Population dynamics of the invasive Pacific oyster Crassostrea gigas during the early stages of an outbreak in the Wadden Sea (Germany) |
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Authors: | Andreas Schmidt Achim Wehrmann Sabine Dittmann |
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Institution: | (1) Senckenberg Institute, Südstrand 40, 26382 Wilhelmshaven, Germany;(2) School of Biological Sciences, Flinders University of South Australia, GPO Box 2100, Adelaide, SA, 5001, Australia |
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Abstract: | Since the late 1990s, the Pacific oyster (Crassostrea gigas) has spread into the East Frisian Wadden Sea (Germany). This invasion provided an opportunity to study the population dynamics
and the patterns of spread during the initial bioinvasion process. With its source area in The Netherlands, the bioinvasion
continues in an eastward direction, as documented by a gradient of high abundances in the west and low abundances in the east
during the first study year. One year later, abundances of the Pacific oyster were more heterogenic and differed between adjacent
tidal basins. The increase in population sizes at all study sites was very high, reaching levels similar to native occurrence
populations. The growth constant (K) varied between 0.300 and 0.990 year−1. The mussel bed with the highest densities had a mean abundance of >300 ind. m−2, and a maximum of 1,460 ind. m−2. Furthermore, the bioinvasion was facilitated by a low mortality (Z) found for populations between 0.5 and 1.5 years old (Z = 0.03–0.13 year−1). At present, Pacific oysters are well established at several locations in the East Frisian Wadden Sea and may become with
these reproductive potential self-sustaining populations. |
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Keywords: | Bioinvasion Population growth Mortality Larvae dispersal Non-indigenous |
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