| This work was part of environmental impact study conducted from August 2002 until October 2003 related to two 3000m3-Ocean Spar submerged open-ocean growout cages stocked with Rachycentron canadum and Lutjanus analis south of the island of Culebra, Puerto Rico. The principal objectives were to determine the local environmental effects of open-ocean submerged cage culture on water and sediment quality, as well as changes over time of some environmental quality parameters, including the feasibility of these operations on tropical marine waters. Nutrient concentration (ammonia-N, nitrite-N, nitrate-N, and phosphate) were evaluated bimonthly in the column water and interstitial water at fifteen stations around the cage and three depths for the water samples; likewise, several water and sediment quality parameters were analyzed (dissolved oxygen, water temperature, turbidity, chlorophyll-a, salinity and organic matter). Water analyses indicated that, in general, both cages and the control site showed similar nutrients concentrations throughout the months analyzed. Ammonia was the nutrient with the highest concentration; however, these values were relatively low and normal for these waters. Results of the first year indicate that this operation did not impact the quality of the water column, or the sediments even though large quantities of feed were introduced into the system. This was probably due to the large amounts of water flowing through the cages. The information obtained from this study provides a basis to evaluate the feasibility of this operation, encourages the open-ocean aquaculture industry. |
