Differences in aggression, activity and boldness between native and introduced populations of an invasive crayfish

Science.gov (United States)

Pintor, L.M.; Sih, A.; Bauer, M.L.

2008-01-01

Aggressiveness, along with foraging voracity and boldness, are key behavioral mechanisms underlying the competitive displacement and invasion success of exotic species. However, do aggressiveness, voracity and boldness of the invader depend on the presence of an ecologically similar native competitor in the invaded community? We conducted four behavioral assays to compare aggression, foraging voracity, threat response and boldness to forage under predation risk of multiple populations of exotic signal crayfish Pacifastacus leniusculus across its native and invaded range with and without a native congener, the Shasta crayfish P. fortis. We predicted that signal crayfish from the invaded range and sympatric with a native congener (IRS) should be more aggressive to outcompete a close competitor than populations from the native range (NR) or invaded range and allopatric to a native congener (IRA). Furthermore, we predicted that IRS populations of signal crayfish should be more voracious, but less bold to forage under predation risk since native predators and prey likely possess appropriate behavioral responses to the invader. Contrary to our predictions, results indicated that IRA signal crayfish were more aggressive towards conspecifics and more voracious and active foragers, yet also bolder to forage under predation risk in comparison to NR and IRS populations, which did not differ in behavior. Higher aggression/voracity/ boldness was positively correlated with prey consumption rates, and hence potential impacts on prey. We suggest that the positive correlations between aggression/voracity/boldness are the result of an overall aggression syndrome. Results of stream surveys indicated that IRA streams have significantly lower prey biomass than in IRS streams, which may drive invading signal crayfish to be more aggressive/voracious/bold to acquire resources to establish a population. ?? 2008 The Authors.

Acute toxicity of chlorantraniliprole to non-target crayfish (Procambarus clarkii) associated with rice-crayfish cropping systems.

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Barbee, Gary C; McClain, W Ray; Lanka, Srinivas K; Stout, Michael J

2010-09-01

Chlorantraniliprole, a novel anthranilic diamide insecticide, was recently introduced into the United States where rice-crayfish crop rotations are practiced to control rice water weevil (Lissorhoptrus oryzophilus Kuschel) infestations. Chlorantraniliprole has high margins of mammalian safety and excellent insecticidal efficacy, but its toxicity to non-target crayfish is uncertain. In this study, the acute toxicity of chlorantraniliprole to the red swamp crayfish Procambarus clarkii Girard was determined using aquatic and feeding assays. The aquatic 96 h median lethal toxicity (LC(50)) data indicate that technical-grade chlorantraniliprole is highly toxic (US EPA category) to crayfish with an LC(50) of 951 microg L(-1) (95% CL = 741-1118 microg L(-1)). A no observed effect concentration (NOEC) of 480 microg L(-1) was recorded. Neither the 36 day chronic feeding study, where crayfish fed on chlorantraniliprole-treated rice seed in aquaria, nor the 144 h acute feeding test, where crayfish fed on rice seeds treated with chlorantraniliprole, produced mortality or abnormal behavior. Chlorantraniliprole is three orders of magnitude less acutely toxic to P. clarkii than lambda-cyhalothrin and etofenprox, two pyrethroid insecticides also used in rice, and is less likely to cause acute crayfish toxicity in rice pond ecosystems. Based on acute toxicity data, the use of chlorantraniliprole should be more compatible with rice-crayfish crop rotations than pyrethroids. (c) 2010 Society of Chemical Industry.

The Impacts of flow alterations to crayfishes in Southeastern Oklahoma, with an emphasis on the mena crayfish (orconectes menae)

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Brewer, Shannon K.; Dyer, Joseph J.

2016-01-01

Human activities can alter the environment to the point that it is unsuitable to the native species resulting in a loss of biodiversity. Ecologists understand the importance of biodiversity and the conservation of vulnerable species. Species that are narrowly endemic are considered to be particularly vulnerable because they often use specific habitats that are highly susceptible to human disturbance. The basic components of species conservation are 1) delineation of the spatial distribution of the species, 2) understanding how the species interacts with its environment, and 3) employing management strategies based on the ecology of the species. In this study, we investigated several crayfish species endemic to the Ouachita Mountains in Oklahoma and Arkansas. We established the spatial distributions (i.e., range) of the crayfish using Maximum Entropy species distribution modeling. We then investigated crayfish habitat use with quantitative sampling and a paired movement study. Finally, we evaluated the ability of crayfish to burrow under different environmental conditions in a controlled laboratory setting. Crayfish distribution at the landscape scale was largely driven by climate, geology and elevation. In general, the endemic crayfish in this study occurred above 300-m elevation where the geology was dominated by sandstone and shale, and rainfall totals were the highest compared to the rest of the study region. Our quantitative data indicated crayfish did not select for specific habitat types at the reach scale; however, crayfish appeared to continue to use shallow and dry habitat even as the streams dried. Movement by passive integrated transponder (PIT) tagged crayfish was highly variable but crayfish tended to burrow in response to drought rather than migrate to wet habitat. Controlled laboratory experiments revealed smaller substrate size (pebble) restricted crayfish burrowing more than larger substrates (cobble). We also found excess fine sediment restricted

Temporal variation in the prevalence of the crayfish plague pathogen, Aphanomyces astaci, in three Czech spiny-cheek crayfish populations

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Matasová K.

2011-06-01

Full Text Available North American crayfish species are natural hosts of the crayfish plague pathogen Aphanomyces astaci. The spiny-cheek crayfish Orconectes limosus, widespread in Central Europe, is the main reservoir of A. astaci in Czech Republic. We tested if there are temporal changes in the prevalence of infected individuals (i.e., the proportion of individuals in which the pathogen is detected in spiny-cheek crayfish populations. Crayfish from three populations shown previously to be infected to different extents (high, intermediate and low, were repeatedly sampled in different years (2004–2010 and seasons. The presence of A. astaci in the soft abdominal crayfish cuticle was tested by specific amplification of the pathogen DNA. There was no substantial temporal variation in pathogen prevalence in the highly and very lowly infected populations. However, a significant long-term as well as seasonal decrease was found in the intermediately infected population. This decline could be related to a decrease in population density over the studied years, and to crayfish seasonal moulting, respectively. A reliable estimate of pathogen prevalence in American crayfish populations thus requires repeated monitoring over years, preferably during the same season before the main period of crayfish moulting.

Comparative acute toxicity of neonicotinoid and pyrethroid insecticides to non-target crayfish (Procambarus clarkii) associated with rice-crayfish crop rotations.

Science.gov (United States)

Barbee, Gary C; Stout, Michael J

2009-11-01

Most insecticides used to control rice water weevil (Lissorhoptrus oryzophilus Kuscel) infestations are pyrethroids. However, pyrethroids are highly toxic to non-target crayfish associated with rice-crayfish crop rotations. One solution to the near-exclusive reliance on pyrethroids in a rice-crayfish pest management program is to incorporate neonicotinoid insecticides, which are insect specific and effective against weevils but not extremely toxic to crayfish. This study aimed to take the first step to assess neonicotinoids as alternatives to pyrethroids in rice-crayfish crop rotations by measuring the acute toxicities of three candidate neonicotinoid insecticides, clothianidin, dinotefuran and thiamethoxam, to juvenile Procambarus clarkii (Girard) crayfish and comparing them with the acute toxicities of two currently used pyrethroid insecticides, lambda-cyhalothrin and etofenprox. Neonicotinoid insecticides are at least 2-3 orders of magnitude less acutely toxic (96 h LC(50)) than pyrethroids to juvenile Procambarid crayfish: lambda-cyhalothrin (0.16 microg AI L(-1)) = etofenprox (0.29 microg AI L(-1)) > clothianidin (59 microg AI L(-1)) > thiamethoxam (967 microg AI L(-1)) > dinotefuran (2032 microg AI L(-1)). Neonicotinoid insecticides appear to be much less hazardous alternatives to pyrethroids in rice-crayfish crop rotations. Further field-level neonicotinoid acute and chronic toxicity testing with crayfish is needed. (c) 2009 Society of Chemical Industry.

Garden ponds as potential introduction pathway of ornamental crayfish

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Patoka J.

2014-01-01

Full Text Available The private stocking of ornamental crayfish in garden ponds was discussed in previous studies, but there is a lack of detailed analysis for better understanding of this introduction pathway. The Czech Republic is one of leading EU countries in trade with ornamental crayfish and private garden ponds are popular among people. The crayfish keepers in the country were interviewed by self-administered questionnaire to gather data about principal characteristics of the keepers and detailed information about crayfish breeding that are of interest for conservation managers. Besides of releasing crayfish into garden ponds, alarming illegal behavior such as releasing of juvenile crayfish into the wild, and capturing of indigenous crayfish from wild populations, were registered. Therefore focusing on public education to increase awareness of possible unwanted consequences of crayfish release and introduction of an obligation to inform customers about hazardousness of non-indigenous crayfish species for retailers and wholesalers is recommended.

REDUCING THE THREAT TO CONTROL INVASIVE SIGNAL CRAYFISH REDUCING: THE POTENTIAL USE OF PHEROMONES

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STEBBING P. D.

2003-04-01

Full Text Available The need for an effective method of controlling invasive species of crayfish is of utmost importance given the plight of Europe’s native crayfish species. Many techniques have been applied to the growing problem with little success. Pheromones have been used to control terrestrial insect pests for a number of years with many success stories. The concept of applying pheromone control methods to the aquatic environment is by no means new, but has not been previously developed. This paper discusses the preliminary results from field trials testing traps baited with Pacifastacus leniusculus pheromones, and the potential application of the pheromones in controlling P. leniusculus populations.

Phylogenetic species delimitation for crayfishes of the genus Pacifastacus.

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Larson, Eric R; Castelin, Magalie; Williams, Bronwyn W; Olden, Julian D; Abbott, Cathryn L

2016-01-01

Molecular genetic approaches are playing an increasing role in conservation science by identifying biodiversity that may not be evident by morphology-based taxonomy and systematics. So-called cryptic species are particularly prevalent in freshwater environments, where isolation of dispersal-limited species, such as crayfishes, within dendritic river networks often gives rise to high intra- and inter-specific genetic divergence. We apply here a multi-gene molecular approach to investigate relationships among extant species of the crayfish genus Pacifastacus, representing the first comprehensive phylogenetic study of this taxonomic group. Importantly, Pacifastacus includes both the widely invasive signal crayfish Pacifastacus leniusculus, as well as several species of conservation concern like the Shasta crayfish Pacifastacus fortis. Our analysis used 83 individuals sampled across the four extant Pacifastacus species (omitting the extinct Pacifastacus nigrescens), representing the known taxonomic diversity and geographic distributions within this genus as comprehensively as possible. We reconstructed phylogenetic trees from mitochondrial (16S, COI) and nuclear genes (GAPDH), both separately and using a combined or concatenated dataset, and performed several species delimitation analyses (PTP, ABGD, GMYC) on the COI phylogeny to propose Primary Species Hypotheses (PSHs) within the genus. All phylogenies recovered the genus Pacifastacus as monophyletic, within which we identified a range of six to 21 PSHs; more abundant PSHs delimitations from GMYC and ABGD were always nested within PSHs delimited by the more conservative PTP method. Pacifastacus leniusculus included the majority of PSHs and was not monophyletic relative to the other Pacifastacus species considered. Several of these highly distinct P. leniusculus PSHs likely require urgent conservation attention. Our results identify research needs and conservation priorities for Pacifastacus crayfishes in western

[A new method of therapy for branchiobdellosis in crayfish].

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Lohniský, K

1979-02-01

Crayfish (Astacus fluviatilis Fabricius, 1793) were treated three times with a bath of diluted ammonia water and proflavine for four and six minutes at a temperature of 18 degrees C to get rid of the ectoparasitic worms of Branchiobdella parasita Henle, 1835; the hatching ability of the Branchiobdella parasita eggs was stopped after the treatment. No lethal effect of the bath on the crayfish of 5 to 14 cm was observed, the lethal effect on the young crayfish borne on the uropods of the female crayfish cannot be eliminated: during the baths the young crayfish died (the death rate was approximately 6% of the average fertility of crayfish); the young crayfish may have been damaged during the treatment operations with the crayfish. The bath of diluted ammonia water and proflavine may be recommended for the treatment of branchiobdellosis in crayfish to be planted, or after several-hour storage of crayfish supplied to the market. One replication of the above cycle is sufficient according to the results obtained. The ammonia content in the ammonia water depends also on the duration of storage and on the storage temperature--it can drop during the storage. Therefore the ammonia water should be used as soon as possible after the despatchment from the place of production; the ammonia content should be determined by means of titration before preparing the bath, and according to this content the dilution ratio should be adjusted.

Habitat associations of three crayfish endemic to the Ouachita Mountain Ecoregion

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Dyer, Joseph J.; Brewer, Shannon K.

2018-01-01

Many crayfish are of conservation concern because of their use of unique habitats and often narrow ranges. In this study, we determined fine-scale habitat use by 3 crayfishes that are endemic to the Ouachita Mountains, in Oklahoma and Arkansas. We sampled Faxonius menae (Mena Crayfish), F. leptogonopodus (Little River Creek Crayfish), and Fallicambarus tenuis (Ouachita Mountain Crayfish) from wet and dry erosional channel units of 29 reaches within the Little River catchment. We compared channel-unit and microhabitat selection for each species. Crayfish of all species and life stages selected erosional channel units more often than depositional units, even though these sites were often dry. Accordingly, crayfish at all life stages typically selected the shallowest available microhabitats. Adult crayfish of all species and juvenile Little River Creek Crayfish selected patches of coarse substrate, and all crayfish tended to use the lowest amount of bedrock available. In general, we showed that these endemic crayfish used erosional channel units of streams, even when the channel units were dry. Conservation efforts that protect erosional channel units and mitigate actions that cause channel downcutting to bedrock would benefit these crayfish, particularly during harsh, summer drying periods.

Practical disinfection chemicals for fishing and crayfishing gear against crayfish plague transfer

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Jussila J.

2014-01-01

Full Text Available We tested four commercial disinfectants against crayfish plague (Aphanomyces astaci spores in both aquatic solutions and with material mimicking fishing and crayfishing gear, e.g. traps, ropes, mesh, etc. The tested disinfectants were Proxitane®5:14, Proxitane®12:20, Wofasteril®E400, Virkon®S and hydrogen peroxide. The effects of the chemicals were initially tested in liquid zoospore cultures and the effective concentrations were then further tested using clean and dirty model materials (PP sheet, nylon rope, cotton fabric contaminated with A. astaci spore solutions. The disinfectants effective against infective crayfish plague spores with both clean and dirty model materials were Proxinate®5:14 (effective concentration was 30 mg·L-1 of PAA and Virkon®S (3 g·L-1, while Proxinate®12:20 (10 mg·L-1 of PAA and Wofasteril®E400 (30 mg·L-1 of PAA worked only with clean model materials. Hydrogen peroxide was not effective in the tested concentrations and conditions. Based on the results, the disinfectants most suitable for the fishing and crayfishing gear disinfection would be Proxitane®5:14 and Virkon®S, with the condition that all the gear should be thoroughly cleaned of organic matter to ensure inactivation of A. astaci spores.

DISTRIBUTION OF CRAYFISH IN EUROPE AND SOME ADJOINING COUNTRIES

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HOLDICH D. M.

2002-07-01

Full Text Available The distribution of crayfish in Europe is examined using information from a variety of sources mainly for the last two decades. All European countries have at least one indigenous crayfish species (ICS, many with large stocks, and most countries in Western Europe have at least one non-indigenous crayfish species (NICS. Some species termed indigenous in certain countries may have been introduced in relatively recent times. However, the meaning of the term indigenous (native varies between countries. NICS continue to expand their ranges and present a continued threat to ICS through competition and transmission of diseases, notably crayfish plague. The current high level of interest in crayfish means that many countries are monitoring their crayfish situation and, where necessary, taking steps to renew stocks of threatened indigenous species, some of which are apparently on the verge of extinction. A more regular monitoring programme for European crayfish as a whole is needed if the demise of indigenous species is to be prevented.

Status and management of noble crayfish Astacus astacus in Estonia

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T. Paaver

2009-01-01

Full Text Available Noble crayfish Astacus astacus (L. is an indigenous and the only crayfish species in Estonia. It is potentially endangered by invasion of alien species, diseases and habitat deterioration but does not have legal protected status and is fished only for recreational purpose. Crayfish Working Group of Ministry of Environment and Department of Aquaculture of the Estonian University of Life Sciences have developed crayfish conservation and management plan. Since 1994 standardized test fishing with traps (which catch only crayfish over 7 cm TL has been carried out and database of these fishings shows, that crayfish is dwelling in more than 255 sites in the lakes, rivers, streams, artificial reservoirs. In 52% of monitored sites populations are weak, catch per trap night is below 1 specimen. Exceptionally rich is the stock on the island Saaremaa, where in 59% of populations catch per trap night is over 4 and can reach 50. Licensed recreational catch is allowed in regions, where monitoring data show good status of crayfish stock. It is not allowed to sell the crayfish caught on recreational license. Crayfishing season is limited with August, size limit in recreational fishery is 11 cm TL. There are 10 operating crayfish farms and 15 are under construction. The farms produce yearly around 1000 kg of commercial size crayfish for export to Finland. Over 200000 juveniles are produced for restocking yearly. Restocking projects e.g. restoration of populations, which have been lost because of plague have been successful. The main threat factor is crayfish plague. In 2006–2007 it destroyed the stock of crayfish farms of companies Veteko, Pähkla, Astacus and wild population of Põduste river on the island Saaremaa.

Impacts of drought and crayfish invasion on stream ecosystem structure and function

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Magoulick, Daniel D.

2014-01-01

Drought and seasonal drying can be important disturbance events in many small streams, leading to intermittent or isolated habitats. Many small streams contain crayfish populations that are often keystone or dominant species in these systems. I conducted an experiment in stream mesocosms to examine the effects of drought and potential ecological redundancy of a native and invasive crayfish species. I examined the effects of drought (drought or control) and crayfish presence (none, native crayfish Orconectes eupunctus or invasive crayfish Orconectes neglectus) on stream mesocosm structure and function (leaf breakdown, community metabolism, periphyton, sediment and chironomid densities) in a fully factorial design. Each mesocosm contained a deep and shallow section, and drought treatments had surface water present (5-cm depth) in deep sections where tiles and leaf packs were placed. Drought and crayfish presence did not interact for any response variable. Drought significantly reduced leaf breakdown, and crayfish presence significantly increased leaf breakdown. However, the native and invasive crayfish species did not differ significantly in their effects on leaf breakdown. Drought significantly reduced primary production and community respiration overall, whereas crayfish presence did not significantly affect primary production and community respiration. Neither drought nor crayfish presence significantly affected periphyton overall. However, drought significantly reduced autotrophic index (AI), and crayfish presence increased AI. Inorganic sediment and chironomid density were not affected by drought, but both were significantly reduced by crayfish presence. O. eupunctus reduced AI and sediment more than O. neglectus did. Neither drought nor crayfish species significantly affected crayfish growth or survival. Drought can have strong effects on ecosystem function, but weaker effects on benthic structure. Crayfish can have strong effects on ecosystem

Freshwater crayfish invasions in South Africa: past, present and ...

African Journals Online (AJOL)

Freshwater crayfish invasions have been studied around the world, but less so in Africa, a continent devoid of native freshwater crayfish. The present study reviews historical and current information on alien freshwater crayfish species introduced into South Africa and aims to indicate which areas are at risk from invasion.

Predatory functional response and prey choice identify predation differences between native/invasive and parasitised/unparasitised crayfish.

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Haddaway, Neal R; Wilcox, Ruth H; Heptonstall, Rachael E A; Griffiths, Hannah M; Mortimer, Robert J G; Christmas, Martin; Dunn, Alison M

2012-01-01

Invasive predators may change the structure of invaded communities through predation and competition with native species. In Europe, the invasive signal crayfish Pacifastacus leniusculus is excluding the native white clawed crayfish Austropotamobius pallipes. This study compared the predatory functional responses and prey choice of native and invasive crayfish and measured impacts of parasitism on the predatory strength of the native species. Invasive crayfish showed a higher (>10%) prey (Gammarus pulex) intake rate than (size matched) natives, reflecting a shorter (16%) prey handling time. The native crayfish also showed greater selection for crustacean prey over molluscs and bloodworm, whereas the invasive species was a more generalist predator. A. pallipes parasitised by the microsporidian parasite Thelohania contejeani showed a 30% reduction in prey intake. We suggest that this results from parasite-induced muscle damage, and this is supported by a reduced (38%) attack rate and increased (30%) prey handling time. Our results indicate that the per capita (i.e., functional response) difference between the species may contribute to success of the invader and extinction of the native species, as well as decreased biodiversity and biomass in invaded rivers. In addition, the reduced predatory strength of parasitized natives may impair their competitive abilities, facilitating exclusion by the invader.

MINIMISING LOSS OF CRAYFISH AND HABITATDURING WORKS ON WATERCOURSES

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PEAY S.

2003-04-01

Full Text Available Works in watercourses with white-clawed crayfish Austropotamobius pallipes cause temporary or permanent loss of habitat and crayfish. Past modifications can also leave waterbodies unfavourable for crayfish, but sometimes there is scope to improve them. Mitigation measures can reduce the impact and reinstate or even improve habitat. Various case studies show measures used during engineering works and some of the problems. Good planning and supervision are vital. The big issues at river and catchment scales (non-indigenous crayfish, disease, water quality and landuse may be higher priorities than provision of habitat at site or reach level; e.g. fencing in pastures improves riparian areas for crayfish and other species. If necessary, there are various options for natural and artificial refuges, but their success depends on flow characteristics, substrate and accessibility. Microhabitat can make the difference between success and failure.

Invasive crayfish threaten the development of submerged macrophytes in lake restoration.

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van der Wal, Jessica E M; Dorenbosch, Martijn; Immers, Anne K; Vidal Forteza, Constanza; Geurts, Jeroen J M; Peeters, Edwin T H M; Koese, Bram; Bakker, Elisabeth S

2013-01-01

Submerged macrophytes enhance water transparency and aquatic biodiversity in shallow water ecosystems. Therefore, the return of submerged macrophytes is the target of many lake restoration projects. However, at present, north-western European aquatic ecosystems are increasingly invaded by omnivorous exotic crayfish. We hypothesize that invasive crayfish pose a novel constraint on the regeneration of submerged macrophytes in restored lakes and may jeopardize restoration efforts. We experimentally investigated whether the invasive crayfish (Procambarus clarkii Girard) affects submerged macrophyte development in a Dutch peat lake where these crayfish are expanding rapidly. Seemingly favourable abiotic conditions for macrophyte growth existed in two 0.5 ha lake enclosures, which provided shelter and reduced turbidity, and in one lake enclosure iron was added to reduce internal nutrient loading, but macrophytes did not emerge. We transplanted three submerged macrophyte species in a full factorial exclosure experiment, where we separated the effect of crayfish from large vertebrates using different mesh sizes combined with a caging treatment stocked with crayfish only. The three transplanted macrophytes grew rapidly when protected from grazing in both lake enclosures, demonstrating that abiotic conditions for growth were suitable. Crayfish strongly reduced biomass and survival of all three macrophyte species while waterfowl and fish had no additive effects. Gut contents showed that crayfish were mostly carnivorous, but also consumed macrophytes. We show that P. clarkii strongly inhibit macrophyte development once favourable abiotic conditions for macrophyte growth are restored. Therefore, expansion of invasive crayfish poses a novel threat to the restoration of shallow water bodies in north-western Europe. Prevention of introduction and spread of crayfish is urgent, as management of invasive crayfish populations is very difficult.

A synthetic phylogeny of freshwater crayfish: insights for conservation

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Owen, Christopher L.; Bracken-Grissom, Heather; Stern, David; Crandall, Keith A.

2015-01-01

Phylogenetic systematics is heading for a renaissance where we shift from considering our phylogenetic estimates as a static image in a published paper and taxonomies as a hardcopy checklist to treating both the phylogenetic estimate and dynamic taxonomies as metadata for further analyses. The Open Tree of Life project (opentreeoflife.org) is developing synthesis tools for harnessing the power of phylogenetic inference and robust taxonomy to develop a synthetic tree of life. We capitalize on this approach to estimate a synthesis tree for the freshwater crayfish. The crayfish make an exceptional group to demonstrate the utility of the synthesis approach, as there recently have been a number of phylogenetic studies on the crayfishes along with a robust underlying taxonomic framework. Importantly, the crayfish have also been extensively assessed by an IUCN Red List team and therefore have accurate and up-to-date area and conservation status data available for analysis within a phylogenetic context. Here, we develop a synthesis phylogeny for the world's freshwater crayfish and examine the phylogenetic distribution of threat. We also estimate a molecular phylogeny based on all available GenBank crayfish sequences and use this tree to estimate divergence times and test for divergence rate variation. Finally, we conduct EDGE and HEDGE analyses and identify a number of species of freshwater crayfish of highest priority in conservation efforts. PMID:25561670

Electrophysiological Investigation of Different Methods of Anesthesia in Lobster and Crayfish

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Fregin, Torsten; Bickmeyer, Ulf

2016-01-01

Objectives In search for methods of anesthesia of crustaceans, an implanted electrode into lobster and crayfish CNS enabled us to monitor signal propagation in the nerve system of animals undergoing different protocols. Results Cooling (tap water 0°C, sea water -1,8°C) and anesthesia with MgCl2 (10%) were both discarded as anesthetic procedures because responses to external stimuli were still detectable under treatment. Contrarily, bubbling the aquarium water with CO2 can be considered a “partially successful” anesthesia, because signal propagation is inhibited but before that the animals show discomfort. The procedure of “electro-stunning” induces epileptic-form seizures in the crustacean CNS (lobster, crayfish), which overlay but do not mitigate the response to external stimuli. After several minutes the activity declines before the nervous system starts to recover. A feasible way to sacrifice lobsters is to slowly raise the water temperature (1°C min-1), as all electrical activities in the CNS cease at temperatures above ~30°C, whereas below this temperature the animals do not show signs of stress or escape behavior (e.g. tail flips) in the warming water. Conclusion CO2 is efficient to anaesthetize lobster and crayfish but due to low pH in water is stressful to the animals previous to anesthesia. Electrical stunning induces epileptiform seizures but paralyses the animals and leads to a reversible decline of nerve system activity after seizure. Electric stunning or slowly warming just before preparation may meet ethical expectations regarding anaesthesia and to sacrifice crustaceans. PMID:27642755

Modulation of legume defense signaling pathways by native and non-native pea aphid clones

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Carlos Sanchez-Arcos

2016-12-01

Full Text Available The pea aphid (Acyrthosiphon pisum is a complex of at least 15 genetically different host races that are native to specific legume plants, but can all develop on the universal host plant Vicia faba. Despite much research it is still unclear why pea aphid host races (biotypes are able to colonize their native hosts while other host races are not. All aphids penetrate the plant and salivate into plant cells when they test plant suitability. Thus plants might react differently to the various pea aphid host races. To find out whether legume species vary in their defense responses to different pea aphid host races, we measured the amounts of salicylic acid (SA, the jasmonic acid-isoleucine conjugate (JA-Ile, other jasmonate precursors and derivatives, and abscisic acid (ABA in four different species (Medicago sativa, Trifolium pratense, Pisum sativum, V. faba after infestation by native and non-native pea aphid clones of various host races. Additionally, we assessed the performance of the clones on the four plant species. On M. sativa and T. pratense, non-native clones that were barely able to survive or reproduce, triggered a strong SA and JA-Ile response, whereas infestation with native clones led to lower levels of both phytohormones. On P. sativum, non-native clones, which survived or reproduced to a certain extent, induced fluctuating SA and JA-Ile levels, whereas the native clone triggered only a weak SA and JA-Ile response. On the universal host V. faba all aphid clones triggered only low SA levels initially, but induced clone-specific patterns of SA and JA-Ile later on. The levels of the active JA-Ile conjugate and of the other JA-pathway metabolites measured showed in many cases similar patterns, suggesting that the reduction in JA signaling was due to an effect upstream of OPDA. ABA levels were downregulated in all aphid clone-plant combinations and were therefore probably not decisive factors for aphid-plant compatibility. Our results

It takes time to see the menu from the body: an experiment on stable isotope composition in freshwater crayfishes

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Jussila J.

2015-01-01

Full Text Available For many applications and ecological studies in which wild individuals are brought to laboratory it would be essential to know accurately how fast novel diet is reflected in composition of different tissues. To study the effects of two different diets on the stable isotope composition of freshwater crayfish muscle and hemolymph, we conducted a three month experiment on noble crayfish (Astacus astacus and signal crayfish (Pacifastacus leniusculus by feeding them sweet corn (Zea mays or Baltic herring (Clupea harengus membras as novel food. During the experiment, the crayfish were given 0.4 g of selected food daily and the amount consumed was recorded. The samples for the stable isotope analyses were taken at the commencement of the experiment (initial control and three times (hemolymph or twice (muscle tissue during the experiment. We found that stable isotope changes can be similarly, and rather slowly, detected from muscle tissue and hemolymph under studied conditions. Hemolymph sampling, being non-lethal, can be recommended as a practical sampling method. Our results confirm earlier reports according to which diet changes reflect to crayfish isotope ratios slowly implying that isotope ratios indicate long-term diet.

THE FRESHWATER CRAYFISH AUSTROPOTAMOBIUS PALLIPESIN SOUTH TYROL: HERITAGE SPECIES AND BIOINDICATOR

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FÜREDER L.

2003-04-01

Full Text Available Rapid decline of crayfish in European freshwaters and continuing threat necessitate integrated actions in conservation and management of native crayfish populations. Besides biological reasons (diseases, plague, the impact of toxic and harmful substances (fertilisers, herbicides or wastewater effluents, habitat alteration or fragmentation have been responsible for their decline in some regions. The same is true for the region of South Tyrol, where compared to previous investigations, only 10 of a former total of 15 crayfish locations in the water bodies could be affirmed. Although two new populations of the non-indigenous Astacus astacus were detected, the native Austropotamobius pallipes continues to decline. While many investigations have focused accurately on causal coherences for the decline of native populations, the properties of crayfish facilitate to reverse the situation. In a few examples, the potential of Austropotamobius pallipes, the native crayfish in South Tyrol, as “surrogate species” for effective biological conservation is discussed. Given the various adequate attributes of freshwater crayfish as surrogate species (including indicator species, umbrella species and flagship species qualities, they may help to advance not only the crayfish situation itself but also freshwater ecosystem properties in general.

Continental-wide distribution of crayfish species in Europe: update and maps

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Kouba A.

2014-01-01

Full Text Available Recently published astacological studies substantially improved available data on distribution of crayfish in various European regions. At the same time, spread of invasive species has been recorded, additional non-indigenous species became established in various countries, and losses of populations of native species due to crayfish plague and other negative factors were observed. We overview recent advances in this knowledge, and provide updated colour maps of the distribution of all crayfish species present in Europe. These maps are originally based on the data from the Atlas of Crayfish in Europe published in 2006 as a result of the CRAYNET project, and were further updated from more recently published reports, grey literature, and especially thanks to contributions and feedback of over 70 specialists from 32 countries. Separate maps are available for all indigenous crayfish species in Europe as well as for three most widespread non-indigenous crayfish species. Additionally, two maps give locations of known findings of crayfish species introduced to Europe after 1980. These newly established alien species have so far restricted distributions; however, the frequency of recent reports suggests that findings of such species resulting from releases of aquarium pets will further increase.

Visual shape recognition in crayfish as revealed by habituation.

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Cinzia Chiandetti

2017-08-01

Full Text Available To cope with the everyday challenges that they encounter in their evolutionary niche, crayfish are considered to rely mainly on chemical information or, alternatively, on tactile information, but not much on vision. Hence, research has focused on chemical communication, whereas crayfish visual abilities remain poorly understood and investigated. To fill in this gap, we tested whether crayfish (Procambarus clarkii can distinguish between two different visual shapes matched in terms of luminance. To this aim, we measured both the habituation response to a repeated presentation of a given shape, a downright Y, and the response recovery when a novel shape was presented. The novel shape could be either a Möbius or the same Y-shape but upright rotated. Our results demonstrate that, after habituation to the downright Y, crayfish showed a significantly higher response recovery to the Möbius as compared to the upright rotated Y. Hence, besides relying on chemo-haptic information, we found that crayfish can use sight alone to discriminate between different abstract geometrical shapes when macroscopically different. Failure to discriminate between the downright Y and its inversion or a generalization from the presence of a shape with three points creating a simple category, are both likely parsimonious explanations that should be investigated systematically in further studies. A future challenge will be understanding whether crayfish are capable of generalized shape recognition.

Parasites of crayfish ( P. clarki ) and lobsters ( Macrobrachium ...

African Journals Online (AJOL)

Studies on parasites of crayfish and lobsters as indicators of metal pollution in Great Kwa River, Nigeria was evaluated using appropriate instruments for determination of Physicochemical parameters and detection of metals. Formol ether centrifugation method was used for isolation of parasites. A total of 150 crayfish and ...

Double blow: Alien crayfish infected with invasive temnocephalan in South African waters

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Louis du Preez

2013-09-01

Full Text Available Trade in live, freshwater crayfish for ornamental markets, as well as for aquaculture, has grown rapidly and has become the major pathway for the introduction of non-indigenous crayfish species to several countries worldwide. Here we report on the first record of the Australian "redclaw" Cherax quadracarinatus in the natural waters of a game reserve in South Africa. To compound the situation, these redclaw crayfish were infected with a non-indigenous temnocephalan flatworm parasite. Both crayfish and temnocephalan were in full breeding condition, with young. Further spreading of this crayfish to the subtropical, water-rich, northern KwaZulu-Natal Province of South Africa and southern Mozambique is predicted. Not only might the crayfish compete with indigenous aquatic invertebrates but the non-host-specific temnocephalan might transfer to local decapods, such as freshwater crabs.

Expansion of the marbled crayfish in Slovakia: beginning of an invasion in the Danube catchment?

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Boris Lipták

2016-01-01

Full Text Available The marbled crayfish, Procambarus fallax f. virginalis, is a taxon widely available in the aquarium pet trade, which has been introduced to open waters in several European countries and in Madagascar. Recent studies confirmed this parthenogenetically reproducing crayfish as a high-risk invasive species, and vector of the crayfish plague pathogen, Aphanomyces astaci. It has been first discovered in Slovakia in 2010, but the status of the local population was not studied since then. Due to enlarged sampling area around the first report and one locality, where we presupposed the crayfish occurrence, we identified new marbled crayfish populations. Here, we report presence of three newly established marbled crayfish populations in Slovakia. Two populations are located critically close to the Váh River, a major tributary of the Danube River; one of them being directly connected to the Váh River via a side channel during occasional floods. The third established marbled crayfish population was found at the mouth of a thermal stream flowing into the Nitra River, a tributary of the Váh River. In this stream, crayfish coexist with other exotic fish and gastropod species of aquarium origin. We presume that the reported localities may serve as a source for further expansion of the marbled crayfish in the mid-part of the Danube catchment. Floods, active dispersal (including overland, passive dispersal by zoochory or anthropogenic translocations are among the major drivers facilitating the marbled crayfish colonization. We have not detected the crayfish plague pathogen in any of the studied populations. However, if spreading further, the marbled crayfish will encounter established populations of crayfish plague carriers in the Danube River, in which case they may acquire the pathogen by horizontal transmission and contribute to spread of this disease to indigenous European crayfish species.

UNDERSTANDING AND MANAGING BIODIVERSITY IN RELATION TO NATIVE CRAYFISH POPULATIONS IN EUROPE

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GHERARDI F.

2003-04-01

Full Text Available The loss or diminution of European crayfish populations because of both habitat deterioration and competition with alien crayfish – also responsible for the dissemination of the crayfish plague – would reduce the biodiversity at the species level. The topic “What is meant by biodiversity?” in the context of native freshwater crayfish in Europe was discussed during the Kilkenny CRAYNET meeting in order to make the point about the varied meanings of biodiversity from genes and individuals to population levels.

Different aspects of reproduction strategies in crayfish: A review

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Yazicioglu B.

2016-01-01

Full Text Available Study of the reproductive strategy of crayfish species is of great importance in the current astacological world. Crayfish are among the largest freshwater invertebrates, and as keystone species, they are able to regulate the structure of the benthic fauna in the freshwaters, demonstrating different ecological strategies and life spans ranging up to 20+ years. In order to bring together the various pieces of information related to this issue, this overview of published scientific reports was conducted. The majority of crayfish species studied show sexual dimorphism, with approximately equal numbers of males and females. However, over some decades numerous observations have been made for a few species that may have different modes of reproduction, such as hermaphroditism or intersex (e.g. Cherax quadricarinatus, Samastacus spinifrons, Parastacus virilastacus and Pacifastacus leniusculus and parthenogenesis (only Procambarus fallax f. virginalis. A recent study showed a new case of parthenogenesis as apomictic parthenogenesis (only Orconectes limosus. In addition, there are many investigations into the reproduction biology of crayfish, including using eyestalk ablation or androgenic gland ablation under various lab conditions and hybridization under natural conditions (e.g. Astacus astacus X Astacus leptodactylus, Orconectes rusticus X Orconectes propinquus. There are also some chemical factors which could possibly affect the reproduction system of crayfish in the wild.

The potential for using red claw crayfish and hybrid African catfish as ...

African Journals Online (AJOL)

The potential of red claw crayfish and hybrid African catfish (Clarias gariepinus and Clarias ngamensis) as predators for Schistosoma host snails was evaluated in 2014 by monitoring the consumption of snails by crayfish and catfish in experimental tanks over time under laboratory conditions. After 15 days, both crayfish and ...

Plant-soil interactions promote co-occurrence of three nonnative woody shrubs.

Science.gov (United States)

Kuebbing, Sara E; Classen, Aimée T; Call, Jaime J; Henning, Jeremiah A; Simberloff, Daniel

2015-08-01

Ecosystems containing multiple nonnative plant species are common, but mechanisms promoting their co-occurrence are understudied. Plant-soil interactions contribute to the dominance of singleton species in nonnative ranges because many nonnatives experience stronger positive feedbacks relative to co-occurring natives. Plant-soil interactions could impede other nonnatives if an individual nonnative benefits from its soil community to a greater extent than its neighboring nonnatives, as is seen with natives. However, plant-soil interactions could promote nonnative co-occurrence if a nonnative accumulates beneficial soil mutualists that also assist other nonnatives. Here, we use greenhouse and field experiments to ask whether plant-soil interactions (1) promote the codominance of two common nonnative shrubs (Ligustrum sinense and Lonicera maackii) and (2) facilitate the invasion of a less-common nonnative shrub (Rhamnus davurica) in deciduous forests of the southeastern United States. In the greenhouse, we found that two of the nonnatives, L. maackii and R. davurica, performed better in soils conditioned by nonnative shrubs compared to uninvaded forest soils, which. suggests that positive feedbacks among co-occurring nonnative shrubs can promote continued invasion of a site. In both greenhouse and field experiments, we found consistent signals that the codominance of the nonnatives L. sinense and L. maackii may be at least partially explained by the increased growth of L. sinense in L. maackii soils. Overall, significant effects of plant-soil interactions on shrub performance indicate that plant-soil interactions can potentially structure the co-occurrence patterns of these nonnatives.

Do culverts impact the movements of the endangered white-clawed crayfish?

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Louca V.

2014-01-01

Full Text Available Culverts can impact the migration and dispersal of aquatic animals and result in population fragmentation, increasing the risk of local extinction for endangered species such as the white-clawed crayfish Austropotamobius pallipes. This study used radio telemetry and passive integrated transponder (PIT telemetry to determine whether existing and experimental covered culverts affect the upstream and downstream movements of adult white-clawed crayfish. Daily crayfish movement rates did not differ significantly between an unlit 363-m long culvert and open stream channel sections. Crayfish moved into dark, covered sections volitionally. However, limited upstream movement occurred at sudden transitions of bed height or smooth-concrete box culvert sections with fast flow, suggesting partial barrier effects. In the 20-m long experimental in-stream culvert, also dark, but with natural stream bed, 70% of radio-tagged crayfish released downstream entered the culvert, as did 60% of those released upstream. Overall 35% passed through, with similar numbers in each direction. We conclude that dark culverts up to several hundred metres do not inhibit dispersal of white-clawed crayfish, provided stream slope, bed type and water velocity are amenable for movement and refuge. Care is required to ensure that culverts are bioengineered to ensure that average water velocity is sufficiently low and local hydraulic variation high, the bed and/or sidewalls contain refuge structures, and there are no cross-channel steps in bed level. Smooth-bedded box culverts are unlikely to be suitable for white-clawed crayfish.

Who is the boss? Individual recognition memory and social hierarchy formation in crayfish.

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Jiménez-Morales, Nayeli; Mendoza-Ángeles, Karina; Porras-Villalobos, Mercedes; Ibarra-Coronado, Elizabeth; Roldán-Roldán, Gabriel; Hernández-Falcón, Jesús

2018-01-01

Under laboratory conditions, crayfish establish hierarchical orders through agonistic encounters whose outcome defines the dominant one and one, or more, submissive animals. These agonistic encounters are ritualistic, based on threats, pushes, attacks, grabs, and avoidance behaviors that include retreats and escape responses. Agonistic behavior in a triad of unfamiliar, size-matched animals is intense on the first day of social interaction and the intensity fades on daily repetitions. The dominant animal keeps its status for long periods, and the submissive ones seem to remember 'who the boss is'. It has been assumed that animals remember and recognize their hierarchical status by urine signals, but the putative substance mediating this recognition has not been reported. The aim of this work was to characterize this hierarchical recognition memory. Triads of unfamiliar crayfish (male animals, size and weight-matched) were faced during standardized agonistic protocols for five consecutive days to analyze memory acquisition dynamics (Experiment 1). In Experiment 2, dominant crayfish were shifted among triads to disclose whether hierarchy depended upon individual recognition memory or recognition of status. The maintenance of the hierarchical structure without behavioral reinforcement was assessed by immobilizing the dominant animal during eleven daily agonistic encounters, and considering any shift in the dominance order (Experiment 3). Standard amnesic treatments (anisomycin, scopolamine or cold-anesthesia) were given to all members of the triads immediately after the first interaction session to prevent individual recognition memory consolidation and evaluate its effect on the hierarchical order (Experiment 4). Acquisition of hierarchical recognition occurs at the first agonistic encounter and agonistic behavior gradually diminishes in the following days; animals keep their hierarchical order despite the inability of the dominant crayfish to attack the submissive

FEEDING PREFERENCES OF THE INVASIVE CRAYFISH, PROCAMBARUS CLARKII

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Gherardi Francesca

2007-10-01

Full Text Available This laboratory study analyzes feeding preferences of a crayfish species with high invasive potentials, the red swamp crayfish Procambarus clarkii. We first conducted a series of multiple-choice tests among fresh plants (3 tests, one per each of three seasons, i.e. spring, summer, and autumn and animals (1 test in summer. In the first tests, crayfish were simultaneously offered fresh pieces of seven plants of different growth forms and taxonomic groups, selected on the basis of their availability in the habitat. In the second test, the offered animals were dead earthworms, rainbow trout fry, and toad tadpoles. Then, a binary choice test was run in autumn between the most preferred plant (Urtica sp. and earthworms. The percentages of organic C and N contents were measured for each food category using a gas-chromatography technique and the assimilation efficiency of both dry mass and organic content was assessed in a dedicated experiment. The results showed that P. clarkii is selective when offered fresh plants, consuming a relatively larger biomass of Urtica (in the three seasons examined, green algae (in spring, and Polygonum (in summer and autumn. Surprisingly, crayfish did not exhibit preference for any animal prey. Also, P. clarkii’s feeding decisions seemed not to be associated with either the availability of plants in the habitat or their occurrence in the gut contents of wild crayfish. Neither did their ingested biomass depend on the organic content or assimilation efficiency. Procambarus clarkii preferred Urtica sp. over earthworms, notwithstanding the higher nutritional value and assimilation efficiency of the latter. The above results might suggest that feeding preferences of the species often depend on factors other than nutritional value and digestibility. Future studies will analyze all the possible factors together in order to unravel the rules that govern feeding preferences in crayfish. In the case of invasive species, such

Distribution of native and exotic branchiobdellidans (Annelida: Clitellata on their respective crayfish hosts in northern Italy, with the first record of native Branchiobdella species on an exotic North American crayfish.

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Joy N. RAYBURN

1999-02-01

Full Text Available Branchiobdellidans were found on crayfish at the 18 sites examined in northern Italy. At 15 of the sites the native crayfish, Austropotamobius pallipes, was collected and all supported specimens of Branchiobdella italica. A few specimens of B. parasita were found at only two of these sites and no specimens of B. hexodonta were observed during the survey. The North American Louisiana red swamp crayfish, Procambarus (Scapulicambarus clarkii has been found in three additional sites around Carmagnola, south of Torino. The exotic Cambarincola mesochoreus was recovered from red crayfish at two sites. However, no specimens of C. mesochoreus were found at the third site, but specimens B. italica and B. parasita were identified. This is the first record of native Branchiobdella spp. on an exotic and wild crayfish in northern Italy.

Assessing the importance of food for improving noble crayfish culture conditions

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Rusch J.C.

2015-01-01

Full Text Available Captive breeding and crayfish culture are considered important measures in species protection activities. Thus, knowledge on optimal feeding of crayfish in captivity is needed in order to secure minimal mortality and prevent detrimental effects to health. To optimize conditions of crayfish prior to subsequent stocking, feeding trials were conducted with the aim of investigating the connection between food intake, food preference and temperature under near natural conditions. During a five-month period, noble crayfish were fed on fish, carrots, algae and chironomid-larvae according to a pre-defined rotation system, whereby the ambient water temperature ranged from 5 °C to 13 °C, following the natural temperature regime. The results of these feeding trials demonstrate a direct correlation between rising temperature and increasing food intake for water temperatures exceeding 8 °C. Food intake is further influenced by the variety of food items available at any one time. The results also confirm that Astacus astacus has a strong preference for fish and that alternation of food types has an impact on consumption. Our results prompt the following recommendations for optimized feeding conditions of crayfish in captivity prior to their release: (1 a balanced diet containing not only plant tissue but also a significant proportion of animal tissue and (2 the amount of available food must be adjusted according to the carapace length of the crayfish.

Status of the white-clawed crayfish, Austropotamobius pallipes (Lereboullet, 1858, in Spain : distribution and legislation

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ALONSO F.

2000-01-01

Full Text Available The white-clawed crayfish, Austropotamobius pallipes, is the only native species of freshwater crayfish in Spain. This species sustained a first-magnitude inland fishery up to the end of 1970's, when the crayfish plague struck the Spanish waters. It is detected an overall loss of distribution area of populations inhabiting the medium and lower reaches of the main river catchments, especially in Southern and Central Spain. The number of surviving populations can be estimated in ca. 700. Remaining native crayfish populations currently inhabit marginal areas. The populations are very fragmented, occupy short stretches, and are frequently isolated from the main river system. The current distribution is the result of a sum of different factors, i.e. crayfish plague, habitat alterations, extreme climatic drought, etc. The incidence and relative importance of each one varied during the last 15 years, with crayfish plague being a predominant negative factor in the seventies and eighties, and climatic drought in the nineties. The current trend of disappearance is a sufficient reason to consider the native crayfish as at risk of extinction. However neither the national legislation nor most of the regional government legislations have listed this species as endangered. An analysis of the legislation dealing with freshwater crayfish in Spain shows : (a an uneven and generally low level of protection given to the native species and (b a very complex fishing and commercialization regulations for crayfish that show significant changes from one region to another. This complex legislation, complemented with a general lack of data on crayfish populations, low levels of management and public involvement, and different strategies in regional governments regarding restocking programs with exotic species, makes a confusing situation. In order to decrease the general tendency of regression of A. pallipes a conservation program for this species needs to be implemented

Stream permanence influences crayfish occupancy and abundance in the Ozark Highlands, USA

Science.gov (United States)

Yarra, Allyson N.; Magoulick, Daniel D.

2018-01-01

Crayfish use of intermittent streams is especially important to understand in the face of global climate change. We examined the influence of stream permanence and local habitat on crayfish occupancy and species densities in the Ozark Highlands, USA. We sampled in June and July 2014 and 2015. We used a quantitative kick–seine method to sample crayfish presence and abundance at 20 stream sites with 32 surveys/site in the Upper White River drainage, and we measured associated local environmental variables each year. We modeled site occupancy and detection probabilities with the software PRESENCE, and we used multiple linear regressions to identify relationships between crayfish species densities and environmental variables. Occupancy of all crayfish species was related to stream permanence. Faxonius meeki was found exclusively in intermittent streams, whereas Faxonius neglectus and Faxonius luteushad higher occupancy and detection probability in permanent than in intermittent streams, and Faxonius williamsi was associated with intermittent streams. Estimates of detection probability ranged from 0.56 to 1, which is high relative to values found by other investigators. With the exception of F. williamsi, species densities were largely related to stream permanence rather than local habitat. Species densities did not differ by year, but total crayfish densities were significantly lower in 2015 than 2014. Increased precipitation and discharge in 2015 probably led to the lower crayfish densities observed during this year. Our study demonstrates that crayfish distribution and abundance is strongly influenced by stream permanence. Some species, including those of conservation concern (i.e., F. williamsi, F. meeki), appear dependent on intermittent streams, and conservation efforts should include consideration of intermittent streams as an important component of freshwater biodiversity.

MANAGEMENT STRATEGIES, YIELD AND POPULATION DEVELOPMENT OF THE NOBLE CRAYFISH ASTACUS ASTACUS IN LAKE STEINSFJORDEN

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SKURDAL J.

2002-07-01

Full Text Available Lake Steinsfjorden is the most important noble crayfish locality in Norway. The crayfish population has been monitored annually since 1979 including data on total trapping effort, yield and population composition before and after the catching season. The harvest has ranged from 0.7-4.7 kg.ha-1. The catch per trap night decreased prior to 1991 and the yield was reduced by some 50% over the years 1987-1992 as compared to 1979-1986. This was due to removal of small crayfish, high exploitation and the establishment of dense stands of Canadian pondweed (Elodea canadensis. Baited traps catch a large fraction of crayfish < 95 mm total length minimum size. These should according to the regulations immediately be released into the lake. However, it is apparent from the size composition that release of these small crayfish was rather incomplete. In 1983, trap mesh size was increased from 17.5 mm to 21 mm to reduce the fraction of undersized crayfish in the trap catches, yet no effects of this increased mesh size on crayfish size distribution were observed. The legal season has been reduced three times during the study period. In 1983, the closing date was changed from 31 December to 15 September. In 1989 the legal season was further reduced to two weeks and finally in 1995 to 10 days. This reduced total trap effort by 45%. The shorter season allow many crayfish to moult twice instead of once between seasons and the fraction of large crayfish has thus increased and so has the catch per trap night. Canadian pondweed has established dense annual stands and thus has made large parts of the shallow areas unsuitable for crayfish, causing an overall decrease in crayfish population size and production.

Investigation of plutonium concentration and distribution in burrowing crayfish from the White Oak Creek floodplain

International Nuclear Information System (INIS)

Delaney, M.S.; Dahlman, R.C.; Craig, R.B.

1979-01-01

The White Oak floodplain was contaminated with several radionuclides, including 239 Pu, during the Manhattan Project in 1944. Plutonium distribution in the soil is nonhomogeneous. An investigation was conducted to deterine Pu accumulation in a resident animal population. Crayfish were chosen because they complete their life-cycle within the contaminated environment, they directly contact contaminated muds, and they function in a food chain of significance to man. Two major conclusions of the research were that Pu concentrations in contaminated crayfish typically exceed those of control crayfish by two orders of magnitude and that if an incident were to occur in which a standard man ingested the soft tissues of ten crayfish from the floodplain, an insignificant whole body dose would accrue over the subsequent 50 years of life. The digestive tract of contaminated crayfish contained 21 to 33% of the Pu body burden, soft tissues contained 11 to 31% of the Pu body burden, and 48 to 62% of the Pu body burden of contaminated crayfish was associated with the carapace. Therefore, at a molt a large proportion of its accumulated Pu is deposited in the environment. A supplementary laboratory investigation using 237 Pu included a chronic Pu uptake study by uncontaminated crayfish. In these crayfish, from 64 to 82% of the 237 Pu was associated with the body tissues. Complementary data for 237 Pu associated with the carapace ranged from 18 to 37% of the distribution. An inventory of 239 Pu in crayfish at two sites on the floodplain was calculated by multiplying the estimated biomass of the crayfish by their average 239 Pu concentration. This evaluation of Pu associated with the crayfish population was compared to an inventory of 239 Pu in the soil in which they burrow and was found to be eight orders of magnitude less

Investigation of plutonium concentration and distribution in burrowing crayfish from the White Oak Creek floodplain

Energy Technology Data Exchange (ETDEWEB)

Delaney, M.S.; Dahlman, R.C.; Craig, R.B.

1979-01-01

The White Oak floodplain was contaminated with several radionuclides, including /sup 239/Pu, during the Manhattan Project in 1944. Plutonium distribution in the soil is nonhomogeneous. An investigation was conducted to deterine Pu accumulation in a resident animal population. Crayfish were chosen because they complete their life-cycle within the contaminated environment, they directly contact contaminated muds, and they function in a food chain of significance to man. Two major conclusions of the research were that Pu concentrations in contaminated crayfish typically exceed those of control crayfish by two orders of magnitude and that if an incident were to occur in which a standard man ingested the soft tissues of ten crayfish from the floodplain, an insignificant whole body dose would accrue over the subsequent 50 years of life. The digestive tract of contaminated crayfish contained 21 to 33% of the Pu body burden, soft tissues contained 11 to 31% of the Pu body burden, and 48 to 62% of the Pu body burden of contaminated crayfish was associated with the carapace. Therefore, at a molt a large proportion of its accumulated Pu is deposited in the environment. A supplementary laboratory investigation using /sup 237/Pu included a chronic Pu uptake study by uncontaminated crayfish. In these crayfish, from 64 to 82% of the /sup 237/Pu was associated with the body tissues. Complementary data for /sup 237/Pu associated with the carapace ranged from 18 to 37% of the distribution. An inventory of /sup 239/Pu in crayfish at two sites on the floodplain was calculated by multiplying the estimated biomass of the crayfish by their average /sup 239/Pu concentration. This evaluation of Pu associated with the crayfish population was compared to an inventory of /sup 239/Pu in the soil in which they burrow and was found to be eight orders of magnitude less.

A new ostracod (Entocytheridae, Notocytherinae) on New Guinea crayfish1)

NARCIS (Netherlands)

Hart, D.G.; Hart, C.W.

1970-01-01

In 1967 we examined the crayfish collections in the Rijksmuseum van Natuurlijke Historie, Leiden, to determine if the crayfishes collected in New Guinea in 1954 by Dr. L. B. Holthuis, Dr. L. D. Brongersma, and Dr. M. Boeseman (Boeseman, 1963) were hosts to commensal ostracods. Of the collections

EXPERIMENTAL EVIDENCE FOR HOMING IN THE RED SWAMP CRAYFISH, PROCAMBARUS CLARKII

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BARBARESI S.

2006-01-01

Full Text Available The red swamp crayfish, Procambarus clarkii, is an efficient burrower, but its burrow fidelity has been recently questioned. In this study, we aimed at investigating whether individuals of this species are capable to learn the position of a goal (a wet burrow hidden to their sight in experimental tanks and to make more efficient with time their oriented movement towards it. We also analyzed crayfish behavior after having closed one of the two accesses to the goal. Indeed, in successive trials we recorded the crayfish tendency to reduce the distance covered to reach the goal and the time taken, except when they were already familiar to the experimental setting. Memory of the spatial configuration lasted for 16 hours at least and crayfish learned and maintained individual trajectories. The interruption of their usual path always caused a drastic increase of distance and time that however decreased in the successive trials. This study provided also some information of the sensory channels used by P. clarkii to orient. This crayfish, which can be active also during daytime, seemed to adopt a combination of tactile and visual information, together with the possible use of cues (i.e. humidity cues emitted by the goal. Future studies should clarify the paradox of a crayfish species whose individuals, although being physiologically capable to home, seem not to return to the previously occupied burrows at the end of their foraging excursions, notwithstanding the time and energy expended to excavate them.

A review of the ever increasing threat to European crayfish from non-indigenous crayfish species

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D.M. Holdich

2009-01-01

Full Text Available Non-indigenous crayfish species (NICS in Europe now outnumber indigenous crayfish species (ICS 2:1, and it has been predicted that they may dominate completely in the next few decades unless something is done to protect them. Of the ten NICS introduced at least nine have become established in areas occupied by four of the five ICS. A decline in stocks of ICS has been recorded in many countries in the face of increasing populations of NICS. Most European countries retain at least one ICS but all are under threat from habitat loss, deteriorating water quality, overfishing, climate change, and most importantly from NICS and crayfish plague. The threat to ICS is so great in some countries that “ark”sanctuary sites are being established.The three most widely-spread NICS are the North American species: Pacifastacus leniusculus, Orconectes limosus and Procambarus clarkii. These can be considered as “Old NICS”, which were introduced before 1975, compared with the “New NICS”, which were introduced after 1980, such as the North American species: Orconectes immunis, Orconectes juvenilis, Orconectes virilis, Procambarus sp. and Procambarus acutus; and the Australian species: Cherax destructor and Cherax quadricarinatus, all of which have much narrower ranges in Europe. The North American species are potentially capable of acting as vectors of crayfish plague. Outbreaks of this disease occur regularly where there are high concentrations of vectors.In addition to the NICS currently established in the wild, a further threat exists through the aquarium trade, where many American and Australian species are available via the internet and in aquarist centres. Owners of such species may discard them into the freshwater environment when they grow too big as with some Cherax spp. and Orconectes spp., or multiply too frequently as with Procambarus sp. (a parthenogenetic species. A conceptual model is presented as a possible way forward for protecting the

STUDIES ON THE WHITE-CLAWED CRAYFISH (AUSTROPOTAMOBIUS PALLIPES ASSOCIATED WITH MUDDY HABITATS

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HOLDICH D. M.

2006-01-01

Full Text Available The white-clawed crayfish, Austropotamobius pallipes, is usually found associated with stony habitats containing obvious refuges in the form of gaps between and under rocks, macrophytes and marginal tree roots, particularly in streams and lakes with clear water and little marginal mud. If the banks are composed of suitable material, then they may also construct and live in burrows. However, the white-clawed crayfish is also found to be abundant in streams, rivers, canals and millraces with deep, anoxic mud and with very little aquatic vegetation. Foraging on the surface of mud may be the only way they can obtain sufficient food in the form of macroinvertebrates and decaying plant matter. Where do crayfish live in this restricted habitat? Dewatering such waterways for essential engineering works, such as desilting, bridge and weir repairs, bank reinforcements, and maintenance of outfalls can provide an excellent opportunity to study the available habitat and the crayfish populations, in addition good estimates of population size and age class distribution can be obtained, although, as with other methods, juveniles tend to be underrepresented. A number of case studies will be given to illustrate the fact that white-clawed crayfish are able to colonize muddy habitats in some numbers. The value of retaining trees with their roots hanging into waterways as a refuge for both crayfish and small fish is highlighted.

Distribution of native and exotic branchiobdellidans (Annelida: Clitellata) on their respective crayfish hosts in northern Italy, with the first record of native Branchiobdella species on an exotic North American crayfish.

OpenAIRE

Joy N. RAYBURN; Giovanni B. DELMASTRO; Stuart R. GELDER

1999-01-01

Branchiobdellidans were found on crayfish at the 18 sites examined in northern Italy. At 15 of the sites the native crayfish, Austropotamobius pallipes, was collected and all supported specimens of Branchiobdella italica. A few specimens of B. parasita were found at only two of these sites and no specimens of B. hexodonta were observed during the survey. The North American Louisiana red swamp crayfish, Procambarus (Scapulicambarus) clarkii has been found in three additional sites around Carma...

ZEBRA MUSSEL COLONIZATION OF RUSTY CRAYFISH IN GREEN BAY, LAKE MICHIGAN

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In August, 1995 six rusty crayfish colonized with zebra mussels were captured in small-meshed fyke-nets sets set apart as of a fish sampling effort at Peter's Marsh and Long-Tail Point Wetland in lower Green Bay. Mussels colonized virtually all areas of the crayfish bodies, but ...

Effects of mining-derived metals on riffle-dwelling crayfish in southwestern Missouri and southeastern Kansas, USA

Science.gov (United States)

Allert, Ann L.; DiStefano, Robert J.; Schmitt, Christopher J.; Fairchild, James F.; Brumbaugh, William G.

2012-01-01

Riffle-dwelling crayfish populations were sampled at 16 sites in 4 tributaries of the Spring River located within the Tri-State Mining District in southwest Missouri. Crayfish density, physical habitat quality, and water quality were examined at each site to assess the ecological effects of mining-derived metals on crayfish. Metals (lead, zinc, and cadmium) were analyzed in samples of surface water, sediment, detritus, and whole crayfish. Sites were classified a posteriori into reference, mining, and downstream sites primarily based on metal concentrations in the materials analyzed. Three species of crayfish (Orconectes neglectus neglectus, O. macrus, and O. virilis) were collected during the study; however, only O. n. neglectus was collected at all sites. Mean crayfish densities were significantly lower at mining sites than at reference sites. Mean concentrations of metals were significantly correlated among the materials analyzed and were significantly greater at mining and downstream sites than at reference sites. Principal component analyses showed a separation of sites due to an inverse relationship among crayfish density, metals concentrations, and physical habitat quality variables. Sediment probable-effects quotients and surface-water toxic unit scores were significantly correlated; both indicated risk of toxicity to aquatic biota at several sites. Metals concentrations in whole crayfish at several sites exceeded concentrations known to be toxic to carnivorous wildlife. Mining-derived metals have the potential to impair ecosystem function through decreased organic matter processing and nutrient cycling in streams due to decreased crayfish densities.

WHITE-CLAWED CRAYFISH IN MUDDY HABITATS: MONITORING THE POPULATION IN THE RIVER IVEL, BEDFORDSHIRE, UK

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PEAY S.

2006-01-01

Full Text Available White-clawed crayfish Austropotamobius pallipes are usually associated with stony substrates, tree roots, or refuges in submerged banks. The River Ivel has the last known population of white-clawed crayfish in Bedfordshire. Prior to 2005, much of the bed comprised uniform silt, plus leaf-litter. Stands of reedmace Typha latifolia and other emergent vegetation were localised in less shaded areas. Initial survey results suggested a population at low abundance. A low-cost monitoring strategy was started in 2001 and continued three times a year to 2005, using engineering bricks, which offer artificial refuges. Crayfish are counted when bricks are lifted periodically. De-silting of c. 430 m river was carried out in February 2005, to improve habitat and to maintain the flood capacity in the channel upstream of a mill weir. Additional bricks were deployed a few weeks in advance of de-silting, then bricks and crayfish were lifted prior to dredging and were returned the next day. Starting upstream, soft, wet mud was dredged out, placed on the bank and searched manually for crayfish. Banks, tree roots and shallow margins were left undisturbed. In all, 4,142 crayfish were found in dredgings from a 430 m length of the mid channel. Crayfish were strongly associated with emergent vegetation, but many were present below the surface of the silt. Crayfish released in the dredged channel immediately burrowed into the silt retained on the channel margins. Monitoring after dredging showed no change in abundance in the main area with in-bank refuges and lots of bricks, but there was an increase in occupancy of bricks in an area where most crayfish had been in emergent vegetation.

Circadian rhythm in melatonin release as a mechanism to reinforce the temporal organization of the circadian system in crayfish.

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Mendoza-Vargas, Leonor; Báez-Saldaña, Armida; Alvarado, Ramón; Fuentes-Pardo, Beatriz; Flores-Soto, Edgar; Solís-Chagoyán, Héctor

2017-06-01

Melatonin (MEL) is a conserved molecule with respect to its synthesis pathway and functions. In crayfish, MEL content in eyestalks (Ey) increases at night under the photoperiod, and this indoleamine synchronizes the circadian rhythm of electroretinogram amplitude, which is expressed by retinas and controlled by the cerebroid ganglion (CG). The aim of this study was to determine whether MEL content in eyestalks and CG or circulating MEL in hemolymph (He) follows a circadian rhythm under a free-running condition; in addition, it was tested whether MEL might directly influence the spontaneous electrical activity of the CG. Crayfish were maintained under constant darkness and temperature, a condition suitable for studying the intrinsic properties of circadian systems. MEL was quantified in samples obtained from He, Ey, and CG by means of an enzyme-linked immunosorbent assay, and the effect of exogenous MEL on CG spontaneous activity was evaluated by electrophysiological recording. Variation of MEL content in He, Ey, and CG followed a circadian rhythm that peaked at the same circadian time (CT). In addition, a single dose of MEL injected into the crayfish at different CTs reduced the level of spontaneous electrical activity in the CG. Results suggest that the circadian increase in MEL content directly affects the CG, reducing its spontaneous electrical activity, and that MEL might act as a periodical signal to reinforce the organization of the circadian system in crayfish.

Non-native Listeners’ Recognition of High-Variability Speech Using PRESTO

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Tamati, Terrin N.; Pisoni, David B.

