Cadmium Accumulation and Toxicity in The Bottlenose Dolphin Tursiops truncatus, The Common Dolphin Delphinus delphis, and Some Dolphin Prey Species in South Australia.

Abstract

Twenty Tursiops truncatus and 20 Delphinus delphis from South Australia were analysed for cadmium levels, as were some fish and squid species which form part of their diet. In the dolphins, cadmium was accumulated mainly in the kidneys (range 0-38 μg/g), with levels in many individuals exceeding 20 μg/g (wet weight). On average, levels in kidney were three-fold higher than in liver and 26-fold higher than in muscle. Cadmium concentrations related to dolphin body length, but the relationship with tooth development class was less clear. 80% of the prey fish species analysed from Spencer Gulf exceeded NH & MRC health recommendations of 0.2 μg/g (wet weight) for human consumption. Sepioteuthis australis from upper Spencer Gulf contained significantly higher cadmium levels than Ceduna samples (0.21 ± 0.01 μg/g versus 0.13 ± 0.01 μg/g, p<0.001) (wet weight). On histological examination, 32% of adult dolphin kidneys showed pathological changes, proteinuria being the most common abnormality. High levels of cadmium were found in dolphins from widely spaced locations in South Australia.