decrease of DMAA in January. In mesotrophic Lake Biwa, the ultraviolet-labile fractions of arsenic were not influenced as much as those in eutrophic Lake Kiba. On the other hand DMAA concentration was higher in Lake Biwa compared to that in Lake Kiba. The results suggest that the biosynthesis of complex organoarsenicals was enhanced by eutrophication, and the arsenic speciation would be influenced by the balance of biological processes in natural waters.

  14. Carbon fluxes in an eutrophic urban lake

    Science.gov (United States)

    Barros, Nathan; Mendonça, Raquel; Huszar, Vera; Roland, Fábio; Kosten, Sarian

    2014-05-01

    Eutrophic lakes have a still unknown net effect on greenhouse gas emission. On one hand, the high photosynthetic rates enhance the freshwater carbon dioxide (CO2) sink. On the other hand, the intense organic matter decomposition may lead to high CO2 release and, when the sediment becomes anoxic, also to more methane (CH4) production. Here, we measured CO2 and CH4 emissions from a highly eutrophic urban lake monthly during summer, autumn and winter, over 24 hour periods. The lake was predominantly a net carbon source to the atmosphere. On the few periods when the lake was a CO2 sink, the magnitude of CO2 influx to the water was small. The CO2 diffusive emission at night was higher than during the day due to daytime CO2 uptake by photosynthesis. The same pattern was not found for CH4 diffusive emission, which was high both during the day and night even though CH4 oxidation reduced the CH4 emission in almost 50%. CH4 emission through bubbles was proven highly dependent on temperature and no bubbles were emitted during colder months. In our study lake, CO2 and CH4 production through mineralization in the water column and in the sediment should be offsetting CO2 fixation by primary production. The greenhouse emission from this system can be even higher considering CO2-equivalents. As conclusion, our data confront the usually accepted idea that eutrophic lakes are carbon sinks.

  15. Morphological and biomechanical response to eutrophication and hydrodynamic stresses.

    Science.gov (United States)

    Zhu, Guorong; Yuan, Changbo; Di, Guilan; Zhang, Meng; Ni, Leyi; Cao, Te; Fang, Rongting; Wu, Gongguo

    2017-12-05

    Eutrophication and hydrodynamics determine the final distribution patterns of aquatic macrophytes; however, there is limited available knowledge regarding their interactive effects. Morphological and biomechanical responses to eutrophication and hydrodynamic stresses were assessed by sampling five abundant and dominant species, Potamogeton maackianus, P. pectinatus, P. lucens, Ceratophyllum demersum and Myriophyllum spicatum, in three macrophyte beds in Lake Erhai, Yunnan Province, China: one exposed to eutrophication and moderate southeast (SE) wind; one with mesotrophication, but sheltered by the lakeshore, with weak wind disturbance; and one with meso-eutrophication and strong SE wind. The results showed significant interactive effects of eutrophication and hydrodynamics on most biomechanical traits and some morphological traits, suggesting that aquatic macrophytes preferentially undergo biomechanical adjustments to resist the coexisting eutrophication and hydrodynamic stresses. In particular, hydrodynamics increased both the tensile force and tensile strain of P. maackianus under meso-eutrophication and dramatically decreased them in eutrophic areas, suggesting that eutrophication triggers mechanical failure in this species. Additionally, P. pectinatus, C. demersum and M. spicatum showed the lowest and highest values for the biomechanical variables (greater values for M. spicatum) in the most eutrophic and hydrodynamic areas, respectively, implying that increases in hydrodynamics primarily induce mechanical damage in eutrophic species. The plants generally exhibited greater tensile strain in both shallow and deep waters and the greatest tensile force at moderate depths. The stem cross-sectional area, plant height, stem length, internode length, and branch traits were all responsible for determining the biomechanical variables. This study reveals that hydrodynamic changes primarily induce mechanical damage in eutrophic species, whereas eutrophication triggers

  16. Freshwater diatoms as environmental indicators: evaluating the effects of eutrophication using species morphology and biological indices.

    Science.gov (United States)

    Vilmi, Annika; Karjalainen, Satu Maaria; Landeiro, Victor L; Heino, Jani

    2015-05-01

    Anthropogenic eutrophication is a major form of perturbation in freshwaters, and several approaches aim to recognise its effects on lake ecosystems. We compared the responses of diatom species morphology, diversity indices and diatom indices to total phosphorus, total nitrogen and distance from a point stressor causing eutrophication in a large lake. We specifically examined the degree to which extent nutrients and distance to the stressor affect variation in the values of various biological indices and diatom valve size. In addition, special attention was given to the adequate repetition of diatom valve width measurements in the context of environmental assessment. Our results showed that diatom valve width was a better indicator of nutrient concentrations than any of the diatom and diversity indices examined. However, the results varied between the two study transects, suggesting that the diatom-based variables not only respond to nutrients but also to other environmental factors (e.g. shoreline morphology). We also found that when using the method based on diatom morphology, one should measure more valves than has been originally suggested to provide a more reliable picture of response to eutrophication. We argue that diatom morphology could be considered as an additional environmental assessment tool, because it may complement the information provided by the traditional diatom indices. Diatom valve width may also be more sensitive to early phases of the eutrophication process and its effects on freshwater ecosystems than various diatom indices that were developed in regional contexts with wide ranges in nutrient levels.

  17. Data linkage algebra, data linkage dynamics, and priority rewriting

    NARCIS (Netherlands)

    Bergstra, J.A.; Middelburg, C.A.

    2008-01-01

    We introduce an algebra of data linkages. Data linkages are intended for modelling the states of computations in which dynamic data structures are involved. We present a simple model of computation in which states of computations are modelled as data linkages and state changes take place by means of

  18. Data Linkage Algebra, Data Linkage Dynamics, and Priority Rewriting

    NARCIS (Netherlands)

    Bergstra, J.; Middelburg, C.A.

    2013-01-01

    We introduce an algebra of data linkages. Data linkages are intended for modelling the states of computations in which dynamic data structures are involved. We present a simple model of computation in which states of computations are modelled as data linkages and state changes take place by means of

  19. Eutrophication, Nile perch and food-web interactions in south-east Lake Victoria

    NARCIS (Netherlands)

    Cornelissen, I.J.M.

    2015-01-01

    The increasing eutrophication, the introduction of Nile perch (Lates niloticus) and the increasing fishing pressure has changed Lake Victoria tremendously the last century. Since the 1960s, eutrophication increased primary production, enabling an increase in fish production. However, eutrophication

  20. Marine Litter, Eutrophication and Noise Assessment Tools

    Science.gov (United States)

    Palazov, Atanas; Velcheva, Maya; Milkova, Tanya; Slabakova, Violeta; Marinova, Veselka

    2017-04-01

    MARLEN - Marine Litter, Eutrophication and Noise Assessment Tools is a project under the Programme BG02.03: Increased capacity for assessing and predicting environmental status in marine and inland waters, managed by Bulgarian Ministry of environment and waters and co-financed by the Financial Mechanism of the European Economic Area (EEA FM) 2009 - 2014. Project Beneficiary is the Institute of oceanology - Bulgarian Academy of Sciences with two partners: Burgas municipality and Bulgarian Black Sea Basin Directorate. Initial assessment of ecological state of Bulgarian marine waters showed lack of data for some descriptors of MSFD. The main goal of MARLEN is to build up tools for assessment of marine environment by implementing new technologies and best practices for addressing three main areas of interest with lack of marine data in particular: a) Marine litter detection and classification in coastal areas; b) Regular near real time surface water eutrophication monitoring on large aquatory; c) Underwater noise monitoring. Developed tools are an important source of real time, near real time and delay mode marine data for Bulgarian Black Sea waters. The partnership within the project increased capacity for environmental assessments and training of personnel and enhances collaboration between scientific institutes, regional and local authorities. Project results supported implementation of MSFD in Bulgarian marine waters for the benefit of coastal population, marine industry, tourism, marine research and marine spatial planning.

  1. Agriculture–Tourism Linkages in Botswana: Evidence from the ...

    African Journals Online (AJOL)

    This article examines the linkages between the tourism and agriculture sectors in Botswana using evidence gathered from the country's growing safari lodge accommodation sector. The findings reveal limited local linkages between agriculture and tourism, and instead the existence of high levels of food imports from ...

  2. JamesWattandhisLinkages

    Indian Academy of Sciences (India)

    Admin

    say by half, as shown in Figu e 5b but it would reduce the motion of F thus restricting the stroke length of the piston. (a) igure 5. (a) Watt's linkage with one body acting as the great beam. (b) An attempt to reduce the size, which reduces the stroke length of the piston. ... It has two gears that mesh with each other. One gear is ...

  3. Wargaming Strategic Linkage

    Science.gov (United States)

    2009-01-01

    Wargaming Strategic Linkage Peter P. Perla • Michael C. Markowitz CRM D0019256.A2/Final January 2009 20090219290 CNA ANALYSIS & SOLUTIONS...players’ hands with predict - able player discontent and argument. The broader pathology stems from player "paranoia" that Control is simply...Demonstration, FOUO, Dec 2000 (CNA Research Memorandum D0003043.A1/Final Peter P. Perla, Andrew Ilachinski, Carol M. Hawk , Michael C. Markow- itz

  4. Producer Services, Manufacturing Linkages, and Trade

    NARCIS (Netherlands)

    J.F. François (Joseph); J. Kepler; J. Woerz

    2007-01-01

    textabstractWorking with a mix of panel data on goods and services trade for the OECD for 1994-2004, combined with social accounts data (i.e. data on intermediate linkages) for 78 countries benchmarked to the panel midpoint, we examine the role of services as inputs in manufacturing, with a

  5. Linkage of health and aged care service events: comparing linkage and event selection methods

    Directory of Open Access Journals (Sweden)

    Rosman Diana

    2008-07-01

    Full Text Available Abstract Background Data linkage is a technique that has long been used to connect information across several disparate data sources – most commonly for medical and population health research. Often the purpose is to connect data for individuals over extended time periods or across different service settings, and so person-based linkage using detailed personal information is preferred. Linkage which aims to link connected events, on the other hand, requires information about the time and place of the event as well as the person or persons involved in that event in order to make high quality linkages. This paper describes the detailed process of event linkage and compares directly an event-based linkage method for identifying transition events between two care sectors in Australia with a well-established high quality longitudinal person-based linkage which facilitates identification of event data for individuals. Methods Direct comparisons are made between transition events identified using an event-based linkage and an existing person-based linkage for people moving from hospital into aged care in Western Australia. Several aspects of event-based linkage are examined: refinement of the strategy to reduce false positives, causes of false positives and false negatives, quality of the linked event dataset, and utility of the linked event dataset for transition analysis. Results Over 97% of the event-based links were among those selected using the person-based linkage and over 90% of the latter were identified by the event-based method, with the remainder missed mostly due to differences in reported event date or residential region. Consequently the two linked datasets were sufficiently similar to give very similar results for analyses, but the actual volume of movement from hospital to RAC was underestimated by about 10% by the event-based method. Conclusion This project has allowed a 'preferred event' event-based linkage strategy to be selected

  6. Eutrophication of lake waters in China: cost, causes, and control.

    Science.gov (United States)

    Le, C; Zha, Y; Li, Y; Sun, D; Lu, H; Yin, B

    2010-04-01

    Lake water eutrophication has become one of the most important factors impeding sustainable economic development in China. Knowledge of the current status of lake water eutrophication and determination of its mechanism are prerequisites to devising a sound solution to the problem. Based on reviewing the literature, this paper elaborates on the evolutional process and current state of shallow inland lake water eutrophication in China. The mechanism of lake water eutrophication is explored from nutrient sources. In light of the identified mechanism strategies are proposed to control and tackle lake water eutrophication. This review reveals that water eutrophication in most lakes was initiated in the 1980s when the national economy underwent rapid development. At present, the problem of water eutrophication is still serious, with frequent occurrence of damaging algal blooms, which have disrupted the normal supply of drinking water in shore cities. Each destructive bloom caused a direct economic loss valued at billions of yuan. Nonpoint pollution sources, namely, waste discharge from agricultural fields and nutrients released from floor deposits, are identified as the two major sources of nitrogen and phosphorus. Therefore, all control and rehabilitation measures of lake water eutrophication should target these nutrient sources. Biological measures are recommended to rehabilitate eutrophied lake waters and restore the lake ecosystem in order to bring the problem under control.

  7. Improving the accuracy of estimation of eutrophication state index ...

    African Journals Online (AJOL)

    Trophic Level Index (TLI) is oen used to assess the general eutrophication state of inland lakes in water science, technology, and engineering. In this paper, a data-driven inland-lake eutrophication assessment method was proposed by using an articial neural network (ANN) to build relationships from remote sensing data ...

  8. Eutrophication: Present reality and future challenges for South Africa ...

    African Journals Online (AJOL)

    Eutrophication-management options include reduction of phosphorus in detergents, biomanipulation of the food web, accurate prediction of cyanobacterial growth cycles, and mechanical disturbance of the epilimnion. The implementation of adaptive management to deal with eutrophication would ensure the testing and ...

  9. Eutrophication: Present reality and future challenges for South Africa

    African Journals Online (AJOL)

    1980-08-01

    Aug 1, 1980 ... ensure the testing and application of the most appropriate methodology to each eutrophic water body. Continued .... Table 1. The classification system used by the Department Water Affairs to classify the National Eutrophication Monitoring .... of Water Affairs continued its support of this initiative by fund-.

  10. Linking climate change mitigation and coastal eutrophication management through biogas technology

    DEFF Research Database (Denmark)

    Kaspersen, Bjarke Stoltze; Christensen, Thomas Budde; Fredenslund, Anders Michael

    2016-01-01

    concept for anaerobic co-digestion of food industry residues, manure and beach-cast seaweed has been developed and tested in order to quantify the potential for synergies between climate change mitigation and coastal eutrophication management in the Køge Bay catchment. The biogas plant, currently under...... construction, was designed to handle an annual input of up to 200,000t of biomass based on four main fractions: pectin wastes, carrageenan wastes, manure and beach-cast seaweed. This paper describes how this bioenergy concept can contribute to strengthening the linkages between climate change mitigation...... strategies and Water Framework Directive (WFD) action planning. Our assessments of the projected biogas plant indicate an annual reduction of GHG emissions of approx. 40,000t CO2 equivalents, corresponding to approx. 1/3 of current total GHG emissions in the Municipality of Solrød. In addition, nitrogen...

  11. Eutrophication potential of Payette Lake, Idaho

    Science.gov (United States)

    Woods, Paul F.

    1997-01-01

    Payette Lake was studied during water years 1995-96 to determine the 20.5-square-kilometer lake's assimilative capacity for nutrients and, thus, its eutrophication potential. The study included quantification of hydrologic and nutrient budgets, characterization of water quality in the limnetic and littoral zones, development of an empirical nutrient load/lake response model, and estimation of the limnological effects of a large-scale forest fire in the lake's 373-square-kilometer watershed during the autumn of 1994. Streamflow from the North Fork Payette River, the lake's primary tributary, delivered about 73 percent of the lake's inflow over the 2 years. Outflow from the lake, measured since 1908, was 128 and 148 percent of the long-term average in 1995 and 1996, respectively. The larger volumes of outflow reduced the long-term average water-

  12. Differences in dietary pattern between obese and eutrophic children

    Directory of Open Access Journals (Sweden)

    Balthazar Emilia A

    2011-12-01

    Full Text Available Abstract Background Excessive consumption of energy is a decisive factor of obesity, but a simple quantitative assessment of consumption between obese and eutrophic individuals not always explains the problem, raising questions about the importance of the qualitative aspects of food. Therefore, the purpose of this study was to evaluate the differences in nutrient composition and meal patterns between eutrophic and obese schoolchildren. Methods The diet of 83 children (42 obese and 41 eutrophic, aged between 7 and 11 years of age, was assessed by two non-consecutive dietary recalls. After the software analysis of macro and micronutrients composition, the different types and amount of legumes, fruits and vegetables were analyzed to verify the dietary patterns. Results No differences were verified in energy consumption between the groups (eutrophic = 1934.2 ± 672.7 kcal, obese = 1835.8 ± 621.2 kcal. In general, children showed consumption within the recommended ranges of carbohydrates, lipids and proteins. The average consumption of fiber was higher in the eutrophic group (20.7 g when compared to the obese group (14.8 g. The dietary fiber was strongly correlated with the number of servings of beans (r = 0.77, when compared to fruits (r = 0.44 and leafy vegetables (r = 0.13. It was also observed that the higher the consumption of fiber and beans, the lower the proportion of dietary fat (r = -0.22 in the diet. Generally, there was a low consumption of fiber (20.7 g = eutrophic group/14.8 g = obese group, beans (1.1 portions in the eutrophic and obese groups, fruits (0.7 portions eutrophic group and 0.6 obese group and vegetables (1.3 eutrophic group and 1.1 obese group. Conclusions It is concluded that the obesity was more related to a dietary pattern of low intake of dietary fiber than excessive energy consumption and macronutrients imbalance.

  13. Design of special planar linkages

    CERN Document Server

    Zhao, Jing-Shan; Ma, Ning; Chu, Fulei

    2013-01-01

    Planar linkages play a very important role in mechanical engineering. As the simplest closed chain mechanisms, planar four-bar linkages are widely used in mechanical engineering, civil engineering and aerospace engineering.Design of Special Planar Linkages proposes a uniform design theory for planar four-bar linkages. The merit of the method proposed in this book is that it allows engineers to directly obtain accurate results when there are such solutions for the specified n precise positions; otherwise, the best approximate solutions will be found. This book discusses the kinematics and reach

  14. Paroxysmal kinesigenic dyskinesia and infantile convulsions - Clinical and linkage studies

    NARCIS (Netherlands)

    Swoboda, KJ; Soong, BW; McKenna, C; Brunt, ERP; Litt, M; Bale, JF; Ashizawa, T; Bennett, LB; Bowcock, AM; Roach, ES; Gerson, D; Matsuura, T; Heydemann, PT; Nespeca, MP; Jankovic, J; Leppert, M; Ptacek, LJ

    2001-01-01

    Objective: To clinically characterize affected individuals in families with paroxysmal kinesigenic dyskinesia (PEM), examine the association with infantile convulsions, and confirm linkage to a pericentromeric chromosome 16 locus. Background: PKD is characterized by frequent, recurrent attacks of

  15. Paroxysmal kinesigenic dyskinesia and infantile convulsions - Clinical and linkage studies

    NARCIS (Netherlands)

    Swoboda, KJ; Soong, BW; McKenna, C; Brunt, ERP; Litt, M; Bale, JF; Ashizawa, T; Bennett, LB; Bowcock, AM; Roach, ES; Gerson, D; Matsuura, T; Heydemann, PT; Nespeca, MP; Jankovic, J; Leppert, M; Ptacek, LJ

    2000-01-01

    Objective: To clinically characterize affected individuals in families with paroxysmal kinesigenic dyskinesia (PKD), examine the association with infantile convulsions, and confirm linkage to a pericentromeric chromosome 16 locus. Background PKD is characterized by frequent, recurrent attacks of

  16. Linkages between animal and human health sentinel data

    Directory of Open Access Journals (Sweden)

    Rabinowitz Peter

    2009-04-01

    order to examine researchers' decisions in linkage strategies between animal and human data.

  17. Integrated approaches to drainage basin nutrient inputs and coastal eutrophication: an introduction

    OpenAIRE

    Wassmann, Paul; Olli, Kalle

    2005-01-01

    Ingress Eutrophication is an increase in primary production due to increased nutrient supply and its consequences. In its widest sense eutrophication means any increase of nutrient availability that increases primary production. Frequently, however, eutrophication is understood exclusively as the consequence of nutrient input by anthropogenic activities. The primary consequence of eutrophication in aquatic environments is an enhancement of algal productivity and ...

  18. Eutrophication levels of some South African impoundments III. Roodeplaat Dam

    CSIR Research Space (South Africa)

    Steyn, DJ

    1976-01-01

    Full Text Available . The purpose of the study was to determine the present eutrophication status of Roodeplaat dam and the effect of either increased discharges of secondary treated sewage effluents....

  19. Eutrophication of aquatic ecosystems: Bistability and soil phosphorus

    Science.gov (United States)

    Carpenter, Stephen R.

    2005-01-01

    Eutrophication (the overenrichment of aquatic ecosystems with nutrients leading to algal blooms and anoxic events) is a persistent condition of surface waters and a widespread environmental problem. Some lakes have recovered after sources of nutrients were reduced. In others, recycling of phosphorus from sediments enriched by years of high nutrient inputs causes lakes to remain eutrophic even after external inputs of phosphorus are decreased. Slow flux of phosphorus from overfertilized soils may be even more important for maintaining eutrophication of lakes in agricultural regions. This type of eutrophication is not reversible unless there are substantial changes in soil management. Technologies for rapidly reducing phosphorus content of overenriched soils, or reducing erosion rates, are needed to improve water quality. PMID:15972805

  20. Observations on cyanobacterial population collapse in eutrophic lake water

    NARCIS (Netherlands)

    Gons, H.J.; Ebert, J.; Hoogveld, H.L.; Van den Hove, L.; Pel, R.; Takkenberg, W.; Woldringh, C.J.

    2002-01-01

    In two laboratory-scale enclosures of water from the shallow, eutrophic Lake Loosdrecht (the Netherlands), the predominating filamentous cyanobacteria grew vigorously for 2 weeks, but then their populations simultaneously collapsed, whereas coccoid cyanobacteria and algae persisted . The collapse

  1. Eutrophication of aquatic ecosystems: bistability and soil phosphorus.

    Science.gov (United States)

    Carpenter, Stephen R

    2005-07-19

    Eutrophication (the overenrichment of aquatic ecosystems with nutrients leading to algal blooms and anoxic events) is a persistent condition of surface waters and a widespread environmental problem. Some lakes have recovered after sources of nutrients were reduced. In others, recycling of phosphorus from sediments enriched by years of high nutrient inputs causes lakes to remain eutrophic even after external inputs of phosphorus are decreased. Slow flux of phosphorus from overfertilized soils may be even more important for maintaining eutrophication of lakes in agricultural regions. This type of eutrophication is not reversible unless there are substantial changes in soil management. Technologies for rapidly reducing phosphorus content of overenriched soils, or reducing erosion rates, are needed to improve water quality.

  2. Modeling of HABs and eutrophication: Status, advances, challenges

    NARCIS (Netherlands)

    Glibert, P.M.; Allen, J.I.; Bouwman, A.F.; Brown, C.W.; Flynn, K.J.; Lewitus, A.J.; Madden, C.J.

    2010-01-01

    Harmful algal blooms (HABs) are often associated with eutrophication of coastal waters and estuaries. However, identifying quantitative relationships between nutrient input and proliferation of specific algal species is very challenging and complex. The complexity arises from the diversity of

  3. Effect of combined ecological floating bed for eutrophic lake remediation

    Science.gov (United States)

    Zheng, Liguo; Wang, Haiping

    2017-05-01

    A novel combined ecological floating bed(CEFB) integrated high-density hydrophyte and aquatic animals, the wave-making equipments, water cycling automatic aerators and fluorescence inducing equipments. The water quality of a eutrophic lake was improved significantly after three months remediation of CEFB. Compared with the background value, the results showed that the removal efficiencies of total nitrogen (TN), ammonia(NH3-N), total phosphorous(TP) and chemical oxygen demand (COD) in the water reached 31.5%, 33%, 30.5% and 53%, respectively. CEFB could manipulate biotic interactions in the aquatic ecosystem, and then absorb eutrophic material efficiently by the co-effect of floating the sediment slowly, refreshing the static eutrophic water body, changing the photosynthetic and biochemical environment of the eutrophic water body and inducing plankton directional movement. At the same time, plants and fish grew good in CEFB,which can bring economic income to some extent.

  4. Biological process linkage networks.

    Directory of Open Access Journals (Sweden)

    Dikla Dotan-Cohen

    Full Text Available The traditional approach to studying complex biological networks is based on the identification of interactions between internal components of signaling or metabolic pathways. By comparison, little is known about interactions between higher order biological systems, such as biological pathways and processes. We propose a methodology for gleaning patterns of interactions between biological processes by analyzing protein-protein interactions, transcriptional co-expression and genetic interactions. At the heart of the methodology are the concept of Linked Processes and the resultant network of biological processes, the Process Linkage Network (PLN.We construct, catalogue, and analyze different types of PLNs derived from different data sources and different species. When applied to the Gene Ontology, many of the resulting links connect processes that are distant from each other in the hierarchy, even though the connection makes eminent sense biologically. Some others, however, carry an element of surprise and may reflect mechanisms that are unique to the organism under investigation. In this aspect our method complements the link structure between processes inherent in the Gene Ontology, which by its very nature is species-independent. As a practical application of the linkage of processes we demonstrate that it can be effectively used in protein function prediction, having the power to increase both the coverage and the accuracy of predictions, when carefully integrated into prediction methods.Our approach constitutes a promising new direction towards understanding the higher levels of organization of the cell as a system which should help current efforts to re-engineer ontologies and improve our ability to predict which proteins are involved in specific biological processes.

  5. Phosphorus mitigation to control river eutrophication: murky waters, inconvenient truths, and "postnormal" science.

    Science.gov (United States)

    Jarvie, Helen P; Sharpley, Andrew N; Withers, Paul J A; Scott, J Thad; Haggard, Brian E; Neal, Colin

    2013-01-01

    This commentary examines an "inconvenient truth" that phosphorus (P)-based nutrient mitigation, long regarded as the key tool in eutrophication management, in many cases has not yet yielded the desired reductions in water quality and nuisance algal growth in rivers and their associated downstream ecosystems. We examine why the water quality and aquatic ecology have not recovered, in some case after two decades or more of reduced P inputs, including (i) legacies of past land-use management, (ii) decoupling of algal growth responses to river P loading in eutrophically impaired rivers; and (iii) recovery trajectories, which may be nonlinear and characterized by thresholds and alternative stable states. It is possible that baselines have shifted and that some disturbed river environments may never return to predisturbance conditions or may require P reductions below those that originally triggered ecological degradation. We discuss the practical implications of setting P-based nutrient criteria to protect and improve river water quality and ecology, drawing on a case study from the Red River Basin in the United States. We conclude that the challenges facing nutrient management and eutrophication control bear the hallmarks of "postnormal" science, where uncertainties are large, management intervention is urgently required, and decision stakes are high. We argue a case for a more holistic approach to eutrophication management that includes more sophisticated regime-based nutrient criteria and considers other nutrient and pollutant controls and river restoration (e.g., physical habitat and functional food web interactions) to promote more resilient water quality and ecosystem functioning along the land-freshwater continuum. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  6. Methane distribution and transportation in Lake Chaohu: a shallow eutrophic lake in Eastern China

    Science.gov (United States)

    Zhang, L.; Shen, Q.

    2016-12-01

    Global warming and eutrophication are two world widely concerned environmental problems. Methane is the second important greenhouse gas, and lake has been proven as a quite important natural source of methane emission. More methane may emit from eutrophic lake due to the higher organic matter deposition in the lake sediment. Lake Chaohu is a large and shallow eutrophic lake in eastern China (N31°25' 31°43', E117°16' 117°05'), with an area of 770 km2 and a mean depth of 2.7 m. To examine methane distribution and transportation in this eutrophic lake, field study across different seasons was carried out with 20 study sites in the lake. Samples from the different water and sediment depth was collected using headspace bottle, and methane content was measured by gas chromatography using a flame ionization detector. The potential methane production in the sediment was examined by an indoor incubation experiment. Methane flux from sediment to the overlying water was calculated by Fick's law, and methane emission from surface to the air was calculated at the same time. The results indicates that more methane accumulated in the water of northwestern bay in this lake, and higher methane release rates was also found at this area. Methane increases gradually with depth in the top 10 cm in sediment cores, then it almost keeps at constant state in the deeper sediment. In the sediment from northwestern bay, more methane content and the higher potential methane production was found compared to the sediment from the east area of this lake.

  7. Point Charges and Polygonal Linkages

    NARCIS (Netherlands)

    Khimshiashvili, Giorgi; Panina, Gaiane; Siersma, Dirk; Zolotov, Vladimir

    We investigate the critical points of Coulomb potential of point charges placed at the vertices of a planar polygonal linkage. It is shown that, for a collection of positive charges on a pentagonal linkage, there is a unique critical point in the set of convex configurations which is the point of

  8. A Formalization of Linkage Analysis

    DEFF Research Database (Denmark)

    Ingolfsdottir, Anna; Christensen, A.I.; Hansen, Jens A.

    In this report a formalization of genetic linkage analysis is introduced. Linkage analysis is a computationally hard biomathematical method, which purpose is to locate genes on the human genome. It is rooted in the new area of bioinformatics and no formalization of the method has previously been ...

  9. The dilemma of controlling cultural eutrophication of lakes.

    Science.gov (United States)

    Schindler, David W

    2012-11-07

    The management of eutrophication has been impeded by reliance on short-term experimental additions of nutrients to bottles and mesocosms. These measures of proximate nutrient limitation fail to account for the gradual changes in biogeochemical nutrient cycles and nutrient fluxes from sediments, and succession of communities that are important components of whole-ecosystem responses. Erroneous assumptions about ecosystem processes and lack of accounting for hysteresis during lake recovery have further confused management of eutrophication. I conclude that long-term, whole-ecosystem experiments and case histories of lake recovery provide the only reliable evidence for policies to reduce eutrophication. The only method that has had proven success in reducing the eutrophication of lakes is reducing input of phosphorus. There are no case histories or long-term ecosystem-scale experiments to support recent claims that to reduce eutrophication of lakes, nitrogen must be controlled instead of or in addition to phosphorus. Before expensive policies to reduce nitrogen input are implemented, they require ecosystem-scale verification. The recent claim that the 'phosphorus paradigm' for recovering lakes from eutrophication has been 'eroded' has no basis. Instead, the case for phosphorus control has been strengthened by numerous case histories and large-scale experiments spanning several decades.

  10. Eutrophication monitoring for Lake Superior's Chequamegon ...

    Science.gov (United States)

    A priority for the Lake Superior CSMI was to identify susceptible nearshore eutrophication areas. We developed an integrated sampling design to collect baseline data for Lake Superior’s Chequamegon Bay to understand how nearshore physical processes and tributary loading relate to observed chlorophyll concentrations. Sampling included ship-based water samples combined with vertical CTD casts, continuous in situ towing and data collected from an autonomous underwater glider. Sampling was conducted during June, July and September. The glider collected regional data as part of three extended missions in Lake Superior over the same periods. During the study, two significant storm events impacted the western end of Lake Superior; the first occurred during July 11-12, with 8-10 inches of rain in 24hrs, and the second on July 21 with winds in excess of 161 km/h. Using GIS software, we organized these diverse temporal data sets along a continuous time line with temporally coincident Modis Satellite data to visualize surface sediment plumes in relation to water quality measurements. Preliminary results suggest that both events impacted regional water quality, and that nearshore physical forces (upwelling and currents) influenced the spatial variability. Results comparing in situ measures with remotely sensed images will be discussed. not applicable

  11. The score statistic of the LD-lod analysis: detecting linkage adaptive to linkage disequilibrium.

    Science.gov (United States)

    Huang, J; Jiang, Y

    2001-01-01

    We study the properties of a modified lod score method for testing linkage that incorporates linkage disequilibrium (LD-lod). By examination of its score statistic, we show that the LD-lod score method adaptively combines two sources of information: (a) the IBD sharing score which is informative for linkage regardless of the existence of LD and (b) the contrast between allele-specific IBD sharing scores which is informative for linkage only in the presence of LD. We also consider the connection between the LD-lod score method and the transmission-disequilibrium test (TDT) for triad data and the mean test for affected sib pair (ASP) data. We show that, for triad data, the recessive LD-lod test is asymptotically equivalent to the TDT; and for ASP data, it is an adaptive combination of the TDT and the ASP mean test. We demonstrate that the LD-lod score method has relatively good statistical efficiency in comparison with the ASP mean test and the TDT for a broad range of LD and the genetic models considered in this report. Therefore, the LD-lod score method is an interesting approach for detecting linkage when the extent of LD is unknown, such as in a genome-wide screen with a dense set of genetic markers. Copyright 2001 S. Karger AG, Basel

  12. Organizational Linkages: Understanding the Productivity Paradox,

    Science.gov (United States)

    1994-01-01

    Ohio State University DAVID A. WHETTEN , Department of Business Administration, University of Illinois iii COMMITTEE ON HUMAN FACTORS RAYMOND S...DOWNSIZING 262 David A. Whetten and Kim S. Cameron 12 CONCLUSIONS 291 INDEX 302 Foreword The Committee on Human Factors was established in October 1980 by...expected to lead directly to increased organizational productivity. Using the perspective of organizational linkages, Whetten and Cameron examine this

  13. Eutrophication History of Small Shallow Lakes in Estonia: Evidence from Multiproxy Analysis of Lake Sediments

    Science.gov (United States)

    Koff, T.; Marzecova, A.; Vandel, E.; Mikomägi, A.; Avi, E.

    2015-12-01

    Human activities have impacted aquatic systems through the release of contaminants and the regulation of surface and groundwater. Although environmental monitoring has been essential in detecting eutrophication, biodiversity loss or water quality deterioration, monitoring activities are limited in time and are thus not sufficient in their scope to identify causality and thresholds. Paleolimnological studies increasingly show that the response of lakes to climatic and human influences is complex, multidimensional, and often indirectly mediated through watershed processes. In this study we examine the history of eutrophication processes in small lakes in Estonia using the multi-proxy analysis of sediment. Study sites represent lakes with different anthropogenic stressors: urbanisation and recreational use, run-off from an oil shale mine, and fish-kills and liming measures. We have used diverse analytical methods, such as elemental analysis, stable isotopes, fossil pigments, diatoms and Cladocera remains. The information derived from sedimentary indicators broadly agrees with the historical evidence of eutrophication and pollution. Moreover, the sediment records are indispensable for identifying additional issues such as: 1) earlier onset of cultural eutrophication; 2) the significant impact of catchment erosion on the deterioration of lake quality, particularly cyanobacterial blooms; and 3) changes in sedimentation processes with significance for internal biogeochemical cycling of nutrients. Importantly, the integration of several methods has significantly improved interpretation of sedimentary data and elucidated the different strengths of various indicator types. The project findings prove to be highly relevant for both the prediction of the ecological responses of lakes to different anthropogenic impacts and the establishment of reasonable reference target conditions in restoration schemes, as well as for methodological improvements of the sediment analysis.

  14. Virioplankton distribution and activity in a tropical eutrophicated bay

    Science.gov (United States)

    Bettarel, Yvan; Arfi, Robert; Bouvier, Thierry; Bouvy, Marc; Briand, Enora; Colombet, Jonathan; Corbin, Daniel; Sime-Ngando, Télesphore

    2008-11-01

    The study of lysogeny in aquatic systems is an often overlooked aspect of microbial ecology, especially in tropical environments. Herein, the fraction of lysogenized cells (FLC) was detected in the surface waters of 20 coastal stations distributed from the eutrophicated shoreline to seaward waters of Hann Bay (Senegal). Concurrently, viral lytic infection rates were extrapolated from the frequency of visibly infected bacterial cells (FVIC), as determined from transmission electron microscopy observations. The experimental induction of prophage was observed in less than 3% of indigenous marine bacteria, suggesting that lysogenic stages of infection are rare in Hann Bay. Similarly, only 0.5-4.7% of bacteria showed visible signs of lytic infection. However, the positive correlation between the fraction of lysogenic and lytic cells ( r = 0.67, p < 0.05, n = 20) may actually indicate that the coexistence of both lifestyles may be due to the massive and rapid induction of lysogens, potentially from the high levels of local UV radiation. Overall, we suggest that the determination of FVIC and FLC to examine the predominance of one type of cycle versus the other may be a source of misinterpretation in some particular aquatic environments.

  15. North-South Business Linkages

    DEFF Research Database (Denmark)

    Sørensen, Olav Jull; Kuada, John

    2006-01-01

    Based on empirical studies of linkages between TNCs and local firms in India, Malaysia, Vietnam, Ghana and South Africa, five themes are discussed and related to present theoretical perspectives. The themes are (1) Linakge Governance; (2) Globalisation and the dynamics in developing countries (the...... TNC-driven markets in developing countries); (3) The upgrading impact of FDI; (4) Non-equity linkages as a platform for business development, and (5) The learning perspective on international business linakges. The chapter offers at the end a three-dimanional model for impacts of business linkages....

  16. Sewage-effluent phosphorus: a greater risk to river eutrophication than agricultural phosphorus?

    Science.gov (United States)

    Jarvie, Helen P; Neal, Colin; Withers, Paul J A

    2006-05-01

    Phosphorus (P) concentrations from water quality monitoring at 54 UK river sites across seven major lowland catchment systems are examined in relation to eutrophication risk and to the relative importance of point and diffuse sources. The over-riding evidence indicates that point (effluent) rather than diffuse (agricultural) sources of phosphorus provide the most significant risk for river eutrophication, even in rural areas with high agricultural phosphorus losses. Traditionally, the relative importance of point and diffuse sources has been assessed from annual P flux budgets, which are often dominated by diffuse inputs in storm runoff from intensively managed agricultural land. However, the ecological risk associated with nuisance algal growth in rivers is largely linked to soluble reactive phosphorus (SRP) concentrations during times of ecological sensitivity (spring/summer low-flow periods), when biological activity is at its highest. The relationships between SRP and total phosphorus (TP; total dissolved P+suspended particulate P) concentrations within UK rivers are evaluated in relation to flow and boron (B; a tracer of sewage effluent). SRP is the dominant P fraction (average 67% of TP) in all of the rivers monitored, with higher percentages at low flows. In most of the rivers the highest SRP concentrations occur under low-flow conditions and SRP concentrations are diluted as flows increase, which is indicative of point, rather than diffuse, sources. Strong positive correlations between SRP and B (also TP and B) across all the 54 river monitoring sites also confirm the primary importance of point source controls of phosphorus concentrations in these rivers, particularly during spring and summer low flows, which are times of greatest eutrophication risk. Particulate phosphorus (PP) may form a significant proportion of the phosphorus load to rivers, particularly during winter storm events, but this is of questionable relevance for river eutrophication

  17. From Enclave to Linkage Economies?

    DEFF Research Database (Denmark)

    Hansen, Michael W.

    as the enclave economy par excellence, moving in with fully integrated value chains, extracting resources and exporting them as commodities having virtually no linkages to the local economy. However, new opportunities for promoting linkages are offered by changing business strategies of local African enterprises...... as well as foreign multinational corporations (MNCs). MNCs in extractives are increasingly seeking local linkages as part of their efficiency, risk, and asset-seeking strategies, and linkage programmes are becoming integral elements in many MNCs’ corporate social responsibility (CSR) activities....... At the same time, local African enterprises are eager to, and increasingly capable of, linking up to the foreign investors in order to expand their activities and acquire technology, skills and market access. The changing strategies of MNCs and the improving capabilities of African enterprises offer new...

  18. Establishing eutrophication assessment standards for four lake regions, China.

    Science.gov (United States)

    Huo, Shouliang; Ma, Chunzi; Xi, Beidou; Su, Jing; Zan, Fengyu; Ji, Danfeng; He, Zhuoshi

    2013-10-01

    The trophic status assessment of lakes in different lake regions may provide important and fundamental information for lake trophic state classification and eutrophication control. In this study, a region-specific lake eutrophication assessment standard was established through a frequency distribution method based on chlorophyll-a concentration. The assessment standards under the oligotrophic state for lakes in the Eastern plain, Yungui Plateau, Northeast Plain and Mountain Mongolia-Xinjiang regions are total phosphorus of 0.068, 0.005, 0.011, 0.005 mg/L; total nitrogen of 1.00, 0.16, 0.37, 0.60 mg/L; Secchi depth of 0.60, 8.00, 1.55, 3.00 m; and COD(Mn) of 2.24, 1.00, 5.11, 4.00 mg/L, respectively. Moreover, a region-specific comprehensive trophic level index was developed to provide an understandable assessment method for the public. The results indicated that the frequency distribution analysis based on chlorophyll-a combined with trophic level index provided a useful metric for the assessment of the lake trophic status. In addition, the difference of eutrophication assessment standards in different lake regions was analyzed, which suggested that the sensitivities of algae to nutrients and the assessment standard of trophic status possessed significant regional differences for the four lake ecoregions. Lake eutrophication assessment standards would contribute to maximizing the effectiveness of future management strategies, to control and minimize lake eutrophication problems.

  19. [Lake eutrophication modeling in considering climatic factors change: a review].

    Science.gov (United States)

    Su, Jie-Qiong; Wang, Xuan; Yang, Zhi-Feng

    2012-11-01

    Climatic factors are considered as the key factors affecting the trophic status and its process in most lakes. Under the background of global climate change, to incorporate the variations of climatic factors into lake eutrophication models could provide solid technical support for the analysis of the trophic evolution trend of lake and the decision-making of lake environment management. This paper analyzed the effects of climatic factors such as air temperature, precipitation, sunlight, and atmosphere on lake eutrophication, and summarized the research results about the lake eutrophication modeling in considering in considering climatic factors change, including the modeling based on statistical analysis, ecological dynamic analysis, system analysis, and intelligent algorithm. The prospective approaches to improve the accuracy of lake eutrophication modeling with the consideration of climatic factors change were put forward, including 1) to strengthen the analysis of the mechanisms related to the effects of climatic factors change on lake trophic status, 2) to identify the appropriate simulation models to generate several scenarios under proper temporal and spatial scales and resolutions, and 3) to integrate the climatic factors change simulation, hydrodynamic model, ecological simulation, and intelligent algorithm into a general modeling system to achieve an accurate prediction of lake eutrophication under climatic change.

  20. Overview of eutrophication indicators to assess environmental status within the European Marine Strategy Framework Directive

    Science.gov (United States)

    Ferreira, João G.; Andersen, Jesper H.; Borja, Angel; Bricker, Suzanne B.; Camp, Jordi; Cardoso da Silva, Margarida; Garcés, Esther; Heiskanen, Anna-Stiina; Humborg, Christoph; Ignatiades, Lydia; Lancelot, Christiane; Menesguen, Alain; Tett, Paul; Hoepffner, Nicolas; Claussen, Ulrich

    2011-06-01

    In 2009, following approval of the European Marine Strategy Framework Directive (MSFD, 2008/56/EC), the European Commission (EC) created task groups to develop guidance for eleven quality descriptors that form the basis for evaluating ecosystem function. The objective was to provide European countries with practical guidelines for implementing the MSFD, and to produce a Commission Decision that encapsulated key points of the work in a legal framework. This paper presents a review of work carried out by the eutrophication task group, and reports our main findings to the scientific community. On the basis of an operational, management-oriented definition, we discuss the main methodologies that could be used for coastal and marine eutrophication assessment. Emphasis is placed on integrated approaches that account for physico-chemical and biological components, and combine both pelagic and benthic symptoms of eutrophication, in keeping with the holistic nature of the MSFD. We highlight general features that any marine eutrophication model should possess, rather than making specific recommendations. European seas range from highly eutrophic systems such as the Baltic to nutrient-poor environments such as the Aegean Sea. From a physical perspective, marine waters range from high energy environments of the north east Atlantic to the permanent vertical stratification of the Black Sea. This review aimed to encapsulate that variability, recognizing that meaningful guidance should be flexible enough to accommodate the widely differing characteristics of European seas, and that this information is potentially relevant in marine ecosystems worldwide. Given the spatial extent of the MSFD, innovative approaches are required to allow meaningful monitoring and assessment. Consequently, substantial logistic and financial challenges will drive research in areas such as remote sensing of harmful algal blooms, in situ sensor development, and mathematical models. Our review takes into

  1. Reducing eutrophication increases spatial extent of communities supporting commercial fisheries

    DEFF Research Database (Denmark)

    Bauer, Barbara; Meier, H.E. Markus; Casini, Michele

    2018-01-01

    In this study we investigate if eutrophication management has the potential to substantially affect which areas are going to be most suitable for commercial fishing in the future. We use a spatial ecosystem model, forced by a coupled physical-biogeochemical model, to simulate the spatial distribu......In this study we investigate if eutrophication management has the potential to substantially affect which areas are going to be most suitable for commercial fishing in the future. We use a spatial ecosystem model, forced by a coupled physical-biogeochemical model, to simulate the spatial...... suitable for the commercially most valuable demersal fish predator and all types of fisheries. This suggests that strategic planning of fishery management strategies could benefit from considering future changes in species distributions due to changes in eutrophication. We show that combining approaches...

  2. Review on methodology for LCIA of marine eutrophication

    DEFF Research Database (Denmark)

    Larsen, Henrik Fred

    As part of the ongoing EU FP7 project LC-Impact (www.lc-impact.eu) new life cycle impact assessment (LCIA) methods are going to be developed and tested on industry cases. Among the life cycle assessment (LCA) impact categories in focus are aquatic eutrophication. As related to especially the marine...... environment very few and restricted attempts have yet been done on trying to include eutrophication in LCA. The aim of LC-Impact is to develop both a global and a spatial (and temporal) differentiated model, as both central fate processes, sensitivities of receiving environments (e.g. differences in limiting...... concentration and the potentially affected fraction of species in the marine ecosystem. This poster will present a review of the very limited existing attempts on how to include marine eutrophication in LCA and discuss alternative methodologies on how to model the environmental mechanism of this impact category....

  3. Worldwide Eutrophication of Water Bodies: Causes, Concerns, Controls

    Science.gov (United States)

    Prepas, E. E.; Charette, T.

    2003-12-01

    Eutrophication is the nutrient enrichment of waters that stimulates an array of symptomatic changes, that can include increased phytoplankton and rooted aquatic plant (macrophyte) production, fisheries and water quality deterioration, and other undesirable changes that interfere with water uses (Bartsch, 1972). The trophic state, or degree of fertility, of water bodies ranges from oligotrophic to mesotrophic to eutrophic with increasing supply of nutrients and organic matter ( Table 1). Eutrophication is most often the result of an elevated supply of nutrients, particularly nitrogen and phosphorus, to surface waters that results in enhanced production of primary producers, particularly phytoplankton and aquatic plants. Table 1. Mean annual values for the trophic classification system Total phosphorus (μg L-1)Chlorophyll a (μg L-1)Secchi disk depth (m) Ultra-oligotrophic12 Oligotrophic6 Mesotrophic10-352.5-86-3 Eutrophic35-1008-253-1.5 Hypertrophic>100>25effects of eutrophication because it can cause catastrophic fish kills, devastating local fisheries.The accumulation of plant biomass depends on the addition of factors that stimulate plant growth. On average, the macronutrients nitrogen and phosphorus are present in marine phytoplankton at an atomic ratio 16 : 1 (Redfield, 1958). The ratio of nitrogen to phosphorus in freshwaters tends to be greater than the ratio in phytoplankton; therefore, phosphorus most often limits the growth of phytoplankton. As a result, phosphorus enrichment of freshwater often causes its eutrophication ( Schindler, 1977). In lakes, nitrogen is usually present in concentrations equal to or beyond what is required for aquatic plant growth because, unlike phosphorus, it has an atmospheric source. In marine systems, nitrogen concentrations are often limiting because bacterial nitrogen fixation, while a considerable source of nitrogen in lakes, not as important in marine waters. A wide variety of prokaryotic organisms (i.e., certain

  4. Eutrophication and Warming Boost Cyanobacterial Biomass and Microcystins.

    Science.gov (United States)

    Lürling, Miquel; van Oosterhout, Frank; Faassen, Elisabeth

    2017-02-11

    Eutrophication and warming are key drivers of cyanobacterial blooms, but their combined effects on microcystin (MC) concentrations are less studied. We tested the hypothesis that warming promotes cyanobacterial abundance in a natural plankton community and that eutrophication enhances cyanobacterial biomass and MC concentrations. We incubated natural seston from a eutrophic pond under normal, high, and extreme temperatures (i.e., 20, 25, and 30 °C) with and without additional nutrients added (eutrophication) mimicking a pulse as could be expected from projected summer storms under climate change. Eutrophication increased algal- and cyanobacterial biomass by 26 and 8 times, respectively, and led to 24 times higher MC concentrations. This effect was augmented with higher temperatures leading to 45 times higher MC concentrations at 25 °C, with 11 times more cyanobacterial chlorophyll- a and 25 times more eukaryote algal chlorophyll- a . At 30 °C, MC concentrations were 42 times higher, with cyanobacterial chlorophyll- a being 17 times and eukaryote algal chlorophyll- a being 24 times higher. In contrast, warming alone did not yield more cyanobacteria or MCs, because the in situ community had already depleted the available nutrient pool. MC per potential MC producing cell declined at higher temperatures under nutrient enrichments, which was confirmed by a controlled experiment with two laboratory strains of Microcystis aeruginosa. Nevertheless, MC concentrations were much higher at the increased temperature and nutrient treatment than under warming alone due to strongly promoted biomass, lifting N-imitation and promotion of potential MC producers like Microcystis . This study exemplifies the vulnerability of eutrophic urban waters to predicted future summer climate change effects that might aggravate cyanobacterial nuisance.

  5. Eutrophication and Warming Boost Cyanobacterial Biomass and Microcystins

    Directory of Open Access Journals (Sweden)

    Miquel Lürling

    2017-02-01

    Full Text Available Eutrophication and warming are key drivers of cyanobacterial blooms, but their combined effects on microcystin (MC concentrations are less studied. We tested the hypothesis that warming promotes cyanobacterial abundance in a natural plankton community and that eutrophication enhances cyanobacterial biomass and MC concentrations. We incubated natural seston from a eutrophic pond under normal, high, and extreme temperatures (i.e., 20, 25, and 30 °C with and without additional nutrients added (eutrophication mimicking a pulse as could be expected from projected summer storms under climate change. Eutrophication increased algal- and cyanobacterial biomass by 26 and 8 times, respectively, and led to 24 times higher MC concentrations. This effect was augmented with higher temperatures leading to 45 times higher MC concentrations at 25 °C, with 11 times more cyanobacterial chlorophyll-a and 25 times more eukaryote algal chlorophyll-a. At 30 °C, MC concentrations were 42 times higher, with cyanobacterial chlorophyll-a being 17 times and eukaryote algal chlorophyll-a being 24 times higher. In contrast, warming alone did not yield more cyanobacteria or MCs, because the in situ community had already depleted the available nutrient pool. MC per potential MC producing cell declined at higher temperatures under nutrient enrichments, which was confirmed by a controlled experiment with two laboratory strains of Microcystis aeruginosa. Nevertheless, MC concentrations were much higher at the increased temperature and nutrient treatment than under warming alone due to strongly promoted biomass, lifting N-imitation and promotion of potential MC producers like Microcystis. This study exemplifies the vulnerability of eutrophic urban waters to predicted future summer climate change effects that might aggravate cyanobacterial nuisance.

  6. JLIN: A java based linkage disequilibrium plotter

    Directory of Open Access Journals (Sweden)

    McCaskie Pamela A

    2006-02-01

    Full Text Available Abstract Background A great deal of effort and expense are being expended internationally in attempts to detect genetic polymorphisms contributing to susceptibility to complex human disease. Techniques such as Linkage Disequilibrium mapping are being increasingly used to examine and compare markers across increasingly large datasets. Visualisation techniques are becoming essential to analyse the ever-growing volume of data and results available with any given analysis. Results JLIN (Java LINkage disequilibrium plotter is a software package designed for customisable, intuitive visualisation of Linkage Disequilibrium (LD across all common computing platforms. Customisation allows the user to choose particular visualisations, statistical measures and measurement ranges. JLIN also allows the user to export images of the LD visualisation in several common document formats. Conclusion JLIN allows the user to visually compare and contrast the results of a range of statistical measures on the input dataset(s. These measures include the commonly used D' and r2 statistics and empirical p-values. JLIN has a number of unique and novel features that improve on existing LD visualisation tools.

  7. Stream Macroinvertebrate Occurrence along Gradients in Organic Pollution and Eutrophication

    DEFF Research Database (Denmark)

    Friberg, Nikolai; Skriver, Jens; Larsen, Søren Erik

    2010-01-01

    We analysed a large number of concurrent samples of macroinvertebrate communities and chemical indicators of eutrophication and organic pollution [total-P, total-N, NH4-N, biological oxygen demand (BOD5)] from 594 Danish stream sites. Samples were taken over an 11-year time span as part of the Da......We analysed a large number of concurrent samples of macroinvertebrate communities and chemical indicators of eutrophication and organic pollution [total-P, total-N, NH4-N, biological oxygen demand (BOD5)] from 594 Danish stream sites. Samples were taken over an 11-year time span as part...

  8. Eutrophication management in surface waters using lanthanum modified bentonite

    DEFF Research Database (Denmark)

    Copetti, Diego; Finsterle, Karin; Marziali, Laura

    2016-01-01

    This paper reviews the scientific knowledge on the use of a lanthanum modified bentonite (LMB) to manage eutrophication in surface water. The LMB has been applied in around 200 environments worldwide and it has undergone extensive testing at laboratory, mesocosm, and whole lake scales. The availa......This paper reviews the scientific knowledge on the use of a lanthanum modified bentonite (LMB) to manage eutrophication in surface water. The LMB has been applied in around 200 environments worldwide and it has undergone extensive testing at laboratory, mesocosm, and whole lake scales...

  9. Lake eutrophication as indicated by ERTS satellite imagery

    Science.gov (United States)

    Scherz, J. P.; Van Domelen, J. F.; Holtje, K.; Johnson, W.

    1975-01-01

    Light reflectance from water in the laboratory always correlates to the water quality parameter of turbidity. This turbidity is caused by suspended solids in the water and for a particular type of material there is a good correlation between the weight of these suspended solids and turbidity. However, this correlation is different for different types of material. When this suspended material is living green matter as in an eutrophic lake, the changes in reflectance can be detected as changes in brightness on a particular aerial image. Two test sites have shown that there is indeed a good correlation between the brightness on an ERTS image and lake eutrophication.

  10. Ocean acidification with (de)eutrophication will alter future phytoplankton growth and succession

    DEFF Research Database (Denmark)

    Flynn, Kevin J.; Darren, Clark R.; Mitra, Aditee

    2015-01-01

    Human activity causes ocean acidification (OA) though the dissolution of anthropogenically generated CO2 into seawater, and eutrophication through the addition of inorganic nutrients. Eutrophication increases the phytoplankton biomass that can be supported during a bloom, and the resultant uptake...

  11. From Greenland to green lakes: Cultural eutrophication and the loss of benthic pathways in lakes

    DEFF Research Database (Denmark)

    Vadeboncoeur, Y.; Jeppesen, E.; Zanden, M. J. V.

    2003-01-01

    Benthic community responses to lake eutrophication are poorly understood relative to pelagic responses. We compared phytoplankton and periphyton productivity along a eutrophication gradient in Greenland, U.S., and Danish lakes. Phytoplankton productivity increased along the phosphorus gradient (t...

  12. The Geochemical Record of Cultural Eutrophication and Remediation Efforts in Three Connecticut Lakes

    Science.gov (United States)

    Ku, T.; Bourne, H. L.; Tirtajana, S.; Nahar, M.; Kading, T.

    2009-12-01

    Cultural eutrophication is the process whereby human activity increases the amount of nutrients, primarily nitrogen and phosphorous, entering an aquatic ecosystem causing excessive biological growth. To reverse or decelerate cultural eutrophication, many regulatory agencies have implemented stringent laws intended to lower the flux of nutrients into impacted water bodies or have emplaced internal remediation systems designed to decrease primary productivity. To quantify the effects of cultural eutrophication and remediation efforts, we examined sedimentary histories of three eutrophic Connecticut lakes that record the transition from pre-anthropogenic conditions into eutrophication and through recent remediation. The three Connecticut lakes (Lake Waramaug, Beseck Lake, and Amos Lake) represent a range of remediation activities. Since 1983, Lake Waramaug has been the focus of significant remediation efforts including the installation of three hypolimnetic withdrawal / layer aeration systems, zoning regulations to limit runoff, and the stocking and seeding of fish and zooplankton. Beseck Lake has experienced episodic eutrophic conditions, in part due to failing septic systems, and in 2001, 433 residences were converted from septic systems to a city sewer system. Amos Lake serves as a cultural eutrophication end member as it has not has received any major remediation. Multiple freeze and gravity cores were collected from 2005-2008. Radiocarbon, Pb-210, Cs-137, Hg, and Pb measurements determined sediment ages. Organic C accumulation rates, C/N ratios, organic matter delta-15N, bulk sediment Fe and Al concentrations, and P speciation (labile, iron-bound, aluminum-bound, organic, and total) determined sediment and nutrient sources and accumulations. Dithionite-extractable iron, pyrite S, and pyrite delta-34S provided insight into changes in P-Fe-S cycling. The sediment cores represent the last few hundreds of years of lake history and, importantly, some Lake Waramaug

  13. EUTROPHICATION OF WATER RESERVOIRS AND ROLE OF MACROPHYTES IN THIS PROCESS

    OpenAIRE

    Joanna Jadwiga Sender; Cyprian Jaruga

    2017-01-01

    The paper presents the problem related with the process of eutrophication, with special emphasis on dam reservoirs. Eutrophication is a global process, threatening the water ecosystem on every continent. It often leads to their degradation. Particularly vulnerable to eutrophication are artificial reservoirs which are dam reservoirs. This paper describes the mechanisms of eutrophication. We also pointed to the importance of aquatic plants in the process of water purification, as well as the po...

  14. Cost-efficient eutrophication control in a shallow lake ecosystem subject to two steady states

    NARCIS (Netherlands)

    Hein, L.G.

    2006-01-01

    Eutrophication of water bodies is a common problem in many countries. Eutrophication processes are guided by thresholds, which must be taken into account in the formulation of optimal policies for eutrophication control. Whereas a range of general models have been developed to determine the point of

  15. Eutrophication-driven deoxygenation in the coastal ocean

    NARCIS (Netherlands)

    Rabalais, N.N.; Cai, W.-J.; Carstensen, J.; Conley, D.J.; Fry, B.; Hu, X.; Quiñones-Rivera, Z.; Rosenberg, R.; Slomp, C.P.|info:eu-repo/dai/nl/159424003; Turner, R.E.; Voss, M.; Wissel, X.; Zhang, J.

    2014-01-01

    Human activities, especially increased nutrient loads that set in motion a cascading chain of events related to eutrophication, accelerate development of hypoxia (lower oxygen concentration) in many areas of the world's coastal ocean. Climate changes and extreme weather events may modify hypoxia.

  16. Eutrophication: Present reality and future challenges for South Africa

    African Journals Online (AJOL)

    1980-08-01

    Aug 1, 1980 ... Keywords: biomanipulation, cyanobacteria, eutrophication, forward prediction, management, low-p detergents, phosphorus, zero-phosphate .... problems and management options after 2000 (Quayle et al.,. 2010; Van Ginkel et al., 2009). .... This perspective prompted the re- investigation of means to control ...

  17. Eutrophication, microbial-sulfate reduction and mass extinctions

    DEFF Research Database (Denmark)

    Schobben, Martin; Stebbins, Alan; Ghaderi, Abbas

    2016-01-01

    to the Earth system, notably, the biogeochemical sulfur and carbon cycle. This climate warming feedback produces large-scale eutrophication on the continental shelf, which, in turn, expands oxygen minimum zones by increased respiration, which can turn to a sulfidic state by increased microbial-sulfate...

  18. Urban lake system eutrophication – A case study | MAMA | Journal ...

    African Journals Online (AJOL)

    The dynamic eutrophication process study of Yamoussoukro lake system in Côte d'Ivoire was carried out from February 1997 to January 1998. It appeared that this phenomenon is related to the nutriments that are phosphorus mainly and nitrogen. It was shown that the fluctuations of these nutriments depend on the climatic ...

  19. Agriculture and eutrophication of freshwaters: a review of control ...

    African Journals Online (AJOL)

    Agriculture contributes a larger percentage of phosphorus (P) to freshwaters eutrophication. Fertilizers and manures applications over a period of time lead to P soil build up exceeding the required needs of the crops. Excess P is transferred into the waters through runoff, erosion, leaching and artificial drainage which ...

  20. Towards the classification of eutrophic condition in estuaries

    CSIR Research Space (South Africa)

    Lemley, DA

    2015-10-01

    Full Text Available to the success of these programmes is the use of indicators, as they transform data into useful information. The aim of this study was to identify the eutrophic condition of selected estuaries along the southern coast of South Africa, using a multi...

