The age structures of several populations have been recorded at ten year intervals for the past 20 years. The changes in the age structures of these populations indicate that small mussels are often under recorded due to sampling bias. Some populations show unchanged age structures indicating that levels of recruitment have been maintained, whereas others show aging population structures, with very few young mussels being recruited to the population. The habitat requirements were modelled using a number of techniques. All the models indicate that, in Scotland, physical habitat parameters are the most important for determining habitat suitability at the between river scale. Models of habitat requirements for juvenile mussels indicate that the sediment variables, particularly the amount of silt present, are most important, while models for adult mussels also include macrohabitat variables. However, the resolution of these models is compromised by the effects of pearl fishing, which has reduced the densities or removed mussels from areas of otherwise suitable habitat, thus resulting in a lack of differentiation between suitable and non suitable sites. The genetic diversity and differentiation within and between populations was examined and showed that Scotland contains some populations with a high genetic diversity when compared to other populations studied in Europe. Some populations, however, were shown to be lacking diversity, and had a small effective population size, making them vulnerable to the effects of inbreeding depression and genetic drift. Differentiation between rivers showed that rivers geographically close were not always the most genetically similar. This may have implications during translocation or restocking programmes. Recommendations are made for future conservation efforts.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:499734 |
| Date | January 2008 |
| Creators | Tarr, Elizabeth Clare |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=25192 |
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