A habitat on the brink? An assessment of the status of fishless lakes in Maine

Presentation not available.

Emily Gaenzle Schilling¹(student), Cynthia S. Loftin², Alex D. Huryn³, K.E. DeGoosh⁴

1. Department of Wildlife Ecology, University of Maine, 5755 Nutting Hall, Orono, ME 04469-5755; emily.schilling@umit.maine.edu; 207-581-1340
2. USGS-Maine Cooperative Fish and Wildlife Research Unit, University of Maine, Orono, ME; Cyndy_Loftin@apollo.umenfa.maine.edu; 207-581-1340
3. Department of Biological Sciences, University of Alabama, Box 870206, Tuscaloosa, AL 35487; huryn@bama.ua.edu; 205-348-4136
4. New England Interstate Water Pollution Control Commission, RI Department of Environmental Management, Providence, RI; katie.degoosh@dem.ri.gov; 401-222-4700

Fish introductions have resulted in a loss of fishless lakes across the state. This is of concern because fishless lakes provide critical habitat for many taxa. To assess the status of fishless lakes in Maine, we: 1) characterized their invertebrate communities, 2) assessed the effects of introducing fish to these communities, 3) identified species indicating fish absence to enable rapid identification of fishless lakes, and 4) used subfossils of indicator invertebrates from sediment cores to determine if currently stocked lakes were historically fishless. Invertebrates were sampled from 51 lakes (22 fishless; 29 contained fish, 7 of which were historically fishless). Our results showed that the species composition of Notonectidae, Chaoboridae, Dytiscidae, and Gyrinidae differed significantly between lakes with and without fish, with some taxa occurring only in fishless lakes. Subfossil analysis revealed that Chaoborus americanus is an indicator of historical as well as current fish absence. Finally, some taxa (Aeshnidae, Corixidae, Dytiscidae, Gyrinidae, Notonectidae) were most abundant in fishless lakes. Our results highlight the unique characteristics of fishless lake invertebrate communities and provide a tool to verify historical fish absence in lakes that have been stocked.