2015-01-01

Background Natural variability in speech is a significant challenge to robust successful spoken word recognition. In everyday listening environments, listeners must quickly adapt and adjust to multiple sources of variability in both the signal and listening environments. High-variability speech may be particularly difficult to understand for non-native listeners, who have less experience with the second language (L2) phonological system and less detailed knowledge of sociolinguistic variation of the L2. Purpose The purpose of this study was to investigate the effects of high-variability sentences on non-native speech recognition and to explore the underlying sources of individual differences in speech recognition abilities of non-native listeners. Research Design Participants completed two sentence recognition tasks involving high-variability and low-variability sentences. They also completed a battery of behavioral tasks and self-report questionnaires designed to assess their indexical processing skills, vocabulary knowledge, and several core neurocognitive abilities. Study Sample Native speakers of Mandarin (n = 25) living in the United States recruited from the Indiana University community participated in the current study. A native comparison group consisted of scores obtained from native speakers of English (n = 21) in the Indiana University community taken from an earlier study. Data Collection and Analysis Speech recognition in high-variability listening conditions was assessed with a sentence recognition task using sentences from PRESTO (Perceptually Robust English Sentence Test Open-Set) mixed in 6-talker multitalker babble. Speech recognition in low-variability listening conditions was assessed using sentences from HINT (Hearing In Noise Test) mixed in 6-talker multitalker babble. Indexical processing skills were measured using a talker discrimination task, a gender discrimination task, and a forced-choice regional dialect categorization task. Vocabulary

Identification of exotic North American crayfish in Europe by DNA barcoding

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Filipová L.

2011-05-01

Full Text Available Several alien crayfish of North American origin have become established in Europe in recent decades, but their identification is often confusing. Our aim was to verify the taxonomic status of their European populations by DNA barcoding. We sequenced the cytochrome c oxidase subunit I (COI gene fragment of individuals representing all American crayfish known from European waters, and compared the results with reference sequences from North America. Our results confirm the morphological identification of Orconectes juvenilis from a population in eastern France, and of the marbled crayfish (Marmorkrebs, i.e., a parthenogenetic form of Procambarus fallax, from south-western Germany. Sequences of most individuals of presumed Procambarus acutus from the Netherlands were similar to American P. cf. acutus, but one was divergent, closer to a sequence of a reference individual of P. cf. zonangulus. However, divergences among three American P. cf. zonangulus samples were also high, comparable to interspecific variation within cambarid species complexes. The divergence between O. immunis from Europe and America also reached values corresponding to those observed among distinct Orconectes species. Genetic variation in the American range of these crayfish should therefore be further studied. Our study shows that DNA barcoding is useful for the rapid and accurate identification of exotic crayfish in Europe, and also provides insights into overall variation within these taxa.

Cadmium-binding proteins in midgut gland of freshwater crayfish Procambarus clarkii

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Del Ramo, J.; Pastor, A.; Torreblanca, A.; Medina, J.; Diza-Mayans, J.

1989-02-01

Metallothioneins, metal binding proteins, were originally isolated and characterized by Margoshes and Vallee. These proteins have a high affinity for various heavy metals, particularly cadmium and mercury and have extensively been studied in mammals. Metal binding proteins have been observed in a variety of marine invertebrates; however, there is very little information available on metal binding proteins in freshwater invertebrates, and particularly in freshwater crustaceans. Cadmium is an ubiquitous non essential element which possesses high toxicity to aquatic organisms. Cadmium binding proteins observed in invertebrates have similar characteristics to mammalian metallothioneins. In 1978, the American red crayfish appeared in Albufera Lake and the surrounding rice fields (Valencia, Spain). Albufera Lake and the surrounding rice fields waters are subjected to very heavy loads of sewage and toxic industrial residues (including heavy metals) from the many urban and wastewaters in this area. In previous reports the authors studied the toxicity and accumulation of cadmium on Procambarus clarkii of Albufera Lake. This crayfish shows a high resistance to cadmium and a great accumulation rate of this metal in several tissues, including midgut gland. Since Procambarus clarkii shows a high resistance to cadmium, the presence of cadmium binding proteins (Cd-BP) in midgut gland of these crayfish would be expected. This report describes results on the characterization of Cd-BPs obtained from cadmium exposed crayfish Procambarus clarkii, demonstrating their presence in this freshwater crayfish.

CRAYFISH PREDATION EXPERIMENTS ON THE INTRODUCED ZEBRA MUSSEL, DREISSENA POLYMORPHA, IN IRELAND, AND THEIR POTENTIAL FOR BIOCONTROL.

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REYNOLDS J. D.

2001-04-01

Full Text Available The zebra mussel Dreissena polymorpha, native to the Aralo-Caspian region, has spread across Europe in the last 180 years. Although it reached England in 1820, it only arrived in Ireland in around 1995, probably attached to the hull of pleasure boats, and since then has spread through the lowland Shannon and Erne systems, which are linked by canal. While White-clawed crayfish Austropotamobius pallipes (Lereboullet occur in these systems, Dreissena has not yet colonized sites with large crayfish populations. In laboratory experiments crayfish of both sexes ranging in size from 32-48 mm carapace length (CL were offered zebra mussels in 7 size classes spanning a range from 3-17 mm total length. Crayfish fed most on small mussels, although there was some correlation between size of crayfish and largest mussels attacked. When eaten mussels were not replaced, crayfish shifted to larger sizes. In the presence of alternative prey, experienced crayfish ate mussels and alternative foods in similar amounts while those who had never encountered zebra mussels nearly always chose the alternative foods first. The possibility of crayfish exerting significant controlling impacts on expanding mussel populations is discussed.

Mitochondrial cytochrome oxidase I gene analysis indicates a restricted genetic background in Finnish noble crayfish (Astacus astacus stocks

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Makkonen J.

2015-01-01

Full Text Available The IUCN Red List indexes the noble crayfish (Astacus astacus as vulnerable, with a declining population trend. The main threats to the species are the crayfish plague caused by the oomycete Aphanomyces astaci and the introduced North American crayfish that act as the carriers of this disease. In Finland, the noble crayfish is considered as a native species, which original distribution area covers the southern part of the country, but the species distribution has been dispersed to cover almost the whole country. The aim of this study was to survey the genetic diversity among the Finnish noble crayfish populations. The mitochondrial cytochrome oxidase I (COI-gene was sequenced from 742 individuals representing 59 populations from Finland and Estonia. As a result, only a single haplotype was found. Based on these results, the genetic diversity of noble crayfish in its Northern distribution range is remarkably low. The observed lack of variation can result from several mechanisms including small size of the founder population and the intense spreading of the species by manmade stockings. The restricted diversity can also be caused by eradication of the original populations due to crayfish plague epidemics and spreading of the invasive crayfish species carrying the crayfish plague. It is also possible that all contemporary Finnish noble crayfish populations originate from stockings with no variation in respect to COI-gene.

REVIEW OF THE NATIONAL RESTOCKING PROGRAMME “ACTIVE PROTECTION OF NATIVE CRAYFISH IN POLAND” 1999-2001

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ŠMIETANA P.

2004-01-01

Full Text Available After the first spread of crayfish plague (aphanomycosis at the end of the nineteenth century, the formerly abundant populations of native crayfish in Poland declined drastically. Analysis of historical data on the occurrence and distribution of crayfish in Poland led to the conclusion that without human intervention the native crayfish species would be at high risk of being made extinct. The largest programme concerning crayfish monitoring and restocking in Poland was “Active protection of native crayfish in Poland” conducted by the Inland Fisheries Institute, the Department of Ecology, University of Szczecin, the Department of Zoology, Warsaw Agricultural University and the University of Warmia and Mazury that was funded by the EkoFundusz Foundation and Inland Fisheries Institute in 1999-2001. One of the main objectives and results of this programme was the determination of indigenous crayfish distribution in Poland (mainly Astacus astacus and Astacus leptodactylus and the restocking of suitable habitats with indigenous crayfish. The densest populations (> 2 500 adult individuals per hectare were used as a source of restocking material. Restocking was performed in 54 water bodies using a total of 45 200 individuals of A. astacus and 9 800 of A. leptodactylus. Between 2001-2002, the success of the restocking programme was monitored. According to the results obtained so far, the restocking exercise has been successful in at least 60.8% of the cases.

Are Chinese consumers at risk due to exposure to metals in crayfish? A bioaccessibility-adjusted probabilistic risk assessment.

Science.gov (United States)

Peng, Qian; Nunes, Luís M; Greenfield, Ben K; Dang, Fei; Zhong, Huan

2016-03-01

Freshwater crayfish, the world's third largest crustacean species, has been reported to accumulate high levels of metals, while the current knowledge of potential risk associated with crayfish consumption lags behind that of finfish. We provide the first estimate of human health risk associated with crayfish (Procambarus clarkii) consumption in China, the world's largest producer and consumer of crayfish. We performed Monte Carlo Simulation on a standard risk model parameterized with local data on metal concentrations, bioaccessibility (φ), crayfish consumption rate, and consumer body mass. Bioaccessibility of metals in crayfish was found to be variable (68-95%) and metal-specific, suggesting a potential influence of metal bioaccessibility on effective metal intake. However, sensitivity analysis suggested risk of metals via crayfish consumption was predominantly explained by consumption rate (explaining >92% of total risk estimate variability), rather than metals concentration, bioaccessibility, or body mass. Mean metal concentrations (As, Cd, Cu, Ni, Pb, Se and Zn) in surveyed crayfish samples from 12 provinces in China conformed to national safety standards. However, risk calculation of φ-modified hazard quotient (HQ) and hazard index (HI) suggested that crayfish metals may pose a health risk for very high rate consumers, with a HI of over 24 for the highest rate consumers. Additionally, the φ-modified increased lifetime risk (ILTR) for carcinogenic effects due to the presence of As was above the acceptable level (10(-5)) for both the median (ILTR=2.5×10(-5)) and 90th percentile (ILTR=1.8×10(-4)), highlighting the relatively high risk of As in crayfish. Our results suggest a need to consider crayfish when assessing human dietary exposure to metals and associated health risks, especially for high crayfish-consuming populations, such as in China, USA and Sweden. Copyright © 2016 Elsevier Ltd. All rights reserved.

Partition of ruthenium-106 between the fresh water environment and crayfish

International Nuclear Information System (INIS)

Berg, G.G.; Ginsberg, E.

1976-01-01

Crayfish of two species, Orconectes obscurus and Cambarus robustus, were identified in West Valley, New York, in streams contaminated with radioactive wastes. 106 Ru accounted for over 90% of the gamma radioactivity in specimens collected in 1972, and had higher concentrations in the crayfish than in fish from that site. Crayfish are suggested as indicator organisms for 106 Ru. In subsequent aquarium experiments, crayfish exposed to water labeled with inorganic complexes of 106 Ru concentrated the dissolved ruthenium an average of 9 x and accumulated 50% of the equilibrium body burden in approximately 10 hr, with the bulk of the isotope bound at the surface of the exoskeleton. If food was also exposed to the labeled water, uptake was faster and high concentrations were found in the digestive gland, which showed concentration factors in excess of 25 x. Releases were slower and bimodal, with approximately 10% of body burden remaining after 1 or 2 months in repeated changes of water. Data describe the partition of 106 Ru to colloidal aggregates and organically-bound sediments, and its availability for bioconcentration. (author)

Accumulation of Heavy Metals in Crayfish and Fish from Selected Czech Reservoirs

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Iryna Kuklina

2014-01-01

Full Text Available To evaluate the accumulation of aluminium, cadmium, chromium, copper, lead, mercury, nickel, and zinc in crayfish and fish organ tissues, specimens from three drinking water reservoirs (Boskovice, Landštejn, and Nová Říše and one contaminated site (Darkovské moře in the Czech Republic were examined. Crayfish hepatopancreas was confirmed to be the primary accumulating site for the majority of metals (Cu > Zn > Ni > Cd > Cr, while Hg and Cr were concentrated in abdominal muscle, and Al and Pb were concentrated in gill. Metals found in Nová Říše specimens included Cu > Zn > Ni and those found in Boskovice included Zn > Hg > Cr. Cd concentrations were observed only in Landštejn specimens, while contaminated Darkovské moře specimens showed the highest levels of accumulation (Cu > Al > Zn > Pb. The majority of evaluated metals were found in higher concentrations in crayfish: Cu > Al > Zn > Ni > Cr > Cd > Pb, with Hg being the only metal accumulating higher in fish. Due to accumulation similarities of Al in crayfish and fish gill, differences of Hg in muscle, and features noted for the remaining metals in examined tissues, biomonitoring should incorporate both crayfish and fish to produce more relevant water quality surveys.

KEYNOTE PRESENTATION AND ROUNDTABLE SESSION 4. CRAYFISH PATHOLOGY IN EUROPE:PAST, PRESENT AND A PROGRAMME FOR THE FUTURE

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EDGERTON B. F.

2004-01-01

Full Text Available The devastating affects of disease on European freshwater crayfish are well known as epizootics in wild populations have occurred throughout much of Europe since the mid XVIIIe s. After protracted and rigorous debate, the cause of the disease named crayfish plague was proved to be the fungus Aphanomyces astaci in 1934. In the last 70 years, much of the research conducted in the field of crayfish pathology has concentrated on fungi, especially improving diagnostic techniques for A. astaci. Similarly, diagnostic responses to epizootics in European crayfish have concentrated almost entirely on fungal isolation and/or identification. On the other hand, viruses have proved to be the most important pathogens in the growing global crustacean aquaculture and fishery industries. Rickettsia-like organisms (RLO are also important. Critically, diagnostic techniques necessary to detect the full range of potential pathogens of crayfish are rarely utilized in the field of crayfish pathology in Europe. Histopathological analysis, required for the diagnosis of infections by viruses and RLOs, is absent from most European studies. Epizootics unrelated to A. astaci in European crayfish and epizootics in introduced American crayfish species highlight the inadequate current state of knowledge in the field. Presently, the field is ill-equipped to determine the cause(s of these epizootics. Moreover, crayfish conservation strategies may be undermined and even detrimental to the longterm goals; eg., stocking programs may spread undetected pathogens. Therefore, critical limitations in the field of crayfish pathology have major repercussions in management of freshwater crayfish. Guiding principles and a concept for a trans-European Community research and education program were developed to address this serious issue and are presented herein.

Toxicological studies of cadmium and zinc on the crayfish Orconectes virilis

International Nuclear Information System (INIS)

Mirenda, R.J.

1985-01-01

The acute toxicities of cadmium and of zinc to the crayfish Oronectes virilis were determined. Adult, intermolt crayfish were exposed to a series of concentrations of either cadmium or zinc for a two week period. Cadmium was found to be a cumulative poison to the crayfish; LC50 values decreased from 6.1 mg Cd/I for 96 hours to 0.7 mg Cd/I for two weeks. An incipient LC50 was also estimated to be 0.0604 mg Cd/I. Zinc was found to have a relatively low toxicity to O. virilis under the present exposure conditions. Whole animal and tissue analyses for cadmium or zinc were performed on the crayfish used in the acute toxicity tests. Whole animals concentrations both for cadmium and for zinc exhibited a linear relationship to exposure concentrations (r = 0.85 and 0.87, respectively). The gills had the highest concentrations (r = 0.85 and 0.87, respectively). The gills had the highest concentrations of cadmium and zinc, and displayed a linear relationship to exposure concentrations (r = 0.82 and 0.87 respectively). The hepatopancreas displayed a plateau in metal concentrations and is probably the main storage site for both metals in the crayfish. The relationship of cadmium concentration to exposure concentration in the antennal glands also showed linearity (r = 0.65), while zinc levels reached a steady state level. All the remaining tissues analyzed exhibited a plateau in metal concentration

Diet of the crayfish Paranephrops zealandicus in bush and pasture streams : insights from stable isotopes and stomach analysis

International Nuclear Information System (INIS)

Hollows, J.W.; Townsend, C.R.; Collier, K.J.

2002-01-01

Crayfish (Paranephrops zealandicus White) stomachs from streams in both native bush (mainly tree leaves and dicotyledonous seeds) and exotic pasture settings (mainly grass stems and monocotyledonous seeds) were dominated by allochthonous material. More detritus occurred in stomachs in autumn-winter than in spring-summer, but quantities were similar in crayfish from native bush and pasture streams. The stomachs of larger crayfish contained a significantly greater proportion of detritus than smaller individuals. Aquatic invertebrates were the second most abundant dietary category by volume, with highest values in winter, but there were no significant differences between land uses or crayfish size classes. A wide range of invertebrates was eaten by crayfish, with mayfly nymphs, chironomid larvae, and snails predominating. The latter were numerically more prominent in crayfish from bush than pasture streams. Terrestrial invertebrates were recorded from 4% of stomachs, but there were no significant differences in relation to land use, season, or crayfish size class. Despite aquatic invertebrates making up 13 C and perhaps of microfloral origin, seems to be an important energy source for crayfish in both stream types. (author). 52 refs., 5 figs., 2 tabs

Enzymatic production of N-acetyl-d-glucosamine from crayfish shell wastes pretreated via high pressure homogenization.

Science.gov (United States)

Wei, Guoguang; Zhang, Alei; Chen, Kequan; Ouyang, Pingkai

2017-09-01

This study presents an efficient pretreatment of crayfish shell using high pressure homogenization that enables N-acetyl-d-glucosamine (GlcNAc) production by chitinase. Firstly, the chitinase from Serratia proteamaculans NJ303 was screened for its ability to degrade crayfish shell and produce GlcNAc as the sole product. Secondly, high pressure homogenization, which caused the crayfish shell to adopt a fluffy netted structure that was characterized by Scanning electron microscope (SEM), Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD), was evaluated as the best pretreatment method. In addition, the optimal conditions of high pressure homogenization of crayfish shell were determined to be five cycles at a pressure of 400bar, which achieved a yield of 3.9g/L of GlcNAc from 25g/L of crayfish shell in a batch enzymatic reaction over 1.5h. The results showed high pressure homogenization might be an efficient method for direct utilization of crayfish shell for enzymatic production of GlcNAc. Copyright © 2017 Elsevier Ltd. All rights reserved.

A REVIEW OF INTERNATIONAL BIOSECURITY POLICY DEVELOPMENT IN RELATION TO MOVEMENTS OF FRESHWATER CRAYFISH

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EDGERTON B. F.

2002-07-01

Full Text Available Freshwater crayfish are frequently traded, both alive (for human consumption or for fisheries/aquaculture stocking and as processed products (e.g. fresh or frozen, cooked or uncooked. As the experience in Europe with crayfish plague has shown, there can be significant risks of translocating pathogens with such trade. Such risks can be assessed in an import risk analysis process. This paper will concentrate on describing the principles of import risk analysis (IRA with particular reference to freshwater crayfish.

Effects of Different Social and Environmental Conditions on Established Dominance Relationships in Crayfish.

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Herberholz, Jens; Swierzbinski, Matthew E; Birke, Juliane M

2016-04-01

Like most social animals, crayfish readily form dominance relationships and linear social hierarchies when competing for limited resources. Competition often entails dyadic aggressive interactions, from which one animal emerges as the dominant and one as the subordinate. Once dominance relationships are formed, they typically remain stable for extended periods of time; thus, access to future resources is divided unequally among conspecifics. We previously showed that firmly established dominance relationships in juvenile crayfish can be disrupted by briefly adding a larger conspecific to the original pair. This finding suggested that the stability of social relationships in crayfish was highly context-dependent and more transient than previously assumed. We now report results that further identify the mechanisms underlying the destabilization of crayfish dominance relationships. We found that rank orders remained stable when conspecifics of smaller or equal size were added to the original pair, suggesting that both dominant and subordinate must be defeated by a larger crayfish in order to destabilize dominance relationships. We also found that dominance relationships remained stable when both members of the original pair were defeated by larger conspecifics in the absence of their original opponent. This showed that dominance relationships are not destabilized unless both animals experience defeat together. Lastly, we found that dominance relationships of pairs were successfully disrupted by larger intruders, although with reduced magnitude, after all chemical cues associated with earlier agonistic experiences were eliminated. These findings provide important new insights into the contextual features that regulate the stability of social dominance relationships in crayfish and probably in other species as well. © 2016 Marine Biological Laboratory.

(Non)native Speakered: Rethinking (Non)nativeness and Teacher Identity in TESOL Teacher Education

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Aneja, Geeta A.

2016-01-01

Despite its imprecision, the native-nonnative dichotomy has become the dominant paradigm for examining language teacher identity development. The nonnative English speaking teacher (NNEST) movement in particular has considered the impact of deficit framings of nonnativeness on "NNEST" preservice teachers. Although these efforts have…

Determination of lead in treated crayfish Procambarus clarkii: accumulation in different tissues

Energy Technology Data Exchange (ETDEWEB)

Pastor, A.; Medina, J.; Del Ramo, J.; Torreblanca, A.; Diaz-Mayans, J.; Hernandez, F.

1988-09-01

The continual loading of trace metals into our environment represents a water pollution problem due to their toxic effects on aquatic biota. In addition, metal ions can be incorporated into food chains and concentrated by aquatic organisms to a level that affects their physiological state. There are several investigations on the toxic effects and bioaccumulation of lead in fishes, molluscs, and crustaceans. Lake Albufera (Valencia, Spain) and the surrounding rice-field waters are subjected to large loads of sewage and toxic industrial residues (including heavy metals) from many urban wastewaters in the area. In 1978, the American red crayfish Procambarus clarkii (Girard) appeared in Lake Albufera. The crayfish have reached a high density producing ecological and agricultural economic problems in rice crops. The crayfish is being fished commercially for human consumption without adequate protection to human health. The purpose of the present study was to investigate the accumulation of lead in tissues of the crayfish P. clarkii following short term lead exposure at several sublethal concentrations. The gills, midgut glands, antennal glands and muscle were analyzed by atomic absorption spectrophotometry.

A SURVEY OF THE WHITE-CLAWED CRAYFISH,AUSTROPOTAMOBIUS PALLIPES (LEREBOULLET, AND OF WATERQUALITY IN TWO CATCHMENTS OF EASTERN IRELAND.

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DEMERS A.

2002-07-01

Full Text Available The white-clawed crayfish, Austropotamobius pallipes (Lereboullet, is the only crayfish species found in Ireland. Because of the prohibition on importation of exotic species of crayfish onto the island and of its relatively clean rivers up to now, Ireland has kept an abundant population of crayfish. A survey was conducted in the catchments of the Liffey and Boyne rivers, in eastern Ireland to assess water quality and to sample crayfish populations. The aim of the study was to evaluate the water quality requirements of the white-clawed crayfish in Ireland. Baited traps and nets were used to sample crayfish while water quality was measured with biological indices calculated from samples of macroinvertebrates. Distribution of this crayfish species is patchy in the Liffey catchment and seems to be related to factors such as soil types and water quality. They were not found in the downstream part of the river Liffey possibly due to poor water quality. In the Boyne catchment, no crayfish were found in most of the catchment. They were only present in the Kells Blackwater subcatchment. This may be due to an earlier outbreak of the fungal plague caused by Aphanomyces astaci. The disease was discovered in lakes at the top of some of the tributaries of the Boyne in 1987 and it probably spread from there through the whole catchment.

Ecological impacts of non-native species

Science.gov (United States)

Wilkinson, John W.

2012-01-01

Non-native species are considered one of the greatest threats to freshwater biodiversity worldwide (Drake et al. 1989; Allen and Flecker 1993; Dudgeon et al. 2005). Some of the first hypotheses proposed to explain global patterns of amphibian declines included the effects of non-native species (Barinaga 1990; Blaustein and Wake 1990; Wake and Morowitz 1991). Evidence for the impact of non-native species on amphibians stems (1) from correlative research that relates the distribution or abundance of a species to that of a putative non-native species, and (2) from experimental tests of the effects of a non-native species on survival, growth, development or behaviour of a target species (Kats and Ferrer 2003). Over the past two decades, research on the effects of non-native species on amphibians has mostly focused on introduced aquatic predators, particularly fish. Recent research has shifted to more complex ecological relationships such as influences of sub-lethal stressors (e.g. contaminants) on the effects of non-native species (Linder et al. 2003; Sih et al. 2004), non-native species as vectors of disease (Daszak et al. 2004; Garner et al. 2006), hybridization between non-natives and native congeners (Riley et al. 2003; Storfer et al. 2004), and the alteration of food-webs by non-native species (Nystrom et al. 2001). Other research has examined the interaction of non-native species in terms of facilitation (i.e. one non-native enabling another to become established or spread) or the synergistic effects of multiple non-native species on native amphibians, the so-called invasional meltdown hypothesis (Simerloff and Von Holle 1999). Although there is evidence that some non-native species may interact (Ricciardi 2001), there has yet to be convincing evidence that such interactions have led to an accelerated increase in the number of non-native species and cumulative impacts are still uncertain (Simberloff 2006). Applied research on the control, eradication, and

Spatial dynamics of the noble crayfish (Astacus astacus, L. in the Paklenica National Park

Directory of Open Access Journals (Sweden)

G.I.V. Klobucar

2008-07-01

Full Text Available The aim of this work was to analyse the spatial dynamics of a noble crayfish population inhabiting the Velika Paklenica Stream (Paklenica National Park, Croatia. The study was conducted in July 2000, and between March and September 2002. Crayfish were trapped by baited LiNi traps and hand-made traps at two localities over 25 nights. We recorded the precise position of the captured crayfish, their sex, and total length. Crayfish were individually marked and then released back into the stream at the same spot where they were caught. Spatial analyses included determination of movement direction, distribution type, home range, total distance travelled, and mean daily movement. A mean home range of approximately 19 m was calculated. No difference in home range between the sexes was found. There was a large individual variation in the extent of movement without any effect of sex or size.

Cadmium accumulation in the crayfish, Procambarus clarkii, using graphite furnace atomic absorption spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Diaz-Mayans, J.; Hernandez, F.; Medina, J.; Del Ramo, J.; Torreblanca, A.

1986-11-01

Lake Albufera and the surrounding rice-field waters are being subject to very heavy loads of sewage and toxic industrial residues (including heavy metals and pesticides) from the many urban and wastewaters in this area. The American red crayfish Procambarus clarkii is native to the Louisiana marshes (USA). In 1978, the crayfish appeared in Lake Albufera near Valencia (Spain), and presently, without adequate sanitary controls, the crayfish is being fished commercially for human consumption. In view of this interest, it is important to have accurate information on concentrations of cadmium in natural waters and cadmium levels of tissues of freshwaters animals used as human food, as well as the accumulation rates of this metal in this animal. In the present study, the authors investigated the accumulation of cadmium in several tissues of the red crayfish, P clarkii (Girard) from Lake Albufera following cadmium exposure. Determinations of cadmium were made by flameless atomic absorption spectroscopy and the standard additions method. Digestion of samples was made by wet ashing in open flasks with concentrated HNO/sub 3/ at 80-90/sup 0/C.

Effects of historical lead–zinc mining on riffle-dwelling benthic fish and crayfish in the Big River of southeastern Missouri, USA

Science.gov (United States)

Allert, A.L.; DiStefano, R.J.; Fairchild, J.F.; Schmitt, C.J.; McKee, M.J.; Girondo, J.A.; Brumbaugh, W.G.; May, T.W.

2013-01-01

The Big River (BGR) drains much of the Old Lead Belt mining district (OLB) in southeastern Missouri, USA, which was historically among the largest producers of lead–zinc (Pb–Zn) ore in the world. We sampled benthic fish and crayfish in riffle habitats at eight sites in the BGR and conducted 56-day in situ exposures to the woodland crayfish (Orconectes hylas) and golden crayfish (Orconectes luteus) in cages at four sites affected to differing degrees by mining. Densities of fish and crayfish, physical habitat and water quality, and the survival and growth of caged crayfish were examined at sites with no known upstream mining activities (i.e., reference sites) and at sites downstream of mining areas (i.e., mining and downstream sites). Lead, zinc, and cadmium were analyzed in surface and pore water, sediment, detritus, fish, crayfish, and other benthic macro-invertebrates. Metals concentrations in all materials analyzed were greater at mining and downstream sites than at reference sites. Ten species of fish and four species of crayfish were collected. Fish and crayfish densities were significantly greater at reference than mining or downstream sites, and densities were greater at downstream than mining sites. Survival of caged crayfish was significantly lower at mining sites than reference sites; downstream sites were not tested. Chronic toxic-unit scores and sediment probable effects quotients indicated significant risk of toxicity to fish and crayfish, and metals concentrations in crayfish were sufficiently high to represent a risk to wildlife at mining and downstream sites. Collectively, the results provided direct evidence that metals associated with historical mining activities in the OLB continue to affect aquatic life in the BGR.

First record of the invasive Australian redclaw crayfish Cherax quadricarinatus (von Martens, 1868 in the Crocodile River, Kruger National Park, South Africa

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Robin M. Petersen

2017-03-01

Full Text Available The redclaw crayfish Cherax quadricarinatus (von Martens, 1868, a robust freshwater crayfish native to Australia and Papua New Guinea, has now been recorded from the Kruger National Park (KNP. Previously absent from the Crocodile River, SAN Parks received a report in February 2016 of redclaw crayfish below the Van Graan Dam on the border of the KNP. Here, we provide evidence of the presence of redclaw crayfish in the Crocodile River. A better understanding of the redclaw crayfish distribution, habitat preferences, rate of spread and impacts on the local aquatic ecosystems in the Crocodile River is urgently required to develop mitigation strategies that minimise the spread of this invasive crayfish in the KNP and the Komati Catchment. The negative impacts of global crayfish introductions justify efforts to discourage further introductions and prevent their secondary spread. Conservation implications: A better understanding of the redclaw crayfish distribution, habitat preferences, rate of spread and impacts on the local aquatic ecosystems in the Crocodile River is urgently required to develop mitigation strategies that minimise the spread of this invasive crayfish in the Kruger National Park and the Komati Catchment.

Distribution of crayfish species in Hungarian waters

NARCIS (Netherlands)

Mercédesz, Ludányi; Peeters, E.T.H.M.; Kiss, B.; Roessink, I.

2016-01-01

Three native crayfish species, i.e.~Astacus astacus, Astacus leptodactylus and Austropotamobius torrentium, occur in Hungary. Lately, however, non-indigenous crustaceans have also invaded the country Their most recent distribution and impact on the occurrences of the native species is not clear.

A comparison of two gears for quantifying abundance of lotic-dwelling crayfish

Science.gov (United States)

Williams, Kristi; Brewer, Shannon K.; Ellersieck, Mark R.

2014-01-01

Crayfish (saddlebacked crayfish, Orconectes medius) catch was compared using a kick seine applied two different ways with a 1-m2 quadrat sampler (with known efficiency and bias in riffles) from three small streams in the Missouri Ozarks. Triplicate samples (one of each technique) were taken from two creeks and one headwater stream (n=69 sites) over a two-year period. General linear mixed models showed the number of crayfish collected using the quadrat sampler was greater than the number collected using either of the two seine techniques. However, there was no significant interaction with gear suggesting year, stream size, and channel unit type did not relate to different catches of crayfish by gear type. Variation in catch among gears was similar, as was the proportion of young-of-year individuals across samples taken with different gears or techniques. Negative binomial linear regression provided the appropriate relation between the gears which allows correction factors to be applied, if necessary, to relate catches by the kick seine to those of the quadrat sampler. The kick seine appears to be a reasonable substitute to the quadrat sampler in these shallow streams, with the advantage of ease of use and shorter time required per sample.

Temporal variation in the prevalence of the crayfish plague pathogen, Aphanomyces astaci, in three Czech spiny-cheek crayfish populations

Czech Academy of Sciences Publication Activity Database

Matasová, K.; Kozubíková, E.; Svoboda, J.; Jarošík, Vojtěch; Petrusek, A.

-, č. 401 (2011), s. 1-9 ISSN 1961-9502 R&D Projects: GA MŠk LC06073 Institutional research plan: CEZ:AV0Z60050516 Keywords : crayfish plague * molecular methosd * dominance Subject RIV: EH - Ecology, Behaviour Impact factor: 1.520, year: 2011

Comparing macrophyte herbivory by introduced Louisiana crayfish ...

African Journals Online (AJOL)

The omnivorous Louisiana crayfish, Procambarus clarkii, has caused significant changes to macrophyte communities worldwide and may have similar negative effects in Kenya if used as a biological control agent for snails harbouring human schistosomes. Here we examine how herbivory by the introduced Louisiana ...

Water chemistry and endangered white-clawed Crayfish: a literature review and field study of water chemistry association in Austropotamobius pallipes

Directory of Open Access Journals (Sweden)

Haddaway N.R.

2015-01-01

Full Text Available Populations of the endangered white-clawed crayfish (Austropotamobius pallipes have rapidly declined in distribution and density in recent decades as a result of invasive crayfish, disease and habitat degradation. The species is thought to be particularly sensitive to water chemistry, and has been proposed as a bio-indicator of water quality. Here we detail the results of a systematic review of the literature regarding the chemistry of waterbodies inhabited by white-clawed crayfish, along with a wide-scale field study of the chemistry of crayfish-inhabited waterbodies in the UK. We use these data to examine potentially significant variables influencing crayfish distribution. Several variables appear to have thresholds that affect crayfish distribution; crayfish presence was associated with high dissolved oxygen, low conductivity, ammonium, sodium, and phosphate, and to a lesser extent low sulphate, nitrate, and total suspended solids. Some variables (magnesium, potassium, sodium, sulphate, nitrate, and total suspended solids may be tolerated at moderate to high concentrations in isolation (indicated by the presence of some populations in high levels of these variables, but suites of chemical conditions may act synergistically in situ and must be considered together. Recent efforts to conserve white-clawed crayfish have included relocations to Ark Sites; novel protected habitats with reduced risk of the introduction of disease, invasive crayfish and habitat degradation. We use our findings to propose the first detailed guidelines for common water chemistry variables of potential Ark Sites for the conservation of the species throughout its European range.

Crayfish impact desert river ecosystem function and litter-dwelling invertebrate communities through association with novel detrital resources.

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Eric K Moody

Full Text Available Shifts in plant species distributions due to global change are increasing the availability of novel resources in a variety of ecosystems worldwide. In semiarid riparian areas, hydric pioneer tree species are being replaced by drought-tolerant plant species as water availability decreases. Additionally, introduced omnivorous crayfish, which feed upon primary producers, allochthonous detritus, and benthic invertebrates, can impact communities at multiple levels through both direct and indirect effects mediated by drought-tolerant plants. We tested the impact of both virile crayfish (Orconectes virilis and litter type on benthic invertebrates and the effect of crayfish on detrital resources across a gradient of riparian vegetation drought-tolerance using field cages with leaf litter bags in the San Pedro River in Southeastern Arizona. Virile crayfish increased breakdown rate of novel drought-tolerant saltcedar (Tamarix ramosissima, but did not impact breakdown of drought-tolerant seepwillow (Baccharis salicifolia or hydric Fremont cottonwood (Populus fremontii and Gooding's willow (Salix goodingii. Effects on invertebrate diversity were observed at the litter bag scale, but no effects were found at the cage scale. Crayfish decreased alpha diversity of colonizing macroinvertebrates, but did not affect beta diversity. In contrast, the drought-tolerant litter treatment decreased beta diversity relative to hydric litter. As drought-tolerant species become more abundant in riparian zones, their litter will become a larger component of the organic matter budget of desert streams which may serve to homogenize the litter-dwelling community and support elevated populations of virile crayfish. Through impacts at multiple trophic levels, crayfish have a significant effect on desert stream ecosystems.

Range extensions of three crayfishes (Faxonius yanahlindus, F. placidus, and F. erichsonianus) into Mississippi

Science.gov (United States)

Susan B. Adams; Robert L. Jones

2018-01-01

We report 3 new state crayfish records from the Tennessee River drainage in Tishomingo County, Mississippi: 1 is a re-identification of previously published material, and 2 are from unpublished collections. Faxonius yanahlindus (Spinywrist Crayfish), recently described from the middle Tennessee River drainage in northwest Alabama and southern...

Nutritional treatment of cancer cachexia in rats. Use of a diet formulated with a crayfish enzymatic extract.

Science.gov (United States)

Cremades, Olga; Parrado, Juan; Jover, María; Collantes de Terán, Laura; Gutiérrez, Juan Francisco; Bautista Palomas, Juan D

2007-09-01

Terminal cancer-associated cachexia, characterized by a marked weight loss, anorexia, asthenia and anemia, is usually associated with a malnutrition status. To investigate whether a diet formulated with a crayfish enzymatic extract, enriched in essential amino acids, omega-3 fatty acids, and astaxanthin, would be effective for the treatment of cancer-associated cachexias, by decreasing mortality and morbidity rates in cachectic rats and/or improving survival. Two types of diet were used: a standard diet and one formulated with crayfish enzymatic extract. Rats were divided into two groups (24 animals per group): one without tumor (T-) and the other with tumor (T+) (AH-130 Yoshida ascites hepatoma). Each group was further divided into two subgroups (12 animals per subgroup). Two subgroups (T-(standard) and T+(standard)) were fed the standard diet and the other two (T-(CFEE) and T+(CFEE)) the crayfish enzymatic extract one for four weeks, after which different tissue and plasma parameters were studied. The implantation of the tumor resulted in a considerable loss of muscle and adipose tissue mass in both groups, but the loss of muscle and fat was lower in the group fed the crayfish enzymatic extract diet. There was also a concomitant increase in the plasma concentration of TNF-alpha, although the increase was smaller in the crayfish enzymatic extract-treated group. This study shows that although the treatment of cachetic rats with the crayfish enzymatic extract diet did not revert the cachexia, it increased survival (57.1% vs. 25.9% in the group treated with crayfish enzymatic extract and standard diets, respectively) and meliorated the cachexia symptoms--anorexia and body mass loss (muscle and adipose tissue).

Word Durations in Non-Native English

Science.gov (United States)

Baker, Rachel E.; Baese-Berk, Melissa; Bonnasse-Gahot, Laurent; Kim, Midam; Van Engen, Kristin J.; Bradlow, Ann R.

2010-01-01

In this study, we compare the effects of English lexical features on word duration for native and non-native English speakers and for non-native speakers with different L1s and a range of L2 experience. We also examine whether non-native word durations lead to judgments of a stronger foreign accent. We measured word durations in English paragraphs read by 12 American English (AE), 20 Korean, and 20 Chinese speakers. We also had AE listeners rate the `accentedness' of these non-native speakers. AE speech had shorter durations, greater within-speaker word duration variance, greater reduction of function words, and less between-speaker variance than non-native speech. However, both AE and non-native speakers showed sensitivity to lexical predictability by reducing second mentions and high frequency words. Non-native speakers with more native-like word durations, greater within-speaker word duration variance, and greater function word reduction were perceived as less accented. Overall, these findings identify word duration as an important and complex feature of foreign-accented English. PMID:21516172

Importance of small fishes and invasive crayfish in otter Lutra lutra diet in an English chalk stream

OpenAIRE

Britton, J.R.; Berry, M.; Sewell, S.; Lees, C.; Reading, P.

2017-01-01

The diet composition of the European otter Lutra lutra was assessed using spraint analysis in the Hampshire Avon, a lowland chalk stream in Southern England, over an 18-month period. Small cyprinid fishes were the main prey item taken in all seasons, with bullhead Cottus gobio and stone loach Barbatula barbatula also important; there were relatively few larger fishes of interest to fisheries found. There were significant seasonal differences in diet composition by season, with signal crayfish...

Semantic and phonetic enhancements for speech-in-noise recognition by native and non-native listeners.

Science.gov (United States)

Bradlow, Ann R; Alexander, Jennifer A

2007-04-01

Previous research has shown that speech recognition differences between native and proficient non-native listeners emerge under suboptimal conditions. Current evidence has suggested that the key deficit that underlies this disproportionate effect of unfavorable listening conditions for non-native listeners is their less effective use of compensatory information at higher levels of processing to recover from information loss at the phoneme identification level. The present study investigated whether this non-native disadvantage could be overcome if enhancements at various levels of processing were presented in combination. Native and non-native listeners were presented with English sentences in which the final word varied in predictability and which were produced in either plain or clear speech. Results showed that, relative to the low-predictability-plain-speech baseline condition, non-native listener final word recognition improved only when both semantic and acoustic enhancements were available (high-predictability-clear-speech). In contrast, the native listeners benefited from each source of enhancement separately and in combination. These results suggests that native and non-native listeners apply similar strategies for speech-in-noise perception: The crucial difference is in the signal clarity required for contextual information to be effective, rather than in an inability of non-native listeners to take advantage of this contextual information per se.

First evidence of crayfish plaque agent in populations of the marbled caryfish (Procambarus fallux forma virginalis)

NARCIS (Netherlands)

Keller, N.S.; Pfeiffer, M.; Roessink, I.; Schulz, R.; Schrimpf, A.

2014-01-01

The introduction of non-indigenous species and associated diseases can cause declines in indigenous flora and fauna and threaten local biodiversity. The crayfish plague pathogen (Aphanomyces astaci), carried and transmitted by latent infected North American crayfish, can lead to high mortalities in

Bioaccumulation of lead nitrate in freshwater crayfish (Astacus leptodactylus) tissues under aquaculture conditions.

Science.gov (United States)

Naghshbandi, N; Zare, S; Heidari, R; Soleimani Palcheglu, S

2007-09-15

The aim of this research was to evaluate the amount of lead in the tissue of Astacus leptodactylus especially in their muscle which the consumed part of their body. In this study the crayfish was exposed to intermediate concentration of lead nitrate (500 microg L(-1)) for periods up to 3 weeks. In the first, second and third weeks bioaccumulation in various tissues was under investigation. The data of toxicological analysis obtained by the method of atomic absorption revealed that the levels of bioaccumulation of metal are different in various tissues of this crayfish. The accumulation of the lead in gills was the highest and in muscles was lowest degree. The amount of heavy metals in the tissues of crayfish was as follow. Gills>exoskeleton>hepatopancreas (digestive glands)>digestive tract>green gland>testis and ovary>muscles.

Comparative analysis of crayfish marketing in selected markets of ...

African Journals Online (AJOL)

Comparative analysis of crayfish marketing in selected markets of Akwa Ibom and Abia States, Nigeria. ... It specifically looked at market integration, costs and return, marketing margin, marketing ... EMAIL FULL TEXT EMAIL FULL TEXT

ECOLOGICAL CHARACTERISATION OF STREAMS IN TUSCANY (ITALY FOR THE MANAGEMENT OF THE THREATENED CRAYFISH AUSTROPOTAMOBIUS PALLIPES COMPLEX

Directory of Open Access Journals (Sweden)

RENAI B.

2006-01-01

Full Text Available Any initiative aimed at the management of a threatened species needs a good knowledge of its environmental requirements. Aims of this study were to individuate suitable areas for the reintroduction of crayfish species belonging to the Austropotamobius pallipes complex and to evaluate the causes of the local extinction in Tuscany (Italy of some populations. Between May 2003 and September 2004, we collected ecological data from 19 streams of 4 catchments, 9 watercourses where crayfish were present (WI and 10 where they were present in the recent past and absent now (WO, and we compared them. Multivariate analyses were performed using chemico-physical and biotic parameters to examine the relationships between their values and the presence of crayfish. The results did not allow us to find significant differences between the two categories of streams, suggesting their suitability for crayfish reintroduction.

Comparative study of freshwater crayfish, Cherax spp. (crustaceae: decapoda: parastacidae) from Papua, Indonesia based on length-weight analysis

Science.gov (United States)

Hamidah, H.; Abinawanto, Bowolaksono, A.

2017-07-01

The freshwater crayfish is one of the most important fish species as the protein resources. Lake and rivers are the habitat of crayfish in Papua. Morphological characters of crayfish, such as color, total body lengths (L) and body weight (W) were influenced by the habitat. The purpose of the study, therefore, was to compare the total body length and body weight as well as the unique color of crayfish from Uter lake (Atinjo district), Seremuk river (Haha village), Baliem river (Pike village; Hubukiak district, Jayawijaya), and Baliem river (Wesaput village; Wesaput district). Length-weight (body length; LB versus wet weight; WWT) relationships were determined for male and female crayfish (Cherax spp.) The length-weight relationships of total individuals was W = 0,022215.L3,159. This regression differed significantly (R2 = 97.5 %) between locations. Both males and females exhibited positive allometric growth as statistical difference was observed in the mean of the wet weight and body length between males and females. Besides, Canonical function was subjected to determine population distribution based on length-weight data.

Ecological impacts of non-native species: Chapter 2

Science.gov (United States)

Pilliod, David S.; Griffiths, R.A.; Kuzmin, S.L.; Heatwole, Harold; Wilkinson, John W.

2012-01-01

Non-native species are considered one of the greatest threats to freshwater biodiversity worldwide (Drake et al. 1989; Allen and Flecker 1993; Dudgeon et al. 2005). Some of the first hypotheses proposed to explain global patterns of amphibian declines included the effects of non-native species (Barinaga 1990; Blaustein and Wake 1990; Wake and Morowitz 1991). Evidence for the impact of non-native species on amphibians stems (1) from correlative research that relates the distribution or abundance of a species to that of a putative non-native species, and (2) from experimental tests of the effects of a non-native species on survival, growth, development or behaviour of a target species (Kats and Ferrer 2003). Over the past two decades, research on the effects of non-native species on amphibians has mostly focused on introduced aquatic predators, particularly fish. Recent research has shifted to more complex ecological relationships such as influences of sub-lethal stressors (e.g. contaminants) on the effects of non-native species (Linder et al. 2003; Sih et al. 2004), non-native species as vectors of disease (Daszak et al. 2004; Garner et al. 2006), hybridization between non-natives and native congeners (Riley et al. 2003; Storfer et al. 2004), and the alteration of food-webs by non-native species (Nystrom et al. 2001). Other research has examined the interaction of non-native species in terms of facilitation (i.e. one non-native enabling another to become established or spread) or the synergistic effects of multiple non-native species on native amphibians, the so-called invasional meltdown hypothesis (Simerloff and Von Holle 1999). Although there is evidence that some non-native species may interact (Ricciardi 2001), there has yet to be convincing evidence that such interactions have led to an accelerated increase in the number of non-native species and cumulative impacts are still uncertain (Simberloff 2006). Applied research on the control, eradication, and

How much does language proficiency by non-native listeners influence speech audiometric tests in noise?

Science.gov (United States)

Warzybok, Anna; Brand, Thomas; Wagener, Kirsten C; Kollmeier, Birger

2015-01-01

The current study investigates the extent to which the linguistic complexity of three commonly employed speech recognition tests and second language proficiency influence speech recognition thresholds (SRTs) in noise in non-native listeners. SRTs were measured for non-natives and natives using three German speech recognition tests: the digit triplet test (DTT), the Oldenburg sentence test (OLSA), and the Göttingen sentence test (GÖSA). Sixty-four non-native and eight native listeners participated. Non-natives can show native-like SRTs in noise only for the linguistically easy speech material (DTT). Furthermore, the limitation of phonemic-acoustical cues in digit triplets affects speech recognition to the same extent in non-natives and natives. For more complex and less familiar speech materials, non-natives, ranging from basic to advanced proficiency in German, require on average 3-dB better signal-to-noise ratio for the OLSA and 6-dB for the GÖSA to obtain 50% speech recognition compared to native listeners. In clinical audiology, SRT measurements with a closed-set speech test (i.e. DTT for screening or OLSA test for clinical purposes) should be used with non-native listeners rather than open-set speech tests (such as the GÖSA or HINT), especially if a closed-set version in the patient's own native language is available.

ANNUAL ACTIVITY OF THE NOBLE CRAYFISH (ASTACUS ASTACUS IN THE ORLJAVA RIVER (CROATIA

Directory of Open Access Journals (Sweden)

FALLER M.

2006-07-01

Full Text Available We studied the annual activity of the noble crayfish (Astacus astacus at three sites along the Orljava River, in the continental part of Croatia, between August 2003 and September 2004. Each site represented the typical characteristics of the upper, middle and lower section of the river (5, 24 and 37 km from the spring, respectively. The biggest population size was recorded on the most upstream site, with greatest structural variability of bottom, high biotic index, and the lowest mean water temperature. Males dominated in catch during the whole research period (total sex ratio was 1.77 males: 1 female. The number of caught crayfish fluctuated during the year and their activity was positively correlated with the water temperature. The crayfish catch within the two downstream sites was dramatically lower in the autumn 2004 then the year before. No obvious reason could be found; therefore we concluded that this was probably result of natural fluctuations in population. Males were significantly longer than females on all three sites. Males and females had similar percentages of injuries, mainly on claws and antennae. Crayfish were active during the whole year, even when water temperature was just 1°C. Phases of life cycle (moulting, active cement glands, mating, hatchlings occurred a month later in our population than in the Northern Europe populations, probably as a consequence of differences in the climate.

Histological analysis of thelohaniasis in white-clawed crayfish Austropotamobius pallipes complex

Directory of Open Access Journals (Sweden)

Quaglio F.

2011-09-01

Full Text Available From 2004 to 2006, a parasitological survey aimed at the detection of the microsporidian parasite Thelohania contejeani Henneguy was carried out on 177 wild white-clawed crayfish (Austropotamobius pallipes complex captured in six streams and rivers of the province of Belluno in north-eastern Italy. Microscopical examination of the skeletal muscles, and histological analysis applying different histochemical stains to full transverse and sagittal sections of the cephalothorax and abdomen were carried out. Transmission electron microscopy (TEM was also conducted on the parasites recovered during the survey. Out of 177 crayfish examined, Thelohania contejeani (Microsporidia, Thelohaniidae was present in only one crayfish from the Vena d’oro creek. The parasite was detected in the skeletal muscles in several developmental stages, including mature spores, which represented the most common stage recovered. Sporophorous vesicles were also present. Histological examination revealed that the fibres of the skeletal, cardiac and intestinal muscles were filled with spores. Melanin infiltrations were focally present in the infected striated muscles. The gill phagocytic nephrocytes were engulfed by small masses of spores. Among the staining techniques applied, Crossman’s trichrome stain represented the most effective method of detecting T. contejeani.

Reanalysis and semantic persistence in native and non-native garden-path recovery.

Science.gov (United States)

Jacob, Gunnar; Felser, Claudia

2016-01-01

We report the results from an eye-movement monitoring study investigating how native and non-native speakers of English process temporarily ambiguous sentences such as While the gentleman was eating the burgers were still being reheated in the microwave, in which an initially plausible direct-object analysis is first ruled out by a syntactic disambiguation (were) and also later on by semantic information (being reheated). Both participant groups showed garden-path effects at the syntactic disambiguation, with native speakers showing significantly stronger effects of ambiguity than non-native speakers in later eye-movement measures but equally strong effects in first-pass reading times. Ambiguity effects at the semantic disambiguation and in participants' end-of-trial responses revealed that for both participant groups, the incorrect direct-object analysis was frequently maintained beyond the syntactic disambiguation. The non-native group showed weaker reanalysis effects at the syntactic disambiguation and was more likely to misinterpret the experimental sentences than the native group. Our results suggest that native language (L1) and non-native language (L2) parsing are similar with regard to sensitivity to syntactic and semantic error signals, but different with regard to processes of reanalysis.

A global review of freshwater crayfish temperature tolerance, preference, and optimal growth

Science.gov (United States)

Westhoff, Jacob T.; Rosenberger, Amanda E.

2016-01-01

Conservation efforts, environmental planning, and management must account for ongoing ecosystem alteration due to a changing climate, introduced species, and shifting land use. This type of management can be facilitated by an understanding of the thermal ecology of aquatic organisms. However, information on thermal ecology for entire taxonomic groups is rarely compiled or summarized, and reviews of the science can facilitate its advancement. Crayfish are one of the most globally threatened taxa, and ongoing declines and extirpation could have serious consequences on aquatic ecosystem function due to their significant biomass and ecosystem roles. Our goal was to review the literature on thermal ecology for freshwater crayfish worldwide, with emphasis on studies that estimated temperature tolerance, temperature preference, or optimal growth. We also explored relationships between temperature metrics and species distributions. We located 56 studies containing information for at least one of those three metrics, which covered approximately 6 % of extant crayfish species worldwide. Information on one or more metrics existed for all 3 genera of Astacidae, 4 of the 12 genera of Cambaridae, and 3 of the 15 genera of Parastacidae. Investigations employed numerous methodological approaches for estimating these parameters, which restricts comparisons among and within species. The only statistically significant relationship we observed between a temperature metric and species range was a negative linear relationship between absolute latitude and optimal growth temperature. We recommend expansion of studies examining the thermal ecology of freshwater crayfish and identify and discuss methodological approaches that can improve standardization and comparability among studies.

Natural crayfish clone as emerging model for various biological ...

Indian Academy of Sciences (India)

Home; Journals; Journal of Biosciences; Volume 36; Issue 2. Marmorkrebs: Natural crayfish clone as emerging model for various biological disciplines. Günter Vogt. Mini-review Volume 36 Issue 2 June 2011 pp 377-382. Fulltext. Click here to view fulltext PDF. Permanent link:

Non-native educators in English language teaching

CERN Document Server

Braine, George

2013-01-01

The place of native and non-native speakers in the role of English teachers has probably been an issue ever since English was taught internationally. Although ESL and EFL literature is awash, in fact dependent upon, the scrutiny of non-native learners, interest in non-native academics and teachers is fairly new. Until recently, the voices of non-native speakers articulating their own concerns have been even rarer. This book is a response to this notable vacuum in the ELT literature, providing a forum for language educators from diverse geographical origins and language backgrounds. In addition to presenting autobiographical narratives, these authors argue sociopolitical issues and discuss implications for teacher education, all relating to the theme of non-native educators in ETL. All of the authors are non-native speakers of English. Some are long established professionals, whereas others are more recent initiates to the field. All but one received part of the higher education in North America, and all excep...

Political skill: explaining the effects of nonnative accent on managerial hiring and entrepreneurial investment decisions.

Science.gov (United States)

Huang, Laura; Frideger, Marcia; Pearce, Jone L

2013-11-01

We propose and test a new theory explaining glass-ceiling bias against nonnative speakers as driven by perceptions that nonnative speakers have weak political skill. Although nonnative accent is a complex signal, its effects on assessments of the speakers' political skill are something that speakers can actively mitigate; this makes it an important bias to understand. In Study 1, White and Asian nonnative speakers using the same scripted responses as native speakers were found to be significantly less likely to be recommended for a middle-management position, and this bias was fully mediated by assessments of their political skill. The alternative explanations of race, communication skill, and collaborative skill were nonsignificant. In Study 2, entrepreneurial start-up pitches from national high-technology, new-venture funding competitions were shown to experienced executive MBA students. Nonnative speakers were found to have a significantly lower likelihood of receiving new-venture funding, and this was fully mediated by the coders' assessments of their political skill. The entrepreneurs' race, communication skill, and collaborative skill had no effect. We discuss the value of empirically testing various posited reasons for glass-ceiling biases, how the importance and ambiguity of political skill for executive success serve as an ostensibly meritocratic cover for nonnative speaker bias, and other theoretical and practical implications of this work. (c) 2013 APA, all rights reserved.

The Sensitivity of the Crayfish Reward System to Mammalian Drugs of Abuse.

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Shipley, Adam T; Imeh-Nathaniel, Adebobola; Orfanakos, Vasiliki B; Wormack, Leah N; Huber, Robert; Nathaniel, Thomas I

2017-01-01

The idea that addiction occurs when the brain is not able to differentiate whether specific reward circuits were triggered by adaptive natural rewards or falsely activated by addictive drugs exist in several models of drug addiction. The suitability of crayfish ( Orconectes rusticus ) for drug addiction research arises from developmental variation of growth, life span, reproduction, behavior and some quantitative traits, especially among isogenic mates reared in the same environment. This broad spectrum of traits makes it easier to analyze the effect of mammalian drugs of abuse in shaping behavioral phenotype. Moreover, the broad behavioral repertoire allows the investigation of self-reinforcing circuitries involving appetitive and exploratory motor behavior, while the step-wise alteration of the phenotype by metamorphosis allows accurate longitudinal analysis of different behavioral states. This paper reviews a series of recent experimental findings that evidence the suitability of crayfish as an invertebrate model system for the study of drug addiction. Results from these studies reveal that unconditioned exposure to mammalian drugs of abuse produces a variety of stereotyped behaviors. Moreover, if presented in the context of novelty, drugs directly stimulate exploration and appetitive motor patterns along with molecular processes for drug conditioned reward. Findings from these studies indicate the existence of drug sensitive circuitry in crayfish that facilitates exploratory behavior and appetitive motor patterns via increased incentive salience of environmental stimuli or by increasing exploratory motor patterns. This work demonstrates the potential of crayfish as a model system for research into the neural mechanisms of addiction, by contributing an evolutionary, comparative context to our understanding of natural reward as an important life-sustaining process.

The Sensitivity of the Crayfish Reward System to Mammalian Drugs of Abuse

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Adam T. Shipley

2017-12-01

Full Text Available The idea that addiction occurs when the brain is not able to differentiate whether specific reward circuits were triggered by adaptive natural rewards or falsely activated by addictive drugs exist in several models of drug addiction. The suitability of crayfish (Orconectes rusticus for drug addiction research arises from developmental variation of growth, life span, reproduction, behavior and some quantitative traits, especially among isogenic mates reared in the same environment. This broad spectrum of traits makes it easier to analyze the effect of mammalian drugs of abuse in shaping behavioral phenotype. Moreover, the broad behavioral repertoire allows the investigation of self-reinforcing circuitries involving appetitive and exploratory motor behavior, while the step-wise alteration of the phenotype by metamorphosis allows accurate longitudinal analysis of different behavioral states. This paper reviews a series of recent experimental findings that evidence the suitability of crayfish as an invertebrate model system for the study of drug addiction. Results from these studies reveal that unconditioned exposure to mammalian drugs of abuse produces a variety of stereotyped behaviors. Moreover, if presented in the context of novelty, drugs directly stimulate exploration and appetitive motor patterns along with molecular processes for drug conditioned reward. Findings from these studies indicate the existence of drug sensitive circuitry in crayfish that facilitates exploratory behavior and appetitive motor patterns via increased incentive salience of environmental stimuli or by increasing exploratory motor patterns. This work demonstrates the potential of crayfish as a model system for research into the neural mechanisms of addiction, by contributing an evolutionary, comparative context to our understanding of natural reward as an important life-sustaining process.

Short Note Invasive Australian crayfish Cherax quadricarinatus in ...

African Journals Online (AJOL)

Most crayfish were between 50 and 59.9 mm carapace length. Males (average 82.6 g) were significantly heavier than females (37.2 g) and males were larger in carapace length, carapace width, chela length and chela width. A feral population of C. quadricarinatus is now established in the Sanyati Basin. Possible modes of ...

ROUNDTABLE SESSION 3: PHYLOGENY OF EUROPEAN CRAYFISH – IMPROVING THE TAXONOMY OF EUROPEAN CRAYFISH FOR A BETTER CONSERVATION

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SCHULZ H. K.

2005-07-01

Full Text Available This paper summarizes the various themes discussed in a roundtable session on the uses and usefulness of genetics for conservation of our European crayfish heritage. After reviewing the importance of characterizing the different genetic stocks (ESU: Evolutionary Significant Units of a species, where morphological criteria used for taxonomy, are utilizable with caution, the present state of knowledge of the phylogeny of European species was determined, in particular for the genus Austropotamobius which occupies most studies. There was a lively debate on the elevation to species rank of A. italicus. The status of knowledge of the taxonomy of Astacus astacus has been presented. Finally, given a major increase in works describing the genetic variability of natural populations of European crayfish, it was evident that an up to date inventory of the different research teams in this field should be developed, for several reasons – (i to describe these teams and their managers (thus facilitating contact (ii to list the species studied and the markers used (iii to give some recommendations on standardizing the use of certain markers or genes so as to allow comparison between the results collected by the various teams, and to apply them on a broader geographic scale.

Antibacterial activity of hemocyanin from red swamp crayfish (Procambarus clarkii).

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Qin, Zhendong; Babu, V Sarath; Wan, Quanyuan; Muhammad, Asim; Li, Jun; Lan, Jiangfeng; Lin, Li

2018-04-01

Hemocyanins (HMC): the copper-containing respiratory proteins present in invertebrate hemolymph, which plays many essential roles in the immune system. Currently, little is known about the HMC domains of Procambarus clarkii (P. clarkii) and their function in antimicrobial immune response. In this present study, we comparatively studied the expression pattern of native PcHMC with the three recombinant proteins of variable domains of crayfish hemocyanin (PcHMC-N, N-terminal domain of hemocyanin; PcHMC-T, tyrosinase domain of hemocyanin; PcHMC-C, C-terminal domain of hemocyanin). The results showed that three purified recombinant proteins had a strong binding to various bacteria and lipopolysaccharides that further highly agglutinated. The HMCs recombinant proteins showed strong antibacterial activity against V. parahaemolyticus and S. aureus by bacterial growth inhibition, phenoloxidase (PO) and phagocytosis assays. Specifically, rPcHMC1-T and rPcHMC1-C inhibited both the bacteria efficiently, rPcHMC1-T was highly upregulated the PO activity than the other recombinant proteins. Whereas, recombinant proteins pretreated crayfish hemocytes participated in phagocytosis activity, rPcHMC1-N and rPcHMC1-C proteins had a profound effect than the rPcHMC1-T on S. aureus and V. parahaemolyticus phagocytosis. The crayfish hemocyanin domains clearly exhibited antibacterial and phagocytic activities against both the bacteria, suggesting that its variable domains of hemocyanin have the different function on specific pathogen during the assault of pathogens. Copyright © 2018 Elsevier Ltd. All rights reserved.

Crayfish: a newly recognized vehicle for vibrio infections.

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Bean, N H; Maloney, E K; Potter, M E; Korazemo, P; Ray, B; Taylor, J P; Seigler, S; Snowden, J

1998-10-01

We conducted a 1-year case-control study of sporadic vibrio infections to identify risk factors related to consumption of seafood products in two coastal areas of Louisiana and Texas. Twenty-six persons with sporadic vibrio infections and 77 matched controls were enrolled. Multivariate analysis revealed that crayfish (P Vibrio parahemolyticus infection (OR 9.24, P vibrio infection.

CRAYFISH AND ITS CULTURE IN UKRAINE. THEMATIC REFERENCES LIST

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I. Hrytsyniak

2014-09-01

Full Text Available Purpose. To compile a thematic references list on the problems of biology, physiology, pathology and crayfish breeding in Ukraine. Methodology. As the search base for the realization of the purpose was the scientific library stock of the Institute of Fisheries NAAS. The methods that have been preferred were both integrated and selective. Findings. We prepared a thematic reference list of the main scientific works, such as collections of scientific papers, proceedings of international scientific conferences, articles and candidate’s thesis abstracts on the biology of crustaceans and their cultivation in Ukraine, including the literature sources since 1958. The bibliography contains 37 publications of the Institute of Fisheries NAAS scientific library stock, in alphabetical order, and described according to DSTU GOST 7.1:2006 «System of standards on information, librarianship and publishing. Bibliographic entry. Bibliographic description. General requirements and rules». Practical value. The list may be helpful for experts, scientists, students, who are interested in problems of crayfish biology and culture.

Drug-sensitive reward in crayfish: an invertebrate model system for the study of SEEKING, reward, addiction, and withdrawal.

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Huber, Robert; Panksepp, Jules B; Nathaniel, Thomas; Alcaro, Antonio; Panksepp, Jaak

2011-10-01

In mammals, rewarding properties of drugs depend on their capacity to activate appetitive motivational states. With the underlying mechanisms strongly conserved in evolution, invertebrates have recently emerged as a powerful new model in addiction research. In crayfish natural reward has proven surprisingly sensitive to human drugs of abuse, opening an unlikely avenue of research into the basic biological mechanisms of drug addiction. In a series of studies we first examined the presence of natural reward systems in crayfish, then characterized its sensitivity to a wide range of human drugs of abuse. A conditioned place preference (CPP) paradigm was used to demonstrate that crayfish seek out those environments that had previously been paired with the psychostimulants cocaine and amphetamine, and the opioid morphine. The administration of amphetamine exerted its effects at a number of sites, including the stimulation of circuits for active exploratory behaviors (i.e., SEEKING). A further study examined morphine-induced reward, extinction and reinstatement in crayfish. Repeated intra-circulatory infusions of morphine served as a reward when paired with distinct visual or tactile cues. Morphine-induced CPP was extinguished after repeated saline injections. Following this extinction phase, morphine-experienced crayfish were once again challenged with the drug. The priming injections of morphine reinstated CPP at all tested doses, suggesting that morphine-induced CPP is unrelenting. In an exploration of drug-associated behavioral sensitization in crayfish we concurrently mapped measures of locomotion and rewarding properties of morphine. Single and repeated intra-circulatory infusions of morphine resulted in persistent locomotory sensitization, even 5 days following the infusion. Moreover, a single dose of morphine was sufficient to induce long-term behavioral sensitization. CPP for morphine and context-dependent cues could not be disrupted over a drug free period of 5

The potential for using red claw crayfish and hybrid African catfish as biological control agents for Schistosoma host snails

NARCIS (Netherlands)

Monde, C.; Syampungani, S.; Rico, A.; Brink, van den P.J.

2017-01-01

The potential of red claw crayfish and hybrid African catfish (Clarias gariepinus and Clarias ngamensis) as predators for Schistosoma host snails was evaluated in 2014 by monitoring the consumption of snails by crayfish and catfish in experimental tanks over time under laboratory conditions. After

Credibility of native and non-native speakers of English revisited: Do non-native listeners feel the same?

