TY - JOUR
T1 - Resilience and elasticity of intertidal communities in response to harvesting of the alien mussel Mytilus galloprovincialis
AU - Robinson, Tamara B.
AU - Branch, George M.
AU - Griffiths, Charles L.
AU - Govender, Anesh
N1 - Funding Information:
We would like to thank the National Research Foundation and the Department of Environmental Affairs and Tourism: Marine and Coastal Management Branch for funding this project through the Sea and the Coast Programme II. Additionally, the Marine Biology Research Centre at the University of Cape Town and the Andrew Mellon Foundation provided much appreciated financial support. Paula de Coito, Eleanor Yeld, and Hannah Medd are gratefully acknowledged for their help in the field. [SS]
PY - 2008/1/18
Y1 - 2008/1/18
N2 - Besides the direct impacts of exploitation on target species, indirect effects on non-target species are unavoidable and find expression in changes in community structure. We quantified the effects of experimental harvesting of Mytilus galloprovincialis on intertidal communities on the South African west coast. In the mid- and low-shore, four months of harvesting at intensities greater than F = 0.3 and F = 0.6 respectively, resulted in significant changes in community composition. These changes were driven by progressively greater spatial dominance by the macroalgae Cladophora flagelliformis, Porphyra capensis and Ulva species as harvesting intensity increased. Four months after cessation of harvesting, community structure had not recovered and even areas subjected to as little as F = 0.3 supported significantly altered communities in both zones. The fact that substantial community changes were induced by even low-intensity exploitation is indicative of low resilience to harvesting. The densities and cover of the dominant taxa returned to a pre-harvest state 16 months after the cessation of harvesting, but multivariate analyses indicated that the overall community composition required 32 months for Cover Letter full recovery. Although these communities displayed elasticity within three years, it is recommended that should a M. galloprovincialis fishery be established in the region, harvesting be implemented at a maximum intensity of F = 0.3. This approach would maximise yields and protect associated intertidal communities.
AB - Besides the direct impacts of exploitation on target species, indirect effects on non-target species are unavoidable and find expression in changes in community structure. We quantified the effects of experimental harvesting of Mytilus galloprovincialis on intertidal communities on the South African west coast. In the mid- and low-shore, four months of harvesting at intensities greater than F = 0.3 and F = 0.6 respectively, resulted in significant changes in community composition. These changes were driven by progressively greater spatial dominance by the macroalgae Cladophora flagelliformis, Porphyra capensis and Ulva species as harvesting intensity increased. Four months after cessation of harvesting, community structure had not recovered and even areas subjected to as little as F = 0.3 supported significantly altered communities in both zones. The fact that substantial community changes were induced by even low-intensity exploitation is indicative of low resilience to harvesting. The densities and cover of the dominant taxa returned to a pre-harvest state 16 months after the cessation of harvesting, but multivariate analyses indicated that the overall community composition required 32 months for Cover Letter full recovery. Although these communities displayed elasticity within three years, it is recommended that should a M. galloprovincialis fishery be established in the region, harvesting be implemented at a maximum intensity of F = 0.3. This approach would maximise yields and protect associated intertidal communities.
KW - Alien species
KW - Community effects
KW - Harvesting
KW - Mussel
KW - Mytilus galloprovincialis
KW - South Africa
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U2 - 10.1016/j.jembe.2007.11.002
DO - 10.1016/j.jembe.2007.11.002
M3 - Article
AN - SCOPUS:38049050723
SN - 0022-0981
VL - 354
SP - 169
EP - 181
JO - Journal of Experimental Marine Biology and Ecology
JF - Journal of Experimental Marine Biology and Ecology
IS - 2
ER -