Browsing by Subject "food web"

Now showing 1 - 3 of 3
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    Data and R code for analysis of mercury concentration and food web differences in walleye and yellow perch from Minnesota lakes with and without invasive zebra mussels, 2019 - 2021
    (2023-02-24) Blinick, Naomi S; Ahrenstorff, Tyler D; Bethke, Bethany J; Fleishman, Abram B; Link, Denver; Nelson, Jenna KR; Rantala, Heidi M; Rude, Claire L; Hansen, Gretchen JA; nsblinick@gmail.com; Blinick, Naomi S; University of Minnesota Department of Fisheries, Wildlife, Conservation Biology; Minnesota Department of Natural Resources
    This dataset contains δ13C and δ15N stable isotope data for 3,765 biological samples (fish, littoral macroinvertebrates, and zooplankton) collected from 21 lakes between 2019 and 2021, collaboratively by the University of Minnesota and the Minnesota Department of Natural Resources. In addition, 403 samples have corresponding mercury data, based on laboratory analyses conducted by USGS (Tate et al. 2022).
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    Long-Term Population Growth And Food Web Impacts Of The Spiny Water Flea (Bythotrephes Longimanus) Revealed From Sediment Records
    (2020-03) DeWeese, Nichole
    The spiny water flea (Bythotrephes longimanus) is an invasive predacious zooplankton species that has well-documented impacts on aquatic food webs. However, few studies have examined long-term population dynamics and food web impacts of the species. This study used Bythotrephes subfossils, as well as subfossils from potential prey and competitor taxa (bosminids, daphniids, Simocephalus, and Leptodora kindtii) and pigment concentrations in 210Pb dated sediment cores from Mille Lacs Lake and Kabetogama Lake in Minnesota, USA to estimate first invasion and population growth of Bythotrephes and corresponding impacts on the lower food web. Bythotrephes evidence was found nearly 100 years prior to first detection in each lake, potentially making these lakes the earliest invaded lakes in North America. Bythotrephes subfossils slowly accumulated until around 1990, when accumulation rates rapidly increased. Two-piece linear models provided a good fit for Bythotrephes annual accumulation rates (a proxy for population size), and modelled lag phases lasted approximately 70 years in each lake. Of the native zooplankton species, Bosmina was the only species group that declined in correspondence with Bythotrephes population growth. Bosmina antennules and mucros were measured to analyze if morphological changes occurred as Bythotrephes populations grew, but these feature lengths did not consistently change over time. Sediment pigment concentrations did not increase with Bythotrephes population growth as expected in either lake. This research suggests that 1) Bythotrephes could be present in lakes decades before detection in zooplankton net samples, 2) populations take several decades to overcome lag phases, and 3) that other ecosystem factors may be more important than Bythotrephes in driving long-term food web changes in these lakes.
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    Zebra mussel invasion associated with higher reliance on littoral energy sources and higher mercury levels in walleye and yellow perch
    (2022-02) Blinick, Naomi
    Zebra mussels (Dreissena polymorpha), an aquatic invasive species, shift lake food resources from the pelagic to the littoral zone, while simultaneously altering physical habitat by increasing water clarity. Using stable isotope analysis, we find that walleye (Sander vitreus), a specialist piscivore with strict habitat requirements, and yellow perch (Perca flavescens), a generalist in both diet and habitat, respond similarly to food web and habitat differences in zebra mussel invaded lakes, with significant increases in littoral reliance from ~50% to ~75% for both species. We also report a correlated increase in mercury concentrations in fish tissue, which were 66% higher for adult walleye and 90% higher for adult yellow perch in lakes containing zebra mussels. Considering the importance of these fish for consumption, it is critical that we understand how changes to nutrient cycling and lake food webs ultimately increase toxin concentration in fish consumed by humans.