A distribution study of deep-sea macrobenthos collected from the western Gulf of Mexico

Abstract

One of Texas A&M University's more detailed oceanographic cruises was that of R/V ALAMINOS 69A11, basically biological in scope but also including hydrographic, sediment coring, and bottom photography stations. Dredge sampling of the deep-sea macrobenthos was accomplished by means of the benthic skimmer in three western Gulf regions (Galveston, Tampico, and Vera Cruz). This distribution study of the benthic macrofauna revealed five faunal zones that were differentiated on a bathymetric basis. These have been designated as Outer Continental Shelf, Upper Continental Slope, Lower Continental Slope, Continental Rise, and Abyssal Plain. Faunal breaks revealed by the similarity dendrogram, constructed from individual station data, support the proposed faunal zones. Recurrent patterns of species occurrence were used to formulate benthic assemblage, showing expected species and their relative abundance, for specific depths within the faunal zones. Data concerning species occurrence within the three geographic regions of the western Gulf under consideration were not sufficient to warrant extension of existing biotic provinces into the deep sea. Analysis of sea-floor photographs revealed at least 87 living organisms, various plant fragments, sediment composition and texture, and other ichnological phenomena. Several selected photographs have been included. A phylogenetic list of all benthic species, including author and date, collected as living specimens at one or more of the dredge stations has been compiled. Slight modification and combination of the suprageneric taxonomy used by earlier authors was utilized.