CHAPTER 12 



Additional samples were collected during June and July 

 1977 and July 1978 to examine recolonization and long- 

 term impacts. Only preliminary data are available tor 

 these samples. 



DIVER OBSERVATIONS 



Benthic fauna was one of the first groups of organisms 

 observed to be affected by the oxygen depletion. Initial 

 clues to a developing problem came during the weekend 

 of June 27. 1976. Sport divers visiting wrecks off central 

 New Jersey observed lobsters (Homanis amencanus) and 

 rock crabs {Cancer sp.) congregated on the highest parts 

 of wrecks, indicative of stressful but not yet lethal con- 

 ditions at the bottom of the water column, below the 20- 

 m-deep thermocline. They also observed surf clams (Spi- 

 sula solidissima) lying on their sides on the sediment sur- 

 face, also considered an indication of stress — for instance, 

 hypoxia (Savage 1976). Initial reports of actual marine 

 mortalities came during the July 4, 1976, weekend (Bul- 

 lock 1976; E. Geer, American Littoral Society, personal 



communication). Sport divers reported many dead fish 

 and invertebrates on or near wrecks and other diving spots 

 off the north-central New Jersey coast in a zone extending 

 from Long Branch to Barnegat Inlet and from about 5 to 

 40 km offshore. The invertebrate mortalities consisted 

 mostly of rock crabs, lobsters, blue mussels (Mytihis ed- 

 ulis), and starfish (Asterias forbesi). Some lobsters were 

 very sluggish, lying exposed, out of their shelters, with 

 some sharing holes or dens. As the area of oxygen deple- 

 tion increased, sport divers reported mortalities on wrecks 

 as far south as Atlantic City by July 17. Divers reported 

 mortalities off the central New Jersey coast throughout 

 the summer. 



In September, sport divers reported partial recovery 

 and recolonization at some affected wrecks northeast of 

 Manasquan Inlet. The recolonizers were mostly finfish, 

 but a few rock crabs and lobsters were also found, where 

 previously all were dead or had left the area. 



During March 1977. NOAA divers reexamined an area 

 near the center of the 1976 anoxia zone, southeast of 

 Manasquan Inlet. They observed dense aggregations of 

 the tube-dwelling polychaete, Asabellides oculata (fig. 

 12-2). 





'A 





FIGURE 12-2.— Dense clumps of Asabellides oculala tubes located by NOAA divers off Manasquan Inlet during March 1977. Tubes are 5 to 10 

 cm long. (Photograph courtesy of E. Geer, American Littoral Society, Highlands, N.J.) 



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