Enhanced growth of the giant clam, Tridacna derasa (Roding, 1798), can be maintained by reducing the frequency of ammonium supplements uri icon


  • Juvenile giant clams, Tridacna derasa (Roding, 1798), of 14-17 mm shell length were exposed to no (control), two, three, or five additions of 40 mu M ammonium sulfate per week in mass culture conditions for 45 days. Growth of clams, in terms of increase in wet weight and shell length, was significantly greater in the ammonium-enriched conditions compared with the control; however, no significant differences in growth occurred among juveniles exposed to ammonium for 2, 3, or 5 days/wk. Mean density of zooxanthellae per clam also increased significantly with increasing frequency of ammonium addition. The degree of fouling by epiphytic algae (Boodlea sp. and Enteromorpha sp.) was significantly greater in tanks receiving ammonium 5 days/wk than in tanks receiving ammonium twice per week. These results indicate that supplementing with ammonium sulfate 2 days/wk is sufficient to maintain high growth rates during land-based culture of juvenile T. derasa. The reduced frequency of these nutrient supplements also helps alleviate algal fouling in rearing tanks

publication date

  • 2008