July 11, 2005 Do you enjoy eating oysters on a hot sunny afternoon? Make the most of it – it may not last forever. Research has shown that global warming increases the sensitivity of oysters to metal pollution, causing a deadly threat to populations in polluted areas. Dr. Gisela Lannig from the University of North Carolina, USA, will present her work on cadmium poisoning in eastern oysters (Crassostrea virginica) on Monday 11th July at the Society for Experimental Biology Annual Main Meeting in Barcelona [session C2].
Oysters are cold-blooded organisms so their body temperature changes with environmental temperature. Lannig observed that cadmium levels increased the basic metabolic rate (BMR) of oysters at 20ºC and 24º. For oysters at 28ºC, cadmium did not increase the BMR, but it significantly reduces its chances of survival. "One possible mechanism for this observation is increased damage of mitochondria in cadmium-exposed oysters with increasing temperature", Lannig explains, "these organelles become significantly more sensitive to cadmium as temperature rises, so that cadmium levels which were not damaging to mitochondria at lower temperature become strongly toxic with increasing temperature."
Cadmium circulates continually between air, water and soils. As it moves easily through the food chain, high levels are reported in seals. In humans, cadmium interferes with calcium metabolism and deposition in the bone. Accumulation over time can cause serious illnesses such as itai itai disease. Future research will focus on to what extent cadmium reduces thermal tolerance of cold-blooded species.
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