OpenAIRE

Hanzlíková, Dagmar; Skarnitzl, Radek

2017-01-01

This study reports on research stimulated by Lev-Ari and Keysar (2010) who showed that native listeners find statements delivered by foreign-accented speakers to be less true than those read by native speakers. Our objective was to replicate the study with non-native listeners to see whether this effect is also relevant in international communication contexts. The same set of statements from the original study was recorded by 6 native and 6 nonnative speakers of English. 121 non-native listen...

Can heat waves change the trophic role of the world's most invasive crayfish? Diet shifts in Procambarus clarkii.

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Carreira, Bruno M; Segurado, Pedro; Laurila, Anssi; Rebelo, Rui

2017-01-01

In the Mediterranean basin, the globally increasing temperatures are expected to be accompanied by longer heat waves. Commonly assumed to benefit cold-limited invasive alien species, these climatic changes may also change their feeding preferences, especially in the case of omnivorous ectotherms. We investigated heat wave effects on diet choice, growth and energy reserves in the invasive red swamp crayfish, Procambarus clarkii. In laboratory experiments, we fed juvenile and adult crayfish on animal, plant or mixed diets and exposed them to a short or a long heat wave. We then measured crayfish survival, growth, body reserves and Fulton's condition index. Diet choices of the crayfish maintained on the mixed diet were estimated using stable isotopes (13C and 15N). The results suggest a decreased efficiency of carnivorous diets at higher temperatures, as juveniles fed on the animal diet were unable to maintain high growth rates in the long heat wave; and a decreased efficiency of herbivorous diets at lower temperatures, as juveniles in the cold accumulated less body reserves when fed on the plant diet. Heat wave treatments increased the assimilation of plant material, especially in juveniles, allowing them to sustain high growth rates in the long heat wave. Contrary to our expectations, crayfish performance decreased in the long heat wave, suggesting that Mediterranean summer heat waves may have negative effects on P. clarkii and that they are unlikely to boost its populations in this region. Although uncertain, it is possible that the greater assimilation of the plant diet resulted from changes in crayfish feeding preferences, raising the hypotheses that i) heat waves may change the predominant impacts of this keystone species and ii) that by altering species' trophic niches, climate change may alter the main impacts of invasive alien species.

Can heat waves change the trophic role of the world's most invasive crayfish? Diet shifts in Procambarus clarkii.

Directory of Open Access Journals (Sweden)

Bruno M Carreira

Full Text Available In the Mediterranean basin, the globally increasing temperatures are expected to be accompanied by longer heat waves. Commonly assumed to benefit cold-limited invasive alien species, these climatic changes may also change their feeding preferences, especially in the case of omnivorous ectotherms. We investigated heat wave effects on diet choice, growth and energy reserves in the invasive red swamp crayfish, Procambarus clarkii. In laboratory experiments, we fed juvenile and adult crayfish on animal, plant or mixed diets and exposed them to a short or a long heat wave. We then measured crayfish survival, growth, body reserves and Fulton's condition index. Diet choices of the crayfish maintained on the mixed diet were estimated using stable isotopes (13C and 15N. The results suggest a decreased efficiency of carnivorous diets at higher temperatures, as juveniles fed on the animal diet were unable to maintain high growth rates in the long heat wave; and a decreased efficiency of herbivorous diets at lower temperatures, as juveniles in the cold accumulated less body reserves when fed on the plant diet. Heat wave treatments increased the assimilation of plant material, especially in juveniles, allowing them to sustain high growth rates in the long heat wave. Contrary to our expectations, crayfish performance decreased in the long heat wave, suggesting that Mediterranean summer heat waves may have negative effects on P. clarkii and that they are unlikely to boost its populations in this region. Although uncertain, it is possible that the greater assimilation of the plant diet resulted from changes in crayfish feeding preferences, raising the hypotheses that i heat waves may change the predominant impacts of this keystone species and ii that by altering species' trophic niches, climate change may alter the main impacts of invasive alien species.

COMPARISON AMONG PRE-GELATINIZED STARCHES OF DIFFERENT BOTANICAL ORIGINS USED IN NOBLE CRAYFISH ASTACUS ASTACUS DIETS

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D’AGARO E.

2006-01-01

Full Text Available The objective of the present experiment was to compare the biological value and the binding functionality of four pre-gelatinized starches (wheat, diet 1; waxy maize, diet 2; maize, diet 3 and potato, diet 4 used in crayfish diets. 360 juvenile of A. astacus (initial b.w.: 0.70 ± 0.15 g were cultured in 12 tanks for 43d. Growth performance were significantly higher in crayfish fed diets containing wheat and waxy maize compared to those containing maize and potato pre-gelatinized starches. Disintegration in water and shear force tests of diets confirmed the superior binding capability of pre-gelatinized starches obtained from wheat and waxy maize. These results suggest that the pregelatinized wheat and waxy maize starches are the best choice for the production of diets for the noble crayfish.

Conservation status of crayfishes of the United States and Canada

Science.gov (United States)

Christopher A. Taylor; Melvin L. Warren; J. F. Fitzpatrick; Horton H. Hobbs; Raymond F. Jezerinac; William L. Pflieger; Henry W. Robinson

1996-01-01

The American Fisheries Society (AFS) Endangered Species Committee herein provides a list of all crayfishes (families and Cambaridae) in the United States and Canada that includes state provincial distributions; a comprehensive review of the conservation status of all taxa; and references on biology, conservation, and...

Potential impacts of alien freshwater crayfish in South Africa | de ...

African Journals Online (AJOL)

The habitat preferences and life history characteristics of four alien species of freshwater crayfish (Cherax tenuimanus, C. destructor, C. quadricarinatus and Procambarus clarkii) are reviewed. The potential impact of these species on South African freshwater ecosystems is assessed and the desirability of allowing their ...

Experiments on Automatic Recognition of Nonnative Arabic Speech

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Douglas O'Shaughnessy

2008-05-01

Full Text Available The automatic recognition of foreign-accented Arabic speech is a challenging task since it involves a large number of nonnative accents. As well, the nonnative speech data available for training are generally insufficient. Moreover, as compared to other languages, the Arabic language has sparked a relatively small number of research efforts. In this paper, we are concerned with the problem of nonnative speech in a speaker independent, large-vocabulary speech recognition system for modern standard Arabic (MSA. We analyze some major differences at the phonetic level in order to determine which phonemes have a significant part in the recognition performance for both native and nonnative speakers. Special attention is given to specific Arabic phonemes. The performance of an HMM-based Arabic speech recognition system is analyzed with respect to speaker gender and its native origin. The WestPoint modern standard Arabic database from the language data consortium (LDC and the hidden Markov Model Toolkit (HTK are used throughout all experiments. Our study shows that the best performance in the overall phoneme recognition is obtained when nonnative speakers are involved in both training and testing phases. This is not the case when a language model and phonetic lattice networks are incorporated in the system. At the phonetic level, the results show that female nonnative speakers perform better than nonnative male speakers, and that emphatic phonemes yield a significant decrease in performance when they are uttered by both male and female nonnative speakers.

Experiments on Automatic Recognition of Nonnative Arabic Speech

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Selouani Sid-Ahmed

2008-01-01

Full Text Available The automatic recognition of foreign-accented Arabic speech is a challenging task since it involves a large number of nonnative accents. As well, the nonnative speech data available for training are generally insufficient. Moreover, as compared to other languages, the Arabic language has sparked a relatively small number of research efforts. In this paper, we are concerned with the problem of nonnative speech in a speaker independent, large-vocabulary speech recognition system for modern standard Arabic (MSA. We analyze some major differences at the phonetic level in order to determine which phonemes have a significant part in the recognition performance for both native and nonnative speakers. Special attention is given to specific Arabic phonemes. The performance of an HMM-based Arabic speech recognition system is analyzed with respect to speaker gender and its native origin. The WestPoint modern standard Arabic database from the language data consortium (LDC and the hidden Markov Model Toolkit (HTK are used throughout all experiments. Our study shows that the best performance in the overall phoneme recognition is obtained when nonnative speakers are involved in both training and testing phases. This is not the case when a language model and phonetic lattice networks are incorporated in the system. At the phonetic level, the results show that female nonnative speakers perform better than nonnative male speakers, and that emphatic phonemes yield a significant decrease in performance when they are uttered by both male and female nonnative speakers.

Fluoride bioaccumulation and toxic effects on the survival and behavior of the endangered white-clawed crayfish Austropotamobius pallipes (Lereboullet).

Science.gov (United States)

Aguirre-Sierra, Arantxa; Alonso, Alvaro; Camargo, Julio A

2013-08-01

Laboratory experiments were performed to examine the toxic effects of fluoride (F(-)) on the survival and behavior of white-clawed crayfish (Austropotamobius pallipes). Body fluoride contents (bioaccumulation) of test crayfish were also examined. No significant differences between male and female crayfish regarding mortality, escape (tail-flip) response, and fluoride bioaccumulation were detected. For mortality, 48-, 72-, 96-, 120-, 144-, 168-, and 192-h median lethal concentrations (LC50) were estimated to be 93.0, 55.3, 42.7, 36.5, 32.9, 30.6, and 28.9 mg F(-)/l, respectively. For the escape response, 48-, 72-, 96-, 120-, 144-, 168- and 192-h median effective concentrations (EC50) were estimated to be 18.4, 11.1, 8.6, 7.4, 6.7, 6.2 and 5.9 mg F(-)/l, respectively. Average food consumption in test crayfish tended to decrease with increasing water fluoride concentration with a 192-h lowest-observed effect concentration of 10.7 mg F(-)/l. These results indicate that the escape response was the most sensitive end point to fluoride toxicity followed by food consumption and mortality. Fluoride bioaccumulation in test crayfish increased with increasing water fluoride concentration and exposure time. The exoskeleton accumulated more fluoride than muscle. A comparison of the obtained results with previous data for other freshwater invertebrates shows that white-clawed crayfish are relatively tolerant to fluoride toxicity. We conclude that fluoride pollution in freshwater ecosystems should not be viewed as an important risk factor contributing to the catastrophic decrease of A. pallipes in many European countries. Our results indicate that fluoride bioaccumulation in A. pallipes might be used as a bioindicator of fluoride pollution in freshwater ecosystems where it is present.

MANAGEMENT OF THE WHITE-CLAWED CRAYFISH (AUSTROPOTAMOBIUS PALLIPES IN WESTERN FRANCE: ABIOTIC AND BIOTIC FACTORS STUDY

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TROUILHE M. C.

2003-04-01

Full Text Available In France, the distribution of the white-clawed crayfish, Austropotamobius pallipes (Lereboullet, 1858, is restricted, fragmented and mainly located in headwaters. To preserve this indigenous species, it is necessary to characterize its ecological requirements (water and habitat quality. With this aim in view, a two-year study is being conducted in the Deux-Sèvres department (Western France since November 2002. Nine brooks from four different catchments are monitored regularly; eight of the nine brooks harbour whiteclawed crayfish populations. Two sampling sites are surveyed per brook, the first being where the crayfish population is located and the second 2 to 3 km downstream. Physicochemical parameters (18 are measured twice monthly and biotic factors are estimated twice yearly. In this study, the I.B.G.N. (Indice Biologique Global Normalisé protocol based on the determination of macroinvertebrates was used as a biotic index of biological water quality. Results of this preliminary study on two brooks (Thouet and Verdonnière show that physico-chemical and biological data considered separately do not provide reliable information about A. pallipes ecological requirements. However, the use of multivariate analyses (Principal Component Analysis to combine abiotic and biotic factors highlights a good correlation between these parameters. Organic matter appears to be a better discriminating factor than mineral matter affecting presence or absence of the whiteclawed crayfish.

Are eavesdroppers multimodal? Sensory exploitation of flo-ral signals by a non-native cockroach Blatta orientalis

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Rodrigo C. VERGARA, Alejandra TORRES-ARANEDA, Diego A. VILLAGRA, Robert A. RAGUSO, Mary T. K. ARROYO, Cristian A. VILLAGRA

2011-04-01

Full Text Available The study of multi-modal communication has only recently been extended to innate and learned interactions between flowers and their animal visitors, and usually only to pollinators. Here we studied the relevance of floral scent and visual display of a night blooming, putatively hawkmoth-pollinated plant Oenothera acaulis (Onagraceae in the attraction of non-native cockroaches Blatta orientalis (Blattodea: Blattidae, which function as facultative floral larcenists in coastal habitats of central Chile. We experimentally decoupled visual (corolla and olfactory (fragrance stimuli by presenting paper corollas and green mesh bags, with or without a freshly-picked natural flower inside. We then contrasted the behavioral responses of roaches in these treatments with those to the natural combination of traits in actual flowers and their respective control treatments, measuring the roaches’ frequency of first visits, mean and total residence time spent in each treatment. The roaches primarily used olfactory cues when approaching O. acaulis flowers at two biologically relevant spatial scales. In addition, the presence of conspecific roaches had a strong influence on recruitment to the experimental arena, increasing the statistical differences among treatments. Our results suggest a primacy of floral fragrance over visual stimuli in the foraging responses of B. orientalis. Olfactory cues were necessary and sufficient to attract the roaches, and the visual cues presented in our manipulations only marginally increased their attraction within a 20 cm diameter of the stimulus. The full spectrum of floral visitation behavior was not elicited by the artificial flowers, suggesting the need for additional tactile or contact chemosensory stimuli not provided by paper. Although the nitrogenous scent compounds that we found in O. acaulis flowers are almost exclusively found in hawkmoth-pollinated flowers, the attractiveness of these compounds to a non-native

Laboratory and field assessment of uranium trophic transfer efficiency in the crayfish Orconectes limosus fed the bivalve C. fluminea

International Nuclear Information System (INIS)

Simon, Olivier; Garnier-Laplace, Jacqueline

2005-01-01

At present, ecotoxicological information regarding the impact of natural uranium (U) on freshwater ecosystems via the trophic contamination route is scarce. We generated an experimental trophic food chain involving the prey species, Corbicula fluminea, and a predator, Orconectes limosus, for a 10-day and a 30-day feeding periods (food ration: one whole soft body/day/crayfish). We studied the efficiency of U trophic transfer and the distribution of U in the predator. During the test, we varied the quantity of dietary U (from beforehand contaminated bivalves at concentrations ranging from 0.9 ± 0.1 to 20.2 ± 9 μg/g fw provided to each crayfish over the 10 days) applying a daily feeding rate equal to 3.9 ± 0.8% fw. The efficiency of U trophic transfer from clams to crayfish varied between 1 and 13% depending on the prey exposure modalities. Accumulation of U was observed in the digestive gland but also in gills, in the muscle, and in the molt of the crayfish after trophic exposure treatments. Under high-level exposure conditions, the digestive gland was the main target-organ, however a significant accumulation was also observed in the stomach. With regard to low levels of trophic exposure, accumulation of U in gills, in the stomach, and in the digestive gland was of the same order of magnitude. Longer exposure period which incorporated a crayfish molt, resulted in a decrease of trophic transfer ratio and a modified U tissue distribution

DISTRIBUTION, RECENT MORTALITIES AND CONSERVATION MEASURES OF CRAYFISH IN HELLENIC FRESH WATERS

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KOUTRAKIS E.

2007-04-01

Full Text Available Freshwater crayfish are found in 20 out of 53 Prefectures of Greece (38% and they form isolated populations in relatively pristine water bodies. Three indigenous crayfish species (ICS occur in Greek waters: Astacus astacus, Astacus leptodactylus and Austropotamobius torrentium, as well as one non-indigenous crayfish species (NICS Pacifastacus leniusculus. Greece represents probably the most southern natural distribution limit for A. astacus and A. torrentium in the world. Concerning NICS, P. leniusculus was imported, at least in two cases, from Sweden and Germany during the early and late 1980’s respectively, in order to replace A. astacus stocks impoverished by human activities. Recently, Cherax quadricarinatus specimens have been seen in a restaurant’s aquarium and pet shop, raising fears about uncontrolled imports of alien pet species. During our 2004-2005 survey, we found that P. leniusculus established not only a thriving population in the artificial Lake Agra (Region of Central Macedonia, but also they co-occur with A. torrentium there. It is also suspected that A. astacus may co-occur there with these two species, as three large male specimens of A. astacus were caught in a creek close to the lake. Concerning A. leptodactylus, there are three sets of preserved samples from the River Evros (state border with Turkey in Thrace today, dated back to the 19th century, but no recent information about occurrence was available. But the accidental catch of six specimens of A. leptodactylus during May 2005 in that river re-documented the occurrence of the species. Finally, a deep-dwelling A. torrentium population with bluish legs was found to live in depths up to 7,800 meters inside the Aggitis Cave in northeastern Greece. There is a lot of work to be done on geographic distribution, population dynamics, genetics, reproduction, nutrition, diseases, and farming of crayfish species in Greece. Moreover, several actions should be undertaken to

Habitat and co-occurrence of native and invasive crayfish in the Pacific Northwest, USA

Science.gov (United States)

Pearl, Christopher A.; Adams, Michael J.; McCreary, Brome

2013-01-01

Biological invasions can have dramatic effects on freshwater ecosystems and introduced crayfish can be particularly impacting. We document crayfish distribution in three large hydrographic basins (Rogue, Umpqua, Willamette/Columbia) in the Pacific Northwest USA. We used occupancy analyses to investigate habitat relationships and evidence for displacement of native Pacifastacus leniusculus (Dana, 1852) by two invaders. We found invasive Procambarus clarkii (Girard, 1852), in 51 of 283 sites and in all three hydrographic basins. We found invasive Orconectes n. neglectus (Faxon, 1885) at 68% of sites in the Rogue basin and provide first documentation of their broad distribution in the Umpqua basin. We found P. clarkii in both lentic and lotic habitats, and it was positively associated with manmade sites. P. leniusculus was positively associated with lotic habitats and negatively related to manmade sites. In the Rogue and Umpqua basins, O. n. neglectus and P. leniusculus were similar in their habitat associations. We did not find a negative relationship in site occupancy between O. n. neglectus and P. leniusculus. Our data suggest that P. clarkii has potential to locally displace P. leniusculus. There is still time for preventive measures to limit the spread of the invasive crayfish in this region.

Crayfish Behavior: Observing Arthropods to Learn about Science & Scientific Inquiry

Science.gov (United States)

Rop, Charles J.

2010-01-01

This is a set of animal behavior investigations in which students will practice scientific inquiry as they observe crayfish, ask questions, and discuss territoriality, social interactions, and other behaviors. In doing this, they hone their skills of observation, learn to record and analyze data, control for variables, write hypotheses, make…

Non-native plant invasions of United States National parks

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Allen, J.A.; Brown, C.S.; Stohlgren, T.J.

2009-01-01

The United States National Park Service was created to protect and make accessible to the public the nation's most precious natural resources and cultural features for present and future generations. However, this heritage is threatened by the invasion of non-native plants, animals, and pathogens. To evaluate the scope of invasions, the USNPS has inventoried non-native plant species in the 216 parks that have significant natural resources, documenting the identity of non-native species. We investigated relationships among non-native plant species richness, the number of threatened and endangered plant species, native species richness, latitude, elevation, park area and park corridors and vectors. Parks with many threatened and endangered plants and high native plant species richness also had high non-native plant species richness. Non-native plant species richness was correlated with number of visitors and kilometers of backcountry trails and rivers. In addition, this work reveals patterns that can be further explored empirically to understand the underlying mechanisms. ?? Springer Science+Business Media B.V. 2008.

Antibacterial properties of extracts of Solidago canadensis and their potential use as dietary supplements in red swamp crayfish (Procambarus clarkii

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Manhong YE,Lei ZHANG,Jiaqi GE,Haifeng SUN,Jingjing NI,Shengmei YANG,Wanhong WEI

2015-12-01

Full Text Available Canadian goldenrod (Solidago canadensis is one of the most destructive invasive weeds in South-eastern China. To evaluate its potential application as dietary supplement in red swamp crayfish (Procambarus clarkii, the antibacterial properties of aqueous and ethanol extracts of this plant against three major pathogenic bacteria in crayfish aquaculture were examined. Inhibition zone tests and determination of minimum inhibitory concentration revealed that the extracts had lower antibacterial activity than extracts from two traditional medicinal plants that possess antibacterial properties, garlic (Allium sativum and cortex phellodendri (Phellodendron chinense. However, they did exhibit greater antibacterial effects than extracts from another widely used medicinal plant, Sophora flavescens, and an aquatic weed, Alternanthera philoxeroides. Aqueous extracts of Canadian goldenrod gave greater inhibition than the ethanol extracts. Crayfish fed a diet with 2% these aqueous extracts exhibited significantly higher enzyme activity of alkaline phosphatase, catalase and phenoloxidase (P<0.05. Based on the results of this study, we conclude that aqueous extracts of Canadian goldenrod are highly promising for the development of new dietary supplement for use in crayfish aquaculture.

Effects of chronic cocaine, morphine and methamphetamine on the mobility, immobility and stereotyped behaviors in crayfish.

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Imeh-Nathaniel, Adebobola; Rincon, Natalia; Orfanakos, Vasiliki Bessie; Brechtel, Leanne; Wormack, Leah; Richardson, Erika; Huber, Robert; Nathaniel, Thomas I

2017-08-14

The worth of crayfish as a model system for studies of addiction was not previously recognized because a drug-reward phenomenon had not been documented in this model system. In our previous experiments, we demonstrate that the crayfish natural reward pathways are sensitive to human drugs of abuse. This finding supports crayfish as a suitable model to characterize specific behaviors that are relevant in drug addiction research, and the current study builds on our previous findings. The aim of the present study was to investigate unconditioned neurobehavioral effects of repeated treatment regimens using cocaine, morphine, and methamphetamine for three consecutive days. We analyzed mobility, immobility and characterized stereotypic behaviors following intracardial infusions of 2.0μg/g or 10.0μg/g doses of cocaine, morphine, and methamphetamine for three days. The results showed that systemic cocaine, morphine, and methamphetamine increased mobility at a low dose of 2.0μg/g more effectively than a high dose of 10.0μg/g, while simultaneously showing that the high dose exerted a more prominent effect in increasing immobility. Moreover, systemic cocaine, morphine, and methamphetamine injections have discerning effects towards a group of defined unconditioned stereotyped behavioral patterns associated with each drug, rather than a shared universal behavioral effect. These findings provide insight into the behavioral and pharmacological basis responsible for the unconditioned effects of these drugs in crayfish. Copyright © 2017. Published by Elsevier B.V.

New distributional records of the stygobitic crayfish Cambarus cryptodytes (Decapoda: Cambaridae) in the Floridan Aquifer System of southwestern Georgia

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Fenolio, Dante B.; Niemiller, Matthew L.; Gluesenkamp, Andrew G.; Mckee, Anna; Taylor, Steven J.

2017-01-01

Cambarus cryptodytes (Dougherty Plain Cave Crayfish) is an obligate inhabitant of groundwater habitats (i.e., a stygobiont) with troglomorphic adaptations in the Floridan aquifer system of southwestern Georgia and adjacent Florida panhandle, particularly in the Dougherty Plain and Marianna Lowlands. Documented occurrences of Dougherty Plain Cave Crayfish are spatially distributed as 2 primary clusters separated by a region where few caves and springs have been documented; however, the paucity of humanly accessible karst features in this intermediate region has inhibited investigation of the species' distribution. To work around this constraint, we employed bottle traps to sample for Dougherty Plain Cave Crayfish and other groundwater fauna in 18 groundwater-monitoring wells that access the Floridan aquifer system in 10 counties in southwestern Georgia. We captured 32 Dougherty Plain Cave Crayfish in 9 wells in 8 counties between September 2014 and August 2015. We detected crayfish at depths ranging from 17.9 m to 40.6 m, and established new county records for Early, Miller, Mitchell, and Seminole counties in Georgia, increasing the number of occurrences in Georgia from 8 to 17 sites. In addition, a new US Geological Survey (USGS) Hydrologic Unit Code 8 (HUC8) watershed record was established for the Spring Creek watershed. These new records fill in the distribution gap between the 2 previously known clusters in Georgia and Jackson County, FL. Furthermore, this study demonstrates that deployment of bottle traps in groundwater-monitoring wells can be an effective approach to presence—absence surveys of stygobionts, especially in areas where surface access to groundwater is limited.

Neuromodulation of activity-dependent synaptic enhancement at crayfish neuromuscular junction.

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Qian, S M; Delaney, K R

1997-10-17

Action potential-evoked transmitter release is enhanced for many seconds after moderate-frequency stimulation (e.g. 15 Hz for 30 s) at the excitor motorneuron synapse of the crayfish dactyl opener muscle. Beginning about 1.5 s after a train, activity-dependent synaptic enhancement (ADSE) is dominated by a process termed augmentation (G.D. Bittner, D.A. Baxter, Synaptic plasticity at crayfish neuromuscular junctions: facilitation and augmentation, Synapse 7 (1991) 235-243'[4]; K.L. Magleby, Short-term changes in synaptic efficacy, in: G.M. Edelman, L.E. Gall, C.W. Maxwell (Eds.), Synaptic Function, John Wiley and Sons, New York, 1987, pp. 21-56; K.L. Magleby; J.E. Zengel, Augmentation: a process that acts to increase transmitter release at the frog neuromuscular junction, J. Physiol. (Lond.) 257 (1976) 449-470) which decays approximately exponentially with a time constant of about 10 s at 16 degrees C, reflecting the removal of Ca2+ which accumulates during the train in presynaptic terminals (K.R. Delaney, D.W. Tank, R.S. Zucker, Serotonin-mediated enhancement of transmission at crayfish neuromuscular junction is independent of changes in calcium, J. Neurosci. 11 (1991) 2631-2643). Serotonin (5-HT, 1 microM) increases evoked and spontaneous transmitter release several-fold (D. Dixon, H.L. Atwood, Crayfish motor nerve terminal's response to serotonin examined by intracellular microelectrode, J. Neurobiol. 16 (1985) 409-424; J. Dudel, Modulation of quantal synaptic release by serotonin and forskolin in crayfish motor nerve terminals, in: Modulation of Synaptic Transmission and Plasticity in Nervous Systems, G. Hertting, H.-C. Spatz (Eds.), Springer-Verlag, Berlin, 1988; S. Glusman, E.A. Kravitz. The action of serotonin on excitatory nerve terminals in lobster nerve-muscle preparations, J. Physiol. (Lond.) 325 (1982) 223-241). We found that ADSE persists about 2-3 times longer after moderate-frequency presynaptic stimulation in the presence of 5-HT. This slowing of the

Stress reaction in crayfish: chlorides help to withstand stress in high nitrite concentration conditions – preliminary study

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Kozák P.

2011-06-01

Full Text Available A non-invasive method of recording cardiac activity (heart rate – HR and stress reaction (stress index – SI was used to understand the immediate and ongoing stress reaction of crayfish to the chemical stimuli. This method detects changes in the shape and amplitude parameters of the response to the stress factors, which characterized the crayfish functional state. Experimental animals (Astacus leptodactylus were divided to the two groups with (400 mg·L-1 Cl− and without added chlorides and then exposed to a stepwise increased level of nitrite to the final (sublethal-lethal concentration of 60 mg·L-1 N-NO\\hbox{$_{2}^{-}$}−2 within 24 hours. The course of crayfish reaction was evident and provided information about their reaction to the sublethal-lethal concentration over time. As expected, a less prominent stress reaction was detected in the group with chlorides. The non-invasive method successfully evaluated the sensing of chemical stimuli in water through HR and SI changes.

Evaluation of different marking methods for spiny-cheek crayfish (Orconectes limosus

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Buřič M.

2008-10-01

Full Text Available Different methods of marking were evaluated for Orconectes limosus (CL = carapace length, 12–37 mm under laboratory conditions: the use of passive integrated transponders, visible implant elastomers, visible implant alphanumeric tags, and cauterization. High survival (> 90% was obtained with all methods tested. Tag retention and readability were evaluated immediately after marking, before and after ecdysis, with moult increments and number of moults been recorded. Marking using cauterization negatively affects the percent moult increment (PMI of crayfish. The average PMI of 15 ± 0.88% did not differ between males (15 ± 1.41 mm and females (15 ± 1.12 mm. It was found that PMI gradually decreased with an increase in CL. Sixty-one moults were observed, with 12 crayfish (6 juveniles and 6 adults presenting two moults. Time between moults varied from 3 to 7 weeks. CL was increased with over 28 ± 2.68% due to two moults. Three females moulted twice after successful hatching and carrying of juveniles.

The effect on recognition memory of noise cancelling headphones in a noisy environment with native and nonnative speakers

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Brett R C Molesworth

2014-01-01

Full Text Available Noise has the potential to impair cognitive performance. For nonnative speakers, the effect of noise on performance is more severe than their native counterparts. What remains unknown is the effectiveness of countermeasures such as noise attenuating devices in such circumstances. Therefore, the main aim of the present research was to examine the effectiveness of active noise attenuating countermeasures in the presence of simulated aircraft noise for both native and nonnative English speakers. Thirty-two participants, half native English speakers and half native German speakers completed four recognition (cued recall tasks presented in English under four different audio conditions, all in the presence of simulated aircraft noise. The results of the research indicated that in simulated aircraft noise at 65 dB(A, performance of nonnative English speakers was poorer than for native English speakers. The beneficial effects of noise cancelling headphones in improving the signal to noise ratio led to an improved performance for nonnative speakers. These results have particular importance for organizations operating in a safety-critical environment such as aviation.

Effects of dietary propolis on the number and size of pleopadal egg, oxidative stress and antioxidant status of freshwater crayfish (Astacus leptodactylus Eschscholtz).

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Mişe Yonar, Serpil; Köprücü, Kenan; Yonar, Muhammet Enis; Silici, Sibel

2017-09-01

Four different crayfish diets; control, E1, E2 and E3, respectively containing 0, 1, 2 and 4% propolis, were tested to determine the effects of dietary propolis on the number and size of pleopadal egg, and malondialdehyde (MDA) level, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities in the freshwater crayfish (Astacus leptodactylus). The crayfish were kept at 9.6±5.3°C water temperature and fed three times daily during a six month period The pleopodal egg number (from 7 to 9) produced per gram of the body weight and total pleopodal egg number (from 201 to 263) significantly increased (Pegg size (from 3.22mm to 2.76mm). MDA level significantly (Pegg. The dietary propolis improves reproductive efficiency in the crayfish and decreases the oxidative stress under controlled hatchery conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

Differences found in the macroinvertebrate community composition in the presence or absence of the invasive alien crayfish, Orconectes hylas

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Freeland-Riggert, Brandye T.; Cairns, Stefan H.; Poulton, Barry C.; Riggert, Chris M.

2016-01-01

Introductions of alien species into aquatic ecosystems have been well documented, including invasions of crayfish species; however, little is known about the effects of these introductions on macroinvertebrate communities. The woodland crayfish (Orconectes hylas (Faxon)) has been introduced into the St. Francis River watershed in southeast Missouri and has displaced populations of native crayfish. The effects of O. hylas on macroinvertebrate community composition were investigated in a fourth-order Ozark stream at two locations, one with the presence of O. hylas and one without. Significant differences between sites and across four sampling periods and two habitats were found in five categories of benthic macroinvertebrate metrics: species richness, percent/composition, dominance/diversity, functional feeding groups, and biotic indices. In most seasons and habitat combinations, the invaded site had significantly higher relative abundance of riffle beetles (Coleoptera: Elmidae), and significantly lower Missouri biotic index values, total taxa richness, and both richness and relative abundance of midges (Diptera: Chironomidae). Overall study results indicate that some macroinvertebrate community differences due to the O. hylas invasion were not consistent between seasons and habitats, suggesting that further research on spatial and temporal habitat use and feeding ecology of Ozark crayfish species is needed to improve our understanding of the effects of these invasions on aquatic communities.

Small nonnative fishes as predators of larval razorback suckers

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Carpenter, J.; Mueller, G.A.

2008-01-01

The razorback sucker (Xyrauchen texanus), an endangered big-river fish of the Colorado River basin, has demonstrated no sustainable recruitment in 4 decades, despite presence of spawning adults and larvae. Lack of adequate recruitment has been attributed to several factors, including predation by nonnative fishes. Substantial funding and effort has been expended on mechanically removing nonnative game fishes, typically targeting large predators. As a result, abundance of larger predators has declined, but the abundance of small nonnative fishes has increased in some areas. We conducted laboratory experiments to determine if small nonnative fishes would consume larval razorback suckers. We tested adults of three small species (threadfin shad, Dorosoma petenense; red shiner, Cyprinella lutrensis; fathead minnow, Pimephales promelas) and juveniles of six larger species (common carp, Cyprinus carpio; yellow bullhead, Ameiurus natalis; channel catfish, Ictalurus punctatus; rainbow trout, Oncorhynchus mykiss; green sunfish, Lepomis cyanellus; bluegill, L. macrochirus). These nonnative fishes span a broad ecological range and are abundant within the historical range of the razorback sucker. All nine species fed on larval razorback suckers (total length, 9-16 mm). Our results suggest that predation by small nonnative fishes could be responsible for limiting recovery of this endangered species.

Neighbour tolerance, not suppression, provides competitive advantage to non-native plants.

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Golivets, Marina; Wallin, Kimberly F

2018-05-01

High competitive ability has often been invoked as a key determinant of invasion success and ecological impacts of non-native plants. Yet our understanding of the strategies that non-natives use to gain competitive dominance remains limited. Particularly, it remains unknown whether the two non-mutually exclusive competitive strategies, neighbour suppression and neighbour tolerance, are equally important for the competitive advantage of non-native plants. Here, we analyse data from 192 peer-reviewed studies on pairwise plant competition within a Bayesian multilevel meta-analytic framework and show that non-native plants outperform their native counterparts due to high tolerance of competition, as opposed to strong suppressive ability. Competitive tolerance ability of non-native plants was driven by neighbour's origin and was expressed in response to a heterospecific native but not heterospecific non-native neighbour. In contrast to natives, non-native species were not more suppressed by hetero- vs. conspecific neighbours, which was partially due to higher intensity of intraspecific competition among non-natives. Heterogeneity in the data was primarily associated with methodological differences among studies and not with phylogenetic relatedness among species. Altogether, our synthesis demonstrates that non-native plants are competitively distinct from native plants and challenges the common notion that neighbour suppression is the primary strategy for plant invasion success. © 2018 John Wiley & Sons Ltd/CNRS.

Co-occurring nonnative woody shrubs have additive and non-additive soil legacies.

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Kuebbing, Sara E; Patterson, Courtney M; Classen, Aimée T; Simberloff, Daniel

2016-09-01

To maximize limited conservation funds and prioritize management projects that are likely to succeed, accurate assessment of invasive nonnative species impacts is essential. A common challenge to prioritization is a limited knowledge of the difference between the impacts of a single nonnative species compared to the impacts of nonnative species when they co-occur, and in particular predicting when impacts of co-occurring nonnative species will be non-additive. Understanding non-additivity is important for management decisions because the management of only one co-occurring invader will not necessarily lead to a predictable reduction in the impact or growth of the other nonnative plant. Nonnative plants are frequently associated with changes in soil biotic and abiotic characteristics, which lead to plant-soil interactions that influence the performance of other species grown in those soils. Whether co-occurring nonnative plants alter soil properties additively or non-additively relative to their effects on soils when they grow in monoculture is rarely addressed. We use a greenhouse plant-soil feedback experiment to test for non-additive soil impacts of two common invasive nonnative woody shrubs, Lonicera maackii and Ligustrum sinense, in deciduous forests of the southeastern United States. We measured the performance of each nonnative shrub, a native herbaceous community, and a nonnative woody vine in soils conditioned by each shrub singly or together in polyculture. Soils conditioned by both nonnative shrubs had non-additive impacts on native and nonnative performance. Root mass of the native herbaceous community was 1.5 times lower and the root mass of the nonnative L. sinense was 1.8 times higher in soils conditioned by both L. maackii and L. sinense than expected based upon growth in soils conditioned by either shrub singly. This result indicates that when these two nonnative shrubs co-occur, their influence on soils disproportionally favors persistence

Co-occurring nonnative woody shrubs have additive and non-additive soil legacies

DEFF Research Database (Denmark)

Kuebbing, Sara E.; Patterson, Courtney M.; Classen, Aimee Taylor

2016-01-01

shrubs, Lonicera maackii and Ligustrum sinense, in deciduous forests of the southeastern United States. We measured the performance of each nonnative shrub, a native herbaceous community, and a nonnative woody vine in soils conditioned by each shrub singly or together in polyculture. Soils conditioned...... by both nonnative shrubs had non-additive impacts on native and nonnative performance. Root mass of the native herbaceous community was 1.5 times lower and the root mass of the nonnative L. sinense was 1.8 times higher in soils conditioned by both L. maackii and L. sinense than expected based upon growth...... in soils conditioned by either shrub singly. This result indicates that when these two nonnative shrubs co-occur, their influence on soils disproportionally favors persistence of the nonnative L. sinense relative to this native herbaceous community, and could provide an explanation of why native species...

Predicting probability of occurrence and factors affecting distribution and abundance of three Ozark endemic crayfish species at multiple spatial scales

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Nolen, Matthew S.; Magoulick, Daniel D.; DiStefano, Robert J.; Imhoff, Emily M.; Wagner, Brian K.

2014-01-01

Crayfishes and other freshwater aquatic fauna are particularly at risk globally due to anthropogenic demand, manipulation and exploitation of freshwater resources and yet are often understudied. The Ozark faunal region of Missouri and Arkansas harbours a high level of aquatic biological diversity, especially in regard to endemic crayfishes. Three such endemics, Orconectes eupunctus,Orconectes marchandi and Cambarus hubbsi, are threatened by limited natural distribution and the invasions of Orconectes neglectus.

CONFIRMATION OF OCCURRENCE OF THE NARROW-CLAWED CRAYFISH ? STACUS LEPTODACTYLUS ESCHSCHOLTZ, 1823 IN THE RIVER EVROS IN GREECE

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PERDIKARIS C.

2007-04-01

Full Text Available The narrow-clawed crayfish Astacus leptodactylus Eschscholtz, 1823, is widely distributed in eastern European and western Asian countries. However, species presence in Greece was documented only by limited museum conserved specimens dating back to 1893. Recently (May 2005 several crayfish were captured in the Evros River (close to city of Didimotiho and these were identified as A. leptodactylus. The present work confirms the presence of A. leptodactylus in the Evros River still hundred and twelve years later and introduces the possibility of A. leptodactylus being indigenous to Greece.

Negative, neutral, and positive interactions among nonnative plants: patterns, processes, and management implications.

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Kuebbing, Sara E; Nuñez, Martin A

2015-02-01

The movement of species is one of the most pervasive forms of global change, and few ecosystems remain uninvaded by nonnative species. Studying species interactions is crucial for understanding their distribution and abundance, particularly for nonnative species because interactions may influence the probability of invasion and consequent ecological impact. Interactions among nonnatives are relatively understudied, though the likelihood of nonnative species co-occurrence is high. We quantify and describe the types of interactions among nonnative plants and determine what factors affect interaction outcomes for ecosystems globally. We reviewed 65 studies comprising 201 observations and recorded the interaction type, traits of the interacting species, and study characteristics. We conducted a census of interaction types and a meta-analysis of experiments that tested nonnative competition intensity. Both methods showed that negative and neutral interactions prevailed, and a number of studies reported that the removal of a dominant nonnative led to competitive release of other nonnatives. Positive interactions were less frequently reported and positive mean effect sizes were rare, but the plant characteristics nitrogen fixation, life cycle (annual or perennial), and functional group significantly influenced positive interactions. Positive interactions were three times more frequent when a neighboring nonnative was a nitrogen fixer and 3.5 times lower when a neighboring nonnative was an annual. Woody plants were two or four times more likely to have positive interactions relative to grasses or herbs, respectively. The prevalence of negative interactions suggests that managers should prepare for reinvasion of sites when treating dominant nonnatives. Though positive interactions were infrequent, managers may be able to anticipate positive interactions among nonnatives based upon traits of the co-occurring invaders. Predicting positive nonnative interactions is an

Vulnerability of freshwater native biodiversity to non-native ...

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Background/Question/Methods Non-native species pose one of the greatest threats to native biodiversity. The literature provides plentiful empirical and anecdotal evidence of this phenomenon; however, such evidence is limited to local or regional scales. Employing geospatial analyses, we investigate the potential threat of non-native species to threatened and endangered aquatic animal taxa inhabiting unprotected areas across the continental US. We compiled distribution information from existing publicly available databases at the watershed scale (12-digit hydrologic unit code). We mapped non-native aquatic plant and animal species richness, and an index of cumulative invasion pressure, which weights non-native richness by the time since invasion of each species. These distributions were compared to the distributions of native aquatic taxa (fish, amphibians, mollusks, and decapods) from the International Union for the Conservation of Nature (IUCN) database. We mapped the proportion of species listed by IUCN as threatened and endangered, and a species rarity index per watershed. An overlay analysis identified watersheds experiencing high pressure from non-native species and also containing high proportions of threatened and endangered species or exhibiting high species rarity. Conservation priorities were identified by generating priority indices from these overlays and mapping them relative to the distribution of protected areas across the US. Results/Conclusion

Nonnative Fishes in the Upper Mississippi River System

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Irons, Kevin S.; DeLain, Steven A.; Gittinger, Eric; Ickes, Brian S.; Kolar, Cindy S.; Ostendort, David; Ratcliff, Eric N.; Benson, Amy J.; Irons, Kevin S.

2009-01-01

The introduction, spread, and establishment of nonnative species is widely regarded as a leading threat to aquatic biodiversity and consequently is ranked among the most serious environmental problems facing the United States today. This report presents information on nonnative fish species observed by the Long Term Resource Monitoring Program on the Upper Mississippi River System a nexus of North American freshwater fish diversity for the Nation. The Long Term Resource Monitoring Program, as part of the U.S. Army Corps of Engineers' Environmental Management Plan, is the Nation's largest river monitoring program and stands as the primary source of standardized ecological information on the Upper Mississippi River System. The Long Term Resource Monitoring Program has been monitoring fish communities in six study areas on the Upper Mississippi River System since 1989. During this period, more than 3.5 million individual fish, consisting of 139 species, have been collected. Although fish monitoring activities of the Long Term Resource Monitoring Program focus principally on entire fish communities, data collected by the Program are useful for detecting and monitoring the establishment and spread of nonnative fish species within the Upper Mississippi River System Basin. Sixteen taxa of nonnative fishes, or hybrids thereof, have been observed by the Long Term Resource Monitoring Program since 1989, and several species are presently expanding their distribution and increasing in abundance. For example, in one of the six study areas monitored by the Long Term Resource Monitoring Program, the number of established nonnative species has increased from two to eight species in less than 10 years. Furthermore, contributions of those eight species can account for up to 60 percent of the total annual catch and greater than 80 percent of the observed biomass. These observations are critical because the Upper Mississippi River System stands as a nationally significant pathway for

EVALUATION OF THE AMERICAN WATERWEED (ELODEA CANADENSIS MICHX. AS SUPPLEMENTAL FOOD FOR THE NOBLE CRAYFISH, ASTACUS ASTACUS

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D’AGARO E.

2004-01-01

Full Text Available We conducted a preliminary study to evaluate the capacity of summerling Astacus astacus to consume the American waterweed (Elodea canadensis Michx..under artificial rearing conditions. Summerling A. astacus (initial b.w.: 0.32 ± 0.02 g were cultured (50 crayfish/m2 in 600l tanks for 89 days. The experimental design was composed of three treatments as follows: control diet (D (crude protein: 40.9% DM; ether extract: 7.4% DM, elodea (E (crude protein: 25.8% DM; ether extract: 1.4% DM and control diet + elodea (D + E with three replicates per treatment. Temperature, dissolved oxygen, and other water parameters were measured weekly (T: 20.1°C; O2: 7.2 mg/l; pH: 7.5; N-NH4: 0.05 mg/l; N-NO2: 0.01 mg/l; N-NO3: 29.9 mg/l. The relative growth rate was significantly (P < 0.01 higher in treatment D + E (195% and D (143% than in E (65%. The reduced growth observed in crayfish fed elodea only can probably be due to the lower dietary lipid level of the plant respect to the standard crayfish requirements. At the end of the experiment, the survival rate of A. astacus was higher (P < 0.05 for the treatment D + E (87% and D (81%, compared to E (56%. Our results suggest that E. canadensis can be used as a non-expensive supplemental food in order to increase growth and survival in summerling noble crayfish. They also showed that A. astacus has the potential to consume this macrophyte in nature.

The Use of Fresh Cogongrass as Transportation Media with Level Dry System for Broodstock of Crayfish on Various Old Time

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Ferdinand Hukama Taqwa

2015-01-01

Full Text Available The research was to determine the effect of the use of fresh cogongrass as media packaging filler on survival rate of broodstock of crayfish that transported with level dry system for 24, 48, dan 72 hours which randomized completely design experiment. The research preparation were media preparation of pond water, preparation of filler material and preparation of experimental animal (3 days adaptation after arrived from producer and starvation for 24 hours. The major research were anestetion of broodstock of crayfish with direct sock of low temperature at 12oC for ±5 minutes, transportation experiment of broodstock with fresh cogongrass as material filler. The result showed that the use of fresh cogongrass on various old time of dry level system has a significantly different to time of recovery and survival rate of broodstock of crayfish after tranforted. The fastest time of recovery was 89.55 seconds for 24 hours transportation and significantly different with time of transportation for 48 hours and 72 hours. The survival rate after tranported the highest was 98.89% for 24 hours transportation and significantly different with time of transportation for 48 hours and 72 hours. This research showed that the use of fresh cogongrass as material packaging filler of dry level system was still effective until 48 hours.Keywords: afresh cogongrass, broodstock of crayfish, various old time transportation, level dry system

Comparative Ultrastructure and Carbohydrate Composition of Gastroliths from Astacidae, Cambaridae and Parastacidae Freshwater Crayfish (Crustacea, Decapoda

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Gérard Alcaraz

2012-12-01

Full Text Available Crustaceans have to cyclically replace their rigid exoskeleton in order to grow. Most of them harden this skeleton by a calcification process. Some decapods (land crabs, lobsters and crayfish elaborate calcium storage structures as a reservoir of calcium ions in their stomach wall, as so-called gastroliths. For a better understanding of the cyclic elaboration of these calcium deposits, we studied the ultrastructure of gastroliths from freshwater crayfish by using a combination of microscopic and physical techniques. Because sugars are also molecules putatively involved in the elaboration process of these biomineralizations, we also determined their carbohydrate composition. This study was performed in a comparative perspective on crayfish species belonging to the infra-order Astacidea (Decapoda, Malacostraca: three species from the Astacoidea superfamily and one species from the Parastacoidea superfamily. We observed that all the gastroliths exhibit a similar dense network of protein-chitin fibers, from macro- to nanoscale, within which calcium is precipitated as amorphous calcium carbonate. Nevertheless, they are not very similar at the molecular level, notably as regards their carbohydrate composition. Besides glucosamine, the basic carbohydrate component of chitin, we evidenced the presence of other sugars, some of which are species-specific like rhamnose and galacturonic acid whereas xylose and mannose could be linked to proteoglycan components.

Development of crayfish bio-based plastic materials processed by small-scale injection moulding.

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Felix, Manuel; Romero, Alberto; Cordobes, Felipe; Guerrero, Antonio

2015-03-15

Protein has been investigated as a source for biodegradable polymeric materials. This work evaluates the development of plastic materials based on crayfish and glycerol blends, processed by injection moulding, as a fully biodegradable alternative to conventional polymer-based plastics. The effect of different additives, namely sodium sulfite or bisulfite as reducing agents, urea as denaturing agent and L-cysteine as cross-linking agent, is also analysed. The incorporation of any additive always yields an increase in energy efficiency at the mixing stage, but its effect on the mechanical properties of the bioplastics is not so clear, and even dampened. The additive developing a greater effect is L-cysteine, showing higher Young's modulus values and exhibiting a remnant thermosetting potential. Thus, processing at higher temperature yields a remarkable increase in extensibility. This work illustrates the feasibility of crayfish-based green biodegradable plastics, thereby contributing to the search for potential value-added applications for this by-product. © 2014 Society of Chemical Industry.

Lexical exposure to native language dialects can improve non-native phonetic discrimination.

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Olmstead, Annie J; Viswanathan, Navin

2018-04-01

Nonnative phonetic learning is an area of great interest for language researchers, learners, and educators alike. In two studies, we examined whether nonnative phonetic discrimination of Hindi dental and retroflex stops can be improved by exposure to lexical items bearing the critical nonnative stops. We extend the lexical retuning paradigm of Norris, McQueen, and Cutler (Cognitive Psychology, 47, 204-238, 2003) by having naive American English (AE)-speaking participants perform a pretest-training-posttest procedure. They performed an AXB discrimination task with the Hindi retroflex and dental stops before and after transcribing naturally produced words from an Indian English speaker that either contained these tokens or not. Only those participants who heard words with the critical nonnative phones improved in their posttest discrimination. This finding suggests that exposure to nonnative phones in native lexical contexts supports learning of difficult nonnative phonetic discrimination.

A multigear protocol for sampling crayfish assemblages in Gulf of Mexico coastal streams

Science.gov (United States)

William R. Budnick; William E. Kelso; Susan B. Adams; Michael D. Kaller

2018-01-01

Identifying an effective protocol for sampling crayfish in streams that vary in habitat and physical/chemical characteristics has proven problematic. We evaluated an active, combined-gear (backpack electrofishing and dipnetting) sampling protocol in 20 Coastal Plain streams in Louisiana. Using generalized linear models and rarefaction curves, we evaluated environmental...

Interactions between crayfish, benthic invertebrates, macrophyte roots and sediment in a littoral zone

Czech Academy of Sciences Publication Activity Database

Ságová-Marečková, Markéta

2002-01-01

Roč. 155, č. 4 (2002), s. 645-665 ISSN 0003-9136 Grant - others:GA the Center for Limnology of the UW-Madison(XX) BSR8514330 Institutional research plan: CEZ:AV0Z5020903 Keywords : predation * food * crayfish Subject RIV: EE - Microbiology, Virology Impact factor: 1.195, year: 2002

ROUNDTABLE SESSION 2B: NATIONAL INTERACTIONS BETWEEN NON-INDIGENOUS AND INDIGENOUS CRAYFISH SPECIES

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GHERARDI F.

2002-07-01

Full Text Available The main object of the present essay is to summarise some aspects underlying the interactions between non-indigenous (NICS and indigenous (ICS crayfish species. The discussion has been also extended to the effects exercised by NICS on the natural habitats they occupy. While doing research on the dyads NICS/ICS, one starting point is to extrapolate common traits that make NICS good invaders from the analysis of their biology, ecology and ethology and the comparison with indigenous species. A subsequent step is to switch attention to the understanding of the characteristics that make ecosystems less vulnerable to invasions and then to analyse both the complex interactions of invaders and target communities and the negative and positive impacts exerted by NICS on the occupied habitats. Examples from Sweden, Britain, and Italy have shown that NICS can replace the native species by a combination of several interacting mechanisms. Besides the transmission of the crayfish plague fungus, mechanisms into action include mostly competitive interference, but also diverse life history traits, recruitment failure, differential susceptibility to predation, and reproductive interference. It has been claimed that invasion theory is full of rules of thumb that, having no precise predictive powers, are thus useless to guide reliable public policy. The solution of the prediction problem requires an in-depth study of every potential invader and target community, trespassing the boundaries among disciplines and having a look at crayfish as a whole and not a single entity. The expectation is thus the return to precise and clear empirical generalisations that can be most useful to develop management strategies.

Tritium uptake kinetics in crayfish (Orconectes immunis)

International Nuclear Information System (INIS)

Patrick, P.H.

1985-06-01

Uptake of tritiated water (HTO) by Orconectes immunis was investigated under laboratory conditions. Tritium uptake in the tissue-free water fraction (TFWT) was described using an exponential model. When steady-state was reached, the ratio of TFWT to HTO was approximately 0.9. Uptake of tritium in the organically-bound fraction (OBT) proceeded slowly, and had not reached steady-state after 117 days of culture. Although steady-state was never reached, the maximum observed ration of OBT to TFWT in whole animals was approximately 0.6. However, this ratio exceeded unity in the exoskeleton. Specific activity ratios of OBT between crayfish and lettuce (food source) were less than or at unity for various test conditions

Herbivore preference for native vs. exotic plants: generalist herbivores from multiple continents prefer exotic plants that are evolutionarily naïve.

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Wendy E Morrison

2011-03-01

Full Text Available Enemy release and biotic resistance are competing, but not mutually exclusive, hypotheses addressing the success or failure of non-native plants entering a new region. Enemy release predicts that exotic plants become invasive by escaping their co-adapted herbivores and by being unrecognized or unpalatable to native herbivores that have not been selected to consume them. In contrast, biotic resistance predicts that native generalist herbivores will suppress exotic plants that will not have been selected to deter these herbivores. We tested these hypotheses using five generalist herbivores from North or South America and nine confamilial pairs of native and exotic aquatic plants. Four of five herbivores showed 2.4-17.3 fold preferences for exotic over native plants. Three species of South American apple snails (Pomacea sp. preferred North American over South American macrophytes, while a North American crayfish Procambarus spiculifer preferred South American, Asian, and Australian macrophytes over North American relatives. Apple snails have their center of diversity in South America, but a single species (Pomacea paludosa occurs in North America. This species, with a South American lineage but a North American distribution, did not differentiate between South American and North American plants. Its preferences correlated with preferences of its South American relatives rather than with preferences of the North American crayfish, consistent with evolutionary inertia due to its South American lineage. Tests of plant traits indicated that the crayfish responded primarily to plant structure, the apple snails primarily to plant chemistry, and that plant protein concentration played no detectable role. Generalist herbivores preferred non-native plants, suggesting that intact guilds of native, generalist herbivores may provide biotic resistance to plant invasions. Past invasions may have been facilitated by removal of native herbivores, introduction of

CRAYFISH PREDATION ON TADPOLES : A COMPARISON BETWEEN A NATIVE (AUSTROPOTAMOBIUS PALLIPES AND AN ALIEN SPECIES (PROCAMBARUS CLARKII.

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GHERARDI F.

2001-04-01

Full Text Available In the laboratory, the motivation and/or ability to prey on anuran larvae (Bufo bufo, Rana kl. esculenta and R. italica were compared between a native European (Austropotamobius pallipes and an alien North American crayfish species (Procambarus clarkii. Both were skilled predators of tadpoles, adopting a sit-and-wait strategy. However, because P. clarkii displayed lower latency times in the presence of one of the three amphibians (Rana kl. esculenta here tested, the hypothesis is raised that invasive crayfish are more opportunistic predators and possibly faster in switching to different prey than those species they are displacing. From a conservation perspective, these preliminary results further emphasise the importance of studies centred on the invasion-displacement dichotomy.

Stone crayfish in the Czech Republic: how does its population density depend on basic chemical and physical properties of water?

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Vlach P.

2013-03-01

Full Text Available The stone crayfish (Austropotamobius torrentium Schrank is one of the two native crayfish species in the Czech Republic. The populations as well as physical and chemical parameters of water (pH, conductivity, dissolved oxygen, undissolved particles, NH3, NH4+, NO2−, NO3−, phosphorus, Ca2+ and SO42 −  of 33 streams were examined to find the ecological plasticity of this crayfish and some relations between these parameters and population densities. The mentioned parameters often significantly varied at the sites. Two approaches were applied to find relations between these parameters and observed abundance. At first, the observed streams were compared using RDA (streams  ×  physical-chemical parameters. No significance was found while testing relationship between the streams grouped along the 1st axis of model and the observed abundances of stone crayfish. However, some correlations between abundance and conductivity, calcium, nitrates and sulphates were found using polynomial regression. These relationships are explicable in terms of mutual correlations, underlying geology and other factors which affect abundances. In conclusion, A. torrentium is able to inhabit waters with a large range of physical and chemical parameters of the water without any fundamental influence on population densities. Water properties play an indisputable role as limiting ecological factors at uncommon concentrations, but population densities are probably influenced much more by the types of habitats, habitat features, predation and other ecological factors.

EFFECTS OF RATION SIZE AND TEMPERATURE ON MOULT INCREMENT AND METABOLIC PARAMETERS OF JUVENILE NOBLE CRAYFISH, ASTACUS ASTACUS

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RENAI B.

2007-07-01

Full Text Available A laboratory experiment was carried out to test the combined effects of ration size (1 vs 3% body weight, b.w. and temperature (15 ± 2 vs 22 ± 2 °C on moult increment and metabolic parameters of 80 juvenile noble crayfish (Astacus astacus. The maximum daily consumption (Cmax and respiration rate (R were used to calculate the growth scope (i.e. the difference between maximum daily energy consumption and energy costs at a given temperature. The conversion of R into a food-equivalent unit allowed the comparison with Cmax. Results showed that crayfish obtained the maximum moult increment when fed 3% b.w. while temperature seemed to play a less relevant role on growth rate per moult, affecting only the moulting frequency. Crayfish A. astacus fed ad libitum showed a relative insensitivity to the metabolic parameters (oxygen uptake, R and Cmax within the analysed range of temperatures, possibly as a reflection of this “species” distribution across a broad variety of habitats with different thermal regimes. In the present study, A. astacus displayed characteristics proper of a K-selected species, as slow to moderate growth.

Investigating the genetic and epigenetic basis of big biological questions with the parthenogenetic marbled crayfish: A review and perspectives.

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Vogt, Gunter

2018-03-01

In the last 15 years, considerable attempts have been undertaken to develop the obligately parthenogenetic marbled crayfish Procambarus virginalis as a new model in biology. Its main advantage is the production of large numbers of offspring that are genetically identical to the mother, making this crustacean particularly suitable for research in epigenetics. Now, a draft genome, transcriptome and genome-wide methylome are available opening new windows for research. In this article, I summarize the biological advantages and genomic and epigenetic features of marbled crayfish and, based on first promising data, discuss what this new model could contribute to answering of ''big'' biological questions. Genome mining is expected to reveal new insights into the genetic specificities of decapod crustaceans, the genetic basis of arthropod reproduction, moulting and immunity, and more general topics such as the genetic underpinning of adaptation to fresh water, omnivory, biomineralization, sexual system change, behavioural variation, clonal genome evolution, and resistance to cancer. Epigenetic investigations with the marbled crayfish can help clarifying the role of epigenetic mechanisms in gene regulation, tissue specification, adult stem cell regulation, cell ageing, organ regeneration and disease susceptibility. Marbled crayfish is further suitable to elucidate the relationship between genetic and epigenetic variation, the transgenerational inheritance of epigenetic signatures and the contribution of epigenetic phenotype variation to the establishment of social hierarchies, environmental adaptation and speciation. These issues can be tackled by experiments with highly standardized laboratory lineages, comparison of differently adapted wild populations and the generation of genetically and epigenetically edited strains.

The effect of sensory feedback on crayfish posture and locomotion: II. Neuromechanical simulation of closing the loop.

Science.gov (United States)

Bacqué-Cazenave, Julien; Chung, Bryce; Cofer, David W; Cattaert, Daniel; Edwards, Donald H

2015-03-15

Neuromechanical simulation was used to determine whether proposed thoracic circuit mechanisms for the control of leg elevation and depression in crayfish could account for the responses of an experimental hybrid neuromechanical preparation when the proprioceptive feedback loop was open and closed. The hybrid neuromechanical preparation consisted of a computational model of the fifth crayfish leg driven in real time by the experimentally recorded activity of the levator and depressor (Lev/Dep) nerves of an in vitro preparation of the crayfish thoracic nerve cord. Up and down movements of the model leg evoked by motor nerve activity released and stretched the model coxobasal chordotonal organ (CBCO); variations in the CBCO length were used to drive identical variations in the length of the live CBCO in the in vitro preparation. CBCO afferent responses provided proprioceptive feedback to affect the thoracic motor output. Experiments performed with this hybrid neuromechanical preparation were simulated with a neuromechanical model in which a computational circuit model represented the relevant thoracic circuitry. Model simulations were able to reproduce the hybrid neuromechanical experimental results to show that proposed circuit mechanisms with sensory feedback could account for resistance reflexes displayed in the quiescent state and for reflex reversal and spontaneous Lev/Dep bursting seen in the active state. Copyright © 2015 the American Physiological Society.

Effects of temperature on the acute toxicity of heavy metals (Cr, Cd, and Hg) to the freshwater crayfish, Procambarus clarkii (Girard)

Energy Technology Data Exchange (ETDEWEB)

Del Ramo, J.; Diaz-Mayans, J.; Torreblanca, A.; Nunez, A.

1987-05-01

Chromium, an essential trace element for humans and animals is involved in normal carbohydrate metabolism; however, it is toxic at high concentrations. There is no evidence that cadmium and mercury are biologically essential but their toxicity for organisms is well known. Both cause toxic effects at low concentrations to most organisms, especially in combination with other environmental variables such as temperature. Lake Albufera and the surrounding rice field waters are subjected to very heavy loads of sewage and toxic industrial residues (including heavy metals) from the many urban and waste waters in this area. In 1978, the American red crayfish Procambarus clarkii appeared in lake Albufera and in the surrounding rice fields. Without adequate sanitary control, the crayfish is presently being fished commercially for human consumption. The purpose of the present study is to evaluate the degree of toxicity of various heavy metals (chromium, cadmium and mercury) to freshwater crayfish Procambarus clarkii at various temperatures.

Native and Non-native English Teachers' Perceptions of their Professional Identity: Convergent or Divergent?

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Zia Tajeddin

2016-10-01

Full Text Available There is still a preference for native speaker teachers in the language teaching profession, which is supposed to influence the self-perceptions of native and nonnative teachers. However, the status of English as a globalized language is changing the legitimacy of native/nonnative teacher dichotomy. This study sought to investigate native and nonnative English-speaking teachers’ perceptions about native and nonnative teachers’ status and the advantages and disadvantages of being a native or nonnative teacher. Data were collected by means of a questionnaire and a semi-structured interview. A total of 200 native and nonnative teachers of English from the UK and the US, i.e. the inner circle, and Turkey and Iran, the expanding circle, participated in this study. A significant majority of nonnative teachers believed that native speaker teachers have better speaking proficiency, better pronunciation, and greater self-confidence. The findings also showed nonnative teachers’ lack of self-confidence and awareness of their role and status compared with native-speaker teachers, which could be the result of existing inequities between native and nonnative English-speaking teachers in ELT. The findings also revealed that native teachers disagreed more strongly with the concept of native teachers’ superiority over nonnative teachers. Native teachers argued that nonnative teachers have a good understanding of teaching methodology whereas native teachers are more competent in correct language. It can be concluded that teacher education programs in the expanding-circle countries should include materials for teachers to raise their awareness of their own professional status and role and to remove their misconception about native speaker fallacy.

Wildland fire in ecosystems: fire and nonnative invasive plants

Science.gov (United States)

Kristin Zouhar; Jane Kapler Smith; Steve Sutherland; Matthew L. Brooks

2008-01-01

This state-of-knowledge review of information on relationships between wildland fire and nonnative invasive plants can assist fire managers and other land managers concerned with prevention, detection, and eradication or control of nonnative invasive plants. The 16 chapters in this volume synthesize ecological and botanical principles regarding relationships between...

Non-native Speech Learning in Older Adults.

Science.gov (United States)

Ingvalson, Erin M; Nowicki, Casandra; Zong, Audrey; Wong, Patrick C M

2017-01-01

Though there is an extensive literature investigating the ability of younger adults to learn non-native phonology, including investigations into individual differences in younger adults' lexical tone learning, very little is known about older adults' ability to learn non-native phonology, including lexical tone. There are several reasons to suspect that older adults would use different learning mechanisms when learning lexical tone than younger adults, including poorer perception of dynamic pitch, greater reliance on working memory capacity in second language learning, and poorer category learning in older adulthood. The present study examined the relationships among older adults' baseline sensitivity for pitch patterns, working memory capacity, and declarative memory capacity with their ability to learn to associate tone with lexical meaning. In older adults, baseline pitch pattern sensitivity was not associated with generalization performance. Rather, older adults' learning performance was best predicted by declarative memory capacity. These data suggest that training paradigms will need to be modified to optimize older adults' non-native speech sound learning success.

Non-native fishes in Florida freshwaters: a literature review and synthesis

Science.gov (United States)

Schofield, Pamela J.; Loftus, William F.

2015-01-01

Non-native fishes have been known from freshwater ecosystems of Florida since the 1950s, and dozens of species have established self-sustaining populations. Nonetheless, no synthesis of data collected on those species in Florida has been published until now. We searched the literature for peer-reviewed publications reporting original data for 42 species of non-native fishes in Florida that are currently established, were established in the past, or are sustained by human intervention. Since the 1950s, the number of non-native fish species increased steadily at a rate of roughly six new species per decade. Studies documented (in decreasing abundance): geographic location/range expansion, life- and natural-history characteristics (e.g., diet, habitat use), ecophysiology, community composition, population structure, behaviour, aquatic-plant management, and fisheries/aquaculture. Although there is a great deal of taxonomic uncertainty and confusion associated with many taxa, very few studies focused on clarifying taxonomic ambiguities of non-native fishes in the State. Most studies were descriptive; only 15 % were manipulative. Risk assessments, population-control studies and evaluations of effects of non-native fishes were rare topics for research, although they are highly valued by natural-resource managers. Though some authors equated lack of data with lack of effects, research is needed to confirm or deny conclusions. Much more is known regarding the effects of lionfish (Pterois spp.) on native fauna, despite its much shorter establishment time. Natural-resource managers need biological and ecological information to make policy decisions regarding non-native fishes. Given the near-absence of empirical data on effects of Florida non-native fishes, and the lengthy time-frames usually needed to collect such information, we provide suggestions for data collection in a manner that may be useful in the evaluation and prediction of non-native fish effects.

