Early development of sand dollar <i>Scaphechinus mirabilis </i>in the water from different areas of Peter the Great Bay (Japan Sea)
Ecological state in the most polluted areas of Peter the Great Bay is described by some chemical parameters (salinity, dissolved oxygen content, phosphorus and nitrogen concentration), pollution (concentration of anionic surfactants, phenols, total petroleum hydrocarbons, and indices of organic pollution as COD (KMnO <sub>4</sub>) and BOD <sub>5</sub>), and results of bioassay. The chemical parameters were measured by standard methods. The parameters of pollution were generalized with the integral Water Pollution Index (WPI - exceeding of the pollution over the permissible level), separately for the southwestern Peter the Great Bay, Amur Bay, and Nakhodka Bay: all these water bodies were qualified as moderately polluted or polluted ones. Embryo-larval bioassay with sand dollar S. mirabilis was applied and showed abnormalities in early development of the species under exposure in the water from all tested sites. Negative correlation between the number of normally developing embryos and larvae and WPI was revealed. The highest pollution is determined in the Nakhodka Bay.