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USGS - science for a changing world


Robert J Kennedy

Resource managers are currently using reductions in the Upper Mississippi River’s (UMR) water levels during summer to mimic historical water levels and rehabilitate habitats for vegetation and desirable fauna. However, drawdowns may have adverse effects on native mussel populations. Over the past few years, systematic, pool-wide surveys of mussels in Pools 5, 6, and 18 have been conducted. The objective of this study was to characterize the effects of water level drawdown on the mortality, movement, and behavior of a common Lampsilini species, Lampsilis cardium, and a common Amblemini species, Amblema plicata, in Pool 6 of the UMR during 2009 and 2010. About 460 mussels were tagged and followed about weekly during...
Large lakes provide a variety of ecological services to surrounding cities and communities. Many of these services are supported by ecological processes that are threatened by the increasing prevalence of cyanobacterial blooms which occur as aquatic ecosystems experience cultural eutrophication. Over the past 10 years, Lake Erie experienced cyanobacterial blooms of increasing severity and frequency, which have resulted in impaired drinking water for the surrounding communities. Cyanobacterial blooms may impact ecological processes that support other services, but many of these impacts have not been documented. Secondary production (production of primary consumers) is an important process that supports economically...
Understanding the quantity and form of nutrient loading to large lakes is necessary to understand controls over primary production, phytoplankton community composition and the production of phytotoxins. Nutrient loading estimates to large lakes are primarily made at stream gages that are deliberately placed outside the direct influence of lake processes, but these estimates cannot take into account processes that occur in the biologically active river-to-lake transition zone. These transition zones (rivermouths) sometimes alter nutrient concentrations and ratios substantially, but few studies have directly measured processing rates of nutrients within rivermouths. From April through September 2016, we conducted...
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