Известия ТИНРО (Sep 2017)
Distribution of macrozoobenthic taxa - potential indicators of vulnerable marine ecosystems in the western part of Bering Sea. 2. Chukotka and Koryak districts
Abstract
Species composition of the most common species belonging to the taxa of macrozoobenthos - potential indicators of vulnerable marine ecosystems is considered on the data of bottom-sampler and bottom trawl surveys in the Chukotka and Koryak districts of the Bering Sea. The Chukotka district is mostly shallow-water area (prevailing depths 20-60 m) where these taxa-indicators are: sponges ( Myxilla incrustans , Halichondria panicea , and Semisuberites cribrosa ), barnacles ( Chirona evermanni ), ascidians ( Halocynthia aurantium and Boltenia ovifera ), octocorals ( Gersemia rubiformis ), bryozoans ( Cystisella saccata and Flustra foliacea ), and brittle stars ( Gorgonocephalus eucnemis ). Settlements of immobile sestonophages (the first 5 taxa) occupy mainly the hard or mixed bottom grounds in the coastal zone and movable filtrator (the last taxon) is distributed deeper on loose grounds. The Koryak district is deeper (up to 870 m depth); beyond the abovementioned taxa the other common taxa-indicators here are marine whips ( Halipteris willemoesi ), sea lilies ( Heliometra glacialis ), and sea anemones ( Actinostola callosa ) and 3 more species are common for octocorals ( Anthomastus rylovi, Paragorgia arborea , and Paragorgia sp.). The list of taxa-indicators includes immovable or almost immovable sestonophages (octocorals, sponges, ascidians, bryozoans, barnacles, sea whips, and sea lilies), moving filtrators (brittle stars) and predators (sea anemones). All these taxa could be divided onto 3 groups according to the depth of their occurrence: i) continental shelf residents (barnacles, bryozoans, sea squirts Boltenia ovifera and Gersemia rubiformis ); ii) continental slope residents (octocorals, sea whips and sea lilies); iii) interzonal dwellers (sponges, brittle stars, sea squirt Halocynthia aurantium , and sea anemones). The epibenthos is the most abundant in the area between Cape Navarin and Cape Haidin that obviously is the sign of high bioproductivity of this area. The data of long-term observations confirm high stability of distribution patters and abundance of the epibenthic communities in the western Bering Sea.
Keywords
