Response of submerged aquatic vegetation to eutrophication-related environment descriptors in coastal waters of the NE Baltic Sea

A national water quality classification system for surface waters based on type-specific reference conditions that fulfils the EU WFD requirements was established in Estonia in early 2007. The main objective of the current study was to test the Submerged Aquatic Vegetation (SAV) indicators included in the Estonian national assessment scheme against most commonly used parameters applied to describe the eutrophication situation. The aim was to detect possible regional differences in indicator response and to contribute to further development of those indicators. Depth distribution of phytobenthos, depth distribution of Fucus vesiculosus, and proportion of perennial plant species are currently used as SAV-related water quality indicators in the Estonian national system. All three indicators showed the strongest correlation with water transparency. The Southeastern Gulf of Finland was the water type showing in most cases the strongest relationship between eutrophication variables and the three tested SAV indicators. The performance between the tested variables was poorest in Parnu Bay and the Vainameri area. Revision of the used indicator system is needed in these areas.