Stable isotope patterns of benthic organisms from the Great Lakes region indicate variable dietary overlap ofDiporeiaspp. and dreissenid mussels

Abstract

Competition between native and invasive species may bring about a suite of ecological and evolutionary outcomes, including local extirpations. In the Laurentian Great Lakes, competition for food may explain the dramatic decline of Diporeia spp. amphipods following the introduction of dreissenid mussels. This hypothesis has not been confirmed, in part because dreissenids and Diporeia appear to co-exist and flourish in other systems, including the Finger Lakes of New York. We used carbon, nitrogen, hydrogen, and oxygen stable isotope ratios to examine resource use by Diporeia from three spatially distinct populations (Lake Michigan, Lake Superior, and Cayuga Lake), dreissenids from areas where they co-occur with Diporeia (Lake Michigan and Cayuga Lake), and Diporeia from Lake Michigan collected before and after dreissenid invasion . Our results suggest that dreissenids may affect resource use by Diporeia in areas of co-occurrence, but the extent to which those effects are positive or negative is unclear. Terrestrial inputs may provide an important subsidy for Diporeia populations in small systems but may not be substantial enough in the Great Lakes to ensure that both taxa thrive.

Expanding the Isotopic Toolbox: Applications of Hydrogen and Oxygen Stable Isotope Ratios to Food Web Studies

“…We also explore some of the other unique applications of H isotopes in food webs, which include determining the resources that support aquacultured and invasive species (Cole and Solomon, 2012;Evans, 2012;Foley et al, 2014;Emery et al, in press), how stream food webs respond to fire (Cooper et al, 2015), interactions between hydrology and turbidity in river ecosystems (Roach and Winemiller, 2015), and detecting contributions of methanotrophic biomass (Deines et al, 2009). …”

“…Similarly, both zebra mussels and another invasive species, the quagga mussel (Dreissena rostriformis bugensis) in the Great Lakes, derived more of their food from autochothonous sources compared to the native mussel (Diporieia spp.) (Foley et al, 2014). Evans (2012) compared the percent autochthony vs. allochthony in native and invasive lamprey species from rivers in Michigan and Ohio, and found that terrestrial vegetation was more dominant in the diet of the native species in most cases.…”

Trophic overlap in mobulid rays: insights from stable isotope analysis

“…Researchers are increasingly using stable isotope analysis as a tool for inferring the trophic ecology of animals, providing insight into trophic niche separation (Cherel et al 2007, Plass-Johnson et al 2013, trophic overlap (Foley et al 2014, Jackson et al 2016, diet composition (Semmens et al 2009), and diet shifts (Ben-David et al 1997, MacNeil et al 2005. Stable isotopes of carbon (δ 13 C) and nitrogen (δ 15 N) are 2 of the most commonly used isotopes in ecological studies, as they can provide information on feeding locations and prey types due to predictable changes in δ 13 C across habitats (France 1995) and increases in δ 15 N at higher trophic levels (Owens 1987).…”

DNA metabarcoding assays reveal a diverse prey assemblage for Mobula rays in the Bohol Sea, Philippines

“…Molecular techniques can reveal if these organisms are a component of ray diets. Furthermore, understanding dietary overlap between co‐occurring species can provide insight into their resource use (Foley et al, ), and if conducted over multiple years, can reveal if these patterns change over time (Hardy et al, ).…”

“…Dietary information can be directly applied to help reduce incidental catch in protected species, for example, by changing the type of bait used when fishing (Watson, Epperly, Shah, & Foster, 2005). Multispecies feeding studies examine dietary overlap (Foley, Bowen, Nalepa, Sepulveda, & Hook, 2014;Jackson et al, 2016;Stewart et al, 2017) and trophic niche partitioning (Cherel, Hobson, Guinet, & Vanpe, 2007), which have further implications for the competition of prey among sympatric species. Ecology, conservation biology, and fisheries rely on food web characterization as an initial step in ecosystem understanding.…”