  1. Strategies for Control of Man-Made Eutrophication

    Science.gov (United States)

    Grundy, Richard D.

    1971-01-01

    The key concerns for both long- and short-term control strategies for cultural eutrophication are: (1) controls which reflect the regional character of the problem, and (2) concern for the potential public health and environmental implications of the nonphosphate detergent formulations. (Author/CP)

  2. Macroalgal mats in a eutrophic lagoon : dynamics and control mechanisms

    NARCIS (Netherlands)

    Malta, Erik-jan

    2000-01-01

    One of the most striking phenomena of eutrophication in shallow coastal waters is the mass accumulation of macroalgae. These macroalgal blooms have a negative effect on the functioning of the ecosystem, fisheries activities and tourism. This thesis focuses on the regulation of seasonal and spatial

  3. Phosphorus dynamics in the sediment of a eutrophic lake

    NARCIS (Netherlands)

    Sinke, A.J.C.

    1992-01-01

    Since the sixties eutrophication has been recognized to affect the quality of surface waters. The prolonged loading with nutrients has led to high algal concentrations in the water and to concommitant environmental problems such as the depletion of oxygen, the production of toxins and the

  4. Eutrophication alters Si cycling and litter decomposition in wetlands

    NARCIS (Netherlands)

    Emsens, Willem-Jan; Schoelynck, Jonas; Grootjans, Ab P.; Struyf, Eric; van Diggelen, Rudy

    2016-01-01

    Anthropogenic eutrophication of wetlands may have a significant impact on the global biogeochemical silicon (Si) cycle, as Si filtering by wetland vegetation codetermines fluxes of Si towards the oceans. We experimentally investigated how macronutrient (NPK) enrichment alters total Si storage and Si

  5. Model studies on the eutrophication of shallow lakes and ditches

    NARCIS (Netherlands)

    Janse, J.H.

    2005-01-01

    This study concentrates on eutrophication effects in shallow lakes and ponds on the one hand and in ditches (small water channels in agricultural areas) on the other. In shallow lakes (up to ca 4 m of depth), ihe clear-water community characterized by macrophytes is generally replaced by a dominance

  6. Classifying aquatic macrophytes as indicators of eutrophication in European lakes

    NARCIS (Netherlands)

    Penning, W.E.; Mjelde, M.; Dudley, B.; Hellsten, S.; Hanganu, J.; Kolada, A.; van den Berg, Marcel S.; Poikane, S.; Phillips, G.; Willby, N.; Ecke, F.

    2008-01-01

    Aquatic macrophytes are one of the biological quality elements in the Water Framework Directive (WFD) for which status assessments must be defined. We tested two methods to classify macrophyte species and their response to eutrophication pressure: one based on percentiles of occurrence along a

  7. STAKEHOLDER LINKAGES FOR SUSTAINABLE LAND ...

    African Journals Online (AJOL)

    Osondu

    These stakeholders were found having different interests regarding SLM issues. The linkages of farmers with DAs and RKA offices were observed to be strong but farmers' participation in new technology selection was found to be low. Farmer interactions with Woreda,. Zone and Region level experts were observed to be ...

  8. Data linkage dynamics with shedding

    NARCIS (Netherlands)

    Bergstra, J.A.; Middelburg, C.A.

    2008-01-01

    We study shedding in the setting of data linkage dynamics, a simple model of computation that bears on the use of dynamic data structures in programming. Shedding is complementary to garbage collection. With shedding, each time a link to a data object is updated by a program, it is determined

  9. Data linkage dynamics with shedding

    NARCIS (Netherlands)

    Bergstra, J.A.; Middelburg, C.A.

    2010-01-01

    We study shedding in the setting of data linkage dynamics, a simple model of computation that bears on the use of dynamic data structures in programming. Shedding is complementary to garbage collection. With shedding, each time a link to a data object is updated by a program, it is determined

  10. A linkage study of bipolar disorder

    Energy Technology Data Exchange (ETDEWEB)

    Kelsoe, J.R. [Univ. of California, San Diego (United States); Sadovnick, A.D.; Remick, R.A. [Univ. of British Columbia, Vancouver (Canada)] [and others

    1994-09-01

    We are currently surveying the genome with polymorphic DNA markers in search of loci linked to bipolar disorder (manic-depressive illness) in three populations: 20 families (175 subjects) from the general North American population from San Diego (UCSD) and Vancouver (UBC); 3 Icelandic families (55 subjects); and an Old Order Amish pedigree 110 (118 subjects). Over 50 markers on chromosomes 1, 2, 5, 11, 17, 18, 20 and 21 have been examined. All markers have been tested in the Amish and Icelandic families, and a portion of them in the UCSD/UBC families, which we have only recently begun genotyping. The following candidate genes have been examined: {beta}-TSH, dopamine transporter (HDAT), {beta}2 adrenergic receptor (ADRB2), glucocorticoid type II receptor (GRL), D2 dopamine receptor, serotonin transporter (HSERT), and G{alpha}s G protein subunit (GNAS1). Linkage analysis was conducted using an autosomal dominant model with age-dependent reduced penetrance. Subjects with bipolar, schizoaffective, or recurrent major depressive disorders were considered affected. No significant evidence for linkage was obtained. Mildly positive lods ranging between 1.1 and 1.6 were obtained for three loci: D11S29, HDAT, and GRL.

  11. An estimating function approach to linkage heterogeneity

    Indian Academy of Sciences (India)

    Testing linkage heterogeneity between two loci is an important issue in genetics. Currently, there are four methods (K-test, A-test, B-test and D-test) for testing linkage heterogeneity in linkage analysis, which are based on the likelihood-ratio test. Among them, the commonly used methods are the K-test and A-test.

  12. Remediation of eutrophic water using Lemna minor in a controlled ...

    African Journals Online (AJOL)

    There was oxidative damage at temperatures of less than 10 °C and greater than 40 °C. The pH of the growth medium was inversely related to the growth responses of Lemna minor. At acidic pH and at temperatures between 20 and 30 °C, the environmental conditions were most suitable for phytoremediation of eutrophic ...

  13. Historical records of coastal eutrophication-induced hypoxia

    Directory of Open Access Journals (Sweden)

    A. J. Gooday

    2009-08-01

    Full Text Available Under certain conditions, sediment cores from coastal settings subject to hypoxia can yield records of environmental changes over time scales ranging from decades to millennia, sometimes with a resolution of as little as a few years. A variety of biological and geochemical indicators (proxies derived from such cores have been used to reconstruct the development of eutrophication and hypoxic conditions over time. Those based on (1 the preserved remains of benthic organisms (mainly foraminiferans and ostracods, (2 sedimentary features (e.g. laminations and (3 sediment chemistry and mineralogy (e.g. presence of sulphides and redox-sensitive trace elements reflect conditions at or close to the seafloor. Those based on (4 the preserved remains of planktonic organisms (mainly diatoms and dinoflagellates, (5 pigments and lipid biomarkers derived from prokaryotes and eukaryotes and (6 organic C, N and their stable isotope ratios reflect conditions in the water column. However, the interpretation of these indicators is not straightforward. A central difficulty concerns the fact that hypoxia is strongly correlated with, and often induced by, organic enrichment caused by eutrophication, making it difficult to separate the effects of these phenomena in sediment records. The problem is compounded by the enhanced preservation in anoxic and hypoxic sediments of organic microfossils and biomarkers indicating eutrophication. The use of hypoxia-specific proxies, such as the trace metals molybdenum and rhenium and the bacterial biomarker isorenieratene, together with multi-proxy approaches, may provide a way forward. All proxies of bottom-water hypoxia are basically qualitative; their quantification presents a major challenge to which there is currently no satisfactory solution. Finally, it is important to separate the effects of natural ecosystem variability from anthropogenic effects. Despite these problems, in the absence of historical data for dissolved oxygen

  14. Prospective linkages between peer victimization and externalizing problems in children: a meta-analysis

    NARCIS (Netherlands)

    Reijntjes, A.; Kamphuis, J.H.; Prinzie, P.; Boelen, P.A.; van der Schoot, M.; Telch, M.J.

    2011-01-01

    Previous meta-analytic research has shown both concurrent and prospective linkages between peer victimization and internalizing problems in youth. However, the linkages between peer victimization and externalizing problems over time have not been systematically examined, and it is therefore unknown

  15. Prospective Linkages between Peer Victimization and Externalizing Problems in Children: A Meta-Analysis

    NARCIS (Netherlands)

    Reijntjes, A.; Kamphuis, J.H.; Prinzie, P.; Boelen, P.A.; van der Schoot, M.; Telch, M.J.

    2011-01-01

    Previous meta-analytic research has shown both concurrent and prospective linkages between peer victimization and internalizing problems in youth. However, the linkages between peer victimization and externalizing problems over time have not been systematically examined, and it is therefore unknown

  16. Eutrophication and the dietary promotion of sea turtle tumors

    Directory of Open Access Journals (Sweden)

    Kyle S. Van Houtan

    2014-09-01

    Full Text Available The tumor-forming disease fibropapillomatosis (FP has afflicted sea turtle populations for decades with no clear cause. A lineage of α-herpesviruses associated with these tumors has existed for millennia, suggesting environmental factors are responsible for its recent epidemiology. In previous work, we described how herpesviruses could cause FP tumors through a metabolic influx of arginine. We demonstrated the disease prevails in chronically eutrophied coastal waters, and that turtles foraging in these sites might consume arginine-enriched macroalgae. Here, we test the idea using High-Performance Liquid Chromatography (HPLC to describe the amino acid profiles of green turtle (Chelonia mydas tumors and five common forage species of macroalgae from a range of eutrophic states. Tumors were notably elevated in glycine, proline, alanine, arginine, and serine and depleted in lysine when compared to baseline samples. All macroalgae from eutrophic locations had elevated arginine, and all species preferentially stored environmental nitrogen as arginine even at oligotrophic sites. From these results, we estimate adult turtles foraging at eutrophied sites increase their arginine intake 17–26 g daily, up to 14 times the background level. Arginine nitrogen increased with total macroalgae nitrogen and watershed nitrogen, and the invasive rhodophyte Hypnea musciformis significantly outperformed all other species in this respect. Our results confirm that eutrophication substantially increases the arginine content of macroalgae, which may metabolically promote latent herpesviruses and cause FP tumors in green turtles.

  17. Does eutrophication-driven evolution change aquatic ecosystems?

    Science.gov (United States)

    Alexander, Timothy J; Vonlanthen, Pascal; Seehausen, Ole

    2017-01-19

    Eutrophication increases primary production and changes the relative abundance, taxonomic composition and spatial distribution of primary producers within an aquatic ecosystem. The changes in composition and location of resources alter the distribution and flow of energy and biomass throughout the food web. Changes in productivity also alter the physico-chemical environment, which has further effects on the biota. Such ecological changes influence the direction and strength of natural and sexual selection experienced by populations. Besides altering selection, they can also erode the habitat gradients and/or behavioural mechanisms that maintain ecological separation and reproductive isolation among species. Consequently, eutrophication of lakes commonly results in reduced ecological specialization as well as genetic and phenotypic homogenization among lakes and among niches within lakes. We argue that the associated loss in functional diversity and niche differentiation may lead to decreased carrying capacity and lower resource-use efficiency by consumers. We show that in central European whitefish species radiations, the functional diversity affected by eutrophication-induced speciation reversal correlates with community-wide trophic transfer efficiency (fisheries yield per unit phosphorus). We take this as an example of how evolutionary dynamics driven by anthropogenic environmental change can have lasting effects on biodiversity and ecosystem functioning.This article is part of the themed issue 'Human influences on evolution, and the ecological and societal consequences'. © 2016 The Author(s).

  18. Restoration in northern Lake Gehu, a eutrophic lake in China

    Science.gov (United States)

    Wu, Xiaodong; Li, Wenchao; Pan, Jizheng; Ma, Shuzhan; Chen, Bingfa; He, Shangwei

    2017-11-01

    Lake Gehu is a severely eutrophic lake in southeast China. A series of restoration measures have been implemented since 2009 in northern Lake Gehu. This study compared aquatic plants, water quality, sediment, and phytoplankton between restoration and control areas to investigate the effect of restoration measures. The results demonstrated that aquatic macrophyte coverage increased from 0% to 10.6%; mean TP, TN, and CODMn concentrations increased by 50.0%, 42.4%, and 40.8%, respectively, compared with those before the measures were carried out; the mean Secchi depth (SD) increased to 42.5 cm, which is 1.4 times higher than that before restoration; the mean euphotic depth (Zeu) in the summer increased from 91 to 130 cm; the mean chl a concentration decreased from 34.8 to 20.2 μg/L, compared with that before restoration; the Shannon-Wiener index of phytoplankton increased by 28.7%. The mean TP and TN concentrations in sediments decreased by 63.8% and 52.4%, respectively, compared with that before dredging. These results indicate that the restoration in northern Lake Gehu was effective. To complete the transformation from an algae- to a macrophyte-stable state within the region, further measures must be adopted. This restoration of a eutrophic lake can serve as a reference for similar eutrophic lakes.

  19. Eutrophication and the dietary promotion of sea turtle tumors.

    Science.gov (United States)

    Van Houtan, Kyle S; Smith, Celia M; Dailer, Meghan L; Kawachi, Migiwa

    2014-01-01

    The tumor-forming disease fibropapillomatosis (FP) has afflicted sea turtle populations for decades with no clear cause. A lineage of α-herpesviruses associated with these tumors has existed for millennia, suggesting environmental factors are responsible for its recent epidemiology. In previous work, we described how herpesviruses could cause FP tumors through a metabolic influx of arginine. We demonstrated the disease prevails in chronically eutrophied coastal waters, and that turtles foraging in these sites might consume arginine-enriched macroalgae. Here, we test the idea using High-Performance Liquid Chromatography (HPLC) to describe the amino acid profiles of green turtle (Chelonia mydas) tumors and five common forage species of macroalgae from a range of eutrophic states. Tumors were notably elevated in glycine, proline, alanine, arginine, and serine and depleted in lysine when compared to baseline samples. All macroalgae from eutrophic locations had elevated arginine, and all species preferentially stored environmental nitrogen as arginine even at oligotrophic sites. From these results, we estimate adult turtles foraging at eutrophied sites increase their arginine intake 17-26 g daily, up to 14 times the background level. Arginine nitrogen increased with total macroalgae nitrogen and watershed nitrogen, and the invasive rhodophyte Hypnea musciformis significantly outperformed all other species in this respect. Our results confirm that eutrophication substantially increases the arginine content of macroalgae, which may metabolically promote latent herpesviruses and cause FP tumors in green turtles.

  20. A Prehistorical Record of Cultural Eutrophication from Crawford Lake, Canada

    Energy Technology Data Exchange (ETDEWEB)

    Ekdahl, E J; Teranes, J; Guilderson, T; Turton, C L; McAndrews, J H; Wittkop, C A; Stoermer, E F

    2004-08-05

    Cultural eutrophication--the process by which human activities increase nutrient input rates to aquatic ecosystems and thereby cause undesirable changes in surface-water quality--is generally thought to have begun with the start of the industrial era. The prehistoric dimension of human impacts on aquatic ecosystems remains relatively undescribed, particularly in North America. Here we present fossil plankton data (diatoms and rotifers), organic and inorganic carbon accumulations, and carbon isotope ratios from a 1000-yr sediment core record from Crawford Lake, Ontario, Canada. The data documents increased nutrient input to Crawford Lake caused by Iroquoian horticultural activity from A.D. 1268 to 1486 and shows how this increased nutrient input elevated lake productivity, caused bottom-water anoxia, and irreversibly altered diatom community structure within just a few years. Iroquoian settlement in the region declined in the fifteenth century, yet diatom communities and lake circulation never recovered to the predisturbance state. A second phase of cultural eutrophication starting in A.D. 1867, initiated by Canadian agricultural disturbance, increased lake productivity but had comparatively less of an impact on diatom assemblages and carbon-storage pathways than the initial Iroquoian disturbance. This study deepens our understanding of the impact of cultural eutrophication on lake systems, highlights the lasting influence of initial environmental perturbation, and contributes to the debate on the ecological impacts of density and agricultural practices of native North American inhabitants.

  1. Lake Baikal Ecosystem Faces the Threat of Eutrophication

    Directory of Open Access Journals (Sweden)

    Galina I. Kobanova

    2016-01-01

    Full Text Available Recently there have been reports about large accumulations of algae on the beaches of Lake Baikal, the oldest and deepest freshwater body on earth, near major population centers and in areas with large concentrations of tourists and tourism infrastructure. To evaluate the observations indicating the ongoing process of eutrophication of Lake Baikal, a field study in July 2012 in the two largest bays of Lake Baikal, Barguzinsky and Chivyrkuisky, was organized. The study of phytoplankton using the sedimentary method and quantitative records of accumulations of macrophytes in the surf zone was made. In Chivyrkuisky Bay, we found the massive growth of colorless flagellates and cryptomonads as well as the aggregations of Elodea canadensis along the sandy shoreline (up to 26 kg/m2. Barguzinsky Bay registered abundantly cyanobacterial Anabaena species, cryptomonads, and extremely high biomass of Spirogyra species (up to 70 kg/m3. The results show the presence of local but significant eutrophication of investigated bays. To prevent further extensions of this process in unique ecosystem of Lake Baikal, the detailed study and monitoring of the coastal zone, the identification of the sources of eutrophication, and the development of measures to reduce nutrient inputs in the waters are urgently needed.

  2. Growth rate of Ulva rigida in different Mediterranean eutrophicated sites.

    Science.gov (United States)

    de Casabianca, M L; Barthelemy, N; Serrano, O; Sfriso, A

    2002-03-01

    The growth of juvenile populations of Ulva rigida C. Agardh was measured by means of immersion in in situ cages against environmental parameters (temperature, incident light, salinity, dissolved inorganic nitrogen and dissolved reactive phosphorus) in four different eutrophicated southern sites: Channel of the Thau lagoon (France), Lido, Sacca Sessola and Fusina stations (Venice lagoon, Italy). The growth curves as a function of temperature showed that, in all cases, the maximal temperature for Ulva growth was 17 degrees C (limitation in growth below 7 degrees C and above around 25 degrees C). The growth analysis of these four sites showed seasonal differences. In the least eutrophicated and calmest Lido station, grazing and dissolved reactive phosphorus (seven times lower at Lido than at Thau) played a key role. At Thau and Fusina, which are eutrophicated and turbid environments, the incident light had a strong impact on growth. Sacca Sessola, with an intermediate position between the above two mentioned situations, showed the highest growth rate. The values and relative growth rate (RGR) curves of the Mediterranean and open-sea northern sites are discussed. In particular, the temperature defines the type of growth curve (unimodal or bimodal) and the incident light is responsible for the low Mediterranean RGR values (<10% day(-1)).

  3. Daphniid zooplankton assemblage shifts in response to eutrophication and metal contamination during the Anthropocene.

    Science.gov (United States)

    Rogalski, Mary Alta; Leavitt, Peter R; Skelly, David K

    2017-07-26

    Human activities during the Anthropocene result in habitat degradation that has been associated with biodiversity loss and taxonomic homogenization of ecological communities. Here we estimated effects of eutrophication and heavy metal contamination, separately and in combination, in explaining zooplankton species composition during the past 125-145 years using analysis of daphniid diapausing egg banks from four lakes in the northeastern USA. We then examined how these community shifts influenced patterns of diversity and homogenization. Analysis of past lake production (via subfossil pigments) and metal contamination (via sedimentary metals) demonstrated that eutrophication alone (19-39%) and in combination with metal pollution (17-54%) explained 36-79% of historical variation in daphniid species relative abundances in heavily fertilized lakes. In contrast, metal pollution alone explained the majority (72%) of historical variation in daphniid assemblages at the oligotrophic site. Several species colonization events in eutrophying lakes resulted in increased species richness and gamma diversity through time. At the same time, daphniid assemblages in three eutrophied lakes became more similar to each other (homogenized), but this pattern was only seen when accounting for species presence/absence. We did not observe consistent patterns of divergence between the assemblages in the eutrophying lakes and the low-nutrient reference site. Given the pervasive nature of fertilization and metal pollution, and the sensitivity of cladocerans to these factors, we suggest that many inhabited lake districts may already exhibit similar patterns of daphniid assemblage shifts. © 2017 The Author(s).

  4. Longitudinal heterogeneity of sediment characteristics during southwest monsoon season in hyper-eutrophic Krishnagiri reservoir, India.

    Science.gov (United States)

    Sudha, Velu; Ambujam, Neelakantapillai Kanniperumal

    2012-03-01

    Krishnagiri reservoir is a hyper-eutrophicated reservoir located in Krishnagiri district which is one of the drought-prone districts in Tamil Nadu, India. The reservoir water is being used for various purposes such as irrigation, drinking, fish rearing, livestock rearing, and recreation. Since there is no an evidence of investigation on bottom sediments in Krishnagiri reservoir, the present study was carried out during southwest monsoon season in 2008. This study examined the physical and chemical characteristics of the bottom sediments such as composition, redox potential, moisture content, organic carbon, organic matter, total phosphorus, and total iron at 15 locations in the reservoir. Phosphorus fractionation study was carried out to find out different fractions such as loosely adsorbed phosphorous, iron and aluminium-bound phosphorus, calcium-bound phosphorous, and organic phosphorous. Results indicated that there was spatial variation in the composition of sediments and low values of redox potential. The significant positive correlation exists between the organic carbon and organic phosphorus concentration. The lacustrine zone of the reservoir showed high accumulation of total phosphorus and total iron when compared to riverine and transition zones. This study concludes an allogenic origin of majority of inorganic phosphorus in the reservoir during the study period and this might have been derived from the catchment during the erosion process. The high concentration of surface sediment phosphorus clearly indicates a greater threat of eutrophication in Krishnagiri reservoir.

  5. Linkage Behavior and Practices of Agencies in the Agricultural ...

    African Journals Online (AJOL)

    The study examined the linkage behaviour and practices of agencies in the agricultural innovation transfer sub system in Southeastern Nigeria. A total sample size of 210 respondents purposively selected from ADPs(60), LGs(60), profit NGOs(60), non- profit NGOs(30) were used. Data were collected by the use of ...

  6. Linkages over Time between Adolescents' Relationships with Parents and Friends

    Science.gov (United States)

    De Goede, Irene H. A.; Branje, Susan J. T.; Delsing, Marc J. M. H.; Meeus, Wim H. J.

    2009-01-01

    This 5-wave longitudinal study examines linkages over time between adolescents' perceptions of relationships with parents and friends with respect to support, negative interaction, and power. A total of 575 early adolescents (54.1% boys) and 337 middle adolescents (43.3% boys) participated. Path analyses mainly showed bidirectional associations…

  7. Re-inventing the Future: Linkages between Human Rights, Foreign ...

    African Journals Online (AJOL)

    This paper raises questions concerning the emerging trends of regional and international relations. In this endeavour, it examines new insights from traditional perspectives. The paper explores the outer contours of the conceptual linkages between human rights, foreign policy and regional integration in the East African ...

  8. Privacy preserving interactive record linkage (PPIRL).

    Science.gov (United States)

    Kum, Hye-Chung; Krishnamurthy, Ashok; Machanavajjhala, Ashwin; Reiter, Michael K; Ahalt, Stanley

    2014-01-01

    Record linkage to integrate uncoordinated databases is critical in biomedical research using Big Data. Balancing privacy protection against the need for high quality record linkage requires a human-machine hybrid system to safely manage uncertainty in the ever changing streams of chaotic Big Data. In the computer science literature, private record linkage is the most published area. It investigates how to apply a known linkage function safely when linking two tables. However, in practice, the linkage function is rarely known. Thus, there are many data linkage centers whose main role is to be the trusted third party to determine the linkage function manually and link data for research via a master population list for a designated region. Recently, a more flexible computerized third-party linkage platform, Secure Decoupled Linkage (SDLink), has been proposed based on: (1) decoupling data via encryption, (2) obfuscation via chaffing (adding fake data) and universe manipulation; and (3) minimum information disclosure via recoding. We synthesize this literature to formalize a new framework for privacy preserving interactive record linkage (PPIRL) with tractable privacy and utility properties and then analyze the literature using this framework. Human-based third-party linkage centers for privacy preserving record linkage are the accepted norm internationally. We find that a computer-based third-party platform that can precisely control the information disclosed at the micro level and allow frequent human interaction during the linkage process, is an effective human-machine hybrid system that significantly improves on the linkage center model both in terms of privacy and utility.

  9. Nutrient and grazing factors in relation to phytoplankton level in a eutrophic shallow lake: the effect of low macrophyte abundance.

    Science.gov (United States)

    Lau, S S S; Lane, S N

    2002-08-01

    The ability of submerged macrophytes to moderate the structure of food webs with respect to lake eutrophication management has been intensively studied in recent years. Many lake managers have adopted the option of increasing macrophyte abundance in order to restore eutrophic waters, with a view to improve water quality, increase water transparency and reduce phytoplankton biomass. These studies are mostly based upon the comparison of macrophyte-rich and macrophyte-free waters. There is less quantitative information on how different levels of macrophyte abundance, in particular very low levels, influence ecosystem structure, or vice versa, within the same ecosystem. This paper takes a multivariate statistical approach to examine ecosystem function with low macrophyte abundance (ca. 5%) in the context of nutrient-phytoplankton-zooplankton interaction in a eutrophic shallow lake. It shows that with low levels of macrophyte coverage, phytoplankton biomass was only limited by nutrient (TP and Si) availability, whilst nutrient (Si) as well as grazing (zooplankton and Daphnia) factors were both limiting phytoplankton levels in macrophyte-free waters. With respect to interactions between Daphnia and chlorophyll-a, the results suggest that low macrophyte cover does not result in a reduction of phytoplankton biomass due to the presence of Daphnia. Rather, low macrophyte cover provides a refuge that maintains constant Daphnia predation, so reducing chlorophyll-a fluctuation. These results add credence to the causal interpretation of different interactions amongst nutrients, phytoplankton and zooplankton at very low macrophyte densities.

  10. When to conduct probabilistic linkage vs. deterministic linkage? A simulation study.

    Science.gov (United States)

    Zhu, Ying; Matsuyama, Yutaka; Ohashi, Yasuo; Setoguchi, Soko

    2015-08-01

    When unique identifiers are unavailable, successful record linkage depends greatly on data quality and types of variables available. While probabilistic linkage theoretically captures more true matches than deterministic linkage by allowing imperfection in identifiers, studies have shown inconclusive results likely due to variations in data quality, implementation of linkage methodology and validation method. The simulation study aimed to understand data characteristics that affect the performance of probabilistic vs. deterministic linkage. We created ninety-six scenarios that represent real-life situations using non-unique identifiers. We systematically introduced a range of discriminative power, rate of missing and error, and file size to increase linkage patterns and difficulties. We assessed the performance difference of linkage methods using standard validity measures and computation time. Across scenarios, deterministic linkage showed advantage in PPV while probabilistic linkage showed advantage in sensitivity. Probabilistic linkage uniformly outperformed deterministic linkage as the former generated linkages with better trade-off between sensitivity and PPV regardless of data quality. However, with low rate of missing and error in data, deterministic linkage performed not significantly worse. The implementation of deterministic linkage in SAS took less than 1min, and probabilistic linkage took 2min to 2h depending on file size. Our simulation study demonstrated that the intrinsic rate of missing and error of linkage variables was key to choosing between linkage methods. In general, probabilistic linkage was a better choice, but for exceptionally good quality data (<5% error), deterministic linkage was a more resource efficient choice. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Combining the ICM Eutrophication Model with the SEDZLJ Sediment Transport Model

    Science.gov (United States)

    2012-08-01

    ER D C/ EL T R -1 2 -1 7 Dredging Operations and Environmental Research Program Combining the ICM Eutrophication Model with the SEDZLJ...Dredging Operations and Environmental Research Program ERDC/EL TR-12-17 August 2012 Combining the ICM Eutrophication Model with the SEDZLJ...formulation of the SEDZLJ sediment transport model, coupling of the model with the ICM eutrophication model, validation of the combined codes on a

  12. Limited privacy protection and poor sensitivity: Is it time to move on from the statistical linkage key-581?

    Science.gov (United States)

    Randall, Sean M; Ferrante, Anna M; Boyd, James H; Brown, Adrian P; Semmens, James B

    2016-08-01

    The statistical linkage key (SLK-581) is a common tool for record linkage in Australia, due to its ability to provide some privacy protection. However, newer privacy-preserving approaches may provide greater privacy protection, while allowing high-quality linkage. To evaluate the standard SLK-581, encrypted SLK-581 and a newer privacy-preserving approach using Bloom filters, in terms of both privacy and linkage quality. Linkage quality was compared by conducting linkages on Australian health datasets using these three techniques and examining results. Privacy was compared qualitatively in relation to a series of scenarios where privacy breaches may occur. The Bloom filter technique offered greater privacy protection and linkage quality compared to the SLK-based method commonly used in Australia. The adoption of new privacy-preserving methods would allow both greater confidence in research results, while significantly improving privacy protection. © The Author(s) 2016.

  13. Eutrophication as a driver of r-selection traits in a freshwater fish.

    Science.gov (United States)

    Lin, M; Chevalier, M; Lek, S; Zhang, L; Gozlan, R E; Liu, J; Zhang, T; Ye, S; Li, W; Li, Z

    2014-08-01

    This study tested whether eutrophication could influence life-history traits of a cyprinid, Chanodichthys erythropterus, in 10 Chinese lakes. Using the von Bertalanffy growth model, the asymptotic length (L∞ ) and the growth performance index (IGRO ) were significantly affected by eutrophication. The gonado-somatic index (IG ) and relative fecundity (FR ) were significantly lower in mesotrophic lakes than in eutrophic and hypertrophic lakes. These results indicate that increasing eutrophication affects the life-history tactics of a freshwater fish. © 2014 The Fisheries Society of the British Isles.

  14. Dissolved organic carbon and its potential predictors in eutrophic lakes.

    Science.gov (United States)

    Toming, Kaire; Kutser, Tiit; Tuvikene, Lea; Viik, Malle; Nõges, Tiina

    2016-10-01

    Understanding of the true role of lakes in the global carbon cycle requires reliable estimates of dissolved organic carbon (DOC) and there is a strong need to develop remote sensing methods for mapping lake carbon content at larger regional and global scales. Part of DOC is optically inactive. Therefore, lake DOC content cannot be mapped directly. The objectives of the current study were to estimate the relationships of DOC and other water and environmental variables in order to find the best proxy for remote sensing mapping of lake DOC. The Boosted Regression Trees approach was used to clarify in which relative proportions different water and environmental variables determine DOC. In a studied large and shallow eutrophic lake the concentrations of DOC and coloured dissolved organic matter (CDOM) were rather high while the seasonal and interannual variability of DOC concentrations was small. The relationships between DOC and other water and environmental variables varied seasonally and interannually and it was challenging to find proxies for describing seasonal cycle of DOC. Chlorophyll a (Chl a), total suspended matter and Secchi depth were correlated with DOC and therefore are possible proxies for remote sensing of seasonal changes of DOC in ice free period, while for long term interannual changes transparency-related variables are relevant as DOC proxies. CDOM did not appear to be a good predictor of the seasonality of DOC concentration in Lake Võrtsjärv since the CDOM-DOC coupling varied seasonally. However, combining the data from Võrtsjärv with the published data from six other eutrophic lakes in the world showed that CDOM was the most powerful predictor of DOC and can be used in remote sensing of DOC concentrations in eutrophic lakes. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Confirmatory linkage study of hypochondroplasia

    Energy Technology Data Exchange (ETDEWEB)

    Hecht, J.T.; Herrera, C.; Greenhaw, G.A. [Univ. of Texas Medical School, Houston, TX (United States)] [and others

    1994-09-01

    Hypochondroplasia is an autosomal dominant form of disproportionate short stature disorder that has clinical and radiographic findings similar to but milder than achondroplasia. Based on these findings it has been suggested that achondroplasia and hypochondroplasia are allelic conditions. We and others have mapped the achondroplasia locus to telomeric region of chromosome 4. Tested linkage to 4p markers in 6 hypochondroplasia families and a maximum LOD score of 1.7 at {theta} = 0 was found for IUDA. Here we report the results of a linkage study in 4 multigenerational families with hypochondroplasia using 7 short tandem repeat markers (D4S127, D4S412, D4S43, D4S115, IUDA, D4S227, D4S169) from the short arm of chromosome 4. These families have been well characterized and show the typical clinical and radiographic features of hypochondroplasia. One family was Afro-American, one Hispanic and two were Caucasian. We found a maximum multipoint LOD score of 2.9 at D4S115. The results of this study provide confirmatory evidence that achondroplasia and hypochondroplasia map to the same chromosomal location and suggests that they are indeed allelic conditions.

  16. Trends of eutrophication in the Loire River (France)

    Science.gov (United States)

    Minaudo, Camille; Moatar, Florentina; Gassama, Nathalie; Curie, Florence

    2016-04-01

    The Loire River (France) was known to be sensible to eutrophication at the end of the 1970s, especially in its lower reaches with extreme phytoplankton growth (chlorophyll a concentration up to 250 μg L-1 in summer). During the 80s and 90s, the Loire estuary was often in state of anoxia in summer, as a result of the biodegradation of large quantities of labile organic matter. In this context, this work aimed at identifying clearly its eutrophication trajectories since the European environmental measures undertook in the early 1990s, and aimed at studying the physical and chemical causes and consequences of phytoplankton blooms. The long-term water quality time-series carried out by the national authorities allowed to identify the Loire River eutrophication trends since 1980. Since the extreme conditions in the early 1990s, phytoplankton developments in summer were divided 3-fold in the Loire River and in the main tributaries, synchronously with the generalized reduction 2-fold of bioavailable phosphorous. This was mostly attributable to the improvement of P treatment in the upstream waste water treatment plants. Thus, controlling and limiting P point sources greatly limited the magnitude of phytoplankton blooms (from 150 to 60 μg Chl. a L-1 between 1990 and 2012 in the lower Loire reaches). These trajectories highly changed the spatio-temporal dynamics of nutrients. Organic carbon (C-org) was not measured within the regular survey, however, based on some strong relationships between particulate C-org, suspended solids and pigments concentrations measured recently within a daily scale survey (2012-2014), C-org fluxes of the past could be reasonably assessed and it was estimated that 50% of the total C-org fluxes entering the estuarine zone in summer had autochthonous origins in the 80s and 90s against 20% during the period 2012-2014. Eutrophication has decreased in the freshwater system but keeps affecting the coastal zone, especially because algal species in

  17. Assessing ways to combat eutrophication in a Chinese drinking water reservoir using SWAT

    DEFF Research Database (Denmark)

    Nielsen, Anders; Trolle, Dennis; Me, W

    2013-01-01

    Across China, nutrient losses associated with agricultural production and domestic sewage have triggered eutrophication, and local managers are challenged to comply with drinking water quality requirements. Evidently, the improvement of water quality should be targeted holistically and encompass...... both point sources and surface activities within the watershed of a reservoir. We expanded the ordinary Soil Water Assessment Tool – (SWAT) with a widely used empirical equation to estimate total phosphorus (TP) concentrations in lakes and reservoirs. Subsequently, we examined the effects of changes...... in land and livestock management and sewage treatment on nutrient export and derived consequences for water quality in the Chinese subtropical Kaiping (Dashahe) drinking water reservoir (supplying 0.4 million people). The critical load of TP was estimated to 13.5 tonnes yr–1 in order to comply...

  18. An introduction to recombination and linkage analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mcpeek, M.S. [Univ. of Chicago, IL (United States)

    1996-12-31

    With a garden as his laboratory, Mendel was able to discern basic probabilistic laws of heredity. Although it first appeared as a baffling exception to one of Mendel`s principles, the phenomenon of variable linkage between characters was soon recognized to be a powerful tool in the process of chromosome mapping and location of genes of interest. In this introduction, we first describe Mendel`s work and the subsequent discovery of linkage. Next we describe the apparent cause of variable linkage, namely recombination, and we introduce linkage analysis. 33 refs., 1 fig., 2 tabs.

  19. Challenges in administrative data linkage for research

    Directory of Open Access Journals (Sweden)

    Katie Harron

    2017-12-01

    Full Text Available Linkage of population-based administrative data is a valuable tool for combining detailed individual-level information from different sources for research. While not a substitute for classical studies based on primary data collection, analyses of linked administrative data can answer questions that require large sample sizes or detailed data on hard-to-reach populations, and generate evidence with a high level of external validity and applicability for policy making. There are unique challenges in the appropriate research use of linked administrative data, for example with respect to bias from linkage errors where records cannot be linked or are linked together incorrectly. For confidentiality and other reasons, the separation of data linkage processes and analysis of linked data is generally regarded as best practice. However, the ‘black box’ of data linkage can make it difficult for researchers to judge the reliability of the resulting linked data for their required purposes. This article aims to provide an overview of challenges in linking administrative data for research. We aim to increase understanding of the implications of (i the data linkage environment and privacy preservation; (ii the linkage process itself (including data preparation, and deterministic and probabilistic linkage methods and (iii linkage quality and potential bias in linked data. We draw on examples from a number of countries to illustrate a range of approaches for data linkage in different contexts.

  20. Validation of an instrument to measure inter-organisational linkages in general practice

    Directory of Open Access Journals (Sweden)

    Cheryl Amoroso

    2007-11-01

    Full Text Available Purpose: Linkages between general medical practices and external services are important for high quality chronic disease care. The purpose of this research is to describe the development, evaluation and use of a brief tool that measures the comprehensiveness and quality of a general practice’s linkages with external providers for the management of patients with chronic disease. In this study, clinical linkages are defined as the communication, support, and referral arrangements between services for the care and assistance of patients with chronic disease. Methods: An interview to measure surgery-level (rather than individual clinician-level clinical linkages was developed, piloted, reviewed, and evaluated with 97 Australian general practices. Two validated survey instruments were posted to patients, and a survey of locally available services was developed and posted to participating Divisions of General Practice (support organisations. Hypotheses regarding internal validity, association with local services, and patient satisfaction were tested using factor analysis, logistic regression and multilevel regression models. Results: The resulting General Practice Clinical Linkages Interview (GP-CLI is a nine-item tool with three underlying factors: referral and advice linkages, shared care and care planning linkages, and community access and awareness linkages. Local availability of chronic disease services has no affect on the comprehensiveness of services with which practices link, however comprehensiveness of clinical linkages has an association with patient assessment of access, receptionist services, and of continuity of care in their general practice. Conclusions: The GP-CLI may be useful to researchers examining comparable health care systems for measuring the comprehensiveness and quality of linkages at a general practice-level with related services, possessing both internal and external validity. The tool can be used with large samples

  1. Robustness of linkage strategy that leads to large-scale cooperation.

    Science.gov (United States)

    Inaba, Misato; Takahashi, Nobuyuki; Ohtsuki, Hisashi

    2016-11-21

    One of the most well-known models to characterize cooperation among unrelated individuals is Social dilemma (SD). However there is no consensus about how to solve the SD by itself. Since SDs are often embedded in other social interactions, including indirect reciprocity games (IR), human can coordinate their behaviors across multiple games. Such coordination is called 'linkage'. Recently linkage has been considered as a promising solution to resolve SDs, since excluding SD defectors (i.e. those who defected in SD) from indirectly reciprocal relationships functions as a costless sanction. A previous study performed mathematical modeling and revealed that a linkage strategy, which cooperates in SD and engages in the Standing strategy in IR based on the recipients' behaviors in both SD and IR, was an ESS against a non-linkage strategy which defects in SD and engages in the Standing strategy in IR based on recipients' behaviors only in IR (Panchanathan and Boyd, 2004). In order to investigate the robustness of the linkage strategy, we devised a non-linkage strategy, which cooperates in SD but does not link two games. First, we conducted a mathematical analysis and demonstrated that the linkage strategy was not an ESS against cooperating non-linkage strategy. Second, we conducted a series of agent-based computer simulations to examine how the strategies perform in situations in which various types of errors can occur. Our results showed that the linkage strategy was an ESS only when there are implementation errors in SD. However, the equilibrium of the linkage strategy was unstable when there are perception errors. Since we know that humans are not free from perception errors in their social life, future studies will need to show how perception errors can be overcome in order to provide support for the conclusion that linkage is a plausible solution to SDs. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Ocean acidification: One potential driver of phosphorus eutrophication.

    Science.gov (United States)

    Ge, Changzi; Chai, Yanchao; Wang, Haiqing; Kan, Manman

    2017-02-15

    Harmful algal blooms which may be limited by phosphorus outbreak increases currently and ocean acidification worsens presently, which implies that ocean acidification might lead to phosphorus eutrophication. To verify the hypothesis, oxic sediments were exposed to seawater with different pH 30days. If pH was 8.1 and 7.7, the total phosphorus (TP) content in sediments was 1.52±0.50 and 1.29±0.40mg/g. The inorganic phosphorus (IP) content in sediments exposed to seawater with pH8.1 and 7.7 was 1.39±0.10 and 1.06±0.20mg/g, respectively. The exchangeable phosphorus (Ex-P) content in sediments was 4.40±0.45 and 2.82±0.15μg/g, if seawater pH was 8.1 and 7.7. Ex-P and IP contents in oxic sediments were reduced by ocean acidification significantly (pocean acidification was one potential facilitator of phosphorus eutrophication in oxic conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Phytoplankton and Eutrophication Degree Assessment of Baiyangdian Lake Wetland, China

    Science.gov (United States)

    Wang, Xing; Wang, Yu; Liu, Lusan; Shu, Jianmin; Zhu, Yanzhong; Zhou, Juan

    2013-01-01

    Eight typical sampling sites were chosen to investigate the phytoplankton community structure and to assess the eutrophication degree of Baiyangdian Lake in 2009. Our results showed that among the total 133 species identified, Cyanophyta, Chlorophyta, and Bacillariophyta dominated the phytoplankton community. In spring, Chlorophyta and Bacillariophyta were the dominant phyla, and the dominant species included Chlorella sp., Chroomonas acuta Uterm., and Microcystis incerta Lemm.; the density of the phytoplankton ranged from 496 × 104 to 6256 × 104 cells/L with an average of 2384 × 104 cells/L. However, Chlorophyta and Cyanophyta became the dominant phyla in summer, and the dominant species were Chlorella sp., Leptolyngbya valderiana Anagn., and Nephrocytium agardhianum Nageli.; the density of the phytoplankton varied from 318 × 104 to 4630 × 104 cells/L with an average of 1785 × 104 cells/L. The density of the phytoplankton has increased significantly compared to the previous investigations in 2005. The index of Carlson nutritional status (TSIM) and the dominant genus assessment indicated that the majority of Baiyangdian Lake was in eutrophic state. PMID:23983633

  4. Can Humic Water Discharge Counteract Eutrophication in Coastal Waters?

    Science.gov (United States)

    Andersson, Agneta; Jurgensone, Iveta; Rowe, Owen F.; Simonelli, Paolo; Bignert, Anders; Lundberg, Erik; Karlsson, Jan

    2013-01-01

    A common and established view is that increased inputs of nutrients to the sea, for example via river flooding, will cause eutrophication and phytoplankton blooms in coastal areas. We here show that this concept may be questioned in certain scenarios. Climate change has been predicted to cause increased inflow of freshwater to coastal areas in northern Europe. River waters in these areas are often brown from the presence of high concentrations of allochthonous dissolved organic carbon (humic carbon), in addition to nitrogen and phosphorus. In this study we investigated whether increased inputs of humic carbon can change the structure and production of the pelagic food web in the recipient seawater. In a mesocosm experiment unfiltered seawater from the northern Baltic Sea was fertilized with inorganic nutrients and humic carbon (CNP), and only with inorganic nutrients (NP). The system responded differently to the humic carbon addition. In NP treatments bacterial, phytoplankton and zooplankton production increased and the systems turned net autotrophic, whereas the CNP-treatment only bacterial and zooplankton production increased driving the system to net heterotrophy. The size-structure of the food web showed large variations in the different treatments. In the enriched NP treatments the phytoplankton community was dominated by filamentous >20 µm algae, while in the CNP treatments the phytoplankton was dominated by picocyanobacteria eutrophication in coastal waters, leading to a promotion of the microbial food web and other heterotrophic organisms, driving the recipient coastal waters to net-heterotrophy. PMID:23637807

  5. Environmental assessment of drainage water impacts on water quality and eutrophication level of Lake Idku, Egypt.

    Science.gov (United States)

    Ali, Elham M; Khairy, Hanan M

    2016-09-01

    Lake Idku, northern Egypt, receives large quantities of drainage water from four main discharging drains. Ecological and biological status of Lake Idku has been monitored during (autumn 2012 to summer 2013) to examine the lake water quality and eutrophication level in response to the quality as well as the source of the discharging water. Discrete water samples were collected from the lake body and the drains. Chemical analyses revealed an excessive nutrient load goes into the lake. A range of 1.4-10.6 mg nitrites/L was determined for drain waters, however a sudden increase was observed in lake and drain water samples of up to 84 and 74.5 mg/L, respectively. Reactive silicate ranged between 2.9 and 4.8 mg/L; while inorganic phosphate fluctuated between 0.2 and 0.43 mg/L. Transparency varied from 45 cm to 134 cm with better light conditions at drain sites. Biological results indicated a hyper-eutrophic status for the lake with a range of chlorophyll-a varied from a minimum of 39.9 μg/L (at Idku Drains) and a maximum of 104.2 μg/L (at El-Khairy drain). Phytoplankton community structure revealed higher abundance at lake sites compared with the drains. Maximum phytoplankton density was detected during summer with the dominance of Bacilariophyceae (e.g. Cyclotella meneghiniana, Cyclotella comate, Melosira varians) followed by Chlorophycean taxon (e.g. Scenedesmus dimorphus, S. bijuga and Crucigenia tetrapedia). Five indices were applied to evaluate the water quality of the lake. Diversity Index (DI) indicated slight to light pollution along all sites; while Sapropic Index (SI) indicated slight pollution with acceptable oxygen conditions and an availability of sensitive species. Palmer Index (PI) gave a strong evidence of high organic pollution at some sites in the lake, while Generic Diatom Index (GDI) revealed that levels of pollution varied from average to strong. Trophic Index (TI), suggest that there are an obvious signs of eutrophication in the lake

  6. Record Linkage Paral.lel

    OpenAIRE

    Guisado Gámez, Joan

    2009-01-01

    Els objectius estan classificats de més generals (més exteriors), a més específics (més interiors). 1 Accelerar el procés de Record Linkage mitjançant tècniques de computació paral·lela. 1.1 Aprendre a utilitzar MPI. 1.2 Implementar una paral·lelització distribuïda. 1.3 Utilitzar ordinadors comuns, de sobretaula. 1.4 Implementar una paral·lelització de memoria compartida a nivell de node. 1.5 Dur a terme una implementació conscient de les restriccions de memòria. 1.6 U...

  7. Community stoichiometry in a changing world: combined effects of warming and eutrophication on phytoplankton dynamics

    NARCIS (Netherlands)

    Senerpont Domis, de L.N.; Waal, van de D.B.; Helmsing, N.R.; Donk, van E.; Mooij, W.M.

    2014-01-01

    The current changes in our climate will likely have far-reaching consequences for aquatic ecosystems. These changes in the climate, however, do not act alone, and are often accompanied by additional stressors such as eutrophication. Both global warming and eutrophication have been shown to affect

  8. Microbial Community Structure in Relation to Water Quality in a Eutrophic Gulf of Mexico Estuary

    Science.gov (United States)

    Weeks Bay is a shallow, microtidal, eutrophic sub-estuary of Mobile Bay, AL. High watershed nutrient inputs to the estuary contribute to a eutrophic condition characterized by frequent summertime diel-cycling hypoxia and dissolved oxygen (DO) oversaturation. Spatial and seasonal ...

  9. Community stoichiometry in a changing world: combined effects of warming and eutrophication on phytoplankton dynamics

    NARCIS (Netherlands)

    De Senerpont Domis, L.N.; Van de Waal, D.B.; Helmsing, N.R.; Van Donk, E.; Mooij, W.M.

    2014-01-01

    The current changes in our climate will likely have far reaching consequences for aquatic ecosystems. These changes in the climate, however, do not act alone and are often accompanied by additional stressors such as eutrophication. Both global warming and eutrophication have been shown to affect the

  10. Ascendency as an ecological indicator: a case study of estuarine pulse eutrophication

    Science.gov (United States)

    Patrício, J.; Ulanowicz, R.; Pardal, M. A.; Marques, J. C.

    2004-05-01

    Increasingly, management agencies require that the remediation of eutrophic waters be addressed at the level of the whole ecosystem. One whole-system approach to quantify ecosystems is called ecological network analysis. Ascendency theory, the branch of the field that deals with the quantification of whole-system status, specifically addresses the definition of eutrophication. This definition has been applied to data taken over a gradient of eutrophication. Three separate areas were observed: a non-eutrophic area (with Zostera noltii meadows), an intermediate eutrophic area ( Z. noltii absent and macroalgae abundant at times) and a strongly eutrophic area (where Enteromorpha spp. blooms occur with regularity). Pulse eutrophication was considered as the major driving force behind a gradual shift in primary producers from a community dominated by rooted macrophytes ( Z. noltii) to a community dominated by green macroalgae. The measures associated with the intermediate eutrophic region turned out not to be intermediate to those at the gradient extremes. The most likely explanation appears to be the highly unstable nature of this area. Conditions along the spatial gradient are discussed as representing various stages in the temporal evolution of the system, and analysed in the framework of the Intermediate Disturbance Hypothesis, Bifurcation, Chaos, and Catastrophe theories.

  11. “Marine eutrophication is the process of enrich- ment of marine ...

    African Journals Online (AJOL)

    spamer

    “Marine eutrophication is the process of enrich- ment of marine systems with plant nutrients that stim- ulate primary production, and, in its most serious manifestation, leads to visible algal blooms and at times massive growth of macrophytes” (Vollenweider. 1992, p. 3). Marine eutrophication has become a.

  12. Linkage of familial essential tremor to chromosome 5q35.

    Science.gov (United States)

    Hicks, James E; Konidari, Ioanna; Scott, Burton L; Stajich, Jeffrey M; Ashley-Koch, Allison E; Gilbert, John R; Scott, William K

    2016-07-01

    Essential tremor is a neurological condition characterized by tremor during voluntary movement. To date, 3 loci linked to familial essential tremor have been identified. We examined 48 essential tremor patients in 5 large essential tremor pedigrees in our data set for genetic linkage using an Affymetrix Axiom array. Linkage analysis was performed using an affecteds-only dominant model in SIMWALK2. To incorporate all genotype information, GERMLINE was used to identify genome segments shared identical-by-descent in pairs of affecteds. Exome sequencing was performed in pedigrees showing evidence of linkage. For one family, chromosomes 5 and 18 showed genome-wide significant linkage to essential tremor. Shared segment analysis excluded the 18p11 candidate region and reduced the 5q35 region by 1 megabase. Exome sequencing did not identify a potential causative variant in this region. A locus on chromosome 5 is linked to essential tremor. Further research is needed to identify a causative variant. © 2016 International Parkinson and Movement Disorder Society. © 2016 International Parkinson and Movement Disorder Society.

  13. Top-down control as important as nutrient enrichment for eutrophication effects in North Atlantic coastal ecosystems

    NARCIS (Netherlands)

    Ostman, Orjan; Eklof, Johan; Eriksson, Britas Klemens; Olsson, Jens; Moksnes, Per-Olav; Bergstrom, Ulf

    Seagrass and seaweed habitats constitute hotspots for diversity and ecosystem services in coastal ecosystems. These habitats are subject to anthropogenic pressures, of which eutrophication is one major stressor. Eutrophication favours fast-growing ephemeral algae over perennial macroalgae and

  14. Bioavailable phosphorus (P) reduction is less than mobile P immobilization in lake sediment for eutrophication control by inactivating agents

    NARCIS (Netherlands)

    Wang, Changhui; He, Rui; Wu, Yu; Lürling, Miquel; Cai, Haiyuan; Jiang, He-Long; Liu, Xin

    2017-01-01

    Abstract Phosphorus (P) immobilization by inactivating agents in the sediment of eutrophic lakes to reduce immediately available P in lake water is often crucial for mitigating nuisance eutrophication symptoms, such as cyanobacterial blooms. Macrophytes and phytoplankton, however, can directly

  15. Larval growth in the dominant polychaete Polydora ciliata is food-limited in a eutrophic Danish estuary (Isefjord)

    DEFF Research Database (Denmark)

    Pedersen, Troels Møller; Almeda, Rodrigo; Fotel, Frank Lech

    2010-01-01

    Food limitation in larval growth of the spionid polychaete Polydora ciliata was examined in a typical eutrophic estuary, Isefjord, in Denmark. In the field, food availability and the energetic requirements of the P. ciliata larval population were measured during 2 different periods in 2004 and 2007...... that together cover the productive part of the year for plankton. In the laboratory, specific growth rates (µ) of larvae reared on natural food suspensions (~0.10 d–1) were always lower than those of larvae reared on phytoplankton-enriched food suspensions (100% retention efficiency for Rhodomonas salina; ~0...

  16. Eutrophication potential of lakes: an integrated analysis of trophic state, morphometry, land occupation, and land use.

    Science.gov (United States)

    Silvino, R F; Barbosa, F A R

    2015-08-01

    Despite being inside a protected area, Lake Sumidouro has been impacted by the anthropogenic occupation of the surrounding area since the 1970's, compromising the ecological integrity of the lake and the sustainable use of natural resources. This study examined the current trophic classification of the lake and developed methods for improving it through an integrated analysis of morphometric and limnological parameters, land use and land occupation in the watershed, and eutrophication potential. Data for the limnological parameters, land use and land occupation, and morphometric characteristics of Lake Sumidouro were collected in the rainy and dry seasons of 2009 and 2010. Depending on the trophic classification system used, Lake Sumidouro is classified as oligotrophic to hypereutrophic. In our study, the highest concentration of nutrients occurred in the rainy season, indicating that high nutrient inputs played an important role during this period. Areas of anthropogenic occupation comprised approximately 62.9% of the total area of the watershed, with pasture and urban settlement as the main types of land use. The influent total phosphorus load was estimated to be 15,824.3 kg/year. To maintain mesotrophic conditions, this load must be reduced by 29.4%. By comparing the isolated use of trophic state indices, this study demonstrated that comparing the trophic state classification with morphometric analyses, land use and land occupation types in the watershed, and potential phosphorus load provided better information to guide management actions for restoration and conservation. Furthermore, this approach also allowed for evaluating the vulnerability of the environment to the eutrophication process.

  17. Eutrophication potential of lakes: an integrated analysis of trophic state, morphometry, land occupation, and land use

    Directory of Open Access Journals (Sweden)

    RF Silvino

    Full Text Available AbstractDespite being inside a protected area, Lake Sumidouro has been impacted by the anthropogenic occupation of the surrounding area since the 1970’s, compromising the ecological integrity of the lake and the sustainable use of natural resources. This study examined the current trophic classification of the lake and developed methods for improving it through an integrated analysis of morphometric and limnological parameters, land use and land occupation in the watershed, and eutrophication potential. Data for the limnological parameters, land use and land occupation, and morphometric characteristics of Lake Sumidouro were collected in the rainy and dry seasons of 2009 and 2010. Depending on the trophic classification system used, Lake Sumidouro is classified as oligotrophic to hypereutrophic. In our study, the highest concentration of nutrients occurred in the rainy season, indicating that high nutrient inputs played an important role during this period. Areas of anthropogenic occupation comprised approximately 62.9% of the total area of the watershed, with pasture and urban settlement as the main types of land use. The influent total phosphorus load was estimated to be 15,824.3 kg/year. To maintain mesotrophic conditions, this load must be reduced by 29.4%. By comparing the isolated use of trophic state indices, this study demonstrated that comparing the trophic state classification with morphometric analyses, land use and land occupation types in the watershed, and potential phosphorus load provided better information to guide management actions for restoration and conservation. Furthermore, this approach also allowed for evaluating the vulnerability of the environment to the eutrophication process.

  18. Our evolving conceptual model of the coastal eutrophication problem

    Science.gov (United States)

    Cloern, James E.

    2001-01-01

    A primary focus of coastal science during the past 3 decades has been the question: How does anthropogenic nutrient enrichment cause change in the structure or function of nearshore coastal ecosystems? This theme of environmental science is recent, so our conceptual model of the coastal eutrophication problem continues to change rapidly. In this review, I suggest that the early (Phase I) conceptual model was strongly influenced by limnologists, who began intense study of lake eutrophication by the 1960s. The Phase I model emphasized changing nutrient input as a signal, and responses to that signal as increased phytoplankton biomass and primary production, decomposition of phytoplankton-derived organic matter, and enhanced depletion of oxygen from bottom waters. Coastal research in recent decades has identified key differences in the responses of lakes and coastal-estuarine ecosystems to nutrient enrichment. The contemporary (Phase II) conceptual model reflects those differences and includes explicit recognition of (1) system-specific attributes that act as a filter to modulate the responses to enrichment (leading to large differences among estuarine-coastal systems in their sensitivity to nutrient enrichment); and (2) a complex suite of direct and indirect responses including linked changes in: water transparency, distribution of vascular plants and biomass of macroalgae, sediment biogeochemistry and nutrient cycling, nutrient ratios and their regulation of phytoplankton community composition, frequency of toxic/harmful algal blooms, habitat quality for metazoans, reproduction/growth/survival of pelagic and benthic invertebrates, and subtle changes such as shifts in the seasonality of ecosystem functions. Each aspect of the Phase II model is illustrated here with examples from coastal ecosystems around the world. In the last section of this review I present one vision of the next (Phase III) stage in the evolution of our conceptual model, organized around 5

  19. Reducing Phosphorus to Curb Lake Eutrophication is a Success.

    Science.gov (United States)

    Schindler, David W; Carpenter, Stephen R; Chapra, Steven C; Hecky, Robert E; Orihel, Diane M

    2016-09-06

    As human populations increase and land-use intensifies, toxic and unsightly nuisance blooms of algae are becoming larger and more frequent in freshwater lakes. In most cases, the blooms are predominantly blue-green algae (Cyanobacteria), which are favored by low ratios of nitrogen to phosphorus. In the past half century, aquatic scientists have devoted much effort to understanding the causes of such blooms and how they can be prevented or reduced. Here we review the evidence, finding that numerous long-term studies of lake ecosystems in Europe and North America show that controlling algal blooms and other symptoms of eutrophication depends on reducing inputs of a single nutrient: phosphorus. In contrast, small-scale experiments of short duration, where nutrients are added rather than removed, often give spurious and confusing results that bear little relevance to solving the problem of cyanobacteria blooms in lakes.

  20. Alcian blue-stained particles in a eutrophic lake

    DEFF Research Database (Denmark)

    Worm, J.; Søndergaard, Morten

    1998-01-01

    We used a neutral solution of Alcian Blue to stain transparent particles in eutrophic Lake Frederiksborg Slotss0, Denmark. Alcian Blue-stained particles (ABSP) appeared to be similar to the so-called transparent exopolymer particles (TEP) identified with an acidic solution of Alcian Blue. Our...... results on the abundance, size distribution and bacterial colonization of ABSP therefore reflect general patterns of TEP. The abundance of ABSP in the size range 3-162 urn and retained by 3 um pore size filters averaged 3.6 ± 2.49 x 10s ml"1 (± SD), which is among the highest concentrations reported...... for comparable size spectra of TEP. On average, 35 % of ABSP (by number) were colonized by bacteria and 8.6 x 105 bacteria ml"1 lake water were attached to ABSP, which corresponds to 7% of the total bacterial abundance....

  1. Optical Changes in a Eutrophic Estuary During Reduced Nutrient Loadings

    DEFF Research Database (Denmark)

    Pedersen, Troels Møller; Sand-Jensen, Kaj; Markager, Stiig

    2014-01-01

    Loss of water clarity is one of the consequences of coastal eutrophication. Efforts have therefore been made to reduce external nutrient loadings of coastal waters. This paper documents improvements to water clarity between 1985 and 2008–2009 at four stations in the microtidal estuary Roskilde...... Fjord and find significant relationships to freshwater nutrient loadings. The paper then investigates to which extent changes in phytoplankton biomass (chlorophyll a (Chl a)), non-algal particulate organic matter (POM*), and residual attenuation in the water (K b), respectively, can account...... to 74 % in 1985 to 78 to 85 % in 2008–2009. Overall, efforts to reduce nutrient loading and improve water clarity appeared to have had a larger impact on POM* than on Chl a and colored dissolved organic matter concentrations in the estuary, which can account for the decrease in the scatter...

