from several sources. Phytoplankton productivity of the apex, for instance, averages 

 about three times higher than that of the outer Bight (Malone et al., 1979). 



The predominantly sandy and muddy sand sediments of the Bight are particularly 

 hospitable environments for four groups of larger benthic invertebrates: bivalve 

 molluscs, annelid worms, the echinoids (sea urchins and sand dollars), and 

 crustacean shellfish. Both the total numbers of benthic invertebrates and their total 

 weight decrease markedly from nearshore to the edge of the continental shelf. 

 Benthic biomass depends as well upon sediment type, increasing by a factor of 

 almost 20 from sand-gravel (94 g/m ) to silty sand (1,800 g m") (Wigley and 

 Theroux, 1976). 



As a consequence of long-term carbon and toxicant loadings to the inner Bight, an 

 area of sediments greater than 240 km" (93 m~) in the apex is enriched with carbon, 

 toxic metals, petroleum hydrocarbons, and synthetic organic compounds. These 

 same sediments typically contain depauperate benthic communities, with very high 

 standing crops of a very few species. Organic enrichment of fine-grained sediments 

 seems to be the major factor altering the preexisting competitive balance among 

 many species whose feeding strategies differ. The high standing stocks and reduced 

 species diversity observed in parts of the apex may be caused by this mechanism. 

 Additional stresses that may contribute to these effects include the production of 

 toxic sulfide ions and resuspension of other toxicants that tend to exclude predators 

 and reduce cropping. Until recently, observations of benthic community alterations 

 had been restricted primarily to the benthic macrofauna. However, recent studies 

 have shown parallel disturbances in meiofaunal species assemblages of affected 

 sediments (Tietjen, 1980). 



Fish populations of the Bight are dominated by migratory species. Temperature is 

 a strong stimulus for the migration of most coastal fishes, and temperature changes 

 also stimulate spawning. The abundance of individual fish species within the Bight 

 has commonly fluctuated by a factor of four in the past 25 years. While the major 

 cause of year to year fluctuations is climatic variability, sport and commercial fishing 

 caused serious declines in nearly all commercially important species from I960 to the 

 mid-1970s. From 1967 to 1974 the total biomass of finfish caught by bottom trawls 

 declined by more than 50 percent in the region from Cape Cod to Cape Hatteras. 

 Sport fishing has also increased rapidly. Recreational catches are estimated to be 

 about as large or larger than domestic commercial catches for striped bass, bluefish, 

 weakfish, summer flounder, winter flounder, black sea bass, cod, and mackerel. 

 Since 1974 more restrictions have been imposed to reduce commercial fishing levels, 

 and fish stocks as a whole have increased (Grosslein and Azarovitz, 198 1). The most 

 significant finfishes in the Bight for commercial and sport fishing demands include 

 cod, summer flounder, bluefish, striped bass, Atlantic mackerel, winter flounder, 

 black sea bass, and weakfish. 



Shellfish are also important commercial and recreational resources. Based upon 

 sampling in 1976, the estimated biomass of ocean quahogs was 2,450,000 t of meats; 

 surf clam meats were estimated at 875,000 t. Sea scallops are another major offshore 

 resource for which biomass estimates are not available. 



The food webs built up from plant material and detritus lead to continual 

 replenishment of harvestable fish and shellfish resources of the Bight. However, 

 within the Hudson-Raritan Estuary several fish and shellfish species no longer grow 

 and reproduce adequately to sustain exploitation. Even those species maintaining 

 harvestable densities within the estuary contain PCB concentrations that approach 

 or exceed FDA limits and cannot be harvested commercially. Filter feeding shellfish 

 within the estuary and the inner Bight contain concentrations of coliform bacteria 

 that prohibit commercial exploitation. 



The massive discharges of particulate material from the New York metropolitan 

 region both limit the primary productivity within the estuary and stimulate the 

 detrivores that feed upon organic particles. However, the limited information 

 available indicates that the rates of carbon degradation within the estuary have not 



50 



