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Norman D. Yan - One of the best experts on this subject based on the ideXlab platform.
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a review of the effects of Bythotrephes longimanus and calcium decline on zooplankton communities can interactive effects be predicted
Environmental Reviews, 2015Co-Authors: Shakira S E Azan, Shelley E Arnott, Norman D. YanAbstract:Anthropogenic stressors including acid deposition, invasive species, and calcium (Ca) decline have produced widespread damage to Canadian Shield lakes, especially to their zooplankton communities. Here, we review current knowledge on the individual effects on zooplankton by the non-indigenous predator Bythotrephes longimanus and Ca decline; we identify knowledge gaps in this literature and examine the likely interactive impacts of Bythotrephes invasions and Ca decline on zooplankton. The negative impacts of Bythotrephes longimanus on zooplankton communities are well known, whereas current understanding of the effects of declining Ca on zooplankton is restricted to Daphnia spp.; hence, there is a large knowledge gap on how declining Ca may affect zooplankton communities in general. The co-occurring impacts of Bythotrephes and declining Ca have rarely been studied at the species level, and we expect daphniids, particularly Daphnia retrocurva and Daphnia pulicaria, to be the most sensitive to both stressors....
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eicosapentaenoic acid limitation decreases weight and fecundity of the invading predator Bythotrephes longimanus
Journal of Plankton Research, 2014Co-Authors: Natalie Kim, Michael T Arts, Norman D. YanAbstract:Bythotrephes longimanus is an invasive predatory cladoceran that is negatively impacting North American zooplankton in the Laurentian Great Lakes and on the Canadian Shield. Concurrently, algal community composition, which affects zooplankton food quality, is changing in many lakes of the Canadian Shield. The n-3 fatty acid eicosapentaenoic acid (EPA) is highly retained in Bythotrephes, but the effects of EPA limitation on Bythotrephes’ population dynamics are unknown. To test the hypothesis that EPA limitation results in decreased weight and fecundity of Bythotrephes, the green alga Scenedesmus obliquus was cultured in the laboratory, split into EPA-enriched lines and un-enriched controls, then fed to Daphnia ambigua, which were in turn offered to juvenile Bythotrephes. Bythotrephes consuming EPA-enriched daphniids were heavier and had larger clutch sizes than those consuming control daphniids. Both diets supported ontogenesis, but not brood release, of Bythotrephes. To understand why laboratory-reared Bythotrephes did not release broods, we compared their fatty acid profiles with those of field-collected specimens, and found that they were EPA impoverished compared with field-collected conspecifics. Our results suggest that EPA availability influences Bythotrephes population dynamics, establishment success and impacts in nature.
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food limitation impacts life history of the predatory cladoceran Bythotrephes longimanus an invader to north america
Hydrobiologia, 2013Co-Authors: Natalie Kim, Norman D. YanAbstract:North American invasions of the predatory cladoceran Bythotrephes longimanus have resulted in declines in native zooplankton abundance, species richness, and diversity. In the field, population maxima of Bythotrephes are positively correlated to those of their zooplankton prey. To test the hypothesis that increased prey availability enhances Bythotrephes fitness, we reared Bythotrephes in the laboratory on three mixed-species prey densities (equivalent to 15, 30, and 45 prey organisms day−1; designated “low,” “medium,” and “high” food treatments, respectively) over 22 days at 21°C. Bythotrephes consumed the daily equivalent of 9, 14, and 22 prey organisms at the low, medium, and high food densities. Smaller, slower prey were most often selected. Indeed, with increasing prey density, Bythotrephes’ predation rates increased, resulting in significantly higher population growth rates, net reproductive rates, growth, and first brood clutch and offspring sizes; significantly faster generation times; and shorter maximum life spans. We propose that the positive relationship between Bythotrephes population maxima and prey seen in the field is largely due to increased predation rates by Bythotrephes when prey abundance is high and the fitness benefits that ensue. Our findings may be useful for Bythotrephes risk and impact assessments.