  2. From fish to jellyfish in the eutrophicated Limfjorden (Denmark)

    DEFF Research Database (Denmark)

    Riisgård, Hans Ulrik; Andersen, Per; Hoffmann, Erik

    2012-01-01

    years where the fish have been replaced by an increasing number of especially the moon jellyfish, Aurelia aurita, which mainly preys on zooplankton. Next, we evaluate the ecological consequences of the present high number of jellyfish, based on data from recent years’ research on the abundance...... the historical development of nutrient overloading and subsequent oxygen depletion in near-bottom water, and how the annual landings of edible bottom-dwelling fish species (plaice, flounder, eel and others) caught in Limfjorden have decreased from about 2,500 t in the early 1920s to only about 20 t in recent...... a substantial part of the zooplankton biomass. Marine environmental management programmes should be aware of the increasing importance of both indigenous and new invasive jellyfish species that may show mass occurrence in especially eutrophicated and overfished areas...

  3. Can humic water discharge counteract eutrophication in coastal waters?

    Directory of Open Access Journals (Sweden)

    Agneta Andersson

    Full Text Available A common and established view is that increased inputs of nutrients to the sea, for example via river flooding, will cause eutrophication and phytoplankton blooms in coastal areas. We here show that this concept may be questioned in certain scenarios. Climate change has been predicted to cause increased inflow of freshwater to coastal areas in northern Europe. River waters in these areas are often brown from the presence of high concentrations of allochthonous dissolved organic carbon (humic carbon, in addition to nitrogen and phosphorus. In this study we investigated whether increased inputs of humic carbon can change the structure and production of the pelagic food web in the recipient seawater. In a mesocosm experiment unfiltered seawater from the northern Baltic Sea was fertilized with inorganic nutrients and humic carbon (CNP, and only with inorganic nutrients (NP. The system responded differently to the humic carbon addition. In NP treatments bacterial, phytoplankton and zooplankton production increased and the systems turned net autotrophic, whereas the CNP-treatment only bacterial and zooplankton production increased driving the system to net heterotrophy. The size-structure of the food web showed large variations in the different treatments. In the enriched NP treatments the phytoplankton community was dominated by filamentous >20 µm algae, while in the CNP treatments the phytoplankton was dominated by picocyanobacteria <5 µm. Our results suggest that climate change scenarios, resulting in increased humic-rich river inflow, may counteract eutrophication in coastal waters, leading to a promotion of the microbial food web and other heterotrophic organisms, driving the recipient coastal waters to net-heterotrophy.

  4. Eutrophic urban ponds suffer from cyanobacterial blooms: Dutch examples.

    Science.gov (United States)

    Waajen, Guido W A M; Faassen, Elisabeth J; Lürling, Miquel

    2014-01-01

    Ponds play an important role in urban areas. However, cyanobacterial blooms counteract the societal need for a good water quality and pose serious health risks for citizens and pets. To provide insight into the extent and possible causes of cyanobacterial problems in urban ponds, we conducted a survey on cyanobacterial blooms and studied three ponds in detail. Among 3,500 urban ponds in the urbanized Dutch province of North Brabant, 125 showed cyanobacterial blooms in the period 2009-2012. This covered 79% of all locations registered for cyanobacterial blooms, despite the fact that urban ponds comprise only 11% of the area of surface water in North Brabant. Dominant bloom-forming genera in urban ponds were Microcystis, Anabaena and Planktothrix. In the three ponds selected for further study, the microcystin concentration of the water peaked at 77 μg l(-1) and in scums at 64,000 μg l(-1), which is considered highly toxic. Microcystin-RR and microcystin-LR were the most prevalent variants in these waters and in scums. Cyanobacterial chlorophyll-a peaked in August with concentrations up to 962 μg l(-1) outside of scums. The ponds were highly eutrophic with mean total phosphorus concentrations between 0.16 and 0.44 mg l(-1), and the sediments were rich in potential releasable phosphorus. High fish stocks dominated by carp lead to bioturbation, which also favours blooms. As urban ponds in North Brabant, and likely in other regions, regularly suffer from cyanobacterial blooms and citizens may easily have contact with the water and may ingest cyanobacterial material during recreational activities, particularly swimming, control of health risk is of importance. Monitoring of cyanobacteria and cyanobacterial toxins in urban ponds is a first step to control health risks. Mitigation strategies should focus on external sources of eutrophication and consider the effect of sediment P release and bioturbation by fish.

  5. Coastal eutrophication in Europe caused by production of energy crops.

    Science.gov (United States)

    van Wijnen, Jikke; Ivens, Wilfried P M F; Kroeze, Carolien; Löhr, Ansje J

    2015-04-01

    In Europe, the use of biodiesel may increase rapidly in the coming decades as a result of policies aiming to increase the use of renewable fuels. Therefore, the production of biofuels from energy crops is expected to increase as well as the use of fertilisers to grow these crops. Since fertilisers are an important cause of eutrophication, the use of biodiesel may have an effect on the water quality in rivers and coastal seas. In this study we explored the possible effects of increased biodiesel use on coastal eutrophication in European seas in the year 2050. To this end, we defined a number of illustrative scenarios in which the biodiesel production increases to about 10-30% of the current diesel use. The scenarios differ with respect to the assumptions on where the energy crops are cultivated: either on land that is currently used for agriculture, or on land used for other purposes. We analysed these scenarios with the Global NEWS (Nutrient Export from WaterSheds) model. We used an existing Millennium Ecosystem Assessment Scenario for 2050, Global Orchestration (GO2050), as a baseline. In this baseline scenario the amount of nitrogen (N) and phosphorus (P) exported by European rivers to coastal seas decreases between 2000 and 2050 as a result of environmental and agricultural policies. In our scenarios with increased biodiesel production the river export of N and P increases between 2000 and 2050, indicating that energy crop production may more than counterbalance this decrease. Largest increases in nutrient export were calculated for the Mediterranean Sea and the Black Sea. Differences in nutrient export among river basins are large. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Can humic water discharge counteract eutrophication in coastal waters?

    Science.gov (United States)

    Andersson, Agneta; Jurgensone, Iveta; Rowe, Owen F; Simonelli, Paolo; Bignert, Anders; Lundberg, Erik; Karlsson, Jan

    2013-01-01

    A common and established view is that increased inputs of nutrients to the sea, for example via river flooding, will cause eutrophication and phytoplankton blooms in coastal areas. We here show that this concept may be questioned in certain scenarios. Climate change has been predicted to cause increased inflow of freshwater to coastal areas in northern Europe. River waters in these areas are often brown from the presence of high concentrations of allochthonous dissolved organic carbon (humic carbon), in addition to nitrogen and phosphorus. In this study we investigated whether increased inputs of humic carbon can change the structure and production of the pelagic food web in the recipient seawater. In a mesocosm experiment unfiltered seawater from the northern Baltic Sea was fertilized with inorganic nutrients and humic carbon (CNP), and only with inorganic nutrients (NP). The system responded differently to the humic carbon addition. In NP treatments bacterial, phytoplankton and zooplankton production increased and the systems turned net autotrophic, whereas the CNP-treatment only bacterial and zooplankton production increased driving the system to net heterotrophy. The size-structure of the food web showed large variations in the different treatments. In the enriched NP treatments the phytoplankton community was dominated by filamentous >20 µm algae, while in the CNP treatments the phytoplankton was dominated by picocyanobacteria <5 µm. Our results suggest that climate change scenarios, resulting in increased humic-rich river inflow, may counteract eutrophication in coastal waters, leading to a promotion of the microbial food web and other heterotrophic organisms, driving the recipient coastal waters to net-heterotrophy.

  7. Dynamics of particulate phosphorus in a shallow eutrophic lake

    Energy Technology Data Exchange (ETDEWEB)

    Shinohara, Ryuichiro, E-mail: r-shino@nies.go.jp [National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan); Imai, Akio; Kohzu, Ayato; Tomioka, Noriko [National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan); Furusato, Eiichi [Graduate School of Science and Engineering, Saitama University, 255 Shimo-okubo, Sakura-ku, Saitama 338-8570 (Japan); Satou, Takayuki; Sano, Tomoharu; Komatsu, Kazuhiro; Miura, Shingo; Shimotori, Koichi [National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506 (Japan)

    2016-09-01

    We tested the hypothesis that in shallow, eutrophic Lake Kasumigaura, the concentration of particulate phosphorus (PP) is controlled by biogenic P (P in living or dead phytoplankton and bacterial cells), rather than by resuspension of inorganic P in sediment. Increases in wind velocity and turbidity were associated with bottom shear stress exceeding the critical value for the lake (τ{sub c} = 0.15 N m{sup −2}); this increased turbidity was due to sediment resuspension. However, concentrations of PP; HCl-extractable, reactive P in PP (P-rP); and HCl-extractable, non-reactive P in PP (P-nrP) were not correlated with wind velocity (PP vs. wind velocity: r = 0.40, p > 0.05). Rather, the P-nrP concentration accounted for approximately 79% of PP, and the concentrations of PP, P-rP, and P-nrP were correlated with the particulate organic carbon (POC) concentration (POC vs. PP: r = 0.90, p < 0.01; POC vs. P-rP: r = 0.82, p < 0.01; POC vs. P-nrP: r = 0.86, p < 0.01). In our {sup 31}P nuclear magnetic resonance spectroscopy results, mononucleotides accounted for the largest proportion among the detected P compound classes. In addition, concentrations of mononucleotides, orthophosphate, and pyrophosphate were significantly higher in samples with high POC concentrations, whereas the DNA-P concentration was not. These results suggest that biogenic P affects PP concentrations more strongly than does sediment resuspension, and the production of biogenic P creates a pool of mononucleotides, a class of easily degradable P, even in shallow, eutrophic Lake Kasumigaura. - Highlights: • Biogenic P affected the PP concentration more than did sediment resuspension. • PP correlated with particulate organic carbon concentration but not wind velocity. • Mononucleotides accounted for the largest P compound class of organic P in PP.

  8. The National Eutrophication Survey: lake characteristics and historical nutrient concentrations

    Science.gov (United States)

    Stachelek, Joseph; Ford, Chanse; Kincaid, Dustin; King, Katelyn; Miller, Heather; Nagelkirk, Ryan

    2018-01-01

    Historical ecological surveys serve as a baseline and provide context for contemporary research, yet many of these records are not preserved in a way that ensures their long-term usability. The National Eutrophication Survey (NES) database is currently only available as scans of the original reports (PDF files) with no embedded character information. This limits its searchability, machine readability, and the ability of current and future scientists to systematically evaluate its contents. The NES data were collected by the US Environmental Protection Agency between 1972 and 1975 as part of an effort to investigate eutrophication in freshwater lakes and reservoirs. Although several studies have manually transcribed small portions of the database in support of specific studies, there have been no systematic attempts to transcribe and preserve the database in its entirety. Here we use a combination of automated optical character recognition and manual quality assurance procedures to make these data available for analysis. The performance of the optical character recognition protocol was found to be linked to variation in the quality (clarity) of the original documents. For each of the four archival scanned reports, our quality assurance protocol found an error rate between 5.9 and 17 %. The goal of our approach was to strike a balance between efficiency and data quality by combining entry of data by hand with digital transcription technologies. The finished database contains information on the physical characteristics, hydrology, and water quality of about 800 lakes in the contiguous US (Stachelek et al.(2017), https://doi.org/10.5063/F1639MVD). Ultimately, this database could be combined with more recent studies to generate meta-analyses of water quality trends and spatial variation across the continental US.

  9. Opportunities for longitudinal data linkage in Scotland.

    Science.gov (United States)

    Hagger-Johnson, Gareth

    2016-08-01

    Scotland has existing data resources which are competitive internationally and available to researchers from elsewhere. The Scottish Informatics and Linkage Collaboration (SILC) was recently launched, allowing data sets to be linked within and between sectors (e.g. health to non-health). The purpose of this review article is to introduce and define key terms in data linkage, to describe the emerging data linkage resources available in Scotland and to describe the opportunities available in Scotland to researchers internationally. The review is aimed at researchers internationally who are interested in data linkage using Scottish data resources. The review makes particular reference to longitudinal health data but emphasises that linkage to non-health data allows research questions to be considered that were previously not answerable. The review is focused on longitudinal data resources (e.g. cohort studies and repeated measures designs), since they are usually the focus of data linkage research. The review concludes that any intended data linkage for research should be driven by a clear research question. The infrastructure already available and the launch of SILC will accelerate research in Scotland and generate new research questions that previously could not be considered. © The Author(s) 2015.

  10. Analysis of linkage and linkage disequilibrium for eight X-STR markers.

    Science.gov (United States)

    Tillmar, Andreas O; Mostad, Petter; Egeland, Thore; Lindblom, Bertil; Holmlund, Gunilla; Montelius, Kerstin

    2008-12-01

    X-chromosomal short tandem repeats (X-STR) have proven to be informative and useful in complex relationship testing. The main feature of X-STR markers, compared to autosomal forensic markers, is that all loci are located on the same chromosome. Thus, linkage and linkage disequilibrium may occur. The aim of this work was to study population genetic parameters of eight X-STR markers, located in four linkage groups. We present haplotype frequencies, based on 718 Swedish males, for the four linkage groups included in the Argus X-8 kit. Forensic efficiency parameters have been calculated as well as the allelic association between the tested markers for detection of linkage disequilibrium. To study the occurrences of recombination between the loci, both Swedish and Somali families were typed. A mathematical model for the estimation of recombination frequencies is presented and applied on the family samples. Our study showed that the tested markers all have highly informative forensic values and that there is a significant degree of linkage disequilibrium between the STR markers within the four linkage groups. Furthermore, based on the tested families, we also demonstrated that two of the linkage groups are partially linked. A consequence of these findings is that both linkage and linkage disequilibrium should be accounted for when producing likelihood ratios in relationship testing with X-STR markers.

  11. Linkage mapping methods applied to the COGA data set: presentation Group 4 of Genetic Analysis Workshop 14.

    Science.gov (United States)

    Daw, E Warwick; Doan, Betty Q; Elston, Robert C

    2005-01-01

    Presentation Group 4 participants analyzed the Collaborative Study on the Genetics of Alcoholism data provided for Genetic Analysis Workshop 14. This group examined various aspects of linkage analysis and related issues. Seven papers included linkage analyses, while the eighth calculated identity-by-descent (IBD) probabilities. Six papers analyzed linkage to an alcoholism phenotype: ALDX1 (four papers), ALDX2 (one paper), or a combination both (one paper). Methods used included Bayesian variable selection coupled with Haseman-Elston regression, recursive partitioning to identify phenotype and covariate groupings that interact with evidence for linkage, nonparametric linkage regression modeling, affected sib-pair linkage analysis with discordant sib-pair controls, simulation-based homozygosity mapping in a single pedigree, and application of a propensity score to collapse covariates in a general conditional logistic model. Alcoholism linkage was found with > or =2 of these approaches on chromosomes 2, 4, 6, 7, 9, 14, and 21. The remaining linkage paper compared the utility of several single-nucleotide polymorphism (SNP) and microsatellite marker maps for Monte Carlo Markov chain combined oligogenic segregation and linkage analysis, and analyzed one of the electrophysiological endophenotypes, ttth1, on chromosome 7. Linkage was found with all marker sets. The last paper compared the multipoint IBD information content of several SNP sets and the microsatellite set, and found that while all SNP sets examined contained more information than the microsatellite set, most of the information contained in the SNP sets was captured by a subset of the SNP markers with approximately 1-cM marker spacing. From these papers, we highlight three points: a 1-cM SNP map seems to capture most of the linkage information, so denser maps do not appear necessary; careful and appropriate use of covariates can aid linkage analysis; and sources of increased gene-sharing between relatives

  12. Long-term temporal and spatial trends in eutrophication status of the Baltic Sea

    DEFF Research Database (Denmark)

    Andersen, Jesper; Carstensen, Jacob; Conley, Daniel J.

    2017-01-01

    report on the temporal and spatial trends of eutrophication status for the open Baltic Sea over a 112-year period using the HELCOM Eutrophication Assessment Tool (HEAT 3.0). Further, we analyse variation in the confidence of the eutrophication status assessment based on a systematic quantitative approach...... to reductions in the scope of monitoring programs. Our study sets a baseline for implementation of the ecosystem-based management strategies and policies currently in place including the EU Marine Strategy Framework Directives and the HELCOM Baltic Sea Action Plan. Key...

  13. A feasible method for linkage studies avoiding clerical review: linkage of the national HIV/AIDS surveillance databases with the National Death Index in Australia.

    Science.gov (United States)

    Nakhaee, Fatemeh; McDonald, Ann; Black, Deborah; Law, Matthew

    2007-08-01

    To assess the sensitivity and specificity of linkage of HIV/AIDS diagnoses in Australia to the National Death Index (NDI). An aggregated file containing 19,772 matched HIV/AIDS diagnoses reported to the national HIV/AIDS databases from 1980 to 30 June 2004 was linked to the NDI using probabilistic linkage methods based on the namecode, date of birth, and sex as identifiers. Based on the 6,900 HIV/AIDS known deaths reported by 1 January 2003 and 1,455 known non-deaths with an active follow-up beyond 1 January 2003, the different combinations of weights assigned to matched pairs were examined to obtain maximum sensitivity and specificity. The trade-off between sensitivity and specificity was used to obtain an optimal linkage. The optimal linkage was found to link 5,658 of the 6,900 HIV/AIDS known deaths (a sensitivity of 82%), and 116 false positives of the 1,455 known not deaths (specificity of 92%). Causes of deaths were recorded for 86.5% of deaths that were linked to the NDI. This is a feasible method for conducting linkage studies if both the identifying deaths and non-deaths are available. The relatively poor sensitivity could be due to limited identifiers available for linkage on the HIV/AIDS databases.

  14. Drift of the sialyl-linkage specific recognition of the sialidase of influenza B virus isolates.

    Science.gov (United States)

    Xu, G; Suzuki, T; Hanagata, G; Deya, E; Kiso, M; Hasegawa, A; Suzuki, Y

    1993-03-01

    Sialyl-linkage specificity of the sialidase of influenza B viruses isolated in different years from 1940 through 1990 (B/Lee/40,B/Setagaya/3/56,B/Tokyo/7/66,B/Kagoshima/1/68, B/Gifu/2/73, B/Kanagawa/3/76, B/Ibaraki/2/85, B/Yamagata/16/88, and B/Bangkok/163/90) was studied with N-acetylneuraminyl (alpha 2-3)- and (alpha 2-6)-lactoses, GM3 gangliosides containing the same sialyl-oligosaccharide sequences as sialyllactose, and also with type I and type II lacto-series gangliosides carrying Neu5Ac alpha 2-3Gal and NeuAc alpha 2-6Gal linkages as substrates. From an examination of up to nine strains, the sialidases of all viruses preferentially hydrolyze substrates with Neu5Ac alpha 2-3Gal linkage rather than the Neu5Ac alpha 2-6Gal linkage. It was found that the sialidase activity toward Neu5Ac alpha 2-6Gal linkage relative to Neu5Ac alpha 2-3Gal linkage is increased in later strains, whether sialyllactose or ganglioside is used as the substrate. These results suggested that the sialidase of influenza B virus isolates has shown a drift in linkage specificity which correlates with the year of isolation.

  15. Linkage disequilibrium in wild mice.

    Directory of Open Access Journals (Sweden)

    Cathy C Laurie

    2007-08-01

    Full Text Available Crosses between laboratory strains of mice provide a powerful way of detecting quantitative trait loci for complex traits related to human disease. Hundreds of these loci have been detected, but only a small number of the underlying causative genes have been identified. The main difficulty is the extensive linkage disequilibrium (LD in intercross progeny and the slow process of fine-scale mapping by traditional methods. Recently, new approaches have been introduced, such as association studies with inbred lines and multigenerational crosses. These approaches are very useful for interval reduction, but generally do not provide single-gene resolution because of strong LD extending over one to several megabases. Here, we investigate the genetic structure of a natural population of mice in Arizona to determine its suitability for fine-scale LD mapping and association studies. There are three main findings: (1 Arizona mice have a high level of genetic variation, which includes a large fraction of the sequence variation present in classical strains of laboratory mice; (2 they show clear evidence of local inbreeding but appear to lack stable population structure across the study area; and (3 LD decays with distance at a rate similar to human populations, which is considerably more rapid than in laboratory populations of mice. Strong associations in Arizona mice are limited primarily to markers less than 100 kb apart, which provides the possibility of fine-scale association mapping at the level of one or a few genes. Although other considerations, such as sample size requirements and marker discovery, are serious issues in the implementation of association studies, the genetic variation and LD results indicate that wild mice could provide a useful tool for identifying genes that cause variation in complex traits.

  16. Identifying marker typing incompatibilities in linkage analysis

    Energy Technology Data Exchange (ETDEWEB)

    Stringham, H.M.; Boehnke, M. [Univ. of Michigan, Ann Arbor, MI (United States)

    1996-10-01

    A common problem encountered in linkage analyses is that execution of the computer program is halted because of genotypes in the data that are inconsistent with Mendelian inheritance. Such inconsistencies may arise because of pedigree errors or errors in typing. In some cases, the source of the inconsistencies is easily identified by examining the pedigree. In others, the error is not obvious, and substantial time and effort are required to identify the responsible genotypes. We have developed two methods for automatically identifying those individuals whose genotypes are most likely the cause of the inconsistencies. First, we calculate the posterior probability of genotyping error for each member of the pedigree, given the marker data on all pedigree members and allowing anyone in the pedigree to have an error. Second, we identify those individuals whose genotypes could be solely responsible for the inconsistency in the pedigree. We illustrate these methods with two examples: one a pedigree error, the second a genotyping error. These methods have been implemented as a module of the pedigree analysis program package MENDEL. 9 refs., 2 figs., 2 tabs.

  17. Resource linkages and sustainable development

    Science.gov (United States)

    Anouti, Yahya

    Historically, fossil fuel consumers in most developing hydrocarbon-rich countries have enjoyed retail prices at a discount from international benchmarks. Governments of these countries consider the subsidy transfer to be a means for sharing the wealth from their resource endowment. These subsidies create negative economic, environmental, and social distortions, which can only increase over time with a fast growing, young, and rich population. The pressure to phase out these subsidies has been mounting over the last years. At the same time, policy makers in resource-rich developing countries are keen to obtain the greatest benefits for their economies from the extraction of their exhaustible resources. To this end, they are deploying local content policies with the aim of increasing the economic linkages from extracting their resources. Against this background, this dissertation's three essays evaluate (1) the global impact of rationalizing transport fuel prices, (2) how resource-rich countries can achieve the objectives behind fuel subsidies more efficiently through direct cash transfers, and (3) the economic tradeoffs from deploying local content policies and the presence of an optimal path. We begin by reviewing the literature and building the case for rationalizing transport fuel prices to reflect their direct costs (production), indirect costs (road maintenance) and negative externalities (climate change, local pollutants, traffic accidents and congestion). To do so, we increase the scope of the economic literature by presenting an algorithm to evaluate the rationalized prices in different countries. Then, we apply this algorithm to quantify the rationalized prices across 123 countries in a partial equilibrium setting. Finally, we present the first comprehensive measure of the impact of rationalizing fuel prices on the global demand for gasoline and diesel, environmental emissions, government revenues, and consumers' welfare. By rationalizing transport fuel

  18. Linkage studies in primary open angle glaucoma

    Energy Technology Data Exchange (ETDEWEB)

    Avramopoulos, D.; Grigoriadu, M. [Institute of Child Health, Athens (Greece); Kitsos, G. [Univ. Eye Clinic of Ioannina (Greece)] [and others

    1994-09-01

    Glaucoma is a leading cause of blindness worldwide. The majority of glaucoma is associated with an open, normal appearing anterior chamber angle and is termed primary open angle glaucoma (POAG, MIM 137760). It is characterized by elevated intraocular pressure and onset in middle age or later. A subset of POAG with juvenile onset has recently been linked to chromosome 1q in two families with autosomal dominant inheritance. Eleven pedigrees with autosomal dominant POG (non-juvenile-onset) have been identified in Epirus, Greece. In the present study DNA samples have been collected from 50 individuals from one large pedigree, including 12 affected individuals. Preliminary results of linkage analysis with chromosome 1 microsatellites using the computer program package LINKAGE Version 5.1 showed no linkage with the markers previously linked to juvenile-onset POAG. Further linkage analysis is being pursued, and the results will be presented.

  19. Missing Linkages in California's Landscape [ds420

    Data.gov (United States)

    California Department of Resources — The critical need for conserving landscape linkages first came to the forefront of conservation thinking in California in November 2000, when a statewide interagency...

  20. When to conduct probabilistic linkage vs. deterministic linkage? A simulation study

    National Research Council Canada - National Science Library

    Zhu, Ying; Matsuyama, Yutaka; Ohashi, Yasuo; Setoguchi, Soko

    2015-01-01

    ... to variations in data quality, implementation of linkage methodology and validation method. The simulation study aimed to understand data characteristics that affect the performance of probabilistic vs...

  1. Eutrophication problems in the Western Harbour of Alexandria, Egypt

    Directory of Open Access Journals (Sweden)

    Mohamed A. Okbah

    2004-03-01

    Full Text Available Eutrophication-related problems in the Western Harbour of Alexandria were studied monthly from April 1999 to March 2000. Variation in salinity appeared to be the key to all changes in water quality and plankton abundance in the harbour. Both at the surface and near the bottom the salinity was lower (annual average: 35.1 and 38.3 PSU respectively than in the open sea (39 PSU. Dissolved oxygen levels indicated poor aeration conditions along the water column (2.3-3.98 mg l-1. Average pH values were approximately similar in the two layers (8.1 and 8 respectively but exhibited different ranges of variations. Nutrient salts varied widely, often occurring in high concentrations, with ranges of 0.12-5.7 and 0.06-2.6 µM at the surface and the bottom respectively for phosphate, 0.21-20.46 and 0.25-18.12 µM for nitrate, 0.29-3.3 and 0.23-1.66 µM for nitrite, 0.56-57.46 and 2.32-43.73 µM for ammonia and 0.3-36.3 and 0.48-38.4 µM for silicate. As a result of nutrient enrichment, phytoplankton growth was very intensive, reflected by an abnormally high concentration of chlorophyll a (annual average: 33.82 µg l-1. At the same time the death of large numbers of phytoplankton cells could be inferred from the relatively large amount of phaeopigment (annual average: 10.39 µg l-1. The high levels of nutrient salts and phytoplankton biomass together serve as a good indicator of high eutrophication levels in the Western Harbour throughout the year. These conditions clearly affected the zooplankton stock, which varied between 5.8-93.6 × 103 indiv. m-3, although for most of the time values remained at a low level (annual average: 26 728 indiv. m-3.

  2. Fault linkage and continental breakup

    Science.gov (United States)

    Cresswell, Derren; Lymer, Gaël; Reston, Tim; Stevenson, Carl; Bull, Jonathan; Sawyer, Dale; Morgan, Julia

    2017-04-01

    The magma-poor rifted margin off the west coast of Galicia (NW Spain) has provided some of the key observations in the development of models describing the final stages of rifting and continental breakup. In 2013, we collected a 68 x 20 km 3D seismic survey across the Galicia margin, NE Atlantic. Processing through to 3D Pre-stack Time Migration (12.5 m bin-size) and 3D depth conversion reveals the key structures, including an underlying detachment fault (the S detachment), and the intra-block and inter-block faults. These data reveal multiple phases of faulting, which overlap spatially and temporally, have thinned the crust to between zero and a few km thickness, producing 'basement windows' where crustal basement has been completely pulled apart and sediments lie directly on the mantle. Two approximately N-S trending fault systems are observed: 1) a margin proximal system of two linked faults that are the upward extension (breakaway faults) of the S; in the south they form one surface that splays northward to form two faults with an intervening fault block. These faults were thus demonstrably active at one time rather than sequentially. 2) An oceanward relay structure that shows clear along strike linkage. Faults within the relay trend NE-SW and heavily dissect the basement. The main block bounding faults can be traced from the S detachment through the basement into, and heavily deforming, the syn-rift sediments where they die out, suggesting that the faults propagated up from the S detachment surface. Analysis of the fault heaves and associated maps at different structural levels show complementary fault systems. The pattern of faulting suggests a variation in main tectonic transport direction moving oceanward. This might be interpreted as a temporal change during sequential faulting, however the transfer of extension between faults and the lateral variability of fault blocks suggests that many of the faults across the 3D volume were active at least in part

  3. Spatial differentiated effect assessment for aquatic eutrophication in Life Cycle Assessment.

    NARCIS (Netherlands)

    Penailillo, Reinaldo

    2005-01-01

    The conventional evaluation of aquatic eutrophication in Life Cycle Assessment (LCA) expresses the contribution of nitrogen and/or phosphorus emissions to biomass production in terms of the equivalent emission of a reference substance. This assessment doe

  4. Spatial Differentiated Effect Assessment for Aquatic Eutrophication in Life Cycle Assessment

    OpenAIRE

    Penailillo, R.

    2005-01-01

    The conventional evaluation of aquatic eutrophication in Life Cycle Assessment (LCA) expresses the contribution of nitrogen and/or phosphorus emissions to biomass production in terms of the equivalent emission of a reference substance. This assessment doe

  5. Integrated water quality, emergy and economic evaluation of three bioremediation treatment systems for eutrophic water

    Science.gov (United States)

    This study was targeted at finding one or more environmentally efficient, economically feasible and ecologically sustainable bioremediation treatment modes for eutrophic water. Three biological species, i.e. water spinach (Ipomoea aquatica), loach (Misgurus anguillicaudatus) and ...

  6. The effects of groundwater discharge, mowing, and eutrophication on fen vegetation evaluated over half a century

    NARCIS (Netherlands)

    Belle, J. van; Barendregt, Arie; Schot, P.P.; Wassen, M.J.

    2006-01-01

    Questions: Were continued groundwater discharge and mowing regimes sufficient for vegetation preservation from 1944 to 1993? Which has a stronger effect on vegetation development; groundwater discharge or mowing? What is the role of surface water eutrophication as driver of vegetation

  7. How well do ecosystem indicators communicate the effects of anthropogenic eutrophication?

    NARCIS (Netherlands)

    McQuatters-Gollop, A.; Gilbert, A.J.; Mee, L.; Vermaat, J.E.; Artioli, Y.; Humborg, C.; Wulff, F.

    2009-01-01

    Anthropogenic eutrophication affects the Mediterranean, Black, North and Baltic Seas to various extents. Responses to nutrient loading and methods of monitoring relevant indicators vary regionally, hindering interpretation of ecosystem state changes and preventing a straightforward pan-European

  8. Eutrophication and cyanobacteria in South Africa’s standing water bodies: A view from space

    CSIR Research Space (South Africa)

    Matthews, MW

    2015-05-01

    Full Text Available Satellite remote sensing can make a significant contribution to monitoring water quality in South African standing water bodies. Eutrophication, defined as enrichment by nutrients, and toxin-producing cyanobacteria (blue-green algae) blooms pose a...

  9. Determinants of the microbial community structure of eutrophic, hyporheic river sediments polluted with chlorinated aliphatic hydrocarbons

    NARCIS (Netherlands)

    Hamonts, K.; Ryngaert, A.; Smidt, H.; Springael, D.; Dejonghe, W.

    2014-01-01

    Chlorinated aliphatic hydrocarbons (CAHs) often discharge into rivers as contaminated groundwater baseflow. As biotransformation of CAHs in the impacted river sediments might be an effective remediation strategy, we investigated the determinants of the microbial community structure of eutrophic,

  10. Is nutrient contamination of groundwater causing eutrophication of groundwater-fed meadows?

    NARCIS (Netherlands)

    Pieterse, N.M.; Olde Venterink, H.; Schot, P.P.; Verkroost, A.W.M.

    2005-01-01

    There is an ongoing debate as to whether nutrient contamination of groundwater under agricultural fields may cause nutrient-enrichment and subsequent eutrophication in discharge areas. Often, there is only circumstantial evidence to support this supposition (proximity of agricultural fields,

  11. EUTROPHICATION OF WATER RESERVOIRS AND ROLE OF MACROPHYTES IN THIS PROCESS

    Directory of Open Access Journals (Sweden)

    Joanna Jadwiga Sender

    2017-06-01

    Full Text Available The paper presents the problem related with the process of eutrophication, with special emphasis on dam reservoirs. Eutrophication is a global process, threatening the water ecosystem on every continent. It often leads to their degradation. Particularly vulnerable to eutrophication are artificial reservoirs which are dam reservoirs. This paper describes the mechanisms of eutrophication. We also pointed to the importance of aquatic plants in the process of water purification, as well as the possibility of multilateral use. Recently, in the world and in Poland there is a tendency to pay attention to the natural or semi-natural method of water purification (including constructed wetland. On the one hand, the presence of macrophytes in water bodies is a guarantor of good ecological status, on the other hand, the undeniable aesthetic value.

  12. Analysis of Mathematics and Sustainability in an Impulsive Eutrophication Controlling System

    Directory of Open Access Journals (Sweden)

    Hengguo Yu

    2013-01-01

    quite accurate to describe the interaction effect of some critical factors (fishermen catch and releasing small fry, etc., which enables a systematic and logical procedure for fitting eutrophication mathematical system to real monitoring data and experiment data. Mathematical theoretical works have been pursuing the investigation of two threshold functions of some critical parameters under the condition of all species persistence, which can in turn provide a theoretical basis for the numerical simulation. Using numerical simulation works, we mainly focus on how to choose the best value of some critical parameters to ensure the sustainability of the eutrophication system so that the eutrophication removal process can be well developed with maximizing economic benefit. These results may be further extended to provide a basis for simulating the algal bloom in the laboratory and understanding the application of some impulsive controlling models about eutrophication removal problems.

  13. Genetics and linkage of aldrin resistance in the German cockroach, Blattella germanica (L.)*

    Science.gov (United States)

    McDonald, I. C.; Ross, M. H.; Cochran, D. G.

    1969-01-01

    The inheritance mechanism and linkage association of cyclodiene resistance were studied in 2 cyclodiene-resistant strains of the German cockroach. The resistant strains were crossed to each other, to an unmarked susceptible strain, and to 6 susceptible marker strains. The progeny from succeeding generations were tested for resistance to aldrin using a dipping method or a time-exposure method, and were examined for markers in linkage tests. The results show that cyclodiene resistance (R-Cyclo) is inherited as a simple autosomal semidominant trait which is allelic in the 2 resistant strains. Linkage studies indicate that R-Cyclo is independent of linkage groups II—VI, but is linked with the group VII trait curly wing at a distance of 3.4±1.0-6.2±1.4. PMID:5307235

  14. Disentangling the effects of a century of eutrophication and climate warming on freshwater lake fish assemblages.

    Science.gov (United States)

    Jacobson, Peter C; Hansen, Gretchen J A; Bethke, Bethany J; Cross, Timothy K

    2017-01-01

    Eutrophication and climate warming are profoundly affecting fish in many freshwater lakes. Understanding the specific effects of these stressors is critical for development of effective adaptation and remediation strategies for conserving fish populations in a changing environment. Ecological niche models that incorporated the individual effects of nutrient concentration and climate were developed for 25 species of fish sampled in standard gillnet surveys from 1,577 Minnesota lakes. Lake phosphorus concentrations and climates were hindcasted to a pre-disturbance period of 1896-1925 using existing land use models and historical temperature data. Then historical fish assemblages were reconstructed using the ecological niche models. Substantial changes were noted when reconstructed fish assemblages were compared to those from the contemporary period (1981-2010). Disentangling the sometimes opposing, sometimes compounding, effects of eutrophication and climate warming was critical for understanding changes in fish assemblages. Reconstructed abundances of eutrophication-tolerant, warmwater taxa increased in prairie lakes that experienced significant eutrophication and climate warming. Eutrophication-intolerant, warmwater taxa abundance increased in forest lakes where primarily climate warming was the stressor. Coolwater fish declined in abundance in both ecoregions. Large changes in modeled abundance occurred when the effects of both climate and eutrophication operated in the same direction for some species. Conversely, the effects of climate warming and eutrophication operated in opposing directions for other species and dampened net changes in abundance. Quantifying the specific effects of climate and eutrophication will allow water resource managers to better understand how lakes have changed and provide expectations for sustainable fish assemblages in the future.

  15. Long-term temporal and spatial trends in eutrophication status of the Baltic Sea.

    Science.gov (United States)

    Andersen, Jesper H; Carstensen, Jacob; Conley, Daniel J; Dromph, Karsten; Fleming-Lehtinen, Vivi; Gustafsson, Bo G; Josefson, Alf B; Norkko, Alf; Villnäs, Anna; Murray, Ciarán

    2017-02-01

    Much of the Baltic Sea is currently classified as 'affected by eutrophication'. The causes for this are twofold. First, current levels of nutrient inputs (nitrogen and phosphorus) from human activities exceed the natural processing capacity with an accumulation of nutrients in the Baltic Sea over the last 50-100 years. Secondly, the Baltic Sea is naturally susceptible to nutrient enrichment due to a combination of long retention times and stratification restricting ventilation of deep waters. Here, based on a unique data set collated from research activities and long-term monitoring programs, we report on the temporal and spatial trends of eutrophication status for the open Baltic Sea over a 112-year period using the HELCOM Eutrophication Assessment Tool (HEAT 3.0). Further, we analyse variation in the confidence of the eutrophication status assessment based on a systematic quantitative approach using coefficients of variation in the observations. The classifications in our assessment indicate that the first signs of eutrophication emerged in the mid-1950s and the central parts of the Baltic Sea changed from being unaffected by eutrophication to being affected. We document improvements in eutrophication status that are direct consequences of long-term efforts to reduce the inputs of nutrients. The reductions in both nitrogen and phosphorus loads have led to large-scale alleviation of eutrophication and to a healthier Baltic Sea. Reduced confidence in our assessment is seen more recently due to reductions in the scope of monitoring programs. Our study sets a baseline for implementation of the ecosystem-based management strategies and policies currently in place including the EU Marine Strategy Framework Directives and the HELCOM Baltic Sea Action Plan. © 2015 The Authors. Biological Reviews published by John Wiley & Sons Ltd on behalf of Cambridge Philosophical Society.

  16. [Response of Phytoplankton Functional Groups to Eutrophication in Summer at Xiaoguan Reservoir].

    Science.gov (United States)

    Li, Lei; Li, Qiu-hua; Jiao, Shu-lin; Li, Yue; Xiao, Jing; Deng, Long; Sun, Rong-guo; Gao, Yong-chun; Luo, Lan

    2015-12-01

    Hydrology and Water Resources Bureau of Guizhou Province, Guiyang 550002, China) Abstract: In order to explore the distribution characteristics of phytoplankton functional groups, eutrophication characteristics and response of phytoplankton functional groups to eutrophication in Xiaoguan Reservoir, phytoplankton and water samples were taken once a week from 25th July 2014 to 27th September 2014. The results showed that there were 22 phytoplankton functional groups, groups S1, D, J, B, G, MP, L₀, SN, X1, Y, Xph, F, T and W1 were comparatively common functional groups, Wherein, S1, D and J were the dominant functional groups. Weekly dynamics of phytoplankton functional groups were: S1-->S1-->S1-->S1-->S1--S1-->S1-->J/D/S1-->Sl1- >/1D. group Sl1dominated over other groups, the cell abundance of S1 appeared two peaks at week 5 and week 7 respectively, but there was a slump at week 8, and rose again at last, compared to two peaks before, the cell abundance had dropped from 10⁸cells · L⁻¹ to 10⁷cells · L⁻¹ Water flush caused by discharge gate opening artificially was the main reason. Based on the three methods of eutrophication evaluation, the water was in moderately eutrophic and eutrophic states in Xiaoguan Reservoir in the summer of 2014. Multivariate analysis (RDA) indicated transparency was the main factor affecting the distribution of phytoplankton functional groups, and nutrients were no longer the limiting factor. The study suggested that phytoplankton functional groups could make a good response to eutrophication: groups S1 and J adapted to the turbid eutrophic water bodies, D adapted to shallow turbid waters and was sensitive to nutrient depletion. Also, common functional groups like G, X1, WW1 F etc. mostly adapted to eutrophic water bodies.

  17. Indirect facilitation promotes macrophyte survival and growth in freshwater ecosystems threatened by eutrophication

    OpenAIRE

    Le Bagousse-Pinguet, Yoann; Liancourt, Pierre; Gross, Nicolas; Straile, Dietmar

    2012-01-01

    1. Eutrophication is a major threat for freshwater ecosystems. Submerged aquatic plants (macrophytes) can maintain clear water conditions in eutrophic lakes by competing with phytoplankton for light and nutrients. The interactions between macrophytes and phytoplankton may lead to indirect facilitation among plants and the maintenance of high macrophyte diversities in eutrophicconditions. Nonetheless, the role of indirect facilitation in promoting macrophyte-dominated clear water states under ...

  18. Enhanced effects of biotic interactions on predicting multispecies spatial distribution of submerged macrophytes after eutrophication

    OpenAIRE

    Song, Kun; Cui, Yichong; Zhang, Xijin; Pan, Yingji; Xu, Junli; Xu, Kaiqin; Da, Liangjun

    2017-01-01

    Abstract Water eutrophication creates unfavorable environmental conditions for submerged macrophytes. In these situations, biotic interactions may be particularly important for explaining and predicting the submerged macrophytes occurrence. Here, we evaluate the roles of biotic interactions in predicting spatial occurrence of submerged macrophytes in 1959 and 2009 for Dianshan Lake in eastern China, which became eutrophic since the 1980s. For the four common species occurred in 1959 and 2009,...

  19. Disentangling the effects of a century of eutrophication and climate warming on freshwater lake fish assemblages.

    Directory of Open Access Journals (Sweden)

    Peter C Jacobson

    Full Text Available Eutrophication and climate warming are profoundly affecting fish in many freshwater lakes. Understanding the specific effects of these stressors is critical for development of effective adaptation and remediation strategies for conserving fish populations in a changing environment. Ecological niche models that incorporated the individual effects of nutrient concentration and climate were developed for 25 species of fish sampled in standard gillnet surveys from 1,577 Minnesota lakes. Lake phosphorus concentrations and climates were hindcasted to a pre-disturbance period of 1896-1925 using existing land use models and historical temperature data. Then historical fish assemblages were reconstructed using the ecological niche models. Substantial changes were noted when reconstructed fish assemblages were compared to those from the contemporary period (1981-2010. Disentangling the sometimes opposing, sometimes compounding, effects of eutrophication and climate warming was critical for understanding changes in fish assemblages. Reconstructed abundances of eutrophication-tolerant, warmwater taxa increased in prairie lakes that experienced significant eutrophication and climate warming. Eutrophication-intolerant, warmwater taxa abundance increased in forest lakes where primarily climate warming was the stressor. Coolwater fish declined in abundance in both ecoregions. Large changes in modeled abundance occurred when the effects of both climate and eutrophication operated in the same direction for some species. Conversely, the effects of climate warming and eutrophication operated in opposing directions for other species and dampened net changes in abundance. Quantifying the specific effects of climate and eutrophication will allow water resource managers to better understand how lakes have changed and provide expectations for sustainable fish assemblages in the future.

  20. Comparing linkage designs based on land facets to linkage designs based on focal species.

    Science.gov (United States)

    Brost, Brian M; Beier, Paul

    2012-01-01

    Least-cost modeling for focal species is the most widely used method for designing conservation corridors and linkages. However, these designs depend on today's land covers, which will be altered by climate change. We recently proposed an alternative approach based on land facets (recurring landscape units of relatively uniform topography and soils). The rationale is that corridors with high continuity of individual land facets will facilitate movement of species associated with each facet today and in the future. Conservation practitioners might like to know whether a linkage design based on land facets is likely to provide continuity of modeled breeding habitat for species needing connectivity today, and whether a linkage for focal species provides continuity and interspersion of land facets. To address these questions, we compared linkages designed for focal species and land facets in three landscapes in Arizona, USA. We used two variables to measure linkage utility, namely distances between patches of modeled breeding habitat for 5-16 focal species in each linkage, and resistance profiles for focal species and land facets between patches connected by the linkage. Compared to focal species designs, linkage designs based on land facets provided as much or more modeled habitat connectivity for 25 of 28 species-landscape combinations, failing only for the three species with the most narrowly distributed habitat. Compared to land facets designs, focal species linkages provided lower connectivity for about half the land facets in two landscapes. In areas where a focal species approach to linkage design is not possible, our results suggest that conservation practitioners may be able to implement a land facets approach with some confidence that the linkage design would serve most potential focal species. In areas where focal species designs are possible, we recommend using the land facet approach to complement, rather than replace, focal species approaches.

  1. A linkage map with RFLP and isozyme markers for almond.

    Science.gov (United States)

    Viruel, M A; Messeguer, R; de Vicente, M C; Garcia-Mas, J; Puigdomènech, P; Vargas, F; Arús, P

    1995-11-01

    Inheritance and linkage studies were conducted with seven isozyme genes and 120 RFLPs in the F1 progeny of a cross between almond cultivars 'Ferragnes' and 'Tuono'. RFLPs were detected using 57 genomic and 43 cDNA almond clones. Eight of the cDNA probes corresponded to known genes (extensin, prunin (2), α-tubulin, endopolygalacturonase, oleosin, actin depolymerizing factor and phosphoglyceromutase). Single-copy clones were found more frequently in the cDNA (65%) than in the genomic libraries (26%). Two maps were elaborated, one with the 93 loci heterozygous in 'Ferragnes' and another with the 69 loci heterozygous in 'Tuono'. Thirty-five loci were heterozygous in both parents and were used as bridges between both maps. Most of the segregations (91%) were of the 1∶1 or 1∶1∶1∶1 types, and data were analyzed as if they derived from two backcross populations. Eight linkage groups covering 393 cM in 'Ferragnes' and 394 in 'Tuono' were found for each map. None of the loci examined in either map was found to be unlinked. Distorted segregation ratios were mainly concentrated in two linkage groups of the 'Ferragnes' map.

  2. Eutrophication Increases Phytoplankton Methylmercury Concentrations in a Coastal Sea-A Baltic Sea Case Study.

    Science.gov (United States)

    Soerensen, Anne L; Schartup, Amina T; Gustafsson, Erik; Gustafsson, Bo G; Undeman, Emma; Björn, Erik

    2016-11-01

    Eutrophication is expanding worldwide, but its implication for production and bioaccumulation of neurotoxic monomethylmercury (MeHg) is unknown. We developed a mercury (Hg) biogeochemical model for the Baltic Sea and used it to investigate the impact of eutrophication on phytoplankton MeHg concentrations. For model evaluation, we measured total methylated Hg (MeHg T ) in the Baltic Sea and found low concentrations (39 ± 16 fM) above the halocline and high concentrations in anoxic waters (1249 ± 369 fM). To close the Baltic Sea MeHg T budget, we inferred an average normoxic water column Hg II methylation rate constant of 2 × 10 -4 d -1 . We used the model to compare Baltic Sea's present-day (2005-2014) eutrophic state to an oligo/mesotrophic scenario. Eutrophication increases primary production and export of organic matter and associated Hg to the sediment effectively removing Hg from the active biogeochemical cycle; this results in a 27% lower present-day water column Hg reservoir. However, increase in organic matter production and remineralization stimulates microbial Hg methylation resulting in a seasonal increase in both water and phytoplankton MeHg reservoirs above the halocline. Previous studies of systems dominated by external MeHg sources or benthic production found eutrophication to decrease MeHg levels in plankton. This Baltic Sea study shows that in systems with MeHg production in the normoxic water column eutrophication can increase phytoplankton MeHg content.

  3. Trachelomonas (Euglenophyta) from a eutrophic reservoir in Central Mexico.

    Science.gov (United States)

    Solórzano, Gloria Garduño; Martinez, Maria Guadalupe Oliva; Vazquez, Alfonso Lugo; Garfias, Maria Berenit Mendoza; Zuñiga, Rafael Emiliano Quintanar; Conforti, Visitacion

    2011-07-01

    This study provides valuable information on the ultrastructure and environmental conditions of the Trachelomonas Ehr. (Euglenophyceae) genus in the Guadalupe Dam, a eutrophic reservoir located in the suburbs of Mexico City, which receives a considerable volume of wastewaters. Specimens were collected at surface level between November 2005 and May 2006. Using LM and SEM twelve taxa from phytoplankton were identified of which, 9 are new records for Mexico. The reservoir is warm monomictic, with basic pH values (7.4-10.1), a high concentration of chlorophyll a(18-101 microg l(-1), a permanent anoxic bottom, specific conductivity (K25) of 205 to 290 microS cm(-1), N-NO3, 0.19-1.2 mg l(-1) and P-PO4 0.22-1.6 mg l(-1). Water temperature was 15.6-23.0 degrees C. Most of the Trachelomonas species were found during the dry season, when concentrations of organic matter, nitrogen and phosphorus as well as the temperature were the highest. Higher species richness was also associated with the warmer months. This research contributes to increase our knowledge on Trachelomonas in Mexico and constitutes the first detailed description of lorica ultrastructure of 12 taxa that grow in a body of water with high concentration of nutrients and a moderate amount of mineral contents.

  4. Retrieval of phycocyanin concentration in the eutrophic Taihu Lake

    Science.gov (United States)

    Wang, Jing; Shi, Runhe; Gao, Wei

    2014-10-01

    Phycocyanin (PC) in the blue-green algae is usually used to detect the quantity of the blue-green algae, and it has a special absorption at 620nm waveband. Taihu Lake has become severely turbid and eutrophic in recent years. However, the accuracy of empirical models varies highly. Therefore, it is very useful to find a model which can retrieve PC concentration in a good accuracy. In this work, four models (i.e. single band model, the radio model, the first-derivative model, the three-band model and empirical ratio model) were developed based on remote sending reflectance and measured PC concentration in Taihu Lake in May, 2010 to retrieve PC concentration and then to find out which one is the best. The results show that the 2nd order polynomial models generally had a better performance than the line models. The three-band model was the most optimal model because it had the highest values of R2 and the lowest values of RMSE.

  5. Eutrophication endpoints for large rivers in Ohio, USA.

    Science.gov (United States)

    Miltner, Robert J

    2018-01-04

    Relationships between biological and enrichment indicators were explored to demarcate hallmarks of enrichment that can be used in managing eutrophication in large rivers. Biological indicators were sensitive to the measured range of enrichment and generally showed linear responses. However, fish biotic integrity scores, 24-h ranges in dissolved oxygen, and biological oxygen demand all showed strong nonlinear responses coinciding with sestonic chlorophyll concentrations in the range of 20-50 μg/l. Hallmarks of overt overenrichment were defined as sestonic chlorophyll ≥ 100 μg/l, 5-day biological oxygen demand ≥ 6.0 mg/l, and 24-h range in dissolved oxygen ≥ 9.0 mg/l. Acceptable levels were defined as chlorophyll < 30 μg/l, 5-day biological oxygen demand < 2.5 mg/l, and 24-h dissolved oxygen range < 7.0 mg/l. Relationships between nutrient concentrations and sestonic chlorophyll were weak, mainly due to high ambient levels of nutrients. However, total phosphorus concentrations averaged lower at sites showing less overt signs of enrichment, suggesting 130 μg/l total phosphorus as a management target for presently overenriched waters.

  6. Can microcystins affect zooplankton structure community in tropical eutrophic reservoirs?

    Directory of Open Access Journals (Sweden)

    T. A. S. V. Paes

    Full Text Available Abstract The aim of our study was to assess whether cyanotoxins (microcystins can affect the composition of the zooplankton community, leading to domination of microzooplankton forms (protozoans and rotifers. Temporal variations in concentrations of microcystins and zooplankton biomass were analyzed in three eutrophic reservoirs in the semi-arid northeast region of Brazil. The concentration of microcystins in water proved to be correlated with the cyanobacterial biovolume, indicating the contributions from colonial forms such as Microcystis in the production of cyanotoxins. At the community level, the total biomass of zooplankton was not correlated with the concentration of microcystin (r2 = 0.00; P > 0.001, but in a population-level analysis, the biomass of rotifers and cladocerans showed a weak positive correlation. Cyclopoid copepods, which are considered to be relatively inefficient in ingesting cyanobacteria, were negatively correlated (r2 = – 0.01; P > 0.01 with the concentration of cyanotoxins. Surprisingly, the biomass of calanoid copepods was positively correlated with the microcystin concentration (r2 = 0.44; P > 0.001. The results indicate that allelopathic control mechanisms (negative effects of microcystin on zooplankton biomass do not seem to substantially affect the composition of mesozooplankton, which showed a constant and high biomass compared to the microzooplankton (rotifers. These results may be important to better understand the trophic interactions between zooplankton and cyanobacteria and the potential effects of allelopathic compounds on zooplankton.

  7. Genome scan for linkage to Gilles de la Tourette syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Barr, C.L.; Livingston, J.; Williamson, R. [and others

    1994-09-01

    Gilles de la Tourette Syndrome (TS) is a familial, neuropsychiatric disorder characterized by chronic, intermittent motor and vocal tics. In addition to tics, affected individuals frequently display symptoms such as attention-deficit hyperactivity disorder and/or obsessive compulsive disorder. Genetic analyses of family data have suggested that susceptibility to the disorder is most likely due to a single genetic locus with a dominant mode of transmission and reduced penetrance. In the search for genetic linkage for TS, we have collected well-characterized pedigrees with multiple affected individuals on whom extensive diagnostic evaluations have been done. The first stage of our study is to scan the genome systematically using a panel of uniformly spaced (10 to 20 cM), highly polymorphic, microsatellite markers on 5 families segregating TS. To date, 290 markers have been typed and 3,660 non-overlapping cM of the genome have been excluded for possible linkage under the assumption of genetic homogeneity. Because of the possibility of locus heterogeneity overall summed exclusion is not considered tantamount to absolute exclusion of a disease locus in that region. The results from each family are carefully evaluated and a positive lod score in a single family is followed up by typing closely linked markers. Linkage to TS was examined by two-point analysis using the following genetic model: single autosomal dominant gene with gene frequency .003 and maximum penetrance of .99. An age-of-onset correction is included using a linear function increasing from age 2 years to 21 years. A small rate of phenocopies is also incorporated into the model. Only individuals with TS or CMT according to DSM III-R criteria were regarded as affected for the purposes of this summary. Additional markers are being tested to provide coverage at 5 cM intervals. Moreover, we are currently analyzing the data non-parametrically using the Affected-Pedigree-Member Method of linkage analysis.

  8. Magnitude, spatial scale and optimization of ecosystem services from a nutrient extraction mussel farm in the eutrophic Skive Fjord, Denmark

    DEFF Research Database (Denmark)

    Nielsen, Pernille; Cranford, P. J.; Maar, M.

    2016-01-01

    Suspended mussel aquaculture has been proposed as a possible mechanism by which to remove excess nutrients from eutrophic marine areas. In this study, seasonal mussel growth and water clarification (through seston and phytoplankton depletion) were studied at a commercial-scale nutrient extractive...... mussel farm in a highly eu - trophic Danish fjord. Spatial variations in mussel biomass were examined throughout the year and no significant differences were detected within the farm. Food depletion by mussels was examined at spatial scales ranging from individuals to the entire farm and surrounding area....... Phytoplankton depletion on the scale of individual mussel loops, determined using the siphon mimic approach, indicated between 27 and 44% depletion of chlorophyll a (chl a). Farm-scale depletion was detected and visualized based on intensive 3D spatial surveys of the distribution of chl a and total suspended...

  9. Lake eutrophication and environmental change: A viability framework for resilience, vulnerability and adaptive capacity

    Science.gov (United States)

    Mathias, Jean-Denis; Rougé, Charles; Deffuant, Guillaume

    2013-04-01

    We present a simple stochastic model of lake eutrophication to demonstrate how the mathematical framework of viability theory fosters operational definitions of resilience, vulnerability and adaptive capacity, and then helps understand which response one should bring to environmental changes. The model represents the phosphorus dynamics, given that high concentrations trigger a regime change from oligotrophic to eutrophic, and causes ecological but also economic losses, for instance from tourism. Phosphorus comes from agricultural inputs upstream of the lake, and we will consider a stochastic input. We consider the system made of both the lake and its upstream region, and explore how to maintain the desirable ecological and economic properties of this system. In the viability framework, we translate these desirable properties into state constraints, then examine how, given the dynamics of the model and the available policy options, the properties can be kept. The set of states for which there exists a policy to keep the properties is called the viability kernel. We extend this framework to both major perturbations and long-term environmental changes. In our model, since the phosphorus inputs and outputs from the lake depend on rainfall, we will focus on extreme rainfall events and long-term changes in the rainfall regime. They can be described as changes in the state of the system, and may displace it outside the viability kernel. Its response can then be described using the concepts of resilience, vulnerability and adaptive capacity. Resilience is the capacity to recover by getting back to the viability kernel where the dynamics keep the system safe, and in this work we assume it to be the first objective of management. Computed for a given trajectory, vulnerability is a measure of the consequence of violating a property. We propose a family of functions from which cost functions and other vulnerability indicators can be derived for any trajectory. There can be

  10. Intragroup Emotions: Physiological Linkage and Social Presence

    Science.gov (United States)

    Järvelä, Simo; Kätsyri, Jari; Ravaja, Niklas; Chanel, Guillaume; Henttonen, Pentti

    2016-01-01

    We investigated how technologically mediating two different components of emotion—communicative expression and physiological state—to group members affects physiological linkage and self-reported feelings in a small group during video viewing. In different conditions the availability of second screen text chat (communicative expression) and visualization of group level physiological heart rates and their dyadic linkage (physiology) was varied. Within this four person group two participants formed a physically co-located dyad and the other two were individually situated in two separate rooms. We found that text chat always increased heart rate synchrony but HR visualization only with non-co-located dyads. We also found that physiological linkage was strongly connected to self-reported social presence. The results encourage further exploration of the possibilities of sharing group member's physiological components of emotion by technological means to enhance mediated communication and strengthen social presence. PMID:26903913

  11. Intragroup emotions: physiological linkage and social presence

    Directory of Open Access Journals (Sweden)

    Simo eJärvelä

    2016-02-01

    Full Text Available We investigated how technologically mediating two different components of emotion – communicative expression and physiological state – to group members affects physiological linkage and self-reported feelings in a small group during video viewing. In different conditions the availability of second screen text chat (communicative expression and visualization of group level physiological heart rates and their dyadic linkage (physiology was varied. Within this four person group two participants formed a physically co-located dyad and the other two were individually situated in two separate rooms. We found that text chat always increased heart rate synchrony but HR visualization only with non-co-located dyads. We also found that physiological linkage was strongly connected to self-reported social presence. The results encourage further exploration of the possibilities of sharing group member’s physiological components of emotion by technological means to enhance mediated communication and strengthen social presence.

  12. On the natural diet of Daphnia laevis in the eutrophic Pampulha reservoir (Belo Horizonte, Minas Gerais

    Directory of Open Access Journals (Sweden)

    E. M. ESKINAZI-SANT'ANNA

    Full Text Available The aim of this study was to assess the major food items ingested by adult specimens of Daphnia laevis within the eutrophic Pampulha reservoir in Belo Horizonte, Minas Gerais, Brazil. The gut content was analyzed after addition of sodium hypochlorite and also through the examination of dissected guts under scanning electron microscopy. The results showed that Chlorophyceae was the main food item ingested, representing c. 80.5% of the total ingested food. Moreover, Eutetramorus fottii, Coelastrum pseudomicroporum and Oocystis lacustris, the dominant phytoplankton species within the reservoir, were the most frequent cells found in the gut contents. Euglenophyta also represented an important food item accounting for 15% of the ingested material, including mainly Trachelomonas volvocina and Euglena oxyuris, although less abundant in the reservoir (< 10% of total phytoplankton. Blue-green algae occurred at much lower percentages in the guts than in the phytoplankton. A small amount of undigested Microcystis aeruginosa colonies were also found in the gut content of D. laevis. Scanning electron microscopy results showed that, besides phytoplankton cells, a great amount of abiogenic material was also ingested. The amount of this inorganic material increased considerably in the tract (from 15% to 75% of the gut content, when a peak of D. laevis was observed in the reservoir. Our assumption is that the ingestion of this inorganic material can be a strategy used by D. laevis to obtain additional food supply.

