Saduria entomon (Linnaeus 1758), Skorv (Crustacea) 

Compiled by: Fritz Gosselck, Germany

1. Description / Ecological demands / Autecology

This big isopod species (up to 84 mm in length) is restricted to deep cold water zones in the Baltic Sea and tolerates reduced salinities from 35 psu down to 0 psu. Skorv lives on varying types of bottoms, e.g. sand, gravel and mud. It is one of the Baltic glacial relicts. Skorv is a scavenger and predator, capable of swimming, that feeds on other benthic animals, such as Monoporeia affinis, Macoma balthica and chironomid larvae. Skorv is an important food source for cod.

2. Distribution

Saduria entomon is distributed over the Baltic Sea, but not in the Belt Sea. In the western Baltic Sea (Arkona Basin, Bornholm Basin) its distribution is restricted to areas deeper than 10 m (needs cold water), whereas in the eastern and northern sea areas it is found also in the surface waters.

3. Importance

Saduria entomon is an endemic species to the Baltic Sea.

4. Status of threat

S. entomon is red-listed in the German part of the Baltic Sea as “vulnerable”.

5. Threat factors

The loss of oxygen in the Baltic Sea bottoms has caused decline of the S. entomon population. Reduction of nutrient loading hence improves the populations of skorv.

6. References

Andersin A.B., J. Lassig, L. Parkkonen and H. Sandler 1978: Lomg-term fluctuations of the soft bottom macrofauna in the deep areas of the Gulf of Bothnia 1954-1974; with special reference to Pontoporeia affinis Lindström (Amphipoda). Finnish marine Research, 244: 137-144.

Gärdenfors U. (ed.) 2000: Rödlistade arter i Sverige 2000 – The 2000 Red List of Swedish Species. Swedish Species Information Centre, Uppsala.

Gosselck F., G. Arlt, A. Bick, R. Boensch, J. Kube, V. Schroeren & J. Voss 1996: Rote Listen und Artenlisten der Tiere und Pflanzen des deutschen Küstenbereichs der Ostsee. - In Merck& von Nordheim (Hrsg.): BfN, Bonn-Bad Godesberg, Schriftenreihe für Landschaftspflege und Naturschutz 48: 1-108.

Lopez G. & R. Elmgren 1989: Feeding depth and organic absorption for the deposit-feeding benthic amphipods Pontoporeia affinis and Pontoporeia femorata. Limnol. Oceanogr. 34 (6): 982-991.

HELCOM 1990: Third periodic assessment of the state of the marine environment of the Baltic Sea, 1989-1993. Background document. Baltic Sea Environment Proceedings 64 B: 252 pp.

Olafson E. & Elmgren E. 1991: Effects of biological disturbance by benthic amphipods Monoporeia affinis on meiobenthic communities structure: a laboratory approach. Mar. Ecol. Prog. Ser. 74: 99-107.

Petersen G. H., 1996: En truet biotop I Østersøen. Flora og Fauna, 4: 197-200, Århus. Petersen G. H. & Russel, P.J.C. 1971: Cardium hauniense nov. sp. a new brackish water bivalve from the Baltic. Ophelia 9: 11-13.

von Weber M. & F. Gosselck 1993: Die Notwendigkeit marinen Artenschutzes am Beispiel der Herzmuschel Cerastobyssum hauniense (Petersen & Russel, 1971) aus dem Salzhaff (Wismarer Bucht, Westl. Ostsee). Naturschutzarbeit in Mecklenburg-Vorpommern, 36: 2: 28-37.

Wolowicz M. & K. Wiktor 1975: Charakteristics of the Cardium hauniense (Petersen & Russel, 1971) population in the Puck Bay proper. In: IV Symp. Baltic Mar. Biol. Gdansk: 266-272.