On critical levels of ecological status for macrozoobenthic communities in Peter the Great Bay of the Japan Sea: field studies

Relationship between the environmental stress index (PES) and the mean total explained variance of biotic parameters (MEV, as a measure of the environmental factors influence on macrozoobenthic communities) is determined using the methods of multiple linear stepwise regression analysis and non-linear estimation. The relationship is S-shaped, with the points of beginning and end of linear growth confined to the PES ≈ 15–16 % and 30 %. These levels should be considered as boundary criteria for the status of macrozoobenthic communities. Under favorable environmental conditions, PES does not exceed 15 % (the first critical level), that is close to a «biologically balanced» state of the communities. The PES values in the range of 15–30 % indicate an increased influence of limiting factors, but this influence is not destructive. The PES values > 30 % (the second critical level) indicate extreme deterioration of habitat conditions and transition to a «physically controlled» state of the communities.