Distribution and ecology of Ergasilus cotti (Kellicott 1897) from mottled sculpin and rainbow darter

Session: Great Lakes Lower Trophic Level Community Dynamics (2)

Christopher Marshall, Cornell University, Department of Natural Resources, [email protected]
Joseph Connolly, Cornell Biological Field Station, [email protected]
Patrick Hudson, U.S. Geological Survey Great Lakes Science Center, [email protected]

Abstract

Parasitic copepods are well established in natural systems and provide a unique linkage between invertebrate zooplankton and animals they parasitize. Members of the Ergasilus genus are often referred to as generalist or specialists in their fish host associations. One such specialist of this group is Ergasilus cotti, first recognized as a species from populations of mottled sculpin (Cottus bairdi) collected in a creek near Westerville, Ohio in 1892. E. cotti was last observed in Ohio within the Alum Creek watershed on rainbow darter (Etheostoma caeruleum) in 1940. Mottled sculpin and rainbow darter are the only fish known to harbor E. cotti, which has developed a burrowing mode of attachment like the gill maggot, Salmincola. Using archived specimens of mottled sculpin and rainbow darter, we conducted a systematic survey to determine the presence or absence of E. cotti from creeks in OH, PA, and NY. This report also focused on providing an explanation for the observed distribution pattern. Currently, 630 mottled sculpin and 834 rainbow darters have been examined for E. cotti, yielding 5% and 0.01% prevalence rates respectively, with infected fish collected as early as 1922 and as recently as 2014. In total, 146 copepods have been recovered and preserved.