JAN MAR MAY AiL SEP NOV 

 1963 



Figure 2.— Temperature trends of surface and 

 continental shelf off Louisiana, 



bottom waters over the 

 1963-65. 



eluded is the monthly discharge of fresh water from the 

 Mississippi River and other Louisiana rivers. Trends in 

 salinities were generally similar between years at the 

 respective depths, but differences did exist between 

 depths. At the 7-m stations, surface salinities generally 

 reflected near-bottom conditions with values ranging 

 from a low of 16.5%o to a high of 33.7%o. Annual 



JAN MAR MAY JUL SEP NOV 

 196J 



MAR MAY JUl SEP NOV JAN MAR MAY JUL SEP NOV JAN 

 19M 1965 



variations decreased with increasing depth and distance 

 offshore, with near-bottom salinities being virtually in- 

 variant at the 46- and 73-m depth zones. The effects and 

 extent of the seasonal discharge of fresh water from the 

 Mississippi River on offshore salinity values were readily 

 apparent over the entire continental shelf off Louisiana. 



Texas Offshore Waters 



Trends in monthly average temperatures of surface 

 and bottom waters at five depth zones are illustrated in 

 Figure 4. Similar trends were apparent each year, but as 

 in Louisiana waters, differences did occur with in- 

 creased distance offshore or total depth. Monthly 

 average temperatures of surface and bottom waters at 

 depths of 7 and 14 m were generally similar over the 3-yr 

 period, ranging from a low of about 10.5°C in February 

 1963 to a high of 30°C in September 1963. Temperature 

 ranges of both surface and bottom waters decreased off- 

 shore and with increasing depth. Also, differences 

 between surface and bottom measurements, when they 

 occurred, were more pronounced in the deep waters than 

 in the shallow waters. At depths of 28 m or greater, 

 average monthly values revealed that maximum bottom 

 temperatures occurred generally during a time when 

 temperatures of surface waters were decreasing. 



Yearly trends in monthly average salinity values of 

 surface and near-bottom waters off Texas (Fig. 5) were 

 more pronounced at station depths of 7 and 14 m than at 

 the deeper stations (28, 46, and 73 m). Seasonal 

 variations in salinities of surface and near-bottom waters 

 were generally similar out to a depth of 28 m, but beyond 

 that depth near-bottom salinities exhibited little 

 seasonal change. Marked decreases in salinity values, 

 either in surface and/or bottom waters, were related to 



Figure 3.— Salinity trends in surface and bottom waters over the con- 

 tinental shelf off Louisiana, 1963-65. 



Figure 4.— Temperature trends of surface and bottom waters over the 

 continental shelf off Texas. 1963-65. 



