Effects of Nutrient Source, Temperature, and Salinity on the Growth and Survival of Three Giant Clam Species (Tridacnidae)

Abstract

The habitats of giant clams are undergoing environmental changes, and giant clam populations are declining. The present study was conducted to facilitate clam conservation. We conducted three 18-week trials to investigate the effects of nutrient, temperature, and salinity on the growth performance and survival rates (SRs) of juvenile Tridacna noae, adult Tridacna crocea, and subadult Tridacna derasa, respectively. Regarding nutrient sources, no significant differences were observed in shell length gain, specific growth rate, or SR between clams fed with Chaetoceros muelleri or commercial feed (hw nanotip) and those in a control group (juvenile phototrophs). Regarding temperature, clams cultivated at 27 degrees C exhibited significantly better growth performance and SR than did those cultivated at 19 degrees C or 31 degrees C (p < 0.05). By week 6, all clams in the 19 degrees C and 31 degrees C groups had died, indicating that suboptimal growth temperatures have severe adverse effects. Regarding salinity, clams cultivated at 34 parts per thousand exhibited significantly higher length gains and specific growth rates than did those cultivated at 20 parts per thousand or 25 parts per thousand (p < 0.05). SR was not significantly affected by salinity. Understanding how environmental factors affect giant clam populations may help researchers devise effective clam conservation strategies.