Fishes, mussels, crayfishes, and aquatic habitats of the Hoosier-Shawnee ecological assessment area

Science.gov (United States)

M. Burr Brooks; Justin T. Sipiorski; Matthew R. Thomas; Kevin S. Cummings; Christopher A. Taylor

2004-01-01

The Hoosier-Shawnee Ecological Assessment Area, part of the Coastal Plain and Interior Low Plateau physiographic provinces, includes 194 native fish species, 76 native mussel species, and 34 native crayfish species. Five of the subregions (e.g., Mississippi Embayment) that make up the assessment area were recently ranked as either globally or bioregionally outstanding...

Characterization of a molt-inhibiting hormone (MIH) of the crayfish, Orconectes limosus, by cDNA cloning and mass spectrometric analysis.

Science.gov (United States)

Bulau, Patrick; Okuno, Atsuro; Thome, Elke; Schmitz, Tina; Peter-Katalinic, Jasna; Keller, Rainer

2005-11-01

The structure of the precursor of a molt-inhibiting hormone (MIH) of the American crayfish, Orconectes limosus was determined by cloning of a cDNA based on RNA from the neurosecretory perikarya of the X-organ in the eyestalk ganglia. The open reading frame includes the complete precursor sequence, consisting of a signal peptide of 29, and the MIH sequence of 77 amino acids. In addition, the mature peptide was isolated by HPLC from the neurohemal sinus gland and analyzed by ESI-MS and MALDI-TOF-MS peptide mapping. This showed that the mature peptide (Mass 8664.29 Da) consists of only 75 amino acids, having Ala75-NH2 as C-terminus. Thus, C-terminal Arg77 of the precursor is removed during processing, and Gly76 serves as an amide donor. Sequence comparison confirms this peptide as a novel member of the large family, which includes crustacean hyperglycaemic hormone (CHH), MIH and gonad (vitellogenesis)-inhibiting hormone (GIH/VIH). The lack of a CPRP (CHH-precursor related peptide) in the hormone precursor, the size and specific sequence characteristics show that Orl MIH belongs to the MIH/GIH(VIH) subgroup of this larger family. Comparison with the MIH of Procambarus clarkii, the only other MIH that has thus far been identified in freshwater crayfish, shows extremely high sequence conservation. Both MIHs differ in only one amino acid residue ( approximately 99% identity), whereas the sequence identity to several other known MIHs is between 40 and 46%.

An Ecosystem-Service Approach to Evaluate the Role of Non-Native Species in Urbanized Wetlands

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Rita S. W. Yam

2015-04-01

Full Text Available Natural wetlands have been increasingly transformed into urbanized ecosystems commonly colonized by stress-tolerant non-native species. Although non-native species present numerous threats to natural ecosystems, some could provide important benefits to urbanized ecosystems. This study investigated the extent of colonization by non-native fish and bird species of three urbanized wetlands in subtropical Taiwan. Using literature data the role of each non-native species in the urbanized wetland was evaluated by their effect (benefits/damages on ecosystem services (ES based on their ecological traits. Our sites were seriously colonized by non-native fishes (39%–100%, but <3% by non-native birds. Although most non-native species could damage ES regulation (disease control and wastewater purification, some could be beneficial to the urbanized wetland ES. Our results indicated the importance of non-native fishes in supporting ES by serving as food source to fish-eating waterbirds (native, and migratory species due to their high abundance, particularly for Oreochromis spp. However, all non-native birds are regarded as “harmful” species causing important ecosystem disservices, and thus eradication of these bird-invaders from urban wetlands would be needed. This simple framework for role evaluation of non-native species represents a holistic and transferable approach to facilitate decision making on management priority of non-native species in urbanized wetlands.

Exploring Native and Non-Native Intuitions of Word Frequency.

Science.gov (United States)

Schmitt, Norbert; Dunham, Bruce

1999-01-01

Asked native and nonnative speakers to give judgments of frequency for near synonyms in second-language lexical sets and compared those responses to modern corpus word counts. Native speakers were able to discern the core word in lexical sets either 77% or 85%, and nonnative speakers at 71% or 79%. (Author/VWL)

Feedback in online course for non-native English-speaking students

CERN Document Server

Olesova, Larisa

2013-01-01

Feedback in Online Course for Non-Native English-Speaking Students is an investigation of the effectiveness of audio and text feedback provided in English in an online course for non-native English-speaking students. The study presents results showing how audio and text feedback can impact on non-native English-speaking students' higher-order learning as they participate in an asynchronous online course. It also discusses the results of how students perceive both types of the feedback provided. In addition, the study examines how the impact and perceptions differ when the instructor giving the

Muscle receptor organs in the crayfish abdomen: a student laboratory exercise in proprioception.

Science.gov (United States)

Leksrisawat, Bonnie; Cooper, Ann S; Gilberts, Allison B; Cooper, Robin L

2010-11-18

The primary purpose of this experiment is to demonstrate primary sensory neurons conveying information of joint movements and positions as proprioceptive information for an animal. An additional objective of this experiment is to learn anatomy of the preparation by staining, dissection and viewing of neurons and sensory structures under a dissecting microscope. This is performed by using basic neurophysiological equipment to record the electrical activity from a joint receptor organ and staining techniques. The muscle receptor organ (MRO) system in the crayfish is analogous to the intrafusal muscle spindle in mammals, which aids in serving as a comparative model that is more readily accessible for electrophysiological recordings. In addition, these are identifiable sensory neurons among preparations. The preparation is viable in a minimal saline for hours which is amenable for student laboratory exercises. The MRO is also susceptible to neuromodulation which encourages intriguing questions in the sites of modulatory action and integration of dynamic signals of movements and static position along with a gain that can be changed in the system.

The Non-Native English Speaker Teachers in TESOL Movement

Science.gov (United States)

Kamhi-Stein, Lía D.

2016-01-01

It has been almost 20 years since what is known as the non-native English-speaking (NNES) professionals' movement--designed to increase the status of NNES professionals--started within the US-based TESOL International Association. However, still missing from the literature is an understanding of what a movement is, and why non-native English…

Importance of small fishes and invasive crayfish in otter Lutra lutra diet in an English chalk stream

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Britton J. Robert

2017-01-01

Full Text Available The diet composition of the European otter Lutra lutra was assessed using spraint analysis in the Hampshire Avon, a lowland chalk stream in Southern England, over an 18-month period. Small cyprinid fishes were the main prey item taken in all seasons, with bullhead Cottus gobio and stone loach Barbatula barbatula also important; there were relatively few larger fishes of interest to fisheries found. There were significant seasonal differences in diet composition by season, with signal crayfish Pacifastacus leniusculus only being prominent prey items in warmer months and amphibians in winter, revealing that non-fish resources were seasonally important dietary components. Reconstructed body lengths of prey revealed the only species present in diet >350 mm was pike Esox lucius. These dietary data thus provide important information for informing conservation conflicts between otters and fishery interests.

Crayfish Self-Administer Amphetamine in a Spatially Contingent Task

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Udita Datta

2018-05-01

Full Text Available Natural reward is an essential element of any organism’s ability to adapt to environmental variation. Its underlying circuits and mechanisms guide the learning process as they help associate an event, or cue, with the perception of an outcome’s value. More generally, natural reward serves as the fundamental generator of all motivated behavior. Addictive plant alkaloids are able to activate this circuitry in taxa ranging from planaria to humans. With modularly organized nervous systems and confirmed vulnerabilities to human drugs of abuse, crayfish have recently emerged as a compelling model for the study of the addiction cycle, including psychostimulant effects, sensitization, withdrawal, reinstatement, and drug reward in conditioned place preference paradigms. Here we extend this work with the demonstration of a spatially contingent, operant drug self-administration paradigm for amphetamine. When the animal enters a quadrant of the arena with a particular textured substrate, a computer-based control system delivers amphetamine through an indwelling fine-bore cannula. Resulting reward strength, dose-response, and the time course of operant conditioning were assessed. Individuals experiencing the drug contingent on their behavior, displayed enhanced rates of operant responses compared to that of their yoked (non-contingent counterparts. Application of amphetamine near the supra-esophageal ganglion elicited stronger and more robust increases in operant responding than did systemic infusions. This work demonstrates automated implementation of a spatially contingent self-administration paradigm in crayfish, which provides a powerful tool to explore comparative perspectives in drug-sensitive reward, the mechanisms of learning underlying the addictive cycle, and phylogenetically conserved vulnerabilities to psychostimulant compounds.

Comprehending non-native speakers: theory and evidence for adjustment in manner of processing.

Science.gov (United States)

Lev-Ari, Shiri

2014-01-01

Non-native speakers have lower linguistic competence than native speakers, which renders their language less reliable in conveying their intentions. We suggest that expectations of lower competence lead listeners to adapt their manner of processing when they listen to non-native speakers. We propose that listeners use cognitive resources to adjust by increasing their reliance on top-down processes and extracting less information from the language of the non-native speaker. An eye-tracking study supports our proposal by showing that when following instructions by a non-native speaker, listeners make more contextually-induced interpretations. Those with relatively high working memory also increase their reliance on context to anticipate the speaker's upcoming reference, and are less likely to notice lexical errors in the non-native speech, indicating that they take less information from the speaker's language. These results contribute to our understanding of the flexibility in language processing and have implications for interactions between native and non-native speakers.

An Ecosystem-Service Approach to Evaluate the Role of Non-Native Species in Urbanized Wetlands

Science.gov (United States)

Yam, Rita S. W.; Huang, Ko-Pu; Hsieh, Hwey-Lian; Lin, Hsing-Juh; Huang, Shou-Chung

2015-01-01

Natural wetlands have been increasingly transformed into urbanized ecosystems commonly colonized by stress-tolerant non-native species. Although non-native species present numerous threats to natural ecosystems, some could provide important benefits to urbanized ecosystems. This study investigated the extent of colonization by non-native fish and bird species of three urbanized wetlands in subtropical Taiwan. Using literature data the role of each non-native species in the urbanized wetland was evaluated by their effect (benefits/damages) on ecosystem services (ES) based on their ecological traits. Our sites were seriously colonized by non-native fishes (39%–100%), but wetland ES. Our results indicated the importance of non-native fishes in supporting ES by serving as food source to fish-eating waterbirds (native, and migratory species) due to their high abundance, particularly for Oreochromis spp. However, all non-native birds are regarded as “harmful” species causing important ecosystem disservices, and thus eradication of these bird-invaders from urban wetlands would be needed. This simple framework for role evaluation of non-native species represents a holistic and transferable approach to facilitate decision making on management priority of non-native species in urbanized wetlands. PMID:25860870

Native fruit traits may mediate dispersal competition between native and non-native plants

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Clare Aslan

2012-02-01

Full Text Available Seed disperser preferences may mediate the impact of invasive, non-native plant species on their new ecological communities. Significant seed disperser preference for invasives over native species could facilitate the spread of the invasives while impeding native plant dispersal. Such competition for dispersers could negatively impact the fitness of some native plants. Here, we review published literature to identify circumstances under which preference for non-native fruits occurs. The importance of fruit attraction is underscored by several studies demonstrating that invasive, fleshy-fruited plant species are particularly attractive to regional frugivores. A small set of studies directly compare frugivore preference for native vs. invasive species, and we find that different designs and goals within such studies frequently yield contrasting results. When similar native and non-native plant species have been compared, frugivores have tended to show preference for the non-natives. This preference appears to stem from enhanced feeding efficiency or accessibility associated with the non-native fruits. On the other hand, studies examining preference within existing suites of co-occurring species, with no attempt to maximize fruit similarity, show mixed results, with frugivores in most cases acting opportunistically or preferring native species. A simple, exploratory meta-analysis finds significant preference for native species when these studies are examined as a group. We illustrate the contrasting findings typical of these two approaches with results from two small-scale aviary experiments we conducted to determine preference by frugivorous bird species in northern California. In these case studies, native birds preferred the native fruit species as long as it was dissimilar from non-native fruits, while non-native European starlings preferred non-native fruit. However, native birds showed slight, non-significant preference for non-native fruit

Non-Native & Native English Teachers

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İrfan Tosuncuoglu

2017-12-01

Full Text Available In many countries the primary (mother tongue language is not English but there is a great demand for English language teachers all over the world. The demand in this field is try to be filled largely by non-native English speaking teachers who have learned English in the country or abroad, or from another non native English peaking teachers. In some countries, particularly those where English speaking is a a sign of status, the students prefer to learn English from a native English speaker. The perception is that a non-native English speaking teacher is a less authentic teacher than a native English speaker and their instruction is not satifactory in some ways. This paper will try to examine the literature to explore whether there is a difference in instructional effectiveness between NNESTs and native English teachers.

Genetic characterization of Western European noble crayfish populations (Astacus astacus) for advanced conservation management strategies

NARCIS (Netherlands)

Schrimpf, A.; Piscione, M.; Cammaerts, R.; Collas, M.; Herman, D.; Jung, A.; Ottburg, F.; Roessink, I.; Rollin, X.; Schulz, R.; Theissinger, K.

2017-01-01

One central goal of conservation biology is to conserve the genetic diversity of species in order to protect their adaptive potential. The main objective of this study was to identify management units (MUs) for the threatened noble crayfish (Astacus astacus) in Western Europe by utilizing

Increased microsporidian parasitism of the crayfish Orconectes virilis in an experimentally acidified lake. [Thelohania contejeani

Energy Technology Data Exchange (ETDEWEB)

France, R.L.; Graham, L.

1985-10-01

Orconectes virilis has been identified as a host of the microsporidian Thelohania contejeani in four lakes in the Experimental Lakes Area (ELA), northwestern Ontario. Prevalence of parasitism increased from 1.7% in autumn 1979, to 6.5% and 7.7% in autumns 1980 and 1981 concomitant with experimental acidification of Lake 223 to pH 5.1. By comparison, mean infection rates observed within three reference lakes were between 0.3 to 0.6%. Enhanced microsporidosis is believed to have contributed to a reduction in annual crayfish survival rates for the Lake 223 population of 8% in 1979 and 18% in 1980 compared to averages calculated for the non-acidified lakes. Hypotheses to explain the ten-fold increase in Thelohania parasitism in Lake 223 over background levels for the ELA region include a) increased probagative ability due to elevated rate of crayfish cannibalism or low pH-favored parasite life cycle, and b) decreased host resistance when under sublethal stress.

NIS occurrence - Non-native species impacts on threatened and endangered salmonids

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The objectives of this project: a) Identify the distribution of non-natives in the Columbia River Basin b) Highlight the impacts of non-natives on salmonids c)...

Kalispel Non-Native Fish Suppression Project 2007 Annual Report.

Energy Technology Data Exchange (ETDEWEB)

Wingert, Michele; Andersen, Todd [Kalispel Natural Resource Department

2008-11-18

Non-native salmonids are impacting native salmonid populations throughout the Pend Oreille Subbasin. Competition, hybridization, and predation by non-native fish have been identified as primary factors in the decline of some native bull trout (Salvelinus confluentus) and westslope cutthroat trout (Oncorhynchus clarki lewisi) populations. In 2007, the Kalispel Natural Resource Department (KNRD) initiated the Kalispel Nonnative Fish Suppression Project. The goal of this project is to implement actions to suppress or eradicate non-native fish in areas where native populations are declining or have been extirpated. These projects have previously been identified as critical to recovering native bull trout and westslope cutthroat trout (WCT). Lower Graham Creek was invaded by non-native rainbow (Oncorhynchus mykiss) and brook trout (Salvelinus fontinalis) after a small dam failed in 1991. By 2003, no genetically pure WCT remained in the lower 700 m of Graham Creek. Further invasion upstream is currently precluded by a relatively short section of steep, cascade-pool stepped channel section that will likely be breached in the near future. In 2008, a fish management structure (barrier) was constructed at the mouth of Graham Creek to preclude further invasion of non-native fish into Graham Creek. The construction of the barrier was preceded by intensive electrofishing in the lower 700 m to remove and relocate all captured fish. Westslope cutthroat trout have recently been extirpated in Cee Cee Ah Creek due to displacement by brook trout. We propose treating Cee Cee Ah Creek with a piscicide to eradicate brook trout. Once eradication is complete, cutthroat trout will be translocated from nearby watersheds. In 2004, the Washington Department of Fish and Wildlife (WDFW) proposed an antimycin treatment within the subbasin; the project encountered significant public opposition and was eventually abandoned. However, over the course of planning this 2004 project, little public

Non-natives: 141 scientists object

NARCIS (Netherlands)

Simberloff, D.; Van der Putten, W.H.

2011-01-01

Supplementary information to: Non-natives: 141 scientists object Full list of co-signatories to a Correspondence published in Nature 475, 36 (2011); doi: 10.1038/475036a. Daniel Simberloff University of Tennessee, Knoxville, Tennessee, USA. dsimberloff@utk.edu Jake Alexander Institute of Integrative

DNA metabarcoding of fish larvae for detection of non-native fishes

Science.gov (United States)

Our objective was to evaluate the use of fish larvae for early detection of non-native fishes, comparing traditional and molecular taxonomy approaches to investigate potential efficiencies. Fish larvae present an interesting opportunity for non-native fish early detection because...

The influence of coarse-scale environmental features on current and predicted future distributions of narrow-range endemic crayfish populations

Science.gov (United States)

Dyer, Joseph J.; Brewer, Shannon K.; Worthington, Thomas A.; Bergey, Elizabeth A.

2013-01-01

1.A major limitation to effective management of narrow-range crayfish populations is the paucity of information on the spatial distribution of crayfish species and a general understanding of the interacting environmental variables that drive current and future potential distributional patterns. 2.Maximum Entropy Species Distribution Modeling Software (MaxEnt) was used to predict the current and future potential distributions of four endemic crayfish species in the Ouachita Mountains. Current distributions were modelled using climate, geology, soils, land use, landform and flow variables thought to be important to lotic crayfish. Potential changes in the distribution were forecast by using models trained on current conditions and projecting onto the landscape predicted under climate-change scenarios. 3.The modelled distribution of the four species closely resembled the perceived distribution of each species but also predicted populations in streams and catchments where they had not previously been collected. Soils, elevation and winter precipitation and temperature most strongly related to current distributions and represented 6587% of the predictive power of the models. Model accuracy was high for all models, and model predictions of new populations were verified through additional field sampling. 4.Current models created using two spatial resolutions (1 and 4.5km2) showed that fine-resolution data more accurately represented current distributions. For three of the four species, the 1-km2 resolution models resulted in more conservative predictions. However, the modelled distributional extent of Orconectes leptogonopodus was similar regardless of data resolution. Field validations indicated 1-km2 resolution models were more accurate than 4.5-km2 resolution models. 5.Future projected (4.5-km2 resolution models) model distributions indicated three of the four endemic species would have truncated ranges with low occurrence probabilities under the low-emission scenario

A nonnative and a native fungal plant pathogen similarly stimulate ectomycorrhizal development but are perceived differently by a fungal symbiont.

Science.gov (United States)

Zampieri, Elisa; Giordano, Luana; Lione, Guglielmo; Vizzini, Alfredo; Sillo, Fabiano; Balestrini, Raffaella; Gonthier, Paolo

2017-03-01

The effects of plant symbionts on host defence responses against pathogens have been extensively documented, but little is known about the impact of pathogens on the symbiosis and if such an impact may differ for nonnative and native pathogens. Here, this issue was addressed in a study of the model system comprising Pinus pinea, its ectomycorrhizal symbiont Tuber borchii, and the nonnative and native pathogens Heterobasidion irregulare and Heterobasidion annosum, respectively. In a 6-month inoculation experiment and using both in planta and gene expression analyses, we tested the hypothesis that H. irregulare has greater effects on the symbiosis than H. annosum. Although the two pathogens induced the same morphological reaction in the plant-symbiont complex, with mycorrhizal density increasing exponentially with pathogen colonization of the host, the number of target genes regulated in T. borchii in plants inoculated with the native pathogen (i.e. 67% of tested genes) was more than twice that in plants inoculated with the nonnative pathogen (i.e. 27% of genes). Although the two fungal pathogens did not differentially affect the amount of ectomycorrhizas, the fungal symbiont perceived their presence differently. The results may suggest that the symbiont has the ability to recognize a self/native and a nonself/nonnative pathogen, probably through host plant-mediated signal transduction. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

Periphyton density is similar on native and non-native plant species

NARCIS (Netherlands)

Grutters, B.M.C.; Gross, Elisabeth M.; van Donk, E.; Bakker, E.S.

2017-01-01

Non-native plants increasingly dominate the vegetation in aquatic ecosystems and thrive in eutrophic conditions. In eutrophic conditions, submerged plants risk being overgrown by epiphytic algae; however, if non-native plants are less susceptible to periphyton than natives, this would contribute to

Non-native earthworms promote plant invasion by ingesting seeds and modifying soil properties

Science.gov (United States)

Clause, Julia; Forey, Estelle; Lortie, Christopher J.; Lambert, Adam M.; Barot, Sébastien

2015-04-01

Earthworms can have strong direct effects on plant communities through consumption and digestion of seeds, however it is unclear how earthworms may influence the relative abundance and composition of plant communities invaded by non-native species. In this study, earthworms, seed banks, and the standing vegetation were sampled in a grassland of central California. Our objectives were i) to examine whether the abundances of non-native, invasive earthworm species and non-native grassland plant species are correlated, and ii) to test whether seed ingestion by these worms alters the soil seed bank by evaluating the composition of seeds in casts relative to uningested soil. Sampling locations were selected based on historical land-use practices, including presence or absence of tilling, and revegetation by seed using Phalaris aquatica. Only non-native earthworm species were found, dominated by the invasive European species Aporrectodea trapezoides. Earthworm abundance was significantly higher in the grassland blocks dominated by non-native plant species, and these sites had higher carbon and moisture contents. Earthworm abundance was also positively related to increased emergence of non-native seedlings, but had no effect on that of native seedlings. Plant species richness and total seedling emergence were higher in casts than in uningested soils. This study suggests that there is a potential effect of non-native earthworms in promoting non-native and likely invasive plant species within grasslands, due to seed-plant-earthworm interactions via soil modification or to seed ingestion by earthworms and subsequent cast effects on grassland dynamics. This study supports a growing body of literature for earthworms as ecosystem engineers but highlights the relative importance of considering non-native-native interactions with the associated plant community.

Unique structural modulation of a non-native substrate by cochaperone DnaJ.

Science.gov (United States)

Tiwari, Satyam; Kumar, Vignesh; Jayaraj, Gopal Gunanathan; Maiti, Souvik; Mapa, Koyeli

2013-02-12

The role of bacterial DnaJ protein as a cochaperone of DnaK is strongly appreciated. Although DnaJ unaccompanied by DnaK can bind unfolded as well as native substrate proteins, its role as an individual chaperone remains elusive. In this study, we demonstrate that DnaJ binds a model non-native substrate with a low nanomolar dissociation constant and, more importantly, modulates the structure of its non-native state. The structural modulation achieved by DnaJ is different compared to that achieved by the DnaK-DnaJ complex. The nature of structural modulation exerted by DnaJ is suggestive of a unique unfolding activity on the non-native substrate by the chaperone. Furthermore, we demonstrate that the zinc binding motif along with the C-terminal substrate binding domain of DnaJ is necessary and sufficient for binding and the subsequent binding-induced structural alterations of the non-native substrate. We hypothesize that this hitherto unknown structural alteration of non-native states by DnaJ might be important for its chaperoning activity by removing kinetic traps of the folding intermediates.

Factors influencing non-native tree species distribution in urban landscapes

Science.gov (United States)

Wayne C. Zipperer

2010-01-01

Non-native species are presumed to be pervasive across the urban landscape. Yet, we actually know very little about their actual distribution. For this study, vegetation plot data from Syracuse, NY and Baltimore, MD were used to examine non-native tree species distribution in urban landscapes. Data were collected from remnant and emergent forest patches on upland sites...

Non-native species impacts on pond occupancy by an anuran

Science.gov (United States)

Adams, Michael J.; Pearl, Christopher A.; Galvan, Stephanie; McCreary, Brome

2011-01-01

Non-native fish and bullfrogs (Lithobates catesbeianus; Rana catesbeiana) are frequently cited as factors contributing to the decline of ranid frogs in the western United States (Bradford 2005). This hypothesis is supported by studies showing competition with or predation by these introduced species (Kupferberg 1997, Kiesecker and Blaustein 1998, Lawler et al. 1999, Knapp et al. 2001) and studies suggesting a deficit of native frogs at sites occupied by bullfrogs or game fish (Hammerson 1982, Schwalbe and Rosen 1988, Fisher and Shaffer 1996, Adams 1999). Conversely, other studies failed to find a negative association between native ranids and bullfrogs and point out that presence of non-native species correlates with habitat alterations that could also contribute to declines of native species (Hayes and Jennings 1986; Adams 1999, 2000; Pearl et al. 2005). A criticism of these studies is that they may not detect an effect of non-native species if the process of displacement is at an early stage. We are not aware of any studies that have monitored a set of native frog populations to determine if non-native species predict population losses. Our objective was to study site occupancy trends in relation to non-native species for northern red-legged frogs (Rana aurora) on federal lands in the southern Willamette Valley, Oregon. We conducted a 5-yr monitoring study to answer the following questions about the status and trends of the northern red-legged frog: 1) What is the rate of local extinction (how often is a site that is occupied in year t unoccupied in year t+1) and what factors predict variation in local extinction? and 2) What is the rate of colonization (how often is a site that is unoccupied in year t occupied in year t+1) and what factors predict variation in colonization? The factors we hypothesized for local extinction were: 1) bullfrog presence, 2) bullfrogs mediated by wetland vegetation, 3) non-native fish (Centrarchidae), 4) non-native fish mediated by

No positive feedback between fire and a nonnative perennial grass

Science.gov (United States)

Erika L. Geiger; Guy R. McPherson

2005-01-01

Semi-desert grasslands flank the “Sky Island” mountains in southern Arizona and Northern Mexico. Many of these grasslands are dominated by nonnative grasses, which potentially alter native biotic communities. One specific concern is the potential for a predicted feedback between nonnative grasses and fire. In a large-scale experiment in southern Arizona we investigated...

Managing conflicts arising from fisheries enhancements based on non-native fishes in southern Africa.

Science.gov (United States)

Ellender, B R; Woodford, D J; Weyl, O L F; Cowx, I G

2014-12-01

Southern Africa has a long history of non-native fish introductions for the enhancement of recreational and commercial fisheries, due to a perceived lack of suitable native species. This has resulted in some important inland fisheries being based on non-native fishes. Regionally, these introductions are predominantly not benign, and non-native fishes are considered one of the main threats to aquatic biodiversity because they affect native biota through predation, competition, habitat alteration, disease transfer and hybridization. To achieve national policy objectives of economic development, food security and poverty eradication, countries are increasingly looking towards inland fisheries as vehicles for development. As a result, conflicts have developed between economic and conservation objectives. In South Africa, as is the case for other invasive biota, the control and management of non-native fishes is included in the National Environmental Management: Biodiversity Act. Implementation measures include import and movement controls and, more recently, non-native fish eradication in conservation priority areas. Management actions are, however, complicated because many non-native fishes are important components in recreational and subsistence fisheries that contribute towards regional economies and food security. In other southern African countries, little attention has focussed on issues and management of non-native fishes, and this is cause for concern. This paper provides an overview of introductions, impacts and fisheries in southern Africa with emphasis on existing and evolving legislation, conflicts, implementation strategies and the sometimes innovative approaches that have been used to prioritize conservation areas and manage non-native fishes. © 2014 The Fisheries Society of the British Isles.

Effects of cadmium on the biochemical composition of the freshwater crayfish Procambarus clarkii (Girard, 1852)

Energy Technology Data Exchange (ETDEWEB)

Torreblanca, A.; Del Ramo, J.; Diaz-Mayans, J. (Univ. of Valencia (Spain))

1991-12-01

Lake Albufera of Valencia (Spain) and the surrounding rice field waters are subjected to very heavy loads of sewage and toxic residues. Among these residues include heavy metals which have been deposited from the many urban and waste waters in this area. The American red crayfish, Procambarus clarkii from Albufera Lake has high resistance to heavy metals. The authors have also found that P. clarkii shows a high capacity for cadmium accumulation in experimental conditions and natural conditions since crayfish collected in this area contained considerable amounts of cadmium in several tissues even after 15 days of depuration in clean water. Since the physiological changes that take place when organisms are exposed to sublethal levels of stress could include rate of feeding as well as respiration and excretion, the net result could be a change in energy available for growth and reproduction. In this work, the authors have studied the biochemical energy composition of hepatopancreas, muscle and gills of P. clarkii after short term sublethal exposure to cadmium.

Exploring public perception of non-native species from a visions of nature perspective.

Science.gov (United States)

Verbrugge, Laura N H; Van den Born, Riyan J G; Lenders, H J Rob

2013-12-01

Not much is known about lay public perceptions of non-native species and their underlying values. Public awareness and engagement, however, are important aspects in invasive species management. In this study, we examined the relations between the lay public's visions of nature, their knowledge about non-native species, and their perceptions of non-native species and invasive species management with a survey administered in the Netherlands. Within this framework, we identified three measures for perception of non-native species: perceived risk, control and engagement. In general, respondents scored moderate values for perceived risk and personal engagement. However, in case of potential ecological or human health risks, control measures were supported. Respondents' images of the human-nature relationship proved to be relevant in engagement in problems caused by invasive species and in recognizing the need for control, while images of nature appeared to be most important in perceiving risks to the environment. We also found that eradication of non-native species was predominantly opposed for species with a high cuddliness factor such as mammals and bird species. We conclude that lay public perceptions of non-native species have to be put in a wider context of visions of nature, and we discuss the implications for public support for invasive species management.

Ecological disequilibrium drives insect pest and pathogen accumulation in non-native trees.

Science.gov (United States)

Crous, Casparus J; Burgess, Treena I; Le Roux, Johannes J; Richardson, David M; Slippers, Bernard; Wingfield, Michael J

2016-12-23

Non-native trees have become dominant components of many landscapes, including urban ecosystems, commercial forestry plantations, fruit orchards, and as invasives in natural ecosystems. Often, these trees have been separated from their natural enemies (i.e. insects and pathogens) leading to ecological disequilibrium, that is, the immediate breakdown of historically co-evolved interactions once introduced into novel environments. Long-established, non-native tree plantations provide useful experiments to explore the dimensions of such ecological disequilibria. We quantify the status quo of non-native insect pests and pathogens catching up with their tree hosts (planted Acacia, Eucalyptus and Pinus species) in South Africa, and examine which native South African enemy species utilise these trees as hosts. Interestingly, pines, with no confamilial relatives in South Africa and the longest residence time (almost two centuries), have acquired only one highly polyphagous native pathogen. This is in contrast to acacias and eucalypts, both with many native and confamilial relatives in South Africa that have acquired more native pathogens. These patterns support the known role of phylogenetic relatedness of non-native and native floras in influencing the likelihood of pathogen shifts between them. This relationship, however, does not seem to hold for native insects. Native insects appear far more likely to expand their feeding habits onto non-native tree hosts than are native pathogens, although they are generally less damaging. The ecological disequilibrium conditions of non-native trees are deeply rooted in the eco-evolutionary experience of the host plant, co-evolved natural enemies, and native organisms from the introduced range. We should expect considerable spatial and temporal variation in ecological disequilibrium conditions among non-native taxa, which can be significantly influenced by biosecurity and management practices. Published by Oxford University Press on

Effects of ecological restoration alternative treatments on nonnative plant species establishment

Science.gov (United States)

Michael T. Stoddard; Christopher M. McGlone; Peter Z. Fule

2008-01-01

Disturbances generated by forest restoration treatments have the potential for enhancing the establishment of nonnative species thereby impeding long-term native plant recovery. In a ponderosa pine forest next to the Fort Valley Experimental Forest, Arizona, we examined the establishment of nonnative species after three alternative treatments with different intensities...

Non-native earthworms promote plant invasion by ingesting seeds and modifying soil properties

OpenAIRE

Clause, J.; Forey, E.; Lortie, C. J.; Lambert, A. M.; Barot, Sébastien

2015-01-01

Earthworms can have strong direct effects on plant communities through consumption and digestion of seeds, however it is unclear how earthworms may influence the relative abundance and composition of plant communities invaded by non-native species. In this study, earthworms, seed banks, and the standing vegetation were sampled in a grassland of central California. Our objectives were i) to examine whether the abundances of non-native, invasive earthworm species and non-native grassland plant ...

Information to support to monitoring and habitat restoration on Ash Meadows National Wildlife Refuge

Science.gov (United States)

Scoppettone, G. Gary

2013-01-01

The Ash Meadows National Wildlife Refuge staff focuses on improving habitat for the highest incidence of endemic species for an area of its size in the continental United States. Attempts are being made to restore habitat to some semblance of its pre-anthropogenic undisturbed condition, and to provide habitat conditions to which native plant and animal species have evolved. Unfortunately, restoring the Ash Meadows’ Oases to its pre-anthropogenic undisturbed condition is almost impossible. First, there are constraints on water manipulation because there are private holdings within the refuge boundary; second, there has been at least one species extinction—the Ash Meadows pool fish (Empetrichthys merriami). It is also quite possible that thermal endemic invertebrate species were lost before ever being described. Perhaps the primary obstacle to restoring Ash Meadows to its pre-anthropogenic undisturbed conditions is the presence of invasive species. However, invasive species, such as red swamp crayfish (Procambarus clarki) and western mosquitofish (Gambusia affinis), are a primary driving force in restoring Ash Meadows’ spring systems, because under certain habitat conditions they can all but replace native species. Returning Ash Meadows’ physical landscape to some semblance of its pre-anthropogenic undisturbed condition through natural processes may take decades. Meanwhile, the natural dissolution of concrete and earthen irrigation channels threatens to allow cattail marshes to flourish instead of spring-brooks immediately downstream of spring discharge. This successional stage favors non-native crayfish and mosquitofish over the native Amargosa pupfish (Cyprinodon nevadensis). Thus, restoration is needed to control non-natives and to promote native species, and without such intervention the probability of native fish reduction or loss, is anticipated. The four studies in this report are intended to provide information for restoring native fish habitat and

Invasive non-native species' provision of refugia for endangered native species.

Science.gov (United States)

Chiba, Satoshi

2010-08-01

The influence of non-native species on native ecosystems is not predicted easily when interspecific interactions are complex. Species removal can result in unexpected and undesired changes to other ecosystem components. I examined whether invasive non-native species may both harm and provide refugia for endangered native species. The invasive non-native plant Casuarina stricta has damaged the native flora and caused decline of the snail fauna on the Ogasawara Islands, Japan. On Anijima in 2006 and 2009, I examined endemic land snails in the genus Ogasawarana. I compared the density of live specimens and frequency of predation scars (from black rats [Rattus rattus]) on empty shells in native vegetation and Casuarina forests. The density of land snails was greater in native vegetation than in Casuarina forests in 2006. Nevertheless, radical declines in the density of land snails occurred in native vegetation since 2006 in association with increasing predation by black rats. In contrast, abundance of Ogasawarana did not decline in the Casuarina forest, where shells with predation scars from rats were rare. As a result, the density of snails was greater in the Casuarina forest than in native vegetation. Removal of Casuarina was associated with an increased proportion of shells with predation scars from rats and a decrease in the density of Ogasawarana. The thick and dense litter of Casuarina appears to provide refugia for native land snails by protecting them from predation by rats; thus, eradication of rats should precede eradication of Casuarina. Adaptive strategies, particularly those that consider the removal order of non-native species, are crucial to minimizing the unintended effects of eradication on native species. In addition, my results suggested that in some cases a given non-native species can be used to mitigate the impacts of other non-native species on native species.

Community-level plant-soil feedbacks explain landscape distribution of native and non-native plants.

Science.gov (United States)

Kulmatiski, Andrew

2018-02-01

Plant-soil feedbacks (PSFs) have gained attention for their potential role in explaining plant growth and invasion. While promising, most PSF research has measured plant monoculture growth on different soils in short-term, greenhouse experiments. Here, five soil types were conditioned by growing one native species, three non-native species, or a mixed plant community in different plots in a common-garden experiment. After 4 years, plants were removed and one native and one non-native plant community were planted into replicate plots of each soil type. After three additional years, the percentage cover of each of the three target species in each community was measured. These data were used to parameterize a plant community growth model. Model predictions were compared to native and non-native abundance on the landscape. Native community cover was lowest on soil conditioned by the dominant non-native, Centaurea diffusa , and non-native community cover was lowest on soil cultivated by the dominant native, Pseudoroegneria spicata . Consistent with plant growth on the landscape, the plant growth model predicted that the positive PSFs observed in the common-garden experiment would result in two distinct communities on the landscape: a native plant community on native soils and a non-native plant community on non-native soils. In contrast, when PSF effects were removed, the model predicted that non-native plants would dominate all soils, which was not consistent with plant growth on the landscape. Results provide an example where PSF effects were large enough to change the rank-order abundance of native and non-native plant communities and to explain plant distributions on the landscape. The positive PSFs that contributed to this effect reflected the ability of the two dominant plant species to suppress each other's growth. Results suggest that plant dominance, at least in this system, reflects the ability of a species to suppress the growth of dominant competitors

Non-native species in the vascular flora of highlands and mountains of Iceland

Directory of Open Access Journals (Sweden)

Pawel Wasowicz

2016-01-01

Full Text Available The highlands and mountains of Iceland are one of the largest remaining wilderness areas in Europe. This study aimed to provide comprehensive and up-to-date data on non-native plant species in these areas and to answer the following questions: (1 How many non-native vascular plant species inhabit highland and mountainous environments in Iceland? (2 Do temporal trends in the immigration of alien species to Iceland differ between highland and lowland areas? (3 Does the incidence of alien species in the disturbed and undisturbed areas within Icelandic highlands differ? (4 Does the spread of non-native species in Iceland proceed from lowlands to highlands? and (5 Can we detect hot-spots in the distribution of non-native taxa within the highlands? Overall, 16 non-native vascular plant species were detected, including 11 casuals and 5 naturalized taxa (1 invasive. Results showed that temporal trends in alien species immigration to highland and lowland areas are similar, but it is clear that the process of colonization of highland areas is still in its initial phase. Non-native plants tended to occur close to man-made infrastructure and buildings including huts, shelters, roads etc. Analysis of spatio-temporal patterns showed that the spread within highland areas is a second step in non-native plant colonization in Iceland. Several statically significant hot spots of alien plant occurrences were identified using the Getis-Ord Gi* statistic and these were linked to human disturbance. This research suggests that human-mediated dispersal is the main driving force increasing the risk of invasion in Iceland’s highlands and mountain areas.

Arthropod assemblages on native and nonnative plant species of a coastal reserve in California.

Science.gov (United States)

Fork, Susanne K

2010-06-01

Biological invasions by nonnative plant species are a widespread phenomenon. Many studies have shown strong ecological impacts of plant invasions on native plant communities and ecosystem processes. Far fewer studies have examined effects on associated animal communities. From the perspective of a reserve's land management, I addressed the question of whether arthropod assemblages on two nonnative plant species of concern were impoverished compared with those assemblages associated with two predominant native plant species of that reserve. If the nonnative plant species, Conium maculatum L., and Phalaris aquatica L., supported highly depauperate arthropod assemblages compared with the native plant species, Baccharis pilularis De Candolle and Leymus triticoides (Buckley) Pilger, this finding would provide additional support for prioritizing removal of nonnatives and restoration of natives. I assessed invertebrate assemblages at the taxonomic levels of arthropod orders, Coleoptera families, and Formicidae species, using univariate analyses to examine community attributes (richness and abundance) and multivariate techniques to assess arthropod assemblage community composition differences among plant species. Arthropod richness estimates by taxonomic level between native and nonnative vegetation showed varying results. Overall, arthropod richness of the selected nonnative plants, examined at higher taxonomic resolution, was not necessarily less diverse than two of common native plants found on the reserve, although differences were found among plant species. Impacts of certain nonnative plant species on arthropod assemblages may be more difficult to elucidate than those impacts shown on native plants and ecosystem processes.

Positive and Negative Impacts of Non-Native Bee Species around the World.

Science.gov (United States)

Russo, Laura

2016-11-28

Though they are relatively understudied, non-native bees are ubiquitous and have enormous potential economic and environmental impacts. These impacts may be positive or negative, and are often unquantified. In this manuscript, I review literature on the known distribution and environmental and economic impacts of 80 species of introduced bees. The potential negative impacts of non-native bees include competition with native bees for nesting sites or floral resources, pollination of invasive weeds, co-invasion with pathogens and parasites, genetic introgression, damage to buildings, affecting the pollination of native plant species, and changing the structure of native pollination networks. The potential positive impacts of non-native bees include agricultural pollination, availability for scientific research, rescue of native species, and resilience to human-mediated disturbance and climate change. Most non-native bee species are accidentally introduced and nest in stems, twigs, and cavities in wood. In terms of number of species, the best represented families are Megachilidae and Apidae, and the best represented genus is Megachile . The best studied genera are Apis and Bombus , and most of the species in these genera were deliberately introduced for agricultural pollination. Thus, we know little about the majority of non-native bees, accidentally introduced or spreading beyond their native ranges.

Positive and Negative Impacts of Non-Native Bee Species around the World

Directory of Open Access Journals (Sweden)

Laura Russo

2016-11-01

Full Text Available Though they are relatively understudied, non-native bees are ubiquitous and have enormous potential economic and environmental impacts. These impacts may be positive or negative, and are often unquantified. In this manuscript, I review literature on the known distribution and environmental and economic impacts of 80 species of introduced bees. The potential negative impacts of non-native bees include competition with native bees for nesting sites or floral resources, pollination of invasive weeds, co-invasion with pathogens and parasites, genetic introgression, damage to buildings, affecting the pollination of native plant species, and changing the structure of native pollination networks. The potential positive impacts of non-native bees include agricultural pollination, availability for scientific research, rescue of native species, and resilience to human-mediated disturbance and climate change. Most non-native bee species are accidentally introduced and nest in stems, twigs, and cavities in wood. In terms of number of species, the best represented families are Megachilidae and Apidae, and the best represented genus is Megachile. The best studied genera are Apis and Bombus, and most of the species in these genera were deliberately introduced for agricultural pollination. Thus, we know little about the majority of non-native bees, accidentally introduced or spreading beyond their native ranges.

A Lota lota consumption: Trophic dynamics of nonnative Burbot in a valuable sport fishery

Science.gov (United States)

Klobucar, Stephen L.; Saunders, W. Carl; Budy, Phaedra

2016-01-01

Unintentional and illegal introductions of species disrupt food webs and threaten the success of managed sport fisheries. Although many populations of Burbot Lota lota are declining in the species’ native range, a nonnative population recently expanded into Flaming Gorge Reservoir (FGR), Wyoming–Utah, and threatens to disrupt predator–prey interactions within this popular sport fishery. To determine potential impacts on sport fishes, especially trophy Lake Trout Salvelinus namaycush, we assessed the relative abundance of Burbot and quantified the potential trophic or food web impacts of this population by using diet, stable isotope, and bioenergetic analyses. We did not detect a significant potential for food resource competition between Burbot and Lake Trout (Schoener’s overlap index = 0.13), but overall consumption by Burbot likely affects other sport fishes, as indicated by our analyses of trophic niche space. Diet analyses suggested that crayfish were important diet items across time (89.3% of prey by weight in autumn; 49.4% in winter) and across Burbot size-classes (small: 77.5% of prey by weight; medium: 76.6%; large: 39.7%). However, overall consumption by Burbot increases as water temperatures cool, and fish consumption by Burbot in FGR was observed to increase during winter. Specifically, large Burbot consumed more salmonids, and we estimated (bioenergetically) that up to 70% of growth occurred in late autumn and winter. Further, our population-wide consumption estimates indicated that Burbot could consume up to double the biomass of Rainbow Trout Oncorhynchus mykiss stocked annually (>1.3 × 105 kg; >1 million individuals) into FGR. Overall, we provide some of the first information regarding Burbot trophic interactions outside of the species’ native range; these findings can help to inform the management of sport fisheries if Burbot range expansion occurs elsewhere.

Non-native Species in Floodplain Secondary Forests in Peninsular Malaysia

Directory of Open Access Journals (Sweden)

Nor Rasidah Hashim

2010-01-01

Full Text Available There is an increasing concern of alien species invading our tropical ecosystems because anthropogenic land use can create conditions in which non-native species thrive. This study is an assessment of bioinvasion using a quantitative survey of non-native plant species in floodplain secondary forests in Peninsular Malaysia. The study area is known to have a long cultivation and settlement history that provides ample time for non-native species introduction. The survey results showed that introduced species constituted 23% of all the identified species, with seven species unique to riparian forest strips and eleven species unique to abandoned paddy fields and the remaining five species being shared between the two secondary forest types. There existed some habitat preferences amongst the species implying both secondary forests were potentially susceptible to bioinvasion. Fourteen species are also invasive elsewhere (PIER invasives whereas fifteen species have acquired local uses such for traditional medicine and food products. The presence of these non-native species could alter native plant succession trajectory, and eventually leads to native species impoverishment if the exotics managed to outcompete the native species. As such, the findings of this study have a far-reaching application for the national biodiversity conservation efforts because it provides the required information on bioinvasion.

Effects of Nonnative Ungulate Removal on Plant Communities and Soil Biogeochemistry in Tropical Forests

Science.gov (United States)

Cole, R. J.; Litton, C. M.; Giardina, C. P.; Sparks, J. P.

2014-12-01

Non-native ungulates have substantial impacts on native ecosystems globally, altering both plant communities and soil biogeochemistry. Across tropical and temperate ecosystems, land managers fence and remove non-native ungulates to conserve native biodiversity, a costly management action, yet long-term outcomes are not well quantified. Specifically, knowledge gaps include: (i) the magnitude and time frame of plant community recovery; (ii) the response of non-native invasive plants; and (iii) changes to soil biogeochemistry. In 2010, we established a series of paired ungulate presence vs. removal plots that span a 20 yr. chronosequence in tropical montane wet forests on the Island of Hawaii to quantify the impacts and temporal legacy of feral pig removal on plant communities and soil biogeochemistry. We also compared soil biogeochemistry in targeted areas of low and high feral pig impact. Our work shows that both native and non-native vegetation respond positively to release from top-down control following removal of feral pigs, but species of high conservation concern recover only if initially present at the time of non-native ungulate removal. Feral pig impacts on soil biogeochemistry appear to last for at least 20 years following ungulate removal. We observed that both soil physical and chemical properties changed with feral pig removal. Soil bulk density and volumetric water content decreased while extractable base cations and inorganic N increased in low vs. high feral pig impact areas. We hypothesize that altered soil biogeochemistry facilitates continued invasions by non-native plants, even decades after non-native ungulate removal. Future work will concentrate on comparisons between wet and dry forest ecosystems and test whether manipulation of soil nutrients can be used to favor native vs. non-native plant establishment.

Food preference and feeding rhythm in red swamp crayfish Procambarus clarkii%克氏原螯虾的食物选择性及其摄食节律

Institute of Scientific and Technical Information of China (English)

徐增洪; 周鑫; 水燕

2012-01-01

Juvenile and adult red swamp crayfish (Procambarus clarkii) were reared in tanks (60 cm × 40 cm × 40 cm) at a rate of 20 individuals per tank and fed 5 aquatic plant species (Altemanthera philoxeroides, Eichhornia crassipes, Lesser duckweed Lemna minor, Elodea nultallii, and pondweed ValUsneria natans) to evaluate food I-tems and changes in food filling in stomach and intestines during day and night. In addition, the growth was compared in th crayfish reared in a paddyfield and fed three diets ( crayfish feedstuff with 30% protein, aquatic grasses and trash fish). The food in the intestine of the juvenile crayfish was found to be primarily comprised of zooplankton and phytoplankton. The adult crayfish was shown to have lower food preference, almost all of edible aquatic animals and plants, organic detritus, and artificial feed available in waters being consumed, and aquatic plants constituting their main food due to wide distribution, and easy ingesting. The feeding rhythm was observed during day and night in the crayfish culture pond, the two peaks at 8:00-10:00 and 19:00-22:00. There was significantly better growth in the adult crayfish fed Elodea nuttallii, Lesser duckweed and Vallisneria natans than that in the crayfish fed Altemanthera philoxeroides and Eichharnia crassipes(P0. 05) , even though the crayfish fed Lesser duckweed had slightly better growth than the crayfish fed Elodea nuUallii, and ValUsneria natans did. There was significant difference in daily weight gain rate in the juvenile crayfish fed lesser duckweed, Elodea nuttallii, Vallisneria natans, Altemanthera philoxeroides,Eichhornia crassipes(P<0.05). In the rice field, however, the crayfish fed trash fish was shown to have much better growth than that the crayfish fed pelleted food, and pelleted feedstuff combined with aquatic plants.%对克氏原螫虾Procambarus clarkii幼虾和成虾的胃及肠道内的食物组成和食物充塞度的昼夜变化规律进行了观察；在水族箱(60 cm

Non-native Chinese Foreign Language (CFL) Teachers: Identity and Discourse

DEFF Research Database (Denmark)

Zhang, Chun

2014-01-01

Abstract Native Chinese foreign language (CFL) teacher identity is an emerging subject of research interest in the teacher education. Yet, limited study has been done on the construction of Non-native CFL teachers in their home culture. Guided by a concept of teacher identity-in-discourse, the pa......Abstract Native Chinese foreign language (CFL) teacher identity is an emerging subject of research interest in the teacher education. Yet, limited study has been done on the construction of Non-native CFL teachers in their home culture. Guided by a concept of teacher identity...... teachers face tensions and challenges in constructing their identities as CFL teachers, and the tensions and challenges that arose from Danish teaching culture could influence the Non-native CFL teachers' contributions to CFL teaching in their home cultures. The findings further show that in order to cope...

Hobbseus yalobushensis, a crayfish of intermittent streams: Biotic and habitat associations, life history characteristics, and new localities

Science.gov (United States)

Susan B. Adams; Blake A. Davis; Darren A. Miller

2018-01-01

Hobbseus yalobushensis, the Yalobusha rivulet crayfish, is a species of conservation concern because it is known from only six localities in parts of three central Mississippi counties. No studies have focused on the species since its description in 1989. Our objectives were to: (1) identify additional H. yalobushensis...

Invasion of an occupied niche by the crayfish Orconectes rusticus: potential importance of growth and mortality.

Science.gov (United States)

Hill, Anna M; Sinars, Damon M; Lodge, David M

1993-06-01

We are exploring mechanisms of an invasion that contradicts the oft-cited generalization that species invade vacant niches. In northern Wisconsin lakes, the introduced crayfish Orconectes rusticus is replacing two ecologically similar resident congeners, O. virilis and O. propinquus. In laboratory experiments, we compared growth and mortality of individually maintained crayfish offered one of five ad libitum diets: invertebrates, macrophytes, dentritus, periphyton or all items combined. Mortality was highest for O. virilis and lowest for O. rusticus. Macrophyte diets yielded the highest mortality. All three species grew best on invertebrate and combination diets but grew little or not at all on diets of periphyton, detritus or macrophytes. O. rusticus and O. virilis grew more than O. propinquus. O. rusticus grew more quickly and/or was better able to survive overall than its congeners. Therefore, O. rusticus would probably have advantages over O. virilis and O. propinquus in competitive interactions, reproductive success and avoiding size-selective fish predation. Subtle interspecific differences may interact strongly with other ecological factors and contribute to the displacement of resident species from a well-occupied niche.

Biomagnification of some heavy and essential metals in sediments, fishes and crayfish from Ondo State coastal region, Nigeria

International Nuclear Information System (INIS)

Asaolu, S.S.; Olaofe, O.

2005-01-01

The bio magnifications levels of some essential (Fe, Zn, Cu) and toxic metals (Pb, Ni, Cd, Cr, Co, Mn) were determined in sediments, three kinds of fish (Oreochromis niloticus, Synodonthis sp., and Clarias gariepinus) and crayfish from the Ondo State coastal region. The metal bio magnification in the fish and crayfish was several times greater than in water, while that in the sediments was several thousand-folds greater than in both the organisms and water. Among the metals examined in water, Fe was the most abundant with average values of 146.7 and 74.3 mg/1, respectively, for wet and dry seasons, while Co was the least with average values of 2.4 and 1.6 mg/1. In the sediments, concentrations of Pb, Ni, Fe, Cr, Co and Mn in the wet season were relatively higher than those obtained for the dry season. Fe with an average of 50.9 mg/kg in C, gariepinus was the most abundant metal in the fish samples, while Cu with an average value of 0.3 mg/kg in O. niloticus was the least. The metal bio magnification for most of the metals for both seasons was found to vary widely from one location to the other. This was confirmed by the coefficient of variation that ranged from 31% to 144% and 29% to 130% in the wet and dry seasons, respectively. The present study has shown that fish, crayfish and sediments can be used to monitor the pollution level of metals in the Nigerian coastal water. (author)

Show me the numbers: What data currently exist for non-native species in the USA?

Science.gov (United States)

Crall, Alycia W.; Meyerson, Laura A.; Stohlgren, Thomas J.; Jarnevich, Catherine S.; Newman, Gregory J.; Graham, James

2006-01-01

Non-native species continue to be introduced to the United States from other countries via trade and transportation, creating a growing need for early detection and rapid response to new invaders. It is therefore increasingly important to synthesize existing data on non-native species abundance and distributions. However, no comprehensive analysis of existing data has been undertaken for non-native species, and there have been few efforts to improve collaboration. We therefore conducted a survey to determine what datasets currently exist for non-native species in the US from county, state, multi-state region, national, and global scales. We identified 319 datasets and collected metadata for 79% of these. Through this study, we provide a better understanding of extant non-native species datasets and identify data gaps (ie taxonomic, spatial, and temporal) to help guide future survey, research, and predictive modeling efforts.

Do native brown trout and non-native brook trout interact reproductively?

Science.gov (United States)

Cucherousset, J.; Aymes, J. C.; Poulet, N.; Santoul, F.; Céréghino, R.

2008-07-01

Reproductive interactions between native and non-native species of fish have received little attention compared to other types of interactions such as predation or competition for food and habitat. We studied the reproductive interactions between non-native brook trout ( Salvelinus fontinalis) and native brown trout ( Salmo trutta) in a Pyrenees Mountain stream (SW France). We found evidence of significant interspecific interactions owing to consistent spatial and temporal overlap in redd localizations and spawning periods. We observed mixed spawning groups composed of the two species, interspecific subordinate males, and presence of natural hybrids (tiger trout). These reproductive interactions could be detrimental to the reproduction success of both species. Our study shows that non-native species might have detrimental effects on native species via subtle hybridization behavior.

Glutamatergic postsynaptic block by Pamphobeteus spider venoms in crayfish.

Science.gov (United States)

Araque, A; Ferreira, W; Lucas, S; Buño, W

1992-01-31

The effects of toxins from venom glands of two south american spiders (Pamphobeteus platyomma and P. soracabae) on glutamatergic excitatory synaptic transmission were studied in the neuromuscular junction of the opener muscle of crayfish. The toxins selectively and reversibly blocked both excitatory postsynaptic currents and potentials in a dose-dependent manner. They also reversibly abolished glutamate-induced postsynaptic membrane depolarization. They had no effect on resting postsynaptic membrane conductance nor on postsynaptic voltage-gated currents. The synaptic facilitation and the frequency of miniature postsynaptic potentials were unaffected by the toxins, indicating that presynaptic events were not modified. Picrotoxin, a selective antagonist of the gamma-aminobutyric acid (GABA)A receptor, did not modify toxin effects. We conclude that both toxins specifically block the postsynaptic glutamate receptor-channel complex.

Setting Priorities for Monitoring and Managing Non-native Plants: Toward a Practical Approach.

Science.gov (United States)

Koch, Christiane; Jeschke, Jonathan M; Overbeck, Gerhard E; Kollmann, Johannes

2016-09-01

Land managers face the challenge to set priorities in monitoring and managing non-native plant species, as resources are limited and not all non-natives become invasive. Existing frameworks that have been proposed to rank non-native species require extensive information on their distribution, abundance, and impact. This information is difficult to obtain and often not available for many species and regions. National watch or priority lists are helpful, but it is questionable whether they provide sufficient information for environmental management on a regional scale. We therefore propose a decision tree that ranks species based on more simple albeit robust information, but still provides reliable management recommendations. To test the decision tree, we collected and evaluated distribution data from non-native plants in highland grasslands of Southern Brazil. We compared the results with a national list from the Brazilian Invasive Species Database for the state to discuss advantages and disadvantages of the different approaches on a regional scale. Out of 38 non-native species found, only four were also present on the national list. If management would solely rely on this list, many species that were identified as spreading based on the decision tree would go unnoticed. With the suggested scheme, it is possible to assign species to active management, to monitoring, or further evaluation. While national lists are certainly important, management on a regional scale should employ additional tools that adequately consider the actual risk of non-natives to become invasive.

Concentrations of elements in fish fillets, fish muscle plugs, and crayfish from the 2007 Missouri Department of Conservation General Contaminant Monitoring Program

Science.gov (United States)

May, Thomas W.; Walther, Michael J.; Brumbaugh, William G.; McKee, Michael J.

2009-01-01

This report presents the results of a contaminant monitoring survey conducted annually by the Missouri Department of Conservation to examine the levels of selected elemental contaminants in fish fillets, fish muscle plugs, and crayfish. Fillets of channel catfish (Ictalurus punctatus), bass (Micropterus salmoides, Micropterus dolomieu, Morone chrysops), walleye (Sander vitreus), common carp (Cyprinus carpio), lake sturgeon (Acipenser fulvescens), northern hog sucker (Hypentelium nigricans), and rainbow trout (Oncorhynchus mykiss) were collected from 21 sites as part of the Department's Fish Contaminant Monitoring Program. Long-pincered crayfish (Orconectes longidigitus) were collected from one site to assess trophic transfer of metals to fish. Fish muscle plugs were collected from smallmouth bass (Micropterus dolomieu) at two different locations from one site.

Concentrations of elements in fish fillets, fish muscle plugs, and crayfish from the 2011 Missouri Department of Conservation general contaminant monitoring program

Science.gov (United States)

May, Thomas W.; Walther, Michael J.; Brumbaugh, William G.; McKee, Michael J.

2013-01-01

This report presents the results of a contaminant monitoring survey conducted annually by the Missouri Department of Conservation to examine the levels of selected elemental contaminants in fish fillets, fish muscle plugs, and crayfish. Fillet samples of yellow bullhead (Ameiurus natalis), golden redhorse (Moxostoma erythrurum), longear sunfish (Lepomis megalotis), and channel catfish (Ictalurus punctatus) were collected from six sites as part of the Missouri Department of Conservation’s Fish Contaminant Monitoring Program. Fish dorsal muscle plugs were collected from largemouth bass (Micropterus salmoides) at eight of the sites, and crayfish from two sites. Following preparation and analysis of the samples, highlights of the data were as follows: cadmium and lead residues were most elevated in crayfish tissue samples from the Big River at Cherokee Landing, with 1 to 8 micrograms per gram dry weight and 22 to 45 micrograms per gram dry weight, respectively. Some dorsal muscle plugs from largemouth bass collected from Clearwater Lake, Lake St. Louis, Noblett Lake, Hazel Creek Lake, and Harrison County Lake contained mercury residues (1.7 to 4.7 micrograms per gram dry weight) that exceeded the U.S. Environmental Protection Agency Water Quality Criterion of 1.5 micrograms per gram dry weight of fish tissue (equivalent to 0.30 micrograms per gram wet weight).

Habitat use and population structure of the invasive red swamp crayfish Procambarus clarkii (Girard, 1852 in a protected area in northern Italy

Directory of Open Access Journals (Sweden)

Donato Roberta

2018-01-01

Full Text Available The red swamp crayfish Procambarus clarkii is one of the most invasive alien species in Europe and included in the list of invasive species of Union concern. We describe for the first time some life-history traits of a red swamp crayfish population in the Nature Reserve of the Lago di Candia (Italy. We investigated (1 preferences of this species for specific environmental features on the banks of the lake, and (2 differences in size, sex ratio, and condition index between individuals caught in lake and marsh. Moreover, we compared sampling effort and the features of individuals caught in the lake, for two sampling seasons in 2014 and 2015. Findings indicated that the population was well established, and the marsh seemed to have better conditions for growth of individuals than the lake. Accordingly, continuity of riparian vegetation, opportunity to dig burrows, and trophic resource availability seems to facilitate the proliferation of the crayfish in the lake. Our study demonstrated that massive removal efforts over the whole active period of the species and more than one year of trapping are necessary to increase the controlling activities' success. This study could have important implications for further population management projects directed at biodiversity conservation in the area.

NATIVE VS NON-NATIVE ENGLISH TEACHERS

Directory of Open Access Journals (Sweden)

Masrizal Masrizal

2013-02-01

Full Text Available Although the majority of English language teachers worldwide are non-native English speakers (NNS, no research was conducted on these teachers until recently. A pioneer research by Peter Medgyes in 1994 took quite a long time until the other researchers found their interests in this issue. There is a widespread stereotype that a native speaker (NS is by nature the best person to teach his/her foreign language. In regard to this assumption, we then see a very limited room and opportunities for a non native teacher to teach language that is not his/hers. The aim of this article is to analyze the differences among these teachers in order to prove that non-native teachers have equal advantages that should be taken into account. The writer expects that the result of this short article could be a valuable input to the area of teaching English as a foreign language in Indonesia.

Contrasting xylem vessel constraints on hydraulic conductivity between native and non-native woody understory species

Directory of Open Access Journals (Sweden)

Maria S Smith

2013-11-01

Full Text Available We examined the hydraulic properties of 82 native and non-native woody species common to forests of Eastern North America, including several congeneric groups, representing a range of anatomical wood types. We observed smaller conduit diameters with greater frequency in non-native species, corresponding to lower calculated potential vulnerability to cavitation index. Non-native species exhibited higher vessel-grouping in metaxylem compared with native species, however, solitary vessels were more prevalent in secondary xylem. Higher frequency of solitary vessels in secondary xylem was related to a lower potential vulnerability index. We found no relationship between anatomical characteristics of xylem, origin of species and hydraulic conductivity, indicating that non-native species did not exhibit advantageous hydraulic efficiency over native species. Our results confer anatomical advantages for non-native species under the potential for cavitation due to freezing, perhaps permitting extended growing seasons.

Germination responses of an invasive species in native and non-native ranges

Science.gov (United States)

Jose L. Hierro; Ozkan Eren; Liana Khetsuriani; Alecu Diaconu; Katalin Torok; Daniel Montesinos; Krikor Andonian; David Kikodze; Levan Janoian; Diego Villarreal; Maria Estanga-Mollica; Ragan M. Callaway

2009-01-01

Studying germination in the native and non-native range of a species can provide unique insights into processes of range expansion and adaptation; however, traits related to germination have rarely been compared between native and nonnative populations. In a series of common garden experiments, we explored whether differences in the seasonality of precipitation,...

ANNUAL ACTIVITY OF THE NOBLE CRAYFISH (ASTACUS ASTACUS) IN THE ORLJAVA RIVER (CROATIA)

OpenAIRE

FALLER M.; MAGUIRE I.; KLOBUČAR G.

2006-01-01

We studied the annual activity of the noble crayfish (Astacus astacus) at three sites along the Orljava River, in the continental part of Croatia, between August 2003 and September 2004. Each site represented the typical characteristics of the upper, middle and lower section of the river (5, 24 and 37 km from the spring, respectively). The biggest population size was recorded on the most upstream site, with greatest structural variability of bottom, high biotic index, and the lowest mean wate...

Economic Impacts of Non-Native Forest Insects in the Continental United States

Science.gov (United States)

Juliann E. Aukema; Brian. Leung; Kent Kovacs; Corey Chivers; Jeffrey Englin; Susan J. Frankel; Robert G. Haight; Thomas P. Holmes; Andrew M. Liebhold; Deborah G. McCullough; Betsy. Von Holle

2011-01-01

Reliable estimates of the impacts and costs of biological invasions are critical to developing credible management, trade and regulatory policies. Worldwide, forests and urban trees provide important ecosystem services as well as economic and social benefits, but are threatened by non-native insects. More than 450 non-native forest insects are established in the United...

Lower lethal temperatures for nonnative freshwater fishes in Everglades National Park, Florida

Science.gov (United States)

Schofield, Pam; Kline, Jeffrey L.

2018-01-01

Temperature is an important factor that shapes biogeography and species composition. In southern Florida, the tolerance of nonnative freshwater fishes to low temperatures is a critical factor in delineating their geographic spread. In this study, we provide empirical information on experimentally derived low-temperature tolerance limits of Banded Cichlid Heros severus and Spotfin Spiny Eel Macrognathus siamensis, two nonnative Everglades fishes that were lacking data, and African Jewelfish Hemichromis letourneuxi and Mayan Cichlid Cichlasoma urophthalmus, species for which previous results were derived from studies with small sample sizes. We also provide a literature review summarizing the current state of knowledge of low-temperature tolerances for all 17 nonnative freshwater fishes that have been found in Everglades National Park. Mean lower lethal temperature tolerances ranged from 4°C (Orinoco Sailfin Catfish Pterygoplichthys multiradiatus) to 16.1°C (Butterfly Peacock Bass Cichla ocellaris). These low-temperature limits may inform the understanding of the ecological role or influence of nonnative fishes and may lead to potential management opportunities and applications.

