Cadmium Aqueous Exposure and Uptake of the Estuarine Isopod Cyathura carinata

Abstract

Cadmium (Cd) is a non-essential heavy metal, considered a high-priority pollutant. It occurs naturally in the environment but anthropogenic activities may enhance its presence, with consequences to the biota. Metal research has been focused in the crustaceans but knowledge on estuarine isopods has been lacking. The aim of this study was to assess the bioconcentration kinetics in the estuarine key species Cyathura carinata. This isopod was exposed to different treatments of Cd, through aqueous pathway: control, low (I), medium (II) and very high (III) concentrations during 14 days, being collected along seven sampling times. After the end of the exposure period, the mean uptake rates were 0.023, 0.040 and 0.634 μg g−1 day−1 for each treatment, respectively. Statistical differences in accumulated Cd were recorded between treatments, except between control and treatment I. A linear pattern of accumulation through time was detected for all the concentrations, being most perceptible in the treatment III, where measured Cd in C. carinata’s tissues was significantly different between all the sampling times. Cd accumulation in treatments I and II was not so pronounced, being only noticeable at the end of the exposure period. In these treatments, final concentrations were two and almost four times greater than control, respectively, while in treatment III Cd concentration increased 60 times. Survival did not seem to be affected in the various treatments, suggesting the existence of a strategy for preventing toxic activity of Cd that needs further investigation.