The influence of shell dredging in San Antonio Bay, Texas, on the Aransas National Wildlife Refuge and surrounding bays was investigated by a team from Texas A&M University in order to prepare an environmental impact statement for the U.S. Army, Corps of Engineers. More than 60 scientists and technicians from the Wildlife and Fisheries, Biology, Meteorology, Geology, and Oceanography Departments were involved. The data indicate that shell dredging has no significant, irreversible effects on the ecosystem of the bay.

In addition to sedimentologic and subbottom studies, the geologists undertook most of the circulation, flushing, remote sensing, foraminiferal, chemical studies. Some also were involved in investigating economics, reef silting, and dredge discharge.

San Antonio Bay has an average depth of 4 ft and contains numerous large and small reefs. As a result of the bay's shallowness, the circulation and flushing are controlled primarily by wind and river discharge, and therefore patterns of these aspects are erratic. Nevertheless, certain consistent patterns can be distinguished on the bay bottom as well as in the shallow subsurface. Heavy-mineral distributions and clay-mineral studies present complementary information. The distribution of modern reefs differs little from that of buried reefs. These distributions and several borings reveal the gross topography of the buried Pleistocene surface.

It is clear that in such an environmental impact study, a thorough investigation of the geologic, physical, and economic aspects is equally as important as understanding the biologic aspects of a coastal ecosystem.

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