  13. On the natural diet of Daphnia laevis in the eutrophic Pampulha reservoir (Belo Horizonte, Minas Gerais

    Directory of Open Access Journals (Sweden)

    ESKINAZI-SANT'ANNA E. M.

    2002-01-01

    Full Text Available The aim of this study was to assess the major food items ingested by adult specimens of Daphnia laevis within the eutrophic Pampulha reservoir in Belo Horizonte, Minas Gerais, Brazil. The gut content was analyzed after addition of sodium hypochlorite and also through the examination of dissected guts under scanning electron microscopy. The results showed that Chlorophyceae was the main food item ingested, representing c. 80.5% of the total ingested food. Moreover, Eutetramorus fottii, Coelastrum pseudomicroporum and Oocystis lacustris, the dominant phytoplankton species within the reservoir, were the most frequent cells found in the gut contents. Euglenophyta also represented an important food item accounting for 15% of the ingested material, including mainly Trachelomonas volvocina and Euglena oxyuris, although less abundant in the reservoir (< 10% of total phytoplankton. Blue-green algae occurred at much lower percentages in the guts than in the phytoplankton. A small amount of undigested Microcystis aeruginosa colonies were also found in the gut content of D. laevis. Scanning electron microscopy results showed that, besides phytoplankton cells, a great amount of abiogenic material was also ingested. The amount of this inorganic material increased considerably in the tract (from 15% to 75% of the gut content, when a peak of D. laevis was observed in the reservoir. Our assumption is that the ingestion of this inorganic material can be a strategy used by D. laevis to obtain additional food supply.

  14. Do lake littoral benthic invertebrates respond differently to eutrophication, hydromorphological alteration, land use and fish stocking?

    Directory of Open Access Journals (Sweden)

    Šiling Rebeka

    2016-01-01

    Full Text Available In order to provide adequate guidelines in freshwater management, managers need reliable bioindicators that can respond differently to varied stressors. Managers also have to consider hierarchical structure of environmental factors. Thus, our research aims to test the independence of taxa responses along environmental gradients and to examine in what order natural and anthropogenic factors constrain the structure of littoral benthic assemblages. The rank of explained variance of littoral benthic assemblage's variable group hierarchy was: land use > landscape characteristics > eutrophication > fish stocking > hydromorphological alteration. We determined nine gradients (two natural and seven stressor gradients, separated into five groups based on statistically significant differences in responsiveness of taxa. Apart from responsiveness to natural factors, littoral benthic invertebrates could be used as bioindicators for stressors reflecting urbanization, eutrophication, hydromorphological alteration and fish stocking. The taxonomical composition of littoral benthic invertebrates, especially when taxa with preference for certain relatively narrow environmental conditions along gradients are present, can be used to identify effects of key stressors. Our findings have profound implications for ecological assessment and management of lakes, as they indicate that benthic invertebrates can be used when the effects of multiple stressors need to be disentangled.

  15. Assessment of Ilam Reservoir Eutrophication Response in Controlling Water Inflow

    Directory of Open Access Journals (Sweden)

    Fereshteh Nourmohammadi Dehbalaei

    2016-12-01

    Full Text Available In this research, a 2D laterally averaged model of hydrodynamics and water quality, CE-QUAL-W2, was applied to simulate water quality parameters in the Ilam reservoir. The water quality of Ilam reservoir was obtained between mesotrophic and eutrophic based on the measured data including chlorophyll a, total phosphorus and subsurface oxygen saturation. The CE-QUAL-W2 model was calibrated and verified by using the data of the year 2009 and 2010, respectively. Nutrients, chlorophyll a and dissolved oxygen were the water quality constituents simulated by the CE-QUAL-W2 model. The comparison of the simulated water surface elevation with the measurement records indicated that the flow was fully balanced in the numerical model. There was a good agreement between the simulated and measured results of the hydrodynamics and water quality constituents in the calibration and verification periods. Some scenarios have been made base on decreasing in water quantity and nutrient inputs of reservoir inflows. The results have shown that the water quality improvements of the Ilam reservoir will not be achieved by reducing a portion of the reservoir inflow. The retention time of water in reservoir would be changed by decreasing of inflows and it made of the negative effects on the chlorophyll-a concentration by reduction of nutrient inputs and keeping constant of discharge inflow to reservoir, the concentration of total phosphorus would be significantly changed and also the concentration of chlorophyll-a was constant approximately. Thus, the effects of control in nutrient inputs are much more than control in discharge inflows in the Ilam reservoir.

  16. Eutrophication Process on Coastal Lagoons of North of Sinaloa, Mexico

    Science.gov (United States)

    Escobedo-Urias, D.; Martinez-Lopez, A.

    2007-05-01

    Coastal ecosystems in the Gulf of California support diverse and important fisheries and are reservoirs of great biological diversity. In northern Sinaloa, population growth and development, as well as increased use of these natural systems for recreation, has substantially increased the pressure placed upon marine resources. Discharge of untreated wastewaters generated by diverse human activities has been notably altered its health and integrity, principally along the lagoon's eastern shore In the late 60s, agriculture moved into a dominant role in coastal northern Sinaloa. The coastal plain encompasses more than 200,000 hectares under cultivation that now introduces large amounts of organic material, pesticides, heavy metals, and fertilizers into the lagoon systems of Topolobampo and San Ignacio-Navachiste-Macapule System at drainage discharge points and a minor grade in Colorado Lagoon. These lagoons are shallow and exhibit low water quality, lost of lagoon depth, presence of toxic substances (heavy metals) near the discharge points of wastewaters, and presence of harmful algal blooms. With the aim of evaluate the nutrients loadings (wastewaters, groundwaters) and their effects on the coastal lagoons of north of Sinaloa, the preliminary analysis of the physical, chemical and biologic variables data series are analyzed. From 1987-2007 eutrophication process is identified in Topolobampo Complex show increase tendency in annual average concentrations of DIN (Dissolved Inorganic Nitrogen= NO2+NO3) from 0.5 μ M in 1987 to 2.7 μ M in 2006. Trophic Index (TRIX) values, low nutrient ratios (N: P and N: Si) and the phytoplanktonic community structure support this result. Preliminary results of nutrients loadings show a mayor contribution of wastewaters into the coastal zone.

  17. Linkage of A-to-I RNA editing in metazoans and the impact on genome evolution.

    Science.gov (United States)

    Duan, Yuange; Dou, Shengqian; Zhang, Hong; Wu, Changcheng; Wu, Mingming; Lu, Jian

    2017-10-18

    The adenosine-to-inosine (A-to-I) RNA editomes have been systematically characterized in various metazoan species, and many editing sites were found in clusters. However, it remains unclear whether the clustered editing sites tend to be linked in the same RNA molecules or not. By adopting a method originally designed to detect linkage disequilibrium of DNA mutations, we examined the editomes of ten metazoan species and detected extensive linkage of editing in Drosophila and cephalopods. The prevalent linkages of editing in these two clades, many of which are conserved between closely related species and might be associated with the adaptive proteomic recoding, are maintained by natural selection at the cost of genome evolution. Nevertheless, in worms and humans, we only detected modest proportions of linked editing events, the majority of which were not conserved. Furthermore, the linkage of editing in coding regions of worms and humans might be overall deleterious, which drives the evolution of DNA sites to escape promiscuous editing. Altogether, our results suggest that the linkage landscape of A-to-I editing has evolved during metazoan evolution. This present study also suggests that linkage of editing should be considered in elucidating the functional consequences of RNA editing. © The Author(s) 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  18. Understanding Care Linkage and Engagement Across 15 Adolescent Clinics: Provider Perspectives and Implications for Newly HIV-Infected Youth.

    Science.gov (United States)

    Philbin, Morgan M; Tanner, Amanda E; DuVal, Anna; Ellen, Jonathan M; Kapogiannis, Bill; Fortenberry, J Dennis

    2017-04-01

    The National HIV/AIDS Strategy emphasizes rapid care linkage and engagement for HIV-infected individuals, though many adolescents are never tested, delay entering care, and frequently drop out. We conducted 183 staff interviews at 15 adolescent medicine clinics (baseline, n = 64; Year 1, n = 60; Year 2, = 59). We used a constant comparative thematic method to examine how providers approached and discussed care linkage/engagement. Qualitative analyses revealed differences in providers' conceptualizations of linkage and engagement. Providers saw linkage as mechanistic and health system driven. It was defined by number of clinic visits and involved relatively little youth agency. In contrast, providers defined engagement by youths' responsibility and participation in their own care. Linkage and engagement are related but distinct aspects of care that require different resources and levels of staff involvement. Integrating an understanding of these differences into future interventions will allow clinic staff to help youth improve long-term health outcomes.

  19. Kinematic Synthesis for Linkages with Velocity Targets

    Science.gov (United States)

    de-Juan, Ana; Sancibrian, Ramon; García, Pablo; Viadero, Fernando; Iglesias, Miguel; Fernández, Alfonso

    A gradient-based optimization method for designing linkages with velocity targets is described. Two theoretical application cases are established for four-bar linkage. In the first, a constant-velocity module is proposed for a point on the coupler. In the second, the goal is the velocity components. These cases are studied with and without coordination with the input link. The results obtained are compared with another gradient-based approach, and show that the method works efficiently for these types of target.

  20. Some methods for blindfolded record linkage

    Directory of Open Access Journals (Sweden)

    Christen Peter

    2004-06-01

    Full Text Available Abstract Background The linkage of records which refer to the same entity in separate data collections is a common requirement in public health and biomedical research. Traditionally, record linkage techniques have required that all the identifying data in which links are sought be revealed to at least one party, often a third party. This necessarily invades personal privacy and requires complete trust in the intentions of that party and their ability to maintain security and confidentiality. Dusserre, Quantin, Bouzelat and colleagues have demonstrated that it is possible to use secure one-way hash transformations to carry out follow-up epidemiological studies without any party having to reveal identifying information about any of the subjects – a technique which we refer to as "blindfolded record linkage". A limitation of their method is that only exact comparisons of values are possible, although phonetic encoding of names and other strings can be used to allow for some types of typographical variation and data errors. Methods A method is described which permits the calculation of a general similarity measure, the n-gram score, without having to reveal the data being compared, albeit at some cost in computation and data communication. This method can be combined with public key cryptography and automatic estimation of linkage model parameters to create an overall system for blindfolded record linkage. Results The system described offers good protection against misdeeds or security failures by any one party, but remains vulnerable to collusion between or simultaneous compromise of two or more parties involved in the linkage operation. In order to reduce the likelihood of this, the use of last-minute allocation of tasks to substitutable servers is proposed. Proof-of-concept computer programmes written in the Python programming language are provided to illustrate the similarity comparison protocol. Conclusion Although the protocols described in

  1. The Barley Chromosome 5 Linkage Map

    DEFF Research Database (Denmark)

    Jensen, J.; Jørgensen, Jørgen Helms

    1975-01-01

    The distances between nine loci on barley chromosome 5 have been studied in five two-point tests, three three-point tests, and one four-point test. Our previous chromosome 5 linkage map, which contained eleven loci mapped from literature data (Jensen and Jørgensen 1975), is extended with four loci......-position is fixed on the map by a locus (necl), which has a good marker gene located centrally in the linkage group. The positions of the other loci are their distances in centimorgans from the 0-position; loci in the direction of the short chromosome arm are assigned positive values and those...

  2. The Potential Impacts of Climate Change Factors on Freshwater Eutrophication: Implications for Research and Countermeasures of Water Management in China

    OpenAIRE

    Rui Xia; Yuan Zhang; Andrea Critto; Jieyun Wu; Juntao Fan; Zhirong Zheng; Yizhang Zhang

    2016-01-01

    Water eutrophication has become one of the most serious aquatic environmental problems around the world. More and more research has indicated climate change as a major natural factor that will lead to the acceleration of eutrophication in rivers and lakes. However, understanding the mechanism of climate change’s effect on water eutrophication is difficult due to the uncertainties caused by its complex, non-linear process. There is considerable uncertainty about the magnitude of future tempera...

  3. Assessment of Eutrophication Quality in Greek Coastal Ecosystem (Eastern Mediterranean Sea)

    Science.gov (United States)

    Pavlidou, Alexandra; Rousselaki, Eleni; Assimakopoulou, Georgia; Tsapakis, Manolis; Simboura, Nomiki

    2014-05-01

    The Mediterranean Sea has always been considered as one of the most oligotrophic areas in the world, especially in the Eastern part of the Sea. However, eutrophication problems occur in some coastal areas of the Mediterranean (e.g. eastern coasts of Spain, Gulf of Lions, northern Adriatic Sea, Apulian coasts, Saronikos Gulf, Thessaloniki Bay, northern coasts of Greece, etc.). This work is focused on the assessment of the Eutrophication Quality in different coastal areas of Greece affected by various anthropogenic and natural pressures and was performed under the Water Framework Directive. A network of 28 sampling stations was used during two relevant sampling periods, April - May 2012 and March - April 2013, in the framework of the National Monitoring Project of Greece. The Eutrophication assessment method integrates chemical and biological parameters of the water column. A synthetic Eutrophication Index (E.I.) was produced for the greek coastal areas by Primpas et al. quality classification scheme, combining the concentrations of nutrients (phosphate, nitrate, nitrite, ammonia) and chlorophyll-α biomass into a single formula. The E.I. assesses the eutrophication status using a five scale scheme according to the requirements of WFD: (High) less than 0.04; (Good) 0.04-0.38; (moderate) 0.38-0.85; (poor) 0.85-1.51; (bad) >1.51. Nutrient and chlorophyll-a concentrations revealed significant spatial variation among the various coastal areas of Greece influenced by different point and/or diffuse anthropogenic pressures (related to nutrient enrichment), reflecting the level of human-induced impairment where an increase in nutrient loads leads to increased water quality problems. The assessment of E.I showed that during 2012, 32% of the selected coastal areas were characterized as Good, 54% as Moderate and 14% of the selected greek coastal areas were characterized as Poor. During 2012, none of the study areas corresponded to High or Bad eutrophication status. During 2013

  4. Availability of Insurance Linkage Programs in U.S. Emergency Departments

    Directory of Open Access Journals (Sweden)

    Mia Kanak

    2014-07-01

    Full Text Available Introduction: As millions of uninsured citizens who use emergency department (ED services are now eligible for health insurance under the Affordable Care Act, the ED is ideally situated to facilitate linkage to insurance. Forty percent of U.S. EDs report having an insurance linkage program. This is the first national study to examine the characteristics of EDs that offer or do not offer these programs. Methods: This was a secondary analysis of data from the National Survey for Preventive Health Services in U.S. EDs conducted in 2008-09. We compared EDs with and without insurance programs across demographic and operational factors using univariate analysis. We then tested our hypotheses using multivariable logistic regression. We also further examined program capacity and priority among the sub-group of EDs with no insurance linkage program. Results: After adjustment, ED-insurance linkage programs were more likely to be located in the West (RR= 2.06, 95% CI = 1.33 – 2.72. The proportion of uninsured patients in an ED, teaching hospital status, and public ownership status were not associated with insurance linkage availability. EDs with linkage programs also offer more preventive services (RR = 1.87, 95% CI = 1.37–2.35 and have greater social worker availability (RR = 1.71, 95% CI = 1.12–2.33 than those who do not. Four of five EDs with a patient mix of ≥25% uninsured and no insurance linkage program reported that they could not offer a program with existing staff and funding. Conclusion: Availability of insurance linkage programs in the ED is not associated with the proportion of uninsured patients served by an ED. Policy or hospital-based interventions to increase insurance linkage should first target the 27% of EDs with high rates of uninsured patients that lack adequate program capacity. Further research on barriers to implementation and cost effectiveness may help to facilitate increased adoption of insurance linkage programs. [West J

  5. Closed-chain principal vector linkages

    NARCIS (Netherlands)

    van der Wijk, V.; Flores, Paulo; Viadero, Fernando

    2015-01-01

    For high-speed robotics dynamic balance is an important property for low base vibrations and short cycle times. To consider dynamic balance in the beginning of the design process of a manipulator, mechanism solutions can be synthesized from principal vector linkages, which are fundamental kinematic

  6. An estimating function approach to linkage heterogeneity

    Indian Academy of Sciences (India)

    1985). However, in the pedigrees with fragile X syndrome, there is linkage heterogeneity between the two loci. We randomly sampled eight pedigrees and their 70 off- spring from the pedigree data provided in Oberlé et al. (1986) and Brown et al. (1987), where five pedigrees (no. 1, 2, 5,. 9 and 13) came from Oberlé et al.

  7. Dialogic Linkage and Resonance in Autism

    Science.gov (United States)

    Hobson, R. Peter; Hobson, Jessica A.; Garcia-Perez, Rosa; Du Bois, John

    2012-01-01

    We evaluated how children with autism make linguistic adjustments when talking with someone else. We devised two novel measures to assess (a) overall conversational linkage and (b) utterance-by-utterance resonance within dialogue between an adult and matched participants with and without autism (n = 12 per group). Participants with autism were…

  8. Principles, realities and challenges regarding institutional linkages ...

    African Journals Online (AJOL)

    This paper makes a strong case for the necessity of community linkage structures where participatory development with the ultimate object of community empowerment, self-sufficiency and self-dependency is pursued. Important principles regarding the nature of such structures were identified by participatory methods and ...

  9. Haldane and the analysis of linkage

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Genetics; Volume 96; Issue 5. HALDANE AND THE ANALYSIS OF LINKAGE. J .H. Edwards. HALDANE AT 125 Volume 96 Issue 5 November 2017 pp 783-794. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/jgen/096/05/0783-0794. Abstract ...

  10. Building linkages and bargaining power between smallholder ...

    African Journals Online (AJOL)

    Mo

    This paper emphasizes the importance of facilitating the process of linkages between smallholder farmers and service providers as a foundation for accessibility of inputs for soil fertility management at local level. The paper explains how, through the process of local organizational development, farmers are able to mobilize ...

  11. Linkage disequilibrium and association mapping of drought ...

    African Journals Online (AJOL)

    Drought stress is a major abiotic stress that limits crop production. Molecular association mapping techniques through linkage disequilibrium (LD) can be effectively used to tag genomic regions involved in drought stress tolerance. With the association mapping approach, 90 genotypes of cotton Gossypium hirsutum, from ...

  12. Linkage disequilibrium and association mapping of drought ...

    African Journals Online (AJOL)

    sunny t

    2016-11-16

    Nov 16, 2016 ... Drought stress is a major abiotic stress that limits crop production. Molecular association mapping techniques through linkage disequilibrium (LD) can be effectively used to tag genomic regions involved in drought stress tolerance. With the association mapping approach, 90 genotypes of cotton. Gossypium ...

  13. Composite Bloom Filters for Secure Record Linkage.

    Science.gov (United States)

    Durham, Elizabeth Ashley; Kantarcioglu, Murat; Xue, Yuan; Toth, Csaba; Kuzu, Mehmet; Malin, Bradley

    2014-12-01

    The process of record linkage seeks to integrate instances that correspond to the same entity. Record linkage has traditionally been performed through the comparison of identifying field values (e.g., Surname), however, when databases are maintained by disparate organizations, the disclosure of such information can breach the privacy of the corresponding individuals. Various private record linkage (PRL) methods have been developed to obscure such identifiers, but they vary widely in their ability to balance competing goals of accuracy, efficiency and security. The tokenization and hashing of field values into Bloom filters (BF) enables greater linkage accuracy and efficiency than other PRL methods, but the encodings may be compromised through frequency-based cryptanalysis. Our objective is to adapt a BF encoding technique to mitigate such attacks with minimal sacrifices in accuracy and efficiency. To accomplish these goals, we introduce a statistically-informed method to generate BF encodings that integrate bits from multiple fields, the frequencies of which are provably associated with a minimum number of fields. Our method enables a user-specified tradeoff between security and accuracy. We compare our encoding method with other techniques using a public dataset of voter registration records and demonstrate that the increases in security come with only minor losses to accuracy.

  14. Comparative proteomics exploring the molecular mechanism of eutrophic water purification using water hyacinth (Eichhornia crassipes).

    Science.gov (United States)

    Li, Xiong; Xi, Houcheng; Sun, Xudong; Yang, Yunqiang; Yang, Shihai; Zhou, Yanli; Zhou, Xinmao; Yang, Yongping

    2015-06-01

    Eutrophication is a serious threat to ecosystem stability and use of water resources worldwide. Accordingly, physical, chemical, and biological technologies have been developed to treat eutrophic water. Phytoremediation has attracted a great deal of attention, and water hyacinth (Eichhornia crassipes) is regarded as one of the best plants for purification of eutrophic water. Previous studies have shown that water hyacinths remove nitrogen (N) and phosphorus (P) via diverse processes and that they can inhibit the growth of algae. However, the molecular mechanisms responsible for these processes, especially the role of proteins, are unknown. In this study, we applied a proteomics approach to investigate the protein dynamics of water hyacinth under three eutrophication levels. The results suggested that proteins with various functions, including response to stress, N and P metabolic pathways, synthesis and secretion, photosynthesis, biosynthesis, and energy metabolism, were involved in regulating water hyacinth to endure the excess-nutrient environment, remove N and P, and inhibit algal growth. The results help us understand the mechanism of purification of eutrophic water by water hyacinth and supply a theoretical basis for improving techniques for phytoremediation of polluted water.

  15. Comprehensive assessment of coastal eutrophication in Taiwan and its implications for management strategy.

    Science.gov (United States)

    Liu, Ta-Kang; Chen, Ping; Chen, Hou-Yu

    2015-08-15

    Due to the rapid population growth, anthropogenic activities result in agricultural, industrial, and urban diffuse runoffs that elevate the level of nutrients such as nitrogen and phosphorus in coastal waters. Currently there is no integrated analysis for coastal eutrophication in Taiwan. A comprehensive analysis of the coastal eutrophic status was performed in this study based on decade-long coastal water quality monitoring data from Taiwan's Environmental Protection Administration. A 3-tiered monitoring strategy is recommended based on the severity of the current eutrophication state. Results indicate that the most problematic area of coastal eutrophication is located in the estuary of the Donggang River (DGR) and its adjacent coastal waters, i.e., the Kao-Ping mouth (KPM) and Dapeng Bay (DPB) in south-western Taiwan. With a worsening eutrophic status, these areas demand intensive monitoring and research with higher spatial and temporal resolutions to evaluate the stresses of nutrient forcing and predict possible future responses. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Interactive effects of warming, eutrophication and size structure: impacts on biodiversity and food-web structure.

    Science.gov (United States)

    Binzer, Amrei; Guill, Christian; Rall, Björn C; Brose, Ulrich

    2016-01-01

    Warming and eutrophication are two of the most important global change stressors for natural ecosystems, but their interaction is poorly understood. We used a dynamic model of complex, size-structured food webs to assess interactive effects on diversity and network structure. We found antagonistic impacts: Warming increases diversity in eutrophic systems and decreases it in oligotrophic systems. These effects interact with the community size structure: Communities of similarly sized species such as parasitoid-host systems are stabilized by warming and destabilized by eutrophication, whereas the diversity of size-structured predator-prey networks decreases strongly with warming, but decreases only weakly with eutrophication. Nonrandom extinction risks for generalists and specialists lead to higher connectance in networks without size structure and lower connectance in size-structured communities. Overall, our results unravel interactive impacts of warming and eutrophication and suggest that size structure may serve as an important proxy for predicting the community sensitivity to these global change stressors. © 2015 John Wiley & Sons Ltd.

  17. Modeling of eutrophication and strategies for improvement of water quality in reservoirs.

    Science.gov (United States)

    Shourian, Mojtaba; Moridi, Ali; Kaveh, Mohammad

    2016-09-01

    The purpose of this study is to survey the thermal regime and eutrophication states in Ilam reservoir in Iran as the case study. For this purpose and to find solutions for improving the water's quality in the reservoir, two general strategies for reducing the entering pollution loads and water depletions from the reservoir's outlets were analyzed by use of the CE-QUAL-W2 model. Results of the simulation of the present situation show the existence of thermal stratification during summer, which results in the qualitative stratification in the reservoir. According to the qualitative criteria, the Ilam reservoir's state is between mesotrophic and eutrophic. Results of the scenarios of reduction of the nutrients show that in the scenario of 50% reduction of the phosphorus and nitrogen loads into the reservoir, the state of the reservoir would recover from eutrophic to semi-eutrophic. Also, release of water from the reservoir during September, October and November would cause the restoration of the quality of water in the reservoir. To avoid the occurrence of critical eutrophication in the reservoir, reducing the ponding time in the reservoir by fast depletion, preventing entrance of the upstream villages' sewage and agricultural drained waters, which are sources of nitrate and phosphate contamination into the rivers, and also management of the usage of agricultural fertilizers have been suggested.

  18. Climatic variability in combination with eutrophication drives adaptive responses in the gills of Lake Victoria cichlids.

    Science.gov (United States)

    van Rijssel, Jacco C; Hecky, Robert E; Kishe-Machumu, Mary A; Meijer, Saskia E; Pols, Johan; van Tienderen, Kaj M; Ververs, Jan D; Wanink, Jan H; Witte, Frans

    2016-12-01

    Textbook examples of adaptive radiation often show rapid morphological changes in response to environmental perturbations. East Africa's Lake Victoria, famous for its stunning adaptive radiation of cichlids, has suffered from human-induced eutrophication over the past decades. This cultural eutrophication is thought to be partly responsible for the dramatically reduced cichlid biodiversity, but climatic variability in itself might also have contributed to the eutrophication which resulted in low oxygen levels and decreased water transparency. To determine how recent environmental changes have influenced the lake and its cichlids over the past 50 years, we gathered environmental and meteorological variables and compared these with gill surface area of four cichlid species. We found that during the period of severe eutrophication and temperature increase (1980s), reduced wind speeds coincided with a reduction in oxygen levels and a decrease in both water temperature and transparency. The gill surface area in three out of the four cichlid species increased during this period which is consistent with adaptive change in response to increased hypoxia. During the 2000s, wind speeds, oxygen levels, water transparency and water temperature increased again, while cichlid gill surface area decreased. Our results imply that climatic changes and especially wind speed and direction might play a crucial role in tropical lake dynamics. The changes in Lake Victoria's water quality coincide with fluctuations in cichlid gill surface area, suggesting that these fish can respond rapidly to environmental perturbations, but also that climatic variability, together with continued eutrophication, might be detrimental to the lake's cichlid biodiversity.

  19. Discrete modeling of dynamics of zooplankton community at the different stages of an antropogeneous eutrophication.

    Science.gov (United States)

    Zholtkevych, G N; Bespalov, G Yu; Nosov, K V; Abhishek, Mahalakshmi

    2013-12-01

    Mathematical modeling is a convenient way for characterization of complex ecosystems. This approach was applied to study the dynamics of zooplankton in Lake Sevan (Armenia) at different stages of anthropogenic eutrophication with the use of a novel method called discrete modeling of dynamical systems with feedback (DMDS). Simulation demonstrated that the application of this method helps in characterization of inter- and intra-component relationships in a natural ecosystem. This method describes all possible pairwise inter-component relationships like "plus-plus," "minus-minus," "plus-minus," "plus-zero," "minus-zero," and "zero-zero" that occur in most ecosystems. Based on the results, a working hypothesis was formulated. It was found that the sensitivity to weak external influence in zooplanktons was the greatest during the mid period of eutrophication in Lake Sevan, whereas in the final stages of eutrophication, an outbreak in the biomass production of cyanobacteria was evident. To support this approach, a weak external disturbance in the form of magnetic storm was used to see its effect on species Daphnia longispina sevanica. A statistically significant correlation between the frequency of magnetic storms and the number of this species was revealed and an increase in the number of toxic cyanobacteria species as a consequence of eutrophication. This paper, for the first time, suggests a DMDS method, to diagnose impact of anthropogenic eutrophication on environment.

  20. What can ecosystem models tell us about the risk of eutrophication in the North Sea?

    Science.gov (United States)

    Saux Picart, S; Allen, J I; Butenschön, M; Artioli, Y; de Mora, L; Wakelin, S; Holt, J

    Eutrophication is a process resulting from an increase in anthropogenic nutrient inputs from rivers and other sources, the consequences of which can include enhanced algal biomass, changes in plankton community composition and oxygen depletion near the seabed. Within the context of the Marine Strategy Framework Directive, indicators (and associated threshold) have been identified to assess the eutrophication status of an ecosystem. Large databases of observations (in situ) are required to properly assess the eutrophication status. Marine hydrodynamic/ecosystem models provide continuous fields of a wide range of ecosystem characteristics. Using such models in this context could help to overcome the lack of in situ data, and provide a powerful tool for ecosystem-based management and policy makers. Here we demonstrate a methodology that uses a combination of model outputs and in situ data to assess the risk of eutrophication in the coastal domain of the North Sea. The risk of eutrophication is computed for the past and present time as well as for different future scenarios. This allows us to assess both the current risk and its sensitivity to anthropogenic pressure and climate change. Model sensitivity studies suggest that the coastal waters of the North Sea may be more sensitive to anthropogenic rivers loads than climate change in the near future (to 2040).

  1. How green is my river? A new paradigm of eutrophication in rivers.

    Science.gov (United States)

    Hilton, John; O'Hare, Matthew; Bowes, Michael J; Jones, J Iwan

    2006-07-15

    Although the process of eutrophication is reasonably well understood in lakes, there is currently no conceptual understanding of how eutrophication develops in rivers. This issue is addressed here. A review of the main processes controlling the development of eutrophication in lakes has been carried out as a precursor to considering the effect in rivers. The importance of hydraulic flushing in controlling algal growth suggests that short-retention-time rivers will show different effects compared to long retention-time, impounded rivers. The latter are likely to operate like lakes, moving from macrophyte domination to phytoplankton domination whereas the former move to benthic and filamentous algal domination. Subsequently, a conceptual model of the development of eutrophic conditions in short-retention-time rivers is developed. Although there is general agreement in the literature that an increase in nutrients, particularly phosphorus, is a pre-requisite for the eutrophic conditions to develop, there is little evidence in short-retention-time rivers that the plant (macro and micro) biomass is limited by nutrients and a good case can be made that the interaction of hydraulic drag with light limitation is the main controlling factor. The light limitation is brought about by the development of epiphytic algal films on the macrophyte leaves. The implications of this conceptual model are discussed and a series of observable effects are predicted, which should result if the model is correct.

  2. Eutrophication increases methane emission to the atmosphere in tropical lagoons: insights from two Ivory Coast sites

    Science.gov (United States)

    José-mathieu Koné, Yéfanlan; Vieira Borges, Alberto

    2017-04-01

    Eutrophication increases methane emission to the atmosphere in tropical lagoons: insights from two Ivory Coast sites. Y J M Koné (1) & A.V. Borges (2) (1) Centre de recherches océanologiques (CRO) d'Abidjan, (Ivory Coast) (2) University of Liège, Chemical Oceanography Unit, Liège, Belgium (Belgium) Eutrophication is a worldwide environmental problem and a definitive solution is far from being achieved, despite the large number of studies documenting its causes. In small aquatic ecosystems, excessive growth of macrophytes is a well known undesirable consequence of eutrophication. When these plants die and sink to the bottom the decomposing biomass depletes oxygen content in the water column thus leading to anoxia promoting methane (CH4) production. Here, we reported the CH4 data obtained during six campaigns covering the annual cycle in two small lagoons of Ivory Coast (Ono, Kodjoboué) that are contrasted in the degree of eutrophication and the corresponding coverage of macrophytes (e.g. Echinochloa pyramidalis, Eichhornia crassipes, Hydrilla verticillata). Our data showed a high spatio-temporal variability of CH4 within the lagoons and between the two systems, with CH4 concentrations in surface waters ranging between 80 to 74,604 nmol L-1. The highest CH4 concentration values were observed in the eutrophic Ono lagoon that is covered by 80% of macrophytes, suggesting that lagoons dominated by macrophytes are significant sources of CH4 toward the atmosphere.

  3. Transcriptome profiling of Galaxea fascicularis and its endosymbiont Symbiodinium reveals chronic eutrophication tolerance pathways and metabolic mutualism between partners

    Science.gov (United States)

    Lin, Zhenyue; Chen, Mingliang; Dong, Xu; Zheng, Xinqing; Huang, Haining; Xu, Xun; Chen, Jianming

    2017-01-01

    In the South China Sea, coastal eutrophication in the Beibu Gulf has seriously threatened reef habitats by subjecting corals to chronic physiological stress. To determine how coral holobionts may tolerate such conditions, we examined the transcriptomes of healthy colonies of the galaxy coral Galaxea fascicularis and its endosymbiont Symbiodinium from two reef sites experiencing pristine or eutrophied nutrient regimes. We identified 236 and 205 genes that were differentially expressed in eutrophied hosts and symbionts, respectively. Both gene sets included pathways related to stress responses and metabolic interactions. An analysis of genes originating from each partner revealed striking metabolic integration with respect to vitamins, cofactors, amino acids, fatty acids, and secondary metabolite biosynthesis. The expression levels of these genes supported the existence of a continuum of mutualism in this coral-algal symbiosis. Additionally, large sets of transcription factors, cell signal transduction molecules, biomineralization components, and galaxin-related proteins were expanded in G. fascicularis relative to other coral species. PMID:28181581

  4. Transcriptome profiling of Galaxea fascicularis and its endosymbiont Symbiodinium reveals chronic eutrophication tolerance pathways and metabolic mutualism between partners

    Science.gov (United States)

    Lin, Zhenyue; Chen, Mingliang; Dong, Xu; Zheng, Xinqing; Huang, Haining; Xu, Xun; Chen, Jianming

    2017-02-01

    In the South China Sea, coastal eutrophication in the Beibu Gulf has seriously threatened reef habitats by subjecting corals to chronic physiological stress. To determine how coral holobionts may tolerate such conditions, we examined the transcriptomes of healthy colonies of the galaxy coral Galaxea fascicularis and its endosymbiont Symbiodinium from two reef sites experiencing pristine or eutrophied nutrient regimes. We identified 236 and 205 genes that were differentially expressed in eutrophied hosts and symbionts, respectively. Both gene sets included pathways related to stress responses and metabolic interactions. An analysis of genes originating from each partner revealed striking metabolic integration with respect to vitamins, cofactors, amino acids, fatty acids, and secondary metabolite biosynthesis. The expression levels of these genes supported the existence of a continuum of mutualism in this coral-algal symbiosis. Additionally, large sets of transcription factors, cell signal transduction molecules, biomineralization components, and galaxin-related proteins were expanded in G. fascicularis relative to other coral species.

  5. Eutrophication dynamics in lake Baikal from remote sensing data

    Science.gov (United States)

    Pitarch, Jaime; Silow, Eugene; Krashchuk, Lyudmila S.; Pislegina, Elena V.; Shimaraeva, Svetlana V.; Izmestyeva, Lyubov R.; Santoleri, Rosalia; Moore, Marianne V.

    2017-04-01

    Lake Baikal, one of the oldest lakes on earth, the deepest (1642 m), and the largest in volume (23,615 cubic km) of all of Earth's freshwater bodies, is located nearly in the very center of Asia, 456 m above sea level. Baikal stretches for 636 km from the southwest to the northeast between 51°28' and 55°47' N, and 103°43' and 109°58' E. The area of Baikal's watershed is over 550,000 square km. Baikal is also unique in that its waters are rich in oxygen all the way to the bottom of the lake. A large number of the species living in Lake Baikal are endemic. In 1996, Lake Baikal was named a UNESCO Heritage Site, with Russia pledging to protect it. A number of recent studies have reported degradation of the benthic littoral zone such as proliferation of benthic algae, death of snails and endemic sponges, large coastal wash-ups of dead benthic algae and macrophytes, blooms of toxin-producing benthic cyanobacteria, and inputs of industrial contaminants. In the open, pelagic basins, changes in the eutrophication and water transparency have also been noticed. Such studies were based on in-situ collected data, at different spatial and temporal frequencies. Remote sensing (RS) offers a comprehensive monitoring of all littoral and open areas of the lake at a high and regular time frequency. The amount of ecological information retrieved by RS is much lower than that provided by in-situ data, but RS can determine the representativeness of the chosen in-situ stations and detect un-sampled zones that need monitoring. Additionally, RS provides a harmonized methodology in space and time, which is crucial if statistical information is going to be derived. On its turn, in-situ data is required as a ground truth to transform the RS signal into relevant ecological indicators. In this work, we provide the first results of a new international project aimed to re-analize archived RS data to study ecological changes in Lake Baikal and incorporate near-real time RS data to monitoring

  6. Permeable Reactive Barriers Designed To Mitigate Eutrophication Alter Bacterial Community Composition and Aquifer Redox Conditions

    Science.gov (United States)

    Hiller, Kenly A.; Foreman, Kenneth H.; Weisman, David

    2015-01-01

    Permeable reactive barriers (PRBs) consist of a labile carbon source that is positioned to intercept nitrate-laden groundwater to prevent eutrophication. Decomposition of carbon in the PRB drives groundwater anoxic, fostering microbial denitrification. Such PRBs are an ideal habitat to examine microbial community structure under high-nitrate, carbon-replete conditions in coastal aquifers. We examined a PRB installed at the Waquoit Bay National Estuarine Research Reserve in Falmouth, MA. Groundwater within and below the PRB was depleted in oxygen compared to groundwater at sites upgradient and at adjacent reference sites. Nitrate concentrations declined from a high of 25 μM upgradient and adjacent to the barrier to <0.1 μM within the PRB. We analyzed the total and active bacterial communities filtered from groundwater flowing through the PRB using amplicons of 16S rRNA and of the 16S rRNA genes. Analysis of the 16S rRNA genes collected from the PRB showed that the total bacterial community had high relative abundances of bacteria thought to have alternative metabolisms, such as fermentation, including candidate phyla OD1, OP3, TM7, and GN02. In contrast, the active bacteria had lower abundances of many of these bacteria, suggesting that the bacterial taxa that differentiate the PRB groundwater community were not actively growing. Among the environmental variables analyzed, dissolved oxygen concentration explained the largest proportion of total community structure. There was, however, no significant correlation between measured environmental parameters and the active microbial community, suggesting that controls on the active portion may differ from the community as a whole. PMID:26231655

  7. Accuracy of death certification and hospital record linkage for identification of incident stroke

    Directory of Open Access Journals (Sweden)

    Luben Robert N

    2008-11-01

    Full Text Available Abstract Background There is little information on the validity of using record linkage with routinely collected data for case ascertainment of stroke in large population-based studies in the UK. We examined the accuracy of these routine record linkage approaches for identifying incident stroke cases in a large UK population-based study, the European Prospective Investigation into Cancer (EPIC-Norfolk cohort. Methods We examined a sample of hospital records of incident stroke cases identified by linkage with two routine data sources, death certificates and a national hospital record linkage system (ENCORE, using predefined study criteria. Two senior Specialist Registrars with clinical experience in stroke medicine examined the hospital records and searched for the evidence of stroke recorded in these records between 1993/97–2003. Results Of 520 incident strokes identified between 1993/1997–2003 using record linkage systems in the EPIC-Norfolk, a sample of 250 medical case notes were examined between March and July 2004. Using the predefined study criteria, there were 191 definite strokes (76%, 20 probable strokes (8%, 11 possible strokes and 11 cases of transient ischaemic attacks (4% each i.e. 233/250 (93% with possible or definite stroke or transient ischaemic attacks. Stroke could not be verified using hospital records in 13 cases (5% and 4 cases (2% had other diagnoses: 3 cases of vascular dementia and 1 case of benign intracranial hypertension. The diagnosis of stroke in 185 out of 250 cases identified in the EPIC-Norfolk (74.0% was supported by radiological evidence using WHO criteria. Conclusion Death certificates and hospital record linkage in this British prospective study have a high accuracy or positive predictive value in correctly identifying incident stroke cases.

  8. Editorial - A critical perspective on geo-engineering for eutrophication management in lakes

    DEFF Research Database (Denmark)

    Lürling, Miquel; Mackay, Eleanor; Reitzel, Kasper

    2016-01-01

    will not be applicable in the field because of costs and other constraints. Aluminium and lanthanum modified compounds are among the most effective compounds for targeting P. Flocculants and ballast compounds can be used to sink cyanobacteria, in the short term. We emphasize that the first step in managing...... kit, may ensure successful management of eutrophication through a range of target effects. In addition, novel developments in modified zeolites offer simultaneous P and nitrogen control. To facilitate research and reduce the delay from concept to market a multi-national centre of excellence...... eutrophication is a system analysis that will reveal the main water and P flows and the biological structure of the waterbody. These site specific traits can be significant confounding factors dictating successful eutrophication management. Geo-engineering techniques, considered collectively, as part of a tool...

  9. Spatial differentiation of marine eutrophication damage indicators based on species density

    DEFF Research Database (Denmark)

    Cosme, Nuno Miguel Dias; Jones, Miranda C.; Cheung, William W. L.

    2016-01-01

    Marine eutrophication refers to an ecosystem response to the loading of nutrients, typically nitrogen (N), to coastal waters where several impacts may occur. The increase of planktonic growth due to N-enrichment fuels the organic carbon cycles and may lead to excessive oxygen depletion in benthic...... an indicator of the Ecosystem Response (ER) to N-uptake. The loss of species richness expressed by the ER is further modelled to a marine eutrophication Ecosystem Damage (meED) indicator, as an absolute metric of time integrated number of species disappeared (speciesyr), by applying a newly...... to the environmental relevance of meED scores and to the harmonisation of marine eutrophication impacts with other ecosystem-damage Life Cycle Impact Assessment (LCIA) indicators. The novel features improve current methodologies and support the adoption of the meED indicator in LCIA for the characterization...

  10. Metal accumulation by submerged macrophytes in eutrophic lakes at the watershed scale.

    Science.gov (United States)

    Xing, Wei; Wu, Haoping; Hao, Beibei; Liu, Guihua

    2013-10-01

    Metal concentrations (Al, Ba, Ca, K, Li, Mg, Na, Se, Sr and Ti) in submerged macrophytes and corresponding water and sediments were studied in 24 eutrophic lakes along the middle and lower reaches of the Yangtze River (China). Results showed that these eutrophic lakes have high metal concentrations in both water and sediments because of human activities. Average concentrations of Al and Na in tissues of submerged macrophytes were very high in sampled eutrophic lakes. By comparison, Ceratophyllum demersum and Najas marina accumulated more metals (e.g. Ba, Ca, K, Mg, Na, Sr and Ti). Strong positive correlations were found between metal concentrations in tissues of submerged macrophytes, probably because of co-accumulation of metals. The concentrations of Li, Mg, Na and Sr in tissues of submerged macrophytes significantly correlated with their corresponding water values, but not sediment values.

  11. Bioaccumulation of heavy metals by submerged macrophytes: looking for hyperaccumulators in eutrophic lakes.

    Science.gov (United States)

    Xing, Wei; Wu, Haoping; Hao, Beibei; Huang, Wenmin; Liu, Guihua

    2013-05-07

    To directly select submerged macrophytes with high accumulation capability from the field, 24 eutrophic lakes along the middle and lower reaches of the Yangtze River were investigated in the study. These eutrophic lakes have large amounts of heavy metals in both water and sediments because of human activities. The results showed that Najas marina is a hyperaccumulator of As and Cd, Ceratophyllum demersum is a hyperaccumulator of Co, Cr, and Fe, and Vallisneria natans is a hyperaccumulator of Pb. Strong positive correlations were found between concentrations of heavy metals in tissues of submerged macrophytes, probably because of coaccumulation of heavy metals. However, for most heavy metals, no significant correlations were found between submerged macrophytes and their surrounding environments. In conclusion, N. marina, C. demersum, and V. natans are good candidate species for removing heavy metals from eutrophic lakes.

  12. A fabrication process for electrostatic microactuators with integrated gear linkages

    NARCIS (Netherlands)

    Legtenberg, R.; Legtenberg, Rob; Berenschot, Johan W.; Elwenspoek, Michael Curt; Fluitman, J.H.J.

    A surface micromachining process is presented which has been used to fabricate electrostatic microactuators. These microactuators are interconnected with each other and linked to other movable microstructures by integrated gear linkages. The gear linkages consist of rotational and linear gear

  13. Autosomal dominant familial spastic paraplegia; Linkage analysis and evidence for linkage to chromosome 2p

    Energy Technology Data Exchange (ETDEWEB)

    Figlewicz, D.A. [Univ. of Rochester, NY (United States); Dube, M.P.; Rouleau, G.A. [McGill Univ., Montreal (Canada)] [and others

    1994-09-01

    Familial spastic paraplegia (FSP) is a degenerative disorder of the motor system characterized by progressive weakness and spasticity of the lower limbs. Little is known about the pathophysiology of this disorder. FSP can be inherited as an autosomal dominant (AD), autosomal recessive, or X-linked trait. We have undertaken linkage analysis for a group of 36 AD FSP families from which we have collected blood samples from 427 individuals, including 148 affected individuals. Typing of polymorphic markers has allowed us to exclude more than 50% of the genome. Recently, linkage for AD FSP to a locus on chromosome 14q was reported. Our AD FSP kindreds were tested for linkage to markers spanning the 20 cM region between D14S69 and D14S66; however, we were not able to establish linkage for any of our families to chromosome 14. Lod scores suggestive of linkage for some AD FSP kindreds have been obtained for markers on chromosome 2p. We have tested seven polymorphic markers spanning the region between D2S405 and D2S177. Our highest aggregate lod score, including all families tested, was obtained at the locus D2S352: 2.4 at 20 cM. Results from HOMOG analysis for linkage heterogeneity will be reported.

  14. Mother/child bond in mothers of overweight and eutrophic children: depression and socioeconomic factors

    Directory of Open Access Journals (Sweden)

    Patricia Vieira Spada

    2011-03-01

    Full Text Available Objective: To verify the presence of depression, age, level of schooling, occupation, marital status, number of children and nutritional status (maternal and of the child in mothers of overweight and eutrophic children and relate the data to mother/child bonding. Methods: A total of 120 mothers of children aged up to 10 years participated; 30 of them were overweight and 30 were eutrophic (low-income bracket; 30 were overweight and 30 eutrophic (high-income bracket. The control group was composed of eutrophic children paired according to sex, age, level of schooling, and social condition. Data collection was made through interviews. The assessment instruments were: Mother/Child Bonding Assessment Protocol and Beck Depression Inventory. The nutritional classification was defined by calculation of the body mass index, as per the curves of the World Health Organization. For statistics, McNemar, χ2, and Fisher’s exact tests were used. A 5% level of rejection of the null hypothesis was set. Results: There was no significant result between mother/child bonding and the variables studied, or between the presence of depression and level of schooling, marital status, occupation, and maternal nutritional status. Nevertheless, mothers of eutrophic children (high-income bracket showed less depression than mothers of eutrophic children (low-income bracket. Mothers with three or more children displayed more depression than mothers with less than three children. Mothers under 30 years of age showed more depression than mothers aged 30 years or older. Conclusion: There was no significant result between mother/child bonding and the variables studied, but the bond was compromised in all mothers of the sample. There was a significant result regarding the presence of depression.

  15. Editorial - A critical perspective on geo-engineering for eutrophication management in lakes.

    Science.gov (United States)

    Lürling, Miquel; Mackay, Eleanor; Reitzel, Kasper; Spears, Bryan M

    2016-06-15

    Eutrophication is the primary worldwide water quality issue. Reducing excessive external nutrient loading is the most straightforward action in mitigating eutrophication, but lakes, ponds and reservoirs often show little, if any, signs of recovery in the years following external load reduction. This is due to internal cycling of phosphorus (P). Geo-engineering, which we can here define as activities intervening with biogeochemical cycles to control eutrophication in inland waters, represents a promising approach, under appropriate conditions, to reduce P release from bed sediments and cyanobacteria accumulation in surface waters, thereby speeding up recovery. In this overview, we draw on evidence from this special issue Geoengineering in Lakes, and on supporting literature to provide a critical perspective on the approach. We demonstrate that many of the strong P sorbents in the literature will not be applicable in the field because of costs and other constraints. Aluminium and lanthanum modified compounds are among the most effective compounds for targeting P. Flocculants and ballast compounds can be used to sink cyanobacteria, in the short term. We emphasize that the first step in managing eutrophication is a system analysis that will reveal the main water and P flows and the biological structure of the waterbody. These site specific traits can be significant confounding factors dictating successful eutrophication management. Geo-engineering techniques, considered collectively, as part of a tool kit, may ensure successful management of eutrophication through a range of target effects. In addition, novel developments in modified zeolites offer simultaneous P and nitrogen control. To facilitate research and reduce the delay from concept to market a multi-national centre of excellence is required. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Environmental Impact Analysis of Acidification and Eutrophication Due to Emissions from the Production of Concrete

    Directory of Open Access Journals (Sweden)

    Tae Hyoung Kim

    2016-06-01

    Full Text Available Concrete is a major material used in the construction industry that emits a large amount of substances with environmental impacts during its life cycle. Accordingly, technologies for the reduction in and assessment of the environmental impact of concrete from the perspective of a life cycle assessment (LCA must be developed. At present, the studies on LCA in relation to greenhouse gas emission from concrete are being carried out globally as a countermeasure against climate change. However, the studies on the impact of the substances emitted in the concrete production process on acidification and eutrophication are insufficient. As such, assessing only a single category of environmental impact may cause a misunderstanding about the environmental friendliness of concrete. The substances emitted in the concrete production process have an impact not only on global warming but also on acidification and eutrophication. Acidification and eutrophication are the main causes of air pollution, forest destruction, red tide phenomena, and deterioration of reinforced concrete structures. For this reason, the main substances among those emitted in the concrete production process that have an impact on acidification and eutrophication were deduced. In addition, an LCA technique through which to determine the major emissions from concrete was proposed and a case analysis was carried out. The substances among those emitted in the concrete production process that are related to eutrophication were deduced to be NOx, NH3, NH4+, COD, NO3−, and PO43−. The substances among those emitted in the concrete production process that are related to acidification, were found to be NOx, SO2, H2S, and H2SO4. The materials and energy sources among those input into the concrete production process, which have the biggest impact on acidification and eutrophication, were found to be coarse aggregate and fine aggregate.

  17. Response of Benthic Macrofauna to Eutrophication in a Mesocosm Experiment: Ecosystem Resilience Prevents Hypoxic Conditions

    Directory of Open Access Journals (Sweden)

    Panagiotis D. Dimitriou

    2017-12-01

    Full Text Available A benthic-pelagic mesocosm experiment was performed to study how the benthic macrofaunal community responds to a eutrophication gradient. The novel experimental setup allowed the induction of an eutrophication gradient in the water column and the detailed documentation of the response of the benthos in terms of biodiversity and ecosystem processes. Nine mesocosms were deployed in the facilities of the Hellenic Center for Marine Research in Crete in the eastern Mediterranean. The mesocosms were 4 m deep, contained 1.5 m3 coastal water, and included 85 liters of undisturbed sediment at the bottom. No water or sediment exchange was allowed. The experimental design included a Control and two eutrophication levels (Low and High for the 58-day duration of the experiment. Macrofaunal samples were collected at the end of the experiment from each mesocosm and compared to the ones collected at the beginning of the experiment from the sediment collection area. Results show that the High eutrophication treatment differed significantly from the Control and Low treatments in terms of macrofaunal species composition, diversity, ecological status and ecosystem processes. The increased availability of organic matter in the sediment caused differences in macrofaunal community structure by favoring deposit-feeding species with high bioturbation ability, which significantly increased their abundance. The increased bioturbation potential of the new community combined with the high organic matter consumption contributed to the oxygenation of the sediment within the mesocosm, preventing the creation of hypoxic conditions in the sediment and maintaining ecosystem health despite the highly eutrophic conditions and significant changes in sediment geochemical variables. In the oligotrophic eastern Mediterranean, healthy benthic ecosystems may use existing ecosystem processes to “buffer” the negative effects caused by eutrophication.

  18. Immature mosquitoes (Diptera: Culicidae in a eutrophic landfill tank from State of Rio de Janeiro, Brazil

    Directory of Open Access Journals (Sweden)

    Jeronimo Alencar

    2013-12-01

    Full Text Available Introduction To determine the faunal composition of immature culicids inhabiting a percolation tank in the landfill of Sapucaia, State of Rio de Janeiro, Brazil, immature mosquitoes were collected over a two-day period during the third weeks of April, August and October 2011. Results The species found were Culex usquatus, Lutzia bigoti, Anopheles argyritarsis and Limatus durhamii. This study is the first to report the colonization of eutrophic breeding sites by these species. Conclusions The oviposition behavior observed in this study suggests a secondary adaptation or change in habit to select eutrophic environments during the developmental stages of the observed species.

  19. Lake Peipsi's eutrophication issue: new insights into large scale water quality modeling

    Science.gov (United States)

    Fink, Gabriel; Flörke, Martina

    2017-04-01

    The large and shallow European Lake Peipsi was polluted with phosphorus loadings from different point and diffuse sources over decades. The lake's trophic state changed from mesotrophic to eutrophic and hypertrophic. In the 1990s phosphorus pollution dropped significantly. However, more than twenty years later the lake is still eutrophic (L. Peipsi s.s.) and hypertrophic (L. Pihkva). It has been determined that internal loadings from a large nutrient pool in the lake's sediments play an important role in the actual phosphorus balance. For a pursuing and comprehensive understanding, there is a need for detailed and integrated water quality data. This is necessary to assess the current state as well as the younger lake nutrient history. However, in-situ data are scarce and difficult to access. To overcome this data sparse situation the global integrated modeling framework WaterGAP3 was applied (i) to test the applicability of a global scale (5 arc minutes resolution) water quality model in a local scale eutrophication study, and (ii) to provide a detailed local analysis of the eutrophication issue for Lake Peipsi. In this setting WaterGAP3 provides a detailed description of phosphorus sources, loadings and concentrations. Furthermore the newly implemented two box eutrophication module provides a long term description of total phosphorus (TP) concentrations in lakes, the consequent potential for toxic algae blooms, and the TP balance components such as the sediment storage. The WaterGAP3 global results such as river discharge, TP loads from different sectors, TP concentration in the lake and in the catchments river system cover a period of 1990-2010. Our model results indicate that the agricultural sector (diffuse source) is the primary source of TP pollution in the Lake Peipsi catchment (45%) followed by background sources (diffuse sources) such as atmospheric deposition and weathering (33%), and domestic point sources (19%). The model results confirm the reported

  20. The first linkage map of the American mink (Mustela vison)

    DEFF Research Database (Denmark)

    Anistoroaei, Razvan Marian; Menzorov, A.; Serov, O.

    2007-01-01

    Described herein, the first microsatellite linkage map for the American mink consists of 85 microsatellite markers resolved into 17 linkage groups. The map was constructed using 92 F1 progeny from five sire families created by crossing mink with different colour types. The linkage groups ranged f...

  1. Prospects for Environmental Communication Based on 25 Years of Newspaper Coverage of Climate Change and Eutrophication in Finland

    Science.gov (United States)

    Lyytimäki, Jari

    2015-01-01

    Research on long-term media coverage of environmental issues has focused predominantly on English-speaking industrialized countries and on single isolated topics. This article presents a comparative analysis of the Finnish newspaper coverage of climate change and eutrophication from 1990-2014. The coverage of eutrophication showed an annual cycle…

  2. The Influence of a Eutrophic Lake to the River Downstream : Spatiotemporal Algal Composition Changes and the Driving Factors

    NARCIS (Netherlands)

    Yu, Q.; Chen, Y.; Liu, Z.; Van de Giesen, N.C.; Zhu, D.

    2015-01-01

    Algal blooms have been frequently found at the upper reaches of the Tanglang River, which is downstream from the eutrophic Dianchi Lake. The eutrophic lake upstream is considered to be a potential source of phytoplankton, which contributes to the development of harmful algal blooms in the river

  3. Management of eutrophication in Lake De Kuil (The Netherlands) using combined flocculant – Lanthanum modified bentonite treatment

    NARCIS (Netherlands)

    Waajen, Guido; van Oosterhout, Frank; Douglas, Grant; Lürling, Miquel

    2016-01-01

    Abstract Eutrophication of Lake De Kuil (The Netherlands, 6.7 ha, maximum depth 9 m) has frequently caused cyanobacterial blooms resulting in swimming bans or the issue of water quality warnings during summer. The eutrophication was mainly driven by sediment phosphorus (P)-release. The external

  4. Regional development through rural-urban linkages

    OpenAIRE

    Mushi, Nimrod Shitrael

    2004-01-01

    Many households have spanning livelihoods that draw on rural and urban resource opportunities. Urban and rural areas are closely linked, each contributing to the other, they therefore need to be considered jointly in development planning. The absence of rural development policies that recognise and seek to take advantage of positive aspects of rural-urban linkages in the impact regions of many cities in Developing Countries is a constraint to both rural and urban development. This policy vacu...

  5. LINKAGES FOR QUADRUPED BIO-ROBOT WALKING

    OpenAIRE

    Ovidiu ANTONESCU; Cătălina ROBU; Paun ANTONESCU,

    2015-01-01

    This paper analyses the Jansen mechanism. It then presents a few pictures of a mobile quadruped robot, which will help to describe how the robot moves. We take into consideration the kinematic scheme of the spatial mechanism with bars (spatial linkage), which is used for each of the four robot legs. Each leg mechanism is driven by two rotate brushless actuators that include a spur gear low-ratio transmission. By means of analyzing the kinematic scheme, the spatial mechanism mob...

  6. Have North-South Growth Linkages Changed?

    OpenAIRE

    Willy W. Hoffmaister; Mahmood Pradhan; Hossein Samiei

    1996-01-01

    This paper provides preliminary econometric evidence suggesting that the traditional trade-based business cycle linkages between the North and the South have changed. Many countries in the South, in particular in Asia, appear to have become more resilient to cyclical movements in the North, and to have come to play a more significant role in sustaining global activity, in particular during the 1991-93 slowdown. A number of factors may have contributed to these changes: improved domestic polic...

  7. Commodities and Linkages: Meeting the Policy Challenge

    OpenAIRE

    Kaplinsky, Raphael; Morris, Adam; Kaplan, David

    2011-01-01

    The results of detailed empirical enquiry into the nature and determinants of the breadth and depth of linkages in and out of the commodities sector in eight SSA countries (Angola, Botswana, Gabon, Ghana, Nigeria, South Africa Tanzania, and Zambia) and six sectors (copper, diamonds, gold, oil and gas, mining services and timber) has shown extensive scope for industrial development (MMCP DP 13, 2011). A primary conclusion of this research was that policy in both the private and public realm wa...

  8. Research – Extension – Fish Farmer Linkage System in Coastal and ...

    African Journals Online (AJOL)

    Instead, Scientists involved in basic, applied and adaptive research together with extension agents and farmers should be seen as participants in a single Agricultural knowledge and information system. The study examined the research – extension –fish farmer linkage system in coastal and inland states of Nigeria.

  9. Linkage of atopic dermatitis to chromosomes 4q22, 3p24 and 3q21

    DEFF Research Database (Denmark)

    Christensen, Ulla; Møller-Larsen, Steffen; Nyegaard, Mette

    2009-01-01

    Atopic dermatitis (AD) is a common, itchy skin disease of complex inheritance characterized by dermal and epidermal inflammation. The heritability is considerable and well documented. To date, four genome scans have examined the AD phenotype, showing replicated linkage at 3p26-22, 3q13-21 and 18q11...

  10. Upland Forest Linkages to Seasonal Wetlands: Litter Flux, Processing, and Food Quality

    Science.gov (United States)

    Brian J. Palik; Darold P. Batzer; Christel Kern

    2005-01-01

    The flux of materials across ecosystem boundaries has significant effects on recipient systems. Because of edge effects, seasonal wetlands in upland forest are good systems to explore these linkages. The purpose of this study was to examine flux of coarse particulate organic matter as litter fall into seasonal wetlands in Minnesota, and the relationship of this flux to...

