Küstenseen

Küstenseen, or coastal lakes, are inland water bodies located in coastal landscapes such as barrier beaches, dunes, and deltas. They are typically semi-enclosed and retain a connection to the adjacent sea, which gives them brackish or saline conditions distinct from inland freshwater lakes. Their size, depth, and degree of exchange with seawater vary across regions and over time.

Formation and dynamics: Many Küstenseen are formed by coastal geomorphology after sea-level rise or land uplift, creating depressions behind barriers that trap seawater. Tidal exchange occurs through inlets or channels, while groundwater inflow and river inputs provide fresh water. Changes in barrier integrity, storm events, or human infrastructure can alter water exchange and salinity, shifting a lake along the freshwater–brackish–salt continuum.

Ecology and environment: The brackish environments of Küstenseen support specialized plant and animal communities, including eelgrass beds, certain fish and crustaceans, and a diverse waterfowl population. Nutrient loading and limited flushing can drive eutrophication and algal blooms, whereas strong exchange with the sea can enhance resilience. Many of these lakes are part of protected coastal ecosystems and are subject to conservation and restoration efforts.

Distribution and examples: The concept applies to coastlines worldwide, with notable occurrences along temperate coasts in Europe and North America. In German-speaking regions, Küstenseen are described along the Baltic and North Sea coasts, where they are studied for their geomorphology, hydrology, and biodiversity.

Conservation and research: Küstenseen inform coastal zone management, climate-change impact studies, and investigations into freshwater–saltwater interactions. They serve as indicators of shoreline dynamics, wetland health, and coastal resilience, while supporting local biodiversity and, in some areas, ecosystem-based tourism.