CHAPTER I 



extremes; and biological causes include algal blooms, dis- 

 ease, predation, and toxins. 



Scientific literature has reported mass mortalities due 

 to many of the above causes. Probably the most complete 

 report is by Brongersma-Sanders ( 1957), who exhaustively 

 reviewed all known mass mortalities in the sea. Other 

 reviews include those of Sindermann (1970. 1976). 



In the 1976 New York Bight event, bottom water oxygen 

 values were zero and hydrogen sulfide was formed in the 

 central New Jersey coastal area off Atlantic City. Divers 

 consistently reported a brownish flocculent layer beneath 

 the thermocline in much of the affected area. Oxygen 

 depletion persisted until October when lower surface tem- 

 peratures and mixing broke down the pycnocline and grad- 

 ually reoxygenated the bottom water. 



Fish, lobsters, and mollusks were found dead. Seden- 

 tary forms — surf clams, ocean quahogs, and other benthic 

 animals — had the greatest mortalities. From almost con- 

 tinuous surveys, scientists estimated that more than half 

 the surf clam population off the central New Jersey coast — 

 over 100,000 metric tons (t) — had been destroyed by Oc- 

 tober, with significant but smaller mortalities of ocean 

 quahogs and sea scallops. Lobster catches declined by 

 almost 50 percent during the period. Consequently, the 

 Federal Government declared the New Jersey coast a re- 

 source disaster area in November. 



The occurrence of mass mortalities in New York Bight 

 is particularly significant considering the heavy stress that 

 humans have placed on these coastal waters and the pend- 

 ing efforts to manage this marine resource more effec- 

 tively. It is known that people and their activities con- 

 tribute to the Bight, mostly through the Hudson-Raritan 

 estuarine system, large quantities of carbon and nutrients 

 that would not otherwise get there. Some people consid- 

 ered ocean dumping, particularly sewage sludge dumping 

 within 22 km of the coast, to have been the cause of the 

 oxygen depletion and resultant mass mortalities. 



If efficient and effective resource management is to be 

 adopted, then it is essential to understand the complex 

 responses of the marine ecosystem to natural and man- 

 induced stimuli. Given this understanding, prediction of 

 such events can be improved. If the contaminants from 

 human activities are found to play a significant role, man- 

 agement strategies can be adopted to lessen the likelihood 

 of such catastrophic events in the future. 



This professional paper examines the extensive data 

 base available in the context of the above issues. The 

 scope of the problem proved so broad and the sources of 

 data so dispersed that many scientists and organizations 

 contributed to the analysis of the causes, extent, duration, 

 and effects of the anoxic condition. 



A number of research groups — Federal, State, univer- 

 sity, and industry — participated actively in data acquisi- 

 tion and analysis. The National Science Foundation con- 



vened a workshop on the problem in October 1976. and 

 the participating research groups organized their own 

 workshops in November 1976. Proceedings of these work- 

 shops have been published (Sharp 1976; National Marine 

 Fisheries Service 1977). 



Initial indications from these efforts were that severe 

 oxygen depletion developed in the bottom waters in re- 

 sponse to a combination of anomalous environmental 

 events superimposed on a coastal area characterized by 

 reduced dissolved oxygen in an average summer. 



Atmospheric events included high February-March air 

 temperatures with abnormally high river runoff in Feb- 

 ruary and March, which was before the usual annual spring 

 peak in April; reduction of storm activity during spring 

 and summer to less than half the 25-year average; and a 

 period of 4 to 6 weeks in June-July with unusually per- 

 sistent south to southwest winds. 



Oceanic events included early (February-March) warm- 

 ing of surface waters; early development of the halocline; 

 and a massive bloom of the dinoflagellate Ceniliiim tripos 

 over much of the Middle Atlantic Bight (continental shelf 

 from Montauk Point, N.Y., to Cape Hatteras, N.C.). but 

 concentrated in New York Bight. The bloom began in 

 February, persisted at least until July, and was concen- 

 trated at and just below the pycnocline. 



Oxygenation in the ocean occurs in the surface layers 

 (photic zone) through air-sea interaction and photosyn- 

 thesis and through advective processes. Thus, oxygen re- 

 plenishment of deep waters often comes only from water 

 that has been in contact with the surface layers. With this 

 in mind, a hypothesis was developed that included the 

 following components: 1) superimposition of high oxygen 

 demand from a declining phytoplankton (Ceratiiim tripos) 

 bloom on an area (New York Bight) already characterized 

 by reduced dissolved oxygen in an average summer; 2) 

 sealing off of this organically rich oxygen-demanding 

 water mass early in spring by the early onset of a pyc- 

 nocline; and 3) disruption of the usual spatial pattern of 

 currents such that the bulk of the oxygen-demanding ma- 

 terial is concentrated off the New Jersey coast. These 

 elements supply the ingredients of disaster to marine an- 

 imals. 



PHYSICAL DESCRIPTION OF THE BIGHT 



New York Bight is a 39,000-km- sector of the Middle 

 Atlantic continental shelf between Montauk Point, N.Y., 

 and Cape May, N.J., approximately 180 km wide from 

 the Hudson-Raritan estuary to the shelf edge. Depths 

 range between 30 and 60 m over much of the Bight, with 

 the inner shelf off New Jersey being somewhat shoaler 

 than that off Long Island. The shelf break generally occurs 

 at a depth of 140 m. The most prominent topographic 



