The Asian date mussel (
Arcuatula senhousia) is one of the most globally widespread non-native marine species which is invasive throughout much of its introduced range. Recently recorded in the United Kingdom (UK) for the first time,
A. senhousia may be on the cusp of significantly expanding its range across the UK and Northern Europe. Understanding the risks and impacts that
A. senhousia poses to the environment and economies is therefore urgently required. Determining
A. senhousia’s biology and ecology in the UK is key to effective risk assessment, however significant knowledge gaps remain, particularly with regards to
A. senhousia populations in the subtidal. Dredge surveys combined with morphometric and reproductive analyses confirmed
A. senhousia’s population dynamics in the subtidal, revealing low densities (0-0.91 ind. m-2) within a 0.08 km2 site. However, the analysis of a long-term dataset of benthic community composition within the same area revealed populations that have been consistently detected over a period of 11 years within commercially and ecologically important habitats. Using this same dataset, a generalised linear mixed model (GLMM) determined a positive but insignificant effect (p = 0.054) of increasingly fine sediments on
A. senhousia presence. Associations between
A. senhousia and the bivalves
Mytilus edulis, Cerastoderma edule and
Ruditapes philippinarum (important fishery species on the south coast of the UK) were also explored using the GLMM but were not statistically significant. Nonetheless,
M. edulis, C. edule and
R. philippinarum occurred in samples that also contained
A. senhousia, at rates of 33%, 25% and 50%, respectively. An extended summer reproduction period (June to October) may overlap with other keystone bivalves, creating substrate competition if densities increase, which has ecological and economic implications. Feeding rate experiments, using the indirect clearance rate method, evidenced that
A. senhousia’s clearance rate was 2-26 x higher (n = 6) than that of other suspension-feeding bivalves when standardised per g of dry tissue.
Arcuatula senhousia’s invasion of the UK could therefore cause food competition and alter benthic and plankton communities. Together, these data confirm that
A. senhousia currently poses a potential threat to the UK’s, and by extension Northern Europe’s, ecosystem goods and services. Finally, species distribution modelling indicates that this threat is likely to increase in the UK and Northern Europe as climate change increases habitat suitability for
A. senhousia, from “moderate” to “high”. In light of this, the results of thesis have been used to recommend vital updates to the UK’s current risk assessment and to identify potential monitoring and management actions.
| Date of Award | 29 Feb 2024 |
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| Original language | English |
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| Awarding Institution | |
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| Supervisor | Gordon Watson (Supervisor), Paul Stebbing (Supervisor), Steve Mitchell (Supervisor) & Hannah J. Tidbury (Supervisor) |
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