Monoporeia

Monoporeia affinis (synonym: Pontoporeia affinis ) is a freshwater shrimp from the family of Pontoporeiidae, which is very common in the Baltic Sea. He is, however, also be found in fresh water of the Scandinavian lakes. Monoporeia affinis is the only species of the genus Monoporeia.

The amphipod is considered a relic of the last ice age. As the Scandinavian ice sheet began to melt, this originally emigrated in freshwater -based nature of the area of the Barents Sea in the Baltic Sea a. Other deposits are found in the Arctic.

Features

Monoporeia affinis is up to 8 mm long. The body is laterally flattened and yellowish to white. The black eyes distinguish it from the closely related Pontoporeia femorata, which has bright red eyes and does not occur in brackish water. Monoporeia affinis has two pairs of short, powerful antennas. The pereiopods are strong, furnished with bristles and widened in the soil for digging.

Habitat

Monoporeia affinis colonized the muddy substrate on the bottom of the Baltic Sea in huge quantities. It often 10,000 to 20,000 individuals per square meter were found, on average, there are several thousand. The amphipod is associated with the Baltic clam Macoma balthica Platt and forms with this most of the macrobenthos of the Baltic Sea. It feeds mainly on phytoplankton and detritus falling to the ground, but also affects the populations of the Baltic platform shell after the mussel larvae have fixed on the ground. The amphipod can with its claws crack the shells, but he can also by digging tube-like structures hinder the settlement of mussels. Only when the larvae have become greater than 1 mm, survive the attacks of the amphipods.

Monoporeia affinis is the main food of giant isopods ( Saduria entomon ), the predatory polychaete Harmonthoe sarsi and the cod.