Ecological impacts of non-native Pacific oysters (Crassostrea gigas) and management measures for protected areas in Europe

Roger J H Herbert,Steve Fletcher,Clare J Davies,Tasman P Crowe,Caroline Roberts,John Humphreys

doi:10.1007/s10531-016-1209-4

Abstract

Pacific oysters are now one of the most ‘globalised’ marine invertebrates. They dominate bivalve aquaculture production in many regions and wild populations are increasingly becoming established, with potential to displace native species and modify habitats and ecosystems. While some fishing communities may benefit from wild populations, there is now a tension between the continued production of Pacific oysters and risk to biodiversity, which is of particular concern within protected sites. The issue of the Pacific oyster therefore locates at the intersection between two policy areas: one concerning the conservation of protected habitats, the other relating to livelihoods and the socio-economics of coastal aquaculture and fishing communities. To help provide an informed basis for management decisions, we first summarise evidence for ecological impacts of wild Pacific oysters in representative coastal habitats. At local scales, it is clear that establishment of Pacific oysters can significantly alter diversity, community structure and ecosystem processes, with effects varying among habitats and locations and with the density of oysters. Less evidence is available to evaluate regional-scale impacts. A range of management measures have been applied to mitigate negative impacts of wild Pacific oysters and we develop recommendations which are consistent with the scientific evidence and believe compatible with multiple interests. We conclude that all stakeholders must engage in regional decision making to help minimise negative environmental impacts, and promote sustainable industry development.

Highlights

The proliferation of non-native species around the globe is considered one of the most important biosecurity concerns of our modern age (IUCN 2000)
While some fishing communities may benefit from wild populations, there is a tension between the continued production of Pacific oysters and risk to biodiversity, which is of particular concern within protected sites
The issue of the Pacific oyster locates at the intersection between two policy areas: one concerning the conservation of protected habitats, the other relating to livelihoods and the socio-economics of coastal aquaculture and fishing communities

Summary

Introduction

The proliferation of non-native species around the globe is considered one of the most important biosecurity concerns of our modern age (IUCN 2000). Invasive species that have the greatest impact are often ‘ecosystem engineers’ that affect organisms via changes to the physical and chemical environment (Jones et al 1994, 1997; Jones and Gutierrez 2007; Crooks 2009). These species may create, destroy or modify habitats (Crooks 2009; Sousa et al 2009; Padilla 2010; Markert et al 2010; Van der Zee et al 2012). Of considerable importance for coastal economies around the world, the introduction of C. gigas has been very significant in maintaining the oyster fishing and cultivation culture and traditions of communities that have previously relied on native oysters, which in many regions are declining (Goulletquer and Heral 1997; Zu Ermgassen et al 2012; Humphreys et al 2014)

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