  11. Methods for genetic linkage analysis using trisomies

    Energy Technology Data Exchange (ETDEWEB)

    Feingold, E. [Emory Univ. School of Public Health, Atlanta, GA (United States); Lamb, N.E.; Sherman, S.L. [Emory Univ., Atlanta, GA (United States)

    1995-02-01

    Certain genetic disorders are rare in the general population, but more common in individuals with specific trisomies. Examples of this include leukemia and duodenal atresia in trisomy 21. This paper presents a linkage analysis method for using trisomic individuals to map genes for such traits. It is based on a very general gene-specific dosage model that posits that the trait is caused by specific effects of different alleles at one or a few loci and that duplicate copies of {open_quotes}susceptibility{close_quotes} alleles inherited from the nondisjoining parent give increased likelihood of having the trait. Our mapping method is similar to identity-by-descent-based mapping methods using affected relative pairs and also to methods for mapping recessive traits using inbred individuals by looking for markers with greater than expected homozygosity by descent. In the trisomy case, one would take trisomic individuals and look for markers with greater than expected homozygosity in the chromosomes inherited from the nondisjoining parent. We present statistical methods for performing such a linkage analysis, including a test for linkage to a marker, a method for estimating the distance from the marker to the trait gene, a confidence interval for that distance, and methods for computing power and sample sizes. We also resolve some practical issues involved in implementing the methods, including how to use partially informative markers and how to test candidate genes. 20 refs., 5 figs., 1 tab.

  12. Assessing degradation and recovery pathways in lakes impacted by eutrophication using the sediment record

    Directory of Open Access Journals (Sweden)

    Helen eBennion

    2015-08-01

    Full Text Available Efforts to restore enriched lakes have increased yet there remains uncertainty about whether restoration targets can be achieved and over what timescale. Paleoecological techniques, principally diatom analyses, were used to examine the degree of impact and recovery in 12 European lakes subject to eutrophication and subsequent reduction in nutrient loading. Dissimilarity scores showed that all sites experienced progressive deviation from the reference sample (core bottom prior to nutrient reduction, and principal curves indicated gradual compositional change with enrichment. When additive models were applied to the latter, the changes were statistically significant in 9 of the 12 sites. Shifts in diatom composition following reduction in nutrient loading were more equivocal, with a reversal towards the reference flora seen only in four of the deep lakes and one of the shallow lakes. Of these, only two were significant (Lake Bled and Mjøsa. Alternative nutrient sources seem to explain the lack of apparent recovery in the other deep lakes. In three shallow lakes diatom assemblages were replaced by a community associated with lower productivity but not the one seen prior to enrichment. Internal loading and top down control may influence recovery in shallow lakes and climate change may have confounded recovery in several of the study sites. Hence, ecosystem recovery is not simply a reversal of the degradation pathway and may take several decades to complete or, for some lakes, may not take place at all. By assessing ecological change over a decadal to centennial timescale, the study highlights the important role that paleolimnology can play in establishing a benchmark against which managers can evaluate the degree to which their restoration efforts are successful.

  13. Parasitic Eukaryotes in a Meso-Eutrophic Coastal System with Marked Phaeocystis globosa Blooms

    Directory of Open Access Journals (Sweden)

    Urania Christaki

    2017-12-01

    Full Text Available This study explored the potential interactions and relations of the putative Symbiotic/Decomposer/Parasitic community (SymbDec with other taxa and predominant environmental parameters in the eastern English Channel (EEC over a 2.5 years period (32 sampling dates. The EEC is a meso-eutrophic coastal system portrayed by intense reoccurring patterns in plankton succession with blooms of the Haptophyte Phaeocystis globosa and abundant populations of colonial diatoms and dinoflagellate grazers before and after the bloom. The study of the V2-V3 hypervariable region of the 18S rRNA gene allowed an overview of the planktonic community, which consisted of 32 high-level taxonomic groups. Forty-two percent of the identified OTUs belonged to symbionts, decomposers or other putative parasitic taxa belonging mainly to Syndiniales (MALV—MArine ALveolates, Fungi, Cercozoa, Perkinsea, and others, most of which were plankton parasites. We examined the Local Similarity Analysis (LSA network of lag delayed correlations on the 142 most abundant OTUs (>0.1% of the total number of reads. LSA showed that 99 OTUs had highly significant connections, involving 26 OTUs characterized as potential parasites, and 2 decomposers. The parasitic network had “small world” characteristics, rendering the assemblage more robust to abiotic variations, but more exposed to the removal of highly associated taxa. The majority of the highly connected OTUs belonged to MALV, which were mainly connected with dinoflagellates, suggesting that it might play an important role on dinoflagellate top-down control. The bloom forming P. globosa was not observed in connection with parasitic OTUs in the network. Four environmental parameters (O2, N, T, and N/P were strongly connected with only 11 OTUs, while correlations between microbes dominated the network.

  14. River-Lake Mixing, Eutrophication, and Hypoxia in Green Bay, Lake Michigan

    Science.gov (United States)

    Klump, J. V.; LaBuhn, S.

    2014-12-01

    Despite being a freshwater system, Green Bay in Lake Michigan, has many estuarine-like characteristics, including water mass exchange and the mixing between riverine inflow and the open lake. The bay has experienced excessive nutrient loading for decades resulting in hyper-eutrophic conditions and extensive algal blooms. Combined with a restricted, estuarine like circulation, this has resulted in the reoccurrence of late summer "dead zones" and wide spread bottom water oxygen concentrations below water quality standards. The onset of hypoxia is clearly related to thermal stratification which, in Green Bay, arises both from direct atmospheric forcing, i.e. low winds, high air temperatures, and increased solar radiation, and from indirect atmospheric forcing that drives circulation patterns resulting in the southerly incursion of cooler Lake Michigan bottom waters onto highly reducing organic rich sediment deposits. This circulation pattern can re-stratify a well-mixed water column within hours, and can set up stable stratified water column conditions that persist for days to weeks during which time sediment oxygen demand rates are sufficient to completely deplete hypolimnetic oxygen. Modeling hypoxia, therefore, is somewhat more complex than in a system which is driven largely or solely by seasonal thermal fluctuations. Understanding both the general circulation and the onset and duration of stratification in the bay are essential to determining the potential for hypoxic conditions to improve or worsen, particularly in the face of climate change projections of warmer conditions, less ice cover, and an earlier summer. Using D and O-18 isotopes in water, Rn-222, and dissolved methane as tracers we examine the relationship between river/lake mixing, transport rates and oxygen depletion in an attempt to verify the spatial and temporal scales of hypoxia in the bay, and estimate the potential impact of future climate change projections.

  15. Effect of coastal eutrophication on heavy metal bioaccumulation and oral bioavailability in the razor clam, Sinonovacula constricta

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Tengxiu [College of Chemistry and Environment, Minnan Normal University, Zhangzhou 363000 (China); Li, Shunxing, E-mail: lishunxing@mnnu.edu.cn [College of Chemistry and Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology (China); Chen, Lihui [College of Chemistry and Environment, Minnan Normal University, Zhangzhou 363000 (China); Zheng, Fengying; Huang, Xu-Guang [College of Chemistry and Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology (China)

    2014-10-15

    Graphical abstract: - Highlights: • Razor clams are often exposed to coastal eutrophication. • The bioaccumulation of Fe, Ni, V, and As was promoted by eutrophication. • Bionic gastrointestinal tract was used for metal oral bioavailability assessment. • Eutrophication decreased oral bioavailability of Fe and Pb but enhanced for V. • The daily maximum allowable intakes are controlled by eutrophication levels. - Abstract: As traditional seafoods, the razor clams are widely distributed from tropical to temperate areas. Coastal razor clams are often exposed to eutrophication. Heavy metal contamination is critical for seafood safety. However, how eutrophication affects bioaccumulation and oral bioavailability of heavy metals in the razor clams is unknown. After a four-month field experimental cultivation, heavy metals (Fe, Cu, Ni, V, As, and Pb) could be bioaccumulated by the razor clams (Sinonovacula constricta) through exposure to metals present in water and sediments or in the food chain, and then transferred to human via consumption of razor clams. Bionic gastrointestinal digestion and monolayer liposome extraction are used for metal oral bioavailability (OBA) assessment. The influence of eutrophication on OBA is decreased for Fe and Pb and increased for V. A significant positive linear correlation was observed between the bioaccumulation factors of Fe, Ni, V, and As in razor clams and the coastal eutrophication. These results may be due to the effect of eutrophication on metal species transformation in coastal seawater and subcellular distribution in razor clams. The maximum allowable daily intakes of razor clams are controlled by eutrophication status and the concentration of affinity-liposome As in razor clams.

  16. Structural synthesis of linkages for quadruped bio-robot legs

    Science.gov (United States)

    Antonescu, O.; Robu, C.; Antonescu, P.

    2016-08-01

    The paper presents a few kinematic schemes of planar mechanisms with bars (linkages) used as part of the quadruped robot legs. The Dunshee linkage having only four elements as crank-rocker mechanism is analyzed. Further, the Klann linkage, which is accomplished by amplifying the crank-rocker mechanism with a dyadic kinematic chain, is also presented. More than that, the Jansen linkage, which is obtained by extending and amplifying the crank-rocker mechanism with two dyadic kinematic chains, is also analyzed. At the end of the paper, the authors present a novel linkage application consisting of a quadric kinematic chain.

  17. The linkage between childhood bullying behaviour and future offending.

    Science.gov (United States)

    Jiang, Depeng; Walsh, Margaret; Augimeri, Leena K

    2011-04-01

    To examine the linkage between bullying behaviour in early childhood and any subsequent contact with the criminal justice system. A Canadian sample (570 boys and 379 girls) was derived from clients who participated in the evidenced-based programme, SNAP (STOP NOW AND PLAN), between 2001 and 2009. A court order was obtained to access any criminal record data on participants. The Early Assessment Risk Lists (EARL-20B and EARL-21G) and the Child Behavior Checklist (CBCL) were used to identify level of risk and bullying behaviour. Outcome variables included age the child first came in contact with the criminal justice system and frequency. Logistic and Cox regression analyses indicate that the risk of onset of criminal offence for bullies was significantly higher than for non-bullies. The hazard of criminal offence for bullies is 1.9 times (95% CI: 1.1-3.2) than that of non-bullies. This holds true even when adjusted for age, gender and other risk factors. We found a strong linkage between bullying behaviour during childhood and subsequent criminal offending after the age of 12. Criminal convictions for bullies were nearly twice as high for non-bullies up to the child's 18th birthday. EARLs were effective in differentiating risk associated with bullying. Copyright © 2011 John Wiley & Sons, Ltd.

  18. A Node Linkage Approach for Sequential Pattern Mining

    Science.gov (United States)

    Navarro, Osvaldo; Cumplido, René; Villaseñor-Pineda, Luis; Feregrino-Uribe, Claudia; Carrasco-Ochoa, Jesús Ariel

    2014-01-01

    Sequential Pattern Mining is a widely addressed problem in data mining, with applications such as analyzing Web usage, examining purchase behavior, and text mining, among others. Nevertheless, with the dramatic increase in data volume, the current approaches prove inefficient when dealing with large input datasets, a large number of different symbols and low minimum supports. In this paper, we propose a new sequential pattern mining algorithm, which follows a pattern-growth scheme to discover sequential patterns. Unlike most pattern growth algorithms, our approach does not build a data structure to represent the input dataset, but instead accesses the required sequences through pseudo-projection databases, achieving better runtime and reducing memory requirements. Our algorithm traverses the search space in a depth-first fashion and only preserves in memory a pattern node linkage and the pseudo-projections required for the branch being explored at the time. Experimental results show that our new approach, the Node Linkage Depth-First Traversal algorithm (NLDFT), has better performance and scalability in comparison with state of the art algorithms. PMID:24933123

  19. Linkage studies on chromosome 22 in familial schizophrenia

    Energy Technology Data Exchange (ETDEWEB)

    Vallada, H.P.; Gill, M.; Sham, P. [Institute of Psychiatry, London (United Kingdom)] [and others

    1995-04-24

    As part of a systematic search for a major genetic locus for schizophrenia we have examined chromosome 22 using 14 highly polymorphic markers in 23 disease pedigrees. The markers were distributed at an average distance of 6.6 cM, covering 70-80% of the chromosome. We analyzed the data by the lod score method using five plausible genetic models ranging from dominant to recessive, after testing the power of our sample under the same genetic parameters. The most positive lod score found was 1.51 under a recessive model for the marker D22S278, which is insufficient to conclude linkage. However, an excess of shared alleles in affected siblings (P < .01) was found for both D22S278 and D22S283. For D22S278, the A statistic was equal to the lod score (1.51) and therefore did not provide additional evidence for linkage allowing for heterogeneity, but the Liang statistic was more significant (P = .002). Our results suggest the possibility that the region around D22S278 and D22S283 contains a gene which contributes to the etiology of schizophrenia. 60 refs., 1 fig., 5 tabs.

  20. Linkage of Pfeiffer syndrome to chromosome 8 centromere and evidence for genetic heterogeneity.

    Science.gov (United States)

    Robin, N H; Feldman, G J; Mitchell, H F; Lorenz, P; Wilroy, R S; Zackai, E H; Allanson, J E; Reich, E W; Pfeiffer, R A; Clarke, L A

    1994-12-01

    Pfeiffer syndrome (PS) is an autosomal dominant disorder characterized by craniosynostosis, midfacial hypoplasia, and broad thumbs and great toes. We examined 129 individuals from 11 families with PS and performed linkage studies using microsatellite markers spanning the entire genome. Strongest support for linkage was with DNA markers (D8S255, GATA8G08) from chromosome 8. Obligate crossovers exclude close linkage to this region in six families, and there was significant evidence for genetic heterogeneity. A multipoint lod score of 7.15 was obtained in five families. The 11 cM interval between D8S278 and D8S285 contains one gene for PS and also spans the centromere of chromosome 8.

  1. A teaching and communication tool based on DPSIR and LCIA indicator for marine eutrophication

    DEFF Research Database (Denmark)

    Cosme, Nuno Miguel Dias; Olsen, Stig Irving

    to understand D-R. The DPSIR approach was applied to the LCIA indicator for marine eutrophication to communicate sustainability assessment to graduate students. Broadly, this science-based educational example is useful to predict impacts, communicate knowledge, and support decisions. It assesses the high demand...

  2. Eutrophication management in surface waters using lanthanum modified bentonite: a review

    NARCIS (Netherlands)

    Copetti, D.; Finsterle, K.; Marziali, L.; Stefani, F.; Tartari, G.; Douglas, G.C.; Reitzel, K.; Spears, B.M.; Winfield, I.J.; Crosa, G.; Yasseri, S.; Lurling, M.F.L.L.W.

    2016-01-01

    This paper reviews the scientific knowledge on the use of a lanthanum modified bentonite (LMB) to manage eutrophication in surface water. The LMB has been applied in around 200 environments worldwide and it has undergone extensive testing at laboratory, mesocosm, and whole lake scales. The available

  3. Possible future effects of large-scale algae cultivation for biofuels on coastal eutrophication in Europe

    NARCIS (Netherlands)

    Blaas, H.; Kroeze, C.

    2014-01-01

    Biodiesel is increasingly considered as an alternative for fossil diesel. Biodiesel can be produced from rapeseed, palm, sunflower, soybean and algae. In this study, the consequences of large-scale production of biodiesel from micro-algae for eutrophication in four large European seas are analysed.

  4. Biomanipulation with quagga mussels (Dreissena rostriformis bugensis) to control harmful algal blooms in eutrophic urban ponds

    NARCIS (Netherlands)

    Waajen, Guido W. A. M.; Van Bruggen, Niek C. B.; Pires, L. Miguel Dionisio; Lengkeek, Wouter; Lurling, Miquel

    Many urban ponds in The Netherlands and other countries suffer from eutrophication, resulting in harmful algal blooms which are often dominated by cyanobacteria. A sufficient reduction of nutrients, as prerequisite to mitigate cyanobacterial blooms in urban ponds, is not always feasible. Water

  5. Biomanipulation with quagga mussels (Dreissena rostriformis bugensis) to control harmful algal blooms in eutrophic urban ponds

    NARCIS (Netherlands)

    Waajen, Guido W.A.M.; Bruggen, Van Niek C.B.; Pires, Miguel Dionisio L.; Lengkeek, Wouter; Lurling, Miguel

    2016-01-01

    Many urban ponds in The Netherlands and other countries suffer from eutrophication, resulting in harmful algal blooms which are often dominated by cyanobacteria. A sufficient reduction of nutrients, as prerequisite to mitigate cyanobacterial blooms in urban ponds, is not always feasible. Water

  6. Rising CO2 levels will intensify phytoplankton blooms in eutrophic and hypertrophic lakes

    NARCIS (Netherlands)

    Verspagen, J.M.H.; van de Waal, D.B.; Finke, J.F.; Visser, P.M.; van Donk, E.; Huisman, J.

    2014-01-01

    Harmful algal blooms threaten the water quality of many eutrophic and hypertrophic lakes and cause severe ecological and economic damage worldwide. Dense blooms often deplete the dissolved CO2 concentration and raise pH. Yet, quantitative prediction of the feedbacks between phytoplankton growth, CO2

  7. Ectomycorrhizal root development in wet Alder carr forests in response to desiccation and eutrophication

    NARCIS (Netherlands)

    Baar, J.; Bastiaans, T.; Coevering van de, M.A.; Roelofs, J.G.M.

    2002-01-01

    Effects of desiccation and eutrophication on ectomycorrhizal (ECM) root development in wet Alder carr forests in The Netherlands were studied. In northwestern Europe, wet Alder carr forests are found mostly in peatlands and along streams, forming an important component of wetland ecosystems. The

  8. Nitrogen inputs from agriculture: towards better assessments of eutrophication status in marine waters.

    Science.gov (United States)

    Andersen, Jesper H; Fossing, Henrik; Hansen, Jens W; Manscher, Ole H; Murray, Ciarán; Petersen, Ditte L J

    2014-11-01

    Nutrient enrichment of coastal marine waters caused by losses of nitrate (NO(3)(-)) from agriculture is an increasing global problem. In the European Union, the Nitrates Directive (ND) of 1991 was meant to be a cornerstone in reducing eutrophication effects in coastal waters downstream from intensively farmed catchments. Although reductions in losses of nitrate have been attained, very few Member States have yet been able to reduce eutrophication effects caused by inputs of NO(3)(-) from agriculture. We report trends in concentrations of NO(3)(-) and chlorophyll-a (Chl-a) in Danish coastal and open marine waters during the period from 1996 to 2011 together with an assessment of eutrophication status based on multiple indicators (e.g. nutrient concentrations, Chl-a, submerged aquatic vegetation and benthic macroinvertebrates). Despite decreasing concentrations of both NO(3)(-)and Chl-a, Danish coastal waters are not yet to be classified as 'unaffected by eutrophication'. In order to improve future pan-European evaluations of the effectiveness of the ND, we argue for the added value of including indicators and assessment principles from other European Directives, i.e. the Water Framework Directive and the Marine Strategy Framework Directive.

  9. A restoration-promoting integrated floating bed and its experimental performance in eutrophication remediation.

    Science.gov (United States)

    Guo, Yiming; Liu, Yunguo; Zeng, Guangming; Hu, Xinjiang; Li, Xin; Huang, Dawei; Liu, Yunqin; Yin, Yicheng

    2014-05-01

    Numerous studies on eutrophication remediation have mainly focused on purifying water first, then restoring submerged macrophytes. A restoration-promoting integrated floating bed (RPIFB) was designed to combine the processes of water purification and macrophyte restoration simultaneously. Two outdoor experiments were conducted to evaluate the ecological functions of the RPIFB. Trial 1 was conducted to compare the eutrophication purification among floating bed, gradual-submerging bed (GSB) and RPIFB technologies. The results illustrated that RPIFB has the best purification capacity. Removal efficiencies of RPIFB for TN, TP, NH(+)4-N, NO(-)3-N, CODCr, Chlorophyll-a and turbidity were 74.45%, 98.31%, 74.71%, 88.81%, 71.42%, 90.17% and 85%, respectively. In trial 2, influences of depth of GSB and photic area in RPIFB on biota were investigated. When the depth of GSB decreased and the photic area of RPIFB grew, the height of Potamogeton crispus Linn. increased, but the biomass of Canna indica Linn. was reduced. The mortalities of Misgurnus anguillicaudatus and Bellamya aeruginosa in each group were all less than 7%. All results indicated that when the RPIFB was embedded into the eutrophic water, the regime shift from phytoplankton-dominated to macrophyte-dominated state could be promoted. Thus, the RPIFB is a promising remediation technology for eutrophication and submerged macrophyte restoration. Copyright © 2014 The Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  10. Ocean acidification with (de)eutrophication will alter future phytoplankton growth and succession.

    Science.gov (United States)

    Flynn, Kevin J; Clark, Darren R; Mitra, Aditee; Fabian, Heiner; Hansen, Per J; Glibert, Patricia M; Wheeler, Glen L; Stoecker, Diane K; Blackford, Jerry C; Brownlee, Colin

    2015-04-07

    Human activity causes ocean acidification (OA) though the dissolution of anthropogenically generated CO2 into seawater, and eutrophication through the addition of inorganic nutrients. Eutrophication increases the phytoplankton biomass that can be supported during a bloom, and the resultant uptake of dissolved inorganic carbon during photosynthesis increases water-column pH (bloom-induced basification). This increased pH can adversely affect plankton growth. With OA, basification commences at a lower pH. Using experimental analyses of the growth of three contrasting phytoplankton under different pH scenarios, coupled with mathematical models describing growth and death as functions of pH and nutrient status, we show how different conditions of pH modify the scope for competitive interactions between phytoplankton species. We then use the models previously configured against experimental data to explore how the commencement of bloom-induced basification at lower pH with OA, and operating against a background of changing patterns in nutrient loads, may modify phytoplankton growth and competition. We conclude that OA and changed nutrient supply into shelf seas with eutrophication or de-eutrophication (the latter owing to pollution control) has clear scope to alter phytoplankton succession, thus affecting future trophic dynamics and impacting both biogeochemical cycling and fisheries.

  11. Unexpected Responses of autotrophs to nutrient loading: Influence of water residence time on eutrophication expression

    Science.gov (United States)

    Water residence time may critically influence the expression of estuarine eutrophication symptoms such as phytoplankton blooms, anoxia/hypoxia, build-up of organic matter, and altered community composition. While a conceptual model was developed in the late 1990’s; pioneer...

  12. Lack of eutrophication in a tallgrass prairie ecosystem over 27 years.

    Science.gov (United States)

    McLauchlan, Kendra K; Craine, Joseph M; Nippert, Jesse B; Ocheltree, Troy W

    2014-05-01

    Many North American grasslands are receiving atmospheric nitrogen (N) deposition at rates above what are considered critical eutrophication thresholds. Yet, potential changes in grassland function due to anthropogenic N deposition are poorly resolved, especially considering that other dynamic factors such as land use and precipitation can also affect N availability. To better understand whether elevated N deposition has altered ecosystem structure or function in North American grasslands, we analyzed a 27-year record of ecophysiological, community, and ecosystem metrics for an annually burned Kansas tallgrass prairie. Over this time, despite increasing rates of N deposition that are within the range of critical loads for grasslands, there was no evidence of eutrophication. Plant N concentrations did not increase, soil moisture did not decline, forb diversity did not decline, and the relative abundance of dominant grasses did not shift toward more eutrophic species. Neither aboveground primary productivity nor N availability to plants increased. The fates of deposited N in grasslands are still uncertain, and could include management losses through burning and grazing. However, evidence from this grassland indicates that eutrophication of North American grassland ecosystems is not an inevitable consequence of current levels of N deposition.

  13. Application of LANDSAT to the Surveillance of Lake Eutrophication in the Great Lakes Basin. Final Report.

    Science.gov (United States)

    Rogers, Robert H.

    This document reviews the process by which the cost benefits of using LANDSAT on an operational basis in the surveillance of lake eutrophication was established. The program identified the information needs of users conducting on-going water quality programs, transformed these needs into remote sensing requirements, produced LANDSAT maps and data…

  14. Bioavailability and preservation of organic phosphorus in freshwater sediments and its role in lake eutrophication

    Science.gov (United States)

    Lake eutrophication in China is a serious environmental concern, especially in lakes from the middle and lower reaches of Yangtze River region and Southwestern China Plateau. The dissolution of organic matter can result in release of phosphorus (P) from lake sediments and organic phosphate (Po) itse...

  15. Assessment of eutrophication in estuaries: Pressure-state-response and source apportionment

    Science.gov (United States)

    David Whitall; Suzanne Bricker

    2006-01-01

    The National Estuarine Eutrophication Assessment (NEEA) Update Program is a management oriented program designed to improve monitoring and assessment efforts through the development of type specific classification of estuaries that will allow improved assessment methods and development of analytical and research models and tools for managers which will help guide and...

  16. Influence of acidification and eutrophication on physiological functions of Conticribra weissflogii and Prorocentrum donghaiense.

    Science.gov (United States)

    Zheng, Feng-Ying; Tu, Teng-Xiu; Liu, Feng-Jiao; Huang, Xu-Guang; Li, Shun-Xing

    2016-12-01

    Eutrophication and acidification have been the most concerned environmental problems in coastal ecosystem. However, their combined effect on coastal ecosystem function was unknown. Both diatom (Conticribra weissflogii) and dinoflagellate (Prorocentrum donghaiense) are used as coastal algal model. Seven parameters were determined for physiological function assessment, including cell density, chlorophyll a (Chl a), protein, malonaldehyde (MDA), superoxide dismutase, carbonic anhydrase (CA), and nitrate reductase (NR). The influence of nitrate (N) and phosphate (P) on MDA and CA in C. weissflogii was significant, and that on Chl a and protein in P. donghaiense were also significant. However, the influence of acidification on physiological functions was not significant. The effect of acidification could be intensified by coastal eutrophication. More importantly, the coexist influence of acidification and eutrophication on CA, NR and protein in C. weissflogii and MDA in P. donghaiense was significant. Both NR activity and Chl a content in P. donghaiense were positively correlated to N and P concentration when pH were 7.9 and 7.8, respectively. With simultaneous worsening of acidification and eutrophication, the cell growth of P. Donghaiense was accelerated more obviously than C. weissflogii, i.e., dinoflagellate was more adaptable than diatom, thus algal species distribution and abundance could be changed. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Eutrophication monitoring for Lake Superior’s Chequamegon Bay before and after large summer storms

    Science.gov (United States)

    A priority for the Lake Superior CSMI was to identify susceptible nearshore eutrophication areas. We developed an integrated sampling design to collect baseline data for Lake Superior’s Chequamegon Bay to understand how nearshore physical processes and tributary loading rel...

  18. Fast eutrophication assessment for stormwater wet detention ponds via fuzzy probit regression analysis under uncertainty.

    Science.gov (United States)

    Tahsin, Subrina; Chang, Ni-Bin

    2016-02-01

    Stormwater wet detention ponds have been a commonly employed best management practice for stormwater management throughout the world for many years. In the past, the trophic state index values have been used to evaluate seasonal changes in water quality and rank lakes within a region or between several regions; yet, to date, there is no similar index for stormwater wet detention ponds. This study aimed to develop a new multivariate trophic state index (MTSI) suitable for conducting a rapid eutrophication assessment of stormwater wet detention ponds under uncertainty with respect to three typical physical and chemical properties. Six stormwater wet detention ponds in Florida were selected for demonstration of the new MTSI with respect to total phosphorus (TP), total nitrogen (TN), and Secchi disk depth (SDD) as cognitive assessment metrics to sense eutrophication potential collectively and inform the environmental impact holistically. Due to the involvement of multiple endogenous variables (i.e., TN, TP, and SDD) for the eutrophication assessment simultaneously under uncertainty, fuzzy synthetic evaluation was applied to first standardize and synchronize the sources of uncertainty in the decision analysis. The ordered probit regression model was then formulated for assessment based on the concept of MTSI with the inputs from the fuzzy synthetic evaluation. It is indicative that the severe eutrophication condition is present during fall, which might be due to frequent heavy summer storm events contributing to high-nutrient inputs in these six ponds.

  19. Approaches for integrated assessment of ecological and eutrophication status of surface waters in Nordic Countries

    DEFF Research Database (Denmark)

    Andersen, Jesper H.; Aroviita, Jukka; Carstensen, Jacob

    2016-01-01

    We review approaches and tools currently used in Nordic countries (Denmark, Finland, Norway and Sweden) for integrated assessment of ‘ecological status’ sensu the EU Water Framework Directive as well as assessment of ‘eutrophication status’ in coastal and marine waters. Integration principles...

  20. Setting critical nutrient values for ditches using the eutrophication model PCDitch

    NARCIS (Netherlands)

    Liere, van L.; Janse, J.H.; Arts, G.H.P.

    2007-01-01

    Critical nutrient loads to prevent duckweed dominance loads in polder ditches were assessed using the eutrophication model PCDitch. In this article the ecological target was set at 50% duckweed coverage. This may be very high for ditches with a nature function, but is not unreasonable for ditches in

  1. Assessment of possible solid-phase phosphate sorbents to mitigate eutrophication

    NARCIS (Netherlands)

    Mucci, Maíra; Maliaka, Valentini; Noyma, Natalia Pessoa; Marinho, Marcelo Manzi; Lürling, Miquel

    2018-01-01

    Managing eutrophication remains a challenge to water managers. Currently, the manipulation of biogeochemical processes (i.e., geo-engineering) by using phosphorus-adsorptive techniques has been recognized as an appropriate tool to manage the problem. The first step in finding potential mitigating

  2. The evolution of the eutrophication of the Palić Lake (Serbia ...

    African Journals Online (AJOL)

    Eutrophication is a world-wide environmental issue. The Palic Lake is a shallow lake typical for the Pannonian plain. The Lake itself was in a very bad condition during the late sixties of the last century; polluted and hypertrophic. Due to inadequate water quality, it was dried out in 1971 and re-established in 1977 and since ...

  3. Nitrogen Inputs from Agriculture: Towards Better Assessments of Eutrophication Status in Marine Waters

    National Research Council Canada - National Science Library

    Andersen, Jesper H; Fossing, Henrik; Hansen, Jens W; Manscher, Ole H; Murray, Ciarán; Petersen, Ditte L. J

    2014-01-01

    .... We report trends in concentrations of NO3 − and chlorophyll-a (Chl-a) in Danish coastal and open marine waters during the period from 1996 to 2011 together with an assessment of eutrophication status based on multiple indicators (e.g...

  4. Marine eutrophication impacts from present and future production of spring barley

    DEFF Research Database (Denmark)

    Cosme, Nuno Miguel Dias; Niero, Monia

    2015-01-01

    Environmental emissions of nitrogen (N) from agriculture surplus may enrich coastal waters and trigger marine eutrophication impacts. We estimated these impacts for spring barley production in Denmark, under present and future climatic conditions with double carbon dioxide concentration and 5 °C ...

  5. Modelling reduced coastal eutrophication with increased crop yields in Chinese agriculture

    NARCIS (Netherlands)

    Li, Ang A.; Strokal, Maryna M.; Bai, Zhaohai Z.H.; Kroeze, Carolien C.; Ma, Lin L.; Zhang, Fusuo F.S.

    2017-01-01

    Eutrophication is a serious problem in Chinese rivers and seas, largely caused by increased nitrogen (N) and phosphorus (P) losses from agriculture. Chinese agriculture is known to be nutrient inefficient. Previous studies showed that fertiliser use can be reduced while increasing yields in the

  6. Application of Water Quality Model of Jordan River to Evaluate Climate Change Effects on Eutrophication

    Science.gov (United States)

    Van Grouw, B.

    2016-12-01

    The Jordan River is a 51 mile long freshwater stream in Utah that provides drinking water to more than 50% of Utah's population. The various point and nonpoint sources introduce an excess of nutrients into the river. This excess induces eutrophication that results in an inhabitable environment for aquatic life is expected to be exacerbated due to climate change. Adaptive measures must be evaluated based on predictions of climate variation impacts on eutrophication and ecosystem processes in the Jordan River. A Water Quality Assessment Simulation Program (WASP) model was created to analyze the data results acquired from a Total Maximum Daily Load (TMDL) study conducted on the Jordan River. Eutrophication is modeled based on levels of phosphates and nitrates from point and nonpoint sources, temperature, and solar radiation. It will simulate the growth of phytoplankton and periphyton in the river. This model will be applied to assess how water quality in the Jordan River is affected by variations in timing and intensity of spring snowmelt and runoff during drought in the valley and the resulting effects on eutrophication in the river.

  7. Numerical modeling of the central Black Sea ecosystem functioning during the eutrophication phase

    NARCIS (Netherlands)

    Grégoire, M.; Raick, C.; Soetaert, K.E.R.

    2008-01-01

    Abstract A one-dimensional coupled physical–biogeochemical model has been developed to simulate the ecosystem of the central Black Sea at the end of the 1980s when eutrophication and invasion by gelatinous organisms seriously affected the stability and dynamics of the system. The physical model is

  8. Interactions between fishes and the structure of fish communities in Dutch shallow, eutrophic lakes

    NARCIS (Netherlands)

    Lammens, E.

    1986-01-01

    This thesis describes the structure of fish communities in Tjeukemeer (21 km 2) and some other surrounding very eutrophic lakes and emphasizes the interactions of the fishes with each other and their food organisms (predation and

  9. Are bacteria an important food source for rotifers in eutrophic lakes?

    NARCIS (Netherlands)

    Ooms-Wilms, A.L.

    1997-01-01

    In situ grazing measurements using fluorescent particles of 0.5, 2.4 and 6.3 mu m diameter in eutrophic Lake Loosdrecht (The Netherlands) showed that Anuraeopsis fissa, a small rotifer, filtered the smallest, bacteria sized particles as efficiently or more efficiently than the larger particles. In

  10. Viral ecology of a shallow eutrophic lake - Virus ecologie in een ondiep eutroof meer

    NARCIS (Netherlands)

    Tijdens, M.

    2007-01-01

    This thesis aims to give an insight into the ecology of the viral community in a shallow eutrophic lake. To achieve this, the population dynamics, diversity and control of the viral community in Lake Loosdrecht were studied, as well as the impact of the viral community on plankton mortality and

  11. Community structure of macrozoobenthic feeding guilds in responses to eutrophication in Jakarta Bay

    Directory of Open Access Journals (Sweden)

    AM AZBAS TAURUSMAN

    2010-07-01

    Full Text Available Taurusman AA (2010 Community structure of macrozoobenthic feeding guilds in responses to eutrophication in Jakarta Bay. Biodiversitas 11: 133-138. The group of benthic fauna which feed on the same food sources are classified as a feeding guild. The objective of the present study was to evaluate the distribution and composition of macrozoobenthic feeding guilds along gradient of organic enrichment (trophic states in Jakarta Bay. The result of the present study was shown that at the hypertrophic stations of the bay dominated by species of surface deposit feeding polychaetes such as, Dodecaceria sp., Cirratulus sp., Capitella sp., and Spionidae. The eutrophic zone of the bay was dominated by suspension feeding bivalves Mactra sp., Chione sp. The offshore area (mesotrophic zone showed a high diversity of species and feeding guilds compared to other areas. The patterns of feeding guilds in the mesotrophic zone indicated a higher stability of macrozoobenthos community, indicated by the presence of deep-deposit feeder (e.g. Acetes sp., surface deposit feeders (e.g. Prionospio sp., suspension feeders (e.g. Chione sp., and carnivores (e.g. Nepthys sp. in comparable proportions. The structure of macrozoobenthic feeding guilds in an eutrophic coastal water is positively related to the quantity and quality of organic matters (eutrophic states, and the capability of benthic species in adaptation to such environmental condition.

  12. Aquatic macrophyte community varies in urban reservoirs with different degrees of eutrophication

    Directory of Open Access Journals (Sweden)

    Suelen Cristina Alves da Silva

    2014-06-01

    Full Text Available AIM: Investigate spatial and temporal variation in the aquatic macrophyte community in four urban reservoirs located in Curitiba metropolitan region, Brazil. We tested the hypothesis that aquatic macrophyte community differ among reservoirs with different degrees of eutrophication. METHODS: The reservoirs selected ranged from oligotrophic/mesotrophic to eutrophic. Sampling occurred in October 2011, January 2012 and June 2012. Twelve aquatic macrophytes stands were sampled at each reservoir. Species were identified and the relative abundance of aquatic macrophytes was estimated. Differences among reservoirs and over sampling periods were analyzed: i through two‑way ANOVAs considering the stand extent (m and the stand biodiversity - species richness, evenness, Shannon-Wiener index and beta diversity (species variation along the aquatic macrophyte stand; and ii through PERMANOVA considering species composition. Indicator species that were characteristic for each reservoir were also identified. RESULTS: The aquatic macrophyte stand extent varied among reservoirs and over sampling periods. Species richness showed only temporal variation. On the other hand, evenness and Shannon-Wiener index varied only among reservoirs. The beta diversity of macrophyte stands did not vary among reservoirs or over time, meaning that species variability among aquatic macrophyte stands was independent of the stand extent and reservoir eutrophication. Community composition depended on the reservoir and sampling period. CONCLUSIONS: Our results support our initial expectation that reservoirs of different degrees of eutrophication have different aquatic macrophyte communities. As a consequence, each reservoir had particular indicator species. Therefore, monitoring and management efforts must be offered for each reservoir individually.

  13. Growth rate, protein:RNA ratio and stoichiometric homeostasis of submerged macrophytes under eutrophication stress

    OpenAIRE

    Xing W.; Shi Q.; Liu H.; Liu G.

    2016-01-01

    Growth rate hypothesis (GRH) and stoichiometric homeostasis of photoautotrophs have always been questioned. However, little is known about GRH and stoichiometric homeostasis of aquatic plants, especially submerged macrophytes. Therefore, we aim to test the GRH and explore stoichiometric homeostasis of four freshwater submerged macrophytes under eutrophication stress. At the single species level and the multi-species level, N:P ratios ...

  14. Eutrophication threatens Caribbean seagrasses – An example from Curaçao and Bonaire

    NARCIS (Netherlands)

    Govers, L.L.; Lamers, L.P.M.; Bouma, T.J.; de Brouwer, J.H.F.; van Katwijk, M.M.

    2014-01-01

    Seagrass beds are globally declining due to human activities in coastal areas. We here aimed to identify threats from eutrophication to the valuable seagrass beds of Curaçao and Bonaire in the Caribbean, which function as nursery habitats for commercial fish species. We documented surface- and

  15. Significant linkage at chromosome 19q for otitis media with effusion and/or recurrent otitis media (COME/ROM).

    Science.gov (United States)

    Chen, Wei-Min; Allen, E Kaitlynn; Mychaleckyj, Josyf C; Chen, Fang; Hou, Xuanlin; Rich, Stephen S; Daly, Kathleen A; Sale, Michèle M

    2011-09-26

    In previous analyses, we identified a region of chromosome 19 as harboring a susceptibility locus for chronic otitis media with effusion and/or recurrent otitis media (COME/ROM). Our aim was to further localize the linkage signal and ultimately identify the causative variant or variants. We followed up our previous linkage scan with dense SNP genotyping across in a 5 Mb region. A total of 607 individuals from 139 families, including 159 affected sib pairs and 62 second-degree affected relative pairs, were genotyped at 1,091 SNPs. We carried out a nonparametric linkage analysis, modeling marker-to-marker linkage disequilibrium. The maximum log of the odds (LOD) score increased to 3.75 (P = 1.6 × 10(-5)) at position 63.4 Mb, with a LOD-1 support interval between 61.6 Mb and 63.8 Mb, providing significant evidence of linkage between this region and COME/ROM. The support interval contains over 90 known genes, including several genes involved in the inflammasome protein complex, a key regulator of the innate immune response to harmful exogenous or endogenous stimuli. Parametric linkage analysis suggests that for a sib of an affected individual, the recurrence risk of COME/ROM due to this linkage region is twice the recurrence risk in the population. We examined potential associations between the SNPs genotyped in this region and COME/ROM, however none provided evidence for association. This study has refined the 19q region of linkage with COME/ROM, and association results suggest that the linkage signal may be due to rare variants.

  16. [Distribution of Chlorophyll-a and Eutrophication State in Tianchi Lake of Tianshan Mountains in Summer].

    Science.gov (United States)

    Wang, Bin; Ma, Jian; Wang, Yin-ya; Yin, Xiang-jiang

    2015-07-01

    From June to August in 2014, the distributions of chlorophyll-a (Chl-a) and correlations with environmental factors were investigated, the eutrophication status and causes were discussed in Tianchi Lake of Tianshan Mountains. The results showed that the Chl-a concentrations ranged from 2. 11 to 4. 06 µg. L -1 with a mean value of (2. 8 ± 0. 69) µg . L-1 in summer, the vertical distribution of Chl-a in different monitoring zones had a similar characteristic that the Chl-a concentration in epilimnionis (2-12 m) was higher than those at the surface (0-2 m) and hypolimnion (below 12 m). The Chl-a concentration had significant negative correlations with depth and conductivity, significant positive correlations with water temperature, pH value, the concentration of dissolved oxygen, the cell density of algae and TP, and less correlation with TN. The mean concentrations of TN and TP in Tianchi Lake in summer were 0.27 mg . L-1 and 0.035 mg. L-1 respectively, both of which exceeded the international standards of general eutrophic lakes. The modified Carlson trophic state index was used to assess the eutrophication status of Tianchi Lake, which is currently at a moderate eutrophication level. The reasons might be the increased nutrients attributed to soil erosion, and algae blooms due to the changes in the composition of hydrobios. Therefore, it is important to use ecological restoration and management to protect the water quality and surrounding vegetation, which may mitigate the risk of eutrophication in Tianchi Lake.

  17. Shifts in coastal fish communities: Is eutrophication always beneficial for sticklebacks?

    Science.gov (United States)

    Gagnon, Karine; Gräfnings, Max; Boström, Christoffer

    2017-11-01

    Following declines of predatory fish, mesopredators such as sticklebacks have been linked to shifts in coastal trophic networks through both top-down (preying on mesograzers and facilitating algal blooms) and bottom-up (benefitting from eutrophicated conditions) processes. Here, we tested whether the association between eutrophication effects (filamentous algae and turbidity) and sticklebacks held true in the Finnish Archipelago Sea where predatory fish populations have remained stable. If so, sticklebacks should be more abundant in the middle archipelago, where eutrophic conditions have led to increased turbidity, higher filamentous algal loads, and decreased cover of submerged aquatic vegetation (SAV), than in the outer archipelago, where environmental conditions are better. We measured the spatial and seasonal variation of sticklebacks (three-spined Gasterosteus aculeatus and nine-spined Pungitius pungitius) in middle and outer archipelago sites, as well as environmental variables potentially affecting their abundance. Adults and juveniles of both species were more abundant in the outer than middle archipelago. The outer archipelago was characterized by greater Secchi depth throughout the summer and higher SAV cover in late summer. Secchi depth was positively correlated with stickleback abundance of both species, while SAV cover was also positively correlated in late summer. Filamentous algal cover was high in both the middle and outer archipelago, but not consistently associated with stickleback abundance throughout the summer. While sticklebacks have been thought to both contribute to, and benefit from, eutrophication, our results instead suggest that the resulting environmental changes may have adverse effects on sticklebacks, especially if predators are present. This may lead them to shift their breeding grounds and spatial distribution to less eutrophicated areas where lower turbidity and the resulting increased availability of SAV provide refuge from

  18. Decline in growth of foraminifer Marginopora rossi under eutrophication and ocean acidification scenarios.

    Science.gov (United States)

    Reymond, Claire E; Lloyd, Alicia; Kline, David I; Dove, Sophie G; Pandolfi, John M

    2013-01-01

    The combination of global and local stressors is leading to a decline in coral reef health globally. In the case of eutrophication, increased concentrations of dissolved inorganic nitrogen (DIN) and phosphorus (DIP) are largely attributed to local land use changes. From the global perspective, increased atmospheric CO2 levels are not only contributing to global warming but also ocean acidification (OA). Both eutrophication and OA have serious implications for calcium carbonate production and dissolution among calcifying organisms. In particular, benthic foraminifera precipitate the most soluble form of mineral calcium carbonate (high-Mg calcite), potentially making them more sensitive to dissolution. In this study, a manipulative orthogonal two-factor experiment was conducted to test the effects of dissolved inorganic nutrients and OA on the growth, respiration and photophysiology of the large photosymbiont-bearing benthic foraminifer, Marginopora rossi. This study found the growth rate of M. rossi was inhibited by the interaction of eutrophication and acidification. The relationship between M. rossi and its photosymbionts became destabilized due to the photosymbiont's release from nutrient limitation in the nitrate-enriched treatment, as shown by an increase in zooxanthellae cells per host surface area. Foraminifers from the OA treatments had an increased amount of Chl a per cell, suggesting a greater potential to harvest light energy, however, there was no net benefit to the foraminifer growth. Overall, this study demonstrates that the impacts of OA and eutrophication are dose dependent and interactive. This research indicates an OA threshold at pH 7.6, alone or in combination with eutrophication, will lead to a decline in M. rossi calcification. The decline in foraminifera calcification associated with pollution and OA will have broad ecological implications across their ubiquitous range and suggests that without mitigation it could have serious implications

  19. [Nitrogen and phosphate pollution characteristics and eutrophication evaluation for typical urban landscape waters in Hefei City].

    Science.gov (United States)

    Li, Ru-Zhong; Liu, Ke-Feng; Qian, Jing; Yang, Ji-Wei; Zhang, Pian-Pian

    2014-05-01

    To understand the water environment regimes of the city-circling water system in Hefei City, six typical landscape waters were chosen to investigate pollution characteristics of nitrogen and phosphate and evaluate water eutrophication level according to the monitoring data of water physicochemical characteristics and chlorophyll content from September 2012 to July 2013. Study results showed that (1) the six waters mentioned above have been seriously polluted by nitrogen and phosphorus loadings, with the monthly mean values of total nitrogen (TN) and total phosphorus (TP) concentrations far exceeding the universally accepted threshold values of water eutrophication; (2) the nitrogen contents in the waters of Nanfeihe River, Heichiba and Yuhuatang scenic spots exhibited a markedly monthly variation, and both TP and PO(3-)(4)-P in Nanfeihe River showed a fluctuated characteristic with high concentrations while presenting a significant upward trend in Yuhuatang scenic spot; (3) the average values of TN/TP ratios for Yuhuatang and Heichiba scenic spots were 104.7 and 158.3, respectively, and the ratios for Baohe Park, Yinhe Park, Xiaoyaojin Park, and city segment of Nanfeihe River were 16.8, 18.7, 6.4 and 16.8, respectively, indicating that the scenic waters of Yuhuatang and Heichiba were phosphate-limited whereas Xiaoyaojin Park was nitrogen-limited; (4) all the six scenic waters were, in general, subsumed under just two broad categories, namely Hechiba scenic spot and Nanfeihe River, which were seriously polluted, and clustered together, and the others fall into the second class; and (5) water eutrophication appraisal result indicated that the six waters were all in the state of eutrophication, and could be arranged in the order of eutrophication level, Yinhe Park > Heichiba scenic spot > city segment of Nanfeihe River > Xiaoyaojin Park > Yuhuatang scenic spot > Baohe Park.

  20. Land-Use Legacies Are Important Determinants of Lake Eutrophication in the Anthropocene

    Science.gov (United States)

    Keatley, Bronwyn E.; Bennett, Elena M.; MacDonald, Graham K.; Taranu, Zofia E.; Gregory-Eaves, Irene

    2011-01-01

    Background A hallmark of the latter half of the 20th century is the widespread, rapid intensification of a variety of anthropogenically-driven environmental changes—a “Great Acceleration.” While there is evidence of a Great Acceleration in a variety of factors known to be linked to water quality degradation, such as conversion of land to agriculture and intensification of fertilizer use, it is not known whether there has been a similar acceleration of freshwater eutrophication. Methodology/Principal Findings Using quantitative reconstructions of diatom-inferred total phosphorus (DI-TP) as a proxy for lake trophic state, we synthesized results from 67 paleolimnological studies from across Europe and North America to evaluate whether most lakes showed a pattern of eutrophication with time and whether this trend was accelerated after 1945 CE, indicative of a Great Acceleration. We found that European lakes have experienced widespread increases in DI-TP over the 20th century and that 33% of these lakes show patterns consistent with a post-1945 CE Great Acceleration. In North America, the proportion of lakes that increased in DI-TP over time is much lower and only 9% exhibited a Great Acceleration of eutrophication. Conclusions/Significance The longer and more widespread history of anthropogenic influence in Europe, the leading cause for the relatively pervasive freshwater eutrophication, provides an important cautionary tale; our current path of intensive agriculture around the world may lead to an acceleration of eutrophication in downstream lakes that could take centuries from which to recover. PMID:21264341

  1. Seasonal changes of arsenic speciation in lake waters in relation to eutrophication

    Energy Technology Data Exchange (ETDEWEB)

    Hasegawa, H., E-mail: hhiroshi@t.kanazawa-u.ac.jp [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192 (Japan); Rahman, M. Azizur; Kitahara, K.; Itaya, Y.; Maki, T.; Ueda, K. [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa 920-1192 (Japan)

    2010-03-01

    In this study, the influence of eutrophication on arsenic speciation in lake waters was investigated. Surface water samples (n = 1-10) were collected from 18 lakes in Japan during July 2007 and February 2008. The lakes were classified into mesotrophic (7 lakes) and eutrophic (11 lakes) based on the total phosphate (T-P) and chlorophyll-a (Chl-a) concentrations in water column. Inorganic, methylated and ultraviolet-labile fractions of arsenic species were determined by combining hydride generation atomic absorption spectrometry with ultraviolet irradiation. Organoarsenicals (mainly methylated and ultraviolet-labile fractions) comprised 30-60% of the total arsenic in most lakes during summer. On the other hand, inorganic arsenic species (As(III + V)) dominates (about 60-85%) during winter. The occurrence of ultraviolet-labile fractions of arsenic was higher in eutrophic lakes than those in mesotrophic lakes in both seasons. The concentration of dimethyl arsenic (DMAA) was high in eutrophic lakes during winter; and in mesotrophic lakes during summer. The results suggest that the conversion of As(III + V) to more complicated organoarsenicals occurred frequently in eutrophic lakes compared to that in mesotrophic lakes, which is thought to be the influence of biological activity in the water column. The distribution of arsenic species were well correlated with phosphate concentrations than those of Chl-a. This might be due to the competitive uptake of As(V) and phosphate by phytoplankton. The organoarsenicals (OrgAs)/As(V) ratio was higher at low phosphate concentration indicating that conversion of As(V) to OrgAs species was more active in phosphate-exhausted lakes with high phytoplankton density.

  2. Carbon and nitrogen burial in a plateau lake during eutrophication and phytoplankton blooms.

    Science.gov (United States)

    Huang, Changchun; Zhang, Linlin; Li, Yunmei; Lin, Chen; Huang, Tao; Zhang, Mingli; Zhu, A-Xing; Yang, Hao; Wang, Xiaolei

    2017-11-06

    Organic carbon (OC) buried in lake sediment is an important component of the global carbon cycle. The impact of eutrophication on OC burial in lakes should be addressed due to worldwide lake eutrophication. Fourteen (210)Pb- and (137)Cs-dated sediment cores taken in Dianchi Lake (China) in August 2006 (seven cores) and July 2014 (seven cores) were analyzed to evaluate the response of the organic carbon accumulation rate (OCAR) to eutrophication and algal blooms over the past hundred years. The mean value of OCAR before eutrophication occurred in 1979, 16.62±7.53 (mean value±standard deviation), increased to 54.33±27.29gm(-2)yr(-1) after eutrophication. It further increased to 61.98±28.94gm(-2)yr(-1) after algal blooms occurred (1989). The accumulation rate of organic nitrogen (ONAR) is coupled with OCAR. The high loss rate of OC and organic nitrogen (ON) leads to a long-term burial efficiency of only 10% and 5% of OC and ON. However, this efficiency can still lead to an increase in OCAR by a factor of 4.55 during algal blooms in Dianchi Lake. Dianchi Lake stored 1.26±0.32 Tg carbon and 0.071±0.018 Tg nitrogen, including 0.94±0.23 Tg OC and 0.32±0.14 Tg inorganic carbon, 0.066±0.018 Tg ON, 0.002±0.001 Tg nitrate nitrogen (NO3-N) and 0.003±0.001 Tg ammonium nitrogen (NH4-N) between 1900 and 2012. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Differential record linkage by Hispanic ethnicity and age in linked mortality studies: implications for the epidemiologic paradox.

    Science.gov (United States)

    Lariscy, Joseph T

    2011-12-01

    This study examines how the linkage of surveys to death records differs for Hispanics and non-Hispanic Whites and how such differences affect estimates of ethnic differences in U.S. adult mortality. I use data from the 1989-2000 National Health Interview Survey (NHIS) linked to the National Death Index (NDI) through 2002. Analyses assess how match score and match class vary by ethnicity, nativity, and age and whether mortality hazard ratios are sensitive to shifts in match criteria. Linkage quality is lower for Hispanic and foreign-born adults than for non-Hispanic White and U.S.-born adults. Modification of the linkage criteria determine whether the Hispanic mortality advantage is observed among middle-aged adults. The accuracy of adult mortality estimates depends on the quality of the linkage between surveys and death records.

  4. Comparison of feeding habits and physical activity between eutrophic and overweight/obese children and adolescents: a cross sectional study.

    Science.gov (United States)

    Nogueira-de-Almeida, Carlos Alberto; Pires, Lara Aquino Ferreira; Miyasaka, Jordan; Bueno, Vanessa; Khouri, Juliana Mathias Netto; Ramos, Marianna Lorenzo S Ramos; Ceccato, Yara Cristina; Costa, Vivian; Maia Júnior, Francisco de Assis

    2015-01-01

    it is broadly accepted, but little explored, that obese children practice less physical activity and eat more. This study has the objective of comparing feeding habits and physical activity between eutrophic and overweight/obese children and adolescents. 126 students with ages ranging from 6 to 18 years were evaluated. Eutrophic and overweight/obese students were compared according to calorie intake, macro and micronutrients, prevalence of physical inactivity and ingestion of micronutrients. differences were observed in the amount of calories ingested per unit of BMI (eutrophic, 97.6, and overweight/obese, 70.5, p=0.0061), as well as in calcium intake (eutrophic, 546.2, and overweight/obese, 440.7, p=0.0366). Both groups presented sedentarism, as well as a high prevalence of micronutrient intake deficiency, especially calcium and vitamins A, E, and C, but with no difference observed between eutrophic and overweight/obese subjects. energy and macronutrients consumption, as well as physical activity, were similar between eutrophic and overweight/obese. Calcium intake was lower in the overweight/obese group and the ingestion of vitamin C was lower in the eutrophic group. These results demonstrate the importance of considering all etiologic factors that may lead to obesity, so that new strategies for prevention and control may be added to traditional interventions.

  5. A case study of an enhanced eutrophication model with stoichiometric zooplankton growth sub-model calibrated by Bayesian method.

    Science.gov (United States)

    Yang, Likun; Peng, Sen; Sun, Jingmei; Zhao, Xinhua; Li, Xia

    2016-05-01

    Urban lakes in China have suffered from severe eutrophication over the past several years, particularly those with relatively small areas and closed watersheds. Many efforts have been made to improve the understanding of eutrophication physiology with advanced mathematical models. However, several eutrophication models ignore zooplankton behavior and treat zooplankton as particles, which lead to the systematic errors. In this study, an eutrophication model was enhanced with a stoichiometric zooplankton growth sub-model that simulated the zooplankton predation process and the interplay among nitrogen, phosphorus, and oxygen cycles. A case study in which the Bayesian method was used to calibrate the enhanced eutrophication model parameters and to calculate the model simulation results was carried out in an urban lake in Tianjin, China. Finally, a water quality assessment was also conducted for eutrophication management. Our result suggests that (1) integration of the Bayesian method and the enhanced eutrophication model with a zooplankton feeding behavior sub-model can effectively depict the change in water quality and (2) the nutrients resulting from rainwater runoff laid the foundation for phytoplankton bloom.

  6. Comparison of feeding habits and physical activity between eutrophic and overweight/obese children and adolescents: a cross sectional study

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Nogueira-de-Almeida

    2015-06-01

    Full Text Available Summary Objective: it is broadly accepted, but little explored, that obese children practice less physical activity and eat more. This study has the objective of comparing feeding habits and physical activity between eutrophic and overweight/obese children and adolescents. Methods: 126 students with ages ranging from 6 to 18 years were evaluated. Eutrophic and overweight/obese students were compared according to calorie intake, macro and micronutrients, prevalence of physical inactivity and ingestion of micronutrients. Results: differences were observed in the amount of calories ingested per unit of BMI (eutrophic, 97.6, and overweight/obese, 70.5, p=0.0061, as well as in calcium intake (eutrophic, 546.2, and overweight/obese, 440.7, p=0.0366. Both groups presented sedentarism, as well as a high prevalence of micronutrient intake deficiency, especially calcium and vitamins A, E, and C, but with no difference observed between eutrophic and overweight/obese subjects. Conclusion: energy and macronutrients consumption, as well as physical activity, were similar between eutrophic and overweight/obese. Calcium intake was lower in the overweight/obese group and the ingestion of vitamin C was lower in the eutrophic group. These results demonstrate the importance of considering all etiologic factors that may lead to obesity, so that new strategies for prevention and control may be added to traditional interventions.

  7. Eutrophication trends inferred from hypolimnetic dissolved-oxygen dynamics within selected White River reservoirs, northern Arkansas-southern Missouri, 1974-94

    Science.gov (United States)

    Green, W.R.

    1996-01-01

    The White River Basin in northern Arkansas and southern Missouri contains four major reservoirs. Beaver, Table Rock, and Bull Shoals Lakes form a chain of reservoirs on the main stem of the White River. Norfork Lake is on the North Fork River, a tributary of the White River. Vertical water- column profiles of temperature and dissolved- oxygen concentrations have been collected monthly, in general, at sites near the dam of each reservoir since 1974. Hypolimnetic dissolved- oxygen dynamics of these reservoirs from 1974 through 1994 were examined based on the near-dam data and used to infer temporal changes in eutrophication. Regression models indicated that a positive relation existed between discharge through the dam during the stratification season and the areal hypolimnetic deficit. Temporal changes in the relative areal hypolimnetic oxygen deficit, a model that adjusts the areal hypolimnetic oxygen deficit to standard temperature and depth, showed a decreasing trend in Beaver Lake from 1974 through 1994, indicating that the level of eutrophication decreased. Little or no change in the relative areal hypolimnetic oxygen deficit occurred in Table Rock, Bull Shoals, or Norfork Lakes over the period of record. Temporal analysis of the residuals from the oxygen deficit-discharge model indicated that the oxygen deficit-discharge function changed over time in Beaver and Table Rock Lakes. There was little or no temporal trend in residuals of areal hypolimnetic oxygen deficit over the period of record for Bull Shoals and Norfork Lakes. Multiple regression using a time variable and discharge through the dam during the stratification season was examined for the four reservoirs. The slope coefficient of the time variable for both Beaver and Table Rock Lakes was negative, indicating that the temporal function driving the discharge related areal hypolimnetic oxygen deficit decreased over the period of record. This temporal function may be an expression of biological

  8. Ethnicity and the ethics of data linkage

    Directory of Open Access Journals (Sweden)

    Boyd Kenneth M

    2007-11-01

    Full Text Available Abstract Linking health data with census data on ethnicity has potential benefits for the health of ethnic minority groups. Ethical objections to linking these data however include concerns about informed consent and the possibility of the findings being misused against the interests of ethnic minority groups. While consent concerns may be allayed by procedures to safeguard anonymity and respect privacy, robust procedures to demonstrate public approval of data linkage also need to be devised. The possibility of findings being misused against the interests of ethnic minority groups may be diminished by informed and open public discussion in mature democracies, but remain a concern in the international context.

  9. LINKAGES FOR QUADRUPED BIO-ROBOT WALKING

    Directory of Open Access Journals (Sweden)

    Ovidiu ANTONESCU

    2015-12-01

    Full Text Available This paper analyses the Jansen mechanism. It then presents a few pictures of a mobile quadruped robot, which will help to describe how the robot moves. We take into consideration the kinematic scheme of the spatial mechanism with bars (spatial linkage, which is used for each of the four robot legs. Each leg mechanism is driven by two rotate brushless actuators that include a spur gear low-ratio transmission. By means of analyzing the kinematic scheme, the spatial mechanism mobility that operates in both horizontal and vertical plane is calculated

  10. Linkages over time between adolescents' relationships with parents and friends.

    Science.gov (United States)

    De Goede, Irene H A; Branje, Susan J T; Delsing, Marc J M H; Meeus, Wim H J

    2009-11-01

    This 5-wave longitudinal study examines linkages over time between adolescents' perceptions of relationships with parents and friends with respect to support, negative interaction, and power. A total of 575 early adolescents (54.1% boys) and 337 middle adolescents (43.3% boys) participated. Path analyses mainly showed bidirectional associations between adolescents' perceptions of parent-adolescent relationships and friendships with a predominantly stronger influence from parent-adolescent relationships to friendships than vice versa in early to middle adolescence and an equal mutual influence in middle to late adolescence. The findings support the theoretical ideas that perceptions of relationships with parents generalize to perceptions of relationships with friends and that relationship skills and principles of adolescent friendships generalize to relationships with parents. Furthermore, the results indicate that the influence of parents decreases, whereas the influence of friends increases, and that both social worlds become equally important and overlapping towards late adolescence.