Dissociating Cortical Activity during Processing of Native and Non-Native Audiovisual Speech from Early to Late Infancy

Directory of Open Access Journals (Sweden)

Eswen Fava

2014-08-01

Full Text Available Initially, infants are capable of discriminating phonetic contrasts across the world’s languages. Starting between seven and ten months of age, they gradually lose this ability through a process of perceptual narrowing. Although traditionally investigated with isolated speech sounds, such narrowing occurs in a variety of perceptual domains (e.g., faces, visual speech. Thus far, tracking the developmental trajectory of this tuning process has been focused primarily on auditory speech alone, and generally using isolated sounds. But infants learn from speech produced by people talking to them, meaning they learn from a complex audiovisual signal. Here, we use near-infrared spectroscopy to measure blood concentration changes in the bilateral temporal cortices of infants in three different age groups: 3-to-6 months, 7-to-10 months, and 11-to-14-months. Critically, all three groups of infants were tested with continuous audiovisual speech in both their native and another, unfamiliar language. We found that at each age range, infants showed different patterns of cortical activity in response to the native and non-native stimuli. Infants in the youngest group showed bilateral cortical activity that was greater overall in response to non-native relative to native speech; the oldest group showed left lateralized activity in response to native relative to non-native speech. These results highlight perceptual tuning as a dynamic process that happens across modalities and at different levels of stimulus complexity.

Small mammal use of native warm-season and non-native cool-season grass forage fields

Science.gov (United States)

Ryan L Klimstra,; Christopher E Moorman,; Converse, Sarah J.; Royle, J. Andrew; Craig A Harper,

2015-01-01

Recent emphasis has been put on establishing native warm-season grasses for forage production because it is thought native warm-season grasses provide higher quality wildlife habitat than do non-native cool-season grasses. However, it is not clear whether native warm-season grass fields provide better resources for small mammals than currently are available in non-native cool-season grass forage production fields. We developed a hierarchical spatially explicit capture-recapture model to compare abundance of hispid cotton rats (Sigmodon hispidus), white-footed mice (Peromyscus leucopus), and house mice (Mus musculus) among 4 hayed non-native cool-season grass fields, 4 hayed native warm-season grass fields, and 4 native warm-season grass-forb ("wildlife") fields managed for wildlife during 2 summer trapping periods in 2009 and 2010 of the western piedmont of North Carolina, USA. Cotton rat abundance estimates were greater in wildlife fields than in native warm-season grass and non-native cool-season grass fields and greater in native warm-season grass fields than in non-native cool-season grass fields. Abundances of white-footed mouse and house mouse populations were lower in wildlife fields than in native warm-season grass and non-native cool-season grass fields, but the abundances were not different between the native warm-season grass and non-native cool-season grass fields. Lack of cover following haying in non-native cool-season grass and native warm-season grass fields likely was the key factor limiting small mammal abundance, especially cotton rats, in forage fields. Retention of vegetation structure in managed forage production systems, either by alternately resting cool-season and warm-season grass forage fields or by leaving unharvested field borders, should provide refugia for small mammals during haying events.

Effect of uranium chronic exposure on the moult in crayfish

International Nuclear Information System (INIS)

Simon, O.; Camilleri, V.; Garnier-Laplace, J.

2004-01-01

Throughout any ecological risk assessment, one can try to establish a link between pollutant in the ecosystem and adverse biological effects. A number of methodological approaches are based on the development of the use of bio-markers such as the enzyme activity measurements (biotransformation enzymes, antioxidant enzymes) and/or bioaccumulation markers (metal in target-organs). These data allow obtaining an early-warning signal of exposure and potential involved effects and help risk management. However, the effects at higher hierarchical levels (organism or population) are not frequently considered because they tend to occur after longer exposure periods. On the basis of previous results obtained to quantify uranium biokinetics in the crayfish Orconectes limosus and to understand the influence of the exposure pathway, a chronic exposure experiment was performed for 100 days at an environmentally relevant uranium concentration in water (low level concentration ranging from?? to 100 nM). The main effect studied was focused on the moult; moulted animals being the most sensitive to pollutants. Effects on the moult process were assessed in terms of occurrence, delay, and success. Preliminary results that indicated no induction of the moult by U exposure and better survival rate to uranium exposure must be confirmed. Simultaneously, both enzymatic bio-markers of effect quantifying the oxidative status (catalase, superoxide dismutase and glutathione peroxidases) and markers of exposure (uranium distribution at organs and cellular levels and MET observations) were studied. Results obtained from complementary experiments on the uranium fluxes all over moult states were used to discuss the link between bio-markers responses and observed effects on the moult. (author)

Effect of uranium chronic exposure on the moult in crayfish

Energy Technology Data Exchange (ETDEWEB)

Simon, O.; Camilleri, V.; Garnier-Laplace, J. [CEA Cadarache (DEI/SECRE/LRE), Laboratory of Radioecology and Ecotoxicology, Institute for Radioprotection and Nuclear Safety, 13 - Saint-Paul-lez-Durance (France)

2004-07-01

Throughout any ecological risk assessment, one can try to establish a link between pollutant in the ecosystem and adverse biological effects. A number of methodological approaches are based on the development of the use of bio-markers such as the enzyme activity measurements (biotransformation enzymes, antioxidant enzymes) and/or bioaccumulation markers (metal in target-organs). These data allow obtaining an early-warning signal of exposure and potential involved effects and help risk management. However, the effects at higher hierarchical levels (organism or population) are not frequently considered because they tend to occur after longer exposure periods. On the basis of previous results obtained to quantify uranium biokinetics in the crayfish Orconectes limosus and to understand the influence of the exposure pathway, a chronic exposure experiment was performed for 100 days at an environmentally relevant uranium concentration in water (low level concentration ranging from?? to 100 nM). The main effect studied was focused on the moult; moulted animals being the most sensitive to pollutants. Effects on the moult process were assessed in terms of occurrence, delay, and success. Preliminary results that indicated no induction of the moult by U exposure and better survival rate to uranium exposure must be confirmed. Simultaneously, both enzymatic bio-markers of effect quantifying the oxidative status (catalase, superoxide dismutase and glutathione peroxidases) and markers of exposure (uranium distribution at organs and cellular levels and MET observations) were studied. Results obtained from complementary experiments on the uranium fluxes all over moult states were used to discuss the link between bio-markers responses and observed effects on the moult. (author)

Non-natives: 141 scientists object

OpenAIRE

Simberloff, Daniel; Vilà, Montserrat

2011-01-01

Supplementary information to: Non-natives: 141 scientists object Full list of co-signatories to a Correspondence published in Nature 475, 36 (2011); doi: 10.1038/475036a. Daniel Simberloff University of Tennessee, Knoxville, Tennessee, USA. Jake Alexander Institute of Integrative Biology, Zurich, Switzerland. Fred Allendorf University of Montana, Missoula, Montana, USA. James Aronson CEFE/CNRS, Montpellier, France. Pedro M. Antunes Algoma University, Sault Ste. Marie, Onta...

Heavy metals bioaccumulation in selected tissues of red swamp crayfish: An easy tool for monitoring environmental contamination levels.

Science.gov (United States)

Goretti, E; Pallottini, M; Ricciarini, M I; Selvaggi, R; Cappelletti, D

2016-07-15

In this paper we explored the heavy metal bioaccumulation (Cd, Cu, Pb and Zn) in Procambarus clarkii, a crayfish recently suggested as a potential bioindicator for metals pollution in freshwater systems. The present study is focused on crayfishes populations caught in a heavily polluted industrial and in a reference sites (Central Italy), though the results are generalized with a thorough analysis of literature metadata. In agreement with the literature, the hepatopancreas (Hep, detoxification tissues) of the red swamp crayfish showed a higher concentration of heavy metals in comparison to the abdominal muscle (AbM, not detoxification tissues) in the sites under scrutiny. Hep/AbM concentration ratio was dependent on the specific metal investigated and on its sediment contamination level. Specifically we found that Hep/AbM ratio decreases as follows: Cd (11.7)>Cu (5.5)>Pb (3.6)>Zn (1.0) and Pb (4.34)>Cd (3.66)>Zn (1.69)>Cu (0.87) for the industrial and reference sites, respectively. The analysis of our bioaccumulation data as well as of literature metadata allowed to elaborate a specific contamination index (Toxic Contamination Index, TCI), dependent only on the bioaccumulation data of hepatopancreas and abdominal muscle. In the industrial site, TCI expressed values much higher than the unit for Cd and Cu, confirming that these metals were the main contaminants; in contrast for lower levels of heavy metals, as those observed in the reference site for Cu, Zn and Pb, the index provided values below unit. TCI is proposed as a useful and easy tool to assess the toxicity level of contaminated sites by heavy metals in the environmental management. Copyright © 2016. Published by Elsevier B.V.

Promoting Communities of Practice among Non-Native Speakers of English in Online Discussions

Science.gov (United States)

Kim, Hoe Kyeung

2011-01-01

An online discussion involving text-based computer-mediated communication has great potential for promoting equal participation among non-native speakers of English. Several studies claimed that online discussions could enhance the academic participation of non-native speakers of English. However, there is little research around participation…

Neuromodulation of reciprocal glutamatergic inhibition between antagonistic motoneurons by 5-hydroxytryptamine (5-HT) in crayfish walking system.

Science.gov (United States)

Pearlstein, E; Clarac, F; Cattaert, D

1998-01-23

In an in vitro preparation of the crayfish thoracic locomotor system, paired intracellular recordings were performed from antagonistic depressor (Dep) and levator (Lev) motoneurons (MNs) that control the second joint of walking legs. Connections between these two groups of MNs consist mainly of inhibitory connections and weak electrotonic synapses. Injection of depolarizing current into a Lev MN results in a hyperpolarization in a Dep MN, and vice versa. This reciprocal glutamatergic inhibition, is not changed in the presence of the sodium channel blocker tetrodotoxin (TTX) and therefore is likely supported by a direct connection between MNs. By contrast, reciprocal inhibition is largely reduced in the presence of 5-hydroxytryptamine (5-HT; 10 microM). Direct micro-application of glutamate pressure-ejected close to an intracellularly recorded MN, evoked an inhibitory response in that MN, accompanied by a decrease of input resistance. These two effects were dramatically reduced in the presence of 5-HT. Thus 5-HT could be involved in mechanisms of dynamic reconfigurations of the neural network controlling leg movements in crayfish.

Presence and abundance of non-native plant species associated with recent energy development in the Williston Basin

Science.gov (United States)

Preston, Todd M.

2015-01-01

The Williston Basin, located in the Northern Great Plains, is experiencing rapid energy development with North Dakota and Montana being the epicenter of current and projected development in the USA. The average single-bore well pad is 5 acres with an estimated 58,485 wells in North Dakota alone. This landscape-level disturbance may provide a pathway for the establishment of non-native plants. To evaluate potential influences of energy development on the presence and abundance of non-native species, vegetation surveys were conducted at 30 oil well sites (14 ten-year-old and 16 five-year-old wells) and 14 control sites in native prairie environments across the Williston Basin. Non-native species richness and cover were recorded in four quadrats, located at equal distances, along four transects for a total of 16 quadrats per site. Non-natives were recorded at all 44 sites and ranged from 5 to 13 species, 7 to 15 species, and 2 to 8 species at the 10-year, 5-year, and control sites, respectively. Respective non-native cover ranged from 1 to 69, 16 to 76, and 2 to 82 %. Total, forb, and graminoid non-native species richness and non-native forb cover were significantly greater at oil well sites compared to control sites. At oil well sites, non-native species richness and forb cover were significantly greater adjacent to the well pads and decreased with distance to values similar to control sites. Finally, non-native species whose presence and/or abundance were significantly greater at oil well sites relative to control sites were identified to aid management efforts.

The Impact of Non-Native English Teachers' Linguistic Insecurity on Learners' Productive Skills

Science.gov (United States)

Daftari, Giti Ehtesham; Tavil, Zekiye Müge

2017-01-01

The discrimination between native and non-native English speaking teachers is reported in favor of native speakers in literature. The present study examines the linguistic insecurity of non-native English speaking teachers (NNESTs) and investigates its influence on learners' productive skills by using SPSS software. The eighteen teachers…

Non-native vascular plants from Canary Islands (Spain): nomenclatural and taxonomical adjustments

OpenAIRE

Verloove, F.

2013-01-01

Se propone correcciones taxonómicas y nomenclaturales respecto a 88 taxones no nativos de la lista de plantas vasculares de las Islas Canarias (España). Non-native vascular plants from Canary Islands (Spain): nomenclatural and taxonomical adjustments. Corrections and other adjustments are proposed for 88 non-native taxa from the checklist of vascular plants from the Canary Islands (Spain).

Assessing the consequences of nonnative trout in headwater ecosystems in western North America

Science.gov (United States)

Jason B. Dunham; David S. Pilliod; Michael K. Young

2004-01-01

Intentional introductions of nonnative trout into headwater lakes and streams can have numerous effects on the receiving ecosystems, potentially threatening native species and disrupting key ecological processes. In this perspective, we focus on seven key issues for assessing the biological and economic consequences of nonnative trout in headwater ecosystems: (1)...

Impact of nonnative feral pig removal on soil structure and nutrient availability in Hawaiian tropical montane wet forests

Science.gov (United States)

Michael S. Long; Creighton M. Litton; Christian P. Giardina; Jonathan Deenik; Rebecca J. Cole; Jed P. Sparks

2017-01-01

Conservation and restoration of ecosystems impacted by nonnative ungulates increasingly involves their removal and exclusion. While the influence of nonnative ungulate removal on plant communities is commonly monitored, impacts on underlying ecological processes are seldom quantified. Here we examined how nonnative feral pig (

Non-Native Plant Invasion along Elevation and Canopy Closure Gradients in a Middle Rocky Mountain Ecosystem.

Directory of Open Access Journals (Sweden)

Joshua P Averett

Full Text Available Mountain environments are currently among the ecosystems least invaded by non-native species; however, mountains are increasingly under threat of non-native plant invasion. The slow pace of exotic plant invasions in mountain ecosystems is likely due to a combination of low anthropogenic disturbances, low propagule supply, and extreme/steep environmental gradients. The importance of any one of these factors is debated and likely ecosystem dependent. We evaluated the importance of various correlates of plant invasions in the Wallowa Mountain Range of northeastern Oregon and explored whether non-native species distributions differed from native species along an elevation gradient. Vascular plant communities were sampled in summer 2012 along three mountain roads. Transects (n = 20 were evenly stratified by elevation (~70 m intervals along each road. Vascular plant species abundances and environmental parameters were measured. We used indicator species analysis to identify habitat affinities for non-native species. Plots were ordinated in species space, joint plots and non-parametric multiplicative regression were used to relate species and community variation to environmental variables. Non-native species richness decreased continuously with increasing elevation. In contrast, native species richness displayed a unimodal distribution with maximum richness occurring at mid-elevations. Species composition was strongly related to elevation and canopy openness. Overlays of trait and environmental factors onto non-metric multidimensional ordinations identified the montane-subalpine community transition and over-story canopy closure exceeding 60% as potential barriers to non-native species establishment. Unlike native species, non-native species showed little evidence for high-elevation or closed-canopy specialization. These data suggest that non-native plants currently found in the Wallowa Mountains are dependent on open canopies and disturbance for

Non-Native Plant Invasion along Elevation and Canopy Closure Gradients in a Middle Rocky Mountain Ecosystem.

Science.gov (United States)

Averett, Joshua P; McCune, Bruce; Parks, Catherine G; Naylor, Bridgett J; DelCurto, Tim; Mata-González, Ricardo

2016-01-01

Mountain environments are currently among the ecosystems least invaded by non-native species; however, mountains are increasingly under threat of non-native plant invasion. The slow pace of exotic plant invasions in mountain ecosystems is likely due to a combination of low anthropogenic disturbances, low propagule supply, and extreme/steep environmental gradients. The importance of any one of these factors is debated and likely ecosystem dependent. We evaluated the importance of various correlates of plant invasions in the Wallowa Mountain Range of northeastern Oregon and explored whether non-native species distributions differed from native species along an elevation gradient. Vascular plant communities were sampled in summer 2012 along three mountain roads. Transects (n = 20) were evenly stratified by elevation (~70 m intervals) along each road. Vascular plant species abundances and environmental parameters were measured. We used indicator species analysis to identify habitat affinities for non-native species. Plots were ordinated in species space, joint plots and non-parametric multiplicative regression were used to relate species and community variation to environmental variables. Non-native species richness decreased continuously with increasing elevation. In contrast, native species richness displayed a unimodal distribution with maximum richness occurring at mid-elevations. Species composition was strongly related to elevation and canopy openness. Overlays of trait and environmental factors onto non-metric multidimensional ordinations identified the montane-subalpine community transition and over-story canopy closure exceeding 60% as potential barriers to non-native species establishment. Unlike native species, non-native species showed little evidence for high-elevation or closed-canopy specialization. These data suggest that non-native plants currently found in the Wallowa Mountains are dependent on open canopies and disturbance for establishment in low

Determinants of success in native and non-native listening comprehension: an individual differences approach

NARCIS (Netherlands)

Andringa, S.; Olsthoorn, N.; van Beuningen, C.; Schoonen, R.; Hulstijn, J.

2012-01-01

The goal of this study was to explain individual differences in both native and non-native listening comprehension; 121 native and 113 non-native speakers of Dutch were tested on various linguistic and nonlinguistic cognitive skills thought to underlie listening comprehension. Structural equation

Distribution and establishment of the alien Australian redclaw crayfish, Cherax quadricarinatus, in South Africa and Swaziland

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Ana L. Nunes

2017-04-01

Full Text Available Background The Australian redclaw crayfish (Cherax quadricarinatus, von Martens, is native to Australasia, but has been widely translocated around the world due to aquaculture and aquarium trade. Mostly as a result of escape from aquaculture facilities, this species has established extralimital populations in Australia and alien populations in Europe, Asia, Central America and Africa. In South Africa, C. quadricarinatus was first sampled from the wild in 2002 in the Komati River, following its escape from an aquaculture facility in Swaziland, but data on the current status of its populations are not available. Methods To establish a better understanding of its distribution, rate of spread and population status, we surveyed a total of 46 sites in various river systems in South Africa and Swaziland. Surveys were performed between September 2015 and August 2016 and involved visual observations and the use of collapsible crayfish traps. Results Cherax quadricarinatus is now present in the Komati, Lomati, Mbuluzi, Mlawula and Usutu rivers, and it was also detected in several off-channel irrigation impoundments. Where present, it was generally abundant, with populations having multiple size cohorts and containing ovigerous females. In the Komati River, it has spread more than 112 km downstream of the initial introduction point and 33 km upstream of a tributary, resulting in a mean spread rate of 8 km year−1 downstream and 4.7 km year−1 upstream. In Swaziland, estimated downstream spread rate might reach 14.6 km year−1. Individuals were generally larger and heavier closer to the introduction site, which might be linked to juvenile dispersal. Discussion These findings demonstrate that C. quadricarinatus is established in South Africa and Swaziland and that the species has spread, not only within the river where it was first introduced, but also between rivers. Considering the strong impacts that alien crayfish usually have on invaded ecosystems

A Collaboration-Mediated Exploration of Nonnative L2 Teachers' Cognition of Language Teaching Methodology

Science.gov (United States)

Tajeddin, Zia; Aryaeian, Nafeeseh

2017-01-01

The present study sought to investigate nonnative L2 teachers' cognition of teaching methodology based on their collaborative talks. Participants were 12 nonnative EFL teachers categorized into three collaborative discussion groups by their teaching experience. Collaborative discussions were aimed at exploring the participants' cognition of…

Mitochondrial DNA provides evidence of a double origin for the stone crayfish Austropotamobius torrentium in the Elbe basin

Czech Academy of Sciences Publication Activity Database

Petrusek, A.; Pešek, P.; Leština, Dan; Martin, P.; Fischer, D.; Kozák, P.; Vlach, P.

2017-01-01

Roč. 62, JAN 01 (2017), s. 77-83 ISSN 0075-9511 Institutional support: RVO:60077344 Keywords : stone crayfish * Austropotamobius torrentium * Elbe basin Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Genetics and heredity (medical genetics to be 3) Impact factor: 1.427, year: 2016 https://www.sciencedirect.com/science/article/pii/S0075951116300901

Accelerated hatching of southern leopard frog (Rana sphenocephala) eggs in response to the presence of a crayfish Procambarus nigrocinctus predator

Science.gov (United States)

Daniel Saenz; James B. Johnson; Cory K. Adams; Gage H. Dayton

2003-01-01

Phenotypic plasticity, such as morphological and behavioral changes in response to predators, is common in larval anurans. Less is known about inducible defenses in the embryonic stages of development. We investigated the predation risk imposed by crayfish (Procambarus nigrocinctus) on southern leopard frog (Rana sphenocephala)...

The Role of Fuel Breaks in the Invasion of Nonnative Plants

Science.gov (United States)

Merriam, Kyle E.; Keeley, Jon E.; Beyers, Jan L.

2007-01-01

Executive Summary Fuel reduction projects have become an increasingly important component of state and federal fuels management programs. However, an unintended result of some pre-fire fuel manipulation projects may be the introduction of nonnative invasive plants. The establishment of nonnative plants within fuel breaks is a serious concern because the presence of invasive species in areas treated to reduce fuels could make adjacent wildland areas more susceptible to invasion, particularly following widespread disturbances such as fires. This report presents the results of a research project investigating the relationship between fuel reduction treatments and the invasion of nonnative plants. Throughout the rest of this document, we will collectively refer to these treatments as fuel breaks, although we sampled a range of fuel breaks described variously as fuel breaks, shaded fuel breaks, defensible fuel reduction zones, defensible fuel profile zones, fuel reduction projects, fuel management zones, wildfire protection zones, and community protection zones.

Predation of the alien American mink Mustela vison on native crayfish populations in middle-sized streams in central and western Bohemia

Czech Academy of Sciences Publication Activity Database

Fischer, D.; Pavluvčík, P.; Sedláček, František; Šálek, Martin

2009-01-01

Roč. 58, č. 1 (2009), s. 45-56 ISSN 0139-7893 Institutional research plan: CEZ:AV0Z60870520 Keywords : mink diet * stone crayfish * prey selectivity * density-dependent predation * Czech Republic Subject RIV: EG - Zoology Impact factor: 0.357, year: 2009

Determinants of Success in Native and Non-Native Listening Comprehension: An Individual Differences Approach

Science.gov (United States)

Andringa, Sible; Olsthoorn, Nomi; van Beuningen, Catherine; Schoonen, Rob; Hulstijn, Jan

2012-01-01

The goal of this study was to explain individual differences in both native and non-native listening comprehension; 121 native and 113 non-native speakers of Dutch were tested on various linguistic and nonlinguistic cognitive skills thought to underlie listening comprehension. Structural equation modeling was used to identify the predictors of…

76 FR 20706 - South Farallon Islands Nonnative Mouse Eradication Project; Farallon National Wildlife Refuge...

Science.gov (United States)

2011-04-13

... Noonday Rock. In 1969 the Refuge was expanded to include the South Farallon Islands and is still managed... eradicate nonnative mice from the South Farallon Islands, part of the Farallon National Wildlife Refuge off... eradicate nonnative house mice (Mus musculus) from the South Farallon Islands. The purpose of this project...

Impact of Non-Native Birds on Native Ecosystems: A Global Analysis.

Science.gov (United States)

Martin-Albarracin, Valeria L; Amico, Guillermo C; Simberloff, Daniel; Nuñez, Martin A

2015-01-01

Introduction and naturalization of non-native species is one of the most important threats to global biodiversity. Birds have been widely introduced worldwide, but their impacts on populations, communities, and ecosystems have not received as much attention as those of other groups. This work is a global synthesis of the impact of nonnative birds on native ecosystems to determine (1) what groups, impacts, and locations have been best studied; (2) which taxonomic groups and which impacts have greatest effects on ecosystems, (3) how important are bird impacts at the community and ecosystem levels, and (4) what are the known benefits of nonnative birds to natural ecosystems. We conducted an extensive literature search that yielded 148 articles covering 39 species belonging to 18 families -18% of all known naturalized species. Studies were classified according to where they were conducted: Africa, Asia, Australasia, Europe, North America, South America, Islands of the Indian, of the Pacific, and of the Atlantic Ocean. Seven types of impact on native ecosystems were evaluated: competition, disease transmission, chemical, physical, or structural impact on ecosystem, grazing/ herbivory/ browsing, hybridization, predation, and interaction with other non-native species. Hybridization and disease transmission were the most important impacts, affecting the population and community levels. Ecosystem-level impacts, such as structural and chemical impacts were detected. Seven species were found to have positive impacts aside from negative ones. We provide suggestions for future studies focused on mechanisms of impact, regions, and understudied taxonomic groups.

Predicting establishment of non-native fishes in Greece: identifying key features

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Christos Gkenas

2015-11-01

Full Text Available Non-native fishes are known to cause economic damage to human society and are considered a major threat to biodiversity loss in freshwater ecosystems. The growing concern about these impacts has driven to an investigation of the biological traits that facilitate the establishment of non-native fish. However, invalid assessment in choosing the appropriate statistical model can lead researchers to ambiguous conclusions. Here, we present a comprehensive comparison of traditional and alternative statistical methods for predicting fish invasions using logistic regression, classification trees, multicorrespondence analysis and random forest analysis to determine characteristics of successful and failed non-native fishes in Hellenic Peninsula through establishment. We defined fifteen categorical predictor variables with biological relevance and measures of human interest. Our study showed that accuracy differed according to the model and the number of factors considered. Among all the models tested, random forest and logistic regression performed best, although all approaches predicted non-native fish establishment with moderate to excellent results. Detailed evaluation among the models corresponded with differences in variables importance, with three biological variables (parental care, distance from nearest native source and maximum size and two variables of human interest (prior invasion success and propagule pressure being important in predicting establishment. The analyzed statistical methods presented have a high predictive power and can be used as a risk assessment tool to prevent future freshwater fish invasions in this region with an imperiled fish fauna.

Chinese College Students' Views on Native English and Non-Native English in EFL Classrooms

Science.gov (United States)

Qian, Yang; Jingxia, Liu

2016-01-01

With the development of globalization, English is clearly spoken by many more non-native than native speakers, which raises the discussion of English varieties and the debate regarding the conformity to Standard English. Although a large number of studies have shown scholars' attitudes towards native English and non-native English, little research…

SIFamide peptides in clawed lobsters and freshwater crayfish (Crustacea, Decapoda, Astacidea): a combined molecular, mass spectrometric and electrophysiological investigation.

Science.gov (United States)

Dickinson, Patsy S; Stemmler, Elizabeth A; Cashman, Christopher R; Brennan, Henry R; Dennison, Bobbi; Huber, Kristen E; Peguero, Braulio; Rabacal, Whitney; Goiney, Christopher C; Smith, Christine M; Towle, David W; Christie, Andrew E

2008-04-01

Recently, we identified the peptide VYRKPPFNGSIFamide (Val(1)-SIFamide) in the stomatogastric nervous system (STNS) of the American lobster Homarus americanus using matrix-assisted laser desorption/ionization-Fourier transform mass spectrometry (MALDI-FTMS). Given that H. americanus is the only species thus far shown to possess this peptide, and that a second SIFamide isoform, Gly(1)-SIFamide, is broadly conserved in other decapods, including another astacidean, the crayfish Procambarus clarkii, we became interested both in confirming our identification of Val(1)-SIFamide via molecular methods and in determining the extent to which this isoform is conserved within other members of the infraorder Astacidea. Here, we present the identification and characterization of an H. americanus prepro-SIFamide cDNA that encodes the Val(1) isoform. Moreover, we demonstrate via MALDI-FTMS the presence of Val(1)-SIFamide in a second Homarus species, Homarus gammarus. In contrast, only the Gly(1) isoform was detected in the other astacideans investigated, including the lobster Nephrops norvegicus, a member of the same family as Homarus, and the crayfish Cherax quadricarinatus, P. clarkii and Pacifastacus leniusculus, which represent members of each of the extant families of freshwater astacideans. These results suggest that Val(1)-SIFamide may be a genus (Homarus)-specific isoform. Interestingly, both Val(1)- and Gly(1)-SIFamide possess an internal dibasic site, Arg(3)-Lys(4), raising the possibility of the ubiquitously conserved isoform PPFNGSIFamide. However, this octapeptide was not detected via MALDI-FTMS in any of the investigated species, and when applied to the isolated STNS of H. americanus possessed little bioactivity relative to the full-length Val(1) isoform. Thus, it appears that the dodeca-variants Val(1)- and Gly(1)-SIFamide are the sole bioactive isoforms of this peptide family in clawed lobsters and freshwater crayfish.

Nonnative forest insects and pathogens in the United States: impacts and policy options

Science.gov (United States)

Gary M. Lovett; Marissa Weiss; Andrew M. Liebhold; Tom Holmes; Brian Leung; Kathy-Fallon Lambert; David A. Orwig; Faith T. Campbell; Jonathan Rosenthal; Deborah G. McCullough; Radka Wildova; Matthew P. Ayres; Charles D. Canham; David R. Foster; Shannon L. LaDeau; Troy Weldy

2016-01-01

We review and synthesize information on invasions of nonnative forest insects and diseases in the United States, including their ecological and economic impacts, pathways of arrival, distribution within the United States, and policy options for reducing future invasions. Nonnative insects have accumulated in United States forests at a rate of ~2.5 per yr over the last...

Non-Native (Exotic) Snake Envenomations in the U.S., 2005–2011

OpenAIRE

Warrick, Brandon J.; Boyer, Leslie V.; Seifert, Steven A.

2014-01-01

Non-native (exotic) snakes are a problematic source of envenomation worldwide. This manuscript describes the current demographics, outcomes and challenges of non-native snakebites in the United States (U.S.). We performed a retrospective case series of the National Poison Data System (NPDS) database between 2005 and 2011. There were 258 human exposures involving at least 61 unique exotic venomous species (average = 37 per year; range = 33–40). Males comprised 79% and females 21%. The averag...

Non-Native University Students' Perception of Plagiarism

Science.gov (United States)

Ahmad, Ummul Khair; Mansourizadeh, Kobra; Ai, Grace Koh Ming

2012-01-01

Plagiarism is a complex issue especially among non-native students and it has received a lot of attention from researchers and scholars of academic writing. Some scholars attribute this problem to cultural perceptions and different attitudes toward texts. This study evaluates student perception of different aspects of plagiarism. A small group of…

Hemispheric asymmetry of emotion words in a non-native mind: a divided visual field study.

Science.gov (United States)

Jończyk, Rafał

2015-05-01

This study investigates hemispheric specialization for emotional words among proficient non-native speakers of English by means of the divided visual field paradigm. The motivation behind the study is to extend the monolingual hemifield research to the non-native context and see how emotion words are processed in a non-native mind. Sixty eight females participated in the study, all highly proficient in English. The stimuli comprised 12 positive nouns, 12 negative nouns, 12 non-emotional nouns and 36 pseudo-words. To examine the lateralization of emotion, stimuli were presented unilaterally in a random fashion for 180 ms in a go/no-go lexical decision task. The perceptual data showed a right hemispheric advantage for processing speed of negative words and a complementary role of the two hemispheres in the recognition accuracy of experimental stimuli. The data indicate that processing of emotion words in non-native language may require greater interhemispheric communication, but at the same time demonstrates a specific role of the right hemisphere in the processing of negative relative to positive valence. The results of the study are discussed in light of the methodological inconsistencies in the hemifield research as well as the non-native context in which the study was conducted.

Nonnative invasive plants: Maintaining biotic and soceioeconomic integrity along the urban-rural-natural gradient

Science.gov (United States)

Cynthia D. Huebner; David J. Nowak; Richard V. Pouyat; Allison R. Bodine

2012-01-01

In this chapter, we evaluate nonnative invasive plant species of the urban-rural-natural area gradient in order to reduce negative impacts of invasive plants on native species and ecosystems. This evaluation includes addressing (i) the concept of urban areas as the primary source of invasive plant species and characteristics of urban nonnative plants, including their...

Residue analysis of sixty pesticides in red swamp crayfish using QuEChERS with high-performance liquid chromatography-tandem mass spectrometry

Science.gov (United States)

In this study, a multi-residue analytical method using QuEChERS extraction and dispersive solid-phase extraction (d-SPE) cleanup followed by high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS) was developed for rapid determination of 60 pesticide residues in whole crayfish a...

Growth strategy, phylogeny and stoichiometry determine the allelopathic potential of native and non-native plants

NARCIS (Netherlands)

Grutters, Bart M.C.; Saccomanno, Benedetta; Gross, Elisabeth M.; Van de Waal, Dedmer B.; van Donk, Ellen; Bakker, Elisabeth S.

2017-01-01

Secondary compounds can contribute to the success of non-native plant species if they reduce damage by native herbivores or inhibit the growth of native plant competitors. However, there is opposing evidence on whether the secondary com- pounds of non-native plant species are stronger than those of

Appropriate Usage Level of Shrimp Waste Meal as Chitin Source for Feeding Young Crayfish (Astacus leptodactylus Esch. 1823

Directory of Open Access Journals (Sweden)

Seval Bahadır Koca*, Nalan Ozgur Yigit, Arife Dulluc, Gonca Erol1, Nihal Cılbız1 and Ramazan Kucukkara1

2011-06-01

Full Text Available This study was conducted to determine effects of shrimp waste meal as natural chitin source at different rates (0 (control, 10, 20, 30 and 40% on growth, feed conversion ratio (FCR, survival of young crayfish (1.61±0.04 g and 3.74±0.03 cm for 60 days. Fifteen glass aquariums (70x30x40 cm were used in the experiment and 20 individuals were stocked per aquarium (95/m2. The highest of final weight and weight gain were obtained in feed with 10% shrimp waste meal group (3.29±0.23 and 1.66±0.23 g, while the lowest of final weight and weight gain was obtained in fed with 40% shrimp waste meal group (2.75±0.35 and 1.18±0.37 g, respectively. However, non-significant differences were found between final weight, weight gain, specific growth rate, final total length, feed conversion ratio, survival percentage among groups at the end of experimental period. It was concluded that shrimp waste meal as natural chitin source can be used in young crayfish diets up to 40% without adverse effect influence on growth.

Mitotic karyotype of the tropical freshwater crayfish Procambarus (Austrocambarus llamasi (Decapoda: Cambaridae

Directory of Open Access Journals (Sweden)

Jeane R Indy

2010-06-01

Full Text Available In Mexico, the biology of Procambarus has been more studied than the biology of other Cambarids because of its diversity and potential use in aquaculture. We determined the karyotype of the Mexican tropical freshwater crayfish Procambarus (Austrocambarus llamasi from 189 metaphase spreads from gill tissues of 17 adults. They had 98-120 chromosomes (mode 2n=120 chromosomes. There are 60 pairs of monoarm, telocentric chromosomes. Sex chromosomes were not detected and we propose that the P. llamasi karyotype can be used to distinguish this species from other Mexican crayfish. Additionally, we suggest using karyological data in aquaculture and conservation biology. Rev. Biol. Trop. 58 (2: 655-662. Epub 2010 June 02.El género Procambarus ha recibido mayor atención en los estudios de los principios fundamentales de su biología debido a su diversidad en el territorio mexicano y potencial uso en acuicultura. El cariotipo típico del acocil tropical mexicano Procambarus (Austrocambarus llamasi, se estudió mediante 189 dispersiones cromosómicas en metafase del tejido branquial de 17 adultos tratados con la técnica citológica de inmersión. Encontramos un amplio número de cromosomas, que variaron entre 98-120 elementos cromosómicos, con número modal diploide de 2n=120 elementos cromosómicos. El cariotipo del acocil tropical esta constituido por 60 pares de cromosomas monorrámeos, todos los centrómero están en la región telocéntrica de los cromosomas. En las metafases mitóticas de hembras y machos no fueron identificados cromosomas sexuales. Sugerimos considerar la estructura cromosómica del cariotipo como una herramienta citotaxonómica así como el empleo de datos cariológicos para propósitos de acuicultura y conservación del acocil tropical.

Non-native salmonids affect amphibian occupancy at multiple spatial scales

Science.gov (United States)

Pilliod, David S.; Hossack, Blake R.; Bahls, Peter F.; Bull, Evelyn L.; Corn, Paul Stephen; Hokit, Grant; Maxell, Bryce A.; Munger, James C.; Wyrick, Aimee

2010-01-01

Aim The introduction of non-native species into aquatic environments has been linked with local extinctions and altered distributions of native species. We investigated the effect of non-native salmonids on the occupancy of two native amphibians, the long-toed salamander (Ambystoma macrodactylum) and Columbia spotted frog (Rana luteiventris), across three spatial scales: water bodies, small catchments and large catchments. Location Mountain lakes at ≥ 1500 m elevation were surveyed across the northern Rocky Mountains, USA. Methods We surveyed 2267 water bodies for amphibian occupancy (based on evidence of reproduction) and fish presence between 1986 and 2002 and modelled the probability of amphibian occupancy at each spatial scale in relation to habitat availability and quality and fish presence. Results After accounting for habitat features, we estimated that A. macrodactylum was 2.3 times more likely to breed in fishless water bodies than in water bodies with fish. Ambystoma macrodactylum also was more likely to occupy small catchments where none of the water bodies contained fish than in catchments where at least one water body contained fish. However, the probability of salamander occupancy in small catchments was also influenced by habitat availability (i.e. the number of water bodies within a catchment) and suitability of remaining fishless water bodies. We found no relationship between fish presence and salamander occupancy at the large-catchment scale, probably because of increased habitat availability. In contrast to A. macrodactylum, we found no relationship between fish presence and R. luteiventris occupancy at any scale. Main conclusions Our results suggest that the negative effects of non-native salmonids can extend beyond the boundaries of individual water bodies and increase A. macrodactylum extinction risk at landscape scales. We suspect that niche overlap between non-native fish and A. macrodactylum at higher elevations in the northern Rocky

I think (that something’s missing: Complementizer deletion in nonnative e-mails

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Mercedes Durham

2011-10-01

Full Text Available Sociolinguistic competence is not often examined in nonnative English acquisition. This is particularly true for features where the variants are neither stylistically nor socially constrained, but rather are acceptable in all circumstances. Learning to use a language fully, however, implies being able to deal with this type of ‘difficulty,’ and understanding what type of variable features nonnative speakers acquire with ease and which ones they do not may help us better understand more general processes of second language acquisition. By comparing the rates of complementizer deletion of nonnative to native speakers and examining their distributions across various internal and external factors, this paper addresses these issues and offers an example of acquisition of what is, in some ways, an invisible variant. Furthermore, by focusing on a Swiss student association, the paper is also able to compare the patterns of French, German and Italian native speakers, to examine to what extent they differ in English.

Status and management of non-native plant invasion in three of the largest national parks in the United States

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Scott Abella

2015-06-01

Full Text Available Globally, invasion by non-native plants threatens resources that nature reserves are designated to protect. We assessed the status of non-native plant invasion on 1,662, 0.1-ha plots in Death Valley National Park, Mojave National Preserve, and Lake Mead National Recreation Area. These parks comprise 2.5 million ha, 23% of the national park land in the contiguous USA. At least one non-native species inhabited 82% of plots. Thirty-one percent of plots contained one non-native species, 30% two, 17% three, and 4% four to ten non-native species. Red brome (Bromus rubens, an ‘ecosystem engineer’ that alters fire regimes, was most widespread, infesting 60% of plots. By identifying frequency of species through this assessment, early detection and treatment can target infrequent species or minimally invaded sites, while containment strategies could focus on established invaders. We further compared two existing systems for prioritizing species for management and found that a third of species on plots had no rankings available. Moreover, rankings did not always agree between ranking systems for species that were ranked. Presence of multiple non-native species complicates treatment, and while we found that 40% of plots contained both forb and grass invaders, exploiting accelerated phenology of non-natives (compared to native annuals might help manage multi-species invasions. Large sizes of these parks and scale of invasion are formidable challenges for management. Yet, precisely because of their size, these reserves represent opportunities to conserve large landscapes of native species by managing non-native plant invasions.

Red swamp crayfish: biology, ecology and invasion - an overview

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Tainã Gonçalves Loureiro

Full Text Available ABSTRACTAlien species have been transported and traded by humans for many centuries. However, with the era of globalization, biological invasions have reached notable magnitudes. Currently, introduction of alien species is one of the major threats to biodiversity and ecosystem functioning. The North American crayfish Procambarus clarkii is one of the most widely introduced freshwater species in the world, especially due to its high economic importance. It is responsible for great modifications in invaded environments causing irreparable ecological and economic damages. Its impressive ability to successfully colonize a wide range of environments is a consequence of its behavioural and biological characteristics that can adapt to features of the invaded location, conferring to this species a notable ecological plasticity. This review summarizes the available information regarding P. clarkii's biology and invasive dynamics around the world in order to contribute to the understanding of the threats posed by its establishment, as well as to support management and impact mitigation efforts.

Environmental niche separation between native and non-native benthic invertebrate species: Case study of the northern Baltic Sea.

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Jänes, Holger; Herkül, Kristjan; Kotta, Jonne

2017-10-01

Knowledge and understanding of geographic distributions of species is crucial for many aspects in ecology, conservation, policy making and management. In order to reach such an understanding, it is important to know abiotic variables that impact and drive distributions of native and non-native species. We used an existing long-term macrobenthos database for species presence-absence information and biomass estimates at different environmental gradients in the northern Baltic Sea. Region specific abiotic variables (e.g. salinity, depth) were derived from previously constructed bathymetric and hydrodynamic models. Multidimensional ordination techniques were then applied to investigate potential niche space separation between all native and non-native invertebrates in the northern Baltic Sea. Such an approach allowed to obtain data rich and robust estimates of the current native and non-native species distributions and outline important abiotic parameters influencing the observed pattern. The results showed clear niche space separation between native and non-native species. Non-native species were situated in an environmental space characterized by reduced salinity, high temperatures, high proportion of soft seabed and decreased depth and wave exposure whereas native species displayed an opposite pattern. Different placement of native and non-native species along the studied environmental niche space is likely to be explained by the differences in their evolutionary history, human mediated activities and geological youth of the Baltic Sea. The results of this study can provide early warnings and effectively outline coastal areas in the northern Baltic Sea that are prone to further range expansion of non-native species as climate change is expected to significantly reduce salinity and increase temperature in wide coastal areas, both supporting the disappearance of native and appearance of non-native species. Copyright © 2017 Elsevier Ltd. All rights reserved.

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

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Justin S Strong

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

Lunar-Rhythmic Molting in Laboratory Populations of the Noble Crayfish Astacus astacus (Crustacea, Astacidea): An Experimental Analysis

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Franke, Robert; Hoerstgen-Schwark, Gabriele

2013-01-01

Juvenile noble crayfish, Astacusastacus (Crustacea, Astacidea) in the second year of age were kept in the laboratory for a twelve-month period under continuing “summer conditions” (LD 16:8, 19°C). Molting processes in this population could be synchronized by artificial moonlight cycles. Peaks of exuviations occurred at “new moons”. Males showed a slightly higher degree of synchronization than females. A phase-shift of the artificial lunar cycle in relation to the natural cycle resulted in a corresponding shift of the molting cycle. This clearly demonstrates that changes in the nocturnal light regime provide the primary external information for the lunar-monthly molting rhythm. There is a first indication that lunar photic stimuli do not act directly but as a zeitgeber which entrains an endogenous molting rhythm to the lunar cycle. Moreover, the results of the long-term experiments suggest that the hibernal resting period of A . astacus in the field (no molts between October and April) may also involve some endogenous programming. Continuing artificial summer conditions can delay but not completely suppress this resting period. The adaptive significance of the phenomena and how the findings may be applied to improve the management of crowded crayfish stocks are discussed. PMID:23840899

Comparison of root-associated communities of native and non-native ectomycorrhizal hosts in an urban landscape.

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Lothamer, K; Brown, S P; Mattox, J D; Jumpponen, A

2014-05-01

Non-native tree species are often used as ornamentals in urban landscapes. However, their root-associated fungal communities remain yet to be examined in detail. Here, we compared richness, diversity and community composition of ectomycorrhizosphere fungi in general and ectomycorrhizal (EcM) fungi in particular between a non-native Pinus nigra and a native Quercus macrocarpa across a growing season in urban parks using 454-pyrosequencing. Our data show that, while the ectomycorrhizosphere community richness and diversity did not differ between the two host, the EcM communities associated with the native host were often more species rich and included more exclusive members than those of the non-native hosts. In contrast, the ectomycorrhizosphere communities of the two hosts were compositionally clearly distinct in nonmetric multidimensional ordination analyses, whereas the EcM communities were only marginally so. Taken together, our data suggest EcM communities with broad host compatibilities and with a limited numbers of taxa with preference to the non-native host. Furthermore, many common fungi in the non-native Pinus were not EcM taxa, suggesting that the fungal communities of the non-native host may be enriched in non-mycorrhizal fungi at the cost of the EcM taxa. Finally, while our colonization estimates did not suggest a shortage in EcM inoculum for either host in urban parks, the differences in the fungi associated with the two hosts emphasize the importance of using native hosts in urban environments as a tool to conserve endemic fungal diversity and richness in man-made systems.

Do environmental changes or juvenile competition act as mechanisms of species displacement in crayfishes?

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Westhoff, Jacob T.; DiStefano, R.J.; Magoulick, D.D.

2012-01-01

The Big Creek Crayfish, Orconectes peruncus, is native to the St. Francis River drainage in Missouri, USA and is often absent where the introduced Woodland Crayfish, Orconectes hylas, has established. We performed a field experiment to determine whether effects of current abiotic conditions and interspecific competition with O. hylas were responsible for displacement of O. peruncus from parts of their former range. We examined growth and survival of juvenile male O. peruncus exposed to juvenile male O. hylas in enclosures at two sites in the former range of O. peruncus. Enclosures contained 8 (low density) or 16 individuals (high density) and had O. peruncus only (control) or both species (interspecific treatment). Juvenile O. peruncus were able to survive and grow in portions of their former range, implicating biotic versus abiotic factors in the displacement of O. peruncus. Survival rates of O. peruncus did not differ among treatments at either site. Orconectes peruncus showed significant growth in all treatments and interspecific effects were not greater than intraspecific effects on O. peruncus growth rates. High-density treatments showed significantly reduced O. peruncus growth rates compared to low-density treatments, except in Carver Creek interspecific treatments. When considered in the context of previous studies examining the effects of O. hylas on O. peruncus, results suggest that neither direct competition between juvenile males of the two species or abiotic change are responsible for the decreased range of O. peruncus. Additional research is required to determine the mechanism(s) driving the displacement of O. peruncus. ?? 2011 Springer Science+Business Media B.V.

Emergence of category-level sensitivities in non-native speech sound learning

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Emily eMyers

2014-08-01

Full Text Available Over the course of development, speech sounds that are contrastive in one’s native language tend to become perceived categorically: that is, listeners are unaware of variation within phonetic categories while showing excellent sensitivity to speech sounds that span linguistically meaningful phonetic category boundaries. The end stage of this developmental process is that the perceptual systems that handle acoustic-phonetic information show special tuning to native language contrasts, and as such, category-level information appears to be present at even fairly low levels of the neural processing stream. Research on adults acquiring non-native speech categories offers an avenue for investigating the interplay of category-level information and perceptual sensitivities to these sounds as speech categories emerge. In particular, one can observe the neural changes that unfold as listeners learn not only to perceive acoustic distinctions that mark non-native speech sound contrasts, but also to map these distinctions onto category-level representations. An emergent literature on the neural basis of novel and non-native speech sound learning offers new insight into this question. In this review, I will examine this literature in order to answer two key questions. First, where in the neural pathway does sensitivity to category-level phonetic information first emerge over the trajectory of speech sound learning? Second, how do frontal and temporal brain areas work in concert over the course of non-native speech sound learning? Finally, in the context of this literature I will describe a model of speech sound learning in which rapidly-adapting access to categorical information in the frontal lobes modulates the sensitivity of stable, slowly-adapting responses in the temporal lobes.

Native Speakers' Perception of Non-Native English Speech

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Jaber, Maysa; Hussein, Riyad F.

2011-01-01

This study is aimed at investigating the rating and intelligibility of different non-native varieties of English, namely French English, Japanese English and Jordanian English by native English speakers and their attitudes towards these foreign accents. To achieve the goals of this study, the researchers used a web-based questionnaire which…

An invasion risk map for non-native aquatic macrophytes of the Iberian Peninsula

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Argantonio Rodríguez-Merino

2017-05-01

Full Text Available Freshwater systems are particularly susceptible to non-native organisms, owing to their high sensitivity to the impacts that are caused by these organisms. Species distribution models, which are based on both environmental and socio-economic variables, facilitate the identification of the most vulnerable areas for the spread of non-native species. We used MaxEnt to predict the potential distribution of 20 non-native aquatic macrophytes in the Iberian Peninsula. Some selected variables, such as the temperature seasonality and the precipitation in the driest quarter, highlight the importance of the climate on their distribution. Notably, the human influence in the territory appears as a key variable in the distribution of studied species. The model discriminated between favorable and unfavorable areas with high accuracy. We used the model to build an invasion risk map of aquatic macrophytes for the Iberian Peninsula that included results from 20 individual models. It showed that the most vulnerable areas are located near to the sea, the major rivers basins, and the high population density areas. These facts suggest the importance of the human impact on the colonization and distribution of non-native aquatic macrophytes in the Iberian Peninsula, and more precisely agricultural development during the Green Revolution at the end of the 70’s. Our work also emphasizes the utility of species distribution models for the prevention and management of biological invasions.

Higher dropout rate in non-native patients than in native patients in rehabilitation in The Netherlands

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Sloots, Maurits; Scheppers, Emmanuel F.; van de Weg, Frans B.; Bartels, Edien A.; Geertzen, Jan H.; Dekker, Joost; Dekker, Jaap

Dropout from a rehabilitation programme often occurs in patients with chronic nonspecific low back pain of non-native origin. However, the exact dropout rate is not known. The objective of this study was to determine the difference in dropout rate between native and non-native patients with chronic

The Spread of Non-native Plant Species Collection of Cibodas Botanical Garden into Mt. Gede Pangrango National Park

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Musyarofah Zuhri

2013-05-01

Full Text Available The role of botanic garden in spread of non-native plant species has concerned of international worldwide. This study aimed to study the extent of non-native plant species from Cibodas Botanical Garden (CBG which invades into natural rainforest. A line transect was made edge-to-interior with 1,600 m in distance from CBG boundary. Result showed that distance from CBG was not significant in correlation with non-native tree and treelet density. Furthermore, presence of existing CBG’s plant collection was not a single aspect which influenced presence and abundance. Three invasive species possibly was escape from CBG and it showed edge-to-interior in stems density, i.e. Cinchona pubescens, Calliandra calothyrsus and Cestrum aurantiacum. The patterns of non-native species were influenced by presence of ditch across transect, existence of human trail, and the other non-native species did not have general pattern of spread distribution. Overall, botanical gardens should minimize the risk of unintentional introduced plant by perform site-specific risk assessment.

CRAYFISH PREDATION EXPERIMENTS ON THE INTRODUCED ZEBRA MUSSEL, DREISSENA POLYMORPHA, IN IRELAND, AND THEIR POTENTIAL FOR BIOCONTROL.

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REYNOLDS J. D.; DONOHOE R.

2001-01-01

The zebra mussel Dreissena polymorpha, native to the Aralo-Caspian region, has spread across Europe in the last 180 years. Although it reached England in 1820, it only arrived in Ireland in around 1995, probably attached to the hull of pleasure boats, and since then has spread through the lowland Shannon and Erne systems, which are linked by canal. While White-clawed crayfish Austropotamobius pallipes (Lereboullet) occur in these systems, Dreissena has not yet colonized sites with large crayf...

Lexical competition in nonnative speech comprehension.

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FitzPatrick, Ian; Indefrey, Peter

2010-06-01

Electrophysiological studies consistently find N400 effects of semantic incongruity in nonnative (L2) language comprehension. These N400 effects are often delayed compared with native (L1) comprehension, suggesting that semantic integration in one's second language occurs later than in one's first language. In this study, we investigated whether such a delay could be attributed to (1) intralingual lexical competition and/or (2) interlingual lexical competition. We recorded EEG from Dutch-English bilinguals who listened to English (L2) sentences in which the sentence-final word was (a) semantically fitting and (b) semantically incongruent or semantically incongruent but initially congruent due to sharing initial phonemes with (c) the most probable sentence completion within the L2 or (d) the L1 translation equivalent of the most probable sentence completion. We found an N400 effect in each of the semantically incongruent conditions. This N400 effect was significantly delayed to L2 words but not to L1 translation equivalents that were initially congruent with the sentence context. Taken together, these findings firstly demonstrate that semantic integration in nonnative listening can start based on word initial phonemes (i.e., before a single lexical candidate could have been selected based on the input) and secondly suggest that spuriously elicited L1 lexical candidates are not available for semantic integration in L2 speech comprehension.

Novel Insights into Antiviral Gene Regulation of Red Swamp Crayfish, Procambarus clarkii, Infected with White Spot Syndrome Virus

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Shaokui Yi

2017-11-01

Full Text Available White spot syndrome virus (WSSV, one of the major pathogens of Procambarus clarkii, has caused severe disruption to the aquaculture industry of P. clarkii in China. To reveal the gene regulatory mechanisms underlying WSSV infection, a comparative transcriptome analysis was performed among WSSV-infected susceptible individuals (GS, viral resistant individuals (GR, and a non-infected control group (GC. A total of 61,349 unigenes were assembled from nine libraries. Subsequently, 515 and 1033 unigenes exhibited significant differential expression in sensitive and resistant crayfish individuals compared to the control group (GC. Many differentially expressed genes (e.g., C-type lectin 4, Peroxinectin, Prophenoloxidase, and Serine/threonine-protein kinase observed in GR and GS play critical roles in pathogen recognition and viral defense reactions after WSSV infection. Importantly, the glycosaminoglycan biosynthesis-chondroitin sulfate/dermatan sulfate pathway was identified to play critical roles in defense to WSSV infection for resistant crayfish individuals by upregulating the chondroitin sulfate related genes for the synthesis of WSSV-sensitive, functional chondroitin sulfate chains containing E units. Numerous genes and the key pathways identified between resistant and susceptible P. clarkii individuals provide valuable insights regarding antiviral response mechanisms of decapoda species and may help to improve the selective breeding of P. clarkii WSSV-resistance.

Tracking the invasion of the red swamp crayfish Procambarus clarkii (Girard, 1852 (Decapoda Cambaridae in Sicily: a “citizen science” approach

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Francesco Paolo Faraone

2017-11-01

Full Text Available The first record of the red swamp crayfish in Sicily dates back to 2003 and, since then, the species seemed to be confined to a few localities in western Sicily. A small “citizen science” project carried out from November 2016 onwards led to the creation of the “Sicilian Procambarus working group” (SPwg, which aims at monitoring the distribution and impact of the species in Sicily. To date, the SPwg found the red swamp crayfish in five new sites on the island, thus doubling the number of local sites of occurrence. The new Procambarus clarkii sites lie in different river basins, some of them located several hundred kilometres from the invaded areas known to date, suggesting the existence of multiple independent releases of the species in the wild. The need of better informing the local population on the risks exerted by invasive species on biological diversity, and of carefully monitoring the impact of P. clarkii on the Sicilian inland water biota is briefly stressed.

Landscape genetics of the nonnative red fox of California.

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Sacks, Benjamin N; Brazeal, Jennifer L; Lewis, Jeffrey C

2016-07-01

Invasive mammalian carnivores contribute disproportionately to declines in global biodiversity. In California, nonnative red foxes (Vulpes vulpes) have significantly impacted endangered ground-nesting birds and native canids. These foxes derive primarily from captive-reared animals associated with the fur-farming industry. Over the past five decades, the cumulative area occupied by nonnative red fox increased to cover much of central and southern California. We used a landscape-genetic approach involving mitochondrial DNA (mtDNA) sequences and 13 microsatellites of 402 nonnative red foxes removed in predator control programs to investigate source populations, contemporary connectivity, and metapopulation dynamics. Both markers indicated high population structuring consistent with origins from multiple introductions and low subsequent gene flow. Landscape-genetic modeling indicated that population connectivity was especially low among coastal sampling sites surrounded by mountainous wildlands but somewhat higher through topographically flat, urban and agricultural landscapes. The genetic composition of populations tended to be stable for multiple generations, indicating a degree of demographic resilience to predator removal programs. However, in two sites where intensive predator control reduced fox abundance, we observed increases in immigration, suggesting potential for recolonization to counter eradication attempts. These findings, along with continued genetic monitoring, can help guide localized management of foxes by identifying points of introductions and routes of spread and evaluating the relative importance of reproduction and immigration in maintaining populations. More generally, the study illustrates the utility of a landscape-genetic approach for understanding invasion dynamics and metapopulation structure of one of the world's most destructive invasive mammals, the red fox.

Phytophagous insects on native and non-native host plants: combining the community approach and the biogeographical approach.

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Kim Meijer

Full Text Available During the past centuries, humans have introduced many plant species in areas where they do not naturally occur. Some of these species establish populations and in some cases become invasive, causing economic and ecological damage. Which factors determine the success of non-native plants is still incompletely understood, but the absence of natural enemies in the invaded area (Enemy Release Hypothesis; ERH is one of the most popular explanations. One of the predictions of the ERH, a reduced herbivore load on non-native plants compared with native ones, has been repeatedly tested. However, many studies have either used a community approach (sampling from native and non-native species in the same community or a biogeographical approach (sampling from the same plant species in areas where it is native and where it is non-native. Either method can sometimes lead to inconclusive results. To resolve this, we here add to the small number of studies that combine both approaches. We do so in a single study of insect herbivory on 47 woody plant species (trees, shrubs, and vines in the Netherlands and Japan. We find higher herbivore diversity, higher herbivore load and more herbivory on native plants than on non-native plants, generating support for the enemy release hypothesis.

Nonnative plant response to silvicultural treatments: A model based on disturbance, propagule pressure, and competitive abilities

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Steve Sutherland; Cara R. Nelson

2010-01-01

Invasion by nonnative plants can result in substantial adverse effects on the functions of native forest ecosystems, including nutrient cycling and fire regimes. Thus, forest managers need to be aware of the potential impacts of management activities, including silvicultural treatments, on nonnative vegetation. To aid in that effort, we created a conceptual model of...

Memory for non-native language: the role of lexical processing in the retention of surface form.

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Sampaio, Cristina; Konopka, Agnieszka E

2013-01-01

Research on memory for native language (L1) has consistently shown that retention of surface form is inferior to that of gist (e.g., Sachs, 1967). This paper investigates whether the same pattern is found in memory for non-native language (L2). We apply a model of bilingual word processing to more complex linguistic structures and predict that memory for L2 sentences ought to contain more surface information than L1 sentences. Native and non-native speakers of English were tested on a set of sentence pairs with different surface forms but the same meaning (e.g., "The bullet hit/struck the bull's eye"). Memory for these sentences was assessed with a cued recall procedure. Responses showed that native and non-native speakers did not differ in the accuracy of gist-based recall but that non-native speakers outperformed native speakers in the retention of surface form. The results suggest that L2 processing involves more intensive encoding of lexical level information than L1 processing.

A Hybrid Acoustic and Pronunciation Model Adaptation Approach for Non-native Speech Recognition

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Oh, Yoo Rhee; Kim, Hong Kook

In this paper, we propose a hybrid model adaptation approach in which pronunciation and acoustic models are adapted by incorporating the pronunciation and acoustic variabilities of non-native speech in order to improve the performance of non-native automatic speech recognition (ASR). Specifically, the proposed hybrid model adaptation can be performed at either the state-tying or triphone-modeling level, depending at which acoustic model adaptation is performed. In both methods, we first analyze the pronunciation variant rules of non-native speakers and then classify each rule as either a pronunciation variant or an acoustic variant. The state-tying level hybrid method then adapts pronunciation models and acoustic models by accommodating the pronunciation variants in the pronunciation dictionary and by clustering the states of triphone acoustic models using the acoustic variants, respectively. On the other hand, the triphone-modeling level hybrid method initially adapts pronunciation models in the same way as in the state-tying level hybrid method; however, for the acoustic model adaptation, the triphone acoustic models are then re-estimated based on the adapted pronunciation models and the states of the re-estimated triphone acoustic models are clustered using the acoustic variants. From the Korean-spoken English speech recognition experiments, it is shown that ASR systems employing the state-tying and triphone-modeling level adaptation methods can relatively reduce the average word error rates (WERs) by 17.1% and 22.1% for non-native speech, respectively, when compared to a baseline ASR system.

Seed rain under native and non-native tree species in the Cabo Rojo National Wildlife Refuge, Puerto Rico.

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Arias Garcia, Andrea; Chinea, J Danilo

2014-09-01

Seed dispersal is a fundamental process in plant ecology and is of critical importance for the restoration of tropical communities. The lands of the Cabo Rojo National Wildlife Refuge (CRNWR), formerly under agriculture, were abandoned in the 1970s and colonized mainly by non-native tree species of degraded pastures. Here we described the seed rain under the most common native and non-native trees in the refuge in an attempt to determine if focal tree geographic origin (native versus non-native) influences seed dispersal. For this, seed rain was sampled for one year under the canopies of four native and four non-native tree species common in this refuge using 40 seed traps. No significant differences were found for the abundance of seeds, or their diversity, dispersing under native versus non-native focal tree species, nor under the different tree species. A significantly different seed species composition was observed reaching native versus non-native focal species. However, this last result could be more easily explained as a function of distance of the closest adults of the two most abundantly dispersed plant species to the seed traps than as a function of the geographic origin of the focal species. We suggest to continue the practice of planting native tree species, not only as a way to restore the community to a condition similar to the original one, but also to reduce the distances needed for effective dispersal.

Ectomycorrhizal fungal communities of native and non-native Pinus and Quercus species in a common garden of 35-year-old trees.

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Trocha, Lidia K; Kałucka, Izabela; Stasińska, Małgorzata; Nowak, Witold; Dabert, Mirosława; Leski, Tomasz; Rudawska, Maria; Oleksyn, Jacek

2012-02-01

Non-native tree species have been widely planted or have become naturalized in most forested landscapes. It is not clear if native trees species collectively differ in ectomycorrhizal fungal (EMF) diversity and communities from that of non-native tree species. Alternatively, EMF species community similarity may be more determined by host plant phylogeny than by whether the plant is native or non-native. We examined these unknowns by comparing two genera, native and non-native Quercus robur and Quercus rubra and native and non-native Pinus sylvestris and Pinus nigra in a 35-year-old common garden in Poland. Using molecular and morphological approaches, we identified EMF species from ectomycorrhizal root tips and sporocarps collected in the monoculture tree plots. A total of 69 EMF species were found, with 38 species collected only as sporocarps, 18 only as ectomycorrhizas, and 13 both as ectomycorrhizas and sporocarps. The EMF species observed were all native and commonly associated with a Holarctic range in distribution. We found that native Q. robur had ca. 120% higher total EMF species richness than the non-native Q. rubra, while native P. sylvestris had ca. 25% lower total EMF species richness than non-native P. nigra. Thus, across genera, there was no evidence that native species have higher EMF species diversity than exotic species. In addition, we found a higher similarity in EMF communities between the two Pinus species than between the two Quercus species. These results support the naturalization of non-native trees by means of mutualistic associations with cosmopolitan and novel fungi.

Determination of mercury by cold-vapor technique in several tissues of treated American red crayfish (Procambarus clarkii)

Energy Technology Data Exchange (ETDEWEB)

Del Ramo, J.; Pastor, A.; Diaz-Mayans, J.; Medina, J.; Torreblanca, A.

1988-01-01

Adult intermolt specimens of American red crayfish (Procambarus clarkii) collected from Lake Albufera (Valencia, Spain), were exposed to mercury during 96 h. The Hg-concentrations used were 50, 100, and 250 ..mu..g Hg/l as Cl/sub 2/Hg. The content of mercury in muscle, midgut gland, antennal glands and gills was investigated. Determinations of mercury were made by cold-vapor technique and AAS. The mercury levels in all examined tissues increased significantly with increasing Hg-concentration in the water.

Effect of calcium on excitatory neuromuscular transmission in the crayfish

Science.gov (United States)

Bracho, H.; Orkand, R. K.

