Monoporeia

Monoporeia affinis
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Crustacea
Class:	Malacostraca
Order:	Amphipoda
Suborder:	Gammaridea
Family:	Pontoporeiidae
Genus:	Monoporeia Bousfield, 1989
Species:	M. affinis
Binomial name
Monoporeia affinis (Lindström, 1855)
Synonyms [1]
Pontopareia affinis Lindström, 1855

Monoporeia affinis, formerly referred to as Pontoporeia affinis (Greek: pontos = Pontus / Black Sea; poreia = to travel), is a small, yellowish benthic amphipod living in the Baltic Sea, the Arctic Sea and the lakes of the Nordic Countries.

Description

Monoporeia affinis measures up to 8 millimetres (0.31 in) long when fully grown, with two pairs of antennae and one pair of black eyes.^[2] The legs arising from the first three segments of the abdomen are expanded basally to form broad plates.^[2] Monoporeia affinis closely resembles another benthic amphipod, Pontoporeia femorata, which can be distinguished from M. affinis by its light red eyes.^[2]

Ecology

M. affinis is one of the Baltic glacial relicts. 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.^[3] The amphipod has an important role in bioturbation (mixing and oxidating the bottom sediment). Monoporeia feeds on phytoplankton and decomposed organic matter sinking onto the bottom. M. affinis is itself the prey of Saduria entomon, Harmothoe sarsi (a polychaete) and cod. The increasing loss of oxygen in the Baltic Sea bottoms – especially in the Gulf of Finland – 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 of the state of the Baltic Sea.

Life cycle

After mating in the fall 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.^[3]

References

1. ^ Jim Lowry, Mark Costello & Denise Bellan-Santini (2011). "Monoporeia affinis (Lindström, 1855)". In J. Lowry. World Amphipoda database. World Register of Marine Species. http://www.marinespecies.org/aphia.php?p=taxdetails&id=103077. Retrieved June 7, 2011. 
2. ^ ^{a b c} "Amphipod Monoporeia affinis". Aquascope. Tjärnö Marine Biological Laboratory. 2000. http://www.vattenkikaren.gu.se/fakta/arter/crustace/amphipod/monoaffi/monoafe.html. Retrieved May 7, 2005. 
3. ^ ^{a b} "Valkokatkat / Itämeri-sanakirja" (in Finnish). The Baltic Sea Portal. Finnish Institute of Marine Research. January 13, 2005. Archived from the original on February 5, 2007. http://web.archive.org/web/20070205162457/http://www.fimr.fi/fi/itamerikanta/sanasto/valkokatkat.html. Retrieved May 7, 2005.