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Title: Effects of Diatom-Derived Polyunsaturated Aldehydes (PUAs) on the Freshwater Survival of the Atlantic Salmon (Salmo Salar L.)
Author: Dunstan, Hannah Jane
ISNI:       0000 0001 3435 9597
Awarding Body: University of Newcastle-Upon-Tyne
Current Institution: University of Newcastle upon Tyne
Date of Award: 2008
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Owing to changes in agricultural practices and increased intensity offanning, many river catchments in the UK are experiencing increased nutrient loading. This often results in increased incidence ofhannful algal blooms. Although diatoms account for much of the world's primary production, and have been considered the basis ofmany aquatic food webs, they have been implicated in deleterious effects on zooplankton grazers. The River Bush has an established Atlantic salmon (Safmo safar L.) population and associated long tenn data set, that has shown a significant decline in ova to smolt survival, which has in part has been linked to inputs ofnutrients and increased photosynthetic growth. The River Tyne also has an established salmon population and associated long tenn data set and has seen a marked increase in the population with improved water quality. This study considers the differences in basic water chemistry between the two rivers that may account for differences in diatom growth and investigates the inhibitory effects ofdiatom produced compounds. The rationale being that diatom-derived polyunsaturated aldehydes (PUAs) may act on fresh water invertebrates thereby affecting the food source ofAtlantic salmon fry and indirectly impacting their survival, or possibly by causing toxicity to the salmon eggs and alevins. The River Bush was found to have higher nutrient loading than the River Tyne, indicating greater potential for diatom growth, though analysis ofspecies composition showed greater diversity in the River Tyne. Ge/MS analysis ofbenthic diatom samples from both rivers revealed the presence of PUAs. Acute and chronic toxicity assays, on Daphnia magna (as a model organism for the invertebrate prey ofjuvenile salmon) found decreased growth and reproduction, and increased physiological stress. Assays on Safmo safar also showed decreased growth and increased morphological abnonnality. The implications ofthese findings are discussed in relation to the decline of wild salmon populations.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available