Pollution indicator species of macrobenthos in a coastal lagoon

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Abstract
Life history differences and effects of physicochemical changes on macrobenthos of coastal lagoons were studied for 2 yr at one site in the sewage-polluted, moderately enriched Sykes Creek and a comparison site in the less polluted Banana River, Florida, USA. Monthly and bimonthly quantitative sediment samples for faunal analyses were taken from the natural substratum, and recolonization of defaunated sediments set out at 4 different times in 1 yr was monitored concurrently. The top 4 numerical dominants in natural substratum samples from Sykes Creek, i.e., the indicator species, were: Corophium ellisi, Haploscoloplos foliosus, Capitella capitata, Anomalocardia auberiana. Based on recolonization experients all 4 were identified as opportunistic. The top 2 numerical dominants in the Creek (C. ellisi, H. foliosus) also relied on their abilities to exploit food and/or space. Banana River benthos contained a greater relative abundance of equilibrium species and fewer opportunistic species compared to Sykes Creek, suggesting that there has been a shift toward a life history strategy of opportunism species in the enriched area. With a lag shift of 2 mo. dissolved O and temperature from the Creek were strongly correlated with macrobenthic density. Drastic declines involving most species present were observed in early summer in 1978 and 1979 coinciding (no 2 mo. lag) with O/temperature extremes of < 2.5 mg l-1/29.degree. C. Pollution indicator species were as intolerant of O/temperature extremes as nonindicator species. Numerical dominance of the indicator species in shallow water and sand sediments in Sykes Creek can likely be explained by some combination of superior abilities related to quick invasion and exploitation of food and/or space, competitive interactions could be important. Investigation of the indicator concept was posed as one of the best ways to determine the effects of organic pollution on benthos.