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Figure 3. — Average species diversities (//') of benthic invertebrates. 



Figure 4.— Average numbers of benthic invertebrates per square meter. 



In the Bight apex, surface salinities during January and February 

 increase to the annual maximum of >34% . Bottom salinities are 

 > 34% over most of the apex. Salinities begin to slowly decrease 

 in March as river discharges increase. The spring (April, May) 

 river runoff and penetration of slope water tend to increase vertical 

 salinity gradients, however, these gradients vary greatly, even over 

 a few days. Summer (June. July. August) surface salinities range 

 from about 25-27% near the apex mouth to about 30-3 1% at the 

 southeast corner. Bottom salinities range from 27-29%, along the 

 Sandy Hook-Rockaway transect to 30-32%„ at the outer edge of the 

 apex. The seasonal minima occur in June. Vertical mixing during 

 autumn (September. October) reduces vertical salinity gradients 

 and leads to a steady increase in surface salinity, often as large as 

 0.8% between July and October. Surface and subsurface salinities 

 continue to increase through early winter (November. December) 

 until the winter maxima are attained in January. 



A large range between summer and winter surface temperatures 

 is characteristic of the Bight. River runoff into the apex is low in 

 winter when strong vertical mixing unstratifies the water column 

 and temperatures drop to their annual minimum, often <2°C in 

 mid-January. Bottom temperatures during November through Feb- 

 ruary tend to be slightly higher than surface temperatures because 

 vertical mixing does not keep pace with rapid surface cooling. Win- 

 ter minima persist into late February or early March. During April, 

 surface temperatures warm to =7°-8°C, with bottom tempera- 

 tures usually remaining at <4°C except near the coast. A thermo- 

 cline appears in May and intensifies during June when surface 



Figure?. 



-Mean grain size to units) of sediments averaged over five quarterly 

 cruises (August 1973-September 1974). 



