written by Kyle Glenn, graduate student
The onset of winter generally concludes the field season for many studies. However, graduate student and GLC center research assistant Kyle Glenn is ready to sample the freezing streams in search of the round goby. Discovering winter presence or absence is only one facet of Kyle’s year-round sampling effort but it may help bridge data gaps regarding goby migratory and feeding behavior. Kyle and his advisor, Dr. Chris Pennuto, are compiling years of data on winter presence/absence and diet composition of round gobies across streams of Western New York, including Kyle’s Undergraduate Summer Research Fellowship project research.
One method used to indicate the value of a particular prey item is to compare how many captured fish have eaten that prey with the total number of that prey eaten among all the fish collected. In general, prey that are eaten by most of the fish in a population and prey that are eaten in large numbers are deemed valuable to the population. It is then possible to compare multiple locations or different times of year to determine if the same prey items are important across the range of conditions experienced by round gobies. Preliminary results suggest chironomid midges are a valuable winter prey item across all locations where fish have been captured in winter. This differs slightly from past investigations of summer diets, where more prey types, in addition to midges, provide significant food resources.
Next up for Kyle is an investigation on whether round goby foraging behavior has any impact on stream drift. Stream drift is increased invertebrate activity that occurs at night when they enter the water column to either evade predators or search for more resources. Kyle plans to answer the question “do non-native, benthic-feeding fishes impact stream drift?” Gobies are thought to impact invertebrate communities through the consumption of prey, but some of Kyle’s preliminary results point to gobies altering drifting invertebrate behavior. Seeing how these alterations to drift extend beyond the stream shoreline and potentially impacts riparian spiders is a gap in research that remains to be answered.
Kyle recently presented his preliminary findings on drift differences among streams with and without round gobies at the NY Chapter of the American Fisheries Society meeting. He showed that certain taxa were more common in the drift when gobies were present, suggesting that those taxa were avoiding round gobies. He also showed that riparian spiders were less abundant at locations harboring round gobies, suggesting that these non-native fish may facilitate a reduction in the emergence of adult insects. These early results will require further assessment and make up the bulk of Kyle’s thesis work. His ability to collect the data needed for his thesis has been made possible by funds from the Graduate Student Association, a Stevenson Award from the Great Lakes Center, and the use of a field vehicle from the GLC.
Image caption: Kyle Glenn sampling Lake Erie tributaries for round gobies in March.
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