1970-01-01

1. The effects of varying the external Ca concentration from 1·8 to 30 mM/l. (⅛-2 times normal) have been studied at the in vitro crayfish excitatory neuromuscular junction. Electrophysiological techniques were used to record transmembrane junctional potentials from muscle fibres and extracellular junctional currents from the vicinity of nerve terminals. 2. The excitatory junctional potential amplitude was proportional to [Ca]0n, where n varied between 0·68 and 0·94 (mean 0·82) when [Ca]0 was varied from 1·8 to 15 mM/l. 3. The increase in junctional potential amplitude on raising [Ca]0 resulted primarily from an increase in the average number of quanta of excitatory transmitter released from the presynaptic nerve terminal by the nerve impulse. 4. The size of the quanta, synaptic delay, presynaptic potential and electrical properties of the muscle membrane were little affected by changes in calcium concentration in the range studied. PMID:5498460

Potential population and assemblage influences of non-native trout on native nongame fish in Nebraska headwater streams

Science.gov (United States)

Turek, Kelly C.; Pegg, Mark A.; Pope, Kevin L.; Schainost, Steve

2014-01-01

Non-native trout are currently stocked to support recreational fisheries in headwater streams throughout Nebraska. The influence of non-native trout introductions on native fish populations and their role in structuring fish assemblages in these systems is unknown. The objectives of this study were to determine (i) if the size structure or relative abundance of native fish differs in the presence and absence of non-native trout, (ii) if native fish-assemblage structure differs in the presence and absence of non-native trout and (iii) if native fish-assemblage structure differs across a gradient in abundances of non-native trout. Longnose dace Rhinichthys cataractae were larger in the presence of brown trout Salmo trutta and smaller in the presence of rainbow trout Oncorhynchus mykiss compared to sites without trout. There was also a greater proportion of larger white suckers Catostomus commersonii in the presence of brown trout. Creek chub Semotilus atromaculatus and fathead minnow Pimephales promelas size structures were similar in the presence and absence of trout. Relative abundances of longnose dace, white sucker, creek chub and fathead minnow were similar in the presence and absence of trout, but there was greater distinction in native fish-assemblage structure between sites with trout compared to sites without trout as trout abundances increased. These results suggest increased risk to native fish assemblages in sites with high abundances of trout. However, more research is needed to determine the role of non-native trout in structuring native fish assemblages in streams, and the mechanisms through which introduced trout may influence native fish populations.

The online application of binding condition B in native and non-native pronoun resolution

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Clare ePatterson

2014-02-01

Full Text Available Previous research has shown that anaphor resolution in a non-native language may be more vulnerable to interference from structurally inappropriate antecedents compared to native anaphor resolution. To test whether previous findings on reflexive anaphors generalise to non-reflexive pronouns, we carried out an eye-movement monitoring study investigating the application of binding condition B during native and non-native sentence processing. In two online reading experiments we examined when during processing local and/or non-local antecedents for pronouns were considered in different types of syntactic environment. Our results demonstrate that both native English speakers and native German-speaking learners of English showed online sensitivity to binding condition B in that they did not consider syntactically inappropriate antecedents. For pronouns thought to be exempt from condition B (so-called 'short-distance pronouns', the native readers showed a weak preference for the local antecedent during processing. The non-native readers, on the other hand, showed a preference for the matrix subject even where local coreference was permitted, and despite demonstrating awareness of short-distance pronouns' referential ambiguity in a complementary offline task. This indicates that non-native comprehenders are less sensitive during processing to structural cues that render pronouns exempt from condition B, and prefer to link a pronoun to a salient subject antecedent instead.

Catalytic mechanism of phenylacetone monooxygenases for non-native linear substrates.

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Carvalho, Alexandra T P; Dourado, Daniel F A R; Skvortsov, Timofey; de Abreu, Miguel; Ferguson, Lyndsey J; Quinn, Derek J; Moody, Thomas S; Huang, Meilan

2017-10-11

Phenylacetone monooxygenase (PAMO) is the most stable and thermo-tolerant member of the Baeyer-Villiger monooxygenase family, and therefore it is an ideal candidate for the synthesis of industrially relevant compounds. However, its limited substrate scope has largely limited its industrial applications. In the present work, we provide, for the first time, the catalytic mechanism of PAMO for the native substrate phenylacetone as well as for a linear non-native substrate 2-octanone, using molecular dynamics simulations, quantum mechanics and quantum mechanics/molecular mechanics calculations. We provide a theoretical basis for the preference of the enzyme for the native aromatic substrate over non-native linear substrates. Our study provides fundamental atomic-level insights that can be employed in the rational engineering of PAMO for wide applications in industrial biocatalysis, in particular, in the biotransformation of long-chain aliphatic oils into potential biodiesels.

An Investigation of Native and Nonnative English Speakers' Levels of Written Syntactic Complexity in Asynchronous Online Discussions

Science.gov (United States)

Mancilla, Rae L.; Polat, Nihat; Akcay, Ahmet O.

2017-01-01

This manuscript reports on a corpus-based comparison of native and nonnative graduate students' language production in an asynchronous learning environment. Using 486 discussion board postings from a five-year period (2009-2013), we analyzed the extent to which native and nonnative university students' writing differed in 10 measures of syntactic…

Mental health status in pregnancy among native and non-native Swedish-speaking women

DEFF Research Database (Denmark)

Wangel, Anne-Marie; Schei, Berit; Ryding, Elsa Lena

2012-01-01

OBJECTIVES: To describe mental health status in native and non-native Swedish-speaking pregnant women and explore risk factors of depression and posttraumatic stress (PTS) symptoms. DESIGN AND SETTING: A cross-sectional questionnaire study was conducted at midwife-based antenatal clinics in South......OBJECTIVES: To describe mental health status in native and non-native Swedish-speaking pregnant women and explore risk factors of depression and posttraumatic stress (PTS) symptoms. DESIGN AND SETTING: A cross-sectional questionnaire study was conducted at midwife-based antenatal clinics...... in Southern Sweden. SAMPLE: A non-selected group of women in mid-pregnancy. METHODS: Participants completed a questionnaire covering background characteristics, social support, life events, mental health variables and the short Edinburgh Depression Scale. MAIN OUTCOME MEASURES: Depressive symptoms during...... the past week and PTS symptoms during the past year. RESULTS: Out of 1003 women, 21.4% reported another language than Swedish as their mother tongue and were defined as non-native. These women were more likely to be younger, have fewer years of education, potential financial problems, and lack of social...

Growth rate differences between resident native brook trout and non-native brown trout

Science.gov (United States)

Carlson, S.M.; Hendry, A.P.; Letcher, B.H.

2007-01-01

Between species and across season variation in growth was examined by tagging and recapturing individual brook trout Salvelinus fontinalis and brown trout Salmo trutta across seasons in a small stream (West Brook, Massachusetts, U.S.A.). Detailed information on body size and growth are presented to (1) test whether the two species differed in growth within seasons and (2) characterize the seasonal growth patterns for two age classes of each species. Growth differed between species in nearly half of the season- and age-specific comparisons. When growth differed, non-native brown trout grew faster than native brook trout in all but one comparison. Moreover, species differences were most pronounced when overall growth was high during the spring and early summer. These growth differences resulted in size asymmetries that were sustained over the duration of the study. A literature survey also indicated that non-native salmonids typically grow faster than native salmonids when the two occur in sympatry. Taken together, these results suggest that differences in growth are not uncommon for coexisting native and non-native salmonids. ?? 2007 The Authors.

Direct and Indirect Influence of Non-Native Neighbours on Pollination and Fruit Production of a Native Plant.

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Ana Montero-Castaño

Full Text Available Entomophilous non-native plants can directly affect the pollination and reproductive success of native plant species and also indirectly, by altering the composition and abundance of floral resources in the invaded community. Separating direct from indirect effects is critical for understanding the mechanisms underlying the impacts of non-native species on recipient communities.Our aims are: (a to explore both the direct effect of the non-native Hedysarum coronarium and its indirect effect, mediated by the alteration of floral diversity, on the pollinator visitation rate and fructification of the native Leopoldia comosa and (b to distinguish whether the effects of the non-native species were due to its floral display or to its vegetative interactions.We conducted field observations within a flower removal experimental setup (i.e. non-native species present, absent and with its inflorescences removed at the neighbourhood scale.Our study illustrates the complexity of mechanisms involved in the impacts of non-native species on native species. Overall, Hedysarum increased pollinator visitation rates to Leopoldia target plants as a result of direct and indirect effects acting in the same direction. Due to its floral display, Hedysarum exerted a direct magnet effect attracting visits to native target plants, especially those made by the honeybee. Indirectly, Hedysarum also increased the visitation rate of native target plants. Due to the competition for resources mediated by its vegetative parts, it decreased floral diversity in the neighbourhoods, which was negatively related to the visitation rate to native target plants. Hedysarum overall also increased the fructification of Leopoldia target plants, even though such an increase was the result of other indirect effects compensating for the observed negative indirect effect mediated by the decrease of floral diversity.

Non-native grass removal and shade increase soil moisture and seedling performance during Hawaiian dry forest restoration

Science.gov (United States)

Jared M. Thaxton; Susan Cordell; Robert J. Cabin; Darren R. Sandquist

2012-01-01

Invasive non-native species can create especially problematic restoration barriers in subtropical and tropical dry forests. Native dry forests in Hawaii presently cover less than 10% of their original area. Many sites that historically supported dry forest are now completely dominated by non-native species, particularly grasses. Within a grass-dominated site in leeward...

Musical ability and non-native speech-sound processing are linked through sensitivity to pitch and spectral information.

Science.gov (United States)

Kempe, Vera; Bublitz, Dennis; Brooks, Patricia J

2015-05-01

Is the observed link between musical ability and non-native speech-sound processing due to enhanced sensitivity to acoustic features underlying both musical and linguistic processing? To address this question, native English speakers (N = 118) discriminated Norwegian tonal contrasts and Norwegian vowels. Short tones differing in temporal, pitch, and spectral characteristics were used to measure sensitivity to the various acoustic features implicated in musical and speech processing. Musical ability was measured using Gordon's Advanced Measures of Musical Audiation. Results showed that sensitivity to specific acoustic features played a role in non-native speech-sound processing: Controlling for non-verbal intelligence, prior foreign language-learning experience, and sex, sensitivity to pitch and spectral information partially mediated the link between musical ability and discrimination of non-native vowels and lexical tones. The findings suggest that while sensitivity to certain acoustic features partially mediates the relationship between musical ability and non-native speech-sound processing, complex tests of musical ability also tap into other shared mechanisms. © 2014 The British Psychological Society.

Fuzzy Nonnative Phonolexical Representations Lead to Fuzzy Form-to-Meaning Mappings

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Svetlana V Cook

2016-09-01

Full Text Available The present paper explores nonnative (L2 phonological encoding of lexical entries and dissociates the difficulties associated with L2 phonological and phonolexical encoding by focusing on similarly sounding L2 words that are not differentiated by difficult phonological contrasts. We test two main claims of the fuzzy lexicon hypothesis: (1 L2 fuzzy phonolexical representations are not fully specified and lack details at both phonological and phonolexical levels of representation (Experiment 1; and (2 fuzzy phonolexical representations can lead to establishing incorrect form-to-meaning mappings (Experiment 2.The Russian-English Translation Priming task (Experiment 1, TJT explores how the degree of phonolexical similarity between a word and its lexical competitor affects lexical access of Russian words. Words with smaller phonolexical distance (e.g., parent - parrot show longer reaction times and lower accuracy compared to words with a larger phonolexical distance (e.g., parent – parchment in lower-proficiency nonnative speakers, and, to a lesser degree, higher-proficiency speakers. This points to a lack of detail in nonnative phonolexical representations necessary for efficient lexical access. The Russian Pseudo-Semantic Priming task (Experiment 2, PSP addresses the vulnerability of form-to-meaning mappings as a consequence of fuzzy phonolexical representations in L2. We primed the target with a word semantically related to its phonological competitor, or a potentially confusable word. The findings of Experiment 2 extend the results of Experiment 1 that, unlike native speakers, nonnative speakers do not properly encode phonolexical information. As a result, they are prone to access an incorrect lexical representation of a competitor word, as indicated by a slowdown in the judgments to confusable words.The study provides evidence that fuzzy phonolexical representations result in unfaithful form-to-meaning mappings, which lead to retrieval of

Non-native tree species in urban areas of the city of Nitra

International Nuclear Information System (INIS)

Galis, M

2014-01-01

Non-native plant species are part of our environment. The introduction of these species is huge conditioned by anthropogenic activities, such as the urban environment is characterized by. During the field surveys of selected town Nitra (Chrenova, Mikova Ves, Zobor), we studied the frequency of non-native tree species in the contact zone. Overall, we found out the presence of 10 alien species, observed in this area. Our results show dominant presence of the species Rhus typhina, followed by the Robinia pseudoacacia and Ailanthus altissima. Individual plants were tied largely to the surrounding of built-up areas, often growns directly in front of houses, or as a part of urban green. (author)

Exploring the role of wood waste landfills in early detection of non-native alien wood-boring beetles

Science.gov (United States)

Davide Rassati; Massimo Faccoli; Lorenzo Marini; Robert A. Haack; Andrea Battisti; Edoardo. Petrucco Toffolo

2015-01-01

Non-native wood-boring beetles (Coleoptera) represent one of the most commonly intercepted groups of insects at ports worldwide. The development of early detection methods is a crucial step when implementing rapid response programs so that non-native wood-boring beetles can be quickly detected and a timely action plan can be produced. However, due to the limited...

A non-native prey mediates the effects of a shared predator on an ecosystem service.

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James E Byers

Full Text Available Non-native species can alter ecosystem functions performed by native species often by displacing influential native species. However, little is known about how ecosystem functions may be modified by trait-mediated indirect effects of non-native species. Oysters and other reef-associated filter feeders enhance water quality by controlling nutrients and contaminants in many estuarine environments. However, this ecosystem service may be mitigated by predation, competition, or other species interactions, especially when such interactions involve non-native species that share little evolutionary history. We assessed trophic and other interference effects on the critical ecosystem service of water filtration in mesocosm experiments. In single-species trials, typical field densities of oysters (Crassostrea virginica reduced water-column chlorophyll a more strongly than clams (Mercenaria mercenaria. The non-native filter-feeding reef crab Petrolisthes armatus did not draw down chlorophyll a. In multi-species treatments, oysters and clams combined additively to influence chlorophyll a drawdown. Petrolisthes did not affect net filtration when added to the bivalve-only treatments. Addition of the predatory mud crab Panopeus herbstii did not influence oyster feeding rates, but it did stop chlorophyll a drawdown by clams. However, when Petrolisthes was also added in with the clams, the clams filtered at their previously unadulterated rates, possibly because Petrolisthes drew the focus of predators or habituated the clams to crab stimuli. In sum, oysters were the most influential filter feeder, and neither predators nor competitors interfered with their net effect on water-column chlorophyll. In contrast, clams filtered less, but were more sensitive to predators as well as a facilitative buffering effect of Petrolisthes, illustrating that non-native species can indirectly affect an ecosystem service by aiding the performance of a native species.

Introduction of non-native marine fish species to the Canary Islands waters through oil platforms as vectors

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Pajuelo, José G.; González, José A.; Triay-Portella, Raül; Martín, José A.; Ruiz-Díaz, Raquel; Lorenzo, José M.; Luque, Ángel

2016-11-01

This work documents the introduction of non-native fish species to the Canary Islands (central-eastern Atlantic) through oil rigs. Methodological approaches have included surveys by underwater visual censuses around and under oil platforms and along the docking area of rigs at the Port of Las Palmas. Eleven non-native fish species were registered. Paranthias furcifer, Abudefduf hoefleri, Acanthurus bahianus, Acanthurus chirurgus, and Acanthurus coeruleus are first recorded from the Canaries herein. Other three species could not be identified, although they have never been observed in the Canaries. Cephalopholis taeniops, Abudefduf saxatilis, and Acanthurus monroviae had been previously recorded. Native areas of these species coincide with the areas of origin and the scale of oil rigs with destination the Port of Las Palmas. The absence of native species in the censuses at rigs and their presence at rigs docking area, together with the observation of non-native species after the departure of platforms, reject the possibility that these non-native species were already present in the area introduced by another vector. C. taeniops, A. hoefleri, A. saxatilis, A. chirurgus, A. coeruleus and A. monroviae are clearly seafarer species. A. bahianus seems to be a potential seafarer species. P. furcifer is a castaway species. For the moment, the number of individuals of the non-native species in marine ecosystems of the Canaries seems to be low, and more investigation is needed for controlling these translocations.

Non-Native English Teachers' Beliefs on Grammar Instruction

Science.gov (United States)

Önalan, Okan

2018-01-01

Research on teacher cognition, which mainly focuses on identifying what teachers think, know and believe, is essential to understanding teachers' cognitive framework as it relates to the instructional choices they make. The aim of this study is to find out the beliefs of non-native speaker teachers of English on grammar instruction and to explain…

Non-native acylated homoserine lactones reveal that LuxIR quorum sensing promotes symbiont stability

Science.gov (United States)

Ho, Jessica S.; Geske, Grant D.; Blackwell, Helen E.; Ruby, Edward G.

2014-01-01

SUMMARY Quorum sensing, a group behavior coordinated by a diffusible pheromone signal and a cognate receptor, is typical of bacteria that form symbioses with plants and animals. LuxIR-type acyl homoserine-lactone (AHL) quorum sensing is common in Gram-negative proteobacteria, and many members of this group have additional quorum-sensing networks. The bioluminescent symbiont Vibrio fischeri encodes two AHL signal synthases: AinS and LuxI. AinS-dependent quorum sensing converges with LuxI-dependent quorum sensing at the LuxR regulatory element. Both AinS- and LuxI-mediated signaling are required for efficient and persistent colonization of the squid host, Euprymna scolopes. The basis of the mutualism is symbiont bioluminescence, which is regulated by both LuxI- and AinS-dependent quorum sensing, and is essential for maintaining a colonization of the host. Here, we used chemical and genetic approaches to probe the dynamics of LuxI- and AinS-mediated regulation of bioluminescence during symbiosis. We demonstrate that both native AHLs and non-native AHL analogs can be used to non-invasively and specifically modulate induction of symbiotic bioluminescence via LuxI-dependent quorum sensing. Our data suggest that the first day of colonization, during which symbiont bioluminescence is induced by LuxIR, is a critical period that determines the stability of the V. fischeri population once symbiosis is established. PMID:24191970

Optimizing Automatic Speech Recognition for Low-Proficient Non-Native Speakers

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Catia Cucchiarini

2010-01-01

Full Text Available Computer-Assisted Language Learning (CALL applications for improving the oral skills of low-proficient learners have to cope with non-native speech that is particularly challenging. Since unconstrained non-native ASR is still problematic, a possible solution is to elicit constrained responses from the learners. In this paper, we describe experiments aimed at selecting utterances from lists of responses. The first experiment on utterance selection indicates that the decoding process can be improved by optimizing the language model and the acoustic models, thus reducing the utterance error rate from 29–26% to 10–8%. Since giving feedback on incorrectly recognized utterances is confusing, we verify the correctness of the utterance before providing feedback. The results of the second experiment on utterance verification indicate that combining duration-related features with a likelihood ratio (LR yield an equal error rate (EER of 10.3%, which is significantly better than the EER for the other measures in isolation.

Response Function of the Crayfish Caudal Photoreceptor to Hydrodynamic Stimuli

Science.gov (United States)

Breite, Sally; Bahar, Sonya; Neiman, Alexander; Moss, Frank

2002-03-01

In its abdominal 6th ganglion the crayfish houses 2 light-sensitive neurons (caudal photoreceptors, or CPRs). It is known that these neurons work in tandem with a mechanosensory system of tiny hairs spread across the tailfan, which make synaptic contact with the photoreceptors. A stochastic resonance effect has been shown in this system in which light enhances the transduction of a weak, periodic mechanosensory (hydrodynamic) stimulus. It is not known, however, whether an optimal response from the CPR is induced by a single sine wave cycle or some other waveform. We have experimentally investigated this favorable waveform by driving a tailfan preparation with mechanical 10 Hz correlated Ornstein-Uhlenbeck noise and calculating the response function from the spike-triggered average of the applied noise waveform. We will discuss differences in the shape of the optimal waveform under dark and light conditions, as well as what seems to be a noticeable difference in the magnitude of the animals' response to a noisy stimulus in comparison with a periodic stimulus.

Clinical features of Haff disease and myositis after the consumption of boiled brackish water crayfish: a retrospective study of 96 cases at a single centre.

Science.gov (United States)

He, Fei; Ni, Jun; Huang, Jun-Ai; Liu, Yao; Wu, Chao; Wang, Jun

2018-05-08

The present study describes the difference in clinical features between the patients with Haff disease and crayfish-related myositis (CRM) after crayfish consumption. This was a single-centre, retrospective analysis at the Emergency Department of the Drum Tower Hospital of Nanjing University School of Medicine from July to August of 2016. The baseline information came from the Electronic Medical Record System at the institution. Totally 96 patients were included, of whom 52 patients were confirmed to have Haff disease and 44 patients were CRM. The illness predominately occurs in summer and most of them (55/96) are female. The primary clinical features are myalgia, muscle allodynia and back and body pain. Statistical differences in the baseline CK, CK-MB, myoglobin, and the WBC count exist between the Haff disease and CRM groups (P < 0.05). The serum levels of CK and CK-MB increase in the second (a median time 29.2 ± 7.4 h) or third day (a median time 54.8 ± 9.3 h) of disease course, and then rapidly decreased to normal levels, while the levels of myoglobin peak at the admission (a median time 7.7 ± 6.4 h) and became normal after admission. There were no fatalities or complications during this study. All 96 patients recovered in a week. Of them, 75 were followed-up within 1 month and none had recurrence. The Haff disease and CRM after boiled crayfish consumption reflect a different severity of muscle injury, and reveal similar clinical characteristics and most of the laboratory values. The overall prognosis of both is good.

Ecohydrological consequences of non-native riparian vegetation in the southwestern United States: A review from an ecophysiological perspective

Science.gov (United States)

Hultine, K. R.; Bush, S. E.

2011-07-01

Protecting water resources for expanding human enterprise while conserving valued natural habitat is among the greatest challenges of the 21st century. Global change processes such as climate change and intensive land use pose significant threats to water resources, particularly in arid regions where potential evapotranspiration far exceeds annual rainfall. Potentially compounding these shortages is the progressive expansion of non-native plant species in riparian areas along streams, canals and rivers in geographically arid regions. This paper sets out to identify when and where non-native riparian plant species are likely to have the highest potential impact on hydrologic fluxes of arid and semiarid river systems. We develop an ecophysiological framework that focuses on two main criteria: (1) examination of the physiological traits that promote non-native species establishment and persistence across environmental gradients, and (2) assessment of where and to what extent hydrologic fluxes are potentially altered by the establishment of introduced species at varying scales from individual plants, to small river reaches, to entire river basins. We highlight three non-native plant species that currently dominate southwestern United States riparian forests. These include tamarisk (Tamarix spp.), Russian olive (Eleagnus angustifolia), and Russian knapweed (Acroptilon repens). As with other recent reviews, we suspect that in many cases the removal of these, and other non-native species will have little or no impact on either streamflow volume or groundwater levels. However, we identify potential exceptions where the expansion of non-native plant species could have significant impact on ecohydrologic processes associated with southwestern United States river systems. Future research needs are outlined that will ultimately assist land managers and policy makers with restoration and conservation priorities to preserve water resources and valued riparian habitat given

76 FR 79209 - Proposed Safe Harbor Agreement for the Shasta Crayfish in Cassel, Shasta County, CA

Science.gov (United States)

2011-12-21

... nonnative predators and competitors, the Service is working closely with the California Department of Fish... personal identifying information in your comment, you should be aware that your entire comment--including...

Species replacement by a nonnative salmonid alters ecosystem function by reducing prey subsidies that support riparian spiders

Science.gov (United States)

Benjamin, J.R.; Fausch, K.D.; Baxter, C.V.

2011-01-01

Replacement of a native species by a nonnative can have strong effects on ecosystem function, such as altering nutrient cycling or disturbance frequency. Replacements may cause shifts in ecosystem function because nonnatives establish at different biomass, or because they differ from native species in traits like foraging behavior. However, no studies have compared effects of wholesale replacement of a native by a nonnative species on subsidies that support consumers in adjacent habitats, nor quantified the magnitude of these effects. We examined whether streams invaded by nonnative brook trout (Salvelinus fontinalis) in two regions of the Rocky Mountains, USA, produced fewer emerging adult aquatic insects compared to paired streams with native cutthroat trout (Oncorhynchus clarkii), and whether riparian spiders that depend on these prey were less abundant along streams with lower total insect emergence. As predicted, emergence density was 36% lower from streams with the nonnative fish. Biomass of brook trout was higher than the cutthroat trout they replaced, but even after accounting for this difference, emergence was 24% lower from brook trout streams. More riparian spiders were counted along streams with greater total emergence across the water surface. Based on these results, we predicted that brook trout replacement would result in 6-20% fewer spiders in the two regions. When brook trout replace cutthroat trout, they reduce cross-habitat resource subsidies and alter ecosystem function in stream-riparian food webs, not only owing to increased biomass but also because traits apparently differ from native cutthroat trout. ?? 2011 Springer-Verlag.

Understanding the threats posed by non-native species: public vs. conservation managers.

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Rodolphe E Gozlan

Full Text Available Public perception is a key factor influencing current conservation policy. Therefore, it is important to determine the influence of the public, end-users and scientists on the prioritisation of conservation issues and the direct implications for policy makers. Here, we assessed public attitudes and the perception of conservation managers to five non-native species in the UK, with these supplemented by those of an ecosystem user, freshwater anglers. We found that threat perception was not influenced by the volume of scientific research or by the actual threats posed by the specific non-native species. Media interest also reflected public perception and vice versa. Anglers were most concerned with perceived threats to their recreational activities but their concerns did not correspond to the greatest demonstrated ecological threat. The perception of conservation managers was an amalgamation of public and angler opinions but was mismatched to quantified ecological risks of the species. As this suggests that invasive species management in the UK is vulnerable to a knowledge gap, researchers must consider the intrinsic characteristics of their study species to determine whether raising public perception will be effective. The case study of the topmouth gudgeon Pseudorasbora parva reveals that media pressure and political debate has greater capacity to ignite policy changes and impact studies on non-native species than scientific evidence alone.

HERITABILITY AND RESPONSE TO SELECTION FOR GROWTH IN THE F1 GENERATION OF CRAYFISH Procambarus acanthophorus

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Carlos Perez Rostro

2012-11-01

Full Text Available The crayfish Procambarus (A. acanthophorus is a crustacean relevant for regional fisheries in Veracruz, Mexico, with ideal aquaculture characteristics, except for its small size. Thus, a study was conducted with the aim to evaluate the response to selection in the first generation (F1 and heritability (h2 of the crayfish. A group of 2135 organisms with average weight (±S.D. 4.1 ± 1.79 g were captured from the wild (G0, and 10 % (i = 1,755 of the population was selected with the highest body weight by gender: 140 females (5.62 ± 1.97 g and 48 males (6.02 ± 1.9 g, forming the progenitors of the selection line (LS. The control line (LC was formed from a batch obtained at random. Thirty full-sib families were obtained per line (F1, and cultured individually for five months in a recirculation system with mechanical and biological filtration under laboratory conditions and supplied with food twice a day (Camaronina 35 % protein. Monthly heritability (h2 in broad sense was estimated using a full-sib design, based on the components of variance (ANOVA REML method and the growth was compared between lines in the F1. The mean h2's for weight after five months of culture were 0.27±0.11 for LC and 0.34±0.12 for LS, being the LS in F1 9.6 % heavier than the LC, with 84 and 88 % survival at the end of the study. It is possible to implement a breeding program based on selection for species growth.

Feral goats in the Hawaiian Islands: understanding the behavioral ecology of nonnative ungulates with GPS and remote sensing technology

Science.gov (United States)

Mark Chynoweth; Creighton M. Litton; Christopher A. Lepczyk; Susan Cordell

2010-01-01

Nonnative feral ungulates have both direct and indirect impacts on native ecosystems. Hawai`i is particularly susceptible to biological invasions, as the islands have evolved in extreme geographic isolation. In this paper we explore the ecological impacts of nonnative feral goats (Capra hircus) in the Hawaiian Islands, including both the current...

Non-native gobies facilitate the transmission of Bucephalus polymorphus (Trematoda)

Czech Academy of Sciences Publication Activity Database

Ondračková, Markéta; Hudcová, Iveta; Dávidová, Martina; Adámek, Zdeněk; Kašný, M.; Jurajda, Pavel

2015-01-01

Roč. 8, č. 1 (2015), s. 382 ISSN 1756-3305 R&D Projects: GA ČR(CZ) GAP505/12/2569 Institutional support: RVO:68081766 Keywords : Bucephalus polymorphus * Complex life cycle * Goby * Infectivity * Intermediate host * Non-native species * Trematode Subject RIV: EH - Ecology, Behaviour Impact factor: 3.234, year: 2015

A global organism detection and monitoring system for non-native species

Science.gov (United States)

Graham, J.; Newman, G.; Jarnevich, C.; Shory, R.; Stohlgren, T.J.

2007-01-01

Harmful invasive non-native species are a significant threat to native species and ecosystems, and the costs associated with non-native species in the United States is estimated at over $120 Billion/year. While some local or regional databases exist for some taxonomic groups, there are no effective geographic databases designed to detect and monitor all species of non-native plants, animals, and pathogens. We developed a web-based solution called the Global Organism Detection and Monitoring (GODM) system to provide real-time data from a broad spectrum of users on the distribution and abundance of non-native species, including attributes of their habitats for predictive spatial modeling of current and potential distributions. The four major subsystems of GODM provide dynamic links between the organism data, web pages, spatial data, and modeling capabilities. The core survey database tables for recording invasive species survey data are organized into three categories: "Where, Who & When, and What." Organisms are identified with Taxonomic Serial Numbers from the Integrated Taxonomic Information System. To allow users to immediately see a map of their data combined with other user's data, a custom geographic information system (GIS) Internet solution was required. The GIS solution provides an unprecedented level of flexibility in database access, allowing users to display maps of invasive species distributions or abundances based on various criteria including taxonomic classification (i.e., phylum or division, order, class, family, genus, species, subspecies, and variety), a specific project, a range of dates, and a range of attributes (percent cover, age, height, sex, weight). This is a significant paradigm shift from "map servers" to true Internet-based GIS solutions. The remainder of the system was created with a mix of commercial products, open source software, and custom software. Custom GIS libraries were created where required for processing large datasets

Using the Speech Transmission Index for predicting non-native speech intelligibility

NARCIS (Netherlands)

Wijngaarden, S.J. van; Bronkhorst, A.W.; Houtgast, T.; Steeneken, H.J.M.

2004-01-01

While the Speech Transmission Index ~STI! is widely applied for prediction of speech intelligibility in room acoustics and telecommunication engineering, it is unclear how to interpret STI values when non-native talkers or listeners are involved. Based on subjectively measured psychometric functions

Supplementation of Carrot (Daucus carrota as Natural Source of Beta-carotene prepared by Several Methods in Feed to Increase Blue Colour of Freshwater Crayfish Red Claw (Cherax quadricarinatus

Directory of Open Access Journals (Sweden)

Woro H. Satyantini

2012-02-01

Full Text Available Red claw (Cherax quadricarinatus is one kind of freshwater crayfish that can cultured as consumption or ornamental fish commodities.  The colour of body was important character for performance of red claw as ornamental fish commodity.  Red claw with blue body colour is more expensive than brown.  The purpose of  this experiment was to know the influence addition of carrot with several methods in feed on blue colour  of freshwater crayfish red claw and which was the best preparation method to increase blue colour of freshwater crayfish red claw. The experiment used Completely Randomized Design with four treatments: A (control, B (extract, C (juice and D (shreeded of carrot with 45 ppm dose and five time replicates.  Data was analysed with Kruskal-Wallis and continued with Z test. Result of the experiment was showed that addition of carrot as natural source of beta-carotene with several preparation in feed increase significantly (P Keywords: freshwater crayfish, colour of red claw, carrot, beta-carotene   ABSTRAK Red claw (Cherax quadricarinatus adalah salah satu jenis lobster air tawar yang dapat dibudidayakan sebagai komoditas konsumsi maupun hias.  Sebagai komoditas ikan hias, warna tubuh merupakan karakter penting untuk menunjang penampilan red claw.  Red claw ukuran konsumsi yang memiliki warna biru akan memiliki nilai jual yang lebih tinggi daripada red claw berwarna coklat.  Tujuan penelitian ini untuk mengetahui pengaruh penambahan wortel sebagai sumber beta karoten alami dengan beberapa metoda pengolahan pada pakan terhadap peningkatan warna biru lobster red claw. Penelitian menggunakan Rancangan Acak Lengkap dengan 4 perlakuan : A (kontrol, B (ekstrak, C (jus dan D (serutan wortel dengan menggunakan dosis 45 ppm beta karoten dan ulangan 5 kali.  Data dianalisis dengan uji Kruskal-Wallis dan dilanjutkan dengan uji Z.  Hasil penelitian menunjukkan bahwa penambahan wortel sebagai sumber beta karoten alami dengan beberapa metode

Fleshy fruit removal and nutritional composition of winter-fruiting plants: a comparison of non-native invasive and native species

Science.gov (United States)

Cathryn H. Greenberg; Scott T. Walter

2010-01-01

Invasive, non-native plants threaten forest ecosystems by reducing native plant species richness and potentially altering ecosystem processes. Seed dispersal is critical for successful invasion and range expansion by non-native plants; dispersal is likely to be enhanced if they can successfully compete with native plants for disperser services. Fruit production by non-...

Acoustic-Phonetic Versus Lexical Processing in Nonnative Listeners Differing in Their Dominant Language.

Science.gov (United States)

Shi, Lu-Feng; Koenig, Laura L

2016-09-01

Nonnative listeners have difficulty recognizing English words due to underdeveloped acoustic-phonetic and/or lexical skills. The present study used Boothroyd and Nittrouer's (1988)j factor to tease apart these two components of word recognition. Participants included 15 native English and 29 native Russian listeners. Fourteen and 15 of the Russian listeners reported English (ED) and Russian (RD) to be their dominant language, respectively. Listeners were presented 119 consonant-vowel-consonant real and nonsense words in speech-spectrum noise at +6 dB SNR. Responses were scored for word and phoneme recognition, the logarithmic quotient of which yielded j. Word and phoneme recognition was comparable between native and ED listeners but poorer in RD listeners. Analysis of j indicated less effective use of lexical information in RD than in native and ED listeners. Lexical processing was strongly correlated with the length of residence in the United States. Language background is important for nonnative word recognition. Lexical skills can be regarded as nativelike in ED nonnative listeners. Compromised word recognition in ED listeners is unlikely a result of poor lexical processing. Performance should be interpreted with caution for listeners dominant in their first language, whose word recognition is affected by both lexical and acoustic-phonetic factors.

Are native songbird populations affected by non-native plant invasion?

Science.gov (United States)

Amanda M. Conover; Christopher K. Williams; Vincent. D' Amico

2011-01-01

Development into forested areas is occurring rapidly across the United States, and many of the remnant forests within suburban landscapes are being fragmented into smaller patches, impacting the quality of this habitat for avian species. An ecological effect linked to forest fragmentation is the invasion of non-native plants into the ecosystem.

 Invasibility of three major non-native invasive shrubs and associated factors in Upper Midwest U.S. forest lands

Science.gov (United States)

W. Keith Moser; Zhaofei Fan; Mark H. Hansen; Michael K. Crosby; Shirley X. Fan

2016-01-01

We used non-native invasive plant data from the US Forest Service’s Forest Inventory and Analysis (FIA) program, spatial statistical methods, and the space (cover class)-for-time approach to quantify the invasion potential and success ("invasibility") of three major invasive shrubs (multiflora rose, non-native bush honeysuckles, and common buckthorn...

Visual and auditory digit-span performance in native and nonnative speakers

NARCIS (Netherlands)

Olsthoorn, N.M.; Andringa, S.; Hulstijn, J.H.

2014-01-01

We compared 121 native and 114 non-native speakers of Dutch (with 35 different first languages) on four digit-span tasks, varying modality (visual/auditory) and direction (forward/backward). An interaction was observed between nativeness and modality, such that, while natives performed better than

Calcium transport mechanism in molting crayfish revealed by microanalysis

International Nuclear Information System (INIS)

Mizuhira, V.; Ueno, M.

1983-01-01

Crayfish provide a good model in which to study the transport mechanism of Ca ions. During the molting stage, decalcified Ca ions are transferred into the blood and accumulate in the gastrolith epithelium, after which a gastrolith is formed on the surface of the epithelium. The gastrolith is dissolved in the stomach after molting, and the Ca is reabsorbed and redistributed throughout the newly formed exoskeleton. We studied the mechanism of Ca transport by cytochemical precipitation of Ca ions and by electron microanalysis, including X-ray microanalysis (EDX) and electron energy-loss spectroscopy (EELS), with a computer. In EDX analysis, the fine precipitates of K-antimonate in the gastrolith mitochondria clearly defined Ca with antimony; we also observed a large amount of Ca-oxalate in the mitochondria, and Ca-K X-ray pulses were clearly defined. Ca-K X-rays were also detected from fresh freeze-substituted mitochondria. Finally, we succeeded in taking a Ca-L EELS image from the mitochondria of fresh freeze-substituted thin sections. Only a very small amount of Ca was detected from the cell membrane and other organelles. Ca-adenosine triphosphatase (ATPase) and Mg-ATPase activity was also very clearly demonstrated in the mitochondria. These enzymes may play an important role in Ca metabolism

Isolation of crustecdysone (20R-hydroxyecdysone) from a crayfish (Jasus lalandei H. Milne-Edwards)

Science.gov (United States)

Horn, D. H. S.; Fabbri, S.; Hampshire, F.; Lowe, M. E.

1968-01-01

1. A small amount (2mg.) of crustecdysone, a moulting hormone of crustaceans, was isolated from 1 ton of crayfish waste. 2. The purification procedure used was developed with the aid of crustacean and insect bioassays. 3. CM-Sephadex was found to be superior to Sephadex and very effective for the chromatographic separation of crustecdysone from other non-ionic compounds. The higher efficiency of CM-Sephadex is attributed to the greater number of carboxyl groups available for hydrogen-bonding. 4. Reversed-phase chromatography, with butan-1-ol–cyclohexane mixtures as the stationary phase and water as the flowing phase, proved superior to countercurrent distribution with these solvents for the fractionation of purified extracts. 5. A second moulting hormone, deoxycrustecdysone, and the red-concentrating hormone were obtained in a partially purified form. PMID:5685865

Field and laboratory tests on acute toxicity of cadmium to freshwater crayfish

Energy Technology Data Exchange (ETDEWEB)

1986-09-01

Environmental regulatory standards for cadmium (EPA 1980), like those for most pollutants, are based on acute, laboratory toxicity tests of single species. Such tests can be conducted rapidly and inexpensively in comparison to acute or chronic field studies, but their validity has often been questioned. Laboratory-based criteria are subject to two criticisms: (1) chemical and physical conditions differ greatly in degree and variability from laboratory to field, and (2) species are not isolated, but live in an ecosystem of interacting taxa and biofeedback. To investigate the validity of basing field toxicity standards on laboratory data, the authors subjected the freshwater crayfish Orconectes immunis for 96 h to various levels of cadmium in laboratory aquaria and experimental ponds. The study was designed to evaluate in part the first criticism of lab-based criteria. The studies were conducted concurrently with similar short-term experiments on the fathead minnow, Pimephales promelas, and coincided with studies of chronic cadmium stress on fathead minnows in experimental ponds.

Toxic Exposure Surveillance System (TESS)-based characterization of U.S. non-native venomous snake exposures, 1995-2004.

Science.gov (United States)

Seifert, Steven A; Oakes, Jennifer A; Boyer, Leslie V

2007-01-01

Non-native (exotic) snake exposures in the United States have not been systematically characterized. The Toxic Exposure Surveillance System (TESS) database of the American Association of Poison Control Centers was analyzed to quantify the number and types, demographic associations, clinical presentations, managements and outcomes, and the health resource utilization of non-native snake exposures. From 1995 through 2004, there were 399 non-native exposures in the TESS database. Of these, 350 snakes (87%) were identified by genus and species, comprising at least 77 different varieties. Roughly equal percentages of snakes originated in Asia, Africa and Latin America, with a smaller number from the Middle-East, Australia, and Europe. Nearly half were viperids and a little more than a third were elapids. The vast majority of exposed individuals were adults. However, almost 15% were aged 17 years or less, and almost 7% were children aged 5 years or younger. Eighty-four percent were males. The vast majority of exposures occurred at the victim's own residence. Over 50% were evaluated at a healthcare facility, with 28.7% admitted to an ICU. Overall, 26% of patients were coded as receiving antivenom treatment. Coded outcomes were similar between viperid and elapid envenomations. There were three deaths, two involving viperid snakes and one elapid. Enhancements to the TESS database are required for better precision in and more complete characterization of non-native snake envenomations.

Recreational freshwater fishing drives non-native aquatic species richness patterns at a continental scale

Data.gov (United States)

U.S. Environmental Protection Agency — Aim. Mapping the geographic distribution of non-native aquatic species is a critically important precursor to understanding the anthropogenic and environmental...

Fitness benefits of the fruit fly Rhagoletis alternata on a non-native rose host.

Science.gov (United States)

Meijer, Kim; Smit, Christian; Schilthuizen, Menno; Beukeboom, Leo W

2016-05-01

Many species have been introduced worldwide into areas outside their natural range. Often these non-native species are introduced without their natural enemies, which sometimes leads to uncontrolled population growth. It is rarely reported that an introduced species provides a new resource for a native species. The rose hips of the Japanese rose, Rosa rugosa, which has been introduced in large parts of Europe, are infested by the native monophagous tephritid fruit fly Rhagoletis alternata. We studied differences in fitness benefits between R. alternata larvae using R. rugosa as well as native Rosa species in the Netherlands. R. alternata pupae were larger and heavier when the larvae fed on rose hips of R. rugosa. Larvae feeding on R. rugosa were parasitized less frequently by parasitic wasps than were larvae feeding on native roses. The differences in parasitization are probably due to morphological differences between the native and non-native rose hips: the hypanthium of a R. rugosa hip is thicker and provides the larvae with the possibility to feed deeper into the hip, meaning that the parasitoids cannot reach them with their ovipositor and the larvae escape parasitization. Our study shows that native species switching to a novel non-native host can experience fitness benefits compared to the original native host.

Cognitive Processes Underlying Nonnative Speech Production: The Significance of Recurrent Sequences.

Science.gov (United States)

Oppenheim, Nancy

This study was designed to identify whether advanced nonnative speakers of English rely on recurrent sequences to produce fluent speech in conformance with neural network theories and symbolic network theories; participants were 6 advanced, speaking and listening university students, aged 18-37 years (their native countries being Korea, Japan,…

Ethical Considerations in Conducting Research with Non-Native Speakers of English

Science.gov (United States)

Koulouriotis, Joanna

2011-01-01

The ethical considerations of three education researchers working with non-native English-speaking participants were examined from a critical theory stand-point in the light of the literature on research ethics in various disciplines. Qualitative inquiry and data analysis were used to identify key themes, which centered around honor and respect…

Invasion by non-native brook trout in Panther Creek, Idaho: Roles of habitat quality, biotic resistance, and connectivity to source habitats

Science.gov (United States)

Joseph R. Benjamin; Jason B. Dunham; Matthew R. Dare

2007-01-01

Theoretical models and empirical evidence suggest that the invasion of nonnative species in freshwaters is facilitated through the interaction of three factors: habitat quality, biotic resistance, and connectivity. We measured variables that represented each factor to determine which were associated with the occurrence of nonnative brook trout Salvelinus...

Distribution and status of five non-native fish species in the Tampa Bay drainage (USA), a hot spot for fish introductions

Science.gov (United States)

Lawson, Katelyn M.; Tuckett, Quenton M.; Ritch, Jared L.; Nico, Leo; Fuller, Pam; Matheson, Richard E.; Hill, Jeffrey E.

2017-01-01

The Tampa Bay region of Florida (USA) is a hot spot for non-native freshwater fishes. However, published information on most non-native fishes in the basin is not current. Systematic sampling efforts targeting non-native fishes in the region were conducted from 2013–2015 by the University of Florida Tropical Aquaculture Laboratory. Data from these recent surveys were analyzed, along with historic and new data from published and unpublished sources, to assess current fish distributions and determine status. We focus on five of the non-native species sampled: pike killifish Belonesox belizanus Kner, 1860, green swordtail Xiphophorus hellerii Heckel, 1848, southern platyfish Xiphophorus maculatus (Günther, 1866), Mayan cichlid Mayaheros urophthalmus (Günther, 1862), and Jack Dempsey Rocio octofasciata (Regan, 1903). All five were found to have reproducing populations in the basin, each showing broader distributions than previously indicated. Non-native populations of four of the species have persisted in the Tampa Bay region since at least the 1990s. In contrast, the presence of Mayan cichlid in the basin was not confirmed until 2004. Based on numbers, distributions, and years of persistence, these five species all maintain established populations. Pike killifish and Mayan cichlid are established and spreading throughout multiple habitat types, while green swordtail, southern platyfish, and Jack Dempsey are localized and found primarily in more marginal habitats (e.g., small ditches and first order tributary streams). Factors affecting continued existence and distributions likely include aquaculture, biotic resistance, and thermal and salinity tolerances. We also clarify non-native species status determination using a multi-agency collaborative approach, and reconcile differences in terminology usage and interpretation.

Changes in the fish fauna of the Kissimmee River basin, peninsular Florida: Nonnative additions

Science.gov (United States)

Nico, L.G.

2005-01-01

Recent decades have seen substantial changes in fish assemblages in rivers of peninsular Florida. The most striking change has involved the addition of nonnative fishes, including taxa from Asia, Africa, and Central and South America. I review recent and historical records of fishes occurring in the Kissimmee River basin (7,800 km2), a low-gradient drainage with 47 extant native fishes (one possibly the result of an early transplant), at least 7 foreign fishes (most of which are widely established), and a stocked hybrid. Kissimmee assemblages include fewer marine fishes than the nearby Peace and Caloosahatchee rivers, and fewer introduced foreign fishes than south Florida canals. Fish assemblages of the Kissimmee and other subtropical Florida rivers are dynamic, due to new introductions, range expansions of nonnative fishes already present, and periodic declines in nonnative fish populations during occasional harsh winters. The addition, dispersal, and abundance of nonnative fishes in the basin is linked to many factors, including habitat disturbance, a subtropical climate, and the fact that the basin is centrally located in a region where drainage boundaries are blurred and introductions of foreign fishes commonplace. The first appearance of foreign fishes in the basin coincided with the complete channelization of the Kissimmee River in the 1970s. Although not a causal factor, artificial waterways connecting the upper lakes and channelization of the Kissimmee River have facilitated dispersal. With one possible exception, there have been no basin-wide losses of native fishes. When assessing change in peninsular Florida waters, extinction or extirpation of fishes appears to be a poor measure of impact. No endemic species are known from peninsular Florida (although some endemic subspecies have been noted). Most native freshwater fishes are themselves descended from recent invaders that reached the peninsula from the main continent. These invasions likely were

Economic impacts of non-native forest insects in the continental United States.

Directory of Open Access Journals (Sweden)

Juliann E Aukema

Full Text Available Reliable estimates of the impacts and costs of biological invasions are critical to developing credible management, trade and regulatory policies. Worldwide, forests and urban trees provide important ecosystem services as well as economic and social benefits, but are threatened by non-native insects. More than 450 non-native forest insects are established in the United States but estimates of broad-scale economic impacts associated with these species are largely unavailable. We developed a novel modeling approach that maximizes the use of available data, accounts for multiple sources of uncertainty, and provides cost estimates for three major feeding guilds of non-native forest insects. For each guild, we calculated the economic damages for five cost categories and we estimated the probability of future introductions of damaging pests. We found that costs are largely borne by homeowners and municipal governments. Wood- and phloem-boring insects are anticipated to cause the largest economic impacts by annually inducing nearly $1.7 billion in local government expenditures and approximately $830 million in lost residential property values. Given observations of new species, there is a 32% chance that another highly destructive borer species will invade the U.S. in the next 10 years. Our damage estimates provide a crucial but previously missing component of cost-benefit analyses to evaluate policies and management options intended to reduce species introductions. The modeling approach we developed is highly flexible and could be similarly employed to estimate damages in other countries or natural resource sectors.

An assessment of a proposal to eradicate non-native fish from ...

African Journals Online (AJOL)

African Journal of Aquatic Science ... A pilot project to evaluate the use of the piscicide rotenone to eradicate non-native fish from selected reaches in four rivers has been proposed by CapeNature, the conservation ... It is expected that the project will be successful while having minimal impact on other aquatic fauna.

Non-Native English Speakers and Nonstandard English: An In-Depth Investigation

Science.gov (United States)

Polat, Brittany

2012-01-01

Given the rising prominence of nonstandard varieties of English around the world (Jenkins 2007), learners of English as a second language are increasingly called on to communicate with speakers of both native and non-native nonstandard English varieties. In many classrooms around the world, however, learners continue to be exposed only to…

Nonnative English-Speaking Teachers in the United States: Issues of Identity

Science.gov (United States)

Diniz de Figueiredo, Eduardo Henrique

2011-01-01

The present study investigated how nonnative English-speaking teachers (NNESTs) working in K-12 schools in the United States perceive their identities in relation to the school environment and its norms, their coworkers and administrators and the students and their families. Specific attention was given to the teachers' concerns prior to arrival…

COMPARISON OF ANNUAL PRODUCTION ECOLOGY OF NATIVE EELGRASS ZOSTERA MARINA AND THE NON-NATIVE DWARF EELGRASS Z. JAPONICA IN YAQUINA BAY, OREGON

Science.gov (United States)

When non-native plant species invade a system they often change patterns of primary production. I evaluate the contribution of the seagrass Zostera marina and it's non-native congener Z. japonica to primary production in Yaquina Bay. Few measurements of Z. japonica production e...

Effects of both ecdysone and the acclimation to low temperature, on growth and metabolic rate of juvenile freshwater crayfish Cherax quadricarinatus (Decapoda, Parastacidae

Directory of Open Access Journals (Sweden)

Anouk Chaulet

2013-06-01

Full Text Available Growth, metabolic rate, and energy reserves of Cherax quadricarinatus (von Martens, 1868 juveniles were evaluated in crayfish acclimated for 16 weeks to either 25ºC (temperature near optimum or 20ºC (marginal for the species. Additionally, the modulating effect of ecdsyone on acclimation was studied. After 12 weeks of exposure, weight gain of both experimental groups acclimated to 25ºC (control: C25, and ecdysone treated: E25 was significantly higher than that of those groups acclimated to 20ºC (C20 and E20. A total compensation in metabolic rate was seen after acclimation from 25ºC to 20ºC; for both the control group and the group treated with ecdysone. A Q10value significantly higher was only observed in the group acclimated to 20ºC and treated with ecdysone. A reduction of glycogen reserves in both hepatopancreas and muscle, as well as a lower protein content in muscle, was seen in both groups acclimated to 20ºC. Correspondingly, glycemia was always higher in these groups. Increased lipid levels were seen in the hepatopancreas of animals acclimated to 20ºC, while a higher lipid level was also observed in muscle at 20ºC, but only in ecdysone-treated crayfish.

Astaxanthin from Crayfish (Procambarus clarkii as a Pigmentary Ingredient in the Feed of Laying Hens

Directory of Open Access Journals (Sweden)

Garrido-Fernández, J.

2008-06-01

Full Text Available Chicken egg yolks generally owe their color to yellow carotenoids. The addition of synthetic red pigments allows changes in color, from the original yellow to red hues which may be more appealing to consumers in certain markets.Our aim has been to test whether ground crayfish shells, which are a rich and natural source of astaxanthin, produce detectable changes in the coloration of egg yolks through the accumulation of this carotenoid. Laying hens were fed with a commercial feed mixed with crayfish powder and the carotenoid profiles of the yolks in the eggs laid during the trial were monitored by HPLC. The analyses showed a progressive increase in the astaxanthin concentration in the egg yolks, reaching similar levels to those obtained for the rest of present carotenoid pigments.La yema de huevo de gallina debe su coloración a la presencia de carotenoides de tonalidad amarilla. La adición de colorantes sintéticos de tonalidades rojas permite modificar e incrementar la coloración de la yema desde el amarillo original a tonos rojos que pueden ser demandados en ciertos mercados según las preferencias del consumidor. El objetivo del trabajo fue probar si un triturado obtenido a partir de caparazones de cangrejo, que es una fuente natural y rica en astaxanteno, produce cambios detectables en la coloración de la yema de huevo por la acumulación de dicho carotenoide. Las gallinas ponedoras se alimentaron con un pienso comercial al que se adicionó triturado de caparazón de cangrejo. Se realizó un seguimiento de los cambios en la composición carotenoide (mediante HPLC de la yema de los huevos puestos durante el periodo de alimentación suplementada. Los análisis mostraron una progresiva incorporación de astaxanteno que alcanzó niveles similares al resto de carotenoides presentes inicialmente en la yema.

Microscopic examination of skin in native and nonnative fish from Lake Tahoe exposed to ultraviolet radiation and fluoranthene

Energy Technology Data Exchange (ETDEWEB)

Gevertz, Amanda K., E-mail: agevertz@geiconsultants.com [Miami University, Department of Zoology, 212 Pearson Hall, Oxford 45056, Ohio (United States); GEI Consultants, Inc. , 4601 DTC Blvd, Suite 900, Denver 80237, Colorado (United States); Oris, James T., E-mail: orisjt@miamioh.edu [Miami University, Department of Zoology, 212 Pearson Hall, Oxford 45056, Ohio (United States)

2014-02-15

Highlights: •PAH cause photo-induced toxicity in aquatic organisms in the natural environment. •Montane lakes like Lake Tahoe receive PAH exposure from recreational watercraft. •These lakes are susceptible to invasion and establishment of non-native species. •Non-natives were less tolerant to photo-toxicity compared to native species. •Sensitivity differences were related to levels of oxidative damage in epidermis. -- Abstract: The presence of nonnative species in Lake Tahoe (CA/NV), USA has been an ongoing concern for many decades, and the management of these species calls for an understanding of their ability to cope with the Lake's stressors and for an understanding of their potential to out-compete and reduce the populations of native species. Decreasing levels of ultraviolet radiation (UVR) due to eutrophication and increasing levels of phototoxic polycyclic aromatic hydrocarbons (PAHs) due to recreational activities may combine to affect the relative ability of native versus nonnative fish species to survive in the lake. Following a series of toxicity tests which exposed larvae of the native Lahontan redside minnow (Richardsonius egregius) and the nonnative warm-water bluegill sunfish (Lepomis macrochirus) to UVR and FLU, the occurrence of skin damage and/or physiologic defense mechanisms were studied using multiple microscopic techniques. The native minnow appeared to exhibit fewer instances of skin damage and increased instances of cellular coping mechanisms. This study supports the results of previous work conducted by the authors, who determined that the native redside minnow is the more tolerant of the two species, and that setting and adhering to a water quality standard for UVR transparency may aid in preventing the spread of the less tolerant nonnative bluegill and similar warm-water species.

Functional diversity measures revealed impacts of non-native species and habitat degradation on species-poor freshwater fish assemblages.

Science.gov (United States)

Colin, Nicole; Villéger, Sébastien; Wilkes, Martin; de Sostoa, Adolfo; Maceda-Veiga, Alberto

2018-06-01

Trait-based ecology has been developed for decades to infer ecosystem responses to stressors based on the functional structure of communities, yet its value in species-poor systems is largely unknown. Here, we used an extensive dataset in a Spanish region highly prone to non-native fish invasions (15 catchments, N=389 sites) to assess for the first time how species-poor communities respond to large-scale environmental gradients using a taxonomic and functional trait-based approach in riverine fish. We examined total species richness and three functional trait-based indices available when many sites have ≤3 species (specialization, FSpe; originality, FOri and entropy, FEnt). We assessed the responses of these taxonomic and functional indices along gradients of altitude, water pollution, physical habitat degradation and non-native fish biomass. Whilst species richness was relatively sensitive to spatial effects, functional diversity indices were responsive across natural and anthropogenic gradients. All four diversity measures declined with altitude but this decline was modulated by physical habitat degradation (richness, FSpe and FEnt) and the non-native:total fish biomass ratio (FSpe and FOri) in ways that varied between indices. Furthermore, FSpe and FOri were significantly correlated with Total Nitrogen. Non-native fish were a major component of the taxonomic and functional structure of fish communities, raising concerns about potential misdiagnosis between invaded and environmentally-degraded river reaches. Such misdiagnosis was evident in a regional fish index widely used in official monitoring programs. We recommend the application of FSpe and FOri to extensive datasets from monitoring programs in order to generate valuable cross-system information about the impacts of non-native species and habitat degradation, even in species-poor systems. Scoring non-native species apart from habitat degradation in the indices used to determine ecosystem health is

Non-native (exotic) snake envenomations in the U.S., 2005-2011.

Science.gov (United States)

Warrick, Brandon J; Boyer, Leslie V; Seifert, Steven A

2014-09-29

Non-native (exotic) snakes are a problematic source of envenomation worldwide. This manuscript describes the current demographics, outcomes and challenges of non-native snakebites in the United States (U.S.). We performed a retrospective case series of the National Poison Data System (NPDS) database between 2005 and 2011. There were 258 human exposures involving at least 61 unique exotic venomous species (average = 37 per year; range = 33-40). Males comprised 79% and females 21%. The average age was 33 years with 16% less than 20 years old. 70% of bites occurred in a private residence and 86% were treated at a healthcare facility. 35% of cases received antivenom and 10% were given antibiotics. This study is compared to our previous study (1994-2004) in which there was a substantial coding error rate. Software modifications significantly reduced coding errors. Identification and acquisition of appropriate antivenoms pose a number of logistical difficulties in the management of these envenomations. In the U.S., poison centers have valuable systems and clinical roles in the provision of expert consultation and in the management of these cases.

Determining effective riparian buffer width for nonnative plant exclusion and habitat enhancement

Science.gov (United States)

Gavin Ferris; Vincent D' Amico; Christopher K. Williams

2012-01-01

Nonnative plants threaten native biodiversity in landscapes where habitats are fragmented. Unfortunately, in developed areas, much of the remaining forested habitat occurs in fragmented riparian corridors. Because forested corridors of sufficient width may allow forest interior specializing native species to retain competitive advantage over edge specialist and...

Thermal physiology of native cool-climate, and non-native warm-climate Pumpkinseed sunfish raised in a common environment.

Science.gov (United States)

Rooke, Anna C; Burness, Gary; Fox, Michael G

2017-02-01

Contemporary evolution of thermal physiology has the potential to help limit the physiological stress associated with rapidly changing thermal environments; however it is unclear if wild populations can respond quickly enough for such changes to be effective. We used native Canadian Pumpkinseed (Lepomis gibbosus) sunfish, and non-native Pumpkinseed introduced into the milder climate of Spain ~100 years ago, to assess genetic differences in thermal physiology in response to the warmer non-native climate. We compared temperature performance reaction norms of two Canadian and two Spanish Pumpkinseed populations born and raised within a common environment. We found that Canadian Pumpkinseed had higher routine metabolic rates when measured at seasonally high temperatures (15°C in winter, 30°C in summer), and that Spanish Pumpkinseed had higher critical thermal maxima when acclimated to 30°C in the summer. Growth rates were not significantly different among populations, however Canadian Pumpkinseed tended to have faster growth at the warmest temperatures measured (32°C). The observed differences in physiology among Canadian and Spanish populations at the warmest acclimation temperatures are consistent with the introduced populations being better suited to the warmer non-native climate than native populations. The observed differences could be the result of either founder effects, genetic drift, and/or contemporary adaptive evolution in the warmer non-native climate. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaluating ecosystem services provided by non-native species: an experimental test in California grasslands.

Science.gov (United States)

Stein, Claudia; Hallett, Lauren M; Harpole, W Stanley; Suding, Katharine N

2014-01-01

The concept of ecosystem services--the benefits that nature provides to human's society--has gained increasing attention over the past decade. Increasing global abiotic and biotic change, including species invasions, is threatening the secure delivery of these ecosystem services. Efficient evaluation methods of ecosystem services are urgently needed to improve our ability to determine management strategies and restoration goals in face of these new emerging ecosystems. Considering a range of multiple ecosystem functions may be a useful way to determine such strategies. We tested this framework experimentally in California grasslands, where large shifts in species composition have occurred since the late 1700's. We compared a suite of ecosystem functions within one historic native and two non-native species assemblages under different grazing intensities to address how different species assemblages vary in provisioning, regulatory and supporting ecosystem services. Forage production was reduced in one non-native assemblage (medusahead). Cultural ecosystem services, such as native species diversity, were inherently lower in both non-native assemblages, whereas most other services were maintained across grazing intensities. All systems provided similar ecosystem services under the highest grazing intensity treatment, which simulated unsustainable grazing intensity. We suggest that applying a more comprehensive ecosystem framework that considers multiple ecosystem services to evaluate new emerging ecosystems is a valuable tool to determine management goals and how to intervene in a changing ecosystem.

Teaching a Growing a Population of Non-Native English-Speaking Students in American Universities: Cultural and Linguistic Challenges

OpenAIRE

Maria Cristina Fava

2016-01-01

The increasing number of non-native English speaking students in American universities, mostly from Asian countries, presents unprecedented challenges and calls for an in-depth study on how we teach western art music history. This essay challenges some aspects of liberal multiculturalism and proposes the creation of channels of communication that allow non-native English speaking students to understand the premises of a Eurocentric system of knowledge without undermining their own cultural ba...

The intercultural identities of nonnative English teachers : An overview of research worldwide

NARCIS (Netherlands)

Chen, D.; Tigelaar, E.H.; Verloop, N.

2016-01-01

Nonnative-English-speaking teachers who teach English as a second or foreign language (ESL/EFL) can play an important role in the promotion of intercultural competence and often have an advantage over native-English-speaking ESL/EFL teachers because they once were language learners and more aware of

Evolution under changing climates: climatic niche stasis despite rapid evolution in a non-native plant.

Science.gov (United States)

Alexander, Jake M

2013-09-22

A topic of great current interest is the capacity of populations to adapt genetically to rapidly changing climates, for example by evolving the timing of life-history events, but this is challenging to address experimentally. I use a plant invasion as a model system to tackle this question by combining molecular markers, a common garden experiment and climatic niche modelling. This approach reveals that non-native Lactuca serriola originates primarily from Europe, a climatic subset of its native range, with low rates of admixture from Asia. It has rapidly refilled its climatic niche in the new range, associated with the evolution of flowering phenology to produce clines along climate gradients that mirror those across the native range. Consequently, some non-native plants have evolved development times and grow under climates more extreme than those found in Europe, but not among populations from the native range as a whole. This suggests that many plant populations can adapt rapidly to changed climatic conditions that are already within the climatic niche space occupied by the species elsewhere in its range, but that evolution to conditions outside of this range is more difficult. These findings can also help to explain the prevalence of niche conservatism among non-native species.

Invasion of non-native grasses causes a drop in soil carbon storage in California grasslands

Energy Technology Data Exchange (ETDEWEB)

Koteen, Laura E; Harte, John [Energy and Resources Group, 310 Barrows Hall, University of California, Berkeley, CA 94720 (United States); Baldocchi, Dennis D, E-mail: lkoteen@berkeley.edu [Department of Environmental Science, Policy and Management, 137 Mulford Hall, University of California, Berkeley, CA 94720 (United States)

2011-10-15

Vegetation change can affect the magnitude and direction of global climate change via its effect on carbon cycling among plants, the soil and the atmosphere. The invasion of non-native plants is a major cause of land cover change, of biodiversity loss, and of other changes in ecosystem structure and function. In California, annual grasses from Mediterranean Europe have nearly displaced native perennial grasses across the coastal hillsides and terraces of the state. Our study examines the impact of this invasion on carbon cycling and storage at two sites in northern coastal California. The results suggest that annual grass invasion has caused an average drop in soil carbon storage of 40 Mg/ha in the top half meter of soil, although additional mechanisms may also contribute to soil carbon losses. We attribute the reduction in soil carbon storage to low rates of net primary production in non-native annuals relative to perennial grasses, a shift in rooting depth and water use to primarily shallow sources, and soil respiratory losses in non-native grass soils that exceed production rates. These results indicate that even seemingly subtle land cover changes can significantly impact ecosystem functions in general, and carbon storage in particular.

Invasion of non-native grasses causes a drop in soil carbon storage in California grasslands

International Nuclear Information System (INIS)

Koteen, Laura E; Harte, John; Baldocchi, Dennis D

2011-01-01

Vegetation change can affect the magnitude and direction of global climate change via its effect on carbon cycling among plants, the soil and the atmosphere. The invasion of non-native plants is a major cause of land cover change, of biodiversity loss, and of other changes in ecosystem structure and function. In California, annual grasses from Mediterranean Europe have nearly displaced native perennial grasses across the coastal hillsides and terraces of the state. Our study examines the impact of this invasion on carbon cycling and storage at two sites in northern coastal California. The results suggest that annual grass invasion has caused an average drop in soil carbon storage of 40 Mg/ha in the top half meter of soil, although additional mechanisms may also contribute to soil carbon losses. We attribute the reduction in soil carbon storage to low rates of net primary production in non-native annuals relative to perennial grasses, a shift in rooting depth and water use to primarily shallow sources, and soil respiratory losses in non-native grass soils that exceed production rates. These results indicate that even seemingly subtle land cover changes can significantly impact ecosystem functions in general, and carbon storage in particular.

Invasion of non-native grasses causes a drop in soil carbon storage in California grasslands

Science.gov (United States)

Koteen, Laura E.; Baldocchi, Dennis D.; Harte, John

2011-10-01

Vegetation change can affect the magnitude and direction of global climate change via its effect on carbon cycling among plants, the soil and the atmosphere. The invasion of non-native plants is a major cause of land cover change, of biodiversity loss, and of other changes in ecosystem structure and function. In California, annual grasses from Mediterranean Europe have nearly displaced native perennial grasses across the coastal hillsides and terraces of the state. Our study examines the impact of this invasion on carbon cycling and storage at two sites in northern coastal California. The results suggest that annual grass invasion has caused an average drop in soil carbon storage of 40 Mg/ha in the top half meter of soil, although additional mechanisms may also contribute to soil carbon losses. We attribute the reduction in soil carbon storage to low rates of net primary production in non-native annuals relative to perennial grasses, a shift in rooting depth and water use to primarily shallow sources, and soil respiratory losses in non-native grass soils that exceed production rates. These results indicate that even seemingly subtle land cover changes can significantly impact ecosystem functions in general, and carbon storage in particular.

