Feasibility study on culturing Pacific oysters in the Wadden Sea of Schleswig-Holstein

Abstract With globally growing aquaculture activities, the co-introduction of parasites alongside large-scale movements of commercial species poses an increasing risk for marine ecosystems. Here, we present the first record of the shell-boring polychaete Polydora websteri Hartman in Loosanoff and Engle, 1943 in invasive Pacific oysters Crassostrea (Magallana) gigas (Thunberg, 1793) in the European Atlantic Ocean. In October 2014, mud blisters in the shells of wild Pacific oysters and specimens of a spionid polychaete were observed in close proximity to a commercial oyster farm at the island of Sylt (Germany) in the European Wadden Sea. Subsequent investigations indicated that these blisters only occurred near the farm and that no other mollusc species were affected. Morphological and molecular analysis identified the polychaete as Polydora websteri, a species that nowadays widely occurs around the globe, but likely is native to the Asian Pacific. Later sampling activities detected P. websteri also at other locations around Sylt as well as in the Dutch part of the Wadden Sea at the island of Texel. The number of polychaetes in the oysters was, however, relatively low and mostly below 10 individuals per oyster. Together, this evidence suggests that P. websteri is currently extending its range. As the introduction of P. websteri may have severe ecological and economic implications, this study aims to alert others to look for P. websteri at Western European coasts within farmed or wild Pacific oysters to further document its spread.

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Low mortality rates of juvenile Pacific oysters in the German Wadden Sea are characteristic for invasive species: a reply to Beukema and Dekker

Helgoland Marine Research ◽

10.1007/s10152-009-0170-y ◽

2009 ◽

Vol 64 (1) ◽

pp. 71-73 ◽

Cited By ~ 2

Author(s):

A. Schmidt ◽

A. Wehrmann ◽

S. Dittmann

Keyword(s):

Invasive Species ◽

Wadden Sea ◽

Mortality Rates ◽

Pacific Oysters

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Heading northward to Scandinavia: Undaria pinnatifida in the northern Wadden Sea

Botanica Marina ◽

10.1515/bot-2017-0128 ◽

2018 ◽

Vol 61 (4) ◽

pp. 365-371 ◽

Cited By ~ 2

Author(s):

Jessica Schiller ◽

Dagmar Lackschewitz ◽

Christian Buschbaum ◽

Karsten Reise ◽

Shaojun Pang ◽

...

Keyword(s):

North Sea ◽

Wadden Sea ◽

Undaria Pinnatifida ◽

Atlantic Coast ◽

The North ◽

Pacific Oysters ◽

The North Sea ◽

New Generation ◽

Thallus Length ◽

Natural Means

Abstract The kelp Undaria pinnatifida, native to East Asian shores, was unintentionally introduced with Pacific oysters into the Mediterranean in 1971. Intentional introduction from there to the French Atlantic coast 12 years later led to a gradual spread to the British Isles and the North Sea. Here, we report on the northernmost established population in continental Europe, and suggest a further spread into Scandinavian waters to be almost inevitable. In 2016, several thalli were found washed ashore at the eastern side of the island of Sylt in the northern Wadden Sea (German Bight, Eastern North Sea). Most specimens bore fertile sporophylls and thallus lengths of >1 m were common. In June 2017, 91 sporophytes were found attached to a mixed bed of Pacific oysters and native blue mussels, located just below low tide level in a moderately sheltered position. Mean thallus length was 0.2 m and the longest 0.7 m. Most had distinctive sporophylls and released spores in the laboratory. From sporophylls collected in the previous year, we successfully reared a new generation, demonstrating the kelp’s potential for further spread by natural means or human vectors.

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High survival and growth rates of introduced Pacific oysters may cause restrictions on habitat use by native mussels in the Wadden Sea

Journal of Experimental Marine Biology and Ecology ◽

10.1016/j.jembe.2005.07.012 ◽

2006 ◽

Vol 328 (2) ◽

pp. 211-227 ◽

Cited By ~ 63

Author(s):

Susanne Diederich

Keyword(s):

Habitat Use ◽

Growth Rates ◽

Wadden Sea ◽

High Survival ◽

Pacific Oysters ◽

Survival And Growth ◽

Native Mussels

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Extraordinarily low mortality rates reported in juvenile Pacific oysters in the German Wadden Sea

Helgoland Marine Research ◽

10.1007/s10152-009-0169-4 ◽

2009 ◽

Vol 64 (1) ◽

pp. 69-70 ◽

Cited By ~ 2

Author(s):

J. J. Beukema ◽

R. Dekker

Keyword(s):

Wadden Sea ◽

Mortality Rates ◽

Pacific Oysters

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Prey preferences, consumption rates and predation effects of Asian shore crabs (Hemigrapsus takanoi) in comparison to native shore crabs (Carcinus maenas) in northwestern Europe

Marine Biodiversity ◽

10.1007/s12526-021-01207-7 ◽

2021 ◽

Vol 51 (5) ◽

Author(s):

Annika Cornelius ◽

Katerina Wagner ◽

Christian Buschbaum

Keyword(s):

Feeding Behavior ◽

Wadden Sea ◽

Feeding Habits ◽

Carcinus Maenas ◽

Shore Crab ◽

Crab Species ◽

Blue Mussels ◽

Pacific Oysters ◽

Shore Crabs ◽

Consumption Rates

AbstractThe Asian brush-clawed shore crab Hemigrapsus takanoi was introduced to the northern Wadden Sea (southeastern North Sea) in 2009 and now represents one of the most abundant brachyuran crab species. Abundance studies revealed an increase of mean crab densities on mixed reefs of native blue mussels (Mytilus edulis) and Pacific oysters (Magallana gigas) from 18 individuals m−2 in 2011 to 216 individuals m−2 in 2020. Despite its current high densities only little is known about the feeding habits of H. takanoi, its effects on prey populations and on the associated community in the newly invaded habitat. We summarize results of individual field and laboratory experiments that were conducted to assess feeding habits and consumption effects caused by Asian brush-clawed shore crabs and, additionally, compare the feeding ecology of H. takanoi with the one of the native shore crab Carcinus maenas. Field experiments manipulating crab densities revealed that both crab species affected the recruitment success of blue mussels, Pacific oysters and Australian barnacles (Austrominius modestus) with highest number of recruits at crab exclusion. However, endobenthic polychaetes within the reefs were differently affected. Only the native C. maenas caused a significant reduction in polychaete densities, whereas the introduced H. takanoi had no effect. Additional comparative laboratory studies revealed that single C. maenas consume more juvenile blue mussels than Asian brush-clawed shore crabs of the same size class. When offering amphipods as a mobile prey species, we found the same pattern with higher consumption rates by C. maenas than by H. takanoi. For Asian but not for native shore crabs, we detected a sex-dependent feeding behavior with male H. takanoi preferring blue mussels, while females consumed more amphipods. Considering mean crab densities and feeding behavior, our results suggest that despite lower consumption rates of single crabs, Asian brush-clawed shore crabs can cause stronger impacts on prey organisms than the native C. maenas, because H. takanoi exceeds their densities manifold. A strong impact of the invader on prey populations is supported by low amphipod occurrence at sites where H. takanoi density is high in the study area. Thus, the introduced Asian brush-clawed shore crab is an additional consumer with significant effects on the associated community of mixed reefs of mussels and oysters in the Wadden Sea.

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