Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.704678
Title: The ecology and taxonomy of marine dinoflagellates in Scottish sea lochs
Author: Lewis, Jane Mary
Awarding Body: University of London
Current Institution: Royal Holloway, University of London
Date of Award: 1985
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Abstract:
The ecology and taxonomy of dinoflagellates was investigated in 1982 and 1983 in sea-lochs and coastal waters of north-western Scotland, in order to provide a better understanding of conditions leading to blooms harmful to mariculture. Because such blooms are rare the ecology of all common thecate dinoflagellates was studied, particular attention being paid to the cyst stage and its role in bloom initiation. Creran, a fjordic sea-loch near Oban, was the main site of