a1 Centro Interdisciplinar de Investigação Marinha e Ambiental, Rua dos Bragas 289, 4050-123 Porto, Portugal
a2 Royal Netherlands Institute for Sea Research, PO Box 59, 1790 AB Den Burg Texel, The Netherlands
a3 Departamento de Zoologia–Antropologia, Faculdade de Ciências da Universidade do Porto, Praça. Gomes Teixeira, 4099-002 Porto, Portugal
Morphometry has been used in the investigation of the common shrimp Crangon crangon subpopulation structure at a local scale (100 km) around the UK. In the present study C. crangon populations were sampled over the whole distributional range from northern Norway to the Mediterranean and Black Sea to test whether the same method could be applied to describe subpopulation structure at a much larger scale (1000 km). Spatial variability in morphometric characters was determined by sampling 25 locations across the distributional range. In addition, the temporal variability in morphology was studied at 4 sites (Bodo, Norway; Wadden Sea, The Netherlands; Minho and Lima estuaries, Portugal). Contrary to expectations, temporal variability was observed in three of those sites resulting in an inability to distinguish between populations at the local scale. However, the large scale subdivision of shrimp populations from the Adriatic, Black Sea, Mediterranean and Atlantic were clearly identified. It is concluded that, while there are clear morphological differences between major zoogeographical zones, at a local scale, subpopulations frequently cannot be identified because of individual variability.
(Received June 25 2007)
(Accepted May 23 2008)
(Online publication October 31 2008)