Growth, survivorship, and nutrient uptake of giant clams (Tridacna) in aquaculture effluent

摘要

Experiments were conducted to evaluate the feasibility of using juvenile giant clams (Tridacna) to remove dissolved inorganic nutrients (nitrate and phosphate) from aquaculture effluent. Three (T. derasa Roding, T. maxima Roding, and T. squamosa Lamarck) of the four species tested during a two-month experiment all had very high survivorship in both effluent and control seawater, but T. gigas (Linne) experienced 50 percent mortality. T. maxima and T. squamosa showed virtually no growth in both effluent and control waters. T. gigas had the fastest growth rate among the four species. T. derasa grew significantly faster in effluent than in seawater. In a 24-h experiment (12 h dark followed by 12 h light), all the four species absorbed similar and significant amounts of nitrate and phosphate from effluent during the light period. Our study demonstrates that although it may not be possible to rely on giant clams alone to remove all excess dissolved nutrients from intensive food fish aquaculture effluent, it is entirely feasible to use giant clams to remove all excess nutrients in effluent of marine ornamental species. Giant clams can be either incorporated into a polyculture system with other marine aquarium trade species, or they can be grown in effluent in separate tanks.