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dynamics of the invasive spiny water flea Bythotrephes longimanus in lake simcoe ontario canada
Inland Waters, 2013Co-Authors: Noreen E Kelly, Joelle D Young, Jennifer G Winter, Norman D. YanAbstract:The invasion of the nonindigenous zooplankter Bythotrephes longimanus in Lake Simcoe has the potential to impact overall ecosystem functioning, yet there is currently no information regarding the status and dynamics of its population. We used a combination of uni- and multivariate analyses to examine variation in Bythotrephes interannual and seasonal abundance, and life-history characteristics in Lake Simcoe from 1999 to 2007, and we explored the biotic (predators, prey) and/or abiotic (water quality, temperature) factors that may have regulated its population over this period. The mean annual abundance of Bythotrephes varied by an order of magnitude over the period of study and was significantly associated with epilimnetic temperature and prey and predator abundance. Bythotrephes typically appeared in early summer and had 2 seasonal abundance peaks, which varied in magnitude and timing within and among years. August and September Secchi depth and total phosphorus concentration predicted groups of years with similar Bythotrephes phenologies, lending further support to the role of water clarity as a significant component of this visual predator’s habitat in its invaded range. Bythotrephes body size and reproductive patterns also varied seasonally, possibly reflecting the seasonal availability of cladoceran prey, predation pressure from planktivorous fish, or adaptations to avoid unfavourable conditions. Overall, a complex interaction of fish predation, food availability, temperature, and water clarity controlled the dynamics of Bythotrephes in Lake Simcoe. Changes to the Lake Simcoe ecosystem due to Bythotrephes invasion may have important consequences for the ecosystem services provided by the lake and merit further investigation.
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shifting invertebrate zooplanktivores watershed level replacement of the native leptodora by the non indigenous Bythotrephes in canadian shield lakes
Biological Invasions, 2011Co-Authors: Erika Weisz, Norman D. YanAbstract:The abundance of the native, pelagic macroinvertebrate predator, Leptodora kindtii, is negatively correlated with the abundance of a new invasive competitor, Bythotrephes longimanus, in a small number of Canadian Shield lakes. However, we do not yet know if Bythotrephes is replacing Leptodora on a regional scale. We determined the distribution of both species in 166 lakes in the District of Muskoka, south-central Ontario, Canada—the watershed with the longest history and largest prevalence of Bythotrephes invasions in North America. The frequency of occurrence of Leptodora was substantially reduced (twofold) in the presence of Bythotrephes. We argue that Bythotrephes is responsible for this dramatic reduction in the frequency of occurrence of Leptodora. Lakes in which both species co-occurred could not be distinguished from invaded lakes without Leptodora, suggesting a pattern of species replacement at a watershed level. We believe this is the first account of the widespread replacement of a native, pelagic macroinvertebrate predator by Bythotrephes in North America, and it does not bode well for Leptodora given the rapid, ongoing spread of Bythotrephes.
Shelley E Arnott - One of the best experts on this subject based on the ideXlab platform.
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taxonomic resolution of the north american invasive species of the genus Bythotrephes leydig 1860 crustacea cladocera cercopagididae
Zootaxa, 2019Co-Authors: Nikolai M Korovchinsky, Shelley E ArnottAbstract:The invasive species of the genus Bythotrephes introduced in the North American lakes in 1970s-early 1980s was named variously either B. cederstroemi or B. longimanus. The investigation of individuals of the genus from 15 Canadian lakes has allowed us to identify all of them as B. cederstromii Schodler, based on the detailed taxonomic redescription of the Eurasian representatives of the species. The available documented data (figures and photographs) on Bythotrephes from other North American lakes, made it possible to recognize their identity with this species as well. The possible introduction of interspecific hybrids of the genus Bythotrephes in the North American lakes has not been confirmed.
