Effects of Cu, Zn and Cd on larval development and respiratory metabolism of pacific abalone (Haliotis discus hannai)

Trochophore and veliger are vulnerable pelagic larvae and susceptible to environmental toxicants, which are extremely crucial for the population renewal. Cu, Zn and Cd pollution are common elements in metal pollution in coastal areas. Though Pacific abalone is the main economic mollusc in China, its larval response to metals remains unclear. To understand this, the effect of Cu, Zn and Cd toxicity on malformation classification and respiratory metabolism of trochophore and veliger are analysed and measured in this paper. The 48 hr EC(50)for abalone trochophore was (18.9 +/- 1.0) mu g/L for Cu, (65.1 +/- 0.3) mu g/L for Zn and (1,377.8 +/- 68.9) mu g/L for Cd respectively. The LC(50)of veliger was (45.8 +/- 0.9) mu g/L for Cu, (50.0 +/- 0.9) mu g/L for Zn and (1,049.3 +/- 37.6) mu g/L for Cd respectively. Trochophore died with no shell at 128 mu g/L Cu, yet remained alive with multiple broken-shell bodies at 128 mu g/L Zn and failed to form well-developed shells at 20,480 mu g/L Cd. All veliger died with complete shells at the mentioned concentrations. A self-made device was used to study the effect on respiratory metabolism. The respiratory metabolism level was significantly fluctuating under Cu and Zn exposure and declined under Cd. The results indicated a decreasing order of the metal toxicity to trochophore and veliger as follows: Cu > Zn >> Cd. Cu and Zn were the main causes of shell abnormality, and Cd was less toxic. Moreover, the affected respiratory has a negative impact on further larval development.