The nature of the Baltic Sea, with its low temperatures and brackish waters, is unique. As a consequence of human activity, however, marine biodiversity is under threat. Loss of local habitats, the unsustainable use of marine resources, and other environmental stress factors, such as environmental toxins and pharmaceuticals ending up in the sea, all weaken the vitality of marine nature. The Baltic Sea’s biodiversity is also threatened by the impact of climate change and eutrophication, in particular: they impact marine life in all environments.
Underwater habitats and key species
Biodiversity does not mean only an abundance of different species. The underwater nature of the Baltic Sea is not uniform and the same everywhere: underneath the surface there is a plethora of environments, each with a particular set of species. Environmental conditions, such as the material of the seabed and the strength of waves or of light, define what species will thrive at each location. The species of a community are in constant interaction, which is why changes in the survival of any one species will impact the others as well.
Bladderwrack, common eelgrass, and the blue mussel are key species of the Baltic Sea, and play an important role in the Sea’s ecosystem in the way they maintain communities of species. The habitats created by bladderwrack and the common eelgrass are important to the fish and the small invertebrates of the Baltic Sea. They are also excellent spawning areas and safe spaces for fish fry. Perennial plants retain nutrients from the water for their growth, and a rich meadow of eelgrass may retain more carbon than a forest of the same size.
Blue mussels filter their nutrition from the water, at the same time cleaning the water. Amongst them live many kinds of small crawlies, and mussels and other bottom dwellers are an important source of food for e.g. the eider and for many fish, such as the flounder.
Food chains in the Sea
Food chains in the sea, as they are on land, are dependent on the energy of the sun, captured by plants. Among the primary producers found in the sea are tiny planktonic algae, and annual and perennial phytobenthos. The minuscule plankton organisms that eat microalgae are the food of larger animals, which again are hunted by larger predators. At the top of the food chain are the large marine mammals, predator birds, and humans.
The operation of the entire sea is based on food chains, and the way organisms interact with each other and with their environment. Each underwater environment has a distinctive network of food chains. If these food chains are disturbed, the marine ecosystem begins to function differently, which we will see as changes in the status of the sea.
A warming climate and warmer seawater change the food chains of the Baltic Sea, and in many ways impact underwater life in its entirety. As the water warms, southern non-indigenous species have an easier time of making the Baltic Sea their home, and some of these newcomers may pose a threat to the indigenous species of our Sea. Climate change also further accelerates the eutrophication of the Sea, and increases anoxia in seabeds.
Eutrophication weakens the state of marine nature
Eutrophication threatens the survival of the Baltic Sea’s diverse marine nature. Key species of the Baltic Sea, such as bladderwrack and eelgrass, suffer from murkier waters which decrease sunlight, vital to plants, in deeper waters. A surplus of nutrients also benefits the growth of annual thread algae. As a result of eutrophication, the volume of thread algae in the Baltic Sea has tripled. A thread algae mass will suffocate marine eelgrass meadows and underwater bladderwrack forests. The bottom-dwellers of the Baltic Sea, on the other hand, suffer from anoxic seabeds, maintained by eutrophication.
Eutrophication has been a boon also for the common reed, which grows by the shores of the Baltic. The open shorelines of earlier times are filled up as thickets of the common reed take over. At the same time, we lose open, mosaic-like coastal habitats that are important for birds and insects both underwater and in the low-growing meadows by the sea.
Protecting marine nature
The underwater nature of the Finnish coastline has been surveyed for a long period of time, and as a result of this work, many ecologically significant marine underwater areas (or EMMA areas) have been identified. The wellbeing of the Sea’s communities of species is linked to local habitats, which is why marine nature protection measures should also target the areas that are most important locally. Approximately 11% of the Baltic Sea’s underwater nature is currently protected in Finland, equalling only a third of the 30% goal set out in EU’s biodiversity strategy.
A diverse and healthy species community is more resistant to changes in the environment. Climate warming and eutrophication have already changed the Baltic Sea, and the inhabitants of the sea are challenged by the need to adjust to the fast-advancing changes.
The projects of the John Nurminen Foundation combat eutrophication and other environmental risks encountered by the Sea. The objective of the protection work is to reach a good ecological status for the Baltic Sea, i.e. no excess nutrients or algae, sufficient oxygen in the seabed, and a diverse and robust ecosystem. Our goal is a thriving Baltic Sea. Read more about our projects.