Figure 17. — Recording device measures continuously the 

 temperature of surface and bottom waters and bottom 

 sediments to provide information to help understand the 

 behavior of estuarine animals. 



Departmental report that included Fish and 

 Wildlife as a full partner in the Texas Basins 

 Project proposal. 



We are now working with the Estuarine 

 Technical Coordinating Committee of the Gulf 

 States Marine Fisheries Commission to de- 

 velop am estuarine atlas. The atlas will include 

 an inventory of basic descriptive andbiological 

 information for each estuary along our Gulf of 

 Mexico coastline. 



Charles R. Chapman, Program Leader 



ECOLOGY OF WESTERN GULF 

 ESTUARIES 



This project, as in former years, included 

 a wide range of activities. Routine hydrological 

 and biological sampling was continued through- 

 out Galveston estuary and adjacent marshes 

 to survey the environment amd abundance of 

 major species and to provide detailed infor- 

 mation on the estuarine phase of the brown 

 and white shrimp. 



The number of biological sampling locations 

 was reduced in January to include sites in a 

 nursery area complex in five of the six sub- 

 bays of the estuary. These sites include the 

 bordering marsh, controlling bayou system, 



bay beach (surf zone), near-shore waters, and 

 open bay. The high-salinity marshes and sub- 

 merged grass flats of West Bay are to be 

 added next year to complement the variety of 

 habitat types being studied. 



Hydrology 



Since 1963, the winter water temperatures 

 in the Galveston estuary have been turning 

 warmer (fig. 18). Temperatures during the 

 spring, however, have been getting cooler, as 

 have those in the fall. Following the normal 

 seasonal cycle, monthly mean water tempera- 

 ture was highest in September 1965 (29.2° C.) 

 and lowest in February 1966 (11.9° C). 



As in previous years, concentrations of total 

 nitrogen and phosphate were highest in the 

 upper bays of the estuary and declined Gulf- 

 ward (fig. 19). Although seasonal trends are 

 apparent and values are highest in winter, 

 considerable fluctuation is evident. The ex- 

 tremely high levels of nitrogen and phosphate, 

 particularly in the upper bays, are probably 

 c aused by industrial waste and domestic sewage 

 that enter the estuary from the San Jacinto 

 River via the upper Houston Ship Chamnel. 



OTTOM TEMPERATURE 



Figure 18.— Seasonal trends In water temperature In the 

 Galveston estuary. 



SPRItJO 'summer' fall I winter 'si>RlN0'suM«ie«' FALL I WINTER ' SRRINO 



Figure 19.— Influence of pollution from the upper Houston 

 Ship Channel (mouth of San Jacinto River) on upper and 

 lower Galveston Bays as Indicated by seasonal trends 

 In total nitrogen and total phosphate. 



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