Octocorals in the Gulf of Mexico - Their Taxonomy and Distribution with remarks on their Paleontology
Giammona, Charles Peter, Jr.
MetadataShow full item record
The distribution of octocorals in the Gulf of Mexico is reviewed in this paper. The taxonomy, ecology, and paleontology of this group from along the Texas Gulf coast are emphasized. A brief taxonomic description of 59 species, mostly from the western Gulf, is given. All are illustrated in photographic plates. Two new varieties (Leptogorgia virgulata var. ctenella and Thesea grandiflora var. gardensi) and two new species (Anthomastus sp. and Muricea sp.) are described. The distribution of Gulf octocoral families and genera representing 622 specimens are plotted on 35 separate charts. They represent 22 families, 50 genera, and 152 species. The biotic assemblages and ecology of octocorals along the Texas outer continental shelf were studied using a submersible and conventional diving techniques. Abiotic environmental factors, particularly turbidity from the nepheloid layer, affect small-scale distributions, abundance, and diversity of the hard-bank communities on the Texas continental shelf. Biotic factors such as dispersal, predation, competition, and behavior reactions may also influence distribution patterns. Ecological factors such as temperature, substrate type, and depth probably have the most influence on large-scale distribution patterns in the Gulf. The Gulf is divided into 61 geographic subunits, and the species collected from each subunit are listed. A classification method of numerical analysis is used to determine octocoral distribution patterns within the Gulf of Mexico. On that basis, six octocoral provinces are defined: 1) sub-tropical Gulf, 2) western Florida, 3) northern Gulf, 4) western Gulf, 5) southeast Mexican coast, and 6) central Gulf. Thirty-five fossil octocoral stem fragments and holdfasts were collected from the Stone City Formation (Claiborne group, middle Eocene) near College Station, Texas. The fossils belong to the order Gorgonacea. They represent the fifth reported occurrence of octocorals in the Tertiary strata of the Texas Gulf coast and the first reported occurrence of the family Gorgoniidae. A new genus and species, Gorgonites banmiti, is proposed for this material. The geologic history and distribution patterns of Gulf fossil octocorals are discusses in relation to recent distribution patterns.