Non-native crab Rhithropanopeus harrisii (Gould, 1984) – a new component of the benthic communities in the Gulf of Gdańsk (southern Baltic Sea)*

The aim of this study was to determine the occurrence, spatial distribution and abundance pattern of the Harris mud crab Rhithropanopeus harrisii in the Gulf of Gdańsk (southern Baltic Sea). Between 2006 and 2010, this species was found at 69 out of 129 sampling stations, at depths from 0 to 20 m. Two main aggregations of the Harris mud crab were established: (1) in Puck Bay (max. density 19 indiv. 100 m− 2) and (2) in the Gdynia and Sopot area (max. density 5 indiv. 100 m− 2). 920 specimens were collected during the whole sampling period: 150 juveniles, 370 females and 400 males. The minimum measured carapace width was 1.96 mm, the maximum 21.40 mm (mean 9.03 ± 4.11 mm).