High mortality of Pacific oysters in a cold winter in the North-Frisian Wadden Sea

Büttger, Heike; Nehls, Georg; Witte, Sophia

doi:10.1007/s10152-011-0272-1

Cited by 37 publications

(22 citation statements)

References 13 publications

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“…Comparing autumn and spring abundances, Büttger et al (2011) estimated winter mortality to about 90% with all size classes of C. gigas affected. However, most shells remained in place and long-lasting effects on the oyster population were not to be expected.…”

Section: Discussionmentioning

confidence: 99%

Invasion trajectory of Pacific oysters in the northern Wadden Sea

et al. 2017

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Invasion trajectories of introduced alien species usually begin with a long establishment phase of low abundance, often followed by exponential expansion and subsequent adjustment phases. We review the first 26 years of feral Pacific oysters Crassostrea gigas around the island of Sylt in the Wadden Sea (North Sea, NE Atlantic), and reveal causal conditions for the invasion phases. Sea-based oyster farming with repeated introductions made establishment of feral oysters almost inevitable. Beds of mussels Mytilus edulis on mud flats offered firm substrate for attachment and ideal growth conditions around low tide level. C. gigas mapped on to the spatial pattern of mussel beds. During the 1990s, cold summers often hampered recruitment and abundances remained low but oyster longevity secured persistence. Since the 2000s, summers were often warmer and recruitment more regular. Young oysters attached to adult oysters and abundances of >1000 m−2 were achieved. However, peak abundance was followed by recruitment failure. The population declined and then was also struck by ice winters causing high mortality. Recovery was fast (>2000 m−2) but then recruitment failed again. We expect adjustment phase will proceed with mean abundance of about 1000 m−2 but density-dependent (e.g., diseases) and density-independent (e.g., weather anomalies) events causing strong fluctuations. With continued global warming, feral C. gigas at the current invasion fronts in British estuaries and Scandinavian fjords may show similar adjustment trajectories as observed in the northern Wadden Sea, and also other marine introductions may follow the invasion trajectory of Pacific oysters.

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Section: Discussionmentioning

confidence: 99%

Invasion trajectory of Pacific oysters in the northern Wadden Sea

et al. 2017

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“…Secondly, a dramatic increase has taken place since 2002 in the abundance and biomass of 2 invasive species namely the Pacific oyster Crassostrea gigas (Büttger et al 2010) and the balanoid Austrominius modestus (Table 1). The biomass of these 2 invasive species constituted about 27% of the system's total biomass in 2007, but only 1.3% in 2010 (Table 1) (Büttger et al 2011). Indeed, the decrease in bivalve larvae since 2007 (Table 3) gives a crude hint that low recruitment and spat fall could well have been the cause of oyster decline from 2007 to 2010 (Fig.…”

Section: General System Characteristicsmentioning

confidence: 99%

Effect of invasive species on the structure and function of the Sylt-Rømø Bight ecosystem, northern Wadden Sea, over three time periods

Baird¹,

Asmus²,

Asmus³

2012

Mar. Ecol. Prog. Ser.

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, respectively, in 2010. Reasons for the increases in oysters and A. modestus are related to climate change which favored strong recruitment of the invasive species during unseasonably warm summers, and the subsequent decline to weak recruitment of the invasive species and an unseasonably cold 2009/2010 winter. We used ecological network analysis (ENA) to quantify ecosystem structure and function through analyses of energy (or carbon) transfer between living and non-living compartments in each of the 3 network models. Results from ENA show an increase in most of the system attributes, but a decline in number of cycles, the trophic efficiency, the ascendency ratios, and relative redundancy from 1995 to 2007; these are ascribed to the impact of the invasive species on system organization and function. Following the dramatic decline of the invasive species from 2007 to 2010 most of the system attributes decreased. The variance in the biomass and associated flows of other compartments in addition to that of the invasive species has also played a role in the changes in system attributes and function.

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“…The invasion of Pacific oysters into the Wadden Sea part of the North Sea originated from aquaculture activities in the 1990s [21], and today Pacific oysters locally represent the dominant epibenthic bivalve species [22]. Oyster populations in the northern and southern parts of the Wadden Sea stem from two genetically distinct invasion sources [23].…”

Section: Introductionmentioning

confidence: 99%

Disturbance induced decoupling between host genetics and composition of the associated microbiome

et al. 2013

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BackgroundStudies of oyster microbiomes have revealed that a limited number of microbes, including pathogens, can dominate microbial communities in host tissues such as gills and gut. Much of the bacterial diversity however remains underexplored and unexplained, although environmental conditions and host genetics have been implicated. We used 454 next generation 16S rRNA amplicon sequencing of individually tagged PCR reactions to explore the diversity of bacterial communities in gill tissue of the invasive Pacific oyster Crassostrea gigas stemming from genetically differentiated beds under ambient outdoor conditions and after a multifaceted disturbance treatment imposing stress on the host.ResultsWhile the gill associated microbial communities in oysters were dominated by few abundant taxa (i.e. Sphingomonas, Mycoplasma) the distribution of rare bacterial groups correlated to relatedness between the hosts under ambient conditions. Exposing the host to disturbance broke apart this relationship by removing rare phylotypes thereby reducing overall microbial diversity. Shifts in the microbiome composition in response to stress did not result in a net increase in genera known to contain potentially pathogenic strains.ConclusionThe decrease in microbial diversity and the disassociation between population genetic structure of the hosts and their associated microbiome suggest that disturbance (i.e. stress) may play a significant role for the assembly of the natural microbiome. Such community shifts may in turn also feed back on the course of disease and the occurrence of mass mortality events in oyster populations.

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High mortality of Pacific oysters in a cold winter in the North-Frisian Wadden Sea

Cited by 37 publications

References 13 publications

Invasion trajectory of Pacific oysters in the northern Wadden Sea

Invasion trajectory of Pacific oysters in the northern Wadden Sea

Effect of invasive species on the structure and function of the Sylt-Rømø Bight ecosystem, northern Wadden Sea, over three time periods

Disturbance induced decoupling between host genetics and composition of the associated microbiome

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