Benthic assemblages associated with native and non-native oysters are similar

Abstract

Invasive species can impact native species and alter assemblage structure, which affects associated ecosystem functioning. The pervasive Pacific oyster, Crassostrea gigas, has been shown to affect the diversity and composition of many host ecosystems. We tested for effects of the presence of the invasive C. gigas on native assemblages by comparing them directly to assemblages associated with the declining native European oyster, Ostrea edulis. The presence of both oyster species was manipulated in intertidal and subtidal habitats and reefs were constructed at horizontal and vertical orientation to the substratum. After 12 months, species diversity and benthic assemblage structure between assemblages with C. gigas and O. edulis were similar, but differed between habitats and orientation, suggesting that both oyster species were functionally similar in terms of biodiversity facilitation. These findings support evidence, that non-native species could play an important role in maintaining biodiversity in systems with declining populations of native species.

Return of the native facilitated by the invasive? Population composition, substrate preferences and epibenthic species richness of a recently discovered shellfish reef with native European flat oysters (Ostrea edulis) in the North Sea

“…These results support the value of restoring O. edulis reefs for biodiversity in general and specific conservation goals in the North Sea. Although benthic assemblages associated with native and non-native oysters can be similar (Zwerschke et al 2016), their net biomass and biodiversity is expected to increase when restoring native oysters due to the different spatial distribution of both oysters. In contrast to native oysters, invasive oysters are restricted to a coastal (shallow) habitat (personal observation authors), and therefore only native oysters are available for restoration of oyster reefs in deeper offshore habitats.…”

Offshore Wind Farms as Potential Locations for Flat Oyster (Ostrea edulis) Restoration in the Dutch North Sea

“…Despite this, some mechanisms are assumed to be generic for both species and environments. [24], for example, demonstrated that the species facilitations function of the intertidal native European oyster bed is similar to the invasive Pacific oyster (C. gigas) reefs. Beds of the European oyster Ostrea edulis function as a habitat for many species (Figure 1).…”

Wild Pacific oyster Magallana gigas (Thunberg, 1793) populations in Romanian Black Sea waters – friend or foe?

“…However, there are signs of increased biodiversity associated with non-native Pacific oyster reefs in the Oosterchelde estuary, Netherlands (van Broekhoven 2005). Also, relatively short-term studies have shown no discrepancy between associated communities of native O. edulis and non-native M. gigas populations in different locations (Zwerschke et al 2016), while studies on sympatric populations of O. edulis and M. gigas over a longer period of time revealed significant differences between associated epibiota (Guy et al 2018). In the case of M. gigas populations established in the Strait of Georgia, Canada, though, the Pacific oyster has occupied an ecosystem niche that was available at the time of introduction, and offered a very good substrate for native barnacle species (Ruesink et al 2005).…”