Abstract:
The effects of cadmium and mercury on adaptive physiology of shrimps (Penaeus monodon) was conducted in Marine Science Laboratory, Faculty of Science, Burapha University. The aims were studied survival rate LC50, oxygen consumption, osmoregulation and accumulation of these heavy metals in shrimps.It was found that percentage survival of shrimps in seawater with cadmium concentration of 0.0, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 and 4.0 ppm within 96 hours were 100%, 100%, 100%, 90%, 67%, 17%, 13% and 0% respectively, and 96h LC50 was 2.42 ppm. Survival percentage of shrimps in seawater with mercury concentration of 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5 ppm within 96 hours were 100%, 100%, 80%, 40%, 17% and 0% respectively, and 96h LC50 was 0.25 ppm. Oxygen consumption rate of shrimps reared in sewwater with cadmium concentration of 0, 0.1, 0.5 and 1.0 ppm were 6.21+-1.53, 6.92+-1.21, 4.87+-1.24 and 4.37+-12.8 umol/g/h respectively. Oxygen concumption rate of shrimps reared in seawater with mercury concentration of 0, 0.01, 0.05 and 0.1 mg/l were 6.14+-1.33, 5.65+-1.03, 5.07+-0.80 and 4.17+-1.13 umol/g/h respectively. For osmoregulation study osmolality in shrimp reared in seawater with cadmium and mercury found decreased with the increasing concentration of both heavy metals. Osmolality in shrimp reared in seawater with cadmium concentration 0, 0.1, 0.5 and 1.0 ppm were 636.50+-10.33, 628.21+-8.66, 591.29+-7.37 and 559.93+-7.94 mOsmol respectively. Blood osmolality of shrimp reared in seawater with mercury concentration 0, 0.01, 0.05 and 0.1 ppm were 686.71+-7.23, 626.0+-13.48, 573.25+-14.38 and 536.71+-7.25 mOsmol respectively. Cadmium and mercury accumulation analysis of in the reared shrimps showed that the concentration of cadmium and mercury in the head region of shrimp was higher than in the body the concentration in both parts increased with the increasing of the concentration of cadmium and mercury.The results, it is indicated that shrimps may not abruptly died after exposed to cadmium and mercury, both heavy metals may accumulate in shrimps had effect on their physiology. Changes in the oxygen consumption rates and osmolalities of shrimps may be and ecological indicator of the shrimps may be and ecological indicator of the shrimps' habitat.