Please join the Great Lakes Center for a seminar titled “Patterns of long-term dynamics of aquatic communities and water quality parameters in the Great Lakes: Are they synchronized?,” presented by Katya Kovalenko from NRRI at the University of Minnesota, Duluth. All students, staff, and faculty are welcome.
Abstract: Long-time series data can provide insights into dynamics of large lakes. We use the USEPA-GLNPO biological monitoring dataset (phytoplankton, benthos, zooplankton and water quality), collected from 1996 through 2015, to identify whether there is evidence of concordant linear or non-linear trends in community composition, density/ biomass/biovolume and major environmental parameters. We show concurrent changes in some biotic assemblages and water quality variables, particularly in Lakes Michigan and Huron. These include changes in phytoplankton biovolume and zooplankton biomass, increasing invasive Dreissena abundance and decreasing densities of other benthos. Biotic changes are accompanied by pronounced changes in water quality and nutrient ratios, indicating likely stoichiometric shifts affecting entire food webs. Species change-points, identified using threshold indicator taxon analysis, are often less abrupt, but there are clear shifts in most species in each assemblage. The concordance of breakpoints among assemblages or lack thereof provides valuable insight into potential drivers of ecosystem change.
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