water moves not only towards the west but also towards the coast, and, 

 due to multiple resuspension, the suspended materials remain in the 

 water column as opposed to being deposited on the shelf. Nearshore (~8 

 km) , the "shelf" turbid layer is joined by turbid water generated in the 

 high-energy littoral zone, and the combined turbid water mass is 

 transported westward. In the eastern part of the study area, much of 

 this material is trapped in the coastal marshes and mudflats of the 

 prograding Chenier Plain of southwestern Louisiana (Griffin 1979), but 

 the remnants can be detected beyond Galveston. 



The nature of the suspended material in seawater over the shelf is 

 of major importance. The inorganic fraction is virtually identical to 

 that of the Mississippi River (Griffin 1979). In addition to a high 

 sediment load, the Mississippi River and waters being discharged from 

 nearby estuaries in the eastern part of the study area were indicated by 

 Brent et al. (1979) to have high organic carbon loads. Based upon 

 Jacobs and Ewing (1969); Fredericks and Sackett (1970); and Harris and 

 Sackett (1970) over 50$ of the suspended material in shelf waters of the 

 northwestern gulf may be organic. The levels of organic carbon (7.8 to 

 13.1 mg/Z ) being discharged by the Mississippi River and estuaries in 

 the eastern part of the study area were of the magnitude necessary to 

 account for the observed carbon levels in gulf waters (Brent et al. 

 1979). 



Particulate organic carbon is only recently in the process of being 

 adequately characterized. Organic aggregates have historically been 

 collected by traditional methods (nets, pumps, bottles) and have been 

 characterized as small (25 to 100 urn). Results of in-situ observation 

 and careful collection have shown that organic particles form aggregates 

 ("marine snow") of much larger dimensions (millimeter to centimeter 

 range) which are easily disrupted, and seldom taken by traditional 

 methods (Campbell et al. 1980). These little-studied particles of 

 marine snow are potentially very significant centers of nutrient 

 regeneration and primary and secondary productivity. In addition, they 

 provide a prepackaged food source for larger oceanic consumers such as 

 herrings and spadefish. 



Temperature 



Water temperature over the Texas-Louisiana shelf fluctuates by 

 season, distance offshore, and/or latitude and depth. In surface 

 waters, particularly nearshore, seasonal variations in surface water 

 temperatures correspond well with coastal air temperatures (Figure 10). 

 Temple et al. (1977) showed that surface water temperatures over the 

 shelf vary little in summer, ranging from "29° to 31° C (Figure 11b). 

 However, during winter, surface isotherms nearly parallel the coastline 

 exhibiting a trend of increasing temperature with distance away from the 

 coast (Figure 11a). Depending upon the presence of a surface freshwater 

 layer, variation in temperature by depth is not markedly pronounced in 

 shallow shelf waters (a few degrees). However, in deeper shelf waters, 



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