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



609 



al., 1992). Winter flounder also rely al- 

 most entirely on small benthic 

 macrofauna for food; thus, variability in 

 predation and macrofaunal community 

 structure can have important conse- 

 quences for both the predator and its 

 benthic prey (Kurtz, 1975; Clements 

 and Livingston, 1982; Pihl et al., 1992). 

 This paper compares the diets of win- 

 ter flounder with the abundance of 

 benthic macrofauna at three stations in 

 the New York Bight apex variably af- 

 fected by sewage sludge, for evidence of 

 1) selective predation (preference or 

 avoidance), 2) variation in the propor- 

 tional consumption of benthic prey over 

 time, and 3) the manner in which preda- 

 tor-prey relationships influenced the 

 macrofauna with the cessation of sew- 

 age sludge disposal. 



Materials and methods 



7 4°00 



73°40' 



Cholera Bank 



40°20 - - 



D.plh In Ualot 

 I 



Winter flounder and benthic macro- 

 fauna collection methods, sample pro- 

 cessing, and primary data analyses for 

 this study have been described in de- 

 tail elsewhere (Reid et al. in press; 

 Steimle, in press). In brief, three stations, R2, NY6, 

 and NYU (Fig. 1), were sampled systematically from 

 July 1986 to September 1989 (Environmental Pro- 

 cesses Div. 1988). These stations represent a gradi- 

 ent of conditions related to sewage sludge disposal, 

 e.g. variable levels of total organic carbon (TOO and 

 chemical sediment contamination, such as chromium 

 (Cr), that changed to some degree after cessation of 

 disposal in December 1987 (Table 1). Station NY6 

 was the most sludge-affected area, with a markedly 

 altered benthic community characterized by a rela- 

 tively low species richness, low biomass, and high 

 levels of TOC sediment contaminant such as Cr 

 (Table 1). Station R2 was moderately affected by 

 sludge and was biologically enhanced; it showed rela- 

 tively high species richness and macrofaunal biom- 

 ass and moderate levels of sediment contamination 

 compared with NY6 (Table 1). Station NYU was the 

 least affected by sludge disposal, having relatively 

 high species richness but low macrofaunal biomass 

 and low levels of sediment contamination (Table 1). 

 All stations were about 30 m in depth and had simi- 

 lar sediment types (silty-fine sands) and hydro- 

 graphic characteristics (Table 1). 



Triplicate benthic macrofaunal samples were col- 

 lected monthly with a 0.1-m 2 Smith-Mclntyre grab 



Figure 1 



Location of stations and waste disposal sites in the New York Bight 

 apex where winter flounder, Pleuronectes americanus, and benthic 

 macrofauna were collected. 



sampler and sieved through a 0.5-mm mesh screen. 

 Materials retained were preserved in buffered for- 

 malin and later transferred to 70% ethanol. The 

 samples were sorted and organisms were identified 

 to the lowest possible taxon (usually species), 

 counted, and moist-weighed (Reid et al., in press). 

 Data from a total of 350 benthic macrofaunal samples 

 were available for analysis. 



Adult winter flounder were collected bimonthly 

 (additional collections were made in August) with a 

 small otter trawl at the same stations and during 

 the same week as the benthic grab sampling. Each 

 periodic trawl collection consisted of six daytime tows 

 of 0.5 km, deployed in an array across the center of 

 the station. Generally, at least 30 fish were collected 

 from each station per collection period. Stomach con- 

 tents were analyzed in the field or laboratory by us- 

 ing semi-quantitative, visual estimates of stomach 

 volume from comparison of stomach boluses with vari- 

 able-diameter, volume-calibrated cylinders. All identi- 

 fiable items in the stomachs were identified to the low- 

 est possible taxon and separated to visually estimate 

 their individual percent contribution to total stomach 

 volume (Langton et al., 1980; Steimle, in press). This 

 method provides reasonable results compared with 

 more labor intensive methods (Hyslop, 1980). 



