''Monoporeia affinis'', formerly referred to as ''Pontoporeia affinis'' ( el, Πόντος, ' =

Pontus Pontus or Pontos may refer to: * Short Latin name for the Pontus Euxinus, the Greek name for the Black Sea (aka the Euxine sea) * Pontus (mythology), a sea god in Greek mythology * Pontus (region), on the southern coast of the Black Sea, in modern ...

/ Black Sea; , ' = to travel), is a small, yellowish

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

amphipod Amphipoda is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods range in size from and are mostly detritivores or scavengers. There are more than 9,900 amphipod species so far descr ...

living in the

Baltic Sea The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the North and Central European Plain. The sea stretches from 53°N to 66°N latitude and from ...

, the

Arctic Sea The Arctic Ocean is the smallest and shallowest of the world's five major oceans. It spans an area of approximately and is known as the coldest of all the oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, a ...

and the lakes of the

Nordic countries The Nordic countries (also known as the Nordics or ''Norden''; literal translation, lit. 'the North') are a geographical and cultural region in Northern Europe and the Atlantic Ocean, North Atlantic. It includes the sovereign states of Denmar ...

Description

''Monoporeia affinis'' measures up to long when fully grown, with two pairs of antennae and one pair of black eyes. The legs arising from the first three segments of the abdomen are expanded basally to form broad plates. ''Monoporeia affinis'' closely resembles another benthic amphipod, '' Pontoporeia femorata'', which can be distinguished from ''M. affinis'' by its light red eyes.

Ecology

''M. affinis'' is one of the Baltic

glacial relict A glacial relict is a population of a cold-adapted species that has been left behind as the range of the species changed after an ice age ended. Glacial relicts are usually found in enclaves "under relatively benign conditions". Examples: *The ...

s. Originally a freshwater species, it also exists in lakes. ''M. affinis'' lives on soft bottoms, sometimes even as densely as 10,000–20,000 but usually hundreds to thousands of individuals per square metre. The amphipod has an important role in

bioturbation Bioturbation is defined as the reworking of soils and sediments by animals or plants. It includes burrowing, ingestion, and defecation of sediment grains. Bioturbating activities have a profound effect on the environment and are thought to be a pr ...

(mixing and oxidating the bottom sediment). ''Monoporeia'' feeds on

phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems. The name comes from the Greek words (), meaning 'plant', and (), meaning 'wanderer' or 'drifter'. Ph ...

and decomposed organic matter sinking onto the bottom. ''M. affinis'' is itself the prey of '' Saduria entomon'', '' Harmothoe sarsi'' (a

polychaete Polychaeta () is a paraphyletic class (biology), class of generally marine invertebrate, marine annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that ...

) and fishes such as

cod Cod is the common name for the demersal fish genus '' Gadus'', belonging to the family Gadidae. Cod is also used as part of the common name for a number of other fish species, and one species that belongs to genus ''Gadus'' is commonly not call ...

herring Herring are forage fish, mostly belonging to the family of Clupeidae. Herring often move in large schools around fishing banks and near the coast, found particularly in shallow, temperate waters of the North Pacific and North Atlantic Oceans, i ...

and the

fourhorn sculpin The fourhorn sculpin (''Myoxocephalus quadricornis'') is a species of fish in the family Cottidae. It is a demersal fish distributed mainly in brackish arctic coastal waters in Canada, Greenland, Russia, and Alaska, and also as a relict in the bo ...

, ''Myoxocephalus quadricornis''. The increasing loss of

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

in the Baltic Sea bottoms – especially in the

Gulf of Finland The Gulf of Finland ( fi, Suomenlahti; et, Soome laht; rus, Фи́нский зали́в, r=Finskiy zaliv, p=ˈfʲinskʲɪj zɐˈlʲif; sv, Finska viken) is the easternmost arm of the Baltic Sea. It extends between Finland to the north and E ...

– has lately been affecting the ''M. affinis'' population, since its eggs and embryos are very sensitive to lack of oxygen. Thus ''M. affinis'' is often used as an

indicator species A bioindicator is any species (an indicator species) or group of species whose function, population, or status can reveal the qualitative status of the environment. The most common indicator species are animals. For example, copepods and other sma ...

of the state bodies of water.

Life cycle

After mating in the autumn and bearing over the winter, the female ''M. affinis'' gives birth to 20–30 offspring, which only happens once during its 2–4 year lifespan.

Taxonomic history

''Monoporeia affinis'' was originally described in the genus ''

Pontoporeia ''Pontoporeia'' is a genus of fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are c ...

'' by Gustaf Lindström in 1855. It was moved to the new genus ''Monoporeia'' by Edward L. Bousfield in 1989, alongside two other species, "''M. microphthalma''" and "''M. gurjanovae''", which are now considered

synonyms A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

of ''M. affinis''.

References

{{Taxonbar, from=Q150318 Gammaridea Crustaceans of the Atlantic Ocean Freshwater crustaceans of Europe Monotypic crustacean genera