Steimle et al.: Predator-prey relationships of Pleuronectes americanus 



613 



Cessation of sewage sludge disposal 



The change in abundance of two benthic species, the 

 polychaete Capitella sp. and the amphipod U. 



Station R2 



100 

 90 

 80 

 70 

 60 

 50 

 40 

 30 

 20 

 10 

 



f^S 



7 8 9101112 12 3 4 5 6 7 8 9101112 12 3 4 5 6 7 8 9101112 12 3 4 5 6 

 ! 86 I 87 I 88 I 89 



collection period 



irrorata, was associated with the cessation of sludge 

 disposal (Reid et al., in press). These changes were 

 also reflected in the occurrence of these two prey in 

 winter flounder stomachs. When sludge disposal 

 ended in 1987, the abundance of the stress- 

 tolerant Capitella sp. declined and so did its 

 occurrence in stomachs at station NY6 (Fig 

 4). For the more stress-sensitive U. irrorata, 

 predation was also generally associated with 

 abundance at two stations (Fig. 5). At sta- 

 tion NY6, where the effect of sludge disposal 

 was greatest, the abatement of sludge dis- 

 posal was accompanied by a seasonally vary- 

 ing increase in the abundance of this amphi- 

 pod and a corresponding increase in the fre- 

 quency of occurrence in winter flounder stom- 

 achs (Fig. 5). 



89 



; 



stomach volume 



benthic biomass 



Station NY6 



7 8 9101112 12 3 4 5 6 7 8 9101112 12 3 4 5 6 7 8 9101112 123456789 



86 I 87 I 88 I 89 



collection period 



stomach volume 



benthic biomass 



Station NY11 



7 8 9101112 12 3 4 5 6 7 8 9101112 12 3 4 5 6 7 8 9101112 123456789 

 86 I 87 I 88 I 89 I 



collection period 



stomach volume 



benthic biomass 



Discussion 



Diet spectrum and dominance 



The spectrum of prey and dominant prey taxa 

 consumed by winter flounder in the New York 

 Bight apex (Table 2) is similar to that re- 

 ported in other winter flounder diet studies 

 (Wells et al., 1973; Hacunda, 1981; Langton 

 and Bowman, 1981; Bharadwaj, 1988; Steimle 

 and Terranova, 1991). Winter flounder diet 

 studies in estuaries and to the north also re- 

 port the dominance of similar prey taxa 

 (Tyler, 1972; Wells et al., 1973; Worobec, 

 1982). With the possible exception of Capi- 

 tella sp., dominant prey are usually macro- 

 scopic, supporting Keats' (1990) hypothe- 

 sis that winter flounder show a preference for 

 the largest available prey that can be consumed. 



Predation patterns 



The results of this study provide evidence 

 that some prey species are consumed prefer- 

 entially, but this was not temporally or spa- 



Figure 2 



Trends in the percent contribution of the burrow- 

 ing anemone Ceriantheopsis americanus to total 

 stomach volume of winter flounder, Pleuronectes 

 americanus, compared to the anemone's percent- 

 age of the total benthic macrofaunal biomass at 

 three sites in the New York Bight apex variably 

 affected by sewage sludge disposal. Disposal 

 gradually abated during 1987 and ceased by De- 

 cember 1987. 



