Early spring testing of environments quality in the Novik Bay (Russky Island, Peter the Great Bay, Japan Sea) in April, 2023

Oceanographic and ecological properties were measured in the Novik Bay of Russky Island (Japan Sea) in early spring (April) of 2023, the indicating groups of microorganisms were examined. Good ecological state of the bay waters was detected. Stable density stratification was already formed, with the water temperature range from 2.3oС at the bottom to 10.0oС on the sea surface and salinity from 33.6 to 31.1, respectively. Dissolved oxygen content was high in the bottom layer (9.6–10.8 mg/L). In the surface layer, the oxygen content was lower, as well as chlorophyll a concentration. Abundance of the colony-forming heterotrophic microorganisms was rather low, so the waters of the bay were characterized as oligosaprobic and pure that indicated accumulation of easily accessible organic matter (accumulation predominated over destruction), apparently due to development of production processes. Some exceptions with zero balance between the production and destruction were found in the Trud Inlet, in the inlet of Sports Club, and at Podnozhye village. Bacteria of the sanitary-indicative group were recorded in small quantities at two stations where they indicated biological and fecal pollution of the water. Microorganisms growing on media with crude oil were observed everywhere, although their number was not high, so the waters of the Novik Bay were identified as low-polluted, in general. However, high abundance of phenol-resistant microorganisms at most of the stations was a signal of significant pollution by phenols, that could have both natural and anthropogenic sources. Metal-resistant microorganisms were not abundant in the surface layer that showed the minimal level of technogenic pressure. Their dominant group was Ni-resistant heterotrophs associated with combustion of hydrocarbon fuel.