Wednesday, May 25, 2016
13:30 - 15:00

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13:30 - 13:45: / 315 DOES INCREASING DENSITY STRESS FAVOR INVASIVE AMPHIPOD SPECIES IN CENTRAL EUROPEAN STREAMS? EVIDENCE FROM A LAB EXPERIMENT

5/25/2016  |   13:30 - 13:45   |  315

DOES INCREASING DENSITY STRESS FAVOR INVASIVE AMPHIPOD SPECIES IN CENTRAL EUROPEAN STREAMS? EVIDENCE FROM A LAB EXPERIMENT As globalization and climate change progress, invasive species emerge as serious threat to regional diversity worldwide. Increasing water scarcity combined with decreasing available space may promote invasion and density stress. This hypothesis was tested with the alien amphipod Echinogammarus berilloni, which displaces the native Gammarus pulex in Central European streams. Density effects in G. pulex populations were examined by simulating different levels of population density. Changes in locomotion, ingestion, glycogen content, and mortality were taken as criteria of potential stress response in G. pulex, in pure settings and combined with E. berilloni. In the pure G. pulex settings, high density level caused a reduction of activity and ingestion as well as a higher high glycogen content, indicating that G. pulex prefers moderate to high population densities. In the mixed settings, G. pulex evidenced an increased locomotion activity, reduced ingestion rate, higher mortality, and low glycogen content, revealing that the invasive E. berilloni exerts stress effects on the native G. pulex. Our findings contribute to explaining some mechanisms of the successful progression of E. berilloni and invasive species in general.

Elisabeth I. Meyer (Primary Presenter/Author), University of Münster, Institute for Evolution and Biodiversity, Department of Limnology, Hüfferstr. 1, D-48149 Münster, meyere@uni-muenster.de;


Jessica Rosolowski ( Co-Presenter/Co-Author), University of Münster, Institute for Evolution and Biodiversity, Department of Limnology, Hüfferstr. 1, D-48149 Münster, j_roso01@uni-muenster.de;


H. Wolfgang Riss ( Co-Presenter/Co-Author), University of Münster, Institute for Evolution and Biodiversity, Department of Limnology, Hüfferstr. 1, D-48149 Münster, riss@uni-muenster.de;


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13:45 - 14:00: / 315 MODELING LAKE INVASIONS BY CRYPTIC WATERMILFOIL TAXA AND THEIR ECO-EVOLUTIONARY RESPONSES TO MANAGEMENT

5/25/2016  |   13:45 - 14:00   |  315

MODELING LAKE INVASIONS BY CRYPTIC WATERMILFOIL TAXA AND THEIR ECO-EVOLUTIONARY RESPONSES TO MANAGEMENT Eurasian watermilfoil was introduced into North America in the late 1800s. It rapidly invaded many lakes with indigenous northern watermilfoil and has become one of the most heavily managed invasive aquatic plants in the U.S. In 2002, genetic identifications revealed that some of the plants previously identified as Eurasian watermilfoil were cryptic hybrids between Eurasian and northern watermilfoil. Laboratory and field evidence indicates that hybrids typically grow faster and are less sensitive to commonly-used herbicides than parental Eurasian watermilfoil. Recent evidence from a heavily managed lake in Michigan suggests that the ratio of hybrid to pure Eurasian watermilfoil has increased dramatically over the last four years. We present simulation results from an individual-based stochastic simulation model that incorporates known details of the life history and phenology of these taxa, allows immigration and competition, represents herbicide resistance as a multilocus quantitative trait, and allows plausible representation of common management methods. The results permit assessment of likely outcomes of invasion with or without management, and with management that does (with genetic identification) or does not distinguish between the cryptic invasive taxa.

James McNair (Primary Presenter/Author), Grand Valley State Univ. Annis Water Resources Institute, mcnairja@gvsu.edu;


Ryan Thum ( Co-Presenter/Co-Author), Montana State University, ryan.thum@montana.edu;


Syndell Parks ( Co-Presenter/Co-Author), Annis Water Resources Institute, syndell.parks@gmail.com;


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14:00 - 14:15: / 315 INFLUENCE OF SPECIFIC ELECTRICAL CONDUCTIVITY ON NATIVE AND INVASIVE SNAIL GROWTH RATE AND MORTALITY

5/25/2016  |   14:00 - 14:15   |  315

INFLUENCE OF SPECIFIC ELECTRICAL CONDUCTIVITY ON NATIVE AND INVASIVE SNAIL GROWTH RATE AND MORTALITY The invasive New Zealand mudsnail (Potamopyrgus antipodarum) tolerates a wide range of abiotic environmental conditions including temperature and salinity, but little is known on the tolerance of low specific electrical conductivity (EC) on this invasive snail and coexisting native snails. I assessed growth and mortality for two native snails and P. antipodarum by placing one of each snail into 500 mL cup with 400 mL of treatment solution. I created five treatment solutions with different EC levels (50, 100, 200, 400 and 800 µS/cm). P. antipodarum showed significant differences in growth with lower growth rates at lower EC levels. P. antipodarum also showed higher mortality in the 50 ?S/cm solution and lower mortality in the 400 and 800 ?S/cm solutions. No significant differences in growth rate or mortality were found for either native species. The lack of any significant differences in growth or mortality for the two native snails indicates higher tolerance of these snails to low EC which may enable these snails to reside in areas of the river that are less hospitable to P. antipodarum.

