Macrobiofouling on open-ocean submerged aquaculture cages in Puerto Rico.

摘要

Biofouling in aquaculture cages is known as a significant problem in aquaculture cage farm operations. The purpose of this study was to assess biofouling composition and percentage of biofouling coverage over time on nets of two open-ocean submerged aquaculture cages. The cages were located 3 km south of Culebra Island, Puerto Rico. Sample nets, each measuring 1050 cm2, using the same material of the cage netting, were fastened in four different locations on each cage (snapper cage-Lutjanus analis and cobia cage-Rachycentron canadum): above or below the cage rim; and upstream (predominant current) or downstream locations. The rim was located 16 m below the surface, at the middle of the cage. Biofouling growth was monitored from August 2002 to June 2003 by removing one net sample bimonthly from each location of each cage. In the laboratory phase, each sample net was photographed and Map Maker software (Version 1.0) was used to calculate the percent coverage. Individual organisms were identified to major groups (algae, sponges, hydroids, polychaetes, mollusks, crustaceans, ascidians, and bryozoans). There was no difference in biofouling coverage between snapper cage and cobia cage throughout the study (53% y 51% respectively). The sample nets attained 49% of biofouling coverage after two months of cage deployment. The percentage of biofouling coverage throughout the months analyzed was increased (71%) after 10-months of installation of the sample nets. This suggests biofouling growth after the two first months followed a classical succession process. Algae, hydroids, ascidians, bryozoans, and mobile organisms (polychaetes and crustaceans) were present in all locations. The above location had a higher abundance of algae (64%) and algal-hydroid assemblage (31%) than the below location which had abundances of algal-hydroid assemblage (46%), and algae (12%). The higher algal growth at the above location was probably stimulated by light availability. There were no differences in percent coverage and composition between upstream and downstream locations (51% and 54% respectively). Biofouling community growth in aquaculture operations in tropical areas could involve serious implications related to fish farming, but ecological benefits of biofouling must also be considered when developing appropriate prevention and control methods.