The life history and ecology of the duskytail darter, Ethostoma (Catonotus) species, in Tennessee's Little River

An investigation of the life history and ecology of the little known duskytail darter, Etheostoma (Catonotus) species, was conducted in Tennessee's Little River. Adults and juveniles inhabited primarily shallow pools of cobbles and small boulders. Both sexes reached maturity at one year of age, and sexual dimorphism in breeding coloration was marked. Fecundity estimates based on counts of mature ova were low (19-44); however, after all mature ova are spawned, females may produce subsequent batches. Spawning occurred in late spring beneath slab-shaped cobbles. Both the male and female inverted, usually in a head-to-tail position, and eggs were clustered in a single layer on the underside of the stone. Males guarded nests of 23 to 200 eggs (average diameter = 2.9 mm) until they hatched (11-14 days at 18-27°C). Early growth was rapid, males grew faster than females, and the maximum age attained was 2+ years. A multiple census mark-recapture population estimate indicated that duskytail darters are abundant at the study site; the observed sex ratio was 1:1. The diet consisted mainly of chironomid larvae, minute crustaceans, and mayfly naiads. Darters were parasitized externally by leeches and internally by nematodes. Excessive siltation threatens the persistence of the Little River population.