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anti predator behaviour of native prey daphnia to an invasive predator Bythotrephes longimanus is influenced by predator density and water clarity
Hydrobiologia, 2019Co-Authors: Sarah Hasnain, Shelley E ArnottAbstract:Bythotrephes longimanus is an invasive zooplankton predator, negatively impacting zooplankton abundance and diversity in North American lakes. Previous studies have shown that Daphnia populations in lakes move to deeper waters during the day, in the presence of Bythotrephes, a visual predator occupying well-lit regions. However, Daphnia vertical position can be influenced by a variety of biotic and abiotic factors. We conducted a survey to determine (1) if Daphnia daytime vertical position differed between invaded and uninvaded lakes and (2) if Daphnia vertical position in invaded lakes was affected by water chemistry variables linked to water clarity, UV exposure, and phytoplankton production, and Bythotrephes density. Invaded lakes had a lower proportion of epilimnetic Daphnia as compared to uninvaded lakes. Daphnia vertical position was species-dependent, and with a lower proportion of epilimnetic Daphnia mendotae and greater proportion of epilimnetic D. longiremis observed in invaded lakes. D. mendotae were deeper in the water column in high Bythotrephes density lakes with low dissolved organic carbon levels. Our results show Daphnia vertical position response to Bythotrephes is species specific, dependent on Bythotrephes density and influenced by local abiotic conditions, with important implications for community structure and ecosystem function in invaded lakes.
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the effects of Bythotrephes longimanus and calcium decline on crustacean zooplankton communities in canadian shield lakes
Hydrobiologia, 2017Co-Authors: Shakira S E Azan, Shelley E ArnottAbstract:Declining calcium concentrations and invasion by Bythotrephes longimanus are two important, often co-occurring, stressors affecting Canadian Shield lakes. However, there has been no experimental examination of how they might jointly influence zooplankton communities. We conducted a 6-week field mesocosm experiment in Havelock Lake, Haliburton, Ontario, Canada to examine the individual and joint effects of Bythotrephes and calcium along a gradient ranging from 1.2 to 2.6 mg/l on zooplankton communities. Although densities of Bythotrephes in our study are unknown, it significantly reduced total zooplankton abundance in invaded compared to uninvaded treatments by 46%, with the greatest impacts on small cladocerans and daphniids. Low calcium reduced total zooplankton and cladoceran abundances. Although Havelock Lake has the lowest calcium concentration among invaded lakes in the Muskoka–Haliburton region (1.2 mg Ca/l), an effect of calcium on individual species abundances was not detected. Additionally, we did not detect an interactive effect of both stressors. Our results suggest that lake calcium concentration may not yet be low enough to effect a strong response. However, as Bythotrephes continue to invade low calcium lakes, and as calcium concentrations further decline, we may see larger impacts on cladocerans as calcium thresholds for reproduction and growth are reached.
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a review of the effects of Bythotrephes longimanus and calcium decline on zooplankton communities can interactive effects be predicted
Environmental Reviews, 2015Co-Authors: Shakira S E Azan, Shelley E Arnott, Norman D. YanAbstract:Anthropogenic stressors including acid deposition, invasive species, and calcium (Ca) decline have produced widespread damage to Canadian Shield lakes, especially to their zooplankton communities. Here, we review current knowledge on the individual effects on zooplankton by the non-indigenous predator Bythotrephes longimanus and Ca decline; we identify knowledge gaps in this literature and examine the likely interactive impacts of Bythotrephes invasions and Ca decline on zooplankton. The negative impacts of Bythotrephes longimanus on zooplankton communities are well known, whereas current understanding of the effects of declining Ca on zooplankton is restricted to Daphnia spp.; hence, there is a large knowledge gap on how declining Ca may affect zooplankton communities in general. The co-occurring impacts of Bythotrephes and declining Ca have rarely been studied at the species level, and we expect daphniids, particularly Daphnia retrocurva and Daphnia pulicaria, to be the most sensitive to both stressors....
