Effects on Growth of Juvenile Abalones Haliotis tuberculata Under Chronic Exposition to Metals Released from the Dissolution of an Aluminium-Based Galvanic Anode

Abstract

In the marine environment, the galvanic anode cathodic protection system (GACP) undergoes oxidation and releases metals in the forms of ions or oxy-hydroxides into the environment. The objective of the present study was to investigate the toxicity of a cocktail of metals released from the dissolution of an aluminium-based galvanic anode (~ 95% Al, ~ 5% Zn) on the abalone Haliotis tuberculata. Juveniles were exposed for 16weeks (i.e. 12weeks of exposure and 4weeks of decontamination phase) and their growth, intake rate, conversion rate and metallic concentrations were monitored. A total of 6 conditions were tested: a control, 4 concentrations based on Al and a trophic control. Results showed that the mortality reached 57% for individuals exposed to 1125µg L-1 of Al, and the abalone growth significantly decreased for an Al concentration greater than 495µg L-1. At the highest exposure concentration, intake rate measurements revealed that the appetite of abalones was affected, supported by the large increase in the conversion rate which was indicative of a poor feed efficiency. The monitoring of metallic concentrations showed that H. tuberculata strongly bioconcentrated Al relative to zinc. The diet did not appear to be the primary pathway for metal entry. Concentrations that significantly impacted abalone growth and survival during the experiment were higher than those found in natural environment, but the bioconcentration of Al into the tissues of a primary consumer such as abalone may be a potential pathway for Al to enter food webs.