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Marine Ecology Progress Series

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MEPS 552:145-158 (2016)  -  DOI:

Paleo-ecological analyses to assess long-term environmental effects of pearl farming in Western Australia

Dongyan Liu1,*, Yajun Peng1,2, John K. Keesing3,4, Yujue Wang1, Pierre Richard5

1Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, 264003 Yantai, Shandong, PR China
2University of the Chinese Academy of Sciences, 100049 Beijing, PR China
3CSIRO Oceans and Atmosphere, Private Bag 5, Wembley 6913, Australia
4The Western Australian Marine Science Institution, Perth, Australia
5Littoral, Environment et Sociétés, UMR 7266 CNRS-Université de La Rochelle, 2 rue Olympe de Gouges, 17000 La Rochelle, France
*Corresponding author:

ABSTRACT: Small environmental disturbances accumulating over a long period of time may cause a regime shift in marine ecosystems, particularly in sensitive oligotrophic waters. Pearl oyster aquaculture, which has a 50 yr history in Australia, has been regarded as an anthropogenic activity with low environmental risk. To assess the long-term environmental effects of pearl oyster farming, sediment cores taken in Cygnet Bay, Western Australia, were used to reconstruct environmental processes covering an approximately 90 yr period. Biogeochemical parameters in sediment cores from inside and outside a pearl farming area displayed contrasting characteristics over time. Total organic carbon, total nitrogen, biogenic silica (BSi), and fine-grained sediment at the farming site displayed significant increases with the expansion of oyster stocking. In contrast, only small variations in response to climatic signals (rainfall and temperature) occurred over time in the cores outside the farm. The variation in the C:N ratio, δ13C and δ15N ranges over time suggested that increased organic matter was mainly contributed by autochthonous sources rather than terrestrial input. The sequential t-test for a regime shift detected approximately 2- to 3-fold increases in organic matter, 1- to 5-fold increases in silt proportion and 2- to 5-fold increases in BSi concentrations after pearl oyster farming, in contrast to the control site. The rapid development of modern long-line culture since the late 1980s is presumed to have been the dominant driver of environmental changes in sediments. The results provide insight into the magnitude of environmental change which can occur over decades as a result of even minimal anthropogenic activity.

KEY WORDS: Pearl oyster farming · Paleo-ecology · Sediment cores · Biogenic silica · Cygnet Bay · Western Australia

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Cite this article as: Liu D, Peng Y, Keesing JK, Wang Y, Richard P (2016) Paleo-ecological analyses to assess long-term environmental effects of pearl farming in Western Australia. Mar Ecol Prog Ser 552:145-158.

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