Assessment of the State of Flounders from Sivuch'ya Bight (Peter the Great Bay, Sea of Japan) Based on Histopathological Parameters

Abstract

The liver and gills of five flounder species (Pleuronectes obscurus, P. punctatissimus, P. yokahamae, P. herzensteini, and Platichthys stellatus) from Sivuch'ya Bight were histologically studied. Specimens of all species were characterized by a wide spectrum of histomorphological changes. The proportions of most specific pathologies in P. obscurusfrom Sivuch'ya Bight were estimated. The pathologies comprised two major groups: those of the gills (edema and fusion of the respiratory lamellae; lifting and hyperplasia of the respiratory epithelium; vacuolization of the epithelium cells; and the presence of clavate lamellae, aneurysmal areas, and parasites) and those of the liver (vacuolization of the hepatocytes, aneurysms, necrosis of the parenchyma tissue, pathologies of the hepatocyte nuclei, pigment accumulation, and an increase in the number and size of melanomacrophage centers). The estimated proportions of pathological changes were compared with those observed in P. obscurusspecimens from the most contaminated area of Amurskii Bay. In both Sivuch'ya Bight and Amurskii Bay, the proportion of fish with various pathologies was high. The comparison of pathological changes in the gills and liver of P. obscurusand P. stellatusfrom Sivuch'ya Bight showed that, in terms of many parameters, the former species is more sensitive to pollution of the marine environment than the latter. Pathomorphological changes in the organs of the flounders studied are apparently caused by chronic pollutant action and suggest that the fish of both areas are in a damaged state.