NOAA PROFESSIONAL PAPER 11 



increasingly frequent in eutrophic bays in Japan as well 

 as elsewhere in the world, anoxic conditions in bottom 

 waters can be expected to increase in severity concomi- 

 tantly. 



Mortalities of benthic organisms, associated with bot- 

 tom water of low oxygen content, occurred in the Gulf of 

 Trieste in the North Adriatic in 1974 (Fedra et al. 1976). 

 The authors reported scattered areas of decaying orga- 

 nisms in a region formerly characterized by stable benthic 

 populations. 



Oxygen depletion has occurred sporadically in Mobile 

 Bay, Ala., one of the largest estuaries of the Gulf of 

 Mexico. Stratification of the water column over a highly 

 organic bottom results in summer oxygen depletion, and 

 occasionally, because of winds, the water mass impinges 

 on beaches. Fish and invertebrates may be trapped in the 

 anoxic water near beaches — often in a disoriented or mor- 

 ibund condition — where they are taken in great numbers 

 by residents. This shoreline phenomenon is called a "ju- 

 bilee." Loesch (1960) reported 35 such occurrences be- 

 tween 1946 and 1956. but newspaper accounts go back to 

 the 19th century (the earliest is 1867). Oxygen depletion 

 in the bay could have occurred well before colonization 

 of the area in the 160Us, but human activities (particularly 

 dredging operations) have certainly intensified the situa- 

 tion. May (1973) reviewed the history of such events and 

 found no consistent increase in their frequency since 1946. 

 He carried out detailed oxygen determinations during a 

 jubilee in 1971 and found large areas of the bay with less 

 than 0.7 ml/1 dissolved oxygen in bottom water. Mortal- 

 ities of fish, crabs, and oysters were observed. 



SCOPE OF REPORT 



The investigations of the 1976 environmental event in 

 the Middle Atlantic Bight make this event one of the best- 

 documented examples of mass mortality in the sea. and 

 of the impacts of such events on resource and food-chain 

 species. It is a textbook-type study that focuses on solving 

 many interrelated problems. Scientific studies on oxygen 

 depletion in the Bight and adjacent coastal waters are 

 continuing, especially since the possibility of repetition of 

 the event at some level of intensity exists for future years. 



This report brings together the results of many studies 

 on the 1976 oxygen-depletion event. It examines the geo- 

 graphical extent of oxygen depletion and the environ- 

 mental conditions preceding and during the event, and 

 compares the 1976 conditions with historical information. 

 Particularly useful in this regard were NMFS resource 

 assessment data and the 1974-76 MESA current meter 

 and water column chemistry data. The latter data sets for 

 1976 were used in the form of a model to diagnose the 

 fluxes of dissolved oxygen into the affected region. An 



assessment is made of the causes, including the effects 

 human activities might have had. Impacts on fishery re- 

 sources and associated socioeconomic aspects are exam- 

 ined. Finally, monitoring and prediction of future events 

 are discussed. 



The terms "anoxia" and "anoxic" have been used to 

 describe the 1976 summer oxygen depletion in New York 

 Bight. Anoxic or anoxia refer to a condition where dis- 

 solved oxygen values are zero. Zero values did not occur 

 at all times everywhere in the Bight. The terms "anoxia" 

 and "anoxic" were conveniently used during the investi- 

 gations, and sometimes in this volume, in a less-precise 

 sense to indicate a deficiency of oxygen. 



To adequately consider the causes and the major geo- 

 graphic areas of impact, to more appropriately utilize the 

 existing data bases, and to provide continuity of analysis, 

 the Bight was subdivided into areal segments (fig 1-9). 

 These segments were selected to approximate distinctive 

 bathymetric features, such as the Hudson Shelf Valley 

 (H), major regions of oxygen depeltion (Jl), and the re- 

 gions most affected by human activities (A). For the most 

 part, analyses conform to these arbitrarily generated seg- 

 ments throughout the report — except where the idiosyn- 

 crasies of individual data sets require some other scheme. 



REFERENCES 



Beardsley. R. C Boicourt. W. C and Hansen, D. V., 1976, Physical 

 oceanography of the Middle Atlantic Bight, in M. G. Gross (ed.). 

 Middle Atlantic Continental Shelf and New York Bight. Amer. Soc. 

 Limnol. Oceanogr. Spec. Symp. 2:20-34. 



Bowman. M. J., and Wunderlich, L. D.. 1977. Hydrographic Properties. 

 MESA New York Bighl Alias Monogr. 1, New York Sea Grant 

 Institute. Albany. NY., 7S pp. 



Brongersma-Sanders. M.. 1947. On the desirability of a research into 

 certain phenomena in the region of upwelling water along the coast 

 of South West Africa. Proc. Kon Ned. Akad. Welensch. 

 50(6);659-665. 



Brongersma-Sanders, M.. 1957. Mass mortalities in the sea. in J. W. 

 Hedgepeth (ed.). Treatise on Marine Ecology and Paleoecology. 

 vol. 1, Geoi Soc. Amer. Mem. 67:941-1010, 



Deuser, W, G., 1975. Reducing environments, in J P Riley and G 

 Skirrow (eds.). Chemical Oceanography, vol, .'1, 2d ed,. Academic 

 Press, N.Y., 1-37. 



Faike, H., 1950. Das Fischsterben in der Bucht von Concepcion - Mit- 

 tlechile (Fish Mortality in the Bay of Concepcion - Middle Chile). 

 Senckenbergiana. (Frankfurt am Main, Germany), 31(1.2):57-77. 



Fedra, K. E., Olscher, M , Scherubel. C. Stachowitsch. M . and Wur- 

 zian. R. S,. 1976, On the ecology of a North Adriatic benthic com- 

 munity: distribution, standing crop, and composition of the macro- 

 benthos. Mar Biol. 38:129-145, 



Gordon, A, L,, Amos. A. F.. and Gerard, R, D,, 1976, New York Bight 

 water stratification, in M. G. Gross (ed). Middle Atlantic Conti- 

 nental Shelf and New York Bight, Amer. Soc Limnol. Oceanogr. 

 Spec. Symp., 2:45-57. 



Kalle, K., 1943. Die grosse Wasserumschichtung im Gotlandtief vom 

 Jahre 1933/34. Ann. Hydrogr. 71:142-146, 



Lettau. B.. Brower. W, A., Jr., and Ouayle, R. G.. 1976 Marme Cli- 

 matology. MESA New York Bighl Alias Monogr. 7, New York Sea 

 Grant Institute, Albany, NY. 239 pp. 



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