MEPS 285:151-156 (2005)  -  doi:10.3354/meps285151

Distribution and densities of the decapod crabPercnon gibbesi, an invasive Grapsidae, in western Mediterranean waters

S. Deudero1,*, A. Frau1, M. Cerda1, H. Hampel2

1Grup d’Oceanografia Interdisciplinar (GOI)-Institut Mediterrani d'Estudis Avançats-CSIC/UIB, Guillem Colom,Campus Universitari, Ctra. de Valldemossa, km 7.5, 07122 Palma de Mallorca, Spain 2Royal Belgian Institute of Natural Sciences, Vautierstraat 27, 1000 Brussels, Belgium

ABSTRACT: Density, population structure and spatial distribution of the invasive crab Percnon gibbesi in western Mediterranean waters were investigated. Densities appeared highest within pebble substrates, reaching up to 3 ind. m-2. Modal length was 20 mm carapace length (CL), with the presence of ovigerous females from 18 mm CL. Maximum densities were observed at 1 m depth. There were significant differences in habitat preference toward boulders of variable size with algal cover not higher than 0.5 cm. Although individuals were highly active during the daytime, activity patterns were highest at sunset. Further studies are required on the biology and ecology of this grapsid crab to better understand the reasons for its population growth along Mediterranean coasts and to ascertain the means of colonization.

KEY WORDS: Percnon gibbesi · Grapsidae · Mediterranean · Alien species

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