TP11 Metals in the Environment: Aquatic Biological Perspectives
Tuesday, 15 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(KHA-1117-728130) Global Warming and Aquatic Animals In Toxic Environments.

Ahmad, S., Ajay, O., Razo, P., Vaughan, M., Khan, M.,

ABSTRACT- Aquatic animal species differ in their sensitivity to heavy metals. For example, zebra mussels (Dreissena polymorpha) and water flea (Daphnia magna) are more sensitive to copper than cadmium, lead, and zinc while baby crayfish (Orchonectis immunis) are more sensitive to cadmium than other metals. The toxicity of these metals increases with rise in acclimation temperature. A 4-5 degree C increase can make copper 400% and 100% more toxic to respectively mussels and daphnids (Daphnia magna) . This rise in temperature can increase the rate of aerobic metabolism (oxygen consumption) by about 100% in mussels and 30% in crayfish and daphnids. These heavy metals inhibit the rate of respiration and seem to inhibit the temperature-related increase in respiration in all these animals although to different extents. Copper can increase the rate of oxygen consumption up to 50% during a 20 to 27 degree C rise in temperature in crayfish, which can be inhibited further (in mussels) if the concentration of copper is increased. Accordingly, the temperature increases due to climate change (global warming) can pose threat to survival of aquatic ectothermic animals whose metabolism is dependent on ambient temperature. Increase in water temperature, in addition to increasing the metabolism (increase in oxygen consumption), can lower the concentration of dissolved oxygen in water. Temperature can also increase the concentration of heavy metals in water due to their desorption. All these factors together can make sublethal/subtoxic environments become lethal to aquatic animals. Such effects, if related with climate change, need extensive investigations.

Key words: Metals, Toxicity, Aquatic, Temperature