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USGS - science for a changing world


James H Larson

Research Fishery Biologist

Upper Midwest Environmental Sciences Center

Office Phone: 608-781-6231
ORCID: 0000-0002-6414-9758

UMESC - Laboratory/Office - #1
2630 Fanta Reed Road
La Crosse , WI 54603

Supervisor: Mark T Wiltermuth
Invasion of North American waters by Dreissena polymorpha and D. rostriformis bugensis has resulted in declines in native North American Unionoida mussels. Dreissenid mussels biofoul unionid mussels in large numbers and interfere with unionid movement, acquisition of food and ability to open and close their shells. Initial expectations for the Great Lakes were that unionids would be extirpated where they co-occur with dreissenids, but recently adult and juvenile unionids have been found alive in several apparent refugia. These unionid populations may persist due to reduced dreissenid biofouling in these areas, and/or due to processes that remove biofoulers. For example, locations inaccessible to veligers may reduce...
In 2013 and 2014, standardized electrofishing was conducted above and below Lock and Dam 19 (i.e., in Pools 19 and 20 respectively) of the Upper Mississippi River (UMR). Sampling was consistent with the UMR Restoration program’s Long Term Resource Monitoring element (LTRM) and The Illinois Natural History Survey’s Long Term Electrofishing program (LTEF) allowing for standardized comparisons among the reaches we sampled and those sampled by the LTRM (Pools 4, 8, 13, and 26) and LTEF (Pools 16-21, and Pool 25). Data in this file is includes A) new data from Pools 19 and 20 and B) data compiled from public sources for other pools (LTRM and LTEF). Generally, data codes are intended to match formatting conventions from...
This dataset includes information from ichthyoplankton sampling for silver carp and bighead carp collected from three main reaches in the Upper Mississippi River Basin, including the La Grange, Peoria, Starved Rock, and Marseilles reaches of the Illinois River, Pool 20 of Mississippi River, and the St. Croix River. Data include the number of bigheaded carp eggs and larvae identified using traditional manual sorting techniques, and genetic data derived from quantitative PCR (qPCR) and 4 bigheaded carp markers (SCTM4/5 and BHTM1/2) that were used to identify the amount of DNA in ichthyoplankton tow samples. These data provide information for natural resource agencies and managers who could use this qPCR screening...
Description of Work The GLRI Rivermouths Project (template 82) is designed to enhance our understanding of how rivermouths function at both regional and local scales by 1) developing a rivermouth classification system, based on a broad scale database covering all Great Lakes rivermouths (>2000); 2) creating a science-based understanding of how the ecological structure and function of rivermouths are linked both to the landscapes they drain and to the Lakes with which they mix; and 3) increasing the public and scientific profile of these ecosystems by connecting researchers and natural resource managers through a collaborative dialog. The long-term goal is to provide enhanced guidance for restoration and rehabilitation...
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...
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