Expansion of a Banded Killifish Fundulus diaphanus Population into Benthic Nearshore Waters of Lake Michigan around Calumet Harbor

Abstract

Banded Killifish Fundulus diaphanus are considered a nearshore species closely associated with emergent or submergent vegetation in shallow calm waters. This species is commonly collected in nearshore waters of the Laurentian Great Lakes, usually along margins of coastal wetlands, beaches, drowned river mouth lakes, and slow-moving streams. However, in recent years (2015–2018) Banded Killifish have commonly been collected along the exposed, industrialized nearshore waters of Lake Michigan around the Calumet Harbor area (Chicago, IL). Individual specimens have been collected up to 2.8 km from shore and in depths up to 9.8 m in open waters of Lake Michigan. Capture of this species along hardened shoreline habitat, including rip-rap and steep drop-offs is also highly unusual for this small, littoral species and is not documented in the available literature. These observations provide an extreme example of habitat use by this littoral species and broadens our understanding of their habitat in nearshore waters of the Laurentian Great Lakes.