Abstract. — a 39-month study 



of the effects of cessation of sew- 

 age sludge disposal in the New York 

 Bight apex on the diets of certain 

 fishes and on the benthic macro- 

 faunal community provided an op- 

 portunity to examine predator-prey 

 relationships of winter flounder, 

 Pleuronectes americanus, one of the 

 common predators in the area. 

 Benthic macrofauna and winter 

 flounder were collected monthly 

 and bimonthly, respectively, from 

 July 1986 through September 1989 

 at three sites in the Bight apex that 

 are variably influenced by sewage 

 sludge. There were limited changes 

 in winter flounder diets and abun- 

 dance of dominant benthic macro- 

 faunal species following cessation 

 of sewage sludge disposal. The com- 

 parison of volumetric contribution 

 of common prey in flounder stom- 

 achs to potential-prey abundance 

 in benthic samples suggested sev- 

 eral relationships. These included 

 evidence of preferential predation 

 on the polychaete Pherusa affinis; 

 this selective preference may be 

 associated with its high caloric con- 

 tent as well as with its average 

 high biomass density. Other com- 

 mon prey, primarily polychaetes 

 but including an anthozoan, were 

 also preyed upon in proportions 

 greater than their abundance in 

 the environment. Some moderately 

 abundant potential prey, such as 

 the small near-surface-dwelling 

 mollusc Nucula proximo and the 

 ribbon worm Cerebratulus lacteus 

 were not commonly preyed upon 

 suggesting they were unavailable 

 as prey or were avoided by winter 

 flounder. Corresponding fluctua- 

 tions in abundances and predation 

 of the pollution-tolerant polychaete 

 Capitella sp. and the pollution-sen- 

 sitive amphipod Unciola irrorata 

 suggested a proportional consump- 

 tion relationship in association 

 with sludge disposal and its cessa- 

 tion. 



Predator-prey relationships of winter 

 flounder, Pleuronectes americanus, 

 in the New York Bight apex 



Frank W. Steimle 

 Dorothy Jeffress 

 Stephen A. Fromm 

 Robert N. Reid 

 Joseph J. Vitaliano 

 Ann Frame 



Sandy Hook Laboratory, Northeast Fisheries Science Center 

 National Marine Fisheries Service. NOAA 

 Highlands. New Jersey 07732 



Manuscript accepted 30 December 1993. 

 Fishery Bulletin 92:608-619 (1994). 



608 



Predator diets provide information 

 on sources of prey, predominant 

 prey types, levels of particular prey 

 use and availability, and prey pref- 

 erence or avoidance, when com- 

 pared with the availability of poten- 

 tial prey in the environment (Lev- 

 ings, 1974; Diehl, 1992). For preda- 

 tory fish such as winter flounder, 

 Pleuronectes americanus, this infor- 

 mation increases our understand- 

 ing of prey selection, based on evi- 

 dence of prey preference or avoid- 

 ance, and how selective predation 

 can affect or be affected by prey pop- 

 ulation dynamics. 



In studies of aquatic environmen- 

 tal health, benthic macrofaunal di- 

 versity and certain indicator species 

 are often used as response vari- 

 ables. Monitoring predator diets 

 during such studies can aid in de- 

 termining how predation can func- 

 tion as a confounding factor in in- 

 terpreting macrofaunal change as 

 solely the product of altered abiotic 

 factors. Monitoring diets can also 

 indicate how benthic species abun- 

 dance and the overall community 

 structure can be affected by preda- 

 tion. Predation studies can also aid 

 in estimating the effect of benthic 

 macrofaunal changes (natural or 

 anthropogenic) on predator-prey 



relationships (i.e. loss of a season- 

 ally or energetically important prey) 

 or be used to define potential con- 

 taminant uptake pathways (Cle- 

 ments and Livingston, 1982; Gen- 

 dron, 1987; Schindler, 1987). 



Studies of the linkage between 

 prey abundance and predation by 

 marine fish are scarce, especially 

 studies based on samples taken over 

 an extended period of time or dur- 

 ing an environmental change. An 

 opportunity to examine predator- 

 prey relationships was provided by 

 the availability of the results of a 

 comprehensive 39-month study of 

 the effects of sewage sludge disposal 

 abatement in the New York Bight 

 apex (the coastal area at the mouth 

 of New York Harbor). This study 

 included monitoring the diets of sev- 

 eral common fishes and large deca- 

 pod crustaceans, the abundance of 

 benthic macrofauna, as well as 

 other biological and environmental 

 variables (Environmental Processes 

 Div., 1988). 



The winter flounder, Pleuronectes 

 americanus Walbaum (Robins et al., 

 1991 ) is an abundant demersal fish 

 in the New York Bight apex. It was 

 the third most important contribu- 

 tor (KM) to the total fish biomass 

 collected during the study (Wilk et 



