A taxonomic and ecological study of selected benthonic gammarid crustaceans from the northeastern Gulf of Mexico

Abstract

From May 1964 until May 1966 a fouling study was conducted off the coast of Panama City, Florida. In the course of this investigation samples of organisms were taken from floats exposed at various controlled depths for various controlled time periods at three different stations. Many of these samples yielded large numbers of certain species of gammaridean Amphipoda in various sizes and stages of development. Most previous studies of this group have been limited by small samples of a few specimens taken from widely separated regions. The fouling study material offered an unusual opportunity to study the development of selected gammarid species. The taxonomic portion of this dissertation centers upon the morphological development of Microjassa macrocoxa and Stenothoe gallensis with comments on Ampithoe ranondi, Elasmopus rapax, Melila fresneli, Jassa falcata, Photis pugnator, and Podocerus brasiliensis. A new species of Microjassa and an unidentified species of Stenothoe are discussed. It is suggested that topotypic and developmental variations within the selected gammarid species are more extensive than previously thought. The ecological portion examines possible relationships between gammarid community development and physical and/or chemical factors and explores the migration habits of this group.