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influence of light on the foraging impact of an introduced predatory cladoceran Bythotrephes longimanus
Freshwater Biology, 2013Co-Authors: Anneli Jokela, Shelley E ArnottAbstract:Summary Identifying factors that influence the foraging ability of an introduced predator is essential for assessing its potential impact on the invaded community. We conducted a series of in situ enclosure experiments to determine the effect of light on the foraging ability and community-level effects of the invasive cladoceran Bythotrephes longimanus in lakes. In 1-L enclosures with only Daphnia prey, a strong effect of predation under ambient light conditions was observed. There was no evidence of predation in dark treatments, suggesting that Bythotrephes is unable to feed by mechanoreception alone. A subsequent experiment using larger enclosures exposed an assemblage of prey from an uninvaded lake to Bythotrephes predation across a similar light gradient. Consistent with regional lake surveys, Bythotrephes reduced cladoceran abundance under ambient light conditions. At the community level, predation effects were overall strongest under ambient light; however, the influence of light on predation varied across trials that differed in initial community structure of prey. Also, some predation under dark conditions was possible on Ceriodaphnia and Bosmina, suggesting that Daphnia, in particular, may be less vulnerable under low-light conditions. Our results suggest that light refuges for some prey taxa could play an important role in mediating the impact of Bythotrephes.
Angela L. Strecker - One of the best experts on this subject based on the ideXlab platform.
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effects of Bythotrephes longimanus crustacea cladocera on the abundance morphology and prey community of leptodora kindtii crustacea cladocera
Hydrobiologia, 2012Co-Authors: Angela L. Strecker, Gary W Sprules, Sophie E FosterAbstract:We hypothesized that native Leptodora kindtii would be shorter and have smaller feeding baskets in central Ontario lakes with greater abundances of small-bodied zooplankton prey, and that differences in zooplankton size among lakes could be attributed to the invasive cladoceran Bythotrephes longimanus. We evaluated these conjectures by comparing size metrics of Leptodora and the size of their preferred cladoceran prey in lakes invaded or not by Bythotrephes. Leptodora was less abundant in invaded lakes, but were smaller bodied with smaller feeding baskets only in lakes with long invasion histories. Small cladoceran abundance was greater in non-invaded lakes and was directly related to Leptodora abundance although not to Leptodora size. Mean Leptodora body size declined with increasing abundance of Bythotrephes. We evaluated three possible explanations for these patterns in Leptodora—(a) competition with Bythotrephes for zooplankton prey, (b) direct predation by Bythotrephes, and (c) size-selective predation by fish. While we were unable to unequivocally distinguish among these hypotheses, our observations are most consistent with predation by Bythotrephes changing zooplankton community composition and size structure in a manner that is detrimental to Leptodora. Our results indicate that Bythotrephes invasion may trigger more complex and subtle changes in food webs than previously thought.
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increased abundance of the non indigenous zooplanktivore Bythotrephes longimanus is strongly correlated with greater spring prey availability in canadian shield lakes
Biological Invasions, 2011Co-Authors: Joelle D Young, Angela L. StreckerAbstract:The non-indigenous zooplanktivore, Bythotrephes longimanus, is a large Palaearctic cladoceran that is spreading rapidly in the Great Lakes watershed in North America. As a voracious predator, Bythotrephes can reduce herbivorous cladoceran abundance and diversity; however, the variables that affect its abundance are not well understood. To determine what bottom-up factors are associated with the abundance and seasonal dynamics of established Bythotrephes populations, two Bythotrephes datasets from lakes in south-central Ontario, Canada, were analysed using multiple regression and multivariate analyses: a multi-lake dataset of nine lakes sampled in 2003 and a multi-year dataset of one of these lakes, Harp Lake, sampled from 1994–1998 and 2001–2004. Bottom-up variables tested were Secchi disk depth, epilimnetic temperature, cladoceran (prey) density, total phosphorus, dissolved organic carbon and Chlorophyll a, as well as maximum depth for the multi-lake dataset. In both analyses and datasets, springtime abundance of herbivorous cladocerans was consistently found to be a significant factor associated with Bythotrephes (June–September) abundance; Bythotrephes annual abundance was significantly and positively associated with mean May and June prey abundance, along with mean Secchi disk depth for the multi-lake dataset, and groups of lakes or years with similar Bythotrephes seasonal abundance patterns were predicted by June prey abundance. Additionally, prey availability was the dominant contributor towards changes in weekly Bythotrephes birth rates calculated for two of the study lakes. Our study suggests that prey availability influences Bythotrephes abundance, which provides evidence that Bythotrephes establishment success is affected by the abundance of its prey.
