Diversity and ecological significance of deep-burrowing macrocrustaceans in coastal tropical waters of the Americas (Decapoda : Thalassinidea)

Deep-burrowing thalassinidean shrimp, commonly called mud shrimp or ghost s hrimp, dominate soft substrates and benthic processes in many coastal setti ngs. Among the more common genera in tropical intertidal to shallow subtida l areas are Lepidophthalmus and Callichirus, associated with muddy estuarie s and quartzite sand beaches, respectively, and the less well-known laomedi id genus Axianassa, associated with red mangroves. Recent studies of these and varied relatives suggest that sediment turnover by these deep-burrowers and facilitation of nutrient flux by burrow ventilation can be of major si gnificance to associated autotrophs, and may, dominate benthic processes in some communities. Habitat perturbations, contamination and hydrological al terations may render populations of these obligate burrowers vulnerable to mass mortalities, of special concern for those species that are regionally endemized. Under yet other circumstances, organic enrichment of habitat sub strates, particularly in aquacultural settings, may, induce explosive popul ation increases. Either of these dynamics could result in negative impacts on water quality and productivity; and contribute to the decline of associa ted plant and animal communities. Conservation of these burrowing shrimp co mmunities requires thorough understanding of their life histories, habitat dependencies, symbiotic relationships, and population responses to environm ental perturbations.