Baltic Sea Aquatic Ecosystems in a Gradient from Land to Open Sea

Abstract

Situated in a gradient from land to the open sea, coastal water bodies can be separated into outer coastal waters and inner coastal waters. The southern Baltic Sea shows mostly lagoon-like coastal waters. Though connected to the open sea, such coastal lagoons are protected by land splits or similar land features and therefore highly exposed to influences from terrestrial ecosystems, especially nutrient runoff causing eutrophication. In the confusing complexity of different, often regional names for these ecosystems, we here use a terminology originating from the international literature. ‘Estuarine lagoons’ are inner coastal water bodies with high contribution of terrestrial inflows and “marine lagoons” are inner coastal water bodies without a major freshwater input, but high water exchange with the open Baltic Sea.