SHORT COMMUNICATION. Rapid establishment of the alien crab Rhithropanopeus harrisii (Gould) in the Gulf of Riga

Abstract

The aim of this paper was to report the arrival and rapid colonization of the nektobenthic crustacean Rhithropanopeus harrisii in the shallow north-eastern Gulf of Riga. The crab was found for the first time from the Estonian coastal sea in Pärnu Bay in August 2011. In 2012, during targeted sampling efforts, different life-history stages of the species (larvae, juveniles, and adults) were observed all over Pärnu Bay with some sporadic findings at the open coast of the Gulf of Riga. These observations, together with a successful breeding, confirm that R. harrisii is established in the study area. Provided the high density of R. harrisii and the lack of such functional trait in the study area and in the north-eastern Baltic Sea range in general, this invasion is likely to cause significant repercussions on the structure and functioning of soft-and hard-bottom benthic macrophyte and invertebrate communities in the near future.