Abstract
The primary objective of this project was to conduct quantitative investigations on impacts of non-native ‘quagga mussel,’ Dreissena rostriformis bugensis in the UK range. A freshwater bivalve mollusc from the Ponto Caspian region, the quagga mussel was considered, prior to first record, a threatening invasive species to UK biodiversity. Given lack of regional knowledge regarding the influence of D. r. bugensis on native ecology, quantitative research into observable and potential impacts of the species was considered important.Following a general introduction and statement of project aims, this dissertation was divided into three parts. Part 1, titled ‘observable impacts,’ comprised two data chapters; each explored influences of D. r. bugensis on invertebrate communities in situ. The first chapter presented an annual-scale benthic survey to compare invertebrate communities between invaded and uninvaded lotic reaches within the UK range. The second described benthos colonisation experiments testing the influence of mussel shells at higher densities than found at the time.
Part 2 was titled ‘impact mechanisms’ and contained three chapters. The first presented results from laboratory flume experiments to assess geomorphic impacts of D. r. bugensis in rivers. The second chapter provided extended discussion on the impacts of suspension feeding Dreissena spp. in rivers, incorporating a series of ex situ and in situ experiments on D. r. bugensis in the the UK invaded range. The third chapter was derived following first record of invasive shrimp Dikerogammarus haemobaphes within the D. r. bugensis range. Possible commensalism between Dreissena spp. and other Ponto Caspian species was investigated in the context of Invasional Meltdown Hypothesis (Simberloff and Von Holle 1999).
Part 3 of the dissertation, titled ‘likelihood of impacts,’ included two final chapters. The first aimed to assess the preferred habitats of D. r. bugensis within the known invaded range. Additionally, this work analysed change in reach-scale mussel densities since the annual-term survey of part 1. Further, discussing whether other regional environments could be at risk of future invasion. The final dissertation chapter contained a summary of project conclusions with synthesis of all findings to comment on potential impacts of D. r. bugensis in the invasive range and other UK freshwaters.
| Date of Award | 1 Aug 2019 |
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| Original language | English |
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| Supervisor | Michael Chadwick (Supervisor) & Robert Francis (Supervisor) |