SFS Annual Meeting

5/20/2019  |   09:00 - 09:15   |  251 DE

BUSH TUCKER AND BIODIVERSITY: WEED MANAGEMENT ON THE FLOODPLAINS OF KAKADU NATIONAL PARK Invasive alien species are a major driver of global biodiversity loss. Constrained conservation budgets demand that threat abatement strategies must take into account the heterogeneity of areas in need of protection, such as significant ecological and cultural sites, as well as the competing values, preferences and objectives of stakeholders. We used an interdisciplinary team to assess the threat that invasive alien grasses pose to both environmental and Indigenous cultural values on the floodplains of Kakadu; a co- managed, World Heritage-inscribed national park. We evaluated costed management scenarios that sought to simultaneously conserve biodiversity and bush tucker. We found that there was a greater initial cost to protect both bush tucker and biodiversity sites comparted with just protecting biodiversity, but the ongoing costs were similar. This was the first study to apply strategic foresight to weed management planning in a realistic, culturally complex setting and it provides Traditional Owners and park managers with a basis for improved floodplain weed management.

Michael Douglas (Primary Presenter/Author), University of Western Australia & Charles Darwin University, michael.douglas@uwa.edu.au;


Sue Jackson (Co-Presenter/Co-Author), Australian Rivers Institute and Griffith University, sue.jackson@griffith.edu.au;


Vanessa Adams (Co-Presenter/Co-Author), University of Tasmania, vm.adams@utas.edu.au;


Kelly Scheepers (Co-Presenter/Co-Author), Kelly Scheepers, kellyjscheepers@gmail.com;


Johnathan Kool (Co-Presenter/Co-Author), Consultant, johnathan.kool@ga.gov.au;


Samantha Setterfield (Co-Presenter/Co-Author), University of Western Australia and Charles Darwin University, samantha.setterfield@uwa.edu.au;


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5/20/2019  |   09:15 - 09:30   |  251 DE

OPTIMIZING INVASIVE CRAYFISH TRAPPING METHODS, CASE STUDY OF PROCAMBARUS CLARKII Recent crayfish invasions have exposed the lack of proven methods for eradicating populations and preventing spread. We have identified an isolated population of the invasive red swamp crayfish (Procambarus clarkii) in the Chicago River (Illinois, USA) that could spread into Lake Michigan and other Laurentian Great Lakes. The only available method for controlling crayfish populations in lotic ecosystems is intensive trapping, but this is expensive and little is known about how to optimize efforts. We report on experiments to determine the approach that yields highest catch per unit effort (CPUE; number of crayfish captured per trap cleared). First, we determined the optimal number of nights to leave traps in the water. Traps emptied after one night gave a CPUE of 0.71, and this increased for traps left for two (1.11) and three (1.61) nights. Next, we examined CPUE for five different baits (P. clarkii, herring, dog food, hot dog, beef liver). Hot dogs gave a CPUE significantly higher than other baits (Tukeys, p = <0.01). These results show that simple changes to trapping programs can increase CPUE and hopefully lead to more effective control of invasive crayfishes.

Colette Copic (Primary Presenter/Author), Loyola University Chicago, ccopic@luc.edu;


Rachel Egly (Co-Presenter/Co-Author), Loyola University Chicago, regly@luc.edu;


Erin O'Shaughnessey (Co-Presenter/Co-Author), Loyola University Chicago, eoshaughnessey@luc.edu;


Reuben Keller (Co-Presenter/Co-Author), Loyola University Chicago, rkeller1@luc.edu;


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5/20/2019  |   09:30 - 09:45   |  251 DE

DO RESOURCE SUBSIDIES FROM INVASIVE RIPARIAN TREES FACILITATE NON-NATIVE FISH IN THE UPPER COLORADO RIVER BASIN? Species invasion can disrupt linkages between terrestrial and aquatic ecosystems by altering timing and magnitude of cross-ecosystem subsidies. Novel subsidies, or subsidies from non-native species, may disproportionately benefit invasive consumers in recipient ecosystems. Here we test the hypothesis that resource subsidies from an invasive Russian olive tree (Elaganus agustafolia) directly facilitate non-native channel catfish (Ictalurus punctatus) in the San Juan River (NM/UT, USA). Large fluxes of carbohydrate-rich olives drop into the river in late summer and autumn and are heavily consumed (up to 80% of diet seasonally) by catfish but not native fishes. Bioenergetic modeling and experimental trials suggest that olives contribute little to catfish growth and lipid accumulation but may provide metabolic energy. We conclude that olives likely provide an energy subsidy to catfish that may be particularly important during periods of low prey availability and high metabolic demand. Consumption of RO fruit may decrease predation pressure on native fishes and alleviate competition for other food resources. Our results illustrate how riparian invasions may facilitate aquatic consumers through cross-ecosystem subsidies.