Michele Larson (Primary Presenter/Author), University of Wyoming, mlarso22@uwyo.edu;


Maurine Neiman ( Co-Presenter/Co-Author), University of Iowa, krist@uwyo.edu;


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14:15 - 14:30: / 315 THE ENIGMATIC MUD SNAIL, MARSTONIA LETSONI, INVADES LAKE ST. CLAIR.

5/25/2016  |   14:15 - 14:30   |  315

THE ENIGMATIC MUD SNAIL, MARSTONIA LETSONI, INVADES LAKE ST. CLAIR. Ecological effects within the Great Lakes ecosystems following the invasion of various exotic species, such as zebra and quagga mussels, goby, spiny waterflea, have been well documented over the past few decades. Environmental changes induced by these exotics (e.g. light intensity, sedimentation, and nutrient dynamics) consequently have resulted in changes in the abundance and distribution of many native Great Lake species (e.g. range expansions by amphipods, and range contractions by unionid mussels). We now report that a rare snail species native to U.S. tributaries of Lake Erie, Marstonia letsoni, has invaded and established a large population (2000/m2) in southern Lake St. Clair around 2010. It is possible that a recreational or fishing boat(s), likely stationed at a Huron River reservoir in Michigan, may have been the vector for this 3 mm tall snail as that is the location of the closest population. This may signal a new wave of invasions into the Great Lakes by species previously restricted to Great Lake tributaries as a result of environmental or ecological changes induced by exotic invaders.

Ronald Griffiths (Primary Presenter/Author), Oregon State University, Oregon Hatchery Research Center, Corvallis, OR 97331, ron.griffiths@oregonstate.edu;


Donald Schloesser ( Co-Presenter/Co-Author), Great Lakes Science Center, USGS, Ann Arbor, MI 48105, dschloesser@usgs.gov;


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14:30 - 14:45: / 315 PERSISTENT ECOSYSTEM CHANGES LINKED TO ZEBRA MUSSELS IN A SUBTROPICAL RESERVOIR

5/25/2016  |   14:30 - 14:45   |  315

PERSISTENT ECOSYSTEM CHANGES LINKED TO ZEBRA MUSSELS IN A SUBTROPICAL RESERVOIR Zebra mussels (Dreissena polymorpha) are an aquatic invasive species which colonized subtropical Lake Texoma (Oklahoma-Texas) in 2009. While zebra mussels are known for altering the systems they invade, our understanding of them primarily stems from research in temperate regions. As zebra mussels continue expanding into marginal habitats, their environmental impacts may be diminished, particularly with regular population die-offs. In 2011, we began a zebra mussel monitoring program in Lake Texoma and combined this with historic water quality data. Larval zebra mussel densities were linked to variations in temperature, with recruitment ceasing at peak water temperatures (~30°C) and large die-offs observed in 2011. Despite low zebra mussel abundances, we found a persistent increase in water clarity which coincided with mussel population establishment, but only in the arm of the lake which was heavily colonized by zebra mussels. This increase in water clarity could not be explained by changes in nutrients or zooplankton biomass, both of which remained constant. These findings indicate that subtropical water temperatures stress and suppress zebra mussel populations, yet they persist and still disrupt invaded ecosystems.

Thayer Hallidayschult (Primary Presenter/Author), University of Oklahoma, thayer@ou.edu;


Jessica Beyer ( Co-Presenter/Co-Author), University of Oklahoma, beyer@ou.edu;


K David Hambright ( Co-Presenter/Co-Author), University of Oklahoma, dhambright@ou.ed;


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14:45 - 15:00: / 315 EFFECTS OF CYANOBACTERIA ON QUAGGA MUSSEL (DREISSENA ROSTRIFORMIS BUGENSIS) REPRODUCTION

5/25/2016  |   14:45 - 15:00   |  315

EFFECTS OF CYANOBACTERIA ON QUAGGA MUSSEL (DREISSENA ROSTRIFORMIS BUGENSIS) REPRODUCTION Quagga mussels (Dreissena rostriformis bugensis) are highly fecund bivalves that have invaded North American and Western European waters. Nutritious algae may stimulate dreissenid spawning, while low quality food, such as bloom forming toxic cyanobacteria, could be a hindrance. The objective of this study was to determine the effects of cyanobacteria on quagga mussel spawning and fertilization. Spawning was quantified in a series of bioassays designed to determine if mussels released gametes in a solution containing cyanobacteria and a known chemical inducer (n=25). Fertilization was analyzed by combining eggs and sperm in individual vials containing various cyanobacteria cultures (n=5) and monitoring for zygote formation. For all assays, controls of artificial lake water and green algae were used. Two cyanobacteria cultures inhibited reproductive endpoints; spawning was suppressed by Aphanizomenon flos-aquae and fertilization rates decreased with exposure to Microcystis aeruginosa (p<0.05). Results from this study demonstrate an antagonistic relationship between cyanobacteria and quagga mussel reproduction. This information can be used to model mussel populations, and identification of a cyanobacterial chemical that impacts reproductive success may be useful in control programs.

Anna Boegehold (Primary Presenter/Author), Wayne State University, az1079@wayne.edu;


Karim Alame ( Co-Presenter/Co-Author), Wayne State University, ea4852@wayne.edu;


Nicholas Johnson ( Co-Presenter/Co-Author), USGS Great Lakes Science Center, njohnson@usgs.gov;


Donna Kashian ( Co-Presenter/Co-Author), Wayne State University, dkashian@wayne.edu;


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