In a paper presented 11 July at the Society for Experimental Biology's annual meeting in Barcelona, scientist Gisela Lannig said her research showsthat global warming increases the sensitivity of oysters to metal pollution, causing a deadly threat to populations in polluted areas.
The demand for prepared meals has led to the increased use of oysters in a wide range of frozen convenience foods, according to an Food and Agriculture Organisation report on aquaculture in the UK.These include the traditional smoked and brined oysters, and also new products developed by the UK's Sea Fish Industry Authority.
Oysters are cold-blooded organisms so their body temperature changes with environmental temperature. Lannig observed that cadmium levels increased the basic metabolic rate of oysters when thetemperature rose to between 20ºC and 24ºC. For oysters at 28ºC, cadmium did not increase the metabolic rate but significantly reduced the oyster's chances of survival.
"One possible mechanism for this observation is increased damage of mitochondria in cadmium-exposed oysters with increasing temperature," Lannig said. "These organelles becomesignificantly 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 is a widespread toxic metal in the environment that accumulates in the human body. It can cause damage to all types of body cells and at high levels can cause enteritis, an inflammation ofthe intestine.
Cadmium also interferes with calcium metabolism and deposition in the bone. Accumulation over time can cause serious illnesses such as itai itai disease. Lanning did her research on cadmium poisoning in oysters found in the eastern part of the US.
In a bid to market the UK's oysters, the Sea Fish Industry Authority has developed a range of possible products using oysters including breaded meals, meats in flavoured batter, boil-in-the-bagdishes such as oyster mornay and sweet-and-sour oysters, oysters in the half shell, au naturel or with added sauce and oyster flans. Several of the products have been test marketed.
Global warming refers to the process by which the Earth's atmosphere is on average slowing warming up because of the release of "greenhouse gases" such as carbon dioxide. TheIntergovernmental Panel on Climate Change (IPCC) recently concluded that increased concentrations of greenhouse gases are causing an increase in the Earth's surface temperature. In some regionsincreased concentrations of sulfate aerosols have led to relative cooling.