Distribution and Abundance of Larval Yellow Perch (Perca flavescens) in Lake St. Clair and the Lower St. Clair River, 2018
Mon, 12/02/2019 - 21:23
Abstract: Spatial and temporal dynamics of fish larvae play an important role in determining year-class strength due to variation in habitat quality and food resources that influence larval growth, development, and survival rates. Surveys conducted during the past decade in the St. Clair-Detroit River System have revealed a decline of yellow perch. Genetic and microchemistry analyses showed that these fish make a substantial contribution to the yellow perch stock in western Lake Erie. Our study examines the spatial and temporal distributions of larval yellow perch in Lake St. Clair and the lower St. Clair River to identify important spawning and nursery areas and other ecological factors influencing their early life history. We employed a lake-wide daytime sampling program in 2018 using paired bongo nets to sample pelagic larvae throughout 33 sample locations beginning in mid-March before yellow perch had hatched and continued through mid-July when larvae were absent from samples. Based on our spatial analysis results, Mitchell Bay and Anchor Bay appear as the primary regions for yellow perch spawning habitat and/or nursery grounds for larvae. It is difficult to conclude which factors are influencing the distribution of yellow perch the greatest, but submerged aquatic vegetation, water temperature and clarity likely influence yellow perch vital rates, based on our study. The results from this study give us a growing understanding of the ecological interactions underlying larval yellow perch and their habitat usage during their early life history.
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Major: Fisheries and Wildlife Science
File Attachments: Lloyd_LSCLarvalYEPDist2018_Final.docx
Changes in aquatic communities resulting from interactions between climate change and invasive aquatic plants in the Adirondacks.
Thu, 02/09/2012 - 11:26
Abstract: Global climate change can act synergistically with invasive species leading to shifts in ecosystem structure and function. We assessed how a rise in water temperature influenced the potential competitive advantage of an invasive aquatic plant, Eurasian watermilfoil, (Myriophyllum spicatum) over a co-occurring native species northern watermilfoil (M. sibiricum). We also examined the interrelationship between water temperature, watermilfoil, and the aquatic ecosystem including periphyton growth and zooplankton abundance. The study was conducted using replicated mesocosms (3785-liter), with water heaters used to provide a range of temperatures. We found that increasing water temperature promoted the likely competitive advantage of the invasive species, M. spicatum: Survival of M. sibiricum plants was lower than that of M. spicatum across all temperature treatments with a mean survival rate of 24% and 96% respectively. M. sibiricum also showed significantly slower rates of plant growth (mean growth of 3.3 cm compared to 7.6 cm for M. spicatum) and reduced vigor compared to M. spicatum, with an average of less than half the number of growing meristems. Zooplankton densities averaged over 20 times higher in mesocosms with M. sibiricum compared to those with the invasive M. spicatum. Periphyton biomass was best explained by water temperature with an increase in growth in warmer water. Our study confirms that in the face of global climate change, the invasive M. spicatum will continue to exert dominance over its native counterpart. Our results also provide compelling evidence that the combined effects of climate change and invasive aquatic plants can dramatically alter aquatic ecosystems.
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Major: Environmental Sciences, Fisheries and Wildlife Science, Forestry, Natural Resources Management and Policy
File Attachments: Climate change and milfoil draft FINAL.doc