Genetically based differentiation in growth of multiple non-native plant species along a steep environmental gradient.

Science.gov (United States)

Haider, Sylvia; Kueffer, Christoph; Edwards, Peter J; Alexander, Jake M

2012-09-01

A non-native plant species spreading along an environmental gradient may need to adjust its growth to the prevailing conditions that it encounters by a combination of phenotypic plasticity and genetic adaptation. There have been several studies of how non-native species respond to changing environmental conditions along latitudinal gradients, but much less is known about elevational gradients. We conducted a climate chamber experiment to investigate plastic and genetically based growth responses of 13 herbaceous non-native plants along an elevational gradient from 100 to 2,000 m a.s.l. in Tenerife. Conditions in the field ranged from high anthropogenic disturbance but generally favourable temperatures for plant growth in the lower half of the gradient, to low disturbance but much cooler conditions in the upper half. We collected seed from low, mid and high elevations and grew them in climate chambers under the characteristic temperatures at these three elevations. Growth of all species was reduced under lower temperatures along both halves of the gradient. We found consistent genetically based differences in growth over the upper elevational gradient, with plants from high-elevation sites growing more slowly than those from mid-elevation ones, while the pattern in the lower part of the gradient was more mixed. Our data suggest that many non-native plants might respond to climate along elevational gradients by genetically based changes in key traits, especially at higher elevations where low temperatures probably impose a stronger selection pressure. At lower elevations, where anthropogenic influences are greater, higher gene flow and frequent disturbance might favour genotypes with broad ecological amplitudes. Thus the importance of evolutionary processes for invasion success is likely to be context-dependent.

The role of wildfire in the establishment and range expansion of nonnative plant species into natural areas: A review of current literature

Science.gov (United States)

Mara Johnson; Lisa J. Rew; Bruce D. Maxwell; Steve Sutherland

2006-01-01

Nonnative invasive plants are one of the greatest threats to natural ecosystems worldwide (Vitousek et al. 1996). In fact, their spread has been described as "a raging biological wildfire" (Dewey et al. 1995). Disturbances tend to create conditions that are favorable for germination and establishment of plant species. Nonnative plant species are often...

From Blood to Brain: Adult-Born Neurons in the Crayfish Brain Are the Progeny of Cells Generated by the Immune System

Directory of Open Access Journals (Sweden)

Barbara S. Beltz

2017-12-01

Full Text Available New neurons continue to be born and integrated into the brains of adult decapod crustaceans. Evidence in crayfish indicates that the 1st-generation neural precursors that generate these adult-born neurons originate in the immune system and travel to the neurogenic niche via the circulatory system. These precursors are attracted to the niche, become integrated amongst niche cells, and undergo mitosis within a few days; both daughters of this division migrate away from the niche toward the brain clusters where they will divide again and differentiate into neurons. In the crustacean brain, the rate of neuronal production is highly sensitive to serotonin (5-hydroxytryptamine, 5-HT levels. These effects are lineage-dependent, as serotonin's influence is limited to late 2nd-generation neural precursors and their progeny. Experiments indicate that serotonin regulates adult neurogenesis in the crustacean brain by multiple mechanisms: via direct effects of serotonin released from brain neurons into the hemolymph or by local release onto target cells, or by indirect influences via a serotonin-mediated release of agents from other regions, such as hormones from the sinus gland and cytokines from hematopoietic tissues. Evidence in crayfish also indicates that serotonin mediates the attraction of neural precursors generated by the immune system to the neurogenic niche. Thus, studies in the crustacean brain have revealed multiple roles for this monoamine in adult neurogenesis, and identified several pathways by which serotonin influences the generation of new neurons.

Within-category variance and lexical tone discrimination in native and non-native speakers

NARCIS (Netherlands)

Hoffmann, C.W.G.; Sadakata, M.; Chen, A.; Desain, P.W.M.; McQueen, J.M.; Gussenhove, C.; Chen, Y.; Dediu, D.

2014-01-01

In this paper, we show how acoustic variance within lexical tones in disyllabic Mandarin Chinese pseudowords affects discrimination abilities in both native and non-native speakers of Mandarin Chinese. Within-category acoustic variance did not hinder native speakers in discriminating between lexical

Eight nonnative plants in western Oregon forests: associations with environment and management.

Science.gov (United States)

Andrew. Gray

2005-01-01

Nonnative plants have tremendous ecological and economic impacts on plant communities globally, but comprehensive data on the distribution and ecological relationships of individual species is often scarce or nonexistent. The objective of this study was to assess the influence of vegetation type, climate, topography, and management history on the distribution and...

Teaching a Growing a Population of Non-Native English-Speaking Students in American Universities: Cultural and Linguistic Challenges

Directory of Open Access Journals (Sweden)

Maria Cristina Fava

2016-12-01

Full Text Available The increasing number of non-native English speaking students in American universities, mostly from Asian countries, presents unprecedented challenges and calls for an in-depth study on how we teach western art music history. This essay challenges some aspects of liberal multiculturalism and proposes the creation of channels of communication that allow non-native English speaking students to understand the premises of a Eurocentric system of knowledge without undermining their own cultural backgrounds.

Designing acoustics for linguistically diverse classrooms: Effects of background noise, reverberation and talker foreign accent on speech comprehension by native and non-native English-speaking listeners

Science.gov (United States)

Peng, Zhao Ellen

The current classroom acoustics standard (ANSI S12.60-2010) recommends core learning spaces not to exceed background noise level (BNL) of 35 dBA and reverberation time (RT) of 0.6 second, based on speech intelligibility performance mainly by the native English-speaking population. Existing literature has not correlated these recommended values well with student learning outcomes. With a growing population of non-native English speakers in American classrooms, the special needs for perceiving degraded speech among non-native listeners, either due to realistic room acoustics or talker foreign accent, have not been addressed in the current standard. This research seeks to investigate the effects of BNL and RT on the comprehension of English speech from native English and native Mandarin Chinese talkers as perceived by native and non-native English listeners, and to provide acoustic design guidelines to supplement the existing standard. This dissertation presents two studies on the effects of RT and BNL on more realistic classroom learning experiences. How do native and non-native English-speaking listeners perform on speech comprehension tasks under adverse acoustic conditions, if the English speech is produced by talkers of native English (Study 1) versus native Mandarin Chinese (Study 2)? Speech comprehension materials were played back in a listening chamber to individual listeners: native and non-native English-speaking in Study 1; native English, native Mandarin Chinese, and other non-native English-speaking in Study 2. Each listener was screened for baseline English proficiency level, and completed dual tasks simultaneously involving speech comprehension and adaptive dot-tracing under 15 acoustic conditions, comprised of three BNL conditions (RC-30, 40, and 50) and five RT scenarios (0.4 to 1.2 seconds). The results show that BNL and RT negatively affect both objective performance and subjective perception of speech comprehension, more severely for non-native

Toxicity induced by dieldrin and chlorpyrifos in the freshwater crayfish Cambarellus montezumae (Cambaridae

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Sandra Díaz-Barriga Arceo

2015-03-01

Full Text Available The toxicity induced by insecticides in aquatic organisms is of utmost relevance because it may give a clue about the degree of health or damage of the involved ecosystem. In the present report, we determined the effect of dieldrin (DD and chlorpyrifos (CP on the freshwater crayfish, Cambarellus montezumae. The organisms (4-6cm in diameter were collected in the Ignacio Ramírez Reservoir, situated at 50km Northeast of Mexico City, in the Rio Lerma Basin. Initially, we determined the LC50 value with the Probit method, then the DNA damage with single cell gel electrophoresis (comet assay applied at 24, 48, and 72h of exposure to the brain and hepatopancreas of animals exposed (in reconstituted water to 0.05 and 0.5µg/L of each insecticide. In the hepatopancreas of the same organisms, we determined the lipid peroxidation by applying the TBARS test. DNA damage and lipid peroxidation were also evaluated with the same methods to organisms exposed in water from the reservoir. In regard to the LC50 at 72h of exposure, we found a value of 5.1µg/L and a value of 5.62µg/L for DD and CP, respectively. The comet assay applied at different exposure times showed significant DNA damage to both organs, with respect to the control level. In the case of DD, statistical significance was observed for the two doses in the whole evaluated schedule. CP was genotoxic in the brain with the high dose at 72h, and in the hepatopancreas with the two tested doses at all evaluated exposure times. Also, a significant lipid peroxidation increase was detected with the two doses of insecticides. In the study with water from the reservoir, a more pronounced DNA damage was detected. Our results showed strong DNA damage induced by both insecticides in the crayfish, as well as a correlation with the lipid peroxidation effect, suggesting that oxidative stress is involved in the genotoxic alteration. Our results also showed the usefulness of the studied organism as well as the

Relative Weighting of Semantic and Syntactic Cues in Native and Non-Native Listeners' Recognition of English Sentences.

Science.gov (United States)

Shi, Lu-Feng; Koenig, Laura L

2016-01-01

Non-native listeners do not recognize English sentences as effectively as native listeners, especially in noise. It is not entirely clear to what extent such group differences arise from differences in relative weight of semantic versus syntactic cues. This study quantified the use and weighting of these contextual cues via Boothroyd and Nittrouer's j and k factors. The j represents the probability of recognizing sentences with or without context, whereas the k represents the degree to which context improves recognition performance. Four groups of 13 normal-hearing young adult listeners participated. One group consisted of native English monolingual (EMN) listeners, whereas the other three consisted of non-native listeners contrasting in their language dominance and first language: English-dominant Russian-English, Russian-dominant Russian-English, and Spanish-dominant Spanish-English bilinguals. All listeners were presented three sets of four-word sentences: high-predictability sentences included both semantic and syntactic cues, low-predictability sentences included syntactic cues only, and zero-predictability sentences included neither semantic nor syntactic cues. Sentences were presented at 65 dB SPL binaurally in the presence of speech-spectrum noise at +3 dB SNR. Listeners orally repeated each sentence and recognition was calculated for individual words as well as the sentence as a whole. Comparable j values across groups for high-predictability, low-predictability, and zero-predictability sentences suggested that all listeners, native and non-native, utilized contextual cues to recognize English sentences. Analysis of the k factor indicated that non-native listeners took advantage of syntax as effectively as EMN listeners. However, only English-dominant bilinguals utilized semantics to the same extent as EMN listeners; semantics did not provide a significant benefit for the two non-English-dominant groups. When combined, semantics and syntax benefitted EMN

Why Not Non-Native Varieties of English as Listening Comprehension Test Input?

Science.gov (United States)

Abeywickrama, Priyanvada

2013-01-01

The existence of different varieties of English in target language use (TLU) domains calls into question the usefulness of listening comprehension tests whose input is limited only to a native speaker variety. This study investigated the impact of non-native varieties or accented English speech on test takers from three different English use…

Long-distance dispersal of non-native pine bark beetles from host resources

Science.gov (United States)

Kevin Chase; Dave Kelly; Andrew M. Liebhold; Martin K.-F. Bader; Eckehard G. Brockerhoff

2017-01-01

Dispersal and host detection are behaviours promoting the spread of invading populations in a landscape matrix. In fragmented landscapes, the spatial arrangement of habitat structure affects the dispersal success of organisms. The aim of the present study was to determine the long distance dispersal capabilities of two non-native pine bark beetles (Hylurgus...

Topic Continuity in Informal Conversations between Native and Non-Native Speakers of English

Science.gov (United States)

Morris-Adams, Muna

2013-01-01

Topic management by non-native speakers (NNSs) during informal conversations has received comparatively little attention from researchers, and receives surprisingly little attention in second language learning and teaching. This article reports on one of the topic management strategies employed by international students during informal, social…

Short-Term Response of Native Flora to the Removal of Non-Native Shrubs in Mixed-Hardwood Forests of Indiana, USA

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Joshua M. Shields

2015-05-01

Full Text Available While negative impacts of invasive species on native communities are well documented, less is known about how these communities respond to the removal of established populations of invasive species. With regard to invasive shrubs, studies examining native community response to removal at scales greater than experimental plots are lacking. We examined short-term effects of removing Lonicera maackii (Amur honeysuckle and other non-native shrubs on native plant taxa in six mixed-hardwood forests. Each study site contained two 0.64 ha sample areas—an area where all non-native shrubs were removed and a reference area where no treatment was implemented. We sampled vegetation in the spring and summer before and after non-native shrubs were removed. Cover and diversity of native species, and densities of native woody seedlings, increased after shrub removal. However, we also observed significant increases in L. maackii seedling densities and Alliaria petiolata (garlic mustard cover in removal areas. Changes in reference areas were less pronounced and mostly non-significant. Our results suggest that removing non-native shrubs allows short-term recovery of native communities across a range of invasion intensities. However, successful restoration will likely depend on renewed competition with invasive species that re-colonize treatment areas, the influence of herbivores, and subsequent control efforts.

Diel turbidity cycles in a headwater stream: evidence of nocturnal bioturbation?

OpenAIRE

Cooper, Richard J.; Outram, Faye; Hiscock, Kevin M.

2016-01-01

Purpose: A small number of recent studies have linked daily cycles in stream turbidity to nocturnal bioturbation by aquatic fauna, principally crayfish, and demonstrated this process can significantly impact upon water quality under baseflow conditions. Adding to this limited body of research, we use high-resolution water quality monitoring data to investigate evidence of diel turbidity cycles in a lowland, headwater stream with a known signal crayfish (Pacifastacus leniusculus) population an...

Recovery of Hafnia alvei from diseased brown trout, Salmo trutta L., and healthy noble crayfish, Astacus astacus (L.), in Bulgaria.

Science.gov (United States)

Orozova, P; Sirakov, I; Chikova, V; Popova, R; Al-Harbi, A H; Crumlish, M; Austin, B

2014-10-01

Hafnia alvei was isolated in Bulgaria from healthy noble crayfish, Astacus astacus (L.), and then from farmed diseased brown trout, Salmo trutta L., with signs of haemorrhagic septicaemia. The isolates were identified initially with conventional phenotyping and commercial Merlin Micronaut and API 20E rapid identification systems, followed by sequencing of the 16S rRNA gene. Hafnia alvei Bt1, Bt2 and Aa4 were of low virulence to rainbow trout and brown trout, although cytotoxicity was demonstrated by Bt1 and Bt2, but not by Aa4. © 2014 John Wiley & Sons Ltd.

AlphaScreen-based homogeneous assay using a pair of 25-residue artificial proteins for high-throughput analysis of non-native IgG.

Science.gov (United States)

Senga, Yukako; Imamura, Hiroshi; Miyafusa, Takamitsu; Watanabe, Hideki; Honda, Shinya

2017-09-29

Therapeutic IgG becomes unstable under various stresses in the manufacturing process. The resulting non-native IgG molecules tend to associate with each other and form aggregates. Because such aggregates not only decrease the pharmacological effect but also become a potential risk factor for immunogenicity, rapid analysis of aggregation is required for quality control of therapeutic IgG. In this study, we developed a homogeneous assay using AlphaScreen and AF.2A1. AF.2A1 is a 25-residue artificial protein that binds specifically to non-native IgG generated under chemical and physical stresses. This assay is performed in a short period of time. Our results show that AF.2A1-AlphaScreen may be used to evaluate the various types of IgG, as AF.2A1 recognizes the non-native structure in the constant region (Fc region) of IgG. The assay was effective for detection of non-native IgG, with particle size up to ca. 500 nm, generated under acid, heat, and stirring conditions. In addition, this technique is suitable for analyzing non-native IgG in CHO cell culture supernatant and mixed with large amounts of native IgG. These results indicate the potential of AF.2A1-AlphaScreen to be used as a high-throughput evaluation method for process monitoring as well as quality testing in the manufacturing of therapeutic IgG.

Professional Development in Japanese Non-Native English Speaking Teachers' Identity and Efficacy

Science.gov (United States)

Takayama, Hiromi

2015-01-01

This mixed methods study investigates how Japanese non-native English speaking teachers' (NNESTs) efficacy and identity are developed and differentiated from those of native English speaking teachers (NESTs). To explore NNESTs' efficacy, this study focuses on the contributing factors, such as student engagement, classroom management, instructional…

Occurrence and spread of nonnative invasive plants in stands treated with fire and/or mechanical treatments in the upper piedmont of South Carolina

Science.gov (United States)

Ross J. Phillips; Thomas A. Waldrop; Aaron D. Stottlemyer

2013-01-01

Increasing numbers of nonnative invasive plant species and the expansion of existing nonnative plant populations provide challenges for land managers trying to achieve commercial and restoration goals. Some methods used to achieve these goals, e.g., prescribed fire and mechanical treatments, may result in disturbances that promote the establishment and spread of...

Recreational freshwater fishing drives non-native aquatic species richness patterns at a continental scale.

Science.gov (United States)

Mapping the geographic distribution of non-native aquatic species is a critically important precursor to understanding the anthropogenic and environmental factors that drive freshwater biological invasions. Such efforts are often limited to local scales and/or to single species, ...

Student perceptions of native and non-native speaker language instructors: A comparison of ESL and Spanish

Directory of Open Access Journals (Sweden)

Laura Callahan

2006-12-01

Full Text Available The question of the native vs. non-native speaker status of second and foreign language instructors has been investigated chiefly from the perspective of the teacher. Anecdotal evidence suggests that students have strong opinions on the relative qualities of instruction by native and non-native speakers. Most research focuses on students of English as a foreign or second language. This paper reports on data gathered through a questionnaire administered to 55 university students: 31 students of Spanish as FL and 24 students of English as SL. Qualitative results show what strengths students believe each type of instructor has, and quantitative results confirm that any gap students may perceive between the abilities of native and non-native instructors is not so wide as one might expect based on popular notions of the issue. ESL students showed a stronger preference for native-speaker instructors overall, and were at variance with the SFL students' ratings of native-speaker instructors' performance on a number of aspects. There was a significant correlation in both groups between having a family member who is a native speaker of the target language and student preference for and self-identification with a native speaker as instructor. (English text

Emotional communication in medical consultations with native and non-native patients applying two different methodological approaches.

Science.gov (United States)

Kale, Emine; Skjeldestad, Kristin; Finset, Arnstein

2013-09-01

To explore the potential agreement between two different methods to investigate emotional communication of native and non-native patients in medical consultations. The data consisted of 12 videotaped hospital consultations with six native and six non-native patients. The consultations were coded according to coding rules of the Verona Coding definitions of Emotional Sequences (VR-CoDES) and afterwards analyzed by discourse analysis (DA) by two co-workers who were blind to the results from VR-CoDES. The agreement between VR-CoDES and DA was high in consultations with many cues and concerns, both with native and non-native patients. In consultations with no (or one cue) according to VR-CoDES criteria the DA still indicated the presence of emotionally salient expressions and themes. In some consultations cues to underlying emotions are communicated so vaguely or veiled by language barriers that standard VR-CoDES coding may miss subtle cues. Many of these sub-threshold cues could potentially be coded as cues according to VR-CoDES main coding categories, if criteria for coding vague or ambiguous cues had been better specified. Combining different analytical frameworks on the same dataset provide us new insights on emotional communication. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

User requirement analysis of social conventions learning applications for Non-natives and low-literates

NARCIS (Netherlands)

Schouten, D.; Smets, N.; Driessen, M.; Hanekamp, M.; Cremers, A.H.M.; Neerincx, M.A.

2013-01-01

Learning and acting on social conventions is problematic for low-literates and non-natives, causing problems with societal participation and citizenship. Using the Situated Cognitive Engineering method, requirements for the design of social conventions learning software are derived from demographic

Non-Native Speakers of the Language of Instruction: Self-Perceptions of Teaching Ability

Science.gov (United States)

Samuel, Carolyn

2017-01-01

Given the linguistically diverse instructor and student populations at Canadian universities, mutually comprehensible oral language may not be a given. Indeed, both instructors who are non-native speakers of the language of instruction (NNSLIs) and students have acknowledged oral communication challenges. Little is known, though, about how the…

Patterns of hybridization of nonnative cutthroat trout and hatchery rainbow trout with native redband trout in the Boise River, Idaho

Science.gov (United States)

Neville, Helen M.; Dunham, Jason B.

2011-01-01

Hybridization is one of the greatest threats to native fishes. Threats from hybridization are particularly important for native trout species as stocking of nonnative trout has been widespread within the ranges of native species, thus increasing the potential for hybridization. While many studies have documented hybridization between native cutthroat trout Oncorhynchus clarkii and nonnative rainbow trout O. mykiss, fewer have focused on this issue in native rainbow trout despite widespread threats from introductions of both nonnative cutthroat trout and hatchery rainbow trout. Here, we describe the current genetic (i.e., hybridization) status of native redband trout O. mykiss gairdneri populations in the upper Boise River, Idaho. Interspecific hybridization was widespread (detected at 14 of the 41 sampled locations), but high levels of hybridization between nonnative cutthroat trout and redband trout were detected in only a few streams. Intraspecific hybridization was considerably more widespread (almost 40% of sampled locations), and several local populations of native redband trout have been almost completely replaced with hatchery coastal rainbow trout O. mykiss irideus; other populations exist as hybrid swarms, some are in the process of being actively invaded, and some are maintaining genetic characteristics of native populations. The persistence of some redband trout populations with high genetic integrity provides some opportunity to conserve native genomes, but our findings also highlight the complex decisions facing managers today. Effective management strategies in this system may include analysis of the specific attributes of each site and population to evaluate the relative risks posed by isolation versus maintaining connectivity, identifying potential sites for control or eradication of nonnative trout, and long-term monitoring of the genetic integrity of remaining redband trout populations to track changes in their status.

Increasing Potential Risk of a Global Aquatic Invader in Europe in Contrast to Other Continents under Future Climate Change

Science.gov (United States)

Liu, Xuan; Guo, Zhongwei; Ke, Zunwei; Wang, Supen; Li, Yiming

2011-01-01

Background Anthropogenically-induced climate change can alter the current climatic habitat of non-native species and can have complex effects on potentially invasive species. Predictions of the potential distributions of invasive species under climate change will provide critical information for future conservation and management strategies. Aquatic ecosystems are particularly vulnerable to invasive species and climate change, but the effect of climate change on invasive species distributions has been rather neglected, especially for notorious global invaders. Methodology/Principal Findings We used ecological niche models (ENMs) to assess the risks and opportunities that climate change presents for the red swamp crayfish (Procambarus clarkii), which is a worldwide aquatic invasive species. Linking the factors of climate, topography, habitat and human influence, we developed predictive models incorporating both native and non-native distribution data of the crayfish to identify present areas of potential distribution and project the effects of future climate change based on a consensus-forecast approach combining the CCCMA and HADCM3 climate models under two emission scenarios (A2a and B2a) by 2050. The minimum temperature from the coldest month, the human footprint and precipitation of the driest quarter contributed most to the species distribution models. Under both the A2a and B2a scenarios, P. clarkii shifted to higher latitudes in continents of both the northern and southern hemispheres. However, the effect of climate change varied considerately among continents with an expanding potential in Europe and contracting changes in others. Conclusions/Significance Our findings are the first to predict the impact of climate change on the future distribution of a globally invasive aquatic species. We confirmed the complexities of the likely effects of climate change on the potential distribution of globally invasive species, and it is extremely important to develop

STUDENTS WRITING EMAILS TO FACULTY: AN EXAMINATION OF E-POLITENESS AMONG NATIVE AND NON-NATIVE SPEAKERS OF ENGLISH

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Sigrun Biesenbach-Lucas

2007-02-01

Full Text Available This study combines interlanguage pragmatics and speech act research with computer-mediated communication and examines how native and non-native speakers of English formulate low- and high-imposition requests to faculty. While some research claims that email, due to absence of non-verbal cues, encourages informal language, other research has claimed the opposite. However, email technology also allows writers to plan and revise messages before sending them, thus affording the opportunity to edit not only for grammar and mechanics, but also for pragmatic clarity and politeness.The study examines email requests sent by native and non-native English speaking graduate students to faculty at a major American university over a period of several semesters and applies Blum-Kulka, House, and Kasper’s (1989 speech act analysis framework – quantitatively to distinguish levels of directness, i.e. pragmatic clarity; and qualitatively to compare syntactic and lexical politeness devices, the request perspectives, and the specific linguistic request realization patterns preferred by native and non-native speakers. Results show that far more requests are realized through direct strategies as well as hints than conventionally indirect strategies typically found in comparative speech act studies. Politeness conventions in email, a text-only medium with little guidance in the academic institutional hierarchy, appear to be a work in progress, and native speakers demonstrate greater resources in creating e-polite messages to their professors than non-native speakers. A possible avenue for pedagogical intervention with regard to instruction in and acquisition of politeness routines in hierarchically upward email communication is presented.

Locking horns with Hawai‘i’s non-native ungulate issues

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Hess, Steve

2014-01-01

Conservation and management interests for sustained-yield hunting of non-native ungulates in Hawai‘i have conflicted with the conservation of native biota for several decades. Hawaiian ecosystems evolved in the absence of large mammals and all currently hunted animals in Hawai‘i are non-native species. The best-studied aspects of Hawai‘i’s ungulates have dealt primarily with direct negative effects on native biota in natural areas, but there has been little research in population dynamics for sustained-yield management. Ungulates have been removed from approximately 750 km2 throughout the Hawaiian Islands to protect these natural areas, thereby reducing the amount of land area available for hunting activities and the maintenance of game populations. At the same time, unauthorized introductions of additional wild ungulate species between Hawaiian Islands have recently increased in frequency. The majority of hunting activities are of feral domestic livestock species for subsistence purposes, which typically do not generate sufficient revenue to offset costs of game management. Moreover, bag limits and seasons are generally not determined from biological criteria because harvest reporting is voluntary and game populations are rarely monitored. Consequently, ungulate populations cannot be managed for any particular level of abundance or other objectives. Research and monitoring which emphasize population dynamics and productivity would enable more precisely regulated sustained-yield game management programs and may reduce potential conflicts with the conservation of native biota.

Two new species of freshwater crayfish of the genus Faxonius (Decapoda: Cambaridae) from the Ozark Highlands of Arkansas and Missouri.

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Fetzner, James W Jr; Taylor, Christopher A

2018-03-22

Two new species of freshwater crayfish are described from the Ozarks Plateau of northern Arkansas and southern Missouri. Both species are restricted to the mainstem of rocky streams that are at least fourth-order or greater in size. Recent genetic and morphological investigations of the coldwater crayfish, Faxonius eupunctus Williams, 1952, indicated that it was actually composed of several undescribed species. Faxonius eupunctus is herein restricted to just the Eleven Point River system. Faxonius roberti, new species is found in the mainstem of the Spring and Strawberry river systems in northern Arkansas. It differs from F. eupunctus by lacking a male Form-I gonopod with a distal spatulate mesial process, and presence of two spines on the dorsal side of the merus, where F. eupunctus typically has 1 spine. Faxonius wagneri, new species is known from a 54 mile (86 km) stretch of the Eleven Point River mainstem, ranging from just southeast of Greer, Missouri to just north of Birdell, Arkansas. Faxonius wagneri can be differentiated from both F. eupunctus and Faxonius roberti sp. nov. by using the male Form-I and Form-II gonopods, the shape of the chelae, and the female annulus ventralis. In F. wagneri, the terminal elements of the first pleopod are almost twice as long as those in F. eupunctus and F. roberti, with the tips of the appendage reaching the posterior base of the first perieopod when the abdomen is flexed forward, whereas, in the other two species, these elements only reach the base of the second pereiopod. The species also possesses two spines on the dorsal side of the merus of the first pereiopod, which helps distinguish it from F. eupunctus.

History of nonnative Monk Parakeets in Mexico.

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Hobson, Elizabeth A; Smith-Vidaurre, Grace; Salinas-Melgoza, Alejandro

2017-01-01

Nonnative Monk Parakeets have been reported in increasing numbers across many cities in Mexico, and were formally classified as an invasive species in Mexico in late 2016. However, there has not been a large-scale attempt to determine how international pet trade and national and international governmental regulations have played a part in colonization, and when the species appeared in different areas. We describe the changes in regulations that led the international pet trade market to shift to Mexico, then used international trade data to determine how many parakeets were commercially imported each year and where those individuals originated. We also quantified the recent increases in Monk Parakeet (Myiopsitta monachus) sightings in Mexico in both the scientific literature and in citizen science reports. We describe the timeline of increased reports to understand the history of nonnative Monk Parakeets in Mexico. As in other areas where the species has colonized, the main mode of transport is through the international pet trade. Over half a million Monk Parakeets were commercially imported to Mexico during 2000-2015, with the majority of importation (90%) occurring in 2008-2014, and almost all (98%) were imported from Uruguay. The earliest record of a free-flying Monk Parakeet was observed during 1994-1995 in Mexico City, but sightings of the parakeets did not become geographically widespread in either the scientific literature or citizen science databases until 2012-2015. By 2015, parakeets had been reported in 97 cities in Mexico. Mexico City has consistently seen steep increases in reporting since this species was first reported in Mexico. Here we find that both national and international legal regulations and health concerns drove a rise and fall in Monk Parakeet pet trade importations, shortly followed by widespread sightings of feral parakeets across Mexico. Further monitoring of introduced Monk Parakeet populations in Mexico is needed to understand the

Vulnerability of freshwater native biodiversity to non-native species invasions across the continental United States

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Background/Question/Methods Non-native species pose one of the greatest threats to native biodiversity. The literature provides plentiful empirical and anecdotal evidence of this phenomenon; however, such evidence is limited to local or regional scales. Employing geospatial analy...

Non-Native (Exotic) Snake Envenomations in the U.S., 2005–2011

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Warrick, Brandon J.; Boyer, Leslie V.; Seifert, Steven A.

2014-01-01

Non-native (exotic) snakes are a problematic source of envenomation worldwide. This manuscript describes the current demographics, outcomes and challenges of non-native snakebites in the United States (U.S.). We performed a retrospective case series of the National Poison Data System (NPDS) database between 2005 and 2011. There were 258 human exposures involving at least 61 unique exotic venomous species (average = 37 per year; range = 33–40). Males comprised 79% and females 21%. The average age was 33 years with 16% less than 20 years old. 70% of bites occurred in a private residence and 86% were treated at a healthcare facility. 35% of cases received antivenom and 10% were given antibiotics. This study is compared to our previous study (1994–2004) in which there was a substantial coding error rate. Software modifications significantly reduced coding errors. Identification and acquisition of appropriate antivenoms pose a number of logistical difficulties in the management of these envenomations. In the U.S., poison centers have valuable systems and clinical roles in the provision of expert consultation and in the management of these cases. PMID:25268980

Non-Native (Exotic Snake Envenomations in the U.S., 2005–2011

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Brandon J. Warrick

2014-09-01

Full Text Available Non-native (exotic snakes are a problematic source of envenomation worldwide. This manuscript describes the current demographics, outcomes and challenges of non-native snakebites in the United States (U.S.. We performed a retrospective case series of the National Poison Data System (NPDS database between 2005 and 2011. There were 258 human exposures involving at least 61 unique exotic venomous species (average = 37 per year; range = 33–40. Males comprised 79% and females 21%. The average age was 33 years with 16% less than 20 years old. 70% of bites occurred in a private residence and 86% were treated at a healthcare facility. 35% of cases received antivenom and 10% were given antibiotics. This study is compared to our previous study (1994–2004 in which there was a substantial coding error rate. Software modifications significantly reduced coding errors. Identification and acquisition of appropriate antivenoms pose a number of logistical difficulties in the management of these envenomations. In the U.S., poison centers have valuable systems and clinical roles in the provision of expert consultation and in the management of these cases.

Minimal effectiveness of native and non-native seeding following three high-severity wildfire

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Ken A. Stella; Carolyn H. Sieg; Pete Z. Fule

2010-01-01

The rationale for seeding following high-severity wildfires is to enhance plant cover and reduce bare ground, thus decreasing the potential for soil erosion and non-native plant invasion. However, experimental tests of the effectiveness of seeding in meeting these objectives in forests are lacking. We conducted three experimental studies of the effectiveness of seeding...

Which English? Whose English? An Investigation of "Non-Native" Teachers' Beliefs about Target Varieties

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Young, Tony Johnstone; Walsh, Steve

2010-01-01

This study explored the beliefs of "non-native English speaking" teachers about the usefulness and appropriacy of varieties such as English as an International Language (EIL) and English as a Lingua Franca (ELF), compared with native speaker varieties. The study therefore addresses the current theoretical debate concerning "appropriate" target…

Non-native fish introductions and the reversibility of amphibian declines in the Sierra Nevada

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Roland A. Knapp

2004-01-01

Amphibians are declining worldwide for a variety of reasons, including habitat alteration, introduction of non-native species, disease, climate change, and environmental contaminants. Amphibians often play important roles in structuring ecosystems, and, as a result, amphibian population declines or extinctions are likely to affect other trophic levels (Matthews and...

The assessment of the habitat and water quality requirements of the stone crayfish (Austropotamobius torrentium and noble crayfish (Astacus astacus species in the rivers from the Anina Mountains (SW Romania

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Pârvulescu L.

2011-02-01

Full Text Available The species Austropotamobius torrentium and Astacus astacus are two species known in the EU directives to require deeper understanding of their autecologic requirements before any sustainable conservation effort could be successfully applied. Therefore, the paper aims to analyze the occurrence of these two species of crayfish in the Anina Mountains (Romania in relation to several physical-chemical indicators measured on site. The results suggest that the anthropogenic impacts registered in some of the sampling sites (e.g. organic pollution and river bed modification might have triggered the disappearance of both species from the areas of the water sheds situated downstream villages and towns, deforestation sites and sewage treatment plants. The analysis suggest that both species might have similar ecologic requirements, with a BMWP score of 8 (out of a possible 10, therefore good indicators of pristine aquatic environments and with a possible toleration to pollution but only up to a moderate level. Nevertheless, the lack of cohabitation of the populations of both species at a local scale was discussed along with two possible explaining hypotheses: behavioral exclusion or different times and/or modalities of dispersal history.

Regional patterns of major nonnative invasive plants and associated factors in upper Midwest forests

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Zhaofei Fan; W. Keith Moser; Mark H. Hansen; Mark D. Nelson

2013-01-01

Nonnative invasive plants (IPs) are rapidly spreading into natural ecosystems (e.g., forests and grasslands). Potential threats of IP invasion into natural ecosystems include biodiversity loss, structural and environmental change, habitat degradation, and economic losses. The Upper Midwest of the United States encompasses the states of Illinois, Indiana, Iowa, Michigan...

Differences in the Metacognitive Awareness of Reading Strategies among Native and Non-Native Readers.

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Sheorey, R.; Mokhtari, K.

2001-01-01

Examines the differences in the reported use of reading strategies of native and non-native English speakers when reading academic materials. Participants were native English speaking and English-as-a-Second-Language college students who completed a survey of reading strategies aimed at discerning the strategies readers report using when coping…

The Knowledge Base of Non-Native English-Speaking Teachers: Perspectives of Teachers and Administrators

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Zhang, Fengjuan; Zhan, Ju

2014-01-01

This study explores the knowledge base of non-native English-speaking teachers (NNESTs) working in the Canadian English as a second language (ESL) context. By examining NNESTs' experiences in seeking employment and teaching ESL in Canada, and investigating ESL program administrators' perceptions and hiring practices in relation to NNESTs, it…

Versatility of non-native forms of human cytochrome c: pH and micellar concentration dependence.

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Simon, Matthieu; Metzinger-Le Meuth, Valérie; Chevance, Soizic; Delalande, Olivier; Bondon, Arnaud

2013-01-01

In addition to its electron transfer activity, cytochrome c is now known to trigger apoptosis via peroxidase activity. This new function is related to a structural modification of the cytochrome upon association with anionic lipids, particularly cardiolipin present in the mitochondrial membrane. However, the exact nature of the non-native state induced by this interaction remains an active subject of debate. In this work, using human cytochromes c (native and two single-histidine mutants and the corresponding double mutant) and micelles as a hydrophobic medium, we succeeded, through UV-visible spectroscopy, circular dichroism spectroscopy and NMR spectroscopy, in fully characterizing the nature of the sixth ligand replacing the native methionine. Furthermore, careful pH titrations permitted the identification of the amino acids involved in the iron binding over a range of pH values. Replacement of the methionine by lysine was only observed at pH above 8.5, whereas histidine binding is dependent on both pH and micelle concentration. The pH variation range for histidine protonation is relatively narrow and is consistent with the mitochondrial intermembrane pH changes occurring during apoptosis. These results allow us to rule out lysine as the sixth ligand at pH values close to neutrality and reinforce the role of histidines (preferentially His33 vs. His26) as the main candidate to replace methionine in the non-native cytochrome c. Finally, on the basis of these results and molecular dynamics simulations, we propose a 3D model for non-native cytochrome c in a micellar environment.

Characterization of Population Genetic Structure of red swamp crayfish, Procambarus clarkii, in China.

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Yi, Shaokui; Li, Yanhe; Shi, Linlin; Zhang, Long; Li, Qingbin; Chen, Jing

2018-04-03

The red swamp crayfish (Procambarus clarkii) is one of the most economically important farmed aquatic species in China. However, it is also a famous invasive species in the world. This invasive species was dispersed most via human activities including intentional or unintentional carry in China. Thus, P. clarkii naturally distributed in China provides us a desirable mode to investigate the genetic structure of an invasive species dispersed mainly by human-mediated factors. To reveal the impact of human-mediated dispersal on genetic structure of P. clarkii in China, a total of 22,043 genome-wide SNPs were obtained from approximately 7.4 billion raw reads using 2b-RAD technique in this study. An evident pattern of population genetic structure and the asymmetrical migrational rates between different regions were observed with 22 populations based on these SNPs. This study provide a better understanding of the population genetic structure and demographic history of P. clarkii populations in China, inferring that anthropogenic factors (aquaculture or by accident) and ecological factors (e.g., complicated topography and climatic environment), as well as its special biological traits could account for the current population structure pattern and dispersal history of P. clarkii.

Impacts of nonnative invasive species on US forests and recommendations for policy and management

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W. Keith Moser; Edward L. Barnard; Ronald F. Billings; Susan J. Crocker; Andrew N. Gray; George G. Ice; Mee-Sook Kim; Richard Reid; Sue U. Rodman; William H. McWilliams

2009-01-01

The introduction of nonnative invasive species (NNIS) into the United States has had tremendous impacts on the nation's commercial and urban forest resources. Of principal concern are the effects of NNIS on forest composition, structure, function, productivity, and patterns of carbon sequestration. In 2006, the Society of American Foresters commissioned an ad hoc...

Invasions by two non-native insects alter regional forest species composition and successional trajectories

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Randall S. Morin; Andrew M. Liebhold

2015-01-01

While invasions of individual non-native phytophagous insect species are known to affect growth and mortality of host trees, little is known about how multiple invasions combine to alter forest dynamics over large regions. In this study we integrate geographical data describing historical invasion spread of the hemlock woolly adelgid, Adelges tsugae...

UV Screening in Native and Non-native Plant Species in the Tropical Alpine: Implications for Climate Change-Driven Migration of Species to Higher Elevations

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Paul W. Barnes

2017-08-01

Full Text Available Ongoing changes in Earth’s climate are shifting the elevation ranges of many plant species with non-native species often experiencing greater expansion into higher elevations than native species. These climate change-induced shifts in distributions inevitably expose plants to novel biotic and abiotic environments, including altered solar ultraviolet (UV-B (280–315 nm radiation regimes. Do the greater migration potentials of non-native species into higher elevations imply that they have more effective UV-protective mechanisms than native species? In this study, we surveyed leaf epidermal UV-A transmittance (TUV A in a diversity of plant species representing different growth forms to test whether native and non-native species growing above 2800 m elevation on Mauna Kea, Hawaii differed in their UV screening capabilities. We further compared the degree to which TUV A varied along an elevation gradient in the native shrub Vaccinium reticulatum and the introduced forb Verbascum thapsus to evaluate whether these species differed in their abilities to adjust their levels of UV screening in response to elevation changes in UV-B. For plants growing in the Mauna Kea alpine/upper subalpine, we found that adaxial TUV A, measured with a UVA-PAM fluorometer, varied significantly among species but did not differ between native (mean = 6.0%; n = 8 and non-native (mean = 5.8%; n = 11 species. When data were pooled across native and non-native taxa, we also found no significant effect of growth form on TUV A, though woody plants (shrubs and trees were represented solely by native species whereas herbaceous growth forms (grasses and forbs were dominated by non-native species. Along an elevation gradient spanning 2600–3800 m, TUV A was variable (mean range = 6.0–11.2% and strongly correlated with elevation and relative biologically effective UV-B in the exotic V. thapsus; however, TUV A was consistently low (3% and did not vary with elevation in the native

Long-term trends of native and non-native fish faunas in the American Southwest

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Olden, J. D.

2005-06-01

Full Text Available Environmental degradation and the proliferation of non-native fish species threaten the endemic, and highly unique fish faunas of the American Southwest. The present study examines long-term trends (> 160 years of fish species distributions in the Lower Colorado River Basin and identifies those native species (n = 28 exhibiting the greatest rates of decline and those non-native species (n = 48 exhibiting the highest rates of spread. Among the fastest expanding invaders in the basin are red shiner (Cyprinella lutrensis, fathead minnow (Pimephales promelas, green sunfish (Lepomis cyanellus, largemouth bass (Micropterus salmoides, western mosquitofish (Gambussia affinis and channel catfish (Ictalurus punctatus; species considered to be the most invasive in terms of their negative impacts on native fish communities. Interestingly, non-native species that have been recently introduced (1950+ have generally spread at substantially lower rates as compared to species introduced prior to this time (especially from 1920 to 1950, likely reflecting reductions in human-aided spread of species. We found general agreement between patterns of species decline and extant distribution sizes and official listing status under the U.S. Endangered Species Act. ‘Endangered’ species have generally experienced greater declines and have smaller present-day distributions compared to ‘threatened’ species, which in turn have shown greater declines and smaller distributions than those species not currently listed. A number of notable exceptions did exist, however, and these may provide critical information to help guide the future listing of species (i.e., identification of candidates and the upgrading or downgrading of current listed species that are endemic to the Lower Colorado River Basin. The strong correlation between probability estimates of local extirpation and patterns of native species decline and present-day distributions suggest a possible proactive

Decoding speech perception by native and non-native speakers using single-trial electrophysiological data.

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Alex Brandmeyer

Full Text Available Brain-computer interfaces (BCIs are systems that use real-time analysis of neuroimaging data to determine the mental state of their user for purposes such as providing neurofeedback. Here, we investigate the feasibility of a BCI based on speech perception. Multivariate pattern classification methods were applied to single-trial EEG data collected during speech perception by native and non-native speakers. Two principal questions were asked: 1 Can differences in the perceived categories of pairs of phonemes be decoded at the single-trial level? 2 Can these same categorical differences be decoded across participants, within or between native-language groups? Results indicated that classification performance progressively increased with respect to the categorical status (within, boundary or across of the stimulus contrast, and was also influenced by the native language of individual participants. Classifier performance showed strong relationships with traditional event-related potential measures and behavioral responses. The results of the cross-participant analysis indicated an overall increase in average classifier performance when trained on data from all participants (native and non-native. A second cross-participant classifier trained only on data from native speakers led to an overall improvement in performance for native speakers, but a reduction in performance for non-native speakers. We also found that the native language of a given participant could be decoded on the basis of EEG data with accuracy above 80%. These results indicate that electrophysiological responses underlying speech perception can be decoded at the single-trial level, and that decoding performance systematically reflects graded changes in the responses related to the phonological status of the stimuli. This approach could be used in extensions of the BCI paradigm to support perceptual learning during second language acquisition.

Trophic relationships of small nonnative fishes in a natural creek and several agricultural drains flowing into the Salton Sea, and their potential, effects on the endangered desert pupfish

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Martin, Barbara A.; Saiki, Michael K.

2009-01-01

This study was conducted to characterize trophic relationships of small nonnative fishes and to determine if predation by these fishes contributes to the decline of desert pupfish (Cyprinodon macularius), an endangered cyprinodont on the verge of extinction. We sampled 403 hybrid Mozambique tilapias (Oreochromis mossambica by O. urolepis), 107 redbelly tilapias (Tilapia zillii), 32 longjaw mudsuckers (Gillkhthys mirabilis), 182 western mosquitofish (Gambusia affinis), 222 sailfin mollies (Poecilia latipinna), 63 shortfin mollies (Poecilia mexicana), and 235 porthole livebearers (Poecilurpsis gracilis) from a natural creek and four agricultural drains during September 1999- December 2001. Evidence of piscivory was in gastrointestinal contents of 14 hybrid Mozambique tilapias, 3 redbelly tilapias, 10 longjaw mudsuckers, 8 western mosquitofish, 2 sailfin mollies, and 8 porthole livebearers. Although digestion often was too advanced for identification of fishes consumed by nonnative fishes, remains of desert pupfish were in gastrointestinal contents of a longjaw mudsucker. Our findings, along with Field evidence from other studies that inverse relationships exist between abundances of desert pupfish and nonnative species, are consistent with the hypothesis that predation by nonnative species is contributing to decline of desert pupfish. We suspect that competitive interactions with nonnative fishes might also adversely affect abundance of desert pupfish.

Disadvantages of publishing biomedical research articles in English for non-native speakers of English

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Mohsen Rezaeian

2015-05-01

Full Text Available OBJECTIVES: English has become the most frequently used language for scientific communication in the biomedical field. Therefore, scholars from all over the world try to publish their findings in English. This trend has a number of advantages, along with several disadvantages. METHODS: In the current article, the most important disadvantages of publishing biomedical research articles in English for non-native speakers of English are reviewed. RESULTS: The most important disadvantages of publishing biomedical research articles in English for non-native speakers may include: Overlooking, either unintentionally or even deliberately, the most important local health problems; failure to carry out groundbreaking research due to limited medical research budgets; violating generally accepted codes of publication ethics and committing research misconduct and publications in open-access scam/predatory journals rather than prestigious journals. CONCLUSIONS: The above mentioned disadvantages could eventually result in academic establishments becoming irresponsible or, even worse, corrupt. In order to avoid this, scientists, scientific organizations, academic institutions, and scientific associations all over the world should design and implement a wider range of collaborative and comprehensive plans.

Adaptive Communication: Languages with More Non-Native Speakers Tend to Have Fewer Word Forms.

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Christian Bentz

Full Text Available Explaining the diversity of languages across the world is one of the central aims of typological, historical, and evolutionary linguistics. We consider the effect of language contact-the number of non-native speakers a language has-on the way languages change and evolve. By analysing hundreds of languages within and across language families, regions, and text types, we show that languages with greater levels of contact typically employ fewer word forms to encode the same information content (a property we refer to as lexical diversity. Based on three types of statistical analyses, we demonstrate that this variance can in part be explained by the impact of non-native speakers on information encoding strategies. Finally, we argue that languages are information encoding systems shaped by the varying needs of their speakers. Language evolution and change should be modeled as the co-evolution of multiple intertwined adaptive systems: On one hand, the structure of human societies and human learning capabilities, and on the other, the structure of language.

Disadvantages of publishing biomedical research articles in English for non-native speakers of English.

Science.gov (United States)

Rezaeian, Mohsen

2015-01-01

English has become the most frequently used language for scientific communication in the biomedical field. Therefore, scholars from all over the world try to publish their findings in English. This trend has a number of advantages, along with several disadvantages. In the current article, the most important disadvantages of publishing biomedical research articles in English for non-native speakers of English are reviewed. The most important disadvantages of publishing biomedical research articles in English for non-native speakers may include: Overlooking, either unintentionally or even deliberately, the most important local health problems; failure to carry out groundbreaking research due to limited medical research budgets; violating generally accepted codes of publication ethics and committing research misconduct and publications in open-access scam/predatory journals rather than prestigious journals. The above mentioned disadvantages could eventually result in academic establishments becoming irresponsible or, even worse, corrupt. In order to avoid this, scientists, scientific organizations, academic institutions, and scientific associations all over the world should design and implement a wider range of collaborative and comprehensive plans.

Adaptive Communication: Languages with More Non-Native Speakers Tend to Have Fewer Word Forms

Science.gov (United States)

Bentz, Christian; Verkerk, Annemarie; Kiela, Douwe; Hill, Felix; Buttery, Paula

2015-01-01

Explaining the diversity of languages across the world is one of the central aims of typological, historical, and evolutionary linguistics. We consider the effect of language contact-the number of non-native speakers a language has-on the way languages change and evolve. By analysing hundreds of languages within and across language families, regions, and text types, we show that languages with greater levels of contact typically employ fewer word forms to encode the same information content (a property we refer to as lexical diversity). Based on three types of statistical analyses, we demonstrate that this variance can in part be explained by the impact of non-native speakers on information encoding strategies. Finally, we argue that languages are information encoding systems shaped by the varying needs of their speakers. Language evolution and change should be modeled as the co-evolution of multiple intertwined adaptive systems: On one hand, the structure of human societies and human learning capabilities, and on the other, the structure of language. PMID:26083380

An in silico platform for the design of heterologous pathways in nonnative metabolite production

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Chatsurachai Sunisa

2012-05-01

Full Text Available Abstract Background Microorganisms are used as cell factories to produce valuable compounds in pharmaceuticals, biofuels, and other industrial processes. Incorporating heterologous metabolic pathways into well-characterized hosts is a major strategy for obtaining these target metabolites and improving productivity. However, selecting appropriate heterologous metabolic pathways for a host microorganism remains difficult owing to the complexity of metabolic networks. Hence, metabolic network design could benefit greatly from the availability of an in silico platform for heterologous pathway searching. Results We developed an algorithm for finding feasible heterologous pathways by which nonnative target metabolites are produced by host microorganisms, using Escherichia coli, Corynebacterium glutamicum, and Saccharomyces cerevisiae as templates. Using this algorithm, we screened heterologous pathways for the production of all possible nonnative target metabolites contained within databases. We then assessed the feasibility of the target productions using flux balance analysis, by which we could identify target metabolites associated with maximum cellular growth rate. Conclusions This in silico platform, designed for targeted searching of heterologous metabolic reactions, provides essential information for cell factory improvement.

The Effect of Background Noise on the Word Activation Process in Nonnative Spoken-Word Recognition

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Scharenborg, Odette; Coumans, Juul M. J.; van Hout, Roeland

2018-01-01

This article investigates 2 questions: (1) does the presence of background noise lead to a differential increase in the number of simultaneously activated candidate words in native and nonnative listening? And (2) do individual differences in listeners' cognitive and linguistic abilities explain the differential effect of background noise on…

The right to health of non-nationals and displaced persons in the sustainable development goals era: challenges for equity in universal health care.

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Brolan, Claire E; Forman, Lisa; Dagron, Stéphanie; Hammonds, Rachel; Waris, Attiya; Latif, Lyla; Ruano, Ana Lorena

2017-02-21

Under the Millennium Development Goals (MDGs), United Nations (UN) Member States reported progress on the targets toward their general citizenry. This focus repeatedly excluded marginalized ethnic and linguistic minorities, including people of refugee backgrounds and other vulnerable non-nationals that resided within a States' borders. The Sustainable Development Goals (SDGs) aim to be truly transformative by being made operational in all countries, and applied to all, nationals and non-nationals alike. Global migration and its diffuse impact has intensified due to escalating conflicts and the growing violence in war-torn Syria, as well as in many countries in Africa and in Central America. This massive migration and the thousands of refugees crossing borders in search for safety led to the creation of two-tiered, ad hoc, refugee health care systems that have added to the sidelining of non-nationals in MDG-reporting frameworks. We have identified four ways to promote the protection of vulnerable non-nationals' health and well being in States' application of the post-2015 SDG framework: In setting their own post-2015 indicators the UN Member States should explicitly identify vulnerable migrants, refugees, displaced persons and other marginalized groups in the content of such indicators. Our second recommendation is that statisticians from different agencies, including the World Health Organization's Gender, Equity and Human Rights programme should be actively involved in the formulation of SDG indicators at both the global and country level. In addition, communities, civil society and health justice advocates should also vigorously engage in country's formulation of post-2015 indicators. Finally, we advocate that the inclusion of non-nationals be anchored in the international human right to health, which in turn requires appropriate financing allocations as well as robust monitoring and evaluation processes that can hold technocratic decision-makers accountable for

Photodynamic damage of glial cells in crayfish ventral nerve cord

Science.gov (United States)

Kolosov, M. S.; Duz, E.; Uzdensky, A. B.

2011-03-01

Photodynamic therapy (PDT) is a promising method for treatment of brain tumors, the most of which are of glial origin. In the present work we studied PDT-mediated injury of glial cells in nerve tissue, specifically, in abdominal connectives in the crayfish ventral nerve cord. The preparation was photosensitized with alumophthalocyanine Photosens and irradiated 30 min with the diode laser (670 nm, 0.1 or 0.15 W/cm2). After following incubation in the darkness during 1- 10 hours it was fluorochromed with Hoechst 33342 and propidium iodide to reveal nuclei of living, necrotic and apoptotic cells. The chain-like location of the glial nuclei allowed visualization of those enveloping giant axons and blood vessels. The level of glial necrosis in control preparations was about 2-5 %. Apoptosis was not observed in control preparations. PDT significantly increased necrosis of glial cells to 52 or 67 % just after irradiation with 0.1 or 0.15 W/cm2, respectively. Apoptosis of glial cells was observed only at 10 hours after light exposure. Upper layers of the glial envelope of the connectives were injured stronger comparing to deep ones: the level of glial necrosis decreased from 100 to 30 % upon moving from the connective surface to the plane of the giant axon inside the connective. Survival of glial cells was also high in the vicinity of blood vessels. One can suggest that giant axons and blood vessels protect neighboring glial cells from photodynamic damage. The mechanism of such protective action remains to be elucidated.

The effect of sodium ions on the light-induced 86Rb release from the isolated crayfish retina

International Nuclear Information System (INIS)

Hartung, K.; Stieve, H.

1980-01-01

The effect of low external Na + concentrations on the light-induced K + release from crayfish photoreceptor cells was tested by labelling intracellular K + with the isotope 86 Rb. The amount of isotope released per light, stimulus is roughly proportional to the external Na + concentration if the osmolarity is kept constant by replacing Na + with Tris, choline or sucrose. When sucrose is used to replace the depleted Na + the light-induced K + release is a linear function of the external Na + concentration and is reduced by approx. 95% at an external Na + concentration of 5 mmol/l. For choline and Tris substitutions the relationships are less clear but at Na + concentrations + release is smaller in a Tris solution and larger in a choline solution. It is suggested that the light-induced K + release is due mainly to an activation of voltage sensitive K + channels. (orig.)

GLUTATHIONE AND ANTIOXIDANT ENZYMES IN THE HEPATOPANCREAS OF CRAYFISH PROCAMBARUS CLARKII (GIRARD, 1852 OF LAKE TRASIMENO (ITALY

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ELIA A. C.

2006-01-01

Full Text Available Antioxidant parameters, such as total glutathione, glutathione S-transferase, glutathione peroxidase, glutathione reductase, glyoxalases, catalase, and some heavy metals such as, lead, cadmium and chromium were examined in hepatopancreas of both sexes of Procambarus clarkii collected seasonally from Lake Trasimeno, from winter 2002-2003 to autumn 2003. Heavy metals content in hepatopancreas in males and females of P. clarkii was low and did not vary through the sampling periods and between sexes. On the contrary, crayfish exhibited sex-dependent differences in levels of some enzyme activities and of total glutathione, and no apparent relationship was found between contaminant burdens and antioxidant indexes in hepatopancreas. Because measured metal concentrations were low, other factors, presumably, were involved in antioxidant variations in P. clarkii and these latter seemed to be affected more by biological and environmental factors, other than those related to pollutants body burdens.

Positive feedback loop between introductions of non-native marine species and cultivation of oysters in Europe.

Science.gov (United States)

Mineur, Frederic; Le Roux, Auguste; Maggs, Christine A; Verlaque, Marc

2014-12-01

With globalization, agriculture and aquaculture activities are increasingly affected by diseases that are spread through movement of crops and stock. Such movements are also associated with the introduction of non-native species via hitchhiking individual organisms. The oyster industry, one of the most important forms of marine aquaculture, embodies these issues. In Europe disease outbreaks affecting cultivated populations of the naturalized oyster Crassostrea gigas caused a major disruption of production in the late 1960s and early 1970s. Mitigation procedures involved massive imports of stock from the species' native range in the northwestern Pacific from 1971 to 1977. We assessed the role stock imports played in the introduction of non-native marine species (including pathogens) from the northwestern Pacific to Europe through a methodological and critical appraisal of record data. The discovery rate of non-native species (a proxy for the introduction rate) from 1966 to 2012 suggests a continuous vector activity over the entire period. Disease outbreaks that have been affecting oyster production since 2008 may be a result of imports from the northwestern Pacific, and such imports are again being considered as an answer to the crisis. Although successful as a remedy in the short and medium terms, such translocations may bring new diseases that may trigger yet more imports (self-reinforcing or positive feedback loop) and lead to the introduction of more hitchhikers. Although there is a legal framework to prevent or reduce these introductions, existing procedures should be improved. © 2014 Society for Conservation Biology.

The influence of ungulates on non-native plant invasions in forests and rangelands: a review.

Science.gov (United States)

Catherine G. Parks; Michael J. Wisdom; John G. Kie

2005-01-01

Herbivory by wild and domestic ungulates can strongly influence vegetation composition and productivity in forest and range ecosystems. However, the role of ungulates as contributors to the establishment and spread of non-native invasive plants is not well known. Ungulates spread seeds through endozoochory (passing through an animal's digestive tract) or...

Computer Vision Syndrome for Non-Native Speaking Students: What Are the Problems with Online Reading?

Science.gov (United States)

Tseng, Min-chen

2014-01-01

This study investigated the online reading performances and the level of visual fatigue from the perspectives of non-native speaking students (NNSs). Reading on a computer screen is more visually more demanding than reading printed text. Online reading requires frequent saccadic eye movements and imposes continuous focusing and alignment demand.…

DISCOURSE AWARENESS IN IMPROVING NON-NATIVE STUDENTS’ ABILITY IN GENERIC WRITING

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Hussain AL SHAROUFI

2014-04-01

Full Text Available This study explores the importance of teaching discourse patterns to non-native university students. I used particular discourse patterns in teaching generic writing to undergraduate students at the Gulf University for Science and Technology, GUST, in Kuwait. The assumption of this study was that undergraduate non-native students should be aware of the importance of discourse patterns in generic writing. This hidden tactic is not obvious unless consciously taught to them. To study the importance of generic patterns, I opted to teach discourse patterns that are used in newspaper editorials, the rationale of which was that students would grasp discourse patterns and apply them to their own writing. I chose two groups of students randomly, one of which was an experimental group and the second of which was a control group. I conducted a detailed analysis afterwards to examine the validity of my assumption. I taught the experimental group the chosen model of analysis, and instructed the control group to read sample editorials, and write their own editorials afterwards. The results of this experiment were substantial. Based on the level of compliance with the suggested format, triads, movements, and artifacts in newspaper editorials, students in the experimental group were evaluated on a scale of 0 to 10. The performance of the experimental group was above average, 75.3%, in comparison to the control group that complied quite poorly with the chosen model, < 30 %.

An Exploration of the Scientific Writing Experience of Nonnative English-Speaking Doctoral Supervisors and Students Using a Phenomenographic Approach

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Elizabeth Dean

2015-01-01

Full Text Available Nonnative English-speaking scholars and trainees are increasingly submitting their work to English journals. The study’s aim was to describe their experiences regarding scientific writing in English using a qualitative phenomenographic approach. Two focus groups (5 doctoral supervisors and 13 students were conducted. Participants were nonnative English-speakers in a Swedish health sciences faculty. Group discussion focused on scientific writing in English, specifically, rewards, challenges, facilitators, and barriers. Participants were asked about their needs for related educational supports. Inductive phenomenographic analysis included extraction of referential (phenomenon as a whole and structural (phenomenon parts aspects of the transcription data. Doctoral supervisors and students viewed English scientific writing as challenging but worthwhile. Both groups viewed mastering English scientific writing as necessary but each struggles with the process differently. Supervisors viewed it as a long-term professional responsibility (generating knowledge, networking, and promotion eligibility. Alternatively, doctoral students viewed its importance in the short term (learning publication skills. Both groups acknowledged they would benefit from personalized feedback on writing style/format, but in distinct ways. Nonnative English-speaking doctoral supervisors and students in Sweden may benefit from on-going writing educational supports. Editors/reviewers need to increase awareness of the challenges of international contributors and maximize the formative constructiveness of their reviews.

Native and non-native plants provide similar refuge to invertebrate prey, but less than artificial plants

NARCIS (Netherlands)

Grutters, Bart; Pollux, B.J.A.; Verberk, W.C.E.P.; Bakker, E.S.

2015-01-01

Non-native species introductions are widespread and can affect ecosystem functioning by altering the structure of food webs. Invading plants often modify habitat structure, which may affect the suitability of vegetation as refuge and could thus impact predator-prey dynamics. Yet little is known

Similarity of 241Am and 59Fe speciation in selected freshwaters and of their adsorption on crayfish exoskeleton

International Nuclear Information System (INIS)

Vangenechten, J.H.D.; Chughtai, N.A.; Bierkens, J.; Vanderborght, O.L.J.

1987-01-01

The particulate fraction and the organically complexed fraction of freshly added 241 Am and 59 Fe were determined in 21 prefiltered surface waters. The adsorptive behaviour of both radionuclides on a biological surface (isolated carapace segments of crayfish) was tested simultaneously. A striking similarity was observed in the chemical and absorptive behaviours of both radionuclides. The stoichiometry of particulate formation revealed a 3/4, Am to Fe ratio. This same stoichiometric relationship was observed in organic complexation, while adsorptive behaviour was characterised by a 1/1, Am to Fe ratio. It is concluded that Am predictably follows the chemistry of freshly added Fe at least over a 15 day period. This observation may find interesting application in risk assessment where use can be made of the well-known geochemical cycling of iron to predict the behaviour of man-made Am. (author)

What vaccination studies tell us about immunological memory within the innate immune system of cultured shrimp and crayfish.

Science.gov (United States)

Chang, Yu-Hsuan; Kumar, Ramya; Ng, Tze Hann; Wang, Han-Ching

2018-03-01

The possibility of immunological memory in invertebrates is a topic that has recently attracted a lot of attention. Today, even vertebrates are known to exhibit innate immune responses that show memory-like properties, and since these responses are triggered by cells that are involved in the innate immune system, it seems that immune specificity and immune memory do not necessarily require the presence of B cells and T cells after all. This kind of immune response has been called "immune priming" or "trained immunity". In this report, we review recent observations and our current understanding of immunological memory within the innate immune system in cultured shrimp and crayfish after vaccination with live vaccine, killed vaccine and subunit vaccines. We also discuss the possible mechanisms involved in this immune response. Copyright © 2017 Elsevier Ltd. All rights reserved.

Expansion of Non-Native Brown Trout in South Europe May Be Inadvertently Driven by Stocking: Molecular and Social Survey in the North Iberian Narcea River.

Science.gov (United States)

Horreo, Jose L; Abad, David; Dopico, Eduardo; Oberlin, Maud; Garcia-Vazquez, Eva

2015-07-09

The biological and anthropogenic (management) factors that may contribute to the expansion of non-native lineages in managed fish have been studied in this work taking brown trout (Salmo trutta) as a model species. The changes of users' opinion about stocking was studied employing social science methodology (surveys). The evolution of hatchery stocks together with the outcome of stocking were analysed with two genetic tools: the LDH-C1* locus (marker of non-native stocks) and six microsatellite loci (for assignment of wild trout to the natural population or putative hatchery stocks). Consulted stakeholders were convinced of the correctness of releasing only native stocks, although in practice the hatcheries managed by them contained important proportions of non-native gene carriers. Our results suggest that allochthonous individuals perform better and grow faster in hatchery conditions than the native ones. We also find a dilution of the impact of this kind of suplementation in wild conditions. The use of only native individuals as hatchery breeders tested for the presence of non-native alleles previously to the artificial crosses must be a priority. Surveys can help steer policy making toward decisions that will be followed by the public, but they should not be used to justify science.

Expansion of Non-Native Brown Trout in South Europe May Be Inadvertently Driven by Stocking: Molecular and Social Survey in the North Iberian Narcea River

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Jose L. Horreo

2015-07-01

Full Text Available The biological and anthropogenic (management factors that may contribute to the expansion of non-native lineages in managed fish have been studied in this work taking brown trout (Salmo trutta as a model species. The changes of users’ opinion about stocking was studied employing social science methodology (surveys. The evolution of hatchery stocks together with the outcome of stocking were analysed with two genetic tools: the LDH-C1* locus (marker of non-native stocks and six microsatellite loci (for assignment of wild trout to the natural population or putative hatchery stocks. Consulted stakeholders were convinced of the correctness of releasing only native stocks, although in practice the hatcheries managed by them contained important proportions of non-native gene carriers. Our results suggest that allochthonous individuals perform better and grow faster in hatchery conditions than the native ones. We also find a dilution of the impact of this kind of suplementation in wild conditions. The use of only native individuals as hatchery breeders tested for the presence of non-native alleles previously to the artificial crosses must be a priority. Surveys can help steer policy making toward decisions that will be followed by the public, but they should not be used to justify science.

