Flow-mediated resource competition in the suspension feeding gorgonian Plexaura homomalla (Esper)

To assess the importance of resource competition in suspension feeders, growth of a common Caribbean gorgonian Plexaura homomalla (Esper) was examined with and without conspecifics. Five small branch sections (i.e., transplants) from a single parent colony were set next to each other in a linear array on a cement flat and maintained in situ in an area characterized by oscillating flow. After one year, we found a systematic decrease in growth rate from the outer to the middle position on these flats, a pattern consistent with expectations of flow-mediated competition for water-borne resources. Competition for water-borne resources is seldom considered among reef taxa, but such competition can play an important role in affecting both intra- and interspecific interactions.