Close to the border of Finland and Sweden, in the outer archipelago of Tornio and Kemi, lies Perämeren kansallispuisto (the Bothnian Bay National Park). With rocky shores and shallow waters, the national park comprises around 30 moraine islands and islets.
We’re delighted to speak with Essi Keskinen, a Marine Biologist at Finland’s Metsähallitus, to dive into the ecological wonders of Bothnian Bay and its seasonal transformation.
Hi Essi, could you share some insights into the unique island landscapes within Bothnian Bay?
With its diverse island landscapes, Bothnian Bay National Park showcases a rich variety of ecological wonders, from rugged rocky shores to serene sandy beaches.
The islands and islets, each at a different developmental stage, capture the delicate balance between nature and human influence, offering a unique blend of ancient fishing bases, historic villages, and remnants of past civilizations.
Challenging to reach yet captivating in its isolation, the national park is a living testament to the interconnectedness of cultural heritage and ecological preservation.
Human activity seems to have left an indelible mark on these islands, can you tell us more?
The islands serve as historical archives of human presence over centuries. The remains of old buildings, weathered but still standing, offer a brief glimpse into the daily lives of the coastal communities that once thrived here, dating back to the late 16th century.
Supporting stones used as seamarks, strategically placed in times gone by, served as navigational aids for sailors, reflecting a practical aspect of human engagement with the sea. They symbolize the enduring connection between the islanders and the marine environment.
Shaped by natural forces like land uplift and human practices such as livestock grazing, the islands continue to stand as witnesses to the sustainable practices that have defined their cultural history.
The park continues to showcase the sustainable practices that define its history.
Photo: Pekka Aho.
From your perspective, what sets this marine protected area apart?
Bothnian Bay National Park stands out due to its location on a land uplift coast, where the Earth’s crust elevates around 9mm each year. This ongoing geological process causes new reefs and shoals to emerge, and the gradual rise of the islands from the sea creates a unique pattern of plant growth, adding to the national park’s distinctive ecological character.
The national park benefits from substantial inflows of river water from the huge northern rivers. This influx creates optimal conditions for more than 20 species of water mosses to thrive – which is a rarity for the sea.
The island shores are adorned with expansive meadows, which gradually transition into rows of willows further inland. At the heart of some islets, deciduous forests flourish. The highest peaks of the oldest islands, such as Selkä-Sarvi and Vähä-Huituri, boast juniper-covered heaths or stunted coniferous forests.
Can you tell us more about the types of biodiversity in Bothnian Bay?
The flowering beach meadows and juniper groves offer sanctuary for around 60 different bird species to nest, including the Arctic Tern (Sterna paradisaea, the emblem bird of the national park), Velvet Scoter (Melanitta fusca), and Temminck’s Stint (Calidris temminckii).
The area hosts several rare plant species that are only found in coastal uplift regions in Finland. This includes the emblem plant of the national park, Siberian primrose (Primula nutans var. jokelae), which only survives in places where uplifts cause new land to rise from the sea.
Below the water's surface, lies a unique blend of marine and freshwater species. The Baltic Sea relict crustacean (Saduria entomon) coexists with the freshwater duck mussel (Anodonta anatine), and the Baltic water-plantain (Alisma wahlenbergii), exclusive to the Baltic Sea, shares its habitat with the non-native Canadian waterweed (Elodea canadensis).
The Arctic Tern is the emblem bird of Bothnia Bay National Park.
Photo: Ismo Lampi, Metsähallitus
An adult Temminck's Stint walking through flowers.
Photo: Elina Schipkova, Adobe Stock
Siberian primrose is the emblem plant of the park.
Photo: Sari Airas, Metsähallitus
The Arctic Tern was the park's most abundant bird species, but numbers have declined.
Photo: Johanna Kehus, Metsähallitus
How do the seasons affect the biodiversity?
The Bothnian Bay is the northernmost and most brackish part of the Baltic Sea. The sea area is shallow, with a seabed consisting mostly of sand, greatly affected by river discharge from Finnish and Swedish Lapland.