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Bythotrephes invasion elevates trophic position of zooplankton and fish implications for contaminant biomagnification
Biological Invasions, 2011Co-Authors: Angela L. Strecker, Michael D Rennie, Michelle E PalmerAbstract:We estimated the effects of Bythotrephes longimanus invasion on the trophic position (TP) of zooplankton communities and lake herring, Coregonus artedi. Temporal changes in lacustrine zooplankton communities following Bythotrephes invasion were contrasted with non-invaded reference lakes, and along with published information on zooplankton and herring diets, formed the basis of estimated changes in TP. The TP of zooplankton communities and lake herring increased significantly following the invasion of Bythotrephes, whereas TP in reference lakes decreased (zooplankton) or did not change significantly (lake herring) over a similar time frame. Elevated TP following Bythotrephes invasion was most prominent in lakes that also supported the glacial relict, Mysis diluvania, suggesting a possible synergistic interaction between these two species on zooplankton community composition. Our analysis indicated that elevated TPs of zooplankton communities and lake herring are not simply due to the presence of Bythotrephes, but rather reflect changes in the zooplankton community induced by Bythotrephes; namely, a major reduction in the proportion of herbivorous cladoceran biomass and a concomitant increase in the proportion of omnivorous and/or predatory copepod biomass in invaded lakes. We demonstrated that increases in TP of the magnitude reported here can lead to substantial increases in fish contaminant concentrations. In light of these results, we discuss potential mechanisms that may be responsible for the disconnect between empirical and theoretical evidence that mid-trophic level species invasions (e.g., Bythotrephes) elevate contaminant burdens of consumer species, and provide testable hypotheses to evaluate these mechanisms.
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invasive predator Bythotrephes has varied effects on ecosystem function in freshwater lakes
Ecosystems, 2008Co-Authors: Angela L. Strecker, Shelley E ArnottAbstract:Bythotrephes longimanus is an invertebrate predator that has invaded the North American Great Lakes and a number of inland lakes, where it preys on crustacean zooplankton. We examined the effect of Bythotrephes on two measures of ecosystem function during a four-month observational study of freshwater lakes on the boreal shield. Bythotrephes-invaded lakes had significantly lower epilimnetic zooplankton abundance and production compared to reference lakes. On average, Bythotrephes consumed 34% of zooplankton production when it was present in lakes. There was some evidence of changes in the timing of zooplankton production, as well as shifts to cooler, less productive habitats, which may lessen the overall effect of the invader on the transfer of energy to higher trophic levels. We experimentally demonstrated a weak trophic cascade where invader predation reduced zooplankton biomass, and subsequently increased phytoplankton growth. However, the response was small in magnitude and not biologically relevant at the whole lake-scale. The most conspicuous effect of Bythotrephes that we measured was a diversion of energy away from native predators at higher trophic levels.
