SUMMARY 



The Texas-Louisiana shelf ecosystem in the Gulf of Mexico is 

 described (1) in terms of its physiographic, oceanographic, and 

 biological characteristics and (2) as a recipient of oil and gas 

 development activities and effluents. The northeast sector of the 

 ecosystem is influenced by Mississippi River discharge, whereas 

 high-salinity Caribbean water affects the southwest sector. Soft-bottom 

 communities are prominent, characterized by economically valuable 

 penaeid shrimps. The coral reef communities, because of their 

 uniqueness and scarcity, are more important than would normally be 

 assumed. Pelagic communities are little known and harbor only a few 

 commercially valuable species. It is surmised that much of the primary 

 productivity from the pelagic community is used by the bottom 

 communities. 



Observed effects of oil and gas development activities and 

 effluents are described. Data from most field studies indicate that 

 direct effects are limited in space, but the effects over time are 

 unknown. One of the major problems has been separating effects of oil 

 and gas development-related activities and other man-induced variations 

 from natural changes. Particular concern is expressed relative to 

 increased organic loading of the system and the apparently related low 

 dissolved oxygen levels characteristic of some parts of the system 

 during warm seasons. It is recommended that future research be directed 

 towards defining key processes governing the ecosystem, with modeling 

 workshops serving as the focus for these research and monitoring 

 programs. 



IV 