In winter, the area undergoes a stunning transformation as Arctic conditions cover the sea in a thick layer of ice. The frozen landscapes create an ethereal beauty, inviting visitors to witness nature's transformative power. The ice covering becomes an important nesting habitat for the ringed seal (Pusa hispida) and an importing breeding ground for the grey seal (Halichoerus grypus).
The ice is a vital nesting habitat and breeding ground for ringed and grey seals.
Photo: Pekka Aho.
In summer, due to turbidity caused by high humus concentrations, the water’s brown colour and murkiness limit sunlight penetration, with most plants and algae produced within the shallowest waters.
Due to the extreme brackish water, the number of marine species is relatively low. However, conditions are suitable for freshwater species that can tolerate low salinity and cold temperatures. Sea-spawning whitefish (Coregonus lavaretus) and vendace (Coregonus albula) spawn in shores and reefs.
The sea-spawning grayling (Thymallus thymallus), an adaptable species that migrates from saltwater to freshwater for spawning, uses the rocky shallow shores of the outer islands as crucial breeding grounds for its larvae. Despite its ability to thrive in diverse environments, it is currently critically endangered due to threats such as habitat degradation, pollution, and overfishing. The national park now plays a crucial role in protecting this species as one of only two recognized spawning sites in Bothnian Bay, the other being the Krunnit nature conservation area.
Sea-spawning grayling breeds on the outer islands' rocky shores.
Photo: Vera Kuttelvaserova, Adobe.
What is being done to protect the area’s biodiversity?
Protection, conservation, and management efforts are crucial for preserving the diverse landscapes of Bothnian Bay National Park. Numerous measures are in place to help safeguard the park’s unique biodiversity.
For instance, there are restrictions on boat landing and movement near nesting bird sites that are enforced from May to July each year. This ensures that these crucial habitats are protected during the critical nesting period.
Additionally, specific regulations are in place to protect seals on Möyly Island, where a minimum distance of half a nautical mile must be maintained to minimize disturbances. The emphasis on responsible outdoor behaviour is important, promoting practices such as leaving no trace and proper waste disposal. Nature-friendly activities, including controlled camping, angling, and berry picking, are permitted but only under specific guidelines to minimize the impact on the fragile ecosystems that characterize the park.
Collectively, these measures strike a delicate balance between human activities and the protection of Bothnian Bay’s pristine natural environment, urging visitors to be stewards of this untamed northern Baltic treasure.
Responsible outdoor behaviour is important. Be stewards of the environment.
Photo: Pekka Aho.
Red List species
Among the species listed in this article, the following are identified in HELCOM’s Red List as the face the threat of extinction due to human activities or natural environmental variability. These species are in urgent need of special attention and conservation efforts:
Velvet Scoter (Melanitta fusca)
Temminck’s Stint (Calidris temminckii)
Baltic water-plantain (Alisma wahlenbergii)
Sea-spawning whitefish (Coregonus lavaretus)
Vendace (Coregonus albula)
Sea-spawning grayling (Thymallus thymallus)
The national park comprises around 30 moraine islands and islets.
New reefs and shoals emerge as the park is located on a land uplift coast, where the Earth’s crust elevates around 9mm each year.
New reefs and shoals emerge as the park is located on a land uplift coast, where the Earth’s crust elevates around 9mm each year.
New reefs and shoals emerge as the park is located on a land uplift coast, where the Earth’s crust elevates around 9mm each year.
New reefs and shoals emerge as the park is located on a land uplift coast, where the Earth’s crust elevates around 9mm each year.
New reefs and shoals emerge as the park is located on a land uplift coast, where the Earth’s crust elevates around 9mm each year.
Around 60 different bird species find sanctuary in the park's beach meadows and juniper groves.
New reefs and shoals emerge as the park is located on a land uplift coast, where the Earth’s crust elevates around 9mm each year.
The substantial inflows of river water create optimal conditions for more than 20 species of water mosses to thrive.
The substantial inflows of river water create optimal conditions for more than 20 species of water mosses to thrive.
New reefs and shoals emerge as the park is located on a land uplift coast, where the Earth’s crust elevates around 9mm each year.
The substantial inflows of river water create optimal conditions for more than 20 species of water mosses to thrive.
