The eastern Gulf of Finland—brackish water estuary under natural conditions and anthropogenic stress

Abstract The eastern Gulf of Finland (EGoF), in the Baltic Sea, was investigated in 2012–14 in order to reveal the structure and forces driving the formation of benthic landscapes. Broadscale environmental and biological (macrozoobenthos) data were collected with remote sensing and geological and biological field work methods and processed with multivariate statistics. The resultant series of GIS maps, included benthic marine landscapes maps, based on associated environmental variables and benthic assemblages. Hydrooptic and hydrological conditions in conjunction with salinity and topography, determine the current spatial distribution of nine major benthic landscapes in EGoF. Analyses of geological data (e.g., multibeam, backscatter and side-scan sonar data) and precisely collected macrozoobenthos samples at three key areas, situated in different part of the Russian sector of EGoF allowed the compilation of detailed marine benthic landscape maps. The results illustrate the importance of hydrooptic conditions, but also depth and substrate type for microscale distribution of macrozoobenthos. The macrozoobenthos is highly dominated by eurybiotic invasive species spatially distributed along the area according to their environmental requirements and sensitivity to sporadic natural and human impacts.