however, may indicate a preference for a transitional habitat 

 between the fine silty sand and cleaner sand in the New York Bight 

 apex. Ensis directus is a suspension feeder, TV. trivittatus is consid- 

 ered a scavenger, and P. ligni is a surface deposit feeder. 



Pratt (1973) included E. directus in his Middle Atlantic Bight 

 sand community, and Franz found both E. directus and N. trivitta- 

 tus to be characteristic of the medium sand assemblage in Long 

 Island Sound. However, N. trivittatus has also been recorded from 

 muddy sediments in Delaware Bay (Kinner et al. 1974). The sum- 

 mer distribution off. ligni places it in the ubiquitous species cate- 

 gory, however, its winter distribution is more limited. 



The diversity and mixing of previously defined faunal groups in 

 the deeper areas of the apex, especially the silty sand area, is, more 

 than anything else, probably a reflection of the heterogeneity of the 

 sediments there, disregarding local impacts of dumping. The sedi- 

 ments in the apex have been examined in great detail by Freeland et 

 al. (1976), showing a complex distribution of surficial sediment 

 types, including relic and anthropogenic deposits, as well as nor- 

 mal current and wave related distributions. 



Anthropogenic Influences 



The seabed of the New York Bight apex is influenced primarily 

 by continental shelf water of high salinity ( >32% ) and small tem- 

 perature fluctuations. Inshore areas are less stable and fall under the 

 influence of ocean waves and estuarine discharges, primarily from 

 the Hudson-Raritan Estuary. The estuarine discharges contain rela- 

 tively high levels of suspended sediment, organic material, and 

 nutrient and toxic pollutant loadings, all of which contribute to 

 altering the quality of the benthic environment, both inshore and in 

 the deeper offshore depositional basins of the apex. Waste dumping 

 also directly and indirectly impinges upon the benthos. The net 

 result of decades of using the Hudson-Raritan Estuary and the apex 

 as a repository fora variety of human wastes is that the apex benthic 

 environment, particularly the sediments in and around the dredge 

 spoil and sewage sludge dump sites, now contains a variety of con- 

 taminants occurring at levels that are stressful, lethal, or undesir- 

 able to many marine organisms. For example, high levels of five 

 heavy metals have been measured, in our survey, in both the dredg- 

 ing spoils and sewage sludge dump sites (Figs. 7-1 1). They are. in 

 general, correlated with sediments of highest organic content (Fig. 

 6). Metal concentrations in these areas are. in some cases, almost 

 50 times higher than those at apex stations away from the dump 

 sites and background levels in uncontaminated sands and silt (Table 

 5). 



Koons and Thomas ( 1979) also reported that total C, 5 . hydrocar- 

 bons are highest (3,600-6.500 ppm) in New York Bight areas 

 where harbor dredge spoil and sewage sludge disposal occurs. Lev- 

 els at the mouth of the Hudson-Raritan Estuary are reported as low 

 as 6-22 ppm, with concentrations of 82 and 86 ppm reported at two 

 locations approximately 80 km out on the mid-continental shelf. 



Table 5.— Concentrations of metals in sediment 

 unaffected b> waste dumping (ppm in dr\ sedi- 

 ments) (Carmodyct al. 1973). 



Cu Pb Ni Zn 



Elevated levels of heavy metals and hydrocarbons are well 

 known as being toxic to marine life. In high concentrations, they 

 are lethal, but even in sublethal concentrations they can cause path- 

 ological conditions, physiological disturbances, and deviations 

 from normal behavior. Larval stages are especially sensitive to 

 heavy metal toxicity and usually show increased abnormalities and 

 slow growth rates when exposed to such toxins (Sprague 1964; 

 Saunders and Sprague 1967; Shusterand Pringle 1968-'; Portmann 

 1970; Stirling 1970"; Calabrese 1972; Connor 1972; Calabrese et 

 al. 1973, 1977; Vernberg et al . 1973; Reish et al. 1974). 



The Christiaensen Basin and upper Hudson Shelf Valley benthic 

 environments are also subject to frequent seasonal dissolved oxy- 

 gen reductions to levels ( <2 ml/ liter) critical to many species of 

 marine organisms common in the New York Bight (Segar and Ber- 

 berian 1976; Steimle 1976; Thomas et al. 1976). The dissolved 

 oxygen reduction during the summer months is probably the result 

 of the higher oxygen demand of organic rich sediments and overly- 

 ing water in the central apex depression, coupled with the strong 

 seasonal thermocline which prevents reoxygenation of bottom 

 waters. 



Impacts to the benthic community are strongly indicated in our 

 data. Some abnormalities in faunal composition appear to be 

 directly related to the dumping of dredge spoils and sewage sludge. 

 Most of the species found in the upper Hudson Shelf Valley and 

 Christiaensen Basin exhibited some avoidance of one or both dump 

 sites (Tables 2-4) with a few exceptions: Capitella capitata was 

 collected almost exclusively at the sewage sludge dump site, and 

 Asabellides oculata occurred in greatest concentrations there; 

 Prionospio steenstrupi and Lumbrinehs tenuis showed high abun- 

 dances at the dredge spoil dump site (Figs. 2. 35, 39, 46, 55). 



The very low //"diversity values (Fig. 3). observed at stations 

 within and just outside both dump sites, indicate that the overall 

 benthic macroinvertebrate community structure in these areas has 

 also been altered. Low //"values are often associated with highly 

 stressed environments, where a few opportunistic or tolerant spe- 

 cies become abundant, in part because of reduced competition. 

 This results in a simple community, usually consisting of only a few 

 species (Sanders 1968). In this study, the sewage sludge dump site 

 was dominated by Capitella capitata, a highly opportunistic spe- 

 cies, and our data show the abundance distributions of only eight 

 species to indicate tolerance of sewage sludge, all are deposit feed- 

 ers. Thirteen species were observed to be tolerant of dredging 

 spoils. Of these, 1 1 are deposit feeders. 1 is a suspension feeder, 

 and 1 is a carnivore (Tables 2, 3). This predominance of deposit 

 feeders in and around the dump sites indicates that there may also 

 be a change in trophic composition of communities in these areas. 

 An examination of the feeding types of all species in Groups 1 and 

 2. i.e.. those which are ubiquitous or most often associated with 

 fine sand-silt sediments with generally high organic content, shows 

 a more equitable distribution of feeding types (Tables 2.3). 



Amphipod crustaceans, found to be important elements in most 

 faunal groups described in the Middle Atlantic Bight, are virtually 

 absent from coarse to medium silts and medium to high organic 

 content sediments in apex collections, an observation previously 

 reported by Pearce (1972). The marine silty sand group defined by 

 Pratt (1973), which intrudes up the Hudson Shelf Valley to the 



Sand) sediment of 



New York Bight 



Silty sediment of 

 Hudson Submarine 

 (Shelf) Vallej 



14 8 



20 



-'Shuster. C andB. Pringle. 1968. Effects of trace metals on estuarine molluscs. 

 In Proceedings of the 1st Mid-Atlantic Industrial Water Conference. Univ. Dela- 

 ware. CE-5. p. 285-304. 



—Stirling, E. 1970. Some observations on the response of the benthic bivalve Tel- 

 Una tenuis to pollutants. Proc. Int. Counc. Explor. Sea. CM. I970/E:!5. Fish. 

 Improvement Comm.. 6 p. 



50 



