Spatial distribution of macrozoobethos according to environmental conditions in the Lahepere Bay region

Abstract

This paper is based on the analysis of zoobenthic communities from Lahepere Bay of Estonian coastal sea and its region up to Estonian economic zone. The samples were collected on 3.-4. July of 2013 from thirteen stations using Van Veen grab with the opening area of 0.1 m2. From three stations no zoobenthos was found due to oxygen deficit in the near bottom layer. Bottom macrofauna was identified to the species level, abundance and dry biomass was also determined. In deeper areas of the study (57-60 m) only two to four species were found in each sampling station, whereas key species included Macoma balthica, Halicryptus spinulosus and Marenzelleria neglecta. In depth range 43-57 m the species composition consisted of five to seven species, including key species Monoporeia affinis and Bylgides sarsi in addition to previous. Shallower stations (12-34 m) had up to 17 species in one community, key species included bivalves. The results showed that zoobenthic communities were more diverse in the shallow Lahepere Bay with coarse sediment type. The sediment type changed from gravel and sand to mud or clay from the southern part of the Lahepere Bay towards the open sea area. Also the aims of this study, to provide initial physical and zoobenthic data for estimating changes in benthic invertebrate communities after possible anthropogenic impact in the future and to assess ecological quality status of macrozoobenthic communities in the coastal area of the Lahepere Bay region using the ZKI-based Ecological Quality Ratio (EQR), are achieved.