A comparison of physiological changes in carp, Cyprinus carpio, induced by several pollutants at sublethal concentrations. I. The dependency on exposure time.

Carp were exposed to 10 different pollutants at sublethal concentrations for 6, 24, or 72 hr. Blood, liver, and white muscle samples were taken after the exposure time together with samples of control handled fish. Serum concentrations of glucose, cortisol protein, and cholesterol were determined. Similarly, the liver and muscle glycogen contents were measured. The effects of the following pollutants were examined: aldrin (100 micrograms/liter), atrazine (100 micrograms/liter), DDT (50 micrograms/liter), dieldrin (20 micrograms/liter), endrin (2 micrograms/liter), hexachlorbenzene (100 micrograms/liter), lindane (100 micrograms/liter), methanol (1 ml/liter), 4-N-phenol (100 micrograms/liter), toluene (100 microliters/liter). The rises in serum glucose and cortisol were the most frequent changes occurring after exposure to the pollutants. A decline in plasma protein and cholesterol content was also often observed. Liver glycogen concentration increased first in most cases and was reduced after longer exposure. Muscle glycogen was affected differently, sometimes reduced by exposure to the pollutants. The experimental design allows for the gradual increase in toxicity of the pollutants used regarding the applied concentrations. Furthermore, the aim of the paper is to evaluate the tests for proof of toxicity of those chemicals. The determination of serum glucose and cortisol levels can be proposed as mostly useful. The clearest changes in all parameters were found after treatment with 100 micrograms/liter atrazine and 50 micrograms/liter DDT. When serum glucose and cortisol concentrations were quickly elevated, signs for exhaustion could be seen after 72 hr of exposure.