Exploring the sea in winter

#OURSEA, the joint campaign of Moomin Characters and the John Nurminen Foundation, informs people of the Baltic Sea and of different ways to help the sea. At the same time, we raise funds for the John Nurminen Foundation's work to save the Baltic Sea and its heritage. This blog will take its readers on an expedition to the wintry world of the Baltic Sea.

“The sky was almost black, but the snow shone a bright blue in the moonlight. The sea lay asleep under the ice, and deep down among the roots of the earth all small beasts were sleeping and dreaming of spring. But spring was quite a bit away because the year had only just got a little past New Year.” Moominland Midwinter

The warmth of summer is still stored in the seawater, and often the Sea will have no ice until late in the autumn and winter. On chilly days, the humidity and warmth that rise from the sea will condense into sea smoke, slowly inching its way towards the coastline.

In winter, the Baltic Sea is covered by ice to a varying degree: sometimes, the Baltic Sea is frozen up far to the south from Åland, but these days it is increasingly common that the open sea is iceless all through the winter, with the northernmost nooks being an exception. Most often, though, the coastal waters of Finland freeze up even if the open sea is free from ice.  Each year, moving ice efficiently polishes away the blue mussels and perennial algae from the coastal cliffs of northern Baltic Sea, which is why only annual plants thrive on the rocks close to the water’s surface.

In winter, underneath the snow and ice, the Sea is dark and cold. Perennial bladderwracks have descended down to the seabed for their winter rest. The fish are resting, saving their energy and looking for the depths where temperatures stay close to four degrees and where they can overwinter. Others are active also in the winter: the burbot, for example, spawn in the wintertime under the ice, on the shallow, sandy and gritty delta riverbeds.

Learn more about Baltic Sea fauna

Blue mussel
The blue mussel is the most abundant species of the Baltic Sea, and an important source of nutrition for the flounder and the common eider. For their own nutrition, the mussels sieve tiny plankton from the sea. During one year, the blue mussels of the Baltic Sea sieve through a volume of water that corresponds to the entire sea! The blue mussels are the waste management system of the Baltic Sea.

© Miina Mäki

The mystical burbot is at home in the depths; it is an inland water fish, well adjusted to cooler waters, but also found in the coastal waters of the Baltic Sea where salinity is low. The burbot arrived in Finland right after the ice age, and is therefore one of our oldest fish species. It thrives in clear waters with plenty of oxygen, which means that eutrophication of the Baltic Sea is a severe problem for this species. From the barbel that sticks out under its chin, we can tell that the burbot belongs to the order Gadiformes.

Let’s save #OURSEA together

