The effects of suspended sediment on the reproductive success of the tricolor shiner: implications for conservation in Cyprinella (Cyprinidae)

Noel M. Burkhead and Howard L. Jelks
USGS, Biological Resources Division, 7920 NW 71st Street, Gainesville, FL 32653. (352.378-8181, ex 324; gax 378-4956; noel_burkhead@usgs.gov

Excessive sedimentation is an underappreciated, pervasive stressor to aquatic life and habitats. Suspended sediment causes multiple negative effects in fishes and degradation of benthic habitats, particularly in streams. The effects of suspended sediment on the reproductive success in the tricolor shiner (Cyprinella trichroistia) were experimentally examined. The experiment was based on an ANOVA model where the response variables were numbers of propagules spawned and relative proportions of developmental stages. Each of the three trials had four replicates of four treatments: 0(control), 100, 300, and 600 mg/1 suspended clay fines (<=63µ). Suspended sediment significantly reduced the incidence of spawning, numbers of propagules spawned, and delayed the initiation of spawning behavior. The effects were inferred to be a generalized reduction of behavioral interactions due to obfuscation of visual stimuli. Spawning behavior in Cyprinella is remarkably uniform with males exhibiting sexual dimorphism and dichromatism, and engaging in ritualistic displays that are components of visual communication. With chronic exposure during spawning seasons, it is probable that excessive sedimentation prevents adequate reproduction and contributes to range fragmentation and imperilment in sensitive Cyprinella.