Distribution of sublittoral vegetation at the continental coast of the Okhotsk Sea (within the limits of Khabarovsk Region)

Abstract

Spatial distribution of algae vegetation is considered for the area from the Uda Bay to the Ushki Bay (1100 km along the northwestern coast of the Okhotsk Sea) on the data of 10 surveys conducted by Pacific Fish. Res. Center (TINRO) at the depth from 2 to 12-35 m in 2002-2013 (3043 stations, including about 300 diving stations made by the author personally). Dominant species of sublittoral vegetation are few: 4 species of brown algae ( Saccharina gurjanovae, Alaria marginata, Pseudolessonia laminarioides , and Stephanocystis crassipes ) and a group of red algae ( Neoptilota asplenioides, Odonthalia corymbifera, Tichocarpus crinitus, Chondrus platynus, Neohypophyllum middendorffii , and Hymenena ruthenica ), other species can form the vegetation cover in local areas only. The algae belt reaches the depth 8-13 m, sometimes 26-35 m. Its vegetation is qualitatively homogeneous, with feebly marked vertical zoning and tier structure; the dominant species don’t change by latitude and topical conditions. Mean biomass of the sublittoral algae is about 2 kg/m 2 , with the greatest contribution of Saccharina gurjanovae (annual mean 41 %) and the minimal one of Pseudolessonia laminarioides (13 %). The species composition is relatively stable in time, as well. The features of vegetation homogeneity are shown in over 900 km of the coastal zone. However, the sublittoral vegetation changes significantly southwestward and northeastward from the investigated area.