The composition, structure and functional characteristics of macrobenthos in the coastal zone of the Primorsky Krai (Sea of Japan)

The intense anthropogenic load and the high economic exploitation of marine biological resources in the coastal part of the Primorsky Krai (Sea of Japan) cause a comprehensive study of the marine environment and biota conditions. Macrobenthos is one of the essential components that determines the normal functioning of the marine ecosystem. We studied the composition, structure, and quantitative characteristics of macrobenthos and their functions. We grouped all coastal zones into four groups: (1) open areas subject to the influence of the prevailing river flow and minimal impact of the marine fleet; (2) open areas of the north-eastern and northern coasts, where the accumulation of organic matter (OM) is not observed; (3) water areas with naturally elevated OM content and local anthropogenic impact; and (4) the most polluted territories, subject to the intense chronic influence of factors of accumulation of OM, mainly of anthropogenic origin. The Golden Horn Bight is the water area subjected to the most significant anthropogenic impact, while the Kievka, Udobnaya, and Rudnaya Bights, on the eastern coast of Primorsky Krai, are the areas with the smallest level of anthropogenic press. The water areas of Nakhodka, Vladimira, Vostok, and Troitca Bight, enriched in organic matter, occupied the intermediate position. We revealed that the most significant components of macrobenthos-macrophytes and bivalves-cease to work as an effective biological filter, and the transformation of incoming pollution in the water area is too slow in conditions of chronic pollution of coastal marine ecosystems. The heterotrophic community feeds on a significant amount of introduced organic matter, often of toxic origin, the nature of which probably affects the functioning of mass groups of organisms, reducing the indicators of biodiversity and abundance.