  11. Viral linkage in HIV-1 seroconverters and their partners in an HIV-1 prevention clinical trial.

    Directory of Open Access Journals (Sweden)

    Mary S Campbell

    2011-03-01

    Full Text Available Characterization of viruses in HIV-1 transmission pairs will help identify biological determinants of infectiousness and evaluate candidate interventions to reduce transmission. Although HIV-1 sequencing is frequently used to substantiate linkage between newly HIV-1 infected individuals and their sexual partners in epidemiologic and forensic studies, viral sequencing is seldom applied in HIV-1 prevention trials. The Partners in Prevention HSV/HIV Transmission Study (ClinicalTrials.gov #NCT00194519 was a prospective randomized placebo-controlled trial that enrolled serodiscordant heterosexual couples to determine the efficacy of genital herpes suppression in reducing HIV-1 transmission; as part of the study analysis, HIV-1 sequences were examined for genetic linkage between seroconverters and their enrolled partners.We obtained partial consensus HIV-1 env and gag sequences from blood plasma for 151 transmission pairs and performed deep sequencing of env in some cases. We analyzed sequences with phylogenetic techniques and developed a Bayesian algorithm to evaluate the probability of linkage. For linkage, we required monophyletic clustering between enrolled partners' sequences and a Bayesian posterior probability of ≥ 50%. Adjudicators classified each seroconversion, finding 108 (71.5% linked, 40 (26.5% unlinked, and 3 (2.0% indeterminate transmissions, with linkage determined by consensus env sequencing in 91 (84%. Male seroconverters had a higher frequency of unlinked transmissions than female seroconverters. The likelihood of transmission from the enrolled partner was related to time on study, with increasing numbers of unlinked transmissions occurring after longer observation periods. Finally, baseline viral load was found to be significantly higher among linked transmitters.In this first use of HIV-1 sequencing to establish endpoints in a large clinical trial, more than one-fourth of transmissions were unlinked to the enrolled partner

  12. A Novel Flux Linkage Indirect Measurement for Switched Reluctance Motor

    Science.gov (United States)

    Li, Pang; Zhang, Lei; Yu, Yue

    2017-05-01

    This paper presents a indirect detection system of flux linkage characteristic of switched reluctance motor based on dsPACE, fixed rotor position by mechanical indexing for Static flux linkage detection, the phase windings is excited by the step voltage signal, the voltage and phase current are collected real -time, and calculate flux linkage. The advantages of the method is that the parameters are optimized by ControlDesk, the flux linkage detection model is built by Simulink, no writing program, simple, easy implementation. An 1.5kw three-phase 12/8 SRM experimental prototype was constructed, the detection results of the Static flux linkage and dynamic flux linkage verified its validity and feasibility.

  13. Methods for genetic linkage analysis using trisomies

    Energy Technology Data Exchange (ETDEWEB)

    Feingold, E.; Lamb, N.E.; Sherman, S.L. [Emory Univ., Atlanta, GA (United States)

    1994-09-01

    Certain genetic disorders (e.g. congenital cataracts, duodenal atresia) are rare in the general population, but more common in people with Down`s syndrome. We present a method for using individuals with trisomy 21 to map genes for such traits. Our methods are analogous to methods for mapping autosomal dominant traits using affected relative pairs by looking for markers with greater than expected identity-by-descent. In the trisomy case, one would take trisomic individuals and look for markers with greater than expected reduction to homozygosity in the chromosomes inherited form the non-disjoining parent. We present statistical methods for performing such a linkage analysis, including a test for linkage to a marker, a method for estimating the distance from the marker to the gene, a confidence interval for that distance, and methods for computing power and sample sizes. The methods are described in the context of gene-dosage model for the etiology of the disorder, but can be extended to other models. We also resolve some practical issues involved in implementing the methods, including how to use partially informative markers, how to test candidate genes, and how to handle the effect of reduced recombination associated with maternal meiosis I non-disjunction.

  14. SNP frequency, haplotype structure and linkage disequilibrium in elite maize inbred lines

    Directory of Open Access Journals (Sweden)

    Smith Oscar

    2002-10-01

    Full Text Available Abstract Background Recent studies of ancestral maize populations indicate that linkage disequilibrium tends to dissipate rapidly, sometimes within 100 bp. We set out to examine the linkage disequilibrium and diversity in maize elite inbred lines, which have been subject to population bottlenecks and intense selection by breeders. Such population events are expected to increase the amount of linkage disequilibrium, but reduce diversity. The results of this study will inform the design of genetic association studies. Results We examined the frequency and distribution of DNA polymorphisms at 18 maize genes in 36 maize inbreds, chosen to represent most of the genetic diversity in U.S. elite maize breeding pool. The frequency of nucleotide changes is high, on average one polymorphism per 31 bp in non-coding regions and 1 polymorphism per 124 bp in coding regions. Insertions and deletions are frequent in non-coding regions (1 per 85 bp, but rare in coding regions. A small number (2–8 of distinct and highly diverse haplotypes can be distinguished at all loci examined. Within genes, SNP loci comprising the haplotypes are in linkage disequilibrium with each other. Conclusions No decline of linkage disequilibrium within a few hundred base pairs was found in the elite maize germplasm. This finding, as well as the small number of haplotypes, relative to neutral expectation, is consistent with the effects of breeding-induced bottlenecks and selection on the elite germplasm pool. The genetic distance between haplotypes is large, indicative of an ancient gene pool and of possible interspecific hybridization events in maize ancestry.

  15. Handling linkage disequilibrium in qualitative trait linkage analysis using dense SNPs: a two-step strategy

    Directory of Open Access Journals (Sweden)

    Dupuis Josée

    2009-08-01

    Full Text Available Abstract Background In affected sibling pair linkage analysis, the presence of linkage disequilibrium (LD has been shown to lead to overestimation of the number of alleles shared identity-by-descent (IBD among sibling pairs when parents are ungenotyped. This inflation results in spurious evidence for linkage even when the markers and the disease locus are not linked. In our study, we first theoretically evaluate how inflation in IBD probabilities leads to overestimation of a nonparametric linkage (NPL statistic under the assumption of linkage equilibrium. Next, we propose a two-step processing strategy in order to systematically evaluate approaches to handle LD. Based on the observed inflation of expected logarithm of the odds ratio (LOD from our theoretical exploration, we implemented our proposed two-step processing strategy. Step 1 involves three techniques to filter a dense set of markers. In step 2, we use the selected subset of markers from step 1 and apply four different methods of handling LD among dense markers: 1 marker thinning (MT; 2 recursive elimination; 3 SNPLINK; and 4 LD modeling approach in MERLIN. We evaluate relative performance of each method through simulation. Results We observed LOD score inflation only when the parents were ungenotyped. For a given number of markers, all approaches evaluated for each type of LD threshold performed similarly; however, RE approach was the only one that eliminated the LOD score bias. Our simulation results indicate a reduction of approximately 75% to complete elimination of the LOD score inflation while maintaining the information content (IC when setting a tolerable squared correlation coefficient LD threshold (r2 above 0.3 for or 2 SNPs per cM using MT. Conclusion We have established a theoretical basis of how inflated IBD information among dense markers overestimates a NPL statistic. The two-step processing strategy serves as a useful framework to systematically evaluate relative

  16. Linkage among School Performance, Housing Prices, and Residential Mobility

    National Research Council Canada - National Science Library

    Yoojin Yi; Euijune Kim; Eunjin Choi

    2017-01-01

    ... of the household, especially under rigid geographic school assignment. This paper identifies multilateral linkages among academic performance of elementary school, housing prices, and residential mobility in Seoul...

  17. Linking climate change mitigation and coastal eutrophication management through biogas technology: Evidence from a new Danish bioenergy concept.

    Science.gov (United States)

    Kaspersen, Bjarke Stoltze; Christensen, Thomas Budde; Fredenslund, Anders Michael; Møller, Henrik Bjarne; Butts, Michael Brian; Jensen, Niels H; Kjaer, Tyge

    2016-01-15

    The interest in sustainable bioenergy solutions has gained great importance in Europe due to the need to reduce GHG emissions and to meet environmental policy targets, not least for the protection of groundwater and surface water quality. In the Municipality of Solrød in Denmark, a novel bioenergy concept for anaerobic co-digestion of food industry residues, manure and beach-cast seaweed has been developed and tested in order to quantify the potential for synergies between climate change mitigation and coastal eutrophication management in the Køge Bay catchment. The biogas plant, currently under construction, was designed to handle an annual input of up to 200,000 t of biomass based on four main fractions: pectin wastes, carrageenan wastes, manure and beach-cast seaweed. This paper describes how this bioenergy concept can contribute to strengthening the linkages between climate change mitigation strategies and Water Framework Directive (WFD) action planning. Our assessments of the projected biogas plant indicate an annual reduction of GHG emissions of approx. 40,000 t CO2 equivalents, corresponding to approx. 1/3 of current total GHG emissions in the Municipality of Solrød. In addition, nitrogen and phosphorous loads to Køge Bay are estimated to be reduced by approx. 63 t yr.(-1) and 9 tyr.(-1), respectively, contributing to the achievement of more than 70% of the nutrient reduction target set for Køge Bay in the first WFD river basin management plan. This study shows that anaerobic co-digestion of the specific food industry residues, pig manure and beach-cast seaweed is feasible and that there is a very significant, cost-effective GHG and nutrient loading mitigation potential for this bioenergy concept. Our research demonstrates how an integrated planning process where considerations about the total environment are integrated into the design and decision processes can support the development of this kind of holistic bioenergy solutions. Copyright © 2015

  18. Long-term eutrophication prompts tradeoffs in nitrous oxide and methane emission in a New England salt marsh

    Science.gov (United States)

    Eutrophication is a common problem facing urban estuaries and may stimulate changes in microtopography, plant communities, and microbial processes that drive greenhouse gas (GHG) fluxes. Since coastal wetlands are known to sequester abundant carbon and GHGs relative to terrestri...

  19. Patterns in nutrient limitation and chlorophyll a along an anthropogenic eutrophication gradient in French Mediterranean coastal lagoons

    National Research Council Canada - National Science Library

    Souchu, Philippe; Bec, Beatrice; Smith, Val H; Laugier, Thierry; Fiandrino, Annie; Benau, Laurent; Orsoni, Valerie; Collos, Yves; Vaquer, Andre

    2010-01-01

    A cross-ecosystem comparison of data obtained from 20 French Mediterranean lagoons with contrasting eutrophication status provided the basis for investigating the variables that best predict chlorophyll a (Chl...

  20. Effects of elevated CO2 on phytoplankton during a mesocosm experiment in the southern eutrophicated coastal water of China

    National Research Council Canada - National Science Library

    Xin Liu; Yan Li; Yaping Wu; Bangqin Huang; Minhan Dai; Feixue Fu; David A Hutchins; Kunshan Gao

    2017-01-01

    .... Here, we report the first mesocosm CO2 perturbation study in a eutrophic subtropical bay during summer by investigating the effect of rising CO2 on a model artificial community consisting of well...

  1. Interacting effects of sulphate pollution, sulphide toxicity and eutrophication on vegetation development in fens: a mesocosm experiment.

    Science.gov (United States)

    Geurts, Jeroen J M; Sarneel, Judith M; Willers, Bart J C; Roelofs, Jan G M; Verhoeven, Jos T A; Lamers, Leon P M

    2009-07-01

    Both eutrophication and SO4 pollution can lead to higher availability of nutrients and potentially toxic compounds in wetlands. To unravel the interaction between the level of eutrophication and toxicity at species and community level, effects of SO4 were tested in nutrient-poor and nutrient-rich fen mesocosms. Biomass production of aquatic and semi-aquatic macrophytes and colonization of the water layer increased after fertilization, leading to dominance of highly competitive species. SO4 addition increased alkalinity and sulphide concentrations, leading to decomposition and additional eutrophication. SO4 pollution and concomitant sulphide production considerably reduced biomass production and colonization, but macrophytes were less vulnerable in fertilized conditions. The experiment shows that competition between species, vegetation succession and terrestrialization are not only influenced by nutrient availability, but also by toxicity, which strongly interacts with the level of eutrophication. This implies that previously neutralized toxicity effects in eutrophied fens may appear after nutrient reduction measures have been taken.

  2. Modelling the influence of changing climate in present and future marine eutrophication impacts from spring barley production

    DEFF Research Database (Denmark)

    Cosme, Nuno Miguel Dias; Niero, Monia

    2017-01-01

    of different normalisation references when comparing future Life Cycle Assessment (LCA) scenarios with current production systems. A parameterised characterisation model was developed to gauge the influence of future climatic-driven pressures on the marine eutrophication impact pathway. Spatial differentiation...

  3. Eutrophication, risk management and sustainability. The perceptions of different stakeholders in the northern Baltic Sea.

    Science.gov (United States)

    Lundberg, Cecilia

    2013-01-15

    The environmental condition of the Baltic Sea is not only of concern for natural scientists. The awareness of the deteriorating state of the ecosystem has become an issue of interdisciplinary interest, and the amount of organizations with the marine environment and ecosystem health on the agenda is large. To present holistic and sustainable solutions and results of the actions taken, an active cooperation between all stakeholder groups and levels are needed. How different stakeholders in the northern Baltic Sea perceive the structures and assessments of the eutrophication were analyzed by semi-structured interviews with 17 stakeholders representing authorities, scientists, NGOs and national interest organizations. The focus was the view of the governance structures, risk assessment, management and communication. There was an overall consensus that eutrophication is a serious problem. Still variations in the opinions both within and between the stakeholder groups were seen. The scientists were most divergent from the rest. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Responses of primary production, leaf litter decomposition and associated communities to stream eutrophication.

    Science.gov (United States)

    Dunck, Bárbara; Lima-Fernandes, Eva; Cássio, Fernanda; Cunha, Ana; Rodrigues, Liliana; Pascoal, Cláudia

    2015-07-01

    We assessed the eutrophication effects on leaf litter decomposition and primary production, and on periphytic algae, fungi and invertebrates. According to the subsidy-stress model, we expected that when algae and decomposers were nutrient limited, their activity and diversity would increase at moderate levels of nutrient enrichment, but decrease at high levels of nutrients, because eutrophication would lead to the presence of other stressors and overwhelm the subsidy effect. Chestnut leaves (Castanea sativa Mill) were enclosed in mesh bags and immersed in five streams of the Ave River basin (northwest Portugal) to assess leaf decomposition and colonization by invertebrates and fungi. In parallel, polyethylene slides were attached to the mesh bags to allow colonization by algae and to assess primary production. Communities of periphytic algae and decomposers discriminated the streams according to the trophic state. Primary production decomposition and biodiversity were lower in streams at both ends of the trophic gradient. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Eutrophication will increase during the 21st century as a result of precipitation changes.

    Science.gov (United States)

    Sinha, E; Michalak, A M; Balaji, V

    2017-07-28

    Eutrophication, or excessive nutrient enrichment, threatens water resources across the globe. We show that climate change-induced precipitation changes alone will substantially increase (19 ± 14%) riverine total nitrogen loading within the continental United States by the end of the century for the "business-as-usual" scenario. The impacts, driven by projected increases in both total and extreme precipitation, will be especially strong for the Northeast and the corn belt of the United States. Offsetting this increase would require a 33 ± 24% reduction in nitrogen inputs, representing a massive management challenge. Globally, changes in precipitation are especially likely to also exacerbate eutrophication in India, China, and Southeast Asia. It is therefore imperative that water quality management strategies account for the impact of projected future changes in precipitation on nitrogen loading. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  6. Eutrophication affects the resistance of fucoids to an introduced alga spread.

    Science.gov (United States)

    Luigi, Piazzi; Giulia, Ceccherelli

    2017-08-01

    This study investigates whether eutrophication can affect the capacity of the canopy alga Cystoseira brachycarpa to impede or limit the spread of the introduced species Caulerpa cylindracea. By means of a manipulative field study (16 months long), the effects of nutrient enrichment and C. cylindracea removal were tested on the canopy-alga and the associated macroalgal community. Results highlighted deep changes through time due to nutrient enrichment, as C. brachycarpa decreased and Halopteris scoparia increased in cover. Furthermore, C. brachycarpa was also affected by the presence of the introduced species Caulerpa cylindracea which, in turn, was found significantly advantaged by nutrient enrichment. Overall, our findings suggest that eutrophication can drive the substitution of Cystoseira with H. scoparia, leading to the shift from canopy to opportunistic species, which are unable to avoid the spread of C. cylindracea. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Resting cysts of freshwater dinoflagellates in southeastern Georgian Bay (Lake Huron) as proxies of cultural eutrophication

    DEFF Research Database (Denmark)

    McCarthy, Francine M.G.; Mertens, Kenneth Neil; Ellegaard, Marianne

    2011-01-01

    in the relative abundances of these two cyst morphotypes were attributed primarily to cultural eutrophication related to land-use changes around Severn Sound over the last six centuries. Cysts of Peridinium willei, a cosmopolitan dinoflagellate species that occurs in a broad range of temperature, pH and nutrient...... conditions, comprise 60–74% of the cysts identified in Ambrosia (ragweed)-rich sediments in the upper 20 cm of a gravity core taken from Honey Harbour. Euro-Canadian settlement and land-clearing that began in the Midland-Penetanguishene region around A.D. 1840 are evident in the increase in Ambrosia (ragweed...... (~ 700 to ~ 150 yBP) is attributed to earlier land-clearing by the Wendat (“Huron”), who practiced agriculture in the Penetanguishene peninsula between ~ A.D. 1450–1650. The cysts of these freshwater dinoflagellates thus appear to be sensitive to cultural eutrophication....

  8. Comprehensive Study Of Duckweed Cultivation And Growth Conditions Under Controlled Eutrophication

    Directory of Open Access Journals (Sweden)

    Bartošová Alica

    2015-06-01

    Full Text Available The paper discussed the issue of eutrophication. The most conspicuous effect of eutrophication is the creation of dense blooms of noxious, foul-smelling phytoplankton that reduce water clarity and harm water quality. Nutrient concentration, temperature and pH of the water largely influence the growth rate and composition of duckweed in general, but it can be said that the temperature and solar irradiation are the most important factors. In order to compare the rate of biomass increase of duckweed biomass in natural conditions and in a laboratory grown sample was analysed by spectrophotometric methods in UV/VIS region (Spectrophotometer GENESYSTM for the selected nutrients such as ammonium, ammonium nitrogen, nitrite, nitrate, and phosphate.

  9. Comprehensive Study Of Duckweed Cultivation And Growth Conditions Under Controlled Eutrophication

    Science.gov (United States)

    Bartošová, Alica; Sirotiak, Maroš; Fiala, Jozef

    2015-06-01

    The paper discussed the issue of eutrophication. The most conspicuous effect of eutrophication is the creation of dense blooms of noxious, foul-smelling phytoplankton that reduce water clarity and harm water quality. Nutrient concentration, temperature and pH of the water largely influence the growth rate and composition of duckweed in general, but it can be said that the temperature and solar irradiation are the most important factors. In order to compare the rate of biomass increase of duckweed biomass in natural conditions and in a laboratory grown sample was analysed by spectrophotometric methods in UV/VIS region (Spectrophotometer GENESYSTM) for the selected nutrients such as ammonium, ammonium nitrogen, nitrite, nitrate, and phosphate.

  10. Effect of low temperature on eutrophicated waterbody restoration by Spirodela polyrhiza.

    Science.gov (United States)

    Song, Guanling; Hou, Wenhua; Wang, Qunhui; Wang, Jianlong; Jin, Xiangcan

    2006-10-01

    Spirodela polyrhiza exposed to low temperature was investigated to study the possible application for recovering eutrophicated waterbody at 10-12 degrees C. The cell growth and enzymatic resistance to oxidative stress were compared with that grown at optimum temperature (26-28 degrees C). The frond number, fresh weight, soluble protein, chlorophyll, carrot pigment, root length, peroxidase (POD), catalase (CAT), superoxide dismutase (SOD) and malondialdehyde (MDA) were measured. The results demonstrated that the cell growth, the synthesis and absorption ability decreased and the protective enzymes increased. S. polyrhiza encountered seriously oxidative damage at such low temperature condition, and it was not suitable for recovering the eutrophicated natural waterbody at low temperature of 10-12 degrees C.

  11. Reproductive Allocation in Three Macrophyte Species from Different Lakes with Variable Eutrophic Conditions.

    Directory of Open Access Journals (Sweden)

    Tao Wan

    Full Text Available Reproductive allocation is a key process in the plant life cycle and aquatic plants exhibit great diversity in their reproductive systems. In the present study, we conduct a field investigation of three aquatic macrophytes: Stuckenia pectinata, Myriophyllum spicatum, and Potamogeton perfoliatus. Our results showed that widespread species, including S. pectinata and M. spicatum had greater plasticity in their allocation patterns in the form of increased sexual and asexual reproduction, and greater potential to set seeds and increase fitness in more eutrophic environments. P. perfoliatus also exhibited a capacity to adopt varied sexual reproductive strategies such as setting more offspring for the future, although only in clear conditions with low nutrient levels. Our results establish strategies and mechanisms of some species for tolerating and surviving in varied eutrophic lake conditions.

  12. [Effects of light on submerged macrophytes in eutrophic water: research progress].

    Science.gov (United States)

    Li-Sha, Zou; Ze-Yu, Nie; Xiao-Yan, Yao; Ji-Yan, Shi

    2013-07-01

    The restoration of submerged macrophytes is the key to remediate eutrophic water and maintain the health of aquatic ecosystem, while light is the main limiting factor. This paper summarized the factors affecting the light extinction in water and the mechanisms of light intensity affecting the physiology of submerged macrophytes, with the focuses on the metabolic mechanisms of carbon, nitrogen, and phosphorus, the responses of antioxidant enzyme system, and the feedbacks of pigment composition and concentration in the common submerged macrophytes under low light stress. Several engineering techniques applied in the ecological restoration of submerged macrophytes were presented, and the framework of the restoration of submerged macrophytes in eutrophic water was proposed. Some problems in current research and several suggestions on future research were addressed, which could help the related research and engineering practices.

  13. [Macrophytes from some high Andean lakes of Ecuador and their low potential as bioindicators of eutrophication].

    Science.gov (United States)

    Kiersch, Benjamin; Mühleck, Ralf; Gunkel, Günter

    2004-12-01

    The occurrence of macrophyte in three high Andean lakes of Ecuador, Lago San Pablo, Laguna La Mica and Lago Cuicocha was recorded in 5-9 transects per lake. The first two lakes are eutrophic, the third is an extremely oligotrophic caldera lake. The dominant species in eutrophic lakes are Ceratophyllum demersum, Myriophyllum quitense, Polamogeton illinoensis, P. striatus and Elodea matthewsii. In the oligotrophic lake P. pectinatus, P. illinoensis, and the Characeae Chara rusbyana, Ch. globularis and Nitella acuminata occur. The maximum depth of the macrophyte's presence can be used as an indicator of the trophic state, ranging from about 5 m in Mica to 35 m in Cuicocha. The bioindication value of the macrophyte species in these high Andean lakes is low, because few species occur and because some of them are not specific to environmental conditions.

  14. Atmospheric Nitrogen Deposition: An increasingly Important Source of "new" Nitrogen Supporting Coastal Eutrophication

    Science.gov (United States)

    Paerl, H. W.; Whitall, D. R.; Dennis, R. L.

    2004-12-01

    Atmospheric deposition of nitrogen (AD-N) to the North Atlantic Ocean (NAO) basin arises from diverse pollution sources in North America and Western Europe; these sources have increased by 5 to10 fold since the Industrial Revolution, agricultural expansion and urbanization in the NAO airshed and continue to increase in both geographic and depositional magnitudes. Based on recent estimates, AD-N flux (11.2 Tg N per year) accounts for 46-57 per cent of the total new or externally-supplied anthropogenic N flux to the NAO. In US estuarine and coastal waters, from 10 to over 40 per cent of new N loading is attributed to AD-N; estimates for North Carolina's Albemarle-Pamlico Sound system range from 20 to over 30 per cent. In developing regions of the world, AD-N is one of the most rapidly expanding sources of new N. AD-N has been linked to eutrophication in N-sensitive coastal waters. In North Carolina, N deposition has increased since the 1960's as a result of urbanization (chiefly NOx) and more recently agricultural growth (NH4+ and organic N). In particular, rapidly-expanding livestock operations have led to increases in the generation of N-enriched wastes and manures; a substantial proportion (30- >70 per cent) of which may be emitted as NH3 gas. Recent growth and intensification of animal operations in the midwest and coastal regions (e.g., Mid-Atlantic coastal plain) have been linked to increasing amounts of NH4+ deposition, according to a 2 decadal analysis of the National Acid Deposition Program (NADP) network. The impacts of both increasing amounts and altered chemical composition of AD-N are being examined in the N-limited, eutrophying (i.e., expanding algal blooms, hypoxia and anoxia) Neuse River Estuary, Pamlico Sound and coastal waters of North Carolina. Because of its relatively large contribution to total new N loading and potential biogeochemical and ecological importance in N sensitive waters, AD-N requires attention from air/watershed nutrient budgeting

  15. Historical eutrophication in a river-estuary complex in mid-coast Maine.

    Science.gov (United States)

    Köster, Dörte; Lichter, John; Lea, Peter D; Nurse, Andrea

    2007-04-01

    European settlement of New England brought about a novel disturbance regime that impacted rivers and estuaries through overfishing, deforestation, dams, and water pollution. The negative consequences of these activities intensified with industrialization in the 19th and 20th centuries, often resulting in ecosystem degradation. Since environmental legislation was implemented in the 1970s, improvement in water quality has been tangible and widespread; however, ecological recovery can require substantial amounts of time and may never be complete. To document the natural baseline conditions and investigate the recovery of a severely degraded river-estuary complex in mid-coast Maine, we examined diatoms, pollen, total organic carbon, total nitrogen, stable isotopes, total phosphorus, biogenic silica, and trace metals in intertidal sediments and established a chronology with 14C, 210Pb, and indicator pollen horizons. Both climate variability and human effects were evident in the sedimentary record of Merrymeeting Bay, the freshwater tidal portion of the Kennebec estuary. Natural climate variability was apparent in an episode of high sedimentation and altered diatom abundance during the 12th and 13th centuries and in changing pollen abundances between the 16th and 19th centuries, indicative of regional cooling. During the 18th century, colonial land clearance began an era of high sedimentation and eutrophication that strongly intensified with industrialization during the late 19th and 20th centuries. Improvements in water quality over the past 30 years in response to environmental regulation had little effect on ecosystem recovery as represented by the sedimentary record. Diatom composition and productivity and high fluxes of organic C, total P, and biogenic Si in recent sediments indicate that rates of nutrient loading remain high. These environmental proxies imply that aquatic productivity in Merrymeeting Bay was originally nutrient limited and water clarity high

  16. Effects of land use changes on eutrophication indicators in five coastal lagoons of the Southwestern Atlantic Ocean

    Science.gov (United States)

    Rodríguez-Gallego, Lorena; Achkar, Marcel; Defeo, Omar; Vidal, Leticia; Meerhoff, Erika; Conde, Daniel

    2017-03-01

    Five catchment areas in Uruguay were selected to conduct a nutrient exportation analysis and to evaluate the effects of current land use on the eutrophication of coastal lagoons. Satellite images and national agriculture censuses were used for a quantitative analysis of land use changes from 1974 to 2005, and a nutrient export coefficient approximation was used to determine long-term changes in annual loads. Several eutrophication indicators (water, sediment and autotrophic communities) were assessed seasonally in the lagoon basins during 2005 and 2006. The areal annual load of nutrients exported to the lagoons increased over time. Population and extensive livestock ranching were the most important nutrient sources, while agriculture is increasing in importance. Buffer effects of riparian forests on eutrophication indicators were observed in contrast to the wetlands surrounding the lagoons, which seem to be acting as a source of nutrients. Catchment size was inversely related to most eutrophication indicators. Afforestation and agriculture were found not to directly impact eutrophication indicators, however, catchments with larger agricultural areas showed higher concentrations of suspended solids, which may indicate the export of particulate nutrients. Salinity was inversely related to most eutrophication indicators, suggesting that the manipulation of the sand bar of the lagoons is a critical management issue. Sediment-related eutrophication indicators were more sensitive to changes in land uses and covers, in contrast with the more variable water column indicators, suggesting their potential use as enduring indicators. This research provides a rapid and integral assessment for qualitatively linking catchment changes with eutrophication indicators in coastal environments, which can easily be replicated to track pollutants in locations that lack standardized monitoring programs needed for more complex catchment modeling approaches.

  17. The role of fish communities in the eutrophication of Shallow Lakes

    OpenAIRE

    Blanco Lanza, Sa??l

    2010-01-01

    P.41-66 The progressive anthropogenic eutrophication, the uncontrolled introduction of exotic fish species, and the lack of conservation and management strategies are highlighted as the main causes explaining the long-term changes in water biological quality in freshwater ponds and their surrounding aquatic ecosystems worldwide. Experimental evidence shows that fish direct and indirect effects on lake food web lead to algal growths and increased turbidity and nutrients concentration in fis...

  18. Eutrophication and macroalgal blooms in temperate and tropical coastal waters: nutrient enrichment experiments with Ulva spp.

    OpenAIRE

    Teichberg, Mirta; Fox, Sophia E; Olsen, Ylva S.; Valiela, Ivan; Martinetto, Paulina; Iribarne, Oscar; Muto, Elizabeti Yuriko; PETTI, MONICA A.V.; Corbisier, Tha?s N; Soto-Jim?nez, Mart?n; P?ez-Osuna, Federico; Castro, Paula; Freitas, Helena; Zitelli, Andreina; Cardinaletti, Massimo

    2010-01-01

    Receiving coastal waters and estuaries are among the most nutrient-enriched environments on earth, and one of the symptoms of the resulting eutrophication is the proliferation of opportunistic, fast-growing marine seaweeds. Here, we used a widespread macroalga often involved in blooms, Ulva spp., to investigate how supply of nitrogen (N) and phosphorus (P), the two main potential growth-limiting nutrients, influence macroalgal growth in temperate and tropical coastal waters ranging from low- ...

  19. Response of invertebrates from the hyporheic zone of chalk rivers to eutrophication and land use.

    Science.gov (United States)

    Pacioglu, Octavian; Moldovan, Oana Teodora

    2016-03-01

    Whereas the response of lotic benthic macroinvertebrates to different environmental stressors is a widespread practice nowadays in assessing the water and habitat quality, the use of hyporheic zone invertebrates is still in its infancy. In this study, classification and regression trees analysis were employed in order to assess the ecological requirements and the potential as bioindicators for the hyporheic zone invertebrates inhabiting four lowland chalk rivers (south England) with contrasting eutrophication levels (based on surface nitrate concentrations) and magnitude of land use (based on percentage of fine sediments load and median interstitial space). Samples of fauna, water and sediment were sampled twice, during low (summer) and high (winter) groundwater level, at depths of 20 and 35 cm. Certain groups of invertebrates (Glossosomatidae and Psychomyiidae caddisflies, and riffle beetles) proved to be good indicators of rural catchments, moderately eutrophic and with high fine sediment load. A diverse community dominated by microcrustaceans (copepods and ostracods) were found as good indicators of highly eutrophic urban streams, with moderate-high fine sediment load. However, the use of other taxonomic groups (e.g. chironomids, oligochaetes, nematodes, water mites and the amphipod Gammarus pulex), very widespread in the hyporheic zone of all sampled rivers, is of limited use because of their high tolerance to the analysed stressors. We recommend the use of certain taxonomic groups (comprising both meiofauna and macroinvertebrates) dwelling in the chalk hyporheic zone as indicators of eutrophication and colmation and, along with routine benthic sampling protocols, for a more comprehensive water and habitat quality assessment of chalk rivers.

  20. Eutrophic lichens respond to multiple forms of N: implications for critical levels and critical loads research

    Science.gov (United States)

    Sarah Jovan; Jennifer Riddell; Pamela E Padgett; Thomas Nash

    2012-01-01

    Epiphytic lichen communities are highly sensitive to excess nitrogen (N), which causes the replacement of native floras by N-tolerant, ‘‘weedy’’ eutrophic species. This shift is commonly used as the indicator of ecosystem ‘‘harm’’ in studies developing empirical critical levels (CLE) for ammonia (NH3) and critical loads (CLO) for N. To be most...

  1. Further east: eutrophication as a major threat to the flora of Vladimir Oblast, Russia.

    Science.gov (United States)

    Seregin, Alexey P

    2014-11-01

    Eutrophication remains a major threat to the flora of Western Europe despite measures to reduce nitrogen emissions. Although nutrient enrichment has been recorded for both inland waters and adjacent seas, there is almost no evidence from Russia for large-scale anthropogenic eutrophication of soils and its impact on terrestrial biota. I used the distribution grid data (337 grid squares, ca. 96 km(2)) on 1,384 vascular plants of Vladimir Oblast for two periods (1869-1999 vs. 2000-2012) to estimate the shifts in mean Ellenberg's indicator values for nitrogen and soil reaction. Decadal changes in the flora of acid sandy Meshchera Lowlands were observed directly during two grid surveys of 2002 and 2012 based on a coarser grid (50 squares, ca. 24 km(2)). Despite the spatial correlation of Ellenberg's indicator values for soil reaction and nitrogen, mean grid values for nitrogen are growing in areas with both acid and neutral soils. The changes in mean grid indicator values for nitrogen are caused by either local extinctions of species from nutrient-poor habitats or spread of nitrophilous plants. I found that oligotrophic habitats are declining rapidly within the eutrophic loamy landscapes. In contrast, changes in landscapes with acid sandy soils are caused by increasing number of records of nitrophilous species, both invasive and native. These two processes have different spatial patterns caused by varying levels of geochemical buffer capacity and should be considered separately. Fragmentary historical data on Vladimir Oblast flora agrees with the overall European picture of eutrophication in the twentieth century.

  2. Automatic classification of eutrophication of inland lakes from spacecraft data. [Oakland County, Michigan

    Science.gov (United States)

    Rogers, R. H. (Principal Investigator); Reed, L. E.; Shah, N. J.; Smith, V. E.

    1974-01-01

    The author has identified the following significant results. Spacecraft data and computer techniques can be used to rapidly map and store onto digital tapes watershed land use information. Software is now available by which this land use information can be rapidly and economically extracted from the tapes and related to coliform counts and other lake contaminants (e.g. phosphorus). These tools are basic elements for determining those land use factors and sources of nutrients that accelerate eutrophication in lakes and reservoirs.

  3. Eutrophic lakes as CO2 sinks - A survey of 19 lakes in India

    Science.gov (United States)

    Singh, G.

    2015-12-01

    Inland waters emit a substantial amount of CO2 every year, most recent syntheses estimate (Raymond et al. 2013, IPCC 2013). However, eutrophic water bodies, which constitute the majority of inland waters, are underrepresented in these syntheses and may absorb rather than emit CO2 because of their high productivity (Balmer and Downing 2011, Pacheco et al. 2013). We did a survey of 19 urban and peri-urban lakes in India across a wide range of climates and with varying levels of eutrophication to get a snapshot of lake air-water CO2 exchange. A majority of the lakes (12 out of 19) were undersaturated with CO2 during daytime. Surface water pCO2 varied from 26 to 4600 ppm. Using estimates of gas transfer velocity from two different methods, we found the average daytime flux of CO2 in these lakes to vary from -3.11 mg C m-2d-1 to 36 mg C m-2 d-1. Weighted-averages of pCO2 and flux using lake area were 692 ppm and 2.33 mg C m-2 d-1, respectively. However, these values were dominated by one large coastal lake that was saturated with CO2. The other 18 lakes yielded averages pCO2 and flux of 282 ppm and -0.65 mg C m-2 d-1. Eutrophication is one the biggest contemporary threats to the global freshwater supply, and is particularly severe in developing countries. This study, despite its limited scope, provides strong support to the fact that eutrophic lakes may act as CO2 sinks rather than sources. Follow-up studies on the diurnal and seasonal pCO2 trends and the metabolic characteristics of these lakes will reveal the determinants of their carbon metabolism.

  4. The effects of groundwater discharge, mowing, and eutrophication on fen vegetation evaluated over half a century

    OpenAIRE

    Belle, J.; Barendregt, Arie; P. P. Schot; M. J. Wassen

    2006-01-01

    Questions: Were continued groundwater discharge and mowing regimes sufficient for vegetation preservation from 1944 to 1993? Which has a stronger effect on vegetation development; groundwater discharge or mowing? What is the role of surface water eutrophication as driver of vegetation change? Location: Het Hol, The Netherlands (ca. 92 ha, 52°13' N, 5°05' E). Methods: Hydrology was simulated for the late 1940s, early 1960s and 1987. Vegetation maps (1944, 1960, 1975 and 1993) were compared for...

  5. Eutrophication and overfishing in temperate nearshore pelagic food webs: a network perspective

    OpenAIRE

    Vasas, V.; C. Lancelot; Rousseau, V.; Jordán, F.

    2007-01-01

    We investigated the effects of human activities on the pelagic food web structure of nearshore marine ecosystems. Their generic structure was established on the basis of literature review and analyzed by qualitative structural network analysis. Two main issues were addressed: (1) the role of species capable of forming harmful algal blooms (HABs) and red tides (Noctiluca spp.), as well as the role of jellyfish, in eutrophicated systems; (2) the contribution of human influences on food webs, fo...

  6. River eutrophication: irrigated vs. non-irrigated agriculture through different spatial scales.

    Science.gov (United States)

    Monteagudo, Laura; Moreno, José Luis; Picazo, Félix

    2012-05-15

    The main objective of this study was to determine how spatial scale may affect the results when relating land use to nutrient enrichment of rivers and, secondly, to investigate which agricultural practices are more responsible for river eutrophication in the study area. Agriculture was split into three subclasses (irrigated, non-irrigated and low-impact agriculture) which were correlated to stream nutrient concentration on four spatial scales: large scale (drainage area of total subcatchment and 100 m wide subcatchment corridors) and local scale (5 and 1 km radius buffers). Nitrate, ammonium and orthophosphate concentrations and land use composition (agriculture, urban and forest) were measured at 130 river reaches in south-central Spain during the 2001-2009 period. Results suggested that different spatial scales may lead to different conclusions. Spatial autocorrelation and the inadequate representation of some land uses produced unreal results on large scales. Conversely, local scales did not show data autocorrelation and agriculture subclasses were well represented. The local scale of 1 km buffer was the most appropriate to detect river eutrophication in central Spanish rivers, with irrigated cropland as the main cause of river pollution by nitrate. As regards river management, a threshold of 50% irrigated cropland within a 1 km radius buffer has been obtained using breakpoint regression analysis. This means that no more than 50% of irrigation croplands should be allowed near river banks in order to avoid river eutrophication. Finally, a methodological approach is proposed to choose the appropriate spatial scale when studying river eutrophication caused by diffuse pollution like agriculture. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. A review on the Control of Eutrophication in Deep and Shallow Lakes

    OpenAIRE

    BEKLİOĞLU, Meryem

    2014-01-01

    There has been a much debate about the relative importance of the determination of phytoplankton crops by nutrients (bottom-up control) or by zooplankton grazing (top-down control). Wide acceptance of the importance of nutrient concentrations in water quality deterioration has brought about external nutrient control by which eutrophication is, to some extent, reversible, and which has been proved its effectiveness mostly in deep lakes. In shallow lakes its effectiveness has not been as pronou...

  8. Long-term trends in eutrophication and nutrients in the coastal zone

    DEFF Research Database (Denmark)

    Clarke, Anne-Marie; Weckström, Kaarina; Conley, Daniel

    2006-01-01

    We used high-resolution paleoecological records of environmental change to study the rate and magnitude of eutrophication over the last century in two contrasting coastal ecosystems. A multiproxy approach using geochemical and biological indicators and diatom-based transfer functions provides...... in nutrient loading that have occurred in northwestern Europe, where the dissolved inorganic nitrogen (DIN) load has increased more than threefold in certain areas....

  9. Association and linkage analyses of RGS4 polymorphisms in schizophrenia.

    Science.gov (United States)

    Chowdari, Kodavali V; Mirnics, Karoly; Semwal, Prachi; Wood, Joel; Lawrence, Elizabeth; Bhatia, Triptish; Deshpande, Smita N; B K, Thelma; Ferrell, Robert E; Middleton, Frank A; Devlin, Bernie; Levitt, Pat; Lewis, David A; Nimgaonkar, Vishwajit L

    2002-06-01

    Gene expression analyses of postmortem cerebral cortex suggest that transcription of the regulator of G-protein signaling 4 (RGS4) is decreased in a diagnosis-specific manner in subjects with schizophrenia. To evaluate the possible role of RGS4 in the pathogenesis of schizophrenia, we conducted genetic association and linkage studies using samples ascertained independently in Pittsburgh and New Delhi and by the NIMH Collaborative Genetics Initiative. Using the transmission disequilibrium test, significant transmission distortion was observed in the Pittsburgh and NIMH samples. Among single-nucleotide polymorphisms (SNPs) spanning approximately 300 kb, significant associations involved four SNPs localized to a 10 kb region at RGS4, but the associated haplotypes differed. A trend for transmission distortion was also present in the Indian sample for haplotypes incorporating the same SNPs. Consistent with the linkage/association observed from the family-based tests, samples with affected siblings (NIMH, India) showed higher levels of allele sharing, identical by descent, at RGS4. When the US patients were contrasted to two population-based control samples, however, no significant differences were observed. To check the specificity of the transmission bias, we therefore examined US families with bipolar I disorder (BD1) probands. This sample also showed a trend for transmission distortion, and differed significantly from the population-based controls for the four-SNP haplotypes tested in the other samples. The transmission distortion is unlikely to be due to chance, but its mechanism and specificity require further study. Our results illustrate the potential power of combining gene expression profiling and genomic analyses to identify susceptibility genes for genetically complex disorders.

  10. Rethinking health sector procurement as developmental linkages in East Africa.

    Science.gov (United States)

    Mackintosh, Maureen; Tibandebage, Paula; Karimi Njeru, Mercy; Kariuki Kungu, Joan; Israel, Caroline; Mujinja, Phares G M

    2018-01-31

    Health care forms a large economic sector in all countries, and procurement of medicines and other essential commodities necessarily creates economic linkages between a country's health sector and local and international industrial development. These procurement processes may be positive or negative in their effects on populations' access to appropriate treatment and on local industrial development, yet procurement in low and middle income countries (LMICs) remains under-studied: generally analysed, when addressed at all, as a public sector technical and organisational challenge rather than a social and economic element of health system governance shaping its links to the wider economy. This article uses fieldwork in Tanzania and Kenya in 2012-15 to analyse procurement of essential medicines and supplies as a governance process for the health system and its industrial links, drawing on aspects of global value chain theory. We describe procurement work processes as experienced by front line staff in public, faith-based and private sectors, linking these experiences to wholesale funding sources and purchasing practices, and examining their implications for medicines access and for local industrial development within these East African countries. We show that in a context of poor access to reliable medicines, extensive reliance on private medicines purchase, and increasing globalisation of procurement systems, domestic linkages between health and industrial sectors have been weakened, especially in Tanzania. We argue in consequence for a more developmental perspective on health sector procurement design, including closer policy attention to strengthening vertical and horizontal relational working within local health-industry value chains, in the interests of both wider access to treatment and improved industrial development in Africa. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

  11. Particle swarm optimization with recombination and dynamic linkage discovery.

    Science.gov (United States)

    Chen, Ying-Ping; Peng, Wen-Chih; Jian, Ming-Chung

    2007-12-01

    In this paper, we try to improve the performance of the particle swarm optimizer by incorporating the linkage concept, which is an essential mechanism in genetic algorithms, and design a new linkage identification technique called dynamic linkage discovery to address the linkage problem in real-parameter optimization problems. Dynamic linkage discovery is a costless and effective linkage recognition technique that adapts the linkage configuration by employing only the selection operator without extra judging criteria irrelevant to the objective function. Moreover, a recombination operator that utilizes the discovered linkage configuration to promote the cooperation of particle swarm optimizer and dynamic linkage discovery is accordingly developed. By integrating the particle swarm optimizer, dynamic linkage discovery, and recombination operator, we propose a new hybridization of optimization methodologies called particle swarm optimization with recombination and dynamic linkage discovery (PSO-RDL). In order to study the capability of PSO-RDL, numerical experiments were conducted on a set of benchmark functions as well as on an important real-world application. The benchmark functions used in this paper were proposed in the 2005 Institute of Electrical and Electronics Engineers Congress on Evolutionary Computation. The experimental results on the benchmark functions indicate that PSO-RDL can provide a level of performance comparable to that given by other advanced optimization techniques. In addition to the benchmark, PSO-RDL was also used to solve the economic dispatch (ED) problem for power systems, which is a real-world problem and highly constrained. The results indicate that PSO-RDL can successfully solve the ED problem for the three-unit power system and obtain the currently known best solution for the 40-unit system.

  12. Seasonal changes in infrapopulations of Diplozoon kashmirensis Kaw, 1950 (Monogenea: Diplozoidae) along a eutrophic gradient.

    Science.gov (United States)

    Shah, Humaira Bashir; Yousuf, A R; Chishti, M Z; Ahmad, Fayaz

    2013-09-01

    Seasonal population dynamics of the monogenean, Diplozoon kashmirensis Kaw, on the gills of two cyprinid fish species, Schizothorax niger Heckel and Carassius carassius (Linnaeus), was investigated in three limnologically distinct trophic habitats located along the flood plain of River Jhelum in Kashmir from June 2006 to May 2008. The parasite infrapopulations exhibited a marked seasonal regime in infestation pattern as the infection indices increased to a much higher plateau during summer season at all the lakes, while the lows were recorded in winter. The heterogeneity in infection pattern indicates that water temperature is an important determinant of the seasonality of infrapopulations at all the localities. Furthermore, the results of our work clearly indicate that the parasite infrapopulations increased proportionally with eutrophication level and, as such, the highly eutrophic habitat, Anchar Lake, was significantly more favourable for parasite infrapopulations than the less eutrophic ones. However, the lakes presented no significant interlake differences in water temperature. Therefore, we could argue that interlake differences in the infestation pattern of parasite can be safely attributed to respective water quality in the lakes rather than water temperature. We propose that infrapopulations of the diplozoid studied herein do respond to differences in water quality of lakes and, thus, could qualify as simple and reliable indicator species in short-term comparative assays by lake managers.

  13. Community stoichiometry in a changing world: combined effects of warming and eutrophication on phytoplankton dynamics.

    Science.gov (United States)

    Domis, Lisette N De Senerpont; Van de Waal, Dedmer B; Helmsing, Nico R; Van Donk, Ellen; Mooij, Wolf M

    2014-06-01

    The current changes in our climate will likely have far-reaching consequences for aquatic ecosystems. These changes in the climate, however, do not act alone, and are often accompanied by additional stressors such as eutrophication. Both global warming and eutrophication have been shown to affect the timing and magnitude of phytoplankton blooms. Little is known about the combined effects of rising temperatures and eutrophication on the stoichiometry of entire phytoplankton communities. We exposed a natural phytoplankton spring community to different warming and phosphorus-loading scenarios using a full-factorial design. Our results demonstrate that rising temperatures promote the growth rate of an entire phytoplankton community. Furthermore, both rising temperatures and phosphorus loading stimulated the maximum biomass built up by the phytoplankton community. Rising temperatures led to higher carbon: nutrient stoichiometry of the phytoplankton community under phosphorus-limited conditions. Such a shift towards higher carbon: nutrient ratios, in combination with a higher biomass buildup, suggests a temperature-driven increase in nutrient use efficiency, the phytoplankton community. Importantly, with higher carbon: nutrient stoichiometry, phytoplankton is generally of poorer nutritional value for zooplankton. Thus, although warming may result in higher phytoplankton biomass, this may be accompanied by a stoichiometric mismatch between phytoplankton and their grazers, with possible consequences for the entire aquatic food web.

  14. Contrasting Eutrophication Risks and Countermeasures in Different Water Bodies: Assessments to Support Targeted Watershed Management.

    Science.gov (United States)

    Li, Tong; Chu, Chunli; Zhang, Yinan; Ju, Meiting; Wang, Yuqiu

    2017-06-29

    Eutrophication is a major problem in China. To combat this issue, the country needs to establish water quality targets, monitoring systems, and intelligent watershed management. This study explores a new watershed management method. Water quality is first assessed using a single factor index method. Then, changes in total nitrogen/total phosphorus (TN/TP) are analyzed to determine the limiting factor. Next, the study compares the eutrophication status of two water function districts, using a comprehensive nutritional state index method and geographic information system (GIS) visualization. Finally, nutrient sources are qualitatively analyzed. Two functional water areas in Tianjin, China were selected and analyzed: Qilihai National Wetland Nature Reserve and Yuqiao Reservoir. The reservoir is a drinking water source. Results indicate that total nitrogen (TN) and total phosphorus (TP) pollution are the main factors driving eutrophication in the Qilihai Wetland and Yuqiao Reservoir. Phosphorus was the limiting factor in the Yuqiao Reservoir; nitrogen was the limiting factor in the Qilihai Wetland. Pollution in Qilihai Wetland is more serious than in Yuqiao Reservoir. The study found that external sources are the main source of pollution. These two functional water areas are vital for Tianjin; as such, the study proposes targeted management measures.

  15. Phytoplankton Diversity Effects on Community Biomass and Stability along Nutrient Gradients in a Eutrophic Lake

    Directory of Open Access Journals (Sweden)

    Wang Tian

    2017-01-01

    Full Text Available The relationship between biodiversity and ecosystem functioning is a central issue in ecology, but how this relationship is affected by nutrient stress is still unknown. In this study, we analyzed the phytoplankton diversity effects on community biomass and stability along nutrient gradients in an artificial eutrophic lake. Four nutrient gradients, varying from slightly eutrophic to highly eutrophic states, were designed by adjusting the amount of polluted water that flowed into the lake. Mean phytoplankton biomass, species richness, and Shannon diversity index all showed significant differences among the four nutrient gradients. Phytoplankton community biomass was correlated with diversity (both species richness and Shannon diversity index, varying from positive to negative along the nutrient gradients. The influence of phytoplankton species richness on resource use efficiency (RUE also changed from positive to negative along the nutrient gradients. However, the influence of phytoplankton Shannon diversity on RUE was not significant. Both phytoplankton species richness and Shannon diversity had a negative influence on community turnover (measured as community dissimilarity, i.e., a positive diversity–stability relationship. Furthermore, phytoplankton spatial stability decreased along the nutrient gradients in the lake. With increasing nutrient concentrations, the variability (standard deviation of phytoplankton community biomass increased more rapidly than the average total biomass. Results in this study will be helpful in understanding the phytoplankton diversity effects on ecosystem functioning and how these effects are influenced by nutrient conditions in aquatic ecosystems.

  16. [Nutrient spatiotemporal distribution and eutrophication process in subsidence waters of Huainan and Huaibei mining areas, China].

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    Qu, Xi-Jie; Yi, Qi-Tao; Hu, You-Biao; Yan, Jia-Ping; Yu, Huai-Jun; Dong, Xiang-Lin

    2013-11-01

    A total of eight mining subsidence waters, including five sites in Huainan "Panxie" Mining Areas (PXS-1, PXS-2, PXS-3, PXS-4, and PXS-5) and three sites in Huaibei "Zhu-Yang huang" Mining Areas (HBDH, HBZH, HBNH), were selected to study the nutrient temporal and spatial distribution and trophic states. Among the sites, three sites (PXS-1, PXS-3, and HBDH) showed higher nutrient level and could be classified into moderate eutrophication, whereas the other five were in moderate nutrient level and mild eutrophication. Overall, the nutrient level of Huainan mining subsidence waters was higher than that of Huaibei mining subsidence waters. All the test samples in the two mining areas had a higher ratio of nitrogen to phosphorus (N:P), being 25-117 in Huainan and 17-157 in Huaibei, and with a seasonal variety, the lowest in growth season. The dissolved inorganic phosphorus (DIP) in total phosphorous (TP) occupied a small percentage, being averagely 15.4% and 18.4% in Huainan and Huaibei mining areas, respectively. Nitrate was the main specie of dissolved inorganic nitrogen (DIN), with the ratio of nitrate to DIN being 74% and 89% in Huainan and Huaibei mining areas, respectively. Relative to the waters age, human activities could be one of the main factors responsible for the high nutrient level and the faster eutrophication process of these waters.

  17. Eutrophication threatens Caribbean seagrasses - An example from Curaçao and Bonaire.

    Science.gov (United States)

    Govers, Laura L; Lamers, Leon P M; Bouma, Tjeerd J; de Brouwer, Jan H F; van Katwijk, Marieke M

    2014-12-15

    Seagrass beds are globally declining due to human activities in coastal areas. We here aimed to identify threats from eutrophication to the valuable seagrass beds of Curaçao and Bonaire in the Caribbean, which function as nursery habitats for commercial fish species. We documented surface- and porewater nutrient concentrations, and seagrass nutrient concentrations in 6 bays varying in nutrient loads. Water measurements only provided a momentary snapshot, due to timing, tidal stage, etc., but Thalassia testudinum nutrient concentrations indicated long-term nutrient loads. Nutrient levels in most bays did not raise any concern, but high leaf % P values of Thalassia in Piscadera Bay (∼0.31%) and Spanish Water Bay (∼0.21%) showed that seagrasses may be threatened by eutrophication, due to emergency overflow of waste water and coastal housing. We thus showed that seagrasses may be threatened and measures should be taken to prevent loss of these important nursery areas due to eutrophication. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Human-induced eutrophication maintains high parasite prevalence in breeding threespine stickleback populations.

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    Budria, Alexandre; Candolin, Ulrika

    2015-04-01

    Anthropogenic activities are having profound impacts on species interactions, with further consequences for populations and communities. We investigated the influence that anthropogenic eutrophication has on the prevalence of the parasitic tapeworm Schistocephalus solidus in threespine stickleback Gasterosteus aculeatus populations. We caught stickleback from four areas along the coast of Finland, and within each area from one undisturbed and one eutrophied habitat. We found the prevalence of the parasite to be lower in the eutrophied habitats at the start of the breeding season, probably because of fewer piscivorous birds that transmit the parasite. However, while the prevalence of the parasite declined across the season in the undisturbed habitat, it did less so in eutrophied habitats. We discuss different processes that could be behind the differences, such as lower predation rate on infected fish, higher food availability and less dispersal in eutrophied habitats. We found no effect of eutrophication on the proportion of infected stickleback that entered reproductive condition. Together with earlier findings, this suggests that eutrophication increases the proportion of infected stickleback that reproduce. This could promote the evolution of less parasite resistant populations, with potential consequences for the viability of the interacting parties of the host-parasite system.

  19. Asynchronous onset of eutrophication among shallow prairie lakes of the Northern Great Plains, Alberta, Canada.

    Science.gov (United States)

    Maheaux, Heather; Leavitt, Peter R; Jackson, Leland J

    2016-01-01

    Coherent timing of agricultural expansion, fertilizer application, atmospheric nutrient deposition, and accelerated global warming is expected to promote synchronous fertilization of regional surface waters and coherent development of algal blooms and lake eutrophication. While broad-scale cyanobacterial expansion is evident in global meta-analyses, little is known of whether lakes in discrete catchments within a common lake district also exhibit coherent water quality degradation through anthropogenic forcing. Consequently, the primary goal of this study was to determine whether agricultural development since ca. 1900, accelerated use of fertilizer since 1960, atmospheric deposition of reactive N, or regional climate warming has resulted in coherent patterns of eutrophication of surface waters in southern Alberta, Canada. Unexpectedly, analysis of sedimentary pigments as an index of changes in total algal abundance since ca. 1850 revealed that while total algal abundance (as β-carotene, pheophytin a) increased in nine of 10 lakes over 150 years, the onset of eutrophication varied by a century and was asynchronous across basins. Similarly, analysis of temporal sequences with least-squares regression revealed that the relative abundance of cyanobacteria (echinenone) either decreased or did not change significantly in eight of the lakes since ca. 1850, whereas purple sulfur bacteria (as okenone) increased significantly in seven study sites. These patterns are consistent with the catchment filter hypothesis, which posits that lakes exhibit unique responses to common forcing associated with the influx of mass as water, nutrients, or particles. © 2015 John Wiley & Sons Ltd.

  20. Reproductive strategies and isolation-by-demography in a marine clonal plant along an eutrophication gradient.

    Science.gov (United States)

    Oliva, Silvia; Romero, Javier; Pérez, Marta; Manent, Pablo; Mascaró, Oriol; Serrão, Ester A; Coelho, Nelson; Alberto, Filipe

    2014-12-01

    Genetic diversity in clonal organisms includes two distinct components, (i) the diversity of genotypes or clones (i.e. genotypic richness) in a population and (ii) that of the alleles (i.e. allelic and gene diversity within populations, and differentiation between populations). We investigated how population differentiation and genotypic components are associated across a gradient of eutrophication in a clonal marine plant. To that end, we combined direct measurements of sexual allocation (i.e. flower and seed counts) and genotypic analyses, which are used as an estimator of effective sexual reproduction across multiple generations. Genetic differentiation across sites was also modelled according to a hypothesis here defined as isolation-by-demography, in which we use population-specific factors, genotypic richness and eutrophication that are hypothesized to affect the source-sink dynamics and thus influence the genetic differentiation between a pair of populations. Eutrophic populations exhibited lower genotypic richness, in agreement with lower direct measurements of sexual allocation and contemporaneous gene flow. Genetic differentiation, while not explained by distance, was best predicted by genotypic richness and habitat quality. A multiple regression model using these two predictors was considered the best model (R(2) = 0.43). In this study, the relationship between environment and effective sexual-asexual balance is not simply (linearly) predicted by direct measurements of sexual allocation. Our results indicate that population-specific factors and the isolation-by-demography model should be used more often to understand genetic differentiation. © 2014 John Wiley & Sons Ltd.

  1. Integration of Bayesian analysis for eutrophication prediction and assessment in a landscape lake.

    Science.gov (United States)

    Yang, Likun; Zhao, Xinhua; Peng, Sen; Zhou, Guangyu

    2015-01-01

    Eutrophication models have been widely used to assess water quality in landscape lakes. Because flow rate in landscape lakes is relatively low and similar to that of natural lakes, eutrophication is more dominant in landscape lakes. To assess the risk of eutrophication in landscape lakes, a set of dynamic equations was developed to simulate lake water quality for total nitrogen (TN), total phosphorous (TP), dissolve oxygen (DO) and chlorophyll a (Chl a). Firstly, the Bayesian calibration results were described. Moreover, the ability of the model to reproduce adequately the observed mean patterns and major cause-effect relationships for water quality conditions in landscape lakes were presented. Two loading scenarios were used. A Monte Carlo algorithm was applied to calculate the predicated water quality distributions, which were used in the established hierarchical assessment system for lake water quality risk. The important factors affecting the lake water quality risk were defined using linear regression analysis. The results indicated that the variations in the landscape lake receiving recharge water quality caused considerable landscape lake water quality risk in the surrounding area. Moreover, the Chl a concentration in lake water was significantly affected by TP and TN concentrations; the lake TP concentration was the limiting factor for growth of plankton in lake water. The lake water TN concentration provided the basic nutritional requirements. Lastly, lower TN and TP concentrations in the receiving recharge water caused increased lake water quality risk.

