102 



water, as in Laguna Madre, and create an inverse estuarine system. 

 Sunlight beating down on shallow embayments may raise temperatures 

 so hi^h that use of the estuarine waters for cooling may be seriously 

 impaired. 



Table IV. 1.8 summarizes ocean and river water quality in each of the 

 estuarine regions. Ocean water quality itself varies in different areas 

 off the coast, generally reflecting ocean currents and climate as dis- 

 cussed earlier. Ocean temperatures reflect not only the variation in lat- 

 itude, but also the temperature differences of the cold and warm 

 currents around the coast. The temperature difference north and south 

 of Cape Hatteras is particularly striking, because the Gulf Stream and 

 Labrador Current water each dominate on one side of the Gape. 



Nearshore ocean surface salinities are strongly influenced by river 

 runoff and local precipitation. The effects of the Mississippi on the 

 Gulf of Mexico are shown in figure IV.1.29. Less dramatic but none- 

 theless significant, are the effects of the Hudson on the Atlantic and of 

 the Columbia on the Pacific. 



FIGURE IV.1.29 SURFACE SALINITY DISTRIBUTION AROUND 

 THE MISSISSIPPI DELTA 



28< 



Surface Salinity Distribution (%o} 

 November 9-16, 1966 



S=30-34%» 



91* W 90' 89» 



SOURCE 'Bureau of Commercial Fisheries, Galveston, Texas 



88« 



