STRUCTURAL AND FUNCTIONAL CHARACTERISTICS OF BIOTA IN MARINE ECOSYSTEMS AS A BASIS FOR ECOSYSTEM RISK ASSESSMENT

Abstract

The paper summarizes the theoretical and methodological foundations for using structural and functional characteristics of biota to assess ecosystem risks in marine ecosystems. It is shown that biotic indicators are particularly informative, as they integrate the ecosystem response to the combined effects of natural and anthropogenic factors through changes in community composition and organization, trophic interactions, matter and energy flows, as well as the balance of key functional processes. The feasibility of combining morphofunctional indicators, metabolic indicators of ecosystem functioning, indicators of natural resilience, anthropogenic pressure, and ecological state for the quantitative interpretation of ecosystem risk is substantiated. Using the Odesa Bay as a case study and applying the AQUATOX model, the relationship between impact factors and ecosystem state indicators was analyzed, along with the features of ecosystem risk dynamics in static and dynamic phase spaces. It is shown that under conditions of increasing anthropogenic pressure and acceleration of ecosystem processes, the system may shift from a regime of adaptive reorganization to a less stable state. These processes are accompanied by increased variability, disruption of the balance between production, consumption, and decomposition of organic matter, reduced self-regulation capacity, and a higher probability of transition to an alternative risk state. Such a transition is manifested in changes in the structural organization of biota and a weakening of compensatory mechanisms. The proposed approach makes it possible to combine hydrobiological diagnostics, stability assessment, and risk analysis using mathematical modelling methods. It can be applied to improve marine environmental monitoring, assess ecological status, and support management decisions aimed at reducing ecosystem risks.