Population zoogeography of brown shrimp Crangon crangon along its distributional range based on morphometric characters

Morphometry has been used in the investigation of the common shrimp Crangon crangon subpopulation structure at a local scale (too km) around the UK. In the present study C. crangon populations were sampled over the whole distributional range front 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 kin). 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.