Brandon K. Peoples (Co-Presenter/Co-Author), Clemson University, peoples@clemson.edu;


Reuben Goforth (Co-Presenter/Co-Author), Purdue University, rgoforth@purdue.edu;


Christopher Cheek (Primary Presenter/Author), Purdue University, Christopher.Cheek@sdstate.edu;


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5/20/2019  |   09:45 - 10:00   |  251 DE

USING EDNA TO DETECT AND MONITOR AQUATIC INVASIVE PLANTS Environmental DNA is a rapidly developing technology for use in aquatic invasive species management, however, there are substantial unknowns with respect to application in monitoring programs. We conducted experimental and field-based sampling to test detectability of two invasive aquatic plants (Egeria densa and Myriophyllym spicatum) using eDNA, and evaluate feasibility of this method to supplement current monitoring approaches. In 2017, a mesocosm experiment was conducted over a 10-week period to assess changes in eDNA detection as a function of plant growth stage and biomass. In 2018, eDNA samples were collected from western Washington lakes with varying species abundances, and a subset of lakes were sampled throughout the year to test temporal variability in detection. In mesocosm experiments, we found that detection was less reliable while plants were actively growing, and improved as a function of both increased biomass and senescence. This was supported in field sampling results, which resulted in higher detections during peak biomass and senescence periods. However, detection was unsuccessful except at the highest levels of plant abundance in both experiments and the field, indicating challenges in using eDNA as a substitute for traditional monitoring.

Lauren Kuehne (Primary Presenter/Author), University of Washington, lauren.kuehne@gmail.com;


Carl Ostberg (Co-Presenter/Co-Author), US Geological Survey, costberg@usgs.gov;


Dorothy Chase (Co-Presenter/Co-Author), US Geological Survey, dchase@usgs.gov;


Julian Olden (Co-Presenter/Co-Author), University of Washington, olden@uw.edu;


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5/20/2019  |   10:00 - 10:15   |  251 DE

LONG-TERM POPULATION DYNAMICS OF DREISSENID MUSSELS IN THE HUDSON RIVER ESTUARY A 27-year record of dreissenid (zebra and quagga mussel) populations in the freshwater tidal Hudson River shows dramatic (i.e., 5- to 10-fold) interannual variation in population density, individual body size, biomass, and population filtration rate. This variation is a result of both cyclic and long-term change. Persistent cycling appears to be a result of competitive dominance or cannibalism by strong year classes, which appeared every 2-5 years. The frequency of these strong year-classes has increased, presumably as a result of increased mortality in recent years. Long-term changes include (1) the appearance of the quagga mussel in 2008, which however still constitutes only 1-10% of all dreissenids, (2) increases in (predatory?) mortality rate of adult mussels, (3) decreases in body size, and (4) decreases in population filtration rates. In contrast, we could detect no long-term changes in dreissenid densities or habitat use (i.e., spread onto soft sediments). We found little evidence for environmental control of population dynamics, though mortality may be higher in hot summers. It appears that long-term dynamics of dreissenid populations in the Hudson are driven chiefly by negative density dependence and changes in mortality rates.

David Strayer (Primary Presenter/Author), Cary Institute of Ecosystem Studies, strayerd@caryinstitute.org;


Stephen Hamilton (Co-Presenter/Co-Author), Cary Institute of Ecosystem Studies, hamilton@caryinstitute.org;


Heather Malcom (Co-Presenter/Co-Author), Cary Institute of Ecosystem Studies, malcomh@caryinstitute.org;


Christopher Solomon (Co-Presenter/Co-Author), Cary Institute of Ecosystem Studies, solomonc@caryinstitute.org ;


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5/20/2019  |   10:15 - 10:30   |  251 DE

CHARACTERIZING NATURAL BARRIERS TO NON-NATIVE STREAM FAUNA IN HAWAII Waterfalls, caused by the abrupt changes of elevation in streams, are natural barriers that influence the distribution and dispersion of aquatic species. While resulting habitat fragmentation has contributed to species specialization, the steep elevation changes are also considered barriers that inhibit passage of non-native species upstream. In Hawai?i, it is assumed that non-native species are unable to surpass waterfall barriers, yet they are present above some waterfalls, possibly facilitated by human introduction. In this study, we used a landscape approach to identify likely human introductions and examine the ability of non-native stream fauna to bypass waterfalls. We found that when a given catchment has a population density higher than 4.24 people/km2 or when road length density is greater than 0.01 km/km2 in a stream catchment, the presence of non-native species in the stream was likely due to human introduction. After filtering human facilitated introduction, we found that 12 out of the examined 14 taxa were absent upstream of waterfalls, indicative of their inability to traverse waterfalls. Without human interference, waterfalls can be considered effective barriers to non-native species and can be instrumental in supporting exotic species eradication and control strategies.

Yin-Phan Tsang (Primary Presenter/Author), Department of Natural Resources and Environmental Management, University of Hawaii, Manoa, tsangy@hawaii.edu;


Brendan Martin (Co-Presenter/Co-Author), University of Hawaii at Manoa, btmartin@hawaii.edu ;


Ralph Tingley (Co-Presenter/Co-Author), Missouri Cooperative Fish and Wildlife Research Unit, tingleyr@msu.edu;


Hannah Clilverd (Co-Presenter/Co-Author), Center for Ecology and Hydrology, hanilv@ceh.ac.uk;


Dana Infante (Co-Presenter/Co-Author), Department of Fisheries and Wildlife, Michigan State University, infanted@msu.edu;


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