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Marine Ecology Progress Series

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MEPS 430:235-240 (2011)  -  DOI:

Population demographics of native and newly ­invasive populations of the green crab Carcinus maenas

Iain J. McGaw1,2,*, Timothy C. Edgell3, Michel J. Kaiser4

1Ocean Sciences Centre, 1 Marine Lab Road, Memorial University, St John’s, Newfoundland A1C 5S7, Canada,
2Bamfield Marine Sciences Centre, 100 Pachena Road, Bamfield, British Columbia V0R 1B0, Canada
3LGL Limited Environmental Research Associates, 9768 Second Street, Sidney, British Columbia V8L 3Y8, Canada
4School of Ocean Sciences, College of Natural Sciences, Bangor University, Menai Bridge, Anglesey LL59 2AB, UK

ABSTRACT: Green crabs Carcinus maenas (L.) are native to north-western Europe, but have been spread globally by humans during the last 200 yr. Reproductively viable populations have been present for <10 yr in British Columbia, Canada. In the present study, C. maenas were collected from 2 geographically separated locations, Anglesey (UK) and British Columbia (Canada), to compare body-size and colour distributions between native and newly invasive populations. Crabs were captured using baited traps and collected by hand at both intertidal and shallow subtidal elevations. Crabs from British Columbia were significantly larger than those from Europe. The largest male, 101.1 mm, and the largest female, of 85.4 mm carapace width, were both captured in British Columbia. The native populations showed a higher frequency of red-coloured crabs than the introduced population, which consisted predominately of green-coloured male crabs. Green-coloured integuments are typical of individuals in the early stages of intermoult. Accordingly, the high frequency of large, green-coloured C. maenas in British Columbia suggests that individuals in this population have an atypically high growth rate and achieve a larger body size and, hence, potentially greater fecundity. Moreover, the scarcity of small C. maenas in British Columbia may indicate that the existing population comprises only the first or second generation of recruits. The observed differences in body size and colour distribution are perhaps indicative of release from an as yet undetermined growth-limiting factor (possibly parasites) and provide a unique opportunity to study the dynamics of a newly invasive population as it recruits and matures.

KEY WORDS: Carcinus maenas · Crab · Distribution · Colour form · Moult stage

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Cite this article as: McGaw IJ, Edgell TC, Kaiser MJ (2011) Population demographics of native and newly ­invasive populations of the green crab Carcinus maenas. Mar Ecol Prog Ser 430:235-240.

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