| The Minnesota River, like many large rivers, has been functionally altered by human activities and climate change. The Minnesota Pollution Control Agency has designated 271 kilometers (50.3%) of the 539 kilometer Minnesota River as "biologically impaired." However, assessing biological communities in large rivers is often difficult and limited to examination of upper trophic levels (e.g., piscivorous fishes). Few studies examined zooplanktonic communities, largely due to difficulties associated with sampling. Because of the need to improve assessment strategies for biological impairments in the Minnesota River, the zooplanktonic community, including crustaceous zooplankton, rotifers, macroinvertebrates, and ichthyoplankton was evaluated within an impaired and unassessed reaches. Securing a better understand of the early life history of Minnesota River fishes has become a priority to state management agencies. However, to secure necessary data, icthyoplankton sampling strategies must be improve and thus several gears were evaluated during this study.;The zooplanktonic community was sampled from May 2014 to August 2014 and April 2015 to August 2015 in a stretch deemed impaired and an unassessed stretch in the Minnesota River. Gears utilized to sample biota included benthic and surface slednets, light traps with glow-stick or LED light sources, and a Wisconsin vertical trawl. Based on an analysis of similarities, zooplanktonic community composition was more similar between reaches for crustaceous zooplankton (R = 0.02), ichthyoplankton with the slednets (R = 0.03), macroinvertebrates with the light traps ( R = 0.00), macroinvertebrates with the slednets (R = -0.04), and rotifers (R = -0.05) than different. Assessments indicate zooplanktonic communities in both impaired and unassessed reaches of the Minnesota River appear to be degraded as they were similar in a reach deemed impaired and an unassessed reach. Although the total number of zooplanktonic biota captured in both reaches was low, variations in catch rates were noted with changes in hydrology. However, the gears sampled more different portions of the ichthyoplankton community (R = 0.51) than similar portions, demonstrating the value of utilizing multiple gears. |
