Underwater biodiversity

The ecosystem in the Baltic Sea is rather simple compared to some tropical aquatic environments. However, especially the coastal areas offer a variety of different habitats for a diverse array of species, resulting in rich biodiversity. The Baltic Sea is home to many different types of plants, algae and animals.

Species in the Baltic Sea are unevenly distributed. Habitats with the richest biodiversity are shallow waters near islands. Biodiversity is important, as biodiversity-rich ecosystems are more resilient and able to adapt to changing environmental conditions.

Keystone species, such as bladder wrack and blue mussel communities, uphold biodiversity by offering hiding places, habitats and nourishment for many other species. Many species also perform other important tasks that support the wellbeing of the sea. Blue mussels filter excess nutrients from the water, and eelgrass meadows mitigate climate change by storing carbon.

Species in the Baltic Sea are masters of adaptation. Most marine species will not fare well in the Baltic because of the water’s low salinity, whereas many fresh water species find the water too salty. To live in the Baltic Sea requires that the species are able to live on the edge of their comfort zones. This makes the sea’s ecosystem very unique but also very vulnerable. Small changes in salinity, for example, can cause dramatic shifts in the ecosystem.

Eutrophication and climate change threaten biodiversity in the Baltic Sea. In addition, the sea’s habitants also suffer from other pressures caused by intense human activity in and around the Baltic Sea. Mitigating eutrophication and climate change is essential to conserve biodiversity, but species must also be protected from these other human-induced pressures.