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PCR Tracking of Predation on Non-native Species in Lake Erie

Lake Erie’s ecology is disrupted by aquatic invasive species (AIS), such as the round goby (Neogobius melanostomus) tubenose goby (Proterorhinus semilunaris). The impact of the tubenose goby on the Great Lakes ecosystem is relatively unstudied. Our current studies focus on discovering which species of fish prey upon these invasive gobies. We use polymerase chain reaction (PCR) to detect specific DNA samples of this aquatic invasive species in the feces of piscivorous fish of Lake Erie.  Identification of DNA for the gobies must be specific and accurate for our method to be successful. We optimized primers to be species-specific to segments of cytochrome oxidase I (COI) from the fish. We have demonstrated the specificity of our primer sets. Our assay is also sensitive; we can detect DNA samples at a concentration below 10ng/mL. The Qiagen Tissue Kit is the most effective method we use to extract DNA. This molecular approach offers advantages compared to traditional gut content analyses because collection of feces does not harm the fish and it allows for community partners such as anglers to participate in our assessment by collecting fecal samples. Involvement of community partners would allow us to map where and when piscivorous fish recently consumed round and tubenose gobies.  We’ve found round goby DNA in the feces of 5 fish representing 3 different species. Most of our collecting was focused in the vicinity of Presque Isle Bay. While we can identify tubenose goby DNA in feces of lab-reared fish, we have yet to identify tubenose goby DNA in the feces of wild piscivorous fish. This makes it difficult to draw any conclusions about predation on tubenose gobies – it indicates that native, piscivorous fish may prey on tubenose gobies at a very low level but allows no conclusions about the causes of this minimal predation. Do native fish avoid the tubenose goby or is the population so small that we haven’t captured the moment where a fish has preyed on them. Seining efforts and this data suggests that the population of tubenose goby is considerably lower than the round goby population.

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