Oxygen Depletion and Associated Benthic Mortalities 

 in New York Bight, 1976 



Chapter 6. Bottom Oxygen and Stratification in 



1976 and Previous Years 



Reed S. Armstrong' 



CONTENTS 



Page 



137 Introduction 



137 Climatological Conditions 



139 Oxygen Cycle and Stratification 



142 Stratircation and Dissolved 



Oxygen in 1976 



143 Regional Aspects 



147 Previous Benthic Mortalities 



147 Summary 



148 Acknowledgments 

 148 References 



' Atlantic Environmental Group, National Marine 

 Fisheries Service, NOAA, Narragansett, Rl 02882 



INTRODUCTION 



The areal extent of the 1976 anoxic condition implies 

 that broad-scale, climatic events may have contributed to 

 the depletion of dissolved oxygen (D.O.). Although the 

 area of depleted oxygen extended widely over the conti- 

 nental shelf off New Jersey, it apparently did not develop 

 to the north, off Long Island, nor to the south, off the 

 Delmarva Peninsula. Therefore, if unusual climatic con- 

 ditions did contribute to the anoxia and resulting benthic 

 mortalities, then other distinct differences among these 

 three regions of the Middle Atlantic Bight should be ap- 

 parent. 



To examine the impact that climatic events in the marine 

 environment may have had on the generation of anoxic 

 conditions, historical and climatological data were com- 

 piled for comparison with conditions observed in 1976. 

 Included were monthly mean air and sea-surface temper- 

 ature records and oceanographic data from the National 

 Climatic Center (NCC), National Oceanographic Data 

 Center (NODC), National Ocean Survey (NOS), and 

 National Weather Service (NWS) of the National Oceanic 

 and Atmospheric Administration (NOAA), and river dis- 

 charge records from the U.S. Geological Survey. Data 

 from oceanographic stations occupied in the area in 1976 

 were provided by NOAA National Marine Fisheries Serv- 

 ice's (NMFS) Sandy Hook Laboratory, and NOAA En- 

 vironmental Research Laboratories' Atlantic Oceano- 

 graphic and Meteorological Laboratories (AOML). 



CLIMATOLOGICAL CONDITIONS 



Springtime conditions in 1976 began developing 1 to 2 

 months earlier than normal (ch. 3). Monthly mean air 



137 



