Comparative Nesting Biology of Two Sympatric Darters (Percidae: Etheostoma: Catonotus) in Headwater Streams of the Caney Fork River, Tennessee

Abstract

The Barrens Darter (Etheostoma forbesi) is a rare darter in subgenus Catonotus endemic to the Caney Fork River system in middle Tennessee. Hybridization with the closely related Fringed Darter (E. crossopterum) has been assumed as a risk to E. forbesi. To assess chronology and similarity of nesting habitat between these species, nests of both egg-clustering darters were observed through the spring nesting seasons in four streams during 2008 and 2009. Microhabitat variables associated with nests exhibited evidence of headwater specialization by E. forbesi that may isolate spawning populations from E. crossopterum. Etheostoma forbesi used nest rocks of smaller average dimensions and bottom surface area, and nested at shallower depths where water velocities were higher than nesting individuals of E. crossopterum. Nesting chronology and clutch sizes were similar between species, with spawning periods similar to those reported for other darter species in subgenus Catonotus and with clutch sizes up to 2,000 egg...