Enhancement Effect of Sea Urchin Grow-out Cages in Lucero, Bolinao, Pangasinan

A preliminary study was conducted on the environmental impact of sea urchin (Tripneustes gratilla Linnaeas) grow-out culture in Lucero, Bolinao, Pangasinan. It was hypothesized that the feces generated by the caged urchins (~6,000 individuals at any one time) might cause localised sediment organic enrichment and subsequent shifts in benthic faunal communities. Results from preliminary surveys conducted in April and August of 1999 indicated minimal impact of sea urchin grow-out culture on the local reef flat community. Some enhancement of faunal abundance and sediment organic matter content in the cage area were noted; however, the impact was limited to a radius of 5-25 meters from the grow-out cages. The enhancement effects appeared to be seasonal occurrences that were dependent on local currents and degree of wave exposure. Epiphyte biomass, total suspended solids, sediment grain size, and relative water movement seemed largely unaffected by sea urchin grow-out culture. However, more frequent and thorough samplings are needed to validate these initial results. The presence of localised enrichment in sediment organic content and epibenthic faunal density suggest the possibility of converting the sea urchin grow-out area into polyculture systems that would make more efficient use of the food resources available while minimizing potential anthropogenic impacts on the environment