Insects and other invertebrates

Many different invertebrates also live beneath the surface. Several of them may be the larvae of various terrestrial insects, such as dragonflies and chironomids. Bivalves, crustaceans and polychaete help oxygenate the seafloor when they dig around in the soft bottom, and they are important food sources for both fish and birds. These benthic species can also be good indicators of water quality and pollution, as they are sensitive to changes in the environment.

Image 1: Brown Hawker (Aeshna grandis)

Image 2: River nerite (Theodoxus fluviatilis)

Image 3: River nerite (Theodoxus fluviatilis) to the left and Blue mussel (Mytilus edulis) to the right

Baltic tellin, the amphipod Monoporeia affinis, and Saduria entomon all belong to the most common benthic animals in Kvarken. The blue mussel, which has its northernmost distribution limit in Kvarken, can also be found on the harder bottoms in areas. And since mussels are an important food source of the common eiders, it means that the eider does not nest farther north than in the Kvarken archipelago. Both Monoporeia affinis and Saduria entomon are relic species. Originally they were spread out in a larger area, but after the ice melted and the land masses increased, they became isolated in the Baltic Sea. Both are important food sources for perch, fourhorn sculpin and houting. In the area you can also find various benthic worms (e.g. polychaetes), crustaceans (Mysis relicta and bay barnacles, which have their northern distribution limit here), and gastropods.

Image 4: Bay barnacle (Amphibalanus improvisus)

Image 5: Saduria entomon

Sources

Hietikko-Hautala T. 2010. Jääkauden jälkinäytös – Merenkurkun saariston maailmanperintö. Waasa Graphics, Vasa

Ollqvist S. 2005. Skötsel- och användningsplan för Mickelsörarna-Rödgrynnorna. Västra Finlands miljöcentrals duplikat 121/2005. Forststyrelsen, Vasa

Rassi P., Hyväringen E., Juslén A., Mannerkoski l. 2010. Suomen lajien uhanalaisuus – Punainen kirja 2010. Miljöministeriet och Finlands miljöcentral, Helsingfors

Rinkineva L., Bader P. 1998. Kvarkens natur. Kvarkenrådets publikationer 10, Vasa