  2. Urban eutrophication and its spurring conditions in the Murchison Bay of Lake Victoria.

    Science.gov (United States)

    Kabenge, Martin; Wang, Hongtao; Li, Fengting

    2016-01-01

    The efficiency of Lake Victoria in providing its ecosystem services to riparian states, both immediate and along the Nile river basin, is strongly related to its water quality. Over the past few decades, eutrophication has increased in the lake arising from increased inflow of nutrients. This study was carried out in the Murchison Bay area of Lake Victoria with the aims of assessing the progress of eutrophication nutrient enrichment into the lake between 1990 and 2014. Using Landsat satellite floating algae index (FAI) products and data from laboratory analysis of water samples, the study revealed that floating algae reoccurred periodically with coverage varying between 1 and 18 km(2). The findings also indicated that the range of nitrate-nitrogen concentrations increased greatly with maximum concentrations recorded at 31.2 mg l(-1) in 2007 from 0.084 mg l(-1) in 1990. The soluble reactive phosphorus concentration range showed a maximum of 1.45 mg l(-1) in 2007 from 0.043 mg l(-1) in 1990. The chlorophyll levels increased from an average of 17 μg l(-1) in 1992 by threefold in 1996 but had however declined and halved in intensity by 2011. The eutrophication that has occurred in Lake Victoria over the past decades has been due to pollution from industrial, residential, and agricultural areas within the catchment.

  3. Effects of eutrophication on diatom abundance, biovolume and diversity in tropical coastal waters.

    Science.gov (United States)

    Lim, Joon Hai; Lee, Choon Weng

    2017-08-03

    Diatom abundance, biovolume and diversity were measured over a 2-year period along the Straits of Malacca at two stations with upper (Klang) and lower (Port Dickson) states of eutrophication. Diatom abundance, which ranged from 0.2 × 10 4 to 21.7 × 10 4  cells L -1 at Klang and 0.9 × 10 3 - 41.3 × 10 3  cells L -1 at Port Dickson, was influenced partly by nutrient concentrations. At Klang, the diatoms were generally smaller and less diverse (H' = 0.77 ± 0.48) and predominated by Skeletonema spp. (60 ± 32% of total diatom biomass). In contrast, diatoms were larger and more diverse (H' = 1.40 ± 0.67) at Port Dickson. Chaetoceros spp. were the most abundant diatoms at Port Dickson but attributed only 48 ± 30% of total diatom biomass. Comparison of both Klang and Port Dickson showed that their diatom community structure differed and that eutrophication reduced diatom diversity at Klang. We also observed how Si(OH) 4 affected the abundance of Skeletonema spp. which in turn influenced the temporal variation of diatom community at Klang. Our results highlighted how eutrophication affects diatom diversity and community structure.

  4. Algal bloom sedimentation induces variable control of lake eutrophication by phosphorus inactivating agents.

    Science.gov (United States)

    Wang, Changhui; Bai, Leilei; Jiang, He-Long; Xu, Huacheng

    2016-07-01

    Lake eutrophication typically occurs with a syndrome of algae breeding and biomass accumulation (e.g., algal blooms). Therefore, the effect of algal bloom sedimentation on eutrophication control by phosphorus (P) inactivating agents was assessed herein. Three commercial products, including aluminum (Al) sulfate, iron (Fe) sulfate, and a lanthanum-modified clay (Phoslock®), as well as one easily available by-product, drinking water treatment residue (DWTR), were selected. The most important finding was that during algae sedimentation, P immobilization from the overlying water by Al, Phoslock®, and DWTR was dominated by a long-term slow phase (>150d), while Fe has limited effectiveness on the immobilization. Further analysis indicated that the algae sedimentation effect was mainly due to the slow release of P from algae, leading to relatively limited P available for the inactivating agents. Then, a more unfavorable effect on the P immobilization capability of inactivating agents was caused by the induced anaerobic conditions, the released organic matter from algae, and the increased sulfide in the overlying water and sediments during sedimentation. Overall, algae sedimentation induced variable control of eutrophication by P inactivating agents. Accordingly, recommendations for future works about algal lake restoration were also proposed. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Phytoplankton Diversity Effects on Community Biomass and Stability along Nutrient Gradients in a Eutrophic Lake.

    Science.gov (United States)

    Tian, Wang; Zhang, Huayong; Zhao, Lei; Zhang, Feifan; Huang, Hai

    2017-01-20

    The relationship between biodiversity and ecosystem functioning is a central issue in ecology, but how this relationship is affected by nutrient stress is still unknown. In this study, we analyzed the phytoplankton diversity effects on community biomass and stability along nutrient gradients in an artificial eutrophic lake. Four nutrient gradients, varying from slightly eutrophic to highly eutrophic states, were designed by adjusting the amount of polluted water that flowed into the lake. Mean phytoplankton biomass, species richness, and Shannon diversity index all showed significant differences among the four nutrient gradients. Phytoplankton community biomass was correlated with diversity (both species richness and Shannon diversity index), varying from positive to negative along the nutrient gradients. The influence of phytoplankton species richness on resource use efficiency (RUE) also changed from positive to negative along the nutrient gradients. However, the influence of phytoplankton Shannon diversity on RUE was not significant. Both phytoplankton species richness and Shannon diversity had a negative influence on community turnover (measured as community dissimilarity), i.e., a positive diversity-stability relationship. Furthermore, phytoplankton spatial stability decreased along the nutrient gradients in the lake. With increasing nutrient concentrations, the variability (standard deviation) of phytoplankton community biomass increased more rapidly than the average total biomass. Results in this study will be helpful in understanding the phytoplankton diversity effects on ecosystem functioning and how these effects are influenced by nutrient conditions in aquatic ecosystems.

  6. Identification of Cyanobacteria in a Eutrophic Coastal Lagoon on the Southern Baltic Coast

    Directory of Open Access Journals (Sweden)

    Martin Albrecht

    2017-05-01

    Full Text Available Cyanobacteria are found worldwide in various habitats. Members of the picocyanobacteria genera Synechococcus and Prochlorococcus dominate in oligotrophic ocean waters. Other picocyanobacteria dominate in eutrophic fresh or brackish waters. Usually, these are morphologically determined as species of the order Chroococcales/clade B2. The phytoplankton of a shallow, eutrophic brackish lagoon was investigated. Phytoplankton was dominated by Aphanothece-like morphospecies year-round for more than 20 years, along a trophy and salinity gradient. A biphasic approach using a culture-independent and a culture-dependent analysis was applied to identify the dominant species genetically. The 16S rRNA gene phylogeny of clone sequences and isolates indicated the dominance of Cyanobium species (order Synechococcales sensu Komárek/clade C1 sensu Shih. This difference between morphologically and genetically based species identifications has consequences for applying the Reynolds functional-groups system, and for validity long-term monitoring data. The literature shows the same pattern as our results: morphologically, Aphanothece-like species are abundant in eutrophic shallow lagoons, and genetically, Cyanobium is found in similar habitats. This discrepancy is found worldwide in the literature on fresh- and brackish-water habitats. Thus, most Aphanothece-like morphospecies may be, genetically, members of Cyanobium.

  7. Eutrophication of U.S. freshwaters: analysis of potential economic damages.

    Science.gov (United States)

    Dodds, Walter K; Bouska, Wes W; Eitzmann, Jeffrey L; Pilger, Tyler J; Pitts, Kristen L; Riley, Alyssa J; Schloesser, Joshua T; Thornbrugh, Darren J

    2009-01-01

    Human-induced eutrophication degrades freshwater systems worldwide by reducing water quality and altering ecosystem structure and function. We compared current total nitrogen (TN) and phosphorus (TP) concentrations for the U.S. Environmental Protection Agency nutrient ecoregions with estimated reference conditions. In all nutrient ecoregions, current median TN and TP values for rivers and lakes exceeded reference median values. In 12 of 14 ecoregions, over 90% of rivers currently exceed reference median values. We calculated potential annual value losses in recreational water usage, waterfront real estate, spending on recovery of threatened and endangered species, and drinking water. The combined costs were approximately $2.2 billion annually as a result of eutrophication in U.S. freshwaters. The greatest economic losses were attributed to lakefront property values ($0.3-2.8 billion per year, although this number was poorly constrained) and recreational use ($0.37-1.16 billion per year). Our evaluation likely underestimates economic losses incurred from freshwater eutrophication. We document potential costs to identify where restoring natural nutrient regimes can have the greatest economic benefits. Our research exposes gaps in current records (e.g., accounting for frequency of algal blooms and fish kills) and suggests further research is necessary to refine cost estimates.

  8. Modelling eutrophication and microbial risks in peri-urban river systems using discriminant function analysis.

    Science.gov (United States)

    Pinto, U; Maheshwari, B; Shrestha, S; Morris, C

    2012-12-01

    The methodology currently available to river managers for assessment of river conditions for eutrophication and microbial risks is often time consuming and costly. There is a need for efficient predictive tools based on easily measured variables for implementing appropriate management strategies and providing advice to local river users on river health and associated risks. Using the Hawkesbury-Nepean River system in New South Wales, Australia as case study, a stepwise discriminant function analysis was employed to develop two predictive models, one for river eutrophication risk and the other for microbial risk. The models are intended for a preliminary assessment of a river reach, particularly to assess the level of risk (high or low) for algal bloom and whether the river water is suitable for primary contact activities such as swimming. The input variables for both models included saturated dissolved oxygen and turbidity, while the eutrophication risk model included temperature as an additional variable. When validated with an independent data set, both models predicted the observed risk category accurately in two out of three instances. Since the models developed in this study use only two or three easy-to-measure variables, their application can help in rapid assessment of river conditions, result in potential cost saving in river monitoring programs and assist in providing timely advice to community and other users for a particular aspect of river use. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Floating rice-culture system for nutrient remediation and feed production in a eutrophic lake.

    Science.gov (United States)

    Srivastava, Ankita; Chun, Seong-Jun; Ko, So-Ra; Kim, Junhwan; Ahn, Chi-Yong; Oh, Hee-Mock

    2017-12-01

    The increased inputs of nutrients have been demonstrated to be a major contributing factor to the eutrophication of lakes and reservoirs which can lead to the production of harmful algal/cyanobacterial blooms and deleteriously affect the aesthetics of water-bodies. Floating plant-culture systems have been widely used for the ecological remediation of eutrophic water in a cost-effective manner. We investigated the applicability of Korean japonica rice variety 'Nampyeong' in a floating-culture system in a eutrophic lake for nutrient uptake and biomass production. Chemical and organic compound compositions were analyzed two times during the growth stages of the rice plant: 98 DAT (days after transplanting) and 165 DAT. Total nitrogen and phosphorus contributed around 1.36 and 0.15 (% dry weight), respectively, in rice plant components at 165 DAT. Crude protein, lipids, fiber and ash were 4.35, 1.91, 23.66 and 5.55 (% dry weight), respectively. In addition, microcystin levels in the rice plant components ranged from 0.0008 to 0.002 μg/g and did not exceed the recommended tolerable limits. These results suggested that the developed floating rice-culture system showed a good potential as a holistic management approach in terms of nutrient reduction, rice production for further use as feed and for bloom control. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Enhanced effects of biotic interactions on predicting multispecies spatial distribution of submerged macrophytes after eutrophication.

    Science.gov (United States)

    Song, Kun; Cui, Yichong; Zhang, Xijin; Pan, Yingji; Xu, Junli; Xu, Kaiqin; Da, Liangjun

    2017-10-01

    Water eutrophication creates unfavorable environmental conditions for submerged macrophytes. In these situations, biotic interactions may be particularly important for explaining and predicting the submerged macrophytes occurrence. Here, we evaluate the roles of biotic interactions in predicting spatial occurrence of submerged macrophytes in 1959 and 2009 for Dianshan Lake in eastern China, which became eutrophic since the 1980s. For the four common species occurred in 1959 and 2009, null species distribution models based on abiotic variables and full models based on both abiotic and biotic variables were developed using generalized linear model (GLM) and boosted regression trees (BRT) to determine whether the biotic variables improved the model performance. Hierarchical Bayesian-based joint species distribution models capable of detecting paired biotic interactions were established for each species in both periods to evaluate the changes in the biotic interactions. In most of the GLM and BRT models, the full models showed better performance than the null models in predicting the species presence/absence, and the relative importance of the biotic variables in the full models increased from less than 50% in 1959 to more than 50% in 2009 for each species. Moreover, co-occurrence correlation of each paired species interaction was higher in 2009 than that in 1959. The findings suggest biotic interactions that tend to be positive play more important roles in the spatial distribution of multispecies assemblages of macrophytes and should be included in prediction models to improve prediction accuracy when forecasting macrophytes' distribution under eutrophication stress.

  11. Do food processing industries contribute to the eutrophication of aquatic systems?

    Science.gov (United States)

    Tusseau-Vuillemin, M H

    2001-10-01

    Eutrophication is the enrichment of water bodies with plant nutrients and precursors, typically nitrogen, phosphorus, and organic matter. There exists a "natural" and slow eutrophication, which, over geological times, turns a lake into a marsh and then dries it entirely. Today, however, eutrophication is mostly referred to the human process that "results in the stimulation of an array of symptomatic changes, among which increased production of algae and macrophytes, deterioration of water quality and other symptomatic changes are found to be undesirable and interfere with water uses" as defined by the OECD in 1982. This undesirable process is observed mostly in enclosed water bodies, such as lakes, but also in some rivers, some estuaries, and some coastal zones. In most freshwater systems, phosphorus has been identified as the "limiting nutrient" to phytoplankton development. This nutrient is brought to aquatic environments from rock weathering, soil leaching, and rain (natural sources), but also and mostly from agricultural runoff and domestic sewage. Some food processing industries (meat, vegetables, cheese processing) also contribute significantly to the phosphorus budget, even though the pollution may be due to floor and utensil cleaning rather than to direct food wastes. Copyright 2001 International Life Sciences Institute.

  12. Eutrophication patterns in an eastern Mediterranean coastal lagoon: Vassova, Delta Nestos, Macedonia, Greece

    Directory of Open Access Journals (Sweden)

    S. ORFANIDIS

    2005-12-01

    Full Text Available The results of an intensive monitoring study of main eutrophication parameters in relation to fish farming management, climate and hydrography in the Vassova coastal lagoon (Nestos Delta are presented. The overall aim is to produce basic knowledge in order to contribute to the management of eutrophication of coastal lagoons at local and national levels. Due to extensive spatiotemporal variability of the measured parameters correlation and regression polynomial analysis was used to identify patterns (p<0.05. Freshwater was the main source of nitrate and phosphate in the lagoon. This finding has justified the reduction of freshwater inflow in the past, which, however, has increased mean salinity to 30 PSU and reduced spatial salinity gradients. Maximum nitrate values in winter coincided with adverse climatic and hydrographic conditions (high precipitation, strong NE to E winds and low tide and fish farming management that hinder water circulation. Dissolved phosphorus variability indicated the combination of the external (freshwaters and internal (sediment P-sources. N/P water values indicated nitrogen being the most important nutrient for primary producers throughout the year, except in winter, when phosphorus was the most important nutrient. Practical measures for improving fish farming practices to decrease “eutrophication risk” during winter are suggested. Existing nutrient data from the Vassova and from other Greek lagoons in comparison were also presented and discussed.

  13. Growth rate, protein:RNA ratio and stoichiometric homeostasis of submerged macrophytes under eutrophication stress

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    Xing W.

    2016-01-01

    Full Text Available Growth rate hypothesis (GRH and stoichiometric homeostasis of photoautotrophs have always been questioned. However, little is known about GRH and stoichiometric homeostasis of aquatic plants, especially submerged macrophytes. Therefore, we aim to test the GRH and explore stoichiometric homeostasis of four freshwater submerged macrophytes under eutrophication stress. At the single species level and the multi-species level, N:P ratios of Potamogeton maackianus, Myriophyllum spicatum, Vallisneria natans and Ceratophyllum demersum had no consistent trends with growth rates. However, protein:RNA ratios of P. maackianus, M. spicatum and V. natans all correlated negatively with growth rates, demonstrating GRH can apply to freshwater submerged macrophytes, even though they are threatening by eutrophication stress. Protein:RNA ratios positively correlated with N:P ratios in culture media and tissues in submerged macrophytes except in P. maackianus (30d, suggesting effects of varying N:P ratios in culture media on protein:RNA ratios are basically in concert with tissue N:P ratios under short-time eutrophication stress. Stoichiometric homeostasis coefficients (HN:P indicated submerged macrophytes have weak homeostasis. Stoichiometric homeostasis of V. natans was stronger than those of P. maackianus, M. spicatum and C. demersum. The differences in GRH and homeostasis of the four submerged macrophytes may be due to species traits.

  14. Consequences of eutrophication in the management of water resources in Mediterranean reservoirs: A case study of Lake Cedrino (Sardinia, Italy

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    Bachisio Mario Padedda

    2017-10-01

    Full Text Available One of the primary detrimental effects of eutrophication is the tendency of nuisance cyanobacterial species to increase in number and biomass in freshwater ecosystems. The aim of this study was to investigate possible management actions to control eutrophication and assure water use of a eutrophic deep Mediterranean climate reservoir, dominated by cyanobacteria. With this goal, we defined the trophic state of Lake Cedrino (Sardinia, Italy and studied its phytoplankton, paying particular attention to cyanobacteria, and to seasonal variation of phytoplankton in relation to seasonal variation of environmental variables. The water samples were collected monthly from September 2010 to August 2011 at differing depths from the surface of the water to the bottom at a station located in the deeper portion of the reservoir. Physical, chemical, nutrient, qualitative and quantitative analyses of phytoplankton were performed, and the trophic state was evaluated based on the Trophic State Index and the OECD model. Abundance of nutrients and phytoplankton (cell density, biomass and chlorophyll a indicated a eutrophic condition of the reservoir. In summer, phytoplankton species composition was dominated by nuisance cyanobacteria, particularly Aphanizomenon flosaquae, thereby requiring management plans for harmful blooms. On the base of lake features, we propose management actions at different scales and levels to resolve eutrophication and to allow water use: from nutrient load reduction in the watershed (primarily from point-sources to deep water aeration, to immediately face an attenuation of eutrophic effects. This study is the first explorative step in planning restoration of Lake Cedrino.

  15. The Potential Impacts of Climate Change Factors on Freshwater Eutrophication: Implications for Research and Countermeasures of Water Management in China

    Directory of Open Access Journals (Sweden)

    Rui Xia

    2016-03-01

    Full Text Available Water eutrophication has become one of the most serious aquatic environmental problems around the world. More and more research has indicated climate change as a major natural factor that will lead to the acceleration of eutrophication in rivers and lakes. However, understanding the mechanism of climate change’s effect on water eutrophication is difficult due to the uncertainties caused by its complex, non-linear process. There is considerable uncertainty about the magnitude of future temperature changes, and how these will drive eutrophication in water bodies at regional scales under the effect of human activities. This review collects the existing international and domestic literature from the last 10 years, discussing the most sensitive factors of climate change (i.e., temperature, precipitation, wind, and solar radiation and analyzing their interaction with water eutrophication. Case studies of serious eutrophication and algal bloom problems in China are discussed to further demonstrate the conclusion. Finally, adaptation countermeasures and related implications are proposed in order to foster the development of sustainability strategies for water management in China.

  16. Effect of coastal eutrophication on heavy metal bioaccumulation and oral bioavailability in the razor clam, Sinonovacula constricta.

    Science.gov (United States)

    Tu, Tengxiu; Li, Shunxing; Chen, Lihui; Zheng, Fengying; Huang, Xu-Guang

    2014-10-01

    As traditional seafoods, the razor clams are widely distributed from tropical to temperate areas. Coastal razor clams are often exposed to eutrophication. Heavy metal contamination is critical for seafood safety. However, how eutrophication affects bioaccumulation and oral bioavailability of heavy metals in the razor clams is unknown. After a four-month field experimental cultivation, heavy metals (Fe, Cu, Ni, V, As, and Pb) could be bioaccumulated by the razor clams (Sinonovacula constricta) through exposure to metals present in water and sediments or in the food chain, and then transferred to human via consumption of razor clams. Bionic gastrointestinal digestion and monolayer liposome extraction are used for metal oral bioavailability (OBA) assessment. The influence of eutrophication on OBA is decreased for Fe and Pb and increased for V. A significant positive linear correlation was observed between the bioaccumulation factors of Fe, Ni, V, and As in razor clams and the coastal eutrophication. These results may be due to the effect of eutrophication on metal species transformation in coastal seawater and subcellular distribution in razor clams. The maximum allowable daily intakes of razor clams are controlled by eutrophication status and the concentration of affinity-liposome As in razor clams. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Are Birth Certificate and Hospital Discharge Linkages Performed in 52 Jurisdictions in the United States?

    Science.gov (United States)

    Kim, Shin Y; Ahuja, Sukhjeet; Stampfel, Caroline; Williamson, Dhelia

    2015-12-01

    The purpose of this study was to determine the number and characteristics of US State Registrars of Vital Statistics (Vital Registrars) and State Systems Development Initiative (SSDI) Coordinators that link birth certificate and hospital discharge data as well as using linkage processes. Vital Registrars and SSDI Coordinators in all 52 vital records jurisdictions (50 states, District of Columbia, and New York City) were asked to complete a 41-question survey. We examined frequency distributions among completed surveys using SAS 9.3. The response rate was 100% (N = 52) for Vital Registrars and 96% (N = 50) for SSDI Coordinators. Nearly half of Vital Registrars (n = 22) and SSDI Coordinators (n = 23) reported that their jurisdiction linked birth certificate and hospital discharge records at least once in the last 4 years. Among those who link, the majority of Vital Registrars (77.3%) and SSDI Coordinators (82.6) link both maternal and infant hospital discharge records to the birth certificate. Of those who do not link, 43% of the Vital Registrars and 55% of SSDI Coordinators reported an interest in linking birth certificate and hospital discharge data. Reasons for not linking included lack of staff time, inability to access raw data, high cost, and unavailability of personal identifiers to link the two sources. Results of our analysis provide a national perspective on data linkage practices in the US. Our findings can be used to promote further data linkages, facilitate sharing of data and linkage methodologies, and identify uses of the resulting linked data.

  18. Synthesis and properties of ApA analogues with shortened phosphonate internucleotide linkage.

    Science.gov (United States)

    Králíková, Sárka; Buděšínský, Miloš; Barvík, Ivan; Masojídková, Milena; Točík, Zdeněk; Rosenberg, Ivan

    2011-01-01

    A complete series of the 2 '-5 ' and 3 '-5 ' regioisomeric types of r(ApA) and 2 '-d(ApA) analogues with the α-hydroxy-phosphonate C3 '-O-P-CH(OH)-C4 ″ internucleotide linkage, isopolar but non-isosteric with the phosphodiester one, were synthesized and their hybridization properties with polyU studied. Due to the chirality on the 5 '-carbon atom of the modified internucleotide linkage bearing phosphorus and hydroxy moieties, each regioisomeric type of ApA dimer is split into epimeric pairs. To examine the role of the 5 '-hydroxyl of the α-hydroxy-phosphonate moiety during hybridization, the appropriate r(ApA) analogues with 3 '(2 ')-O-P-CH(2)-C4 ″ linkage lacking the 5 '-hydroxyl were synthesized. Nuclear magnetic resonance (NMR) spectroscopy study on the conformation of the modified sugar-phosphate backbone, along with the hybridization measurements, revealed remarkable differences in the stability of complexes with polyU, depending on the 5 '-carbon atom configuration. Potential usefulness of the α-hydroxy-phosphonate linkage in modified oligoribonucleotides is discussed.

  19. Fine mapping quantitative trait loci under selective phenotyping strategies based on linkage and linkage disequilibrium criteria

    DEFF Research Database (Denmark)

    Ansari-Mahyari, S; Berg, P; Lund, M S

    2009-01-01

    disequilibrium-based sampling criteria (LDC) for selecting individuals to phenotype are compared to random phenotyping in a quantitative trait loci (QTL) verification experiment using stochastic simulation. Several strategies based on LAC and LDC for selecting the most informative 30%, 40% or 50% of individuals......, in order to estimate unbiased QTL parameters based on LAC in a large half-sib family, prior information on QTL position was required. The LDC improved the accuracy to estimate the QTL position but not significantly compared to random phenotyping with the same sample size. When applying LDC (all phenotyping......In fine mapping of a large-scale experimental population where collection of phenotypes are very expensive, difficult to record or time-demanding, selective phenotyping could be used to phenotype the most informative individuals. Linkage analyses based sampling criteria (LAC) and linkage...

  20. Using object oriented bayesian networks to model linkage, linkage disequilibrium and mutations between STR markers.

    Directory of Open Access Journals (Sweden)

    Daniel Kling

    Full Text Available In a number of applications there is a need to determine the most likely pedigree for a group of persons based on genetic markers. Adequate models are needed to reach this goal. The markers used to perform the statistical calculations can be linked and there may also be linkage disequilibrium (LD in the population. The purpose of this paper is to present a graphical Bayesian Network framework to deal with such data. Potential LD is normally ignored and it is important to verify that the resulting calculations are not biased. Even if linkage does not influence results for regular paternity cases, it may have substantial impact on likelihood ratios involving other, more extended pedigrees. Models for LD influence likelihoods for all pedigrees to some degree and an initial estimate of the impact of ignoring LD and/or linkage is desirable, going beyond mere rules of thumb based on marker distance. Furthermore, we show how one can readily include a mutation model in the Bayesian Network; extending other programs or formulas to include such models may require considerable amounts of work and will in many case not be practical. As an example, we consider the two STR markers vWa and D12S391. We estimate probabilities for population haplotypes to account for LD using a method based on data from trios, while an estimate for the degree of linkage is taken from the literature. The results show that accounting for haplotype frequencies is unnecessary in most cases for this specific pair of markers. When doing calculations on regular paternity cases, the markers can be considered statistically independent. In more complex cases of disputed relatedness, for instance cases involving siblings or so-called deficient cases, or when small differences in the LR matter, independence should not be assumed. (The networks are freely available at http://arken.umb.no/~dakl/BayesianNetworks..

  1. Genome-wide linkage scan for colorectal cancer susceptibility genes supports linkage to chromosome 3q

    Directory of Open Access Journals (Sweden)

    Velculescu Victor E

    2008-04-01

    Full Text Available Abstract Background Colorectal cancer is one of the most common causes of cancer-related mortality. The disease is clinically and genetically heterogeneous though a strong hereditary component has been identified. However, only a small proportion of the inherited susceptibility can be ascribed to dominant syndromes, such as Hereditary Non-Polyposis Colorectal Cancer (HNPCC or Familial Adenomatous Polyposis (FAP. In an attempt to identify novel colorectal cancer predisposing genes, we have performed a genome-wide linkage analysis in 30 Swedish non-FAP/non-HNPCC families with a strong family history of colorectal cancer. Methods Statistical analysis was performed using multipoint parametric and nonparametric linkage. Results Parametric analysis under the assumption of locus homogeneity excluded any common susceptibility regions harbouring a predisposing gene for colorectal cancer. However, several loci on chromosomes 2q, 3q, 6q, and 7q with suggestive linkage were detected in the parametric analysis under the assumption of locus heterogeneity as well as in the nonparametric analysis. Among these loci, the locus on chromosome 3q21.1-q26.2 was the most consistent finding providing positive results in both parametric and nonparametric analyses Heterogeneity LOD score (HLOD = 1.90, alpha = 0.45, Non-Parametric LOD score (NPL = 2.1. Conclusion The strongest evidence of linkage was seen for the region on chromosome 3. Interestingly, the same region has recently been reported as the most significant finding in a genome-wide analysis performed with SNP arrays; thus our results independently support the finding on chromosome 3q.

  2. Identifying and Mapping Linkages between Actors in the Climate ...

    African Journals Online (AJOL)

    Promoting innovations in climate change requires innovation partnerships and linkages and also creating an enabling environment for actors. The paper reviewed available information on the identification and mapping of linkages between actors in the climate change innovation system. The findings showed different ...

  3. The first genetic linkage map of Eucommia ulmoides

    Indian Academy of Sciences (India)

    In accordance with pseudo-testcross strategy, the first genetic linkage map of Eucommia ulmoides Oliv. was constructed by an F1 population of 122 plants ... These genetic linkage maps facilitate the analysis of QTL that control commercially ..... to avoid inbreeding depression of long growth-cycle trees. The pseudo-testcross ...

  4. Localizing genes using linkage disequilibrium in plants: integrating ...

    African Journals Online (AJOL)

    Localizing genes using linkage disequilibrium in plants: integrating lessons from the medical genetics. ... Linkage disequilibrium (LD) or association mapping, is a candidate gene approach that relies on detecting a statistical association between the desired quantitative trait and a molecular marker allele. This approach is ...

  5. A microsatellite genetic linkage map of black rockfish ( Sebastes schlegeli)

    Science.gov (United States)

    Chu, Guannan; Jiang, Liming; He, Yan; Yu, Haiyang; Wang, Zhigang; Jiang, Haibin; Zhang, Quanqi

    2014-12-01

    Ovoviviparous black rockfish ( Sebastes schlegeli) is an important marine fish species for aquaculture and fisheries in China. Genetic information of this species is scarce because of the lack of microsatellite markers. In this study, a large number of microsatellite markers of black rockfish were isolated by constructing microsatellite-enriched libraries. Female- and male-specific genetic linkage maps were constructed using 435 microsatellite markers genotyped in a full-sib family of the fish species. The female linkage map contained 140 microsatellite markers, in which 23 linkage groups had a total genetic length of 1334.1 cM and average inter-marker space of 13.3 cM. The male linkage map contained 156 microsatellite markers, in which 25 linkage groups had a total genetic length of 1359.6 cM and average inter-marker distance of 12.4 cM. The genome coverage of the female and male linkage maps was 68.6% and 69.3%, respectively. The female-to-male ratio of the recombination rate was approximately 1.07:1 in adjacent microsatellite markers. This paper presents the first genetic linkage map of microsatellites in black rockfish. The collection of polymorphic markers and sex-specific linkage maps of black rockfish could be useful for further investigations on parental assignment, population genetics, quantitative trait loci mapping, and marker-assisted selection in related breeding programs.

  6. Privacy-preserving record linkage on large real world datasets.

    Science.gov (United States)

    Randall, Sean M; Ferrante, Anna M; Boyd, James H; Bauer, Jacqueline K; Semmens, James B

    2014-08-01

    Record linkage typically involves the use of dedicated linkage units who are supplied with personally identifying information to determine individuals from within and across datasets. The personally identifying information supplied to linkage units is separated from clinical information prior to release by data custodians. While this substantially reduces the risk of disclosure of sensitive information, some residual risks still exist and remain a concern for some custodians. In this paper we trial a method of record linkage which reduces privacy risk still further on large real world administrative data. The method uses encrypted personal identifying information (bloom filters) in a probability-based linkage framework. The privacy preserving linkage method was tested on ten years of New South Wales (NSW) and Western Australian (WA) hospital admissions data, comprising in total over 26 million records. No difference in linkage quality was found when the results were compared to traditional probabilistic methods using full unencrypted personal identifiers. This presents as a possible means of reducing privacy risks related to record linkage in population level research studies. It is hoped that through adaptations of this method or similar privacy preserving methods, risks related to information disclosure can be reduced so that the benefits of linked research taking place can be fully realised. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. Student-Teacher Linkage Verification: Model Process and Recommendations

    Science.gov (United States)

    Watson, Jeffery; Graham, Matthew; Thorn, Christopher A.

    2012-01-01

    As momentum grows for tracking the role of individual educators in student performance, school districts across the country are implementing projects that involve linking teachers to their students. Programs that link teachers to student outcomes require a verification process for student-teacher linkages. Linkage verification improves accuracy by…

  8. Industrial linkage and the segmented economy: 1. Some theortical proposals

    OpenAIRE

    Taylor, M. J.; Thrift, N. J.

    1982-01-01

    This paper, the first of two, reinterprets linkage studies as part of a geography of business organisations based on the power relationships between different segments of an industrial economy. Linkage studies are reviewed and found to lack any depth of explanation. An alternative approach based upon a combination of the concepts of segmentation and networks of power is then presented.

  9. Genetic linkage studies with neurofibromatosis: the question of heterogeneity.

    Science.gov (United States)

    Spence, M A; Sparkes, R S; Parry, D M; Bale, S J; Cortessis, V; Mulvihill, J J

    1987-01-01

    Three new families are reported for standard gene linkage markers and classical peripheral neurofibromatosis (Von Reckling-hausen disease). Additional data are summarised for the exclusion map. One family gives slight evidence of close linkage with the Gc locus on chromosome 4, raising again the question of possible genetic heterogeneity in NF. PMID:3118031

  10. Linkage mapping for complex traits : a regression-based approach

    NARCIS (Netherlands)

    Lebrec, Jérémie Jacques Paul

    2007-01-01

    Linkage analysis makes use of genetic markers to measure genetic similarity between relatives. By comparing this index of genetic similarity with phenotypic similarity, we can identify chromosomal regions harbouring genes involved in the architecture of a phenotype of interest. Although linkage has

  11. Lake eutrophication and its implications for organic carbon sequestration in Europe.

    Science.gov (United States)

    Anderson, N J; Bennion, H; Lotter, A F

    2014-09-01

    The eutrophication of lowland lakes in Europe by excess nitrogen (N) and phosphorus (P) is severe because of the long history of land-cover change and agricultural intensification. The ecological and socio-economic effects of eutrophication are well understood but its effect on organic carbon (OC) sequestration by lakes and its change overtime has not been determined. Here, we compile data from ~90 culturally impacted European lakes [~60% are eutrophic, Total P (TP) >30 μg P l(-1) ] and determine the extent to which OC burial rates have increased over the past 100-150 years. The average focussing corrected, OC accumulation rate (C ARFC ) for the period 1950-1990 was ~60 g C m(-2) yr(-1) , and for lakes with >100 μg TP l(-1) the average was ~100 g C m(-2) yr(-1) . The ratio of post-1950 to 1900-1950 C AR is low (~1.5) indicating that C accumulation rates have been high throughout the 20th century. Compared to background estimates of OC burial (~5-10 g C m(-2) yr(-1) ), contemporary rates have increased by at least four to fivefold. The statistical relationship between C ARFC and TP derived from this study (r(2) = 0.5) can be used to estimate OC burial at sites lacking estimates of sediment C-burial. The implications of eutrophication, diagenesis, lake morphometry and sediment focussing as controls of OC burial rates are considered. A conservative interpretation of the results of the this study suggests that lowland European meso- to eutrophic lakes with >30 μg TP l(-1) had OC burial rates in excess of 50 g C m(-2) yr(-1) over the past century, indicating that previous estimates of regional lake OC burial have seriously underestimated their contribution to European carbon sequestration. Enhanced OC burial by lakes is one positive side-effect of the otherwise negative impact of the anthropogenic disruption of nutrient cycles. © 2014 John Wiley & Sons Ltd.

  12. Lake eutrophication and brownification downgrade availability and transfer of essential fatty acids for human consumption.

    Science.gov (United States)

    Taipale, S J; Vuorio, K; Strandberg, U; Kahilainen, K K; Järvinen, M; Hiltunen, M; Peltomaa, E; Kankaala, P

    2016-11-01

    Fish are an important source of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) for birds, mammals and humans. In aquatic food webs, these highly unsaturated fatty acids (HUFA) are essential for many physiological processes and mainly synthetized by distinct phytoplankton taxa. Consumers at different trophic levels obtain essential fatty acids from their diet because they cannot produce these sufficiently de novo. Here, we evaluated how the increase in phosphorus concentration (eutrophication) or terrestrial organic matter inputs (brownification) change EPA and DHA content in the phytoplankton. Then, we evaluated whether these changes can be seen in the EPA and DHA content of piscivorous European perch (Perca fluviatilis), which is a widely distributed species and commonly consumed by humans. Data from 713 lakes showed statistically significant differences in the abundance of EPA- and DHA-synthesizing phytoplankton as well as in the concentrations and content of these essential fatty acids among oligo-mesotrophic, eutrophic and dystrophic lakes. The EPA and DHA content of phytoplankton biomass (mgHUFAg -1 ) was significantly lower in the eutrophic lakes than in the oligo-mesotrophic or dystrophic lakes. We found a strong significant correlation between the DHA content in the muscle of piscivorous perch and phytoplankton DHA content (r=0.85) as well with the contribution of DHA-synthesizing phytoplankton taxa (r=0.83). Among all DHA-synthesizing phytoplankton this correlation was the strongest with the dinoflagellates (r=0.74) and chrysophytes (r=0.70). Accordingly, the EPA+DHA content of perch muscle decreased with increasing total phosphorus (r 2 =0.80) and dissolved organic carbon concentration (r 2 =0.83) in the lakes. Our results suggest that although eutrophication generally increase biomass production across different trophic levels, the high proportion of low-quality primary producers reduce EPA and DHA content in the food web up to predatory fish

  13. Effects of eutrophication and temperature on submersed rooted plants

    DEFF Research Database (Denmark)

    Raun, Ane-Marie Løvendahl

    , especially at high temperatures. Results also showed that growth of Z. marina plants at higher temperatures will be reduced at gradually lower oxygen concentrations. The tropical seagrasses were surprisingly tolerant to oxygen depletion in the water column and none of them showed reduced growth within the 72......Aquatic macrophytes have during the last decades faced a massive decline of coverage and repeated die‐off events have been detected for freshwater (Sand‐Jensen et al., 2000) and marine plants (Waycott et al., 2009). Increased nutrient loading has been suggested to play a central role, because high...... and degradation of dying alga blooms accelerate the microbial activity and thereby intensify oxygen consumption in sediment and water column. This oxygen consumption may accelerate further by increasing temperature caused by warmer climate. This thesis examines how low sediment and water column oxygen levels...

  14. Can nutrient pathways and biotic interactions control eutrophication in riverine ecosystems? Evidence from a model driven mesocosm experiment.

    Science.gov (United States)

    Jäger, Christoph G; Hagemann, Jeske; Borchardt, Dietrich

    2017-05-15

    Ecological theory predicts that the relative importance of benthic to planktonic primary production usually changes along the rivers' continuum from a predomination of benthic algae in lower stream orders to a predomination of planktonic algae at higher orders. Underlying mechanisms driving the interaction between algae in these habitats, its controlling factors and consequences for riverine ecosystems are, however, only partly understood. We present a mechanistic analysis of the governing ecological processes using a simplified, numerical model and examine how abiotic factors and biotic interactions influence benthic and planktonic algae by changing resource competition. We compare the outcome of the model with the results of a factorial mesocosm experiment mimicking the parameter spaces of the model. The results show a remarkable similarity with regard to the temporal development of benthic and pelagic algal biomass and shifting dominance patterns. In particular we analyse the effects of the pathways of nutrient supply (upwelling from the hyporheic zone, direct supply to the surface water, or via both pathways) and grazing in a gradient of river depths. Our results show that detachment of benthic algae, sinking of planktonic algae and the pathway of nutrient supply are key processes determining the respective algal biomass distributions particularly in shallow and intermediate deep systems. Increasing nutrient supply increases algal biomasses, but does not change the general pattern of the interactions. Decreasing light supply decreases the dominance of planktonic algae, but increases dissolved nutrients. At intermediate to high grazing rates algal biomass can be controlled by grazers, but however, at high grazing rates, dissolved nutrients accumulate in the surface water. Our results indicate that nutrient pathways, resource competition and internal control by grazing need to be considered explicitly for the understanding and explanation of eutrophication

  15. The first-generation Daphnia magna linkage map

    Directory of Open Access Journals (Sweden)

    De Meester Luc

    2010-09-01

    Full Text Available Abstract Background Daphnia magna is a well-established model species in ecotoxicology, ecology and evolution. Several new genomics tools are presently under development for this species; among them, a linkage map is a first requirement for estimating the genetic background of phenotypic traits in quantitative trait loci (QTL studies and is also very useful in assembling the genome. It also enables comparative studies between D. magna and D. pulex, for which a linkage map already exists. Results Here we describe the first genetic linkage map of D. magna. We generated 214 F2 (intercross clonal lines as the foundation of the linkage analysis. The linkage map itself is based on 109 microsatellite markers, which produced ten major linkage groups ranging in size from 31.1 cM to 288.5 cM. The total size of this linkage map extends to 1211.6 Kosambi cM, and the average interval for the markers within linkage groups is 15.1 cM. The F2 clones can be used to map QTLs for traits that differ between the parental clones. We successfully mapped the location of two loci with infertility alleles, one inherited from the paternal clone (Iinb1 and the other from the maternal clone (Xinb3. Conclusions The D. magna linkage map presented here provides extensive coverage of the genome and a given density of markers that enable us to detect QTLs of moderate to strong effects. It is similar in size to the linkage map of D. pulex.

  16. Are Birth Certificate and Hospital Discharge Linkages Performed in 52 Jurisdictions in the United States?

    OpenAIRE

    Kim, Shin Y.; Ahuja, Sukhjeet; Stampfel, Caroline; Williamson, Dhelia

    2015-01-01

    Objectives The purpose of this study was to determine the number and characteristics of US State Registrars of Vital Statistics (Vital Registrars) and State Systems Development Initiative (SSDI) Coordinators that link birth certificate and hospital discharge data as well as using linkage processes. Methods Vital Registrars and SSDI Coordinators in all 52 vital records jurisdictions (50 states, District of Columbia, and New York City) were asked to complete a 41-question survey. We examined fr...

  17. Mapping of yield, yield stability, yield adaptability and other traits in barley using linkage disequilibrium mapping and linkage analysis

    NARCIS (Netherlands)

    Kraakman, A.T.W.

    2005-01-01

    Plants is mostly done through linkage analysis. A segregating mapping population Identification and mappping of Quantitative Trait Loci (QTLs) in is created from a bi-parental cross and linkages between trait values and mapped markers reveal the positions ofQTLs. In

  18. Mapping of yield, yield stability, yield adaptability and other traits in barley using linkage disequilibrium mapping and linkage analysis

    OpenAIRE

    Kraakman, A.T.W.

    2005-01-01

    Plants is mostly done through linkage analysis. A segregating mapping population Identification and mappping of Quantitative Trait Loci (QTLs) in is created from a bi-parental cross and linkages between trait values and mapped markers reveal the positions ofQTLs. Inthisstudyweexploredlinkagedisequilibrium(LD)mappingof traits in a set of modernbarleycultivars. LDbetweenmolecularmarkerswasfoundup to a distance of 10 centimorgan,whichislargecomparedtootherspecies.Thelarge distancemightbeinducedb...

  19. [MapDraw: a microsoft excel macro for drawing genetic linkage maps based on given genetic linkage data].

    Science.gov (United States)

    Liu, Ren-Hu; Meng, Jin-Ling

    2003-05-01

    MAPMAKER is one of the most widely used computer software package for constructing genetic linkage maps.However, the PC version, MAPMAKER 3.0 for PC, could not draw the genetic linkage maps that its Macintosh version, MAPMAKER 3.0 for Macintosh,was able to do. Especially in recent years, Macintosh computer is much less popular than PC. Most of the geneticists use PC to analyze their genetic linkage data. So a new computer software to draw the same genetic linkage maps on PC as the MAPMAKER for Macintosh to do on Macintosh has been crying for. Microsoft Excel,one component of Microsoft Office package, is one of the most popular software in laboratory data processing. Microsoft Visual Basic for Applications (VBA) is one of the most powerful functions of Microsoft Excel. Using this program language, we can take creative control of Excel, including genetic linkage map construction, automatic data processing and more. In this paper, a Microsoft Excel macro called MapDraw is constructed to draw genetic linkage maps on PC computer based on given genetic linkage data. Use this software,you can freely construct beautiful genetic linkage map in Excel and freely edit and copy it to Word or other application. This software is just an Excel format file. You can freely copy it from ftp://211.69.140.177 or ftp://brassica.hzau.edu.cn and the source code can be found in Excel's Visual Basic Editor.

  20. Impacts of the 2011 Tsunami on Sediment Characteristics and Macrozoobenthic Assemblages in a Shallow Eutrophic Lagoon, Sendai Bay, Japan.

    Directory of Open Access Journals (Sweden)

    Gen Kanaya

    Full Text Available A huge tsunami is one of the greatest disturbance events in coastal benthic communities, although the ecological consequences are not fully understood. Here we examined the tsunami-induced changes in the sediment environment and macrozoobenthic assemblage in a eutrophic brackish lagoon in eastern Japan. The 7.2-m-high tsunami completely replaced muddy sediment with drifting sea sand throughout the lagoon, leading to the drastic changes in quantity and quality of sedimental organic matters, sulfide contents, and sediment redox condition. Intensive physical stress devastated the benthic community, but the disappearance of sulfidic muddy bottoms significantly improved the habitat quality for macrozoobenthos. The re-established macrozoobenthic community after 5 months was characterized by (1 a 2-fold higher total density, but sharp declines in species richness, diversity, and evenness; (2 an increased density of opportunistic taxa (e.g., polychaete Pseudopolydora spp. and amphipod Monocorophium uenoi in newly created sandy bottoms; and (3 disappearance of several dominant taxa including bivalves and chironomid larvae. These findings indicate that the sensitivity and recovery potential of macrozoobenthos were highly taxa-specific, which was closely related to the taxa's ecological characteristics, including tolerance to physical disturbance, life-history traits, and life form. Our data revealed the rapid recolonization of opportunistic macrozoobenthos after a huge tsunami, which would contribute to the functional recovery of estuarine soft-bottom habitats shortly after a disturbance event.

  1. Assessment of resuspended matter and redistribution of macronutrient elements produced by boat disturbance in a eutrophic lagoon.

    Science.gov (United States)

    Lenzi, Mauro; Finoia, Maria Grazia; Gennaro, Paola; Mercatali, Isabel; Persia, Emma; Solari, Jacopo; Porrello, Salvatore

    2013-07-15

    Harvesting of macroalgae by specially equipped boats in a shallow eutrophic lagoon produces evident sediment resuspension. To outline the environmental effects of this disturbance, we examined the quantity of fall-out and the distances travelled by sediment and macronutrients from the source of boat disturbance. Resuspended sediment fall-out (RSFO) was trapped at different distances from the boat path to determine total dry weight, total nitrogen (TN), total carbon (TC), total organic carbon (TOC), total sulphur (TS) and total phosphorus (TP). The data was analysed by principal components analysis (PCA) and linear discriminant analysis (LDA) on PCA factors. Fall-out of C, N, S and P from the plume of resuspended sediment indicated significant re-arrangement of these nutrients: RSFO dry weight and S content decreased with distance from the boat path, whereas TP increased and was the variable responsible for most discrimination at 100 m. The mass of resuspended matter was relatively large, indicating that the boats considerably reshuffle lagoon sediment. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. First report on Noctiluca scintillans blooms in the Red Sea off the coasts of Saudi Arabia: consequences of eutrophication

    Directory of Open Access Journals (Sweden)

    Ibrahim Mesaad

    2007-09-01

    Full Text Available Blooms of Noctiluca scintillans are reported for the first time in the Red Sea offthe south-western coasts of Saudi Arabia. During the present study, surface water samples werecollected weekly on the coasts of the Al Shuqayq region from February to April 2004-2006. The abundance of N. scintillans correlated negatively with most nutrients,as well as the cell densities of diatoms and dinoflagellate species. Microscopic examination of live cells from Noctiluca blooms showed the presence of some species of diatoms and dinoflagellates within the Noctiluca body - confirmation of its grazing on these microalgae algae. Thepresence of a Noctiluca bloom in the coastal waters off south-western Saudi Arabia could be linked indirectly to water eutrophication by an increase in prey abundance.The physico-chemical properties of Red Sea coastal waters should therefore be monitored regularly in order to minimize the formation of harmful algal blooms, which may affect all food web levels, including the human level.

  3. Impacts of the 2011 Tsunami on Sediment Characteristics and Macrozoobenthic Assemblages in a Shallow Eutrophic Lagoon, Sendai Bay, Japan.

    Science.gov (United States)

    Kanaya, Gen; Suzuki, Takao; Kikuchi, Eisuke

    2015-01-01

    A huge tsunami is one of the greatest disturbance events in coastal benthic communities, although the ecological consequences are not fully understood. Here we examined the tsunami-induced changes in the sediment environment and macrozoobenthic assemblage in a eutrophic brackish lagoon in eastern Japan. The 7.2-m-high tsunami completely replaced muddy sediment with drifting sea sand throughout the lagoon, leading to the drastic changes in quantity and quality of sedimental organic matters, sulfide contents, and sediment redox condition. Intensive physical stress devastated the benthic community, but the disappearance of sulfidic muddy bottoms significantly improved the habitat quality for macrozoobenthos. The re-established macrozoobenthic community after 5 months was characterized by (1) a 2-fold higher total density, but sharp declines in species richness, diversity, and evenness; (2) an increased density of opportunistic taxa (e.g., polychaete Pseudopolydora spp. and amphipod Monocorophium uenoi) in newly created sandy bottoms; and (3) disappearance of several dominant taxa including bivalves and chironomid larvae. These findings indicate that the sensitivity and recovery potential of macrozoobenthos were highly taxa-specific, which was closely related to the taxa's ecological characteristics, including tolerance to physical disturbance, life-history traits, and life form. Our data revealed the rapid recolonization of opportunistic macrozoobenthos after a huge tsunami, which would contribute to the functional recovery of estuarine soft-bottom habitats shortly after a disturbance event.

  4. Young people’s views about consenting to data linkage: findings from the PEARL qualitative study

    Directory of Open Access Journals (Sweden)

    Suzanne Audrey

    2016-03-01

    Full Text Available Abstract Background Electronic administrative data exist in several domains which, if linked, are potentially useful for research. However, benefits from data linkage should be considered alongside risks such as the threat to privacy. Avon Longitudinal Study of Parents and Children (ALSPAC is a birth cohort study. The Project to Enhance ALSPAC through Record Linkage (PEARL was established to enrich the ALSPAC resource through linkage between ALSPAC participants and routine sources of health and social data. Qualitative research was incorporated in the PEARL study to examine participants’ views about data linkage and inform approaches to information sharing. This paper focusses on issues of consent. Methods Digitally recorded interviews were conducted with 55 participants aged 17–19 years. Terms and processes relating to consent, anonymization and data linkage were explained to interviewees. Scenarios were used to prompt consideration of linking different sources of data, and whether consent should be requested. Interview recordings were fully transcribed. Thematic analysis was undertaken using the Framework approach. Results Participant views on data linkage appeared to be most influenced by: considerations around the social sensitivity of the research question, and; the possibility of tangible health benefits in the public interest. Some participants appeared unsure about the effectiveness of anonymization, or did not always view effective anonymization as making consent unnecessary. This was related to notions of ownership of personal information and etiquette around asking permission for secondary use. Despite different consent procedures being explained, participants tended to equate consent with ‘opt-in’ consent through which participants are ‘asked’ if their data can be used for a specific study. Participants raising similar concerns came to differing conclusions about whether consent was needed. Views changed when presented

  5. ANALYSIS OF INTER SECTORAL LINKAGES IN SEMARANG REGENCY

    Directory of Open Access Journals (Sweden)

    Fafurida

    2014-03-01

    Full Text Available This research aims to analyze inter economic sectoral linkages and to arrange the Klassen typology of economic sectors in Semarang Regency. The Klassen typology is composed from the result of the linkage analysis. To construct the analysis, this paper also utulizes the input-output analysis. It finds that service sector has the highest backward linkage while farming sector has the highest forward linkage. Based on the Klassen typology analysis, sectors with the highest backward and forward linkages and potential to be the leading sector are farming sector, dan trade, hotel and restaurant sector.Keywords: Backward linkage,forward linkage, Klassen typologyJEL classification number: R15, O21AbstrakPenelitian ini bertujuan untuk mengkaji seberapa besar keterkaitan antar sektor ekonomi di Kabupaten Semarang dan memetakan tipologi Klassennya. Tipologi Klasen disusun berdasarkan hasil perhitungan analisis keterkaitannya. Untuk menyusun analisis tersebut, paper ini juga menggunakan analisis input-output. Hasil penelitian menunjukkan bahwa sektor jasa memiliki keterkaitan ke belakang tertinggi dibandingkan dengan sektor lainnya. Sementara itu, sektor pertanian merupakan sektor yang memiliki keterkaitan ke depan tertinggi. Berdasarkan hasil analisis tipologi Klassen, sektor yang memiliki keterkaitan ke depan dan ke belakang yang tinggi dan dapat menjadi sektor unggulan adalah sektor perdagangan, hotel dan sektor restoran.Kata kunci: Keterkaitan ke belakang, keterkaitan ke depan, tipologi KlassenJEL classification numbers: R15, O21

  6. A transparent and transportable methodology for evaluating Data Linkage software.

    Science.gov (United States)

    Ferrante, Anna; Boyd, James

    2012-02-01

    There has been substantial growth in Data Linkage (DL) activities in recent years. This reflects growth in both the demand for, and the supply of, linked or linkable data. Increased utilisation of DL "services" has brought with it increased need for impartial information about the suitability and performance capabilities of DL software programs and packages. Although evaluations of DL software exist; most have been restricted to the comparison of two or three packages. Evaluations of a large number of packages are rare because of the time and resource burden placed on the evaluators and the need for a suitable "gold standard" evaluation dataset. In this paper we present an evaluation methodology that overcomes a number of these difficulties. Our approach involves the generation and use of representative synthetic data; the execution of a series of linkages using a pre-defined linkage strategy; and the use of standard linkage quality metrics to assess performance. The methodology is both transparent and transportable, producing genuinely comparable results. The methodology was used by the Centre for Data Linkage (CDL) at Curtin University in an evaluation of ten DL software packages. It is also being used to evaluate larger linkage systems (not just packages). The methodology provides a unique opportunity to benchmark the quality of linkages in different operational environments. Copyright © 2011 Elsevier Inc. All rights reserved.

  7. Linkage analysis in familial Angelman syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Wagstaff, J. (Harvard Medical School, Boston, MA (United States)); Shugart, Y.Y. (Columbia Univ., New York (United States)); Lalande, M. (Harvard Medical School, Boston, MA (United States) Howard Hughes Medical Institute, Boston, MA (United States))

    1993-07-01

    Familial Angelman syndrome (AS) can result from mutations in chromosome 15q11q13 that, when transmitted from father to child, result in no phenotypic abnormality but, when transmitted from mother to child, cause AS. These mutations therefore behave neither as dominant nor as recessive mutations but, rather, show an imprinted mode of inheritance. The authors have analyzed two sibling pairs with AS and a larger family with four AS offspring of three sisters with several recently described microsatellite polymorphisms in the AS region. AS siblings inherited the same maternal alleles at the GABRB3 and GABRA5 loci, and the unaffected siblings of AS individuals inherited the other maternal alleles at these loci. In one of the AS sibling pairs, analysis of a recombination event indicates that the mutation responsible for AS is distal to locus D15S63. This result is consistent with a previously described imprinted submicroscopic deletion causing AS, a deletion that includes loci D15S10, D15S113, and GABRB3, all distal to D15S63. The analysis of the larger AS family provides the first clear demonstration of a new mutation in nondeletion AS. Analysis of linkage of AS to GABRB3 in these three families, on the assumption of imprinted inheritance (i.e., penetrance of an AS mutation is 1 if transmitted maternally and is 0 if transmitted paternally), indicates a maximum lod score of 3.52 at 6 = 0. 34 refs., 4 figs., 1 tab.

  8. Optimal sampling strategies for detecting linkage of a complex trait with known genetic heterogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Easton, D.F. [Institute of Cancer Research, Sutton (United Kingdom); Goldgar, D.E. [Univ. of Utah, Salt Lake City (United States)

    1994-09-01

    As genes underlying susceptibility to human disease are identified through linkage analysis, it is becoming increasingly clear that genetic heterogeneity is the rule rather than the exception. The focus of the present work is to examine the power and optimal sampling design for localizing a second disease gene when one disease gene has previously been identified. In particular, we examined the case when the unknown locus had lower penetrance, but higher frequency, than the known locus. Three scenarios regarding knowledge about locus 1 were examined: no linkage information (i.e. standard heterogeneity analysis), tight linkage with a known highly polymorphic marker locus, and mutation testing. Exact expected LOD scores (ELODs) were calculated for a number of two-locus genetic models under the 3 scenarios of heterogeneity for nuclear families containing 2, 3 or 4 affected children, with 0 or 1 affected parents. A cost function based upon the cost of ascertaining and genotyping sufficient samples to achieve an ELOD of 3.0 was used to evaluate the designs. As expected, the power and the optimal pedigree sampling strategy was dependent on the underlying model and the heterogeneity testing status. When the known locus had higher penetrance than the unknown locus, three affected siblings with unaffected parents proved to be optimal for all levels of heterogeneity. In general, mutation testing at the first locus provided substantially more power for detecting the second locus than linkage evidence alone. However, when both loci had relatively low penetrance, mutation testing provided little improvement in power since most families could be expected to be segregating the high risk allele at both loci.

  9. Bayesian linkage and segregation analysis: factoring the problem.

    Science.gov (United States)

    Matthysse, S

    2000-01-01

    Complex segregation analysis and linkage methods are mathematical techniques for the genetic dissection of complex diseases. They are used to delineate complex modes of familial transmission and to localize putative disease susceptibility loci to specific chromosomal locations. The computational problem of Bayesian linkage and segregation analysis is one of integration in high-dimensional spaces. In this paper, three available techniques for Bayesian linkage and segregation analysis are discussed: Markov Chain Monte Carlo (MCMC), importance sampling, and exact calculation. The contribution of each to the overall integration will be explicitly discussed.

  10. Assessing threshold values for eutrophication management using Bayesian method in Yuqiao Reservoir, North China.

    Science.gov (United States)

    Li, Xue; Xu, Yuan; Zhao, Gang; Shi, Chunli; Wang, Zhong-Liang; Wang, Yuqiu

    2015-04-01

    The eutrophication problem of drinking water source is directly related to the security of urban water supplication, and phosphorus has been proved as an important element to the water quality of the most northern hemisphere lakes and reservoirs. In the paper, 15-year monitoring records (1990∼2004) of Yuqiao Reservoir were used to model the changing trend of the total phosphorus (TP), analyze the uncertainty of nutrient parameters, and estimate the threshold of eutrophication management at a specific water quality goal by the application of Bayesian method through chemical material balance (CMB) model. The results revealed that Yuqiao Reservoir was a P-controlled water ecosystem, and the inner concentration of TP in the reservoir was significantly correlated with TP loading concentration, hydraulic retention coefficient, and bottom water dissolved oxygen concentration. In the case, the goal of water quality for TP in the reservoir was set to be 0.05 mg L(-1) (the third level of national surface water standard for reservoirs according to GB3838-2002), management measures could be taken to improve water quality in reservoir through controlling the highest inflow phosphorus concentration (0.15∼0.21 mg L(-1)) and the lowest DO concentration (3.76∼5.59 mg L(-1)) to the threshold. Inverse method was applied to evaluate the joint manage measures, and the results revealed that it was a valuable measure to avoid eutrophication by controlling lowest dissolved oxygen concentration and adjusting the inflow and outflow of reservoir.

  11. ECO: A Generic Eutrophication Model Including Comprehensive Sediment-Water Interaction

    Science.gov (United States)

    Smits, Johannes G. C.; van Beek, Jan K. L.

    2013-01-01

    The content and calibration of the comprehensive generic 3D eutrophication model ECO for water and sediment quality is presented. Based on a computational grid for water and sediment, ECO is used as a tool for water quality management to simulate concentrations and mass fluxes of nutrients (N, P, Si), phytoplankton species, detrital organic matter, electron acceptors and related substances. ECO combines integral simulation of water and sediment quality with sediment diagenesis and closed mass balances. Its advanced process formulations for substances in the water column and the bed sediment were developed to allow for a much more dynamic calculation of the sediment-water exchange fluxes of nutrients as resulting from steep concentration gradients across the sediment-water interface than is possible with other eutrophication models. ECO is to more accurately calculate the accumulation of organic matter and nutrients in the sediment, and to allow for more accurate prediction of phytoplankton biomass and water quality in response to mitigative measures such as nutrient load reduction. ECO was calibrated for shallow Lake Veluwe (The Netherlands). Due to restoration measures this lake underwent a transition from hypertrophic conditions to moderately eutrophic conditions, leading to the extensive colonization by submerged macrophytes. ECO reproduces observed water quality well for the transition period of ten years. The values of its process coefficients are in line with ranges derived from literature. ECO’s calculation results underline the importance of redox processes and phosphate speciation for the nutrient return fluxes. Among other things, the results suggest that authigenic formation of a stable apatite-like mineral in the sediment can contribute significantly to oligotrophication of a lake after a phosphorus load reduction. PMID:23844160

  12. Algal bloom sedimentation induces variable control of lake eutrophication by phosphorus inactivating agents

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Changhui [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China); Bai, Leilei [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China); Graduate University of Chinese Academy of Sciences (China); Jiang, He-Long, E-mail: hljiang@niglas.ac.cn [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China); Xu, Huacheng [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China)

    2016-07-01

    Lake eutrophication typically occurs with a syndrome of algae breeding and biomass accumulation (e.g., algal blooms). Therefore, the effect of algal bloom sedimentation on eutrophication control by phosphorus (P) inactivating agents was assessed herein. Three commercial products, including aluminum (Al) sulfate, iron (Fe) sulfate, and a lanthanum-modified clay (Phoslock®), as well as one easily available by-product, drinking water treatment residue (DWTR), were selected. The most important finding was that during algae sedimentation, P immobilization from the overlying water by Al, Phoslock®, and DWTR was dominated by a long-term slow phase (> 150 d), while Fe has limited effectiveness on the immobilization. Further analysis indicated that the algae sedimentation effect was mainly due to the slow release of P from algae, leading to relatively limited P available for the inactivating agents. Then, a more unfavorable effect on the P immobilization capability of inactivating agents was caused by the induced anaerobic conditions, the released organic matter from algae, and the increased sulfide in the overlying water and sediments during sedimentation. Overall, algae sedimentation induced variable control of eutrophication by P inactivating agents. Accordingly, recommendations for future works about algal lake restoration were also proposed. - Highlights: • A long-term P immobilization by Phoslock®, DWTR, and Al was observed. • Fe had limited effectiveness on P pollution control for overlying water. • Al and Fe enhanced sulfur reduction, while DWTR and Phoslock® had minor effect. • The sedimentation reduced Al and La release from agents, but enhanced Fe release. • The agents changed organic matter compositions and structures in water columns.

