This report describes the faunal assemblages of the deep-water benthic communities associated with the upper continental slope of the northern Gulf of Mexico, primarily in the area between Brownsville, Texas, and Cape San Blas, Florida.

This report presents data collected within a coastal strip near Newport Beach, California that is delineated by bottom depths ranging from 4 to 60 meters. Hydrographic data emphasize those factors that influence the distribution and abundance of organisms. Biological data include some observations on plankton abundance, and on both infaunal and epifaunal. Initiation of growth-rate studies on epifaunal species are described. Hydrographic observations include seasonal temperature-depth structures, oscillations of isotherms, salinity ranges, seasonal and vertical distribution of dissolved oxygen, and preliminary values for dissolved and particulate organic carbon. Some data are presented on water movements, including normal currents, surface-wave induced movements over submarine reefs, and inshore temperature flucutations associated with internal waves. (Author).

At the outset the report contains a discussion of several factors which indicate that deep ocean disposal of dredged material may need to be utilized much more extensively in the future than now. There follows a delineation and preliminary evaluation of the potential physical, chemical, and biological impacts that may occur from the disposal of dredged material in the deep ocean at and beyond the outer edge of the continental shelves of the United States and its possessions. A substantial part of the report is then devoted to the selection and description of oceanic areas (not sites) off eleven subdivisions or sectors of the U.S. coasts in which District Engineers or other Corps of Engineers officials may select specific disposal sites. The main body of the report is composed of two multipartite sections: Deep Ocean Disposal Perspectives, and Deep Ocean Disposal Environmental Considerations.

The report covers a detailed study of the morphology and ecological distribution of 11 species in 9 genera of gammarid amphipods collected offshore in the eastern Gulf of Mexico. It is based upon large series of specimens of all ages obtained during a study of biofouling conducted off Panama City, Florida. A new species is noted in the genus Microjassa (description to be published elsewhere), and a second species, in the genus Stenothoe, appears to be undescribed, but confirmation awaits further literature study in an obscure journal. Additional contributions of this study are insights into the range of morphological variation displayed by individuals of a single species from one locale, a delineation of the development of certain secondary sexual characteristics that have been a source of confusion in the literature, an outline of the development of gammarid populations on virgin surfaces, and the impact of certain physical factors on the life cycles of selected species. (Author).