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variation in the response of crustacean zooplankton species richness and composition to the invasive predator Bythotrephes longimanus
Canadian Journal of Fisheries and Aquatic Sciences, 2006Co-Authors: Angela L. Strecker, Norman D. Yan, Shelley E Arnott, Robert GirardAbstract:The predacious invertebrate Bythotrephes longimanus has now invaded >90 freshwater lakes in North Amer- ica. There is some evidence that B. longimanus has a negative effect on summer zooplankton species richness; how- ever, no study has examined the effect of B. longimanus throughout the ice-free season in more than one lake. We visited 10 invaded and 4 reference lakes every 2 weeks from May to September, collecting B. longimanus, crustacean zooplankton, and water chemistry samples. Composite samples were pooled across the study season for each lake. Bythotrephes longimanus significantly reduced cladoceran species richness, diversity, and abundance, and the total zoo- plankton community also exhibited decreased richness, diversity, and abundance. Seasonal sampling was better than synoptic surveys at detecting changes in abundance, but richness estimates were similar. As B. longimanus continues to spread across lake landscapes, we expect it will have profound impacts on local and regional richness and species dis- tribution patterns. Resume : L'invertebre predateur Bythotrephes longimanus a maintenant envahi >90 lacs d'eau douce en Amerique du Nord. Il y a des indications que B. longimanus a un effet negatif sur la richesse specifique du zooplancton d'ete; ce- pendant, aucune etude n'a examine les effets de B. longimanus au cours de la periode sans glace dans plus d'un seul lac a la fois. Nous avons visite 10 lacs envahis par le predateur et 4 lacs temoins a toutes les 2 semaines de mai a septembre et preleve des B. longimanus, des crustaces zooplanctoniques et des echantillons d'eau pour analyse chimique. Nous avons amalgame les echantillons de toute la periode pour chacun des lacs. Bythotrephes longimanus reduit significativement la richesse specifique, la diversite et l'abondance des cladoceres; la communaute totale du zooplancton subit aussi une reduction de richesse, de diversite et d'abondance. L'echantillonnage saisonnier permet mieux que les inventaires synoptiques de detecter les changements d'abondance, mais les estimations de richesse sont semblables par les deux methodes. A mesure que B. longimanus continue de se repandre dans les paysages lacustres, nous prevoyons qu'il aura des repercussions importantes sur les patrons de richesse et de repartition d'especes aux echelles locale et regionale. (Traduit par la Redaction) Strecker et al. 2136
Scott D Peacor - One of the best experts on this subject based on the ideXlab platform.
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Morphological Measurements of Bythotrephes in Canadian Shield Lakes
2016Co-Authors: Andrea L. J. Miehls, Scott D Peacor, Andrew G. McadamAbstract:Morphological Measurements of Bythotrephes in Canadian Shield Lake
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Miehls et al. Evol Appl Data
2016Co-Authors: Andrea L. J. Miehls, Scott D Peacor, Andrew G. McadamAbstract:The Miehls et al. Evol Appl Data.csv file contains the data used to quantify genetic, maternal, and environmental variation in distal spine and body length of Bythotrephes longimanus (the spiny water flea) in Lake Michigan (USA). Each row in the spreadsheet includes field and laboratory information (including clonal line relationships and trait measurements) for a single F2 Bythotrephes born in our laboratory clonal lines. All analyses were completed using data from F2 individuals
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Appendix C. Analysis of the allometry of Bythotrephes distal spine-to-body length.
2016Co-Authors: Andrea L. J. Miehls, Andrew G. Mcadam, Paul E Bourdeau, Scott D PeacorAbstract:Analysis of the allometry of Bythotrephes distal spine-to-body length
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Appendix B. The relationship between Bythotrephes biomass and absolute prey abundance in the hypolimnion.
2016Co-Authors: Kevin L. Pangle, Scott D Peacor, Ora E JohannssonAbstract:The relationship between Bythotrephes biomass and absolute prey abundance in the hypolimnion
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Appendix D. Statistical results for predator kairomone and temperature effects on Bythotrephes morphology and life history.