  13. Eutrophication and nutrient release in urban areas of sub-Saharan Africa--a review.

    Science.gov (United States)

    Nyenje, P M; Foppen, J W; Uhlenbrook, S; Kulabako, R; Muwanga, A

    2010-01-01

    Eutrophication is an increasing problem in sub-Saharan Africa (SSA), and, as a result, the ecological integrity of surface waters becomes compromised, fish populations become extinct, toxic cyanobacteria blooms are abundant, and oxygen levels reduce. In this review we establish the relationship between eutrophication of fresh inland surface waters in SSA and the release of nutrients in their mega-cities. Monitoring reports indicate that the population of mega-cities in SSA is rapidly increasing, and so is the total amount of wastewater produced. Of the total amounts produced, at present, less than 30% is treated in sewage treatment plants, while the remainder is disposed of via onsite sanitation systems, eventually discharging their wastewater into groundwater. When related to the urban water balance of a number of SSA cities, the total amount of wastewater produced may be as high as 10-50% of the total precipitation entering these urban areas, which is considerable, especially since in most cases, precipitation is the most important, if not only the 'wastewater diluting agent' present. The most important knowledge gaps include: (1) the fate and transport mechanisms of nutrients (N and P) in soils and aquifers, or, conversely, the soil aquifer treatment characteristics of the regoliths, which cover a large part of SSA, (2) the effect of the episodic and largely uncontrolled removal of nutrients stored at urban surfaces by runoff from precipitation on nutrient budgets in adjacent lakes and rivers draining the urban areas, and (3) the hydrology and hydrogeology within the urban area, including surface water and groundwater flow patterns, transport velocities, dynamics of nutrient transport, and the presence of recharge and discharge areas. In order to make a start with managing this urban population-related eutrophication, many actions are required. As a first step, we suggest to start systematically researching the key areas identified above.

  14. Rising CO2 Levels Will Intensify Phytoplankton Blooms in Eutrophic and Hypertrophic Lakes

    Science.gov (United States)

    Verspagen, Jolanda M. H.; Van de Waal, Dedmer B.; Finke, Jan F.; Visser, Petra M.; Van Donk, Ellen; Huisman, Jef

    2014-01-01

    Harmful algal blooms threaten the water quality of many eutrophic and hypertrophic lakes and cause severe ecological and economic damage worldwide. Dense blooms often deplete the dissolved CO2 concentration and raise pH. Yet, quantitative prediction of the feedbacks between phytoplankton growth, CO2 drawdown and the inorganic carbon chemistry of aquatic ecosystems has received surprisingly little attention. Here, we develop a mathematical model to predict dynamic changes in dissolved inorganic carbon (DIC), pH and alkalinity during phytoplankton bloom development. We tested the model in chemostat experiments with the freshwater cyanobacterium Microcystis aeruginosa at different CO2 levels. The experiments showed that dense blooms sequestered large amounts of atmospheric CO2, not only by their own biomass production but also by inducing a high pH and alkalinity that enhanced the capacity for DIC storage in the system. We used the model to explore how phytoplankton blooms of eutrophic waters will respond to rising CO2 levels. The model predicts that (1) dense phytoplankton blooms in low- and moderately alkaline waters can deplete the dissolved CO2 concentration to limiting levels and raise the pH over a relatively wide range of atmospheric CO2 conditions, (2) rising atmospheric CO2 levels will enhance phytoplankton blooms in low- and moderately alkaline waters with high nutrient loads, and (3) above some threshold, rising atmospheric CO2 will alleviate phytoplankton blooms from carbon limitation, resulting in less intense CO2 depletion and a lesser increase in pH. Sensitivity analysis indicated that the model predictions were qualitatively robust. Quantitatively, the predictions were sensitive to variation in lake depth, DIC input and CO2 gas transfer across the air-water interface, but relatively robust to variation in the carbon uptake mechanisms of phytoplankton. In total, these findings warn that rising CO2 levels may result in a marked intensification of

  15. Cover of coastal vegetation as an indicator of eutrophication along environmental gradients.

    Science.gov (United States)

    Wikström, Sofia A; Carstensen, Jacob; Blomqvist, Mats; Krause-Jensen, Dorte

    2016-01-01

    Coastal vegetation communities are important for primary production, biodiversity, coastal protection, carbon and nutrient cycling which, in combination with their sensitivity to eutrophication, render them potential indicators of environmental status for environmental policies like the EU Water and Marine Strategy Framework Directives. We evaluated one potential indicator for coastal vegetation, the cumulative cover at depths where the vegetation is light limited, by investigating its response to eutrophication along gradients in natural conditions. We used a large data set covering the Swedish coastline, spanning broad gradients in nutrient level, water clarity, seabed substrate, physical exposure and climate in addition to a salinity gradient from 0.5 to 30.5. Macroalgal cover increased significantly along gradients of declining nutrient concentration and increasing water clarity when we had accounted for diver effects, spatio-temporal sampling variability, salinity gradients, wave exposure and latitude. The developed empirical model explained 79% of the variation in algal cover across 130 areas. Based on this, we identified macroalgal cover as a promising indicator across the Baltic Sea, Kattegat and Skagerrak. A parallel analysis of soft-substrate macrophytes similarly identified significant increases in cover with decreasing concentrations of total nitrogen and increasing salinity, but the resulting empirical model explained only 52% of the variation in cover, probably due to the spatially more variable nature of soft-substrate vegetation. The identified general responses of vegetation cover to gradients of eutrophication across wide ranges in environmental settings may be useful for monitoring and management of marine vegetation in areas with strong environmental gradients.

  16. ECO: a generic eutrophication model including comprehensive sediment-water interaction.

    Science.gov (United States)

    Smits, Johannes G C; van Beek, Jan K L

    2013-01-01

    The content and calibration of the comprehensive generic 3D eutrophication model ECO for water and sediment quality is presented. Based on a computational grid for water and sediment, ECO is used as a tool for water quality management to simulate concentrations and mass fluxes of nutrients (N, P, Si), phytoplankton species, detrital organic matter, electron acceptors and related substances. ECO combines integral simulation of water and sediment quality with sediment diagenesis and closed mass balances. Its advanced process formulations for substances in the water column and the bed sediment were developed to allow for a much more dynamic calculation of the sediment-water exchange fluxes of nutrients as resulting from steep concentration gradients across the sediment-water interface than is possible with other eutrophication models. ECO is to more accurately calculate the accumulation of organic matter and nutrients in the sediment, and to allow for more accurate prediction of phytoplankton biomass and water quality in response to mitigative measures such as nutrient load reduction. ECO was calibrated for shallow Lake Veluwe (The Netherlands). Due to restoration measures this lake underwent a transition from hypertrophic conditions to moderately eutrophic conditions, leading to the extensive colonization by submerged macrophytes. ECO reproduces observed water quality well for the transition period of ten years. The values of its process coefficients are in line with ranges derived from literature. ECO's calculation results underline the importance of redox processes and phosphate speciation for the nutrient return fluxes. Among other things, the results suggest that authigenic formation of a stable apatite-like mineral in the sediment can contribute significantly to oligotrophication of a lake after a phosphorus load reduction.

  17. ECO: a generic eutrophication model including comprehensive sediment-water interaction.

    Directory of Open Access Journals (Sweden)

    Johannes G C Smits

    Full Text Available The content and calibration of the comprehensive generic 3D eutrophication model ECO for water and sediment quality is presented. Based on a computational grid for water and sediment, ECO is used as a tool for water quality management to simulate concentrations and mass fluxes of nutrients (N, P, Si, phytoplankton species, detrital organic matter, electron acceptors and related substances. ECO combines integral simulation of water and sediment quality with sediment diagenesis and closed mass balances. Its advanced process formulations for substances in the water column and the bed sediment were developed to allow for a much more dynamic calculation of the sediment-water exchange fluxes of nutrients as resulting from steep concentration gradients across the sediment-water interface than is possible with other eutrophication models. ECO is to more accurately calculate the accumulation of organic matter and nutrients in the sediment, and to allow for more accurate prediction of phytoplankton biomass and water quality in response to mitigative measures such as nutrient load reduction. ECO was calibrated for shallow Lake Veluwe (The Netherlands. Due to restoration measures this lake underwent a transition from hypertrophic conditions to moderately eutrophic conditions, leading to the extensive colonization by submerged macrophytes. ECO reproduces observed water quality well for the transition period of ten years. The values of its process coefficients are in line with ranges derived from literature. ECO's calculation results underline the importance of redox processes and phosphate speciation for the nutrient return fluxes. Among other things, the results suggest that authigenic formation of a stable apatite-like mineral in the sediment can contribute significantly to oligotrophication of a lake after a phosphorus load reduction.

  18. Contribution of primary producers to mercury trophic transfer in estuarine ecosystems: possible effects of eutrophication.

    Science.gov (United States)

    Coelho, J P; Pereira, M E; Duarte, A C; Pardal, M A

    2009-08-01

    There is an ongoing eutrophication process in the Ria de Aveiro coastal lagoon (Portugal), with progressive replacement of rooted primary producers for macroalgae. Taking advantage of a well-defined environmental contamination gradient, we studied mercury accumulation and distribution in the aboveground and the belowground biomass of several salt marsh plants, including the seagrass species Zostera noltii and the dominant green macroalgal species Enteromorpha sp. The results of these experiments were then placed into the context of the estuarine mercury cycle and transport from the contaminated area. All salt marsh plants accumulated mercury in the root system, with Halimione portulacoides showing the highest levels, with up to 1.3 mg kg(-1) observed in the most contaminated area. Belowground/aboveground ratios were generally below 0.4, suggesting that salt marsh plants are efficient immobilizers and retainers of mercury agents. Moreover, due to their sediment accretion capacities, salt marsh plants seem to play an important role in the sequestration of mercury in estuarine sediments. Seagrasses, on the other hand, accumulated considerable amounts of mercury in the aboveground biomass with belowground/aboveground ratios reaching as high as 1.4. These results may be due to their different routes of uptake (roots and foliar uptake) which suggests that seagrass meadows can be an important agent in the export of mercury from contaminated areas, considering the high aboveground biomass replacement rates. Rooted macrophytes accumulate less mercury in their aboveground biomass than macroalgae. The change of primary producer dominance due to eutrophication can originate a 4- to 5-fold increase in primary producer associated mercury. This mercury would be available for export, making it bioavailable to estuarine food webs, which stresses the need to reverse the current eutrophic status of estuarine systems.

  19. Food web structure of two Mediterranean lagoons under varying degree of eutrophication

    Science.gov (United States)

    Carlier, Antoine; Riera, Pascal; Amouroux, Jean-Michel; Bodiou, Jean-Yves; Desmalades, Martin; Grémare, Antoine

    2008-11-01

    The food web structure and functioning of two north-western Mediterranean lagoons exhibiting contrasting degrees of eutrophication and marine influences were compared through δ13C and δ15N analysis of major potential food sources and consumers. The Lapalme Lagoon is well preserved and has kept a natural and temporary connection with the open sea. Conversely, the Canet Lagoon is heavily eutrophicated and its water exchange with the open sea has been artificially reduced. In Lapalme, all potential food sources and consumers exhibited δ15N values indicative of pristine coastal areas. Suspended particulate organic matter (POM) and sediment organic matter (SOM) pools seemed to constitute the main food sources of most primary consumers. Both primary producers and all consumers were much more 15N-enriched (by ˜ 10‰) and more 13C-depleted in Canet than in Lapalme. This reflected: (1) the assimilation of important amounts of anthropogenic nitrogen in the food web, and (2) a marked and uniform influence of 13C-depleted allochtonous sources of carbon. Based on the mean δ15N of primary consumers, we found rather similar food web lengths in both lagoons with top consumers at trophic levels 3.6 and 4.0 in Canet and Lapalme, respectively. However, the eutrophication of the Canet Lagoon resulted in a simplification of the food web structure (i.e., a single trophic pathway from a 15N-enriched fraction of the SOM pool to top predators) compared to what was observed in Lapalme Lagoon where additional 13C-enriched food sources played a significant trophic role. Moreover, some consumers of Canet tended to exploit primary producers to a larger extent (and thus to exhibit lower trophic levels) than in Lapalme.

  20. Diversity and abundance of ammonia-oxidizing bacteria in eutrophic and oligotrophic basins of a shallow Chinese lake (Lake Donghu).

    Science.gov (United States)

    Chen, Guo-Yuan; Qiu, Shan-Lian; Zhou, Yi-Yong

    2009-04-01

    Classical cultivation and molecular methods based on the ammonia monooxygenase gene (amoA) were used to study the abundance and diversity of beta-proteobacterial ammonia-oxidizing bacteria (AOB) in lake sediments. The eutrophic and oligotrophic basins of a Chinese shallow lake (Lake Donghu), in terms of ammonium (NH(+)(4)) concentrations, were sampled. The AOB number was significantly lower in the oligotrophic basin, but significantly higher in the eutrophic basin. In addition, using restriction fragment length polymorphism targeting the amoA, ten restriction patterns including six unique ones were found in the eutrophic basin, while five patterns were observed in the oligotrophic basin with only one unique restriction group. Phylogenetic analysis for AOB revealed that Nitrosomonas oligotropha- and Nitrosomonas ureae-related AOB and Nitrosospira-affiliated AOB were ubiquitous; the former dominated in the eutrophic basin (87.2%), while the latter dominated in the oligotrophic basin (65.5%). Furthermore, Nitrosomonas communis-related AOB was only detected in the eutrophic basin, at a small proportion (3.2%). These results indicate significant selection and adaptation of sediment AOB in lakes with differing trophic status.

  1. Sedimentary organic and inorganic records of eutrophication and hypoxia in and off the Changjiang Estuary over the last century.

    Science.gov (United States)

    Zhao, Jun; Feng, Xuwen; Shi, Xiaolai; Bai, Youcheng; Yu, Xiaoguo; Shi, Xuefa; Zhang, Weiyan; Zhang, Rongping

    2015-10-15

    Organic and inorganic sedimentary parameters in and off the Changjiang Estuary have been analyzed to reconstruct historical trends in eutrophication and hypoxia over the last century. The lipid biomarker concentrations in the Changjiang Estuary mud area (CEMA) indicated eutrophication accelerated after the 1970s. Meanwhile, Mo/Al indicated hypoxia has increased since 1960s. Eutrophication and hypoxia in the CEMA are primarily a result of the dramatically increased load of terrestrial nutrients from the Changjiang to the East China Sea. The lipid biomarker concentrations in the southwest Cheju Island mud area (SCIMA) showed primary production is controlled mainly by changes in regional climate and marine current. No significant hypoxia occurred in the SCIMA over the past century as indicated by Mo/Al. Therefore, geochemical indicators of eutrophication and hypoxia revealed different patterns between the CEMA and SCIMA, suggesting the role of river-derived nutrients in sustaining eutrophication and hypoxia in the CEMA since the 1960s. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Transnational linkages and sustainable transitions in emerging countries: Exploring the role of donor interventions in niche development

    DEFF Research Database (Denmark)

    Hansen, Ulrich Elmer; Nygaard, Ivan

    2013-01-01

    linkage in promoting the development of a palm oil biomass waste-to-energy niche in Malaysia. The paper contributes to the existing literature by a conceptual and empirical examination of this research question. With regard to its empirical findings the paper concludes: (i) that advice on energy policy...

  3. Linkages between Approaches to Learning, Perceived Stress and Expected and Actual Academic Outcomes among First-Semester Psychology Students

    Science.gov (United States)

    Öhrstedt, Maria; Lindfors, Petra

    2018-01-01

    Previous research indicates that higher educational students' perceptions of stress are in part related to the teaching and learning context, and influence academic outcomes. This study intends to deepen our understanding of these processes by examining the linkages between approaches to learning, perceived stress and expected and actual academic…

  4. The Instrumental Value of Interorganizational Relations: Antecedents and Consequences of Linkage Formation. Faculty Working Paper No. 454.

    Science.gov (United States)

    Whetten, David A.; Leung, Thomas K.

    As part of a larger investigation of the manpower training system, information on 67 manpower agencies located in several New York communities (excluding New York City) was collected during the summer of 1973. This study examines the determinants of agencies' attempts to establish interorganizational linkages that are instrumental to the…

  5. Combined Effects of Experimental Acidification and Eutrophication on Reef Sponge Bioerosion Rates

    Directory of Open Access Journals (Sweden)

    Alice E. Webb

    2017-09-01

    Full Text Available Health of tropical coral reefs depends largely on the balance between constructive (calcification and cementation and destructive forces (mechanical-chemical degradation. Gradual increase in dissolved CO2 and the resulting decrease in carbonate ion concentration (“ocean acidification” in ocean surface water may tip the balance toward net mass loss for many reefs. Enhanced nutrients and organic loading in surface waters (“eutrophication”, may increase the susceptibility of coral reef and near shore environments to ocean acidification. The impacts of these processes on coral calcification have been repeatedly reported, however the synergetic effects on bioerosion rates by sponges are poorly studied. Erosion by excavating sponges is achieved by a combination of chemical dissolution and mechanical chip removal. In this study, Cliona caribbaea, a photosymbiont-bearing excavating sponge widely distributed in Caribbean reef habitats, was exposed to a range of CO2 concentrations, as well as different eutrophication levels. Total bioerosion rates, estimated from changes in buoyant weights over 1 week, increased significantly with pCO2 but not with eutrophication. Observed chemical bioerosion rates were positively affected by both pCO2 and eutrophication but no interaction was revealed. Net photosynthetic activity was enhanced with rising pCO2 but not with increasing eutrophication levels. These results indicate that an increase in organic matter and nutrient renders sponge bioerosion less dependent on autotrophic products. At low and ambient pCO2, day-time chemical rates were ~50% higher than those observed at night-time. A switch was observed in bioerosion under higher pCO2 levels, with night-time chemical bioerosion rates becoming comparable or even higher than day-time rates. We suggest that the difference in rates between day and night at low and ambient pCO2 indicates that the benefit of acquired energy from photosynthetic activity surpasses

  6. On two methods to estimate production of Eichhornia crassipes in the eutrophic Pampulha reservoir (MG, Brazil).

    Science.gov (United States)

    Greco, M K B; de Freitas, J R

    2002-08-01

    This paper deals with variations in biomass and in the production of Eichhornia crassipes (water hyacinth) in a eutrophic tropical reservoir. Net production was assessed by both a traditional method and a demographic approach. The initial biomass ranges from 96 g DW.m-2 to a maximum of 2027 g DW.m-2. Net production estimates varied greatly according to which method was used to calculate them (traditional: 20.6 ton DW.hectare-1.year-1, demographic: 226.9 ton DW.year-1).

  7. On two methods to estimate production of Eichhornia crassipes in the eutrophic Pampulha reservoir (MG, Brazil

    Directory of Open Access Journals (Sweden)

    GRECO M. K. B.

    2002-01-01

    Full Text Available This paper deals with variations in biomass and in the production of Eichhornia crassipes (water hyacinth in a eutrophic tropical reservoir. Net production was assessed by both a traditional method and a demographic approach. The initial biomass ranges from 96 g DW.m-2 to a maximum of 2027 g DW.m-2. Net production estimates varied greatly according to which method was used to calculate them (traditional: 20.6 ton DW.hectare-1.year-1, demographic: 226.9 ton DW.year-1.

  8. In-situ nitrogen removal from the eutrophic water by microbial-plant integrated system.

    Science.gov (United States)

    Chang, Hui-qing; Yang, Xiao-e; Fang, Yun-ying; Pu, Pei-min; Li, Zheng-kui; Rengel, Zed

    2006-07-01

    This study was to assess the influence of interaction of combination of immobilized nitrogen cycling bacteria (INCB) with aquatic macrophytes on nitrogen removal from the eutrophic waterbody, and to get insight into different mechanisms involved in nitrogen removal. The aquatic macrophytes used include Eichhornia crassipes (summer-autumn floating macrophyte), Elodea nuttallii (winter-growing submerged macrophyte), and nitrogen cycling bacteria including ammonifying, nitrosating, nitrifying and denitrifying bacteria isolated from Taihu Lake. The immobilization carriers materials were made from hydrophilic monomers 2-hydroxyethyl acrylate (HEA) and hydrophobic 2-hydroxyethyl methylacrylate (HEMA). Two experiments were conducted to evaluate the roles of macrophytes combined with INCB on nitrogen removal from eutrophic water during different seasons. Eichhornia crassipes and Elodea nuttallii had different potentials in purification of eutrophic water. Floating macrophyte+bacteria (INCB) performed best in improving water quality (during the first experiment) and decreased total nitrogen (TN) by 70.2%, nitrite and ammonium by 92.2% and 50.9%, respectively, during the experimental period, when water transparency increased from 0.5 m to 1.8 m. When INCB was inoculated into the floating macrophyte system, the populations of nitrosating, nitrifying, and denitrifying bacteria increased by 1 to 2 orders of magnitude compared to the un-inoculated treatments, but ammonifying bacteria showed no obvious difference between different treatments. Lower values of chlorophyll a, COD(Mn), and pH were found in the microbial-plant integrated system, as compared to the control. Highest reduction in N was noted during the treatment with submerged macrophyte+INCB, being 26.1% for TN, 85.2% for nitrite, and 85.2% for ammonium at the end of 2nd experiment. And in the treatment, the populations of ammonifying, nitrosating, nitrifying, and denitrifying bacteria increased by 1 to 3 orders of

  9. In-situ nitrogen removal from the eutrophic water by microbial-plant integrated system*

    Science.gov (United States)

    Chang, Hui-qing; Yang, Xiao-e; Fang, Yun-ying; Pu, Pei-min; Li, Zheng-kui; Rengel, Zed

    2006-01-01

    Objective: This study was to assess the influence of interaction of combination of immobilized nitrogen cycling bacteria (INCB) with aquatic macrophytes on nitrogen removal from the eutrophic waterbody, and to get insight into different mechanisms involved in nitrogen removal. Methods: The aquatic macrophytes used include Eichhornia crassipes (summer-autumn floating macrophyte), Elodea nuttallii (winter-growing submerged macrophyte), and nitrogen cycling bacteria including ammonifying, nitrosating, nitrifying and denitrifying bacteria isolated from Taihu Lake. The immobilization carriers materials were made from hydrophilic monomers 2-hydroxyethyl acrylate (HEA) and hydrophobic 2-hydroxyethyl methylacrylate (HEMA). Two experiments were conducted to evaluate the roles of macrophytes combined with INCB on nitrogen removal from eutrophic water during different seasons. Results: Eichhornia crassipes and Elodea nuttallii had different potentials in purification of eutrophic water. Floating macrophyte+bacteria (INCB) performed best in improving water quality (during the first experiment) and decreased total nitrogen (TN) by 70.2%, nitrite and ammonium by 92.2% and 50.9%, respectively, during the experimental period, when water transparency increased from 0.5 m to 1.8 m. When INCB was inoculated into the floating macrophyte system, the populations of nitrosating, nitrifying, and denitrifying bacteria increased by 1 to 2 orders of magnitude compared to the un-inoculated treatments, but ammonifying bacteria showed no obvious difference between different treatments. Lower values of chlorophyll a, CODMn, and pH were found in the microbial-plant integrated system, as compared to the control. Highest reduction in N was noted during the treatment with submerged macrophyte+INCB, being 26.1% for TN, 85.2% for nitrite, and 85.2% for ammonium at the end of 2nd experiment. And in the treatment, the populations of ammonifying, nitrosating, nitrifying, and denitrifying bacteria

  10. Failure to find linkage between a functional polymorphism in the dopamine D4 receptor gene and schizophrenia

    Energy Technology Data Exchange (ETDEWEB)

    Shaikh, S.; Gill, M.; Collier, D.A. [Institute of Psychiatry, London (United Kingdom)] [and others

    1994-03-15

    We report the results of a linkage study in 24 families multiply affected with schizophrenia using a polymorphic DNA sequence encoding the third cytoplasmic loop of the dopamine D4 receptor. Two-point LOD score analyses with a range of single gene models ranging from near dominant to near recessive revealed no evidence for linkage. In addition, we examined the data by non-parametric sib-pair analysis and found no excess sharing of alleles between affected sib-pairs. We therefore conclude that mutations within the dopamine D4 receptor gene do not have a major aetiological role in schizophrenia in our collection of pedigrees. 20 refs., 2 tabs.

  11. Measures of trait mindfulness: Convergent validity, shared dimensionality, and linkages to the five-factor model.

    Science.gov (United States)

    Siegling, A B; Petrides, K V

    2014-01-01

    This study investigated, and partially aimed to replicate, important construct validity aspects and the homogeneity of trait mindfulness measures. Specifically, the study set out to examine whether a single dimension can explain the shared variance among these measures as well as the extent to which they converge with one another and in terms of their linkages to the five-factor model (FFM). Two samples completed all trait measures of the construct and one of them additionally completed a measure of the Big Five personality traits. Results showed that a single dimension explains the shared variance among measures based on the original, Eastern conceptualization of mindfulness, although not all of them seem to represent this construct comprehensively. Intercorrelations, dimensionality analysis, as well as linkages to the FFM indicated that the Eastern and Western conceptualizations, and their respective measures, reflect distinct constructs. However, the amount of variance overlap with the FFM was similar across the two conceptualizations.

  12. A three-dimensional water quality modeling approach for exploring the eutrophication responses to load reduction scenarios in Lake Yilong (China).

    Science.gov (United States)

    Zhao, Lei; Li, Yuzhao; Zou, Rui; He, Bin; Zhu, Xiang; Liu, Yong; Wang, Junsong; Zhu, Yongguan

    2013-06-01

    Lake Yilong in Southwestern China has been under serious eutrophication threat during the past decades; however, the lake water remained clear until sudden sharp increase in Chlorophyll a (Chl a) and turbidity in 2009 without apparent change in external loading levels. To investigate the causes as well as examining the underlying mechanism, a three-dimensional hydrodynamic and water quality model was developed, simulating the flow circulation, pollutant fate and transport, and the interactions between nutrients, phytoplankton and macrophytes. The calibrated and validated model was used to conduct three sets of scenarios for understanding the water quality responses to various load reduction intensities and ecological restoration measures. The results showed that (a) even if the nutrient loads is reduced by as much as 77%, the Chl a concentration decreased only by 50%; and (b) aquatic vegetation has strong interaction with phytoplankton, therefore requiring combined watershed and in-lake management for lake restoration. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Stock Market Linkages in Emerging Asia-Pacific Markets

    Directory of Open Access Journals (Sweden)

    Srinivasan Palamalai

    2013-11-01

    Full Text Available This study examines the stock market integration among major stock markets of emerging Asia-Pacific economies, viz. India, Malaysia, Hong Kong, Singapore, South Korea, Taiwan, Japan, China, and Indonesia. The Johansen and Juselius multivariate cointegration test, Granger causality/Block exogeneity Wald test based on the vector error correction model (VECM approach, and variance decomposition analysis were used to investigate the dynamic linkages between markets. Cointegration test confirmed a well-defined long-run equilibrium relationship among the major stock markets, implying that there exists a common force, such as arbitrage activity, which brings these stock markets together in the long run. The results of Granger causality/Block exogeneity Wald test based on VECM and variance decomposition analysis revealed the stock market interdependencies and dynamic interactions among the selected emerging Asia-Pacific economies. This result implies that investors can gain feasible benefits from international portfolio diversification in the short run. On the whole, the study results suggest that although long-term diversification benefits from exposure to these markets might be limited, short-run benefits might exist due to substantial transitory fluctuations.

  14. Assessment of Eutrophication in the Lower Yakima River Basin, Washington, 2004-07

    Science.gov (United States)

    Wise, Daniel R.; Zuroske, Marie L.; Carpenter, Kurt D.; Kiesling, Richard L.

    2009-01-01

    In response to concerns that excessive plant growth in the lower Yakima River in south-central Washington was degrading water quality and affecting recreational use, the U.S. Geological Survey and the South Yakima Conservation District conducted an assessment of eutrophication in the lower 116 miles of the river during the 2004-07 irrigation seasons (March - October). The lower Yakima River was divided into three distinct reaches based on geomorphology, habitat, aquatic plant and water-quality conditions. The Zillah reach extended from the upstream edge of the study area at river mile (RM) 116 to RM 72, and had abundant periphyton growth and sparse macrophyte growth, the lowest nutrient concentrations, and moderately severe summer dissolved oxygen and pH conditions in 2005. The Mabton reach extended from RM 72 to RM 47, and had sparse periphyton and macrophyte growth, the highest nutrient conditions, but the least severe summer dissolved oxygen and pH conditions in 2005. The Kiona reach extended from RM 47 to RM 4, and had abundant macrophyte and epiphytic algae growth, relatively high nutrient concentrations, and the most severe summer dissolved oxygen and pH conditions in 2005. Nutrient concentrations in the lower Yakima River were high enough at certain times and locations during the irrigation seasons during 2004-07 to support the abundant growth of periphytic algae and macrophytes. The metabolism associated with this aquatic plant growth caused large daily fluctuations in dissolved oxygen concentrations and pH levels that exceeded the Washington State water-quality standards for these parameters between July and September during all 4 years, but also during other months when streamflow was unusually low. The daily minimum dissolved oxygen concentration was strongly and negatively related to the preceding day's maximum water temperature - information that could prove useful if a dissolved oxygen predictive model is developed for the lower Yakima River

  15. Mapping organizational linkages in the agricultural innovation system of Azerbaijan

    NARCIS (Netherlands)

    Temel, T.

    2004-01-01

    This study describes the evolving context and organisational linkages in the agricultural innovation system of Azerbaijan and suggests ways to promote effective organisational ties for the development, distribution and use of new or improved information and knowledge related to agriculture.

  16. LINKAGES: An Individual-based Forest Ecosystem Biogeochemistry Model

    Data.gov (United States)

    National Aeronautics and Space Administration — This model product contains the source codes for version 1 of the individual-based forest ecosystem biogeochemistry model LINKAGES and two subsequent versions as...

  17. LINKAGES: An Individual-based Forest Ecosystem Biogeochemistry Model

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This model product contains the source codes for version 1 of the individual-based forest ecosystem biogeochemistry model LINKAGES and two subsequent...

  18. Review of the Linkages between Gender Equity and Climate ...

    African Journals Online (AJOL)

    Review of the Linkages between Gender Equity and Climate Change Issues in ... International Journal of Tropical Agriculture and Food Systems ... Consequently, traditional roles are reinforced, girls education suffers, and women's ability to ...

  19. Mapping multiple QTL using linkage disequilibrium and linkage analysis information and multitrait data

    Directory of Open Access Journals (Sweden)

    Goddard Mike E

    2004-05-01

    Full Text Available Abstract A multi-locus QTL mapping method is presented, which combines linkage and linkage disequilibrium (LD information and uses multitrait data. The method assumed a putative QTL at the midpoint of each marker bracket. Whether the putative QTL had an effect or not was sampled using Markov chain Monte Carlo (MCMC methods. The method was tested in dairy cattle data on chromosome 14 where the DGAT1 gene was known to be segregating. The DGAT1 gene was mapped to a region of 0.04 cM, and the effects of the gene were accurately estimated. The fitting of multiple QTL gave a much sharper indication of the QTL position than a single QTL model using multitrait data, probably because the multi-locus QTL mapping reduced the carry over effect of the large DGAT1 gene to adjacent putative QTL positions. This suggests that the method could detect secondary QTL that would, in single point analyses, remain hidden under the broad peak of the dominant QTL. However, no indications for a second QTL affecting dairy traits were found on chromosome 14.

  20. Suggestive linkage of familial mesial temporal lobe epilepsy to chromosome 3q26.

    Science.gov (United States)

    Fanciulli, Manuela; Di Bonaventura, Carlo; Egeo, Gabriella; Fattouch, Jinane; Dazzo, Emanuela; Radovic, Slobodanka; Spadotto, Alessandro; Giallonardo, Anna Teresa; Nobile, Carlo

    2014-02-01

    To describe the clinical findings in a family with a benign form of mesial temporal lobe epilepsy and to identify the causative genetic factors. All participants were personally interviewed and underwent neurologic examination. The affected subjects underwent EEG and most of them neuroradiological examinations (MRI). All family members were genotyped with the HumanCytoSNP-12 v1.0 beadchip and linkage analysis was performed with Merlin and Simwalk2 programs. Exome sequencing was performed on HiSeq2000, after exome capture with SureSelect 50 Mb kit v2.0. The family had 6 members with temporal lobe epilepsy. Age at seizure onset ranged from 8 to 13 years. Five patients had epigastric auras often associated to oro-alimentary automatic activity, 3 patients presented loss of contact, and 2 experienced secondary generalizations. Febrile seizures occurred in 2 family members, 1 of whom also had temporal lobe epilepsy. EEG showed focal slow waves and epileptic abnormalities on temporal regions in 1 patient and was normal in the other affected individuals. MRI was normal in all temporal lobe epilepsy patients. We performed single nucleotide polymorphism-array linkage analysis of the family and found suggestive evidence of linkage (LOD score=2.106) to a region on chromosome 3q26. Haplotype reconstruction supported the linkage data and showed that the majority of unaffected family members carried the haplotype at risk. Whole exome sequencing failed to identify pathogenic mutations in genes of the candidate region. Our data suggest the existence of a novel locus for benign familial mesial temporal lobe epilepsy on chromosome 3q26. Our failure to identify pathogenic mutations in genes of this region may be due to limitations of the exome sequencing technology. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. New international linkages shaping the U.S. food system

    OpenAIRE

    Goldberg, Ray A.

    1993-01-01

    Global linkages in the food system are mo-way streets reaching into new markets and transporting new inputs, new technologies, new business relationships, and new participants into the food system. These linkages help create both highly competitive and interdependent new global and U.S. food systems. The U.S. system is setting new standards of operating efficiency and environmentally sound production as it serves global consumer needs for food, feed, fuel, and pharmaceuticals.

  2. Prolinks: a database of protein functional linkages derived from coevolution

    Science.gov (United States)

    Bowers, Peter M; Pellegrini, Matteo; Thompson, Mike J; Fierro, Joe; Yeates, Todd O; Eisenberg, David

    2004-01-01

    The advent of whole-genome sequencing has led to methods that infer protein function and linkages. We have combined four such algorithms (phylogenetic profile, Rosetta Stone, gene neighbor and gene cluster) in a single database - Prolinks - that spans 83 organisms and includes 10 million high-confidence links. The Proteome Navigator tool allows users to browse predicted linkage networks interactively, providing accompanying annotation from public databases. The Prolinks database and the Proteome Navigator tool are available for use online at . PMID:15128449

  3. Commodities and Linkages: Industrialisation in Sub-Saharan Africa

    OpenAIRE

    Kaplinsky, Raphael; Morris, Adam; Kaplan, David

    2011-01-01

    In a complementary Discussion Paper (MMCP DP 12 2011) we set out the reasons why we believe that there is extensive scope for linkage development into and out of SSA’s commodities sectors. In this Discussion Paper, we present the findings of our detailed empirical enquiry into the determinants of the breadth and depth of linkages in eight SSA countries (Angola, Botswana, Gabon, Ghana, Nigeria, South Africa Tanzania, and Zambia) and six sectors (copper, diamonds, gold, oil and gas, mining serv...

  4. Increase in dimethylsulfide (DMS emissions due to eutrophication of coastal waters offsets their reduction due to ocean acidification.

    Directory of Open Access Journals (Sweden)

    Nathalie eGypens

    2014-04-01

    Full Text Available Available information from manipulative experiments suggested that the emission of dimethylsulfide (DMS would decrease in response to the accumulation of anthropogenic CO2 in the ocean (ocean acidification. However, in coastal environments, the carbonate chemistry of surface waters was also strongly modified by eutrophication and related changes in biological activity (increased primary production and change in phytoplankton dominance during the last 50 years. Here, we tested the hypothesis that DMS emissions in marine coastal environments also strongly responded to eutrophication in addition to ocean acidification at decadal timescales. We used the R-MIRO-BIOGAS model in the eutrophied Southern Bight of the North Sea characterized by intense blooms of Phaeocystis that are high producers of dimethylsulfoniopropionate (DMSP, the precursor of DMS. We showed that, for the period from 1951 to 2007, eutrophication actually led to an increase of DMS emissions much stronger than the response of DMS emissions to ocean acidification.

  5. Eutrophication of lakes cannot be controlled by reducing nitrogen input: Results of a 37-year whole-ecosystem experiment

    Science.gov (United States)

    Schindler, David W.; Hecky, R. E.; Findlay, D. L.; Stainton, M. P.; Parker, B. R.; Paterson, M. J.; Beaty, K. G.; Lyng, M.; Kasian, S. E. M.

    2008-01-01

    Lake 227, a small lake in the Precambrian Shield at the Experimental Lakes Area (ELA), has been fertilized for 37 years with constant annual inputs of phosphorus and decreasing inputs of nitrogen to test the theory that controlling nitrogen inputs can control eutrophication. For the final 16 years (1990–2005), the lake was fertilized with phosphorus alone. Reducing nitrogen inputs increasingly favored nitrogen-fixing cyanobacteria as a response by the phytoplankton community to extreme seasonal nitrogen limitation. Nitrogen fixation was sufficient to allow biomass to continue to be produced in proportion to phosphorus, and the lake remained highly eutrophic, despite showing indications of extreme nitrogen limitation seasonally. To reduce eutrophication, the focus of management must be on decreasing inputs of phosphorus. PMID:18667696

  6. Record linkage strategies: Part II. Portable software and deterministic matching.

    Science.gov (United States)

    Wajda, A; Roos, L L; Layefsky, M; Singleton, J A

    1991-08-01

    Software to perform record linkage should have several characteristics: (1) portability in being able to function with researchers' current arrangement of computer systems and languages, (2) flexibility in handling different linkage strategies, and (3) low cost in both computer time and researchers' efforts. A linkage package (LINKS) is described which satisfies these criteria; LINKS provides tools for both deterministic and probabilistic linkage as well as test modules for assessing data quality and structure. Because each linkage project is different, the modular nature of the software allows for better control of the programming process and development of unique strategies. Since the user provides the weights and decision rules, he may modify data between steps and/or develop extra steps to supplement the basic modules. In two information-rich linkage projects involving California AIDS data, LINKS identified mortality using deterministic approaches and permitted comparisons with other software and strategies. Flexible software and a deterministic approach would have eliminated the expensive key entry used to add full names and social security numbers as additional identifiers to one of the California data files.

  7. SNP Discovery and Linkage Map Construction in Cultivated Tomato

    Science.gov (United States)

    Shirasawa, Kenta; Isobe, Sachiko; Hirakawa, Hideki; Asamizu, Erika; Fukuoka, Hiroyuki; Just, Daniel; Rothan, Christophe; Sasamoto, Shigemi; Fujishiro, Tsunakazu; Kishida, Yoshie; Kohara, Mitsuyo; Tsuruoka, Hisano; Wada, Tsuyuko; Nakamura, Yasukazu; Sato, Shusei; Tabata, Satoshi

    2010-01-01

    Few intraspecific genetic linkage maps have been reported for cultivated tomato, mainly because genetic diversity within Solanum lycopersicum is much less than that between tomato species. Single nucleotide polymorphisms (SNPs), the most abundant source of genomic variation, are the most promising source of polymorphisms for the construction of linkage maps for closely related intraspecific lines. In this study, we developed SNP markers based on expressed sequence tags for the construction of intraspecific linkage maps in tomato. Out of the 5607 SNP positions detected through in silico analysis, 1536 were selected for high-throughput genotyping of two mapping populations derived from crosses between ‘Micro-Tom’ and either ‘Ailsa Craig’ or ‘M82’. A total of 1137 markers, including 793 out of the 1338 successfully genotyped SNPs, along with 344 simple sequence repeat and intronic polymorphism markers, were mapped onto two linkage maps, which covered 1467.8 and 1422.7 cM, respectively. The SNP markers developed were then screened against cultivated tomato lines in order to estimate the transferability of these SNPs to other breeding materials. The molecular markers and linkage maps represent a milestone in the genomics and genetics, and are the first step toward molecular breeding of cultivated tomato. Information on the DNA markers, linkage maps, and SNP genotypes for these tomato lines is available at http://www.kazusa.or.jp/tomato/. PMID:21044984

  8. Simulation-based inexact chance-constrained nonlinear programming for eutrophication management in the Xiangxi Bay of Three Gorges Reservoir.

    Science.gov (United States)

    Huang, Y L; Huang, G H; Liu, D F; Zhu, H; Sun, W

    2012-10-15

    Although integrated simulation and optimization approaches under stochastic uncertainty have been applied to eutrophication management problems, few studies are reported in eutrophication control planning where multiple formats of uncertainties and nonlinearities are addressed in forms of intervals and probabilistic distributions within an integrated framework. Since the impounding of Three Gorges Reservoir (TGR), China in 2003, the hydraulic conditions and aquatic environment of the Xiangxi Bay (XXB) have changed significantly. The resulting emergence of eutrophication and algal blooms leads to its deteriorated water quality. The XXB becomes an ideal case study area. Thus, a simulation-based inexact chance-constrained nonlinear programming (SICNP) model is developed and applied to eutrophication control planning in the XXB of the TGR under uncertainties. In the SICNP, the wastewater treatment costs for removing total phosphorus (TP) are set as the objective function; effluent discharge standards, stream water quality standards and eutrophication control standards are considered in the constraints; a steady-state simulation model for phosphorus transport and fate is embedded in the environmental standards constraints; the interval programming and chance-constrained approaches are integrated to provide interval decision variables but also the associated risk levels in violating the system constraints. The model results indicate that changes in the violating level (q) will result in different strategy distributions at spatial and temporal scales; the optimal value of cost objective is from [2.74, 13.41] million RMB to [2.25, 13.08] million RMB when q equals from 0.01 to 0.25; the required TP treatment efficiency for the Baisha plant is the most stringent, which is followed by the Xiakou Town and the Zhaojun Town, while the requirement for the Pingyikou cement plant is the least stringent. The model results are useful for making optimal policies on eutrophication

  9. Eutrophication in the Yunnan Plateau lakes: the influence of lake morphology, watershed land use, and socioeconomic factors.

    Science.gov (United States)

    Liu, Wenzhi; Li, Siyue; Bu, Hongmei; Zhang, Quanfa; Liu, Guihua

    2012-03-01

    Lakes play an important role in socioeconomic development and ecological balance in China, but their water quality has deteriorated considerably in recent decades. In this study, we investigated the spatial-temporal variations of eutrophication parameters (secchi depth, total nitrogen, total phosphorus, chemical oxygen demand, chlorophyll-a, trophic level index, and trophic state index) and their relationships with lake morphology, watershed land use, and socioeconomic factors in the Yunnan Plateau lakes. Results indicated that about 77.8% of lakes were eutrophic according to trophic state index. The plateau lakes showed spatial variations in water quality and could be classified into high-nutrient and low-nutrient groups. However, because watersheds were dominated by vegetation, all eutrophication parameters except chlorophyll-a showed no significant differences between the wet and dry seasons. Lake depth, water residence time, volume, and percentage of built-up land were significantly related to several eutrophication parameters. Agricultural land use and social-economic factors had no significant correlation with all eutrophication parameters. Stepwise regression analyses demonstrated that lake depth and water residence time accounted for 73.8% to 87.6% of the spatial variation of single water quality variables, respectively. Redundancy analyses indicated that lake morphology, watershed land use, and socioeconomic factors together explained 74.3% of the spatial variation in overall water quality. The results imply that water quality degradation in the plateau lakes may be mainly due to the domestic and industrial wastewaters. This study will improve our understanding of the determinants of lake water quality and help to design efficient strategies for controlling eutrophication in the plateau region.

  10. [Community Dynamics of Phytoplankton and Related Affecting Factors in a Eutrophicated Small Pond].

    Science.gov (United States)

    Yang, Wen; Zhu, Jin-yong; Zhang, Ke-xin; Wan, Li; Lu, Kai-hong

    2015-04-01

    The high-density sampling of eutrophic water can help to reveal the general rules of phytoplankton community succession and the relationship with environmental factors. The species and abundance of plankton and the physical-chemical factors were tracked for 30 weeks from March to October in a eutrophicated small pond. The relationships between the phytoplankton community dynamic change and the physical-chemical factors as well as the zooplankton in the water body community were studied by the multivariate statistical analysis with PRIMER. A total of 54 phytoplankton and 55 zooplankton species were identified, and the abundances of plankton varied from 0.28 x 10(8) - 6.11 x 10(8) cells x L(-1) for phytoplankton and 26-2.5 x 10(5) ind x L(-1) for zooplankton. The dominant species of phytoplankton were Cyanophyta and Chlorophyta, and an obvious succession process was showed with the seasonal change, which could be roughly divided into three stages: Chlorophyta-Cryptophyta type, Chlorophyta-Cyanophyta type and Cyanophyta type. BIO-ENV showed that pH, water temperature, transparency, total phosphorus and the abundances of Rotifera and Copepoda were the most critical influencing factors on the community dynamics of phytoplankton, and compared to zooplankton, the physical-chemical factors might have a greater influence.

  11. Investigation on extracellular polymeric substances from mucilaginous cyanobacterial blooms in eutrophic freshwater lakes.

    Science.gov (United States)

    Xu, Huacheng; Yu, Guanghui; Jiang, Helong

    2013-09-01

    Enhanced knowledge on extracellular polymeric substances (EPSs) of mucilaginous cyanobacterial blooms could improve our understanding of its ecological significance. This study for the first time investigated the extraction and fractionation of EPS matrix from cyanobacterial blooms in a eutrophic freshwater lake, and the changes in chemical compositions in EPS matrix during extraction were systematically investigated by two-dimensional correlation spectroscopy (2D-COS). The analyses demonstrated that organic matters were unevenly distributed among the EPS matrix, with most of organic matters being tightly bound to cyanobacterial cells. In addition, the soluble and loosely bound EPS fractions mainly consisted of proteins, while polysaccharides became the predominant compounds in the tightly bound EPS fraction. Heating extraction at 60°C for 30min led to a high EPS yield and low cell lysis when compared with other extraction methods. The 2D-COS results revealed a preferential release of OH in polysaccharides versus amide I in proteins in the initial heating; whereas further extension of heating resulted in EPS degradation, with degradation rates arranging in a decreased order from amide I, amide II, polysaccharides-like substances to polysaccharides. These results obtained would help enhance our insights into EPS characterization from cyanobacterial blooms in eutrophic lakes. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Water Age Responses to Weather Conditions in a Hyper-Eutrophic Channel Reservoir in Southern China

    Directory of Open Access Journals (Sweden)

    Wei Du

    2016-08-01

    Full Text Available Channel reservoirs have the characteristics of both rivers and lakes, in which hydrodynamic conditions and the factors affecting the eutrophication process are complex and highly affected by weather conditions. Water age at any location in the reservoir is used as an indicator for describing the spatial and temporal variations of water exchange and nutrient transport. The hyper-eutrophic Changtan Reservoir (CTR in Southern China was investigated. Three weather conditions including wet, normal, and dry years were considered for assessing the response of water age by using the coupled watershed model Soil Water Assessment Tool (SWAT and the three-dimensional hydrodynamic model Environmental Fluid Hydrodynamic Code (EFDC. The results showed that the water age in CTR varied tremendously under different weather conditions. The averaged water ages at the downstream of CTR were 3 d, 60 d, and 110 d, respectively in the three typical wet, normal, and dry years. The highest water ages at the main tributary were >70 d, >100 d, and >200 d, respectively. The spatial distribution of water ages in the tributaries and the reservoir were mainly affected by precipitation. This paper provides useful information on water exchange and transport pathways in channel reservoir, which will be helpful in understanding nutrient dynamics for controlling algal blooms.

  13. Effects of eutrophication, seasonality and macrofouling on the diversity of bacterial biofilms in equatorial coral reefs.

    Directory of Open Access Journals (Sweden)

    Yvonne Sawall

    Full Text Available Biofilms play an important role as a settlement cue for invertebrate larvae and significantly contribute to the nutrient turnover in aquatic ecosystems. Nevertheless, little is known about how biofilm community structure generally responds to environmental changes. This study aimed to identify patterns of bacterial dynamics in coral reef biofilms in response to associated macrofouling community structure, microhabitat (exposed vs. sheltered, seasonality, and eutrophication. Settlement tiles were deployed at four reefs along a cross-shelf eutrophication gradient and were exchanged every 4 months over 20 months. The fouling community composition on the tiles was recorded and the bacterial community structure was assessed with the community fingerprinting technique Automated Ribosomal Intergenic Spacer Analysis (ARISA. Bacterial operational taxonomic unit (OTU number was higher on exposed tiles, where the fouling community was homogenous and algae-dominated, than in sheltered habitats, which were occupied by a variety of filter feeders. Furthermore, OTU number was also highest in eutrophied near-shore reefs, while seasonal variations in community structure were most pronounced in the oligotrophic mid-shelf reef. In contrast, the macrofouling community structure did not change significantly with seasons. Changes in bacterial community patterns were mostly affected by microhabitat, seasonal and anthropogenically derived changes in nutrient availability, and to a lesser extent by changes in the macrofouling community structure. Path analysis revealed a complex interplay of various environmental and biological factors explaining the spatial and temporal variations in bacterial biofilm communities under natural conditions.

  14. Effects of snails, submerged plants and their coexistence on eutrophication in aquatic ecosystems

    Directory of Open Access Journals (Sweden)

    Mo Shuqing

    2017-01-01

    Full Text Available Eutrophication resulting from nutrient loading to freshwater habitats is a severe problem, leading to degradation of ecosystems, including deterioration of water quality, water clarity and loss of biodiversity. Measures enacted to restore degraded freshwater ecosystems often involve the reintroduction of submerged plants and aquatic animals with beneficial ecological functions. In a mesocosm experiment, three treatments (planting with Vallisneria natans, introduction of the snail Bellamya aeruginosa and a combined treatment with both plants and snails were compared with controls to evaluate their effects on trophic state. The total nitrogen (TN, total phosphorus (TP and chlorophyll a (Chl a concentrations of planktonic and benthic algal samples were determined every two weeks, along with light intensity at the sediment surface. The plant-only treatment significantly reduced the TN levels and planktonic and benthic algal biomass and increased the light intensity at the sediment surface. The snail-only treatment reduced the concentrations of TN and reduced planktonic and benthic algal biomass. The combined treatment decreased the concentrations of TN and TP, reduced planktonic algal biomass and increased the light intensity on the sediment surface. The results indicate that while submerged plants and snails can both improve water quality, the most pronounced effect in aquatic ecosystems is achieved by their presence in combination. A combined reintroduction approach may provide enhanced benefits in restoring the eutrophic ecosystems, following the reduction of external nutrient loading.

  15. Phosphate reclaim from simulated and real eutrophic water by magnetic biochar derived from water hyacinth.

    Science.gov (United States)

    Cai, Ru; Wang, Xin; Ji, Xionghui; Peng, Bo; Tan, Changyin; Huang, Xi

    2017-02-01

    In this study, the efficiency and mechanism of aqueous phosphate removal by magnetic biochar derived from water hyacinth (MW) were investigated. The MW pyrolyzed at 450 °C (MW450) exhibited the most prominent phosphate sorption capacity, which was estimated to be 5.07 mg g-1 based on Langmuir-Freundlich model. At an initial phosphorus (P) concentration of 1 mg l-1, >90% P removal was achieved over pH 3-9, but the efficiency decreased sharply at pH > 10. The presence of arsenate and carbonate could remarkably decrease P sorption, while the inhibition effects of antimonate, nitrate and sulfate were less significant. In further application of MW450 to reclaim P from eutrophic lake waters (0.71-0.94 mg l-1 total P), ∼96% P removals were attained in the batch studies and the effluent P concentrations in the column tests were reduced to hyacinth could provide a promising alternative for P removal from most eutrophic waters. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Effects of Eutrophication, Seasonality and Macrofouling on the Diversity of Bacterial Biofilms in Equatorial Coral Reefs

    Science.gov (United States)

    Sawall, Yvonne; Richter, Claudio; Ramette, Alban

    2012-01-01

    Biofilms play an important role as a settlement cue for invertebrate larvae and significantly contribute to the nutrient turnover in aquatic ecosystems. Nevertheless, little is known about how biofilm community structure generally responds to environmental changes. This study aimed to identify patterns of bacterial dynamics in coral reef biofilms in response to associated macrofouling community structure, microhabitat (exposed vs. sheltered), seasonality, and eutrophication. Settlement tiles were deployed at four reefs along a cross-shelf eutrophication gradient and were exchanged every 4 months over 20 months. The fouling community composition on the tiles was recorded and the bacterial community structure was assessed with the community fingerprinting technique Automated Ribosomal Intergenic Spacer Analysis (ARISA). Bacterial operational taxonomic unit (OTU) number was higher on exposed tiles, where the fouling community was homogenous and algae-dominated, than in sheltered habitats, which were occupied by a variety of filter feeders. Furthermore, OTU number was also highest in eutrophied near-shore reefs, while seasonal variations in community structure were most pronounced in the oligotrophic mid-shelf reef. In contrast, the macrofouling community structure did not change significantly with seasons. Changes in bacterial community patterns were mostly affected by microhabitat, seasonal and anthropogenically derived changes in nutrient availability, and to a lesser extent by changes in the macrofouling community structure. Path analysis revealed a complex interplay of various environmental and biological factors explaining the spatial and temporal variations in bacterial biofilm communities under natural conditions. PMID:22792198

  17. Heavy Metal Accumulation by Periphyton Is Related to Eutrophication in the Hai River Basin, Northern China

    Science.gov (United States)

    Tang, Wenzhong; Cui, Jingguo; Shan, Baoqing; Wang, Chao; Zhang, Wenqiang

    2014-01-01

    The Hai River Basin (HRB) is one of the most polluted river basins in China. The basin suffers from various types of pollutants including heavy metals and nutrients due to a high population density and rapid economic development in this area. We assessed the relationship between heavy metal accumulation by periphyton playing an important role in fluvial food webs and eutrophication in the HRB. The concentrations of the unicellular diatoms (type A), filamentous algae with diatoms (type B), and filamentous algae (type C) varied along the river, with type A dominating upstream, and types B then C increasing in concentration further downstream, and this was consistent with changes in the trophic status of the river. The mean heavy metal concentrations in the type A, B and C organisms were Cr: 18, 18 and 24 mg/kg, respectively, Ni: 9.2, 10 and 12 mg/kg, respectively, Cu: 8.4, 19 and 29 mg/kg, respectively, and Pb: 11, 9.8 and 7.1 mg/kg respectively. The bioconcentration factors showed that the abilities of the organisms to accumulate Cr, Ni and Pb decreased in the order type A, type B, then type C, but their abilities to accumulate Cu increased in that order. The Ni concentration was a good predictor of Cr, Cu and Pb accumulation by all three periphyton types. Our study shows that heavy metal accumulation by periphyton is associated with eutrophication in the rivers in the HRB. PMID:24482681

  18. Possible future effects of large-scale algae cultivation for biofuels on coastal eutrophication in Europe.

    Science.gov (United States)

    Blaas, Harry; Kroeze, Carolien

    2014-10-15

    Biodiesel is increasingly considered as an alternative for fossil diesel. Biodiesel can be produced from rapeseed, palm, sunflower, soybean and algae. In this study, the consequences of large-scale production of biodiesel from micro-algae for eutrophication in four large European seas are analysed. To this end, scenarios for the year 2050 are analysed, assuming that in the 27 countries of the European Union fossil diesel will be replaced by biodiesel from algae. Estimates are made for the required fertiliser inputs to algae parks, and how this may increase concentrations of nitrogen and phosphorus in coastal waters, potentially leading to eutrophication. The Global NEWS (Nutrient Export from WaterSheds) model has been used to estimate the transport of nitrogen and phosphorus to the European coastal waters. The results indicate that the amount of nitrogen and phosphorus in the coastal waters may increase considerably in the future as a result of large-scale production of algae for the production of biodiesel, even in scenarios assuming effective waste water treatment and recycling of waste water in algae production. To ensure sustainable production of biodiesel from micro-algae, it is important to develop cultivation systems with low nutrient losses to the environment. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Virioplankton dynamics are related to eutrophication levels in a tropical urbanized bay.

    Science.gov (United States)

    Cabral, Anderson S; Lessa, Mariana M; Junger, Pedro C; Thompson, Fabiano L; Paranhos, Rodolfo

    2017-01-01

    Virioplankton are an important and abundant biological component of marine and freshwater ecosystems. Often overlooked, aquatic viruses play an important role in biogeochemical cycles on a global scale, infecting both autotrophic and heterotrophic microbes. Viral diversity, abundance, and viral interactions at different trophic levels in aqueous environments are not well understood. Tropical ecosystems are less frequently studied than temperate ecosystems, but could provide new insights into how physical and chemical variability can shape or force microbial community changes. In this study, we found high viral abundance values in Guanabara Bay relative to other estuaries around the world. Viral abundance was positively correlated with bacterioplankton abundance and chlorophyll a concentrations. Moreover, prokaryotic and viral abundance were positively correlated with eutrophication, especially in surface waters. These results provide novel baseline data on the quantitative distribution of aquatic viruses in tropical estuaries. They also provide new information on a complex and dynamic relationship in which environmental factors influence the abundance of bacterial hosts and consequently their viruses. Guanabara Bay is characterized by spatial and seasonal variations, and the eutrophication process is the most important factor explaining the structuring of virioplankton abundance and distribution in this tropical urbanized bay.

  20. Will nutrient and light limitation prevent eutrophication in an anthropogenically-impacted coastal lagoon?

    Science.gov (United States)

    Domingues, Rita B.; Guerra, Cátia C.; Barbosa, Ana B.; Galvão, Helena M.

    2017-06-01

    The Ria Formosa coastal lagoon (southern Portugal) is a highly productive and valuable temperate ecosystem, subjected to strong anthropogenic impacts and highly vulnerable to climate change. The main goal of this work is to understand ecosystem susceptibility to eutrophication, by evaluating the isolated and combined effects of nutrient (N, P and Si) and light enrichments on phytoplankton growth and community composition during autumn, winter and spring. Microcosms of natural phytoplankton collected in the lagoon were subjected to different nutrient and light treatments and incubated in situ for 48 h. Nutrient consumption, and phytoplankton growth and community structure were evaluated using spectrophotometric methods, and inverted and epifluorescence microscopy. Diatoms were the only group potentially limited by nitrogen, and only during spring. Increased nutrient consumptions were observed for all nutrient additions in all seasons, not associated with phytoplankton growth, suggesting that luxury consumption was used to build up intracellular nutrient pools. Responses to light enrichment were inconsistent among phytoplankton groups, probably due to a high taxonomic seasonal variability. Positive responses to light enrichment were mostly observed during winter. Negative synergistic interactions between nutrients and light were also observed. We conclude that eutrophication is currently not a problem in the Ria Formosa coastal lagoon, but future nutrient enrichments may lead to accelerated growth of specific functional groups and species, if light is not limiting.