EFFECTS OF SUSPENDED, DIESEL-CONTAMINATED SEDIMENT ON FEEDING RATE INTHE DARTER GOBY, GOBIONELLUS-BOLEOSOMA (TELEOSTEI, GOBIIDAE)

The darter goby, Gobionellus boleosoma, a bottom-feeding gobiid fish, was used as a meiofaunal predator in laboratory experiments designed t o determine the effect of suspended diesel-contaminated sediment on fe eding rate, Estuarine sediments are sinks for hydrophobic contaminants , and contaminant exposure from suspended sediment seems likely in est uarine mudflats. The darter goby is a small estuarine fish that lives in shallow mudflats surrounding Spartina alterniflora marshes, feeding primarily on meio- and small macrofauna, We first showed that darter gobies are effective feeders on suspended meiobenthic copepods and tha t this feeding was not affected by suspended sediment loads as high as 2000 mg l(-1). Harpacticoid copepods then were offered as ad libitum prey to gobies after exposure to either contaminated or non-contaminat ed sediments via a single turbidity event 24 h prior to feeding, Based on gut content analysis, goby standard length influenced feeding rate as larger gobies ingested more meiobenthic copepods in the l-h experi ment. Diesel-fuel contamination reduced feeding rate by 50-100% in all but the lowest dosage examined; ANCOVA (with length as a co-variate) indicated that feeding rate after exposure to suspended sediments abov e 200 mg PAH kg dry sediment(-1) was significantly reduced relative to uncontaminated controls: No feeding occurred at 687 mg PAH kg dry sed iment(-1) (the greatest concentration tested), The proportion of non-f eeding fishes increased with increasing levels of contamination, and a n additional experiment suggested that the source of contamination was associated with direct contact with contaminated sediment rather than exposure to water previously associated with contaminated sediment. ( C) 1997 Elsevier Science Ltd.