Tuesday, June 6, 2017
09:00 - 10:30

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09:00 - 09:15: / 305A FISH, MACROINVERTEBRATE, AND MACROPHYTE COMMUNITY COMPOSITION WITHIN LITTORAL ZONES INVADED BY EURASIAN WATERMILFOIL IN THE KEWEENAW WATERWAY OF LAKE SUPERIOR

6/06/2017  |   09:00 - 09:15   |  305A

FISH, MACROINVERTEBRATE, AND MACROPHYTE COMMUNITY COMPOSITION WITHIN LITTORAL ZONES INVADED BY EURASIAN WATERMILFOIL IN THE KEWEENAW WATERWAY OF LAKE SUPERIOR The invasion of Eurasian watermilfoil (Myriophyllum spicatum) and its hybrids with native Northern watermilfoil (M. spicatum x sibericum) can alter lake littoral zone communities via direct and indirect effects on fish diets, macroinvertebrate assemblages, fish community structure, and native plant abundance. However, relatively little is known about the ecological effects of this invader in colder waters of the upper Great Lakes region. We sampled macroinvertebrates, fish, and macrophytes at sites that represented a gradient of Eurasian watermilfoil and native vegetation abundance in the Keweenaw Waterway of Lake Superior. We hypothesized that sites dominated by Eurasian watermilfoil would support less taxa richness, abundance, as well as smaller size classes of fish, and that macroinvertebrate abundance would be highest in areas of dense vegetation. Fish taxa richness did not significantly differ between sites of native or invasive vegetation. On average, sites with low abundance of Eurasian watermilfoil supported approximately 24% more fish biomass relative to highly invaded habitats. Our results suggest that the spread of Eurasian watermilfoil could alter the size structure of littoral fish communities.

Carmen Leguizamon (Primary Presenter/Author), Michigan Technological University, cmleguiz@mtu.edu;


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09:30 - 09:45: / 305A DIVERGENT RESPONSES IN WATER QUALITY TO INVASION-INDUCED FOOD WEB CHANGES IN A EUTROPHIC LAKE

6/06/2017  |   09:30 - 09:45   |  305A

DIVERGENT RESPONSES IN WATER QUALITY TO INVASION-INDUCED FOOD WEB CHANGES IN A EUTROPHIC LAKE Invasive species can change the functioning of freshwater ecosystems as a result of complex species interactions. Outbreak of the invasive predatory zooplankton, spiny water flea (Bythotrephes longimanus) in Lake Mendota, WI (USA) led to decline in the keystone herbivore Daphnia pulicaria, and in turn, water clarity. We use a 20-year dataset for Lake Mendota and adjacent, invaded Lake Monona to evaluate interactions among nutrients, zooplankton, and phytoplankton that manifested in an invasion-induced trophic cascade. We found that diatom biomass increased in both lakes, driving lower water clarity. However, cyanobacteria biomass did not change in either lake. Multivariate time series analysis revealed that diatoms are likely limited by D. pulicaria grazing while cyanobacteria are more likely limited by nutrients in Lake Mendota. Phosphorus concentrations and export in Lake Mendota have declined with Bythotrephes despite no clear change in loading. Accordingly, the number of beach closures in Lake Mendota due to potentially harmful cyanobacteria blooms decreased despite declining water clarity, suggesting a divergent response in water quality to invasion. Uncoupling of these components of water quality under a food web shift has important implications for water quality management in eutrophic lakes.

Jake Walsh (Primary Presenter/Author), University of Wisconsin - Madison Center for Limnology, jransom.walsh@gmail.com;


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09:45 - 10:00: / 305A EXAMINING RIVERINE DISPERSAL OF ZEBRA MUSSELS (DREISSENA POLYMORPHA) AND THE INVASION RISKS TO TEXAS RESERVOIRS AND STREAMS

6/06/2017  |   09:45 - 10:00   |  305A

Examining Riverine Dispersal of Zebra Mussels (Dreissena polymorpha) and the Invasion Risks to Texas Reservoirs and Streams The zebra mussel, Dreissena polymorpha, has recently spread into Central Texas waterways and research is needed to predict their spread and develop informed management strategies. We therefore examined riverine dispersal downstream of two lakes in Central Texas, where zebra mussels were first detected in 2013 and 2016, by monitoring dispersal of veligers, settlement, and growth of juveniles. Preliminary data suggest that settlement rates vary both spatially and temporally and may depend largely on variation in temperature and flow. While juvenile settlement was restricted to <13 rkm downstream of Lake Belton in 2015, they were found up to 55km downstream after prolonged periods of increased discharge in 2016. Veliger density and juvenile settlement was highest in spring and lowest in August likely due to temperature limitation. In addition, we are using an existing spatially-explicit ecological model that considers boater traffic and integrates it with physic-chemical measurements from Texas lakes to quantify the risk of establishment of zebra mussels in Texas.

Josi Robertson (Primary Presenter/Author), Texas State University, jjr131@txstate.edu;


Todd Swannack ( Co-Presenter/Co-Author), UNITED STATES ARMY ENGINEER RESEARCH AND DEVELOPMENT CENTER, Todd.M.Swannack@erdc.dren.mil;


Astrid Schwalb ( Co-Presenter/Co-Author), Texas State University, schwalb@txstate.edu;


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10:00 - 10:15: / 305A NEW INVASION RECORDS OF TREMATODE PARASITES CARRIED BY THE FRESHWATER INVASIVE SNAIL, MELANOIDES TUBERCULATA, IN FLORIDA, USA.

6/06/2017  |   10:00 - 10:15   |  305A

NEW INVASION RECORDS OF TREMATODE PARASITES CARRIED BY THE FRESHWATER INVASIVE SNAIL, MELANOIDES TUBERCULATA, IN FLORIDA, USA. Melanoides tuberculata is an aquatic snail of Asian origin that has invaded aquatic systems throughout the world, including Florida, USA. In their native range, these snails are intermediate hosts to at least 40 species of trematode parasites. However, no trematodes have been reported for M. tuberculata populations in Florida. The objective of this study was to establish if trematodes found in M. tuberculata occur in Florida and, if so, identify the worms using a molecular marker,18s rDNA. Snails were collected in September 2015 from a total of 13 sites across the state and eight populations were found to be infected with trematodes. Four of the snail populations were infected with Haplorchis tachui and three populations were infected with Paralecithodendrium longiformes, parasites of Asian origin not reported in the USA prior to this study. In addition, Centrocestus formosanus and Philophthalmus gralli (introduced in 2000 and 1971, respectively) were found in two populations. Results from this study emphasize the critical need for improved monitoring of invasive snails to detect, and possibly prevent, the spread of these invasive pathogens.

Lori Tolley-Jordan (Primary Presenter/Author), Jacksonville State University, ljordan@jsu.edu;


Jessica Wooten ( Co-Presenter/Co-Author), Centre College, jessica.wooten@centre.edu;


Michael Chadwick ( Co-Presenter/Co-Author), King's College London, michael.chadwick@kcl.ac.uk;


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