2016Co-Authors: Andrea L. J. Miehls, Andrew G. Mcadam, Paul E Bourdeau, Scott D PeacorAbstract:Statistical results for predator kairomone and temperature effects on Bythotrephes morphology and life history
W. Charles Kerfoot - One of the best experts on this subject based on the ideXlab platform.
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Pumpkinseed sunfish (Lepomis gibbosus) counter spiny cladoceran (Bythotrephes longimanus) defenses
Journal of Great Lakes Research, 2020Co-Authors: Jaime F. Leduc, Martin M. Hobmeier, W. Charles KerfootAbstract:Abstract How do native species react to the presence of an invader? Consumption by resident fish is important in determining the yearly mortality of the invasive cladoceran Bythotrephes. In aquarium experiments, we discovered that small pumpkinseed sunfish (Lepomis gibbosus) were efficient at removing spines from Bythotrephes longimanus and consuming the adults. Experiments quantified how frequently pumpkinseeds showed successful removal of spines, and compared predatory performance relative to other species of fish. We also checked if Bythotrephes' resting eggs pass through the guts of pumpkinseeds in viable condition. The experiments revealed that pumpkinseed sunfish (45–70 mm total length, TL) from two geographic regions removed spines 87% of the time. Spine-handling techniques allowed pumpkinseeds to consume Bythotrephes faster than other species of small (
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Temperature, recreational fishing and diapause egg connections: dispersal of spiny water fleas (Bythotrephes longimanus)
Biological Invasions, 2011Co-Authors: W. Charles Kerfoot, Martin M. Hobmeier, Foad Yousef, Ryan P. Maki, S. Taylor Jarnagin, James H. ChurchillAbstract:The spiny water flea ( Bythotrephes longimanus ) is spreading from Great Lakes coastal waters into northern inland lakes within a northern temperature-defined latitudinal band. Colonization of Great Lakes coastal embayments is assisted by winds and seiche surges, yet rapid inland expansion across the northern states comes through an overland process. The lack of invasions at Isle Royale National Park contrasts with rapid expansion on the nearby Keweenaw Peninsula. Both regions have comparable geology, lake density, and fauna, but differ in recreational fishing boat access, visitation, and containment measures. Tail spines protect Bythotrephes against young of the year, but not larger fish, yet the unusual thick-shelled diapausing eggs can pass through fish guts in viable condition. Sediment traps illustrate how fish spread diapausing eggs across lakes in fecal pellets. Trillions of diapausing eggs are produced per year in Lake Michigan and billions per year in Lake Michigamme, a large inland lake. Dispersal by recreational fishing is linked to use of baitfish, diapausing eggs defecated into live wells and bait buckets, and Bythothephes snagged on fishing line, anchor ropes, and minnow seines. Relatively simple measures, such as on-site rinsing of live wells, restricting transfer of certain baitfish species, or holding baitfish for 24 h (defecation period), should greatly reduce dispersal.
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Fitting into Food Webs: Behavioral and Functional Response of Young Lake Trout (Salvelinus namaycush) to an Introduced Prey, the Spiny Cladoceran (Bythotrephes cederstroemi)
Journal of Great Lakes Research, 2004Co-Authors: D. Rae Barnhisel, W. Charles KerfootAbstract:Functional response experiments with alternative prey demonstrate how an exotic zooplankter co-exists with salmonid fish in Lake Superior. Young lake trout (Salvelinus namaycush) response to Daphnia, a typical prey genus, and to Bythotrephes, a spined invertebrate predator that invaded North America in the mid-1980s, is examined in a variety of laboratory experiments that span various prey densities, frequencies, experience, and consumer size. Bythotrephes’ caudal spine protects the animal from small fish predation. At intermediate densities, the spiny cladoceran also disrupts foraging behavior of young-of-year fish. Lake trout response to Bythotrephes is dependent on the length of the spine and fish size. The degree to which lake trout are able to discriminate between prey and resume their prior attack rate on Daphnia depends on the absolute density of Daphnia and the frequency with which fish encounter Bythotrephes. For both experienced and naive fish, aversive behavior to Bythotrephes occurs after a certain threshold of encounters. Under conditions of high encounter rates, once aversive behavior is established in YOY fish, foraging efficiency on Daphnia improves because Bythotrephes is recognized and ignored. The density-dependent behavioral and functional responses resemble classical predator reactions to unpalatable prey.
