Unspecific histological and hematological alterations in anadromous and resident Salvelinus malma induced by volcanogenic pollution

The streams draining Kamchatkan volcanic areas are perfect natural models producing the long-lasting effects similar to inorganic anthropogenic pollution. The most abundant local fish species Salvelinus malma is able to reproduce under highly unfavorable conditions: contamination with heavy metals and mineral suspensions. The aim of this study was to assess the adaptability of the landlocked and anadromous populations in adverse conditions. Here, we examined the liver toxicant accumulation in the overwintered S. malma juveniles, as well as aberrations in gills, internal organs, and peripheral blood. Compared to the anadromous populations the landlocked populations demonstrate poor ability to develop the mechanisms of decreasing toxicants’ bioaccumulation. The sets of histological and hematological alterations demonstrated a striking similarity for both ecotypes, and the difference in occurrence of tissue alterations was mostly insignificant. Extreme negative effects of the heavily polluted environment were: the secondary lamellas’ fusion, necrosis of liver and spleen tissues, erythrocyte morphological abnormalities, and elimination of germ cells. We suppose that the resistance to organs’ malfunctions is not the main adaptive vector in S. malma populations in the polluted streams, and expect the same long-term pattern of injury in the resident fish populations under anthropogenic pollution.