Abstract
Some man-made substances and their by-products are known for their ability to affect the endocrine systems of animals. Physiological indicators of health were determined for wild populations of the marbled sole, Pleuronectes yokohamae.Fish were obtained from three sites of the central coastal area of Miyagi prefecture: two sites in Sendai Bay, which is affected by anthropogenic pollutants, and the eastern coastal regions of Ogatsu, which receives only low levels of pollutants.
No abnormality was observed in gonad morphol ogy. Mean values for hepatic microsomal cytochrome P-450 (Cyt.P-450) content were about 0.2nmol/mg-protein. However, in a few fish from Sendai Bay the amount was more than 0.4 nmol/mg protein. These fish showed slightly lower values for brain acetylcholinesterase (AChE) and plasma total thyroxine (tT4) in both sexes, and plasma teststerone (T) in males. A significant negative relationship between Cyt.P-450 and T levels was detected in these fish. A negative relationship between Cyt.P-450 and AChE, and between Cyt.P-450 and tT4 was also found.
These findings suggest that (i) the health of marbled sole inhabiting Sendai Bay is going to be influenced by exposure to environmental pollutants, including endocrine disrupting chemicals, but the effects are not so severe at present, and (ii) these indicators are available as biomakers of environmental pollution by xenobiotics. Furthermore,(iii) it is advisable to investigate the relation among several indicators, including hepatic Cyt.P-450 content, T, tT4 and AChE, as a means of assessing environmental pollution of this kind.