Nitric oxide-mediated intersegmental modulation of cycle frequency in the crayfish swimmeret system.

Science.gov (United States)

Yoshida, Misaki; Nagayama, Toshiki; Newland, Philip

2018-05-21

Crayfish swimmerets are paired appendages located on the ventral side of each abdominal segment that show rhythmic beating during forward swimming produced by central pattern generators in most abdominal segments. For animals with multiple body segments and limbs, intersegmental coordination of central pattern generators in each segment is crucial for the production of effective movements. Here we develop a novel pharmacological approach to analyse intersegmental modulation of swimmeret rhythm by selectively elevating nitric oxide levels and reducing them with pharmacological agents, in specific ganglia. Bath application of L-arginine, the substrate NO synthesis, increased the cyclical spike responses of the power-stroke motor neurons. By contrast the NOS inhibitor, L-NAME decreased them. To determine the role of the different local centres in producing and controlling the swimmeret rhythm, these two drugs were applied locally to two separate ganglia following bath application of carbachol. Results revealed that there was both ascending and descending intersegmental modulation of cycle frequency of the swimmeret rhythm in the abdominal ganglia and that synchrony of cyclical activity between segments of segments was maintained. We also found that there were gradients in the strength effectiveness in modulation, that ascending modulation of the swimmeret rhythm was stronger than descending modulation. © 2018. Published by The Company of Biologists Ltd.

Non-native english speaking elementary ell teachers’ culturally responsive leadership profile in an ESL context

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Valentin Ekiaka Nzai

2012-12-01

Full Text Available Culturally responsive instruction has been suggested as quality education (Edwards, 2003 for minority students in subtractive and additivebilingualism settings. However, analytical curriculum development of several official English programs revealed that the gender-centric (malecentricand Ethno-centric (Euro/Western-centric approaches were deeply embedded in most English textbooks of curriculum development.The intent of partial mixed methods paper consisted of exploring some non-native English speaking teachers English teachers’ culturallyresponsive leadership profile in order to further the discussion on not only how to promote English curriculum transformation in English assecond language (ESL and English as foreign language (EFL settings, but also to effectively train culturally responsive non-native Englishspeaking (NNES English pre-service teachers. Comparative data analysis suggested that there were no causal relationship between NNESEnglish teachers’ culturally responsive leadership styles and their abilities to perform multicultural transformation of English curriculums. To behighly effective in transforming English curriculum, NNES English teachers needed to be systematically trained on how to do so. Implicationsfor NNES English pre-service teacher education are framed from the culturally responsive and anti-oppressive education approaches.

Modification of sodium and potassium channel kinetics by diethyl ether and studies on sodium channel inactivation in the crayfish giant axon membrane

Energy Technology Data Exchange (ETDEWEB)

Bean, Bruce Palmer [Univ. of Rochester, NY (United States)

1979-01-01

The effects of ether and halothane on membrane currents in the voltage clamped crayfish giant axon membrane were investigated. Concentrations of ether up to 300 mM and of halothane up to 32 mM had no effect on resting potential or leakage conductance. Ether and halothane reduced the size of sodium currents without changing the voltage dependence of the peak currents or their reversal potential. Ether and halothane also produced a reversible, dose-dependent speeding of sodium current decay at all membrane potentials. Ether reduced the time constants for inactivation, and also shifted the midpoint of the steady-state inactivation curve in the hyperpolarizing direction. Potassium currents were smaller with ether present, with no change in the voltage dependence of steady-state currents. The activation of potassium channels was faster with ether present. There was no apparent change in the capacitance of the crayfish giant axon membrane with ether concentrations of up to 100 mM. Experiments on sodium channel inactivation kinetics were performed using 4-aminopyridine to block potassium currents. Sodium currents decayed with a time course generally fit well by a single exponential. The time constant of decay was a steep function of voltage, especially in the negative resistance region of the peak current vs voltage relation.The time course of inactivation was very similar to that of the decay of the current at the same potential. The measurement of steady-state inactivation curves with different test pulses showed no shifts along the voltage asix. The voltage-dependence of the integral of sodium conductance was measured to test models of sodium channel inactivation in which channels must open before inactivating; the results appear inconsistent with some of the simplest cases of such models.

The relationship between brain reaction and English reading tests for non-native English speakers.

Science.gov (United States)

Cheng, Pei-Wen; Tian, Yu-Jie; Kuo, Ting-Hua; Sun, Koun-Tem

2016-07-01

This research analyzed the brain activity of non-native English speakers while engaged in English reading tests. The brain wave event-related potentials (ERPs) of participants were used to analyze the difference between making correct and incorrect choices on English reading test items. Three English reading tests of differing levels were designed and 20 participants, 10 males and 10 females whose ages ranged from 20 to 24, voluntarily participated in the experiment. Experimental results were analyzed by performing independent t-tests on the ERPs of participants for gender, difficulty level, and correct versus wrong options. Participants who chose incorrect options elicited a larger N600, verifying results found in the literature. Another interesting result was found: For incorrectly answered items, different areas of brain showing a significant difference in ERPs between the chosen and non-chosen options corresponded to gender differences; for males, this area was located in the right hemisphere whereas for females, it was located in the left. Experimental results imply that non-native English speaking males and females employ different areas of the brain to comprehend the meaning of difficult items. Copyright © 2016 Elsevier B.V. All rights reserved.

Global compositional variation among native and non-native regional insect assemblages emphasizes the importance of pathways

Science.gov (United States)

Andrew M. Liebhold; Takehiko Yamanaka; Alain Roques; Sylvie Augustin; Steven L. Chown; Eckehard G. Brockerhoff; Petr Pysek

2016-01-01

Insects are among the world's most ecologically and economically important invasive species. Here we assemble inventories of native and nonnative species from 20 world regions and contrast relative numbers among these species assemblages. Multivariate ordination indicates that the distribution of species among insect orders is completely different between native...

Socio-economic drivers of specialist anglers targeting the non-native European catfish (Silurus glanis in the UK.

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E M Ann Rees

Full Text Available Information about the socioeconomic drivers of Silurus glanis anglers in the UK were collected using questionnaires from a cross section of mixed cyprinid fisheries to elucidate human dimensions in angling and non-native fisheries management. Respondents were predominantly male (95%, 30-40 years of age with £500 per annum. The proportion of time spent angling for S. glanis was significantly related to angler motivations; fish size, challenge in catch, tranquil natural surroundings, escape from daily stress and to be alone were considered important drivers of increased time spent angling. Overall, poor awareness of: the risks and adverse ecological impacts associated with introduced S. glanis, non-native fisheries legislation, problems in use of unlimited ground bait and high fish stocking rates in angling lakes were evident, possibly related to inadequate training and information provided by angling organisations to anglers, as many stated that they were insufficiently informed.

When the Native Is Also a Non-Native: "Retrodicting" the Complexity of Language Teacher Cognition

Science.gov (United States)

Aslan, Erhan

2015-01-01

The impact of native (NS) and non-native speaker (NNS) identities on second or foreign language teachers' cognition and practices in the classroom has mainly been investigated in ESL/EFL contexts. Using complexity theory as a framework, this case study attempts to fill the gap in the literature by presenting a foreign language teacher in the…

The comparative analysis of English and Lithuanian transport terms and some methods of developing effective science writing strategies by non-native speakers of English

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V. Marina

2009-09-01

Full Text Available The paper addresses the problem of developing more effective strategies and skills of writing scientific and technical texts by non-native speakers of English. The causes of poor writing are identified and general guidelines for developing effective science writing strategies are outlined. The analysis of difficulties faced by non-native speakers of English in writing research papers is made by examining transport terms and international words which are based on different nomination principles in English and Lithuanian. Case study of various names given to a small vehicle used for passenger transportation in many countries is provided, illustrating the alternative ways of naming the same object of reality in different languages. The analysis is based on the theory of linguistic relativity. Differences in the use of similar international terms in English and Lithuanian, which often cause errors and misunderstanding, are also demonstrated. The recommendations helping non-native speakers of English to avoid errors and improve skills of writing scientific and technical texts are given.

Prevention, early detection and containment of invasive, nonnative plants in the Hawaiian Islands: current efforts and needs

Science.gov (United States)

Christoph Kueffer,; Loope, Lloyd

2009-01-01

Introduction: Invasive, non-native plants (or environmental weeds) have long been recognized as a major threat to the native biodiversity of oceanic islands (Cronk & Fuller, 1995; Denslow, 2003). Globally, several hundred non-native plant species have been reported to have major impacts on natural areas on oceanic islands (Kueffer et al., 2009). In Hawaii, at least some 50 non-native plant species reach dominance in natural areas (Kueffer et al., 2009) and many of them are known to impact ecosystem processes or biodiversity. One example is the invasive Australian tree fern (Cyathea cooperi), which has been shown to be very efficient at utilizing soil nitrogen and can grow six times as rapidly in height, maintain four times more fronds, and produce significantly more fertile fronds per month than the native Hawaiian endemic tree ferns, Cibotium spp. (Durand & Goldstein, 2001a, b). Additionally, while native tree ferns provide an ideal substrate for epiphytic growth of many understory ferns and flowering plants, the Australian tree fern has the effect of impoverishing the understory and failing to support an abundance of native epiphytes (Medeiros & Loope, 1993). Other notorious examples of invasive plant species problematic for biodiversity and ecosystem processes in Hawaii include miconia (Miconia calvescens), strawberry guava (Psidium cattleianum), albizia (Falcataria moluccana), firetree (Morella faya), clidemia (Clidemia hirta), kahili ginger (Hedychium gardnerianum), and fountain grass (Pennisetum setaceum), to name just a few. Fireweed (Senecio madagascariensis) is a recent example of a seriously problematic invasive species for Hawaii’s agriculture and is damaging certain high-elevations native ecosystems as well.

A Computer Text Analysis of Four Cohesion Devices in English Discourse by Native and Nonnative Writers.

Science.gov (United States)

Reid, Joy

1992-01-01

In a contrastive rhetoric study of nonnative English speakers, 768 essays written in English by native speakers of Arabic, Chinese, Spanish, and English were examined using the Writer's Workbench program to determine whether distinctive, quantifiable differences in the use of 4 cohesion devices existed among the 4 language backgrounds. (Author/LB)

PcToll3 was involved in anti-Vibrio response by regulating the expression of antimicrobial peptides in red swamp crayfish, Procambarus clarkii.

Science.gov (United States)

Lan, Jiang-Feng; Wei, Shun; Wang, Yu-Qing; Dai, Yun-Jia; Tu, Jia-Gang; Zhao, Li-Juan; Li, Xin-Cang; Qin, Qi-Wei; Chen, Nan; Lin, Li

2016-10-01

Tolls and Toll-like receptors (TLRs) play an important role in host immune defenses by regulating the expression of antimicrobial peptides (AMPs) and cytokines, but the functional differences of crustacean Tolls from Drosophila Tolls or Mammal TLRs are largely unknown. A novel Toll receptor, named PcToll3, was identified from red swamp crayfish, Procambarus clarkii. It was widely expressed in all detected tissues, and its transcript in hemocytes was up-regulated at 12 h after Vibrio parahemolyticus (Vibrio) injection or at 24 h post white spot syndrome virus (WSSV) challenge. After knockdown of PcToll3, the activity of bacterial clearance was inhibited, and the expression levels of AMPs including Crustin1 (Cru1), Anti-lippopolysaccharide factor 1 (ALF1), and Lysozymes1 (Lys1), which could be up-regulated by Vibrio, were all affected. Meanwhile, PcToll3 silencing influenced the expression of myeloid differentiation factor 88 (PcMyd88), tumor necrosis factor-associated factor 6 (PcTRAF6), and PcDorsal, which were the counterparts of Drosophila Toll signaling pathway. Interestingly, PcToll3 silencing inhibited translocation of PcDorsal from cytoplasm to nucleus. Furthermore, the knockdown of PcDorsal also impaired the expression of AMPs after Vibrio challenge. Hence, we concluded that, besides participating in antiviral immunity, PcToll3 might also regulate the expression of Cru1 and Lys1 to participate in anti-Vibrio immune responses by promoting PcDorsal translocation into nucleus. Copyright © 2016 Elsevier Ltd. All rights reserved.

Salinity tolerance of non-native suckermouth armoured catfish (Loricariidae: Pterygoplichthys) in south-eastern Mexico: implications for invasion and dispersal

Science.gov (United States)

Capps, Krista A.; Nico, Leo G.; Mendoza-Carranza, Manuel; Arevalo-Frias, Wendi; Ropicki, Andrew J.; Heilpern, Sebastian A.; Rodiles-Hernandez, Rocio

2011-01-01

1. Salinity tolerance is one of several important physiological attributes that determine invasion success and the pattern of dispersal of introduced aquatic organisms. Introduced freshwater fishes able to tolerate elevated salinities have the potential to invade and exploit brackish-water (mixohaline) environments and use estuaries and coastal waters as 'bridges' for dispersing from one coastal river system to another. 2. Several members of the neotropical suckermouth armoured catfish genus Pterygoplichthys (Siluriformes: Loricariidae) have established non-native populations in inland waters of North and Central America, Asia and islands in the Caribbean, and Pacific and Indian oceans. Loricariids are generally considered to be strictly freshwater; but a few naturally occur in mesohaline habitats. 3.Catch and habitat data from 2004–2005 and 2009–2011 fish surveys in the Grijalva–Usumacinta River delta region (south-eastern Mexico) confirmed that introduced Pterygoplichthys populations established in upstream freshwater sites (where these catfish are abundant) have recently dispersed into downstream oligohaline and mesohaline estuarine habitats. During 2009–2011 surveys, these non-native catfish — tentatively identified as P. pardalis or its hybrids — were found in sites with salinities ranging from 1 to 8 ppt (mean 5.2 ppt). 4.Acute-salinity experiments were conducted with Pterygoplichthys (110–302 mm standard length, N=140) captured in the Grijalva–Usumacinta Basin to determine upper salinity tolerance levels. Tests demonstrated that individuals maintained in salinities of 0.2 ppt were able to survive abrupt (acute) exposure to salinities up to 10 ppt with little mortality over 10 days (240 h experimental endpoint). A few individuals survived abrupt exposure to 11 and 12 ppt for 20 or more hours, although none survived more than a few hours at 16 ppt or greater. 5.These field and experimental results provide quantitative evidence that non-native

Teaching Effectiveness of Non-Native English-Speaking Teachers in Business Disciplines: Intercultural Communication Apprehension and Ethnocentrism

Science.gov (United States)

Abayadeera, Nadana; Mihret, Dessalegn Getie; Hewa Dulige, Jayasinghe

2018-01-01

Teaching effectiveness of non-native English-speaking teachers (NNEST) in accounting, economics and finance has become a significant issue due to the increasing trend of hiring NNEST in business schools. However, the literature has focused on the English language competence of NNEST, which is only one element of the factors that influence teaching…

Invasion by nonnative brook trout in Panther Creek, Idaho: Roles of habitat quality, connectivity, and biotic resistance

Science.gov (United States)

Joseph R. Benjamin

2006-01-01

Theoretical models suggest the invasion of nonnative freshwater species is facilitated through the interaction of three factors: biotic resistance, habitat quality, and connectivity. We measured variables that represented each component to determine which were associated with small (150 mm) brook trout occurrence in Panther Creek, a tributary...

Differences in Competitive Ability between Plants from Nonnative and Native Populations of a Tropical Invader Relates to Adaptive Responses in Abiotic and Biotic Environments

Science.gov (United States)

Liao, Zhi-Yong; Zhang, Ru; Barclay, Gregor F.; Feng, Yu-Long

2013-01-01

The evolution of competitive ability of invasive plant species is generally studied in the context of adaptive responses to novel biotic environments (enemy release) in introduced ranges. However, invasive plants may also respond to novel abiotic environments. Here we studied differences in competitive ability between Chromolaena odorata plants of populations from nonnative versus native ranges, considering biogeographical differences in both biotic and abiotic environments. An intraspecific competition experiment was conducted at two nutrient levels in a common garden. In both low and high nutrient treatments, C. odorata plants from nonnative ranges showed consistently lower root to shoot ratios than did plants from native ranges grown in both monoculture and competition. In the low nutrient treatment, C. odorata plants from nonnative ranges showed significantly lower competitive ability (competition-driven decreases in plant height and biomass were more), which was associated with their lower root to shoot ratios and higher total leaf phenolic content (defense trait). In the high nutrient treatment, C. odorata plants from nonnative ranges showed lower leaf toughness and cellulosic contents (defense traits) but similar competitive ability compared with plants from native ranges, which was also associated with their lower root to shoot ratios. Our results indicate that genetically based shifts in biomass allocation (responses to abiotic environments) also influence competitive abilities of invasive plants, and provide a first potential mechanism for the interaction between range and environment (environment-dependent difference between ranges). PMID:23977140

High water-use efficiency and growth contribute to success of non-native Erodium cicutarium in a Sonoran Desert winter annual community.

Science.gov (United States)

Kimball, Sarah; Gremer, Jennifer R; Barron-Gafford, Greg A; Angert, Amy L; Huxman, Travis E; Venable, D Lawrence

2014-01-01

The success of non-native, invasive species may be due to release from natural enemies, superior competitive abilities, or both. In the Sonoran Desert, Erodium cicutarium has increased in abundance over the last 30 years. While native species in this flora exhibit a strong among-species trade-off between relative growth rate and water-use efficiency, E. cicutarium seems to have a higher relative growth rate for its water-use efficiency value relative to the pattern across native species. This novel trait combination could provide the non-native species with a competitive advantage in this water-limited environment. To test the hypothesis that E. cicutarium is able to achieve high growth rates due to release from native herbivores, we compared the effects of herbivory on E. cicutarium and its native congener, Erodium texanum. We also compared these two species across a range of environmental conditions, both in a common garden and in two distinct seasons in the field, using growth analysis, isotopic compositions and leaf-level gas exchange. Additionally, we compared the competitive abilities of the two Erodium species in a greenhouse experiment. We found no evidence of herbivory to either species. Physiological measurements in a common environment revealed that E. cicutarium was able to achieve high growth rates while simultaneously controlling leaf-level water loss. Non-native E. cicutarium responded to favourable conditions in the field with greater specific leaf area and leaf area ratio than native E. texanum. The non-native Erodium was a stronger competitor than its native congener in a greenhouse competition experiment. The ability to maintain relatively higher values of water-use efficiency:relative growth rate in comparison to the native flora may be what enables E. cictarium to outcompete native species in both wet and dry years, resulting in an increase in abundance in the highly variable Sonoran Desert.

Regulation of G-protein coupled receptor traffic by an evolutionary conserved hydrophobic signal.

Science.gov (United States)

Angelotti, Tim; Daunt, David; Shcherbakova, Olga G; Kobilka, Brian; Hurt, Carl M

2010-04-01

Plasma membrane (PM) expression of G-protein coupled receptors (GPCRs) is required for activation by extracellular ligands; however, mechanisms that regulate PM expression of GPCRs are poorly understood. For some GPCRs, such as alpha2c-adrenergic receptors (alpha(2c)-ARs), heterologous expression in non-native cells results in limited PM expression and extensive endoplasmic reticulum (ER) retention. Recently, ER export/retentions signals have been proposed to regulate cellular trafficking of several GPCRs. By utilizing a chimeric alpha(2a)/alpha(2c)-AR strategy, we identified an evolutionary conserved hydrophobic sequence (ALAAALAAAAA) in the extracellular amino terminal region that is responsible in part for alpha(2c)-AR subtype-specific trafficking. To our knowledge, this is the first luminal ER retention signal reported for a GPCR. Removal or disruption of the ER retention signal dramatically increased PM expression and decreased ER retention. Conversely, transplantation of this hydrophobic sequence into alpha(2a)-ARs reduced their PM expression and increased ER retention. This evolutionary conserved hydrophobic trafficking signal within alpha(2c)-ARs serves as a regulator of GPCR trafficking.

Non-Native Japanese Listeners' Perception of Vowel Length Contrasts in Japanese and Modern Standard Arabic (MSA)

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Tsukada, Kimiko

2012-01-01

This study aimed to compare the perception of short vs. long vowel contrasts in Japanese and Modern Standard Arabic (MSA) by four groups of listeners differing in their linguistic backgrounds: native Arabic (NA), native Japanese (NJ), non-native Japanese (NNJ) and Australian English (OZ) speakers. The NNJ and OZ groups shared the first language…

Susceptibility of burned black spruce (Picea mariana) forests to non-native plant invasions in interior Alaska

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Katie V. Spellman; Christa P.H. Mulder; Teresa N. Hollingsworth

2014-01-01

As climate rapidly warms at high-latitudes, the boreal forest faces the simultaneous threats of increasing invasive plant abundances and increasing area burned by wildfire. Highly flammable and widespread black spruce (Picea mariana) forest represents a boreal habitat that may be increasingly susceptible to non-native plant invasion. This study assess the role of burn...

Interactive influences of wildfire and nonnative species on plant community succession in Hawaii Volcanoes National Park.

Science.gov (United States)

Alison Ainsworth

2007-01-01

The role of fire as a natural disturbance, its interactions with nonnative species and effects of repeated fires in the Hawaiian Islands have received little investigation. We are unsure of the role fire played in shaping forest structure and composition as well as affecting evolutionary processes of the native biota. Yet, many species do have adaptations that...

Toxicity of some ricefield pesticides to the crayfish P. clarkii, under laboratory and field conditions in Lake Albufera (Spain).

Science.gov (United States)

Andreu-Moliner, E S; Almar, M M; Legarra, I; Núñez, A

1986-12-01

Static toxicities in mature crayfish (Procambarus clarkii) were determined, for eight insecticides, two herbicides and one fungicide which were frequently used in rice cultivation at Lake Albufera in Valencia (Spain). Three concentrations of each product were used: a) The concentration that was recommended by the dealer (in mg/L of active ingredient): Carbofuran 0.40, Carbaryl 0.80, Malathion 0.80, Trichlorfon 0.40, Endosulfan 0.56, Lindane 0.56, Fenitrothion 0.40, Cyfloxylate 0.02, Molinate-Thiobencarb 1.50, Copper Sulfate 0.42, b) Half of the recommended concentration. c) Double of the recommended concentration. In all three of the concentrations tested, only Fenitrothion and Cyfloxylate caused a considerable mortality. The other ones do not actually produce any important effects on P. clarkii in our conditions. Nevertheless, insecticides are more toxic than herbicides or fungicides, as the latter show a rather low toxicity.

Similarity of /sup 241/Am and /sup 59/Fe speciation in selected freshwaters and of their adsorption on crayfish exoskeleton

Energy Technology Data Exchange (ETDEWEB)

Vangenechten, J.H.D.; Chughtai, N.A.; Bierkens, J.; Vanderborght, O.L.J.

1987-01-01

The particulate fraction and the organically complexed fraction of freshly added /sup 241/Am and /sup 59/Fe were determined in 21 prefiltered surface waters. The adsorptive behaviour of both radionuclides on a biological surface (isolated carapace segments of crayfish) was tested simultaneously. A striking similarity was observed in the chemical and absorptive behaviours of both radionuclides. The stoichiometry of particulate formation revealed a 3/4, Am to Fe ratio. This same stoichiometric relationship was observed in organic complexation, while adsorptive behaviour was characterised by a 1/1, Am to Fe ratio. It is concluded that Am predictably follows the chemistry of freshly added Fe at least over a 15 day period. This observation may find interesting application in risk assessment where use can be made of the well-known geochemical cycling of iron to predict the behaviour of man-made Am.

The roles of climate, phylogenetic relatedness, introduction effort, and reproductive traits in the establishment of non-native reptiles and amphibians.

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van Wilgen, Nicola J; Richardson, David M

2012-04-01

We developed a method to predict the potential of non-native reptiles and amphibians (herpetofauna) to establish populations. This method may inform efforts to prevent the introduction of invasive non-native species. We used boosted regression trees to determine whether nine variables influence establishment success of introduced herpetofauna in California and Florida. We used an independent data set to assess model performance. Propagule pressure was the variable most strongly associated with establishment success. Species with short juvenile periods and species with phylogenetically more distant relatives in regional biotas were more likely to establish than species that start breeding later and those that have close relatives. Average climate match (the similarity of climate between native and non-native range) and life form were also important. Frogs and lizards were the taxonomic groups most likely to establish, whereas a much lower proportion of snakes and turtles established. We used results from our best model to compile a spreadsheet-based model for easy use and interpretation. Probability scores obtained from the spreadsheet model were strongly correlated with establishment success as were probabilities predicted for independent data by the boosted regression tree model. However, the error rate for predictions made with independent data was much higher than with cross validation using training data. This difference in predictive power does not preclude use of the model to assess the probability of establishment of herpetofauna because (1) the independent data had no information for two variables (meaning the full predictive capacity of the model could not be realized) and (2) the model structure is consistent with the recent literature on the primary determinants of establishment success for herpetofauna. It may still be difficult to predict the establishment probability of poorly studied taxa, but it is clear that non-native species (especially lizards

Riparian Vegetation Response to the March 2008 Short-Duration, High-Flow Experiment-Implications of Timing and Frequency of Flood Disturbance on Nonnative Plant Establishment Along the Colorado River Below Glen Canyon Dam

Science.gov (United States)

Ralston, Barbara E.

2010-01-01

Riparian plant communities exhibit various levels of diversity and richness. These communities are affected by flooding and are vulnerable to colonization by nonnative species. Since 1996, a series of three high-flow experiments (HFE), or water releases designed to mimic natural seasonal flooding, have been conducted at Glen Canyon Dam, Ariz., primarily to determine the effectiveness of using high flows to conserve sediment, a limited resource. These experiments also provide opportunities to examine the susceptibility of riparian plant communities to nonnative species invasions. The third and most recent HFE was conducted from March 5 to 9, 2008, and scientists with the U.S. Geological Survey's Grand Canyon Monitoring and Research Center examined the effects of high flows on riparian vegetation as part of the overall experiment. Total plant species richness, nonnative species richness, percent plant cover, percent organic matter, and total carbon measured from sediment samples were compared for Grand Canyon riparian vegetation zones immediately following the HFE and 6 months later. These comparisons were used to determine if susceptibility to nonnative species establishment varied among riparian vegetation zones and if the timing of the HFE affected nonnative plant establishment success. The 2008 HFE primarily buried vegetation rather than scouring it. Percent nonnative cover did not differ among riparian vegetation zones; however, in the river corridor affected by Glen Canyon Dam operations, nonnative species richness showed significant variation. For example, species richness was significantly greater immediately after and 6 months following the HFE in the hydrologic zone farthest away from the shoreline, the area that represents the oldest riparian zone within the post-dam riparian area. In areas closer to the river channel, tamarisk (Tamarix ramosissima X chinensis) seedling establishment occurred (tamarisk seed production, or in 1986, a year following several

Relationship between Homesickness and Test Anxiety in Non-Native Students of Shiraz University of Medical Sciences International Branch in the Clinical and Physiopathology Course In 2013.

Science.gov (United States)

Azizi, Saman

2015-12-17

Anxiety is an emotional and physiological response to the internal felling of overall danger that is easily resolved. The aim of this study has been to determine the relationship between exam anxiety and the feeling of homesickness among non-native students. The present study is cross-sectional and the subjects in this study are 80 non-native male and female PhD candidates in clinical and physiopathology majors in 2013 academic year that have been evaluated with the help of Persian homesickness questionnaire and Sarason's test anxiety questionnaire and the data was analyzed using Pearson's correlation coefficient. With regard to the Pearson's correlation coefficient there is a significant and reverse relationship between the desire to return to home and exam anxiety (r=0.0344, p=0.004) and there is a significant and reverse relationship between the Compatibility and exam anxiety (r=0.428, panxiety (r=0.888, panxiety and the mental health of non-native students will be deteriorated by the feeling of homesickness and anxiety.

An Investigation into Native and Non-Native Teachers' Judgments of Oral English Performance: A Mixed Methods Approach

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Kim, Youn-Hee

2009-01-01

This study used a mixed methods research approach to examine how native English-speaking (NS) and non-native English-speaking (NNS) teachers assess students' oral English performance. The evaluation behaviors of two groups of teachers (12 Canadian NS teachers and 12 Korean NNS teachers) were compared with regard to internal consistency, severity,…

The interactional establishment of the membership category ‘nonnative speaker’ in gatekeeping encounters

DEFF Research Database (Denmark)

Tranekjær, Louise; Kappa, Katherine

2016-01-01

This paper examines how the membership category ‘nonnative speaker’ is interactionally established and initiated by the ‘native speaker’ interviewers during internship interviews between Danish employers and born abroad1 candidates. The analysis is based on 16 recorded internship interviews...... and related to studies that demonstrate how membership categories are fundamentally indexical of the context of interaction (Day, 2006; Drew & Heritage, 1992; Mondada, 2004). By taking on a membership categorization analysis (MCA) approach and utilizing conversation analytic (CA) tools, this paper shows three...

Nonnative trout impact an alpine-nesting bird by altering aquatic-insect subsidies.

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Epanchin, Peter N; Knapp, Roland A; Lawler, Sharon P

2010-08-01

Adjacent food webs may be linked by cross-boundary subsidies: more-productive donor systems can subsidize consumers in less-productive neighboring recipient systems. Introduced species are known to have direct effects on organisms within invaded communities. However, few studies have addressed the indirect effects of nonnative species in donor systems on organisms in recipient systems. We studied the direct role of introduced trout in altering a lake-derived resource subsidy and their indirect effects in altering a passerine bird's response to that subsidy. We compared the abundance of aquatic insects and foraging Gray-crowned Rosy-Finches (Leucosticte tephrocotis dawsoni, "Rosy-Finch") at fish-containing vs. fishless lakes in the Sierra Nevada Mountains of California (USA). Introduced trout outcompeted Rosy-Finches for emerging aquatic insects (i.e., mayflies). Fish-containing lakes had 98% fewer mayflies than did fishless lakes. In lakes without fish, Rosy-Finches showed an aggregative response to emerging aquatic insects with 5.9 times more Rosy-Finches at fishless lakes than at fish-containing lakes. Therefore, the introduction of nonnative fish into the donor system reduced both the magnitude of the resource subsidy and the strength of cross-boundary trophic interactions. Importantly, the timing of the subsidy occurs when Rosy-Finches feed their young. If Rosy-Finches rely on aquatic-insect subsidies to fledge their young, reductions in the subsidy by introduced trout may have decreased Rosy-Finch abundances from historic levels. We recommend that terrestrial recipients of aquatic subsidies be included in conservation and restoration plans for ecosystems with alpine lakes.

Response of six non-native invasive plant species to wildfires in the northern Rocky Mountains, USA

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Dennis E. Ferguson; Christine L. Craig

2010-01-01

This paper presents early results on the response of six non-native invasive plant species to eight wildfires on six National Forests (NFs) in the northern Rocky Mountains, USA. Stratified random sampling was used to choose 224 stands based on burn severity, habitat type series, slope steepness, stand height, and stand density. Data for this report are from 219 stands...

Projecting invasion risk of non-native watersnakes (Nerodia fasciata and Nerodia sipedon in the western United States.

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Jonathan P Rose

Full Text Available Species distribution models (SDMs are increasingly used to project the potential distribution of introduced species outside their native range. Such studies rarely explicitly evaluate potential conflicts with native species should the range of introduced species expand. Two snake species native to eastern North America, Nerodia fasciata and Nerodia sipedon, have been introduced to California where they represent a new stressor to declining native amphibians, fish, and reptiles. To project the potential distributions of these non-native watersnakes in western North America, we built ensemble SDMs using MaxEnt, Boosted Regression Trees, and Random Forests and habitat and climatic variables. We then compared the overlap between the projected distribution of invasive watersnakes and the distributions of imperiled native amphibians, fish, and reptiles that can serve as prey or competitors for the invaders, to estimate the risk to native species posed by non-native watersnakes. Large areas of western North America were projected to be climatically suitable for both species of Nerodia according to our ensemble SDMs, including much of central California. The potential distributions of both N. fasciata and N. sipedon overlap extensively with the federally threatened Giant Gartersnake, Thamnophis gigas, which inhabits a similar ecological niche. N. fasciata also poses risk to the federally threatened California Tiger Salamander, Ambystoma californiense, whereas N. sipedon poses risk to some amphibians of conservation concern, including the Foothill Yellow-legged Frog, Rana boylii. We conclude that non-native watersnakes in California can likely inhabit ranges of several native species of conservation concern that are expected to suffer as prey or competing species for these invaders. Action should be taken now to eradicate or control these invasions before detrimental impacts on native species are widespread. Our methods can be applied broadly to quantify

Non-native fish introductions and the decline of the mountain yellow-legged frog from within protected areas

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R.A. Knapp; K.R. Matthews

2000-01-01

Abstract: One of the most puzzling aspects of the worldwide decline of amphibians is their disappearance from within protected areas. Because these areas are ostensibly undisturbed, habitat alterations are generally perceived as unlikely causes. The introduction of non-native fishes into protected areas, however, is a common practice throughout the world and may exert...

Preliminary Data on the Ecological Requirements of the Invasive Spiny-Cheek Crayfish in the Lower Danube

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Pîrvu Mălina

2014-12-01

Full Text Available Water quality and properties of the riverbed often shape the community structure of aquatic ecosystems, occasionally sustaining the expansion of non-native species. This study aims to provide preliminary data on the ecological preferences of the invasive species Orconectes limosus, its control, and the protection of the native stock is an European priority. In order to assess the species ability to colonize small river systems, relevant tributaries in the invaded Danube sector were monitored. Statistical test indicates a preference for deep and warm rivers, low water velocity and also high concentrations of calcium.

Loss of biodiversity in a conservation unit of the Brazilian Atlantic Forest: the effect of introducing non-native fish species

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E. N. Fragoso-Moura

Full Text Available Abstract The introduction of species has become an important problem for biodiversity and natural ecosystem conservation. The lake system of the middle Rio Doce (MG, Brazil comprises c. 200 lakes at various conservation states, of which 50 are located within the Rio Doce State Park (PERD. Previous studies had verified several of these lakes suffered non-native fishes introductions and the presence of these species needs for the implementation of actions aiming at not only their control but also the preservation of the native species. This study discusses the effects of non-native fish species in the largest conservation unit of Atlantic Forest in Minas Gerais, southeast of Brazil, using data from 1983 to 2010 distributed as follow: data prior to 2006 were obtained from previous studies, and data from September 2006 to July 2010 were obtained in Lake Carioca at four sampling stations using gillnets, seine nets and sieve. A total of 17 fish species was collected (2006-2010 of which five were introduced species. Among the small to medium size native species (30 to 2000 mm standard length seven had disappeared, two are new records and one was recaptured. The non-native species Cichla kelberi (peacock bass and Pygocentrus nattereri (red piranha are within the most abundant captured species. Integrated with other actions, such as those preventing new introductions, a selective fishing schedule is proposed as an alternative approach to improve the conservation management actions and the local and regional biodiversity maintenance.

Diet of non-native northern snakehead (Channa argus) compared to three co-occurring predators in the lower Potomac River, USA

Science.gov (United States)

Ryan K. Saylor,; Nicolas W.R. Laointe,; Angermeier, Paul

2012-01-01

Introductions of large, non-native, carnivorous fishes continue to occur worldwide and represent a substantial management concern to global biodiversity. One of the most recent non-native fishes to successfully establish in North America is the northern snakehead (Channa argus), found in the lower Potomac River catchment. Dispersal of the northern snakehead throughout this system has been well documented since its original discovery in May 2004; however, little is known about the foraging habits of this species and its interactions with co-occurring predators. Here, we quantify northern snakehead diet in comparison with the diets of naturalised largemouth bass (Micropterus salmoides), and native American eel (Anguilla rostrata) and yellow perch (Perca flavescens) collected from tidal freshwaters bordering Virginia and Maryland near Fort Belvoir, Virginia. Over 97% of northern snakehead gut contents were fishes, with fundulid and centrarchid species consumed most frequently. Dietary overlap was biologically significant only between northern snakehead and largemouth bass. Aquatic invertebrates were >10 times more common in native predator diets, reducing dietary overlap with northern snakehead. Ontogenic shifts in adult northern snakehead diet were also detected, which may be explained by optimal foraging rather than true prey specificity. Northern snakehead may be occupying a novel niche based on a piscivorous diet, therefore limiting competition with resident predators in the lower Potomac River. Further research into interactions between largemouth bass and northern snakehead is needed to inform management decisions and understand the ecological impacts of this non-native species.

Loss of biodiversity in a conservation unit of the Brazilian Atlantic Forest: the effect of introducing non-native fish species.

Science.gov (United States)

Fragoso-Moura, E N; Oporto, L T; Maia-Barbosa, P M; Barbosa, F A R

2016-02-01

The introduction of species has become an important problem for biodiversity and natural ecosystem conservation. The lake system of the middle Rio Doce (MG, Brazil) comprises c. 200 lakes at various conservation states, of which 50 are located within the Rio Doce State Park (PERD). Previous studies had verified several of these lakes suffered non-native fishes introductions and the presence of these species needs for the implementation of actions aiming at not only their control but also the preservation of the native species. This study discusses the effects of non-native fish species in the largest conservation unit of Atlantic Forest in Minas Gerais, southeast of Brazil, using data from 1983 to 2010 distributed as follow: data prior to 2006 were obtained from previous studies, and data from September 2006 to July 2010 were obtained in Lake Carioca at four sampling stations using gillnets, seine nets and sieve. A total of 17 fish species was collected (2006-2010) of which five were introduced species. Among the small to medium size native species (30 to 2000 mm standard length) seven had disappeared, two are new records and one was recaptured. The non-native species Cichla kelberi (peacock bass) and Pygocentrus nattereri (red piranha) are within the most abundant captured species. Integrated with other actions, such as those preventing new introductions, a selective fishing schedule is proposed as an alternative approach to improve the conservation management actions and the local and regional biodiversity maintenance.

Cross-modal Association between Auditory and Visuospatial Information in Mandarin Tone Perception in Noise by Native and Non-native Perceivers

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Beverly Hannah

2017-12-01

Full Text Available Speech perception involves multiple input modalities. Research has indicated that perceivers establish cross-modal associations between auditory and visuospatial events to aid perception. Such intermodal relations can be particularly beneficial for speech development and learning, where infants and non-native perceivers need additional resources to acquire and process new sounds. This study examines how facial articulatory cues and co-speech hand gestures mimicking pitch contours in space affect non-native Mandarin tone perception. Native English as well as Mandarin perceivers identified tones embedded in noise with either congruent or incongruent Auditory-Facial (AF and Auditory-FacialGestural (AFG inputs. Native Mandarin results showed the expected ceiling-level performance in the congruent AF and AFG conditions. In the incongruent conditions, while AF identification was primarily auditory-based, AFG identification was partially based on gestures, demonstrating the use of gestures as valid cues in tone identification. The English perceivers’ performance was poor in the congruent AF condition, but improved significantly in AFG. While the incongruent AF identification showed some reliance on facial information, incongruent AFG identification relied more on gestural than auditory-facial information. These results indicate positive effects of facial and especially gestural input on non-native tone perception, suggesting that cross-modal (visuospatial resources can be recruited to aid auditory perception when phonetic demands are high. The current findings may inform patterns of tone acquisition and development, suggesting how multi-modal speech enhancement principles may be applied to facilitate speech learning.

Salinity tolerance of non-native suckermouth armoured catfish (Loricariidae: Pterygoplichthys sp.) from Kerala, India

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Kumar, A. Biju; Schofield, Pam; Raj, Smrithy; Satheesh, Sima

2018-01-01

Loricariid catfishes of the genus Pterygoplichthys are native to South America and have been introduced in many localities around the world. They are freshwater fishes, but may also use low-salinity habitats such as estuaries for feeding or dispersal. Here we report results of a field survey and salinity-tolerance experiments for a population of Pterygoplichthys sp. collected in Kerala, India. In both chronic and acute salinity-tolerance trials, fish were able to withstand salinities up to 12 ppt with no mortality; however, fish transferred to salinities > 12 ppt did not survive. The experimental results provide evidence that nonnative Pterygoplichthys sp. are able to tolerate mesohaline conditions for extended periods, and can easily invade the brackish water ecosystems of the state. Further, Pterygoplichthys sp. from Kerala have greater salinity tolerance than other congeners. These data are vital to predicting the invasion of non-native fishes such as Pterygoplichthys spp. into coastal systems in Kerala and worldwide. This is particularly important as estuarine ecosystems are under threat of global climate change and sea-level rise. In light of the results of the present study and considering the reports of negative impacts of the species in invaded water bodies, management authorities may consider controlling populations and/or instituting awareness programmes to prevent the spread of this nuisance aquatic invasive species in Kerala.

Comparison of the response (in terms of accumulation, cellular and genetic impacts) of the crayfish Procambarus clarkii after exposure to a metallic pollutant (cadmium) and to a radiological pollutant (uranium 238 and 233)

International Nuclear Information System (INIS)

Al Kaddissi, S.

2012-01-01

The study of the effects of radionuclides and metals on organisms is necessary for the evaluation of their toxicity and their ecological threats. We first aimed to study the impacts of cadmium (Cd) and Uranium (U) on different biological levels of the crayfish Procambarus clarkii after acute and chronic exposures. We evaluated their impacts on mitochondria, oxidative stress responses, on histological structures, and the survival rates. We tried to connect these effects between them and to the bioaccumulation in the gills and the hepato pancreas. We also tried to discriminate the chemo and the radiotoxicity of U by exposing crayfish to either depleted or enriched U ( 233 U: presenting a higher specific activity) using the same criteria of effects. We demonstrated that the gene mt encoding for the metallothionein was always over-expressed in the presence of Cd. Therefore, it seems to be a good bio-marker of Cd toxicity in P. clarkii. The follow up of mitochondrial genes expressions (12s, atp6 and cox1), showed that both metals affect mitochondria and that their mechanisms of action do not seem to be always the same. We also observed that U generates more oxidative stress than Cd when comparing the expression levels of genes encoding for antioxidants (sod (Mn) and mt) and the enzymatic activities of superoxide dismutase, the catalase, the glutathione peroxidase and the glutathione S transferase. However, the symptoms of histo-pathological damages after Cd and U contamination were similar in both conditions. After comparing the survival rates of the crayfish, we concluded that Cd was more toxic than the radioelement. Moreover, we demonstrated that the toxic effect of U on P. clarkii exposed to a low environmental concentration is mainly due to its chemo-toxicity rather than to its radiotoxicity. We established that, the molecular answers vary according to the intensity and the duration of the chemical stress applied to the organisms. We suggested the use of the

Teaching Semantic Radicals Facilitates Inferring New Character Meaning in Sentence Reading for Nonnative Chinese Speakers

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Thi Phuong Nguyen

2017-10-01

Full Text Available This study investigates the effects of teaching semantic radicals in inferring the meanings of unfamiliar characters among nonnative Chinese speakers. A total of 54 undergraduates majoring in Chinese Language from a university in Hanoi, Vietnam, who had 1 year of learning experience in Chinese were assigned to two experimental groups that received instructional intervention, called “old-for-new” semantic radical teaching, through two counterbalanced sets of semantic radicals, with one control group. All of the students completed pre- and post-tests of a sentence cloze task where they were required to choose an appropriate character that fit the sentence context among four options. The four options shared the same phonetic radicals but had different semantic radicals. The results showed that the pre-test and post-test score increases were significant for the experimental groups, but not for the control group. Most importantly, the experimental groups successfully transferred the semantic radical strategy to figure out the meanings of unfamiliar characters containing semantic radicals that had not been taught. The results demonstrate the effectiveness of teaching semantic radicals for lexical inference in sentence reading for nonnative speakers, and highlight the ability of transfer learning to acquire semantic categories of sub-lexical units (semantic radicals in Chinese characters among foreign language learners.

Students Writing Emails to Faculty: An Examination of E-Politeness among Native and Non-Native Speakers of English

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Biesenbach-Lucas, Sigrun

2007-01-01

This study combines interlanguage pragmatics and speech act research with computer-mediated communication and examines how native and non-native speakers of English formulate low- and high-imposition requests to faculty. While some research claims that email, due to absence of non-verbal cues, encourages informal language, other research has…

Competitive effects of non-native plants are lowest in native plant communities that are most vulnerable to invasion

Science.gov (United States)

J.Stephen Brewer; W. Chase Bailey

2014-01-01

Despite widespread acknowledgment that disturbance favors invasion, a hypothesis that has received little attention is whether non-native invaders have greater competitive effects on native plants in undisturbed habitats than in disturbed habitats. This hypothesis derives from the assumption that competitive interactions are more persistent in habitats that have not...

Delexical Structures Contrastively: A Common Trap for Non-Native Speakers

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Marjeta Vrbinc

2004-12-01

Full Text Available This article deals with delexical structures and in particular with the problems non-native speakers are faced with when encoding. First, it gives reasons why it is necessary to study the structures and then it discusses the delexical structures in English (monolingual context. The second part of the article focuses on the bilingual aspect, i.e. the translation of English delexical structures into Slovene. Some problems concerning the bilingual context are presented, especially as regards aspect and the difference between the translation of English delexical structures in isolation (e.g. in a dictionary and within the context. The last part of the article concentrates on the dictionary treatment of delexical structures and provides some examples taken from the latest editions of the leading EFL monolingual dictionaries.

Negotiating the city: Exploring the intersecting vulnerabilities of non-national migrant mothers who sell sex in Johannesburg, South Africa

NARCIS (Netherlands)

Walker, Becky; Vearey, Jo; Nencel, L.S.

2017-01-01

This article explores the intersecting vulnerabilities of non-national migrant mothers who sell sex in Johannesburg, South Africa – one of the most unequal cities in the world. Migrants who struggle to access the benefits of the city live and work in precarious peripheral spaces where they

Non-national citizens regarding local taxes in Alicante province (1994-2014 / Los ciudadanos no nacionales y los impuestos locales. La atención al contribuyente extranjero en la provincia de Alicante (1994-2014

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Irene Belmonte Martín

2014-10-01

Full Text Available This study offers an overview of the relationship between non-national citizens in the Alicante province – as the dominant province for foreigners -and their input to local taxes- as principal economic resource for municipalities. First, it aims to describe the strategies of the local public tax agency (Suma Gestión Tributaria de la Diputación Provincial de Alicante to achieve better communication with non-national regarding the taxing system. Secondly, it explores the understanding of Suma´s processes for the non-national taxpayer. The motivation is that complete integration of foreigners, as citizens full of rights and duties, with mutual empowerment for the local government and citizens alike.

Home range use and movement patterns of non-native feral goats in a tropical island montane dry landscape

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Mark W. Chynoweth; Christopher A. Lepczyk; Creighton M. Litton; Steven C. Hess; James R. Kellner; Susan Cordell; Lalit Kumar

2015-01-01

Advances in wildlife telemetry and remote sensing technology facilitate studies of broad-scale movements of ungulates in relation to phenological shifts in vegetation. In tropical island dry landscapes, home range use and movements of non-native feral goats (Capra hircus) are largely unknown, yet this information is important to help guide the...

The Big Four Skills: Teachers’ Assumptions on Measurement of Cognition and Academic Skills for Non-Native Students.

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Figueiredo, Sandra; Silva, Carlos Fernandes da; Nunes, Odete; Martins, Maria Margarida Alves d'Orey

2016-01-01

The four-skills on tests for young native speakers commonly do not generate correlation incongruency concerning the cognitive strategies frequently reported. Considering the non-native speakers there are parse evidence to determine which tasks are important to assess properly the cognitive and academic language proficiency (Cummins, 1980; 2012). Research questions: It is of high probability that young students with origin in immigration ...

Phylogeny and evolutionary patterns in the Dwarf crayfish subfamily (Decapoda: Cambarellinae.

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Carlos Pedraza-Lara

Full Text Available The Dwarf crayfish or Cambarellinae, is a morphologically singular subfamily of decapod crustaceans that contains only one genus, Cambarellus. Its intriguing distribution, along the river basins of the Gulf Coast of United States (Gulf Group and into Central México (Mexican Group, has until now lacked of satisfactory explanation. This study provides a comprehensive sampling of most of the extant species of Cambarellus and sheds light on its evolutionary history, systematics and biogeography. We tested the impact of Gulf Group versus Mexican Group geography on rates of cladogenesis using a maximum likelihood framework, testing different models of birth/extinction of lineages. We propose a comprehensive phylogenetic hypothesis for the subfamily based on mitochondrial and nuclear loci (3,833 bp using Bayesian and Maximum Likelihood methods. The phylogenetic structure found two phylogenetic groups associated to the two main geographic components (Gulf Group and Mexican Group and is partially consistent with the historical structure of river basins. The previous hypothesis, which divided the genus into three subgenera based on genitalia morphology was only partially supported (P = 0.047, resulting in a paraphyletic subgenus Pandicambarus. We found at least two cases in which phylogenetic structure failed to recover monophyly of recognized species while detecting several cases of cryptic diversity, corresponding to lineages not assigned to any described species. Cladogenetic patterns in the entire subfamily are better explained by an allopatric model of speciation. Diversification analyses showed similar cladogenesis patterns between both groups and did not significantly differ from the constant rate models. While cladogenesis in the Gulf Group is coincident in time with changes in the sea levels, in the Mexican Group, cladogenesis is congruent with the formation of the Trans-Mexican Volcanic Belt. Our results show how similar allopatric

Imported Asian swamp eels (Synbranchidae: Monopterus) in North American live food markets: Potential vectors of non-native parasites

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Nico, Leo G.; Sharp, Paul; Collins, Timothy M.

2011-01-01

Since the 1990s, possibly earlier, large numbers of Asian swamp eels (Synbranchidae: Monopterus spp.), some wild-caught, have been imported live from various countries in Asia and sold in ethnic food markets in cities throughout the USA and parts of Canada. Such markets are the likely introduction pathway of some, perhaps most, of the five known wild populations of Asian swamp eels present in the continental United States. This paper presents results of a pilot study intended to gather baseline data on the occurrence and abundance of internal macroparasites infecting swamp eels imported from Asia to North American retail food markets. These data are important in assessing the potential role that imported swamp eels may play as possible vectors of non-native parasites. Examination of the gastrointestinal tracts and associated tissues of 19 adult-sized swamp eels—identified as M. albus "Clade C"—imported from Vietnam and present in a U.S. retail food market revealed that 18 (95%) contained macroparasites. The 394 individual parasites recovered included a mix of nematodes, acanthocephalans, cestodes, digeneans, and pentastomes. The findings raise concern because of the likelihood that some parasites infecting market swamp eels imported from Asia are themselves Asian taxa, some possibly new to North America. The ecological risk is exacerbated because swamp eels sold in food markets are occasionally retained live by customers and a few reportedly released into the wild. For comparative purposes, M. albus "Clade C" swamp eels from a non-native population in Florida (USA) were also examined and most (84%) were found to be infected with internal macroparasites. The current level of analysis does not allow us to confirm whether these are non-native parasites.

The Teaching of Pragmatics by Native and Nonnative Language Teachers: What They Know and What They Report Doing

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Cohen, Andrew D.

2016-01-01

The paper focuses on how nonnative teachers of a target language (NNTs) deal with pragmatics in their classes. It starts with a discussion of what pragmatics entails. Next, issues relating to the teaching of pragmatics are identified, such as the language background of the teacher, comparisons between second- (L2) and foreign-language (FL)…

Analysis of trade-offs between threats of invasion by nonnative brook trout (Salvelinus fontinalis) and intentional isolation for native westslope cutthroat trout (Oncorhynchus clarkii lewisi)

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Peterson, D.P.; Rieman, B.E.; Dunham, J.B.; Fausch, K.D.; Young, M.K.

2008-01-01

Native salmonid fishes often face simultaneous threats from habitat fragmentation and invasion by nonnative trout species. Unfortunately, management actions to address one may create or exacerbate the other. A consistent decision process would include a systematic analysis of when and where intentional use or removal of barriers is the most appropriate action. We developed a Bayesian belief network as a tool for such analyses. We focused on native westslope cutthroat trout (Oncorhynchus clarkii lewisi) and nonnative brook trout (Salvelinus fontinalis) and considered the environmental factors influencing both species, their potential interactions, and the effects of isolation on the persistence of local cutthroat trout populations. The trade-offs between isolation and invasion were strongly influenced by size and habitat quality of the stream network to be isolated and existing demographic linkages within and among populations. An application of the model in several sites in western Montana (USA) showed the process could help clarify management objectives and options and prioritize conservation actions among streams. The approach can also facilitate communication among parties concerned with native salmonids, nonnative fish invasions, barriers and intentional isolation, and management of the associated habitats and populations. ?? 2008 NRC.

Assessment of Nonnative Invasive Plants in the DOE Oak Ridge National Environmental Research Park

Energy Technology Data Exchange (ETDEWEB)

Drake, S.J.

2002-11-05

The Department of Energy (DOE) National Environmental Research Park at Oak Ridge, Tennessee, is composed of second-growth forest stands characteristic of much of the eastern deciduous forest of the Ridge and Valley Province of Tennessee. Human use of natural ecosystems in this region has facilitated the establishment of at least 167 nonnative, invasive plant species on the Research Park. Our objective was to assess the distribution, abundance, impact, and potential for control of the 18 most abundant invasive species on the Research Park. In 2000, field surveys were conducted of 16 management areas on the Research Park (14 Natural Areas, 1 Reference Area, and Walker Branch Watershed) and the Research Park as a whole to acquire qualitative and quantitative data on the distribution and abundance of these taxa. Data from the surveys were used to rank the relative importance of these species using the ''Alien Plant Ranking System, Version 5.1'' developed by the U.S. Geological Survey. Microstegium (Microstegium vimineum) was ranked highest, or most problematic, for the entire Research Park because of its potential impact on natural systems, its tendency to become a management problem, and how difficult it is to control. Microstegium was present in 12 of the 16 individual sites surveyed; when present, it consistently ranked as the most problematic invasive species, particularly in terms of its potential impact on natural systems. Japanese honeysuckle (Lonicera japonica) and Chinese privet (Ligustrum sinense) were the second- and third-most problematic plant species on the Research Park; these two species were present in 12 and 9 of the 16 sites surveyed, respectively, and often ranked second- or third-most problematic. Other nonnative, invasive species, in decreasing rank order, included kudzu (Pueraria montma), multiflora rose (Rosa multiflora), Chinese lespedeza (Lespedeza cuneara), and other species representing a variety of life forms and growth

Evaluation of Arabic Language Learning Program for Non-Native Speakers in Saudi Electronic University According to Total Quality Standards

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Alowaydhi, Wafa Hafez

2016-01-01

The current study aimed at standardizing the program of learning Arabic for non-native speakers in Saudi Electronic University according to certain standards of total quality. To achieve its purpose, the study adopted the descriptive analytical method. The author prepared a measurement tool for evaluating the electronic learning programs in light…

Conservation and restoration of forest trees impacted by non-native pathogens: the role of genetics and tree improvement

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R.A. Sniezko; L.A. Winn

2017-01-01

North American native tree species in forest ecosystems, as well as managed forests and urban plantings, are being severely impacted by pathogens and insects. The impacts of these pathogens and insects often increase over time, and they are particularly acute for those species affected by non-native pathogens and insects. For restoration of affected tree species or for...

Non-native fishes of the central Indian River Lagoon

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Schofield, Pamela J.; Loftus, William F.; Reaver, Kristen M.

2018-01-01

We provide a comprehensive review of the status of non-native fishes in the central Indian River Lagoon (from Cape Canaveral to Grant-Valkaria, east of I-95) through literature review and field surveys. Historical records exist for 17 taxa (15 species, one hybrid, one species complex). We found historical records for one additional species, and collected one species in our field survey that had never been recorded in the region before (and which we eradicated). Thus, we evaluate 19 total taxa herein. Of these, we documented range expansion of four salt-tolerant cichlid species, extirpation of six species that were previously recorded from the area and eradication of three species. There was no noticeable change in geographic range for one widespread species and the records for one species are doubtful and may be erroneous. Currently, there is not enough information to evaluate geographic ranges for four species although at least one of those is established.

Monolingual and Bilingual Infants’ Ability to Use Non-native Tone for Word Learning Deteriorates by the Second Year After Birth

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Liquan Liu

2018-03-01

Full Text Available Previous studies reported a non-native word learning advantage for bilingual infants at around 18 months. We investigated developmental changes in infant interpretation of sounds that aid in object mapping. Dutch monolingual and bilingual (exposed to Dutch and a second non-tone-language infants’ word learning ability was examined on two novel label–object pairings using syllables differing in Mandarin tones as labels (flat vs. falling. Infants aged 14–15 months, regardless of language backgrounds, were sensitive to violations in the label–objects pairings when lexical tones were switched compared to when they were the same as habituated. Conversely at 17–18 months, neither monolingual nor bilingual infants demonstrated learning. Linking with existing literature, infants’ ability to associate non-native tones with meanings may be related to tonal acoustic properties and/or perceptual assimilation to native prosodic categories. These findings provide new insights into the relation between infant tone perception, learning, and interpretative narrowing from a developmental perspective.

Non-Native Ambrosia Beetles as Opportunistic Exploiters of Living but Weakened Trees.

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Ranger, Christopher M; Schultz, Peter B; Frank, Steven D; Chong, Juang H; Reding, Michael E

2015-01-01

Exotic Xylosandrus spp. ambrosia beetles established in non-native habitats have been associated with sudden and extensive attacks on a diverse range of living trees, but factors driving their shift from dying/dead hosts to living and healthy ones are not well understood. We sought to characterize the role of host physiological condition on preference and colonization by two invaders, Xylosandrus germanus and Xylosandrus crassiusculus. When given free-choice under field conditions among flooded and non-flooded deciduous tree species of varying intolerance to flooding, beetles attacked flood-intolerant tree species over more tolerant species within 3 days of initiating flood stress. In particular, flood-intolerant flowering dogwood (Cornus florida) sustained more attacks than flood-tolerant species, including silver maple (Acer saccharinum) and swamp white oak (Quercus bicolor). Ethanol, a key host-derived attractant, was detected at higher concentrations 3 days after initiating flooding within stems of flood intolerant species compared to tolerant and non-flooded species. A positive correlation was also detected between ethanol concentrations in stem tissue and cumulative ambrosia beetle attacks. When adult X. germanus and X. crassiusculus were confined with no-choice to stems of flood-stressed and non-flooded C. florida, more ejected sawdust resulting from tunneling activity was associated with the flood-stressed trees. Furthermore, living foundresses, eggs, larvae, and pupae were only detected within galleries created in stems of flood-stressed trees. Despite a capability to attack diverse tree genera, X. germanus and X. crassiusculus efficiently distinguished among varying host qualities and preferentially targeted trees based on their intolerance of flood stress. Non-flooded trees were not preferred or successfully colonized. This study demonstrates the host-selection strategy exhibited by X. germanus and X. crassiusculus in non-native habitats involves

Non-Native Ambrosia Beetles as Opportunistic Exploiters of Living but Weakened Trees.

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Christopher M Ranger

Full Text Available Exotic Xylosandrus spp. ambrosia beetles established in non-native habitats have been associated with sudden and extensive attacks on a diverse range of living trees, but factors driving their shift from dying/dead hosts to living and healthy ones are not well understood. We sought to characterize the role of host physiological condition on preference and colonization by two invaders, Xylosandrus germanus and Xylosandrus crassiusculus. When given free-choice under field conditions among flooded and non-flooded deciduous tree species of varying intolerance to flooding, beetles attacked flood-intolerant tree species over more tolerant species within 3 days of initiating flood stress. In particular, flood-intolerant flowering dogwood (Cornus florida sustained more attacks than flood-tolerant species, including silver maple (Acer saccharinum and swamp white oak (Quercus bicolor. Ethanol, a key host-derived attractant, was detected at higher concentrations 3 days after initiating flooding within stems of flood intolerant species compared to tolerant and non-flooded species. A positive correlation was also detected between ethanol concentrations in stem tissue and cumulative ambrosia beetle attacks. When adult X. germanus and X. crassiusculus were confined with no-choice to stems of flood-stressed and non-flooded C. florida, more ejected sawdust resulting from tunneling activity was associated with the flood-stressed trees. Furthermore, living foundresses, eggs, larvae, and pupae were only detected within galleries created in stems of flood-stressed trees. Despite a capability to attack diverse tree genera, X. germanus and X. crassiusculus efficiently distinguished among varying host qualities and preferentially targeted trees based on their intolerance of flood stress. Non-flooded trees were not preferred or successfully colonized. This study demonstrates the host-selection strategy exhibited by X. germanus and X. crassiusculus in non-native habitats

Unpacking Race, Culture, and Class in Rural Alaska: Native and Non-Native Multidisciplinary Professionals' Perceptions of Child Sexual Abuse

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Bubar, Roe; Bundy-Fazioli, Kimberly

2011-01-01

The purpose of this study was to unpack notions of class, culture, and race as they relate to multidisciplinary team (MDT) professionals and their perceptions of prevalence in child sexual abuse cases in Native and non-Native rural Alaska communities. Power and privilege within professional settings is significant for all social work professionals…

The Hydrodynamic Distinctiveness of Living Organisms: Communication in Complex Hydraulic Environments

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Johnson, M.

2015-12-01

Animals make decisions about the suitability of habitat and their reaction to other organisms based on the sensory information that they first obtain. This information is transmitted, masked and filtered by fluvial processes, such as turbulent flow. Despite governing how animals interact with the environment, limited attention has been paid to the controls on the propagation of sensory signals through rivers. Some animals interpret hydraulic events and use the characteristics of wakes to sense the presence of other organisms. This implies that at least some animals can differentiate turbulent flow generated by the presence of living organisms from ambient environmental turbulence. We investigate whether there are specific flow characteristics, distinct from the ambient environment, that potentially flag the presence of organisms to other animals. ADV and PIV measurements in a series of laboratory flume experiments quantified the flow around living Signal Crayfish (Pacifastacus leniusculus) and two inanimate objects of equivalent shape and size. Experiments were repeated across a gradient of turbulence intensities generated over nine combinations of flow velocity and relative submergence. Flows downstream of living crayfish were distinct from inanimate objects, with greater turbulent intensities, higher energy in low- to intermediate frequencies, and flow structures that were less coherent in comparison to those measured downstream of inanimate objects. However, the hydrodynamic signature of crayfish became masked as the intensity of ambient turbulence exceeded that generated by living crayfish. These results demonstrate the importance of the fluvial processes in the transmission of sensory information and suggest that the ability of animals to perceive hydraulic signatures is likely to be limited in many situations in rivers. Thus, animals may need to rely on other senses, such as sight or hearing, especially where depth is shallow relative to grain size.

Nonnative invasive plants in the Penobscot Experimental Forest in Maine, USA: influence of site, silviculture, and land use history

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Elizabeth Olson; Laura S. Kenefic; Alison C. Dibble; John C. Brissette

2011-01-01

We investigated the occurrence of nonnative invasive plants on approximately 175 ha comprising a long-term, 60-year-old U.S. Forest Service silvicultural experiment and old-field stands in the Penobscot Experimental Forest (PEF) in central Maine. Stands in the silvicultural experiment were never cleared for agriculture, but have been repeatedly partially cut. Our...

The Development and Validation of the "Academic Spoken English Strategies Survey (ASESS)" for Non-Native English Speaking Graduate Students

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Schroeder, Rui M.

2016-01-01

This study reports on the three-year development and validation of a new assessment tool--the Academic Spoken English Strategies Survey (ASESS). The questionnaire is the first of its kind to assess the listening and speaking strategy use of non-native English speaking (NNES) graduate students. A combination of sources was used to develop the…

The interactive effects of climate change, riparian management, and a nonnative predator on stream-rearing salmon.

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Lawrence, David J; Stewart-Koster, Ben; Olden, Julian D; Ruesch, Aaron S; Torgersen, Christian E; Lawler, Joshua J; Butcher, Don P; Crown, Julia K

2014-06-01

Predicting how climate change is likely to interact with myriad other stressors that threaten species of conservation concern is an essential challenge in aquatic ecosystems. This study provides a framework to accomplish this task in salmon-bearing streams of the northwestern United States, where land-use-related reductions in riparian shading have caused changes in stream thermal regimes, and additional warming from projected climate change may result in significant losses of coldwater fish habitat over the next century. Predatory, nonnative smallmouth bass have also been introduced into many northwestern streams, and their range is likely to expand as streams warm, presenting an additional challenge to the persistence of threatened Pacific salmon. The goal of this work was to forecast the interactive effects of climate change, riparian management, and nonnative species on stream-rearing salmon and to evaluate the capacity of restoration to mitigate these effects. We intersected downscaled global climate forecasts with a local-scale water temperature model to predict mid- and end-of-century temperatures in streams in the Columbia River basin. We compared one stream that is thermally impaired due to the loss of riparian vegetation and another that is cooler and has a largely intact riparian corridor. Using the forecasted stream temperatures in conjunction with fish-habitat models, we predicted how stream-rearing chinook salmon and bass distributions would change as each stream warmed. In the highly modified stream, end-of-century warming may cause near total loss of chinook salmon-rearing habitat and a complete invasion of the upper watershed by bass. In the less modified stream, bass were thermally restricted from the upstream-most areas. In both systems, temperature increases resulted in higher predicted spatial overlap between stream-rearing chinook salmon and potentially predatory bass in the early summer (two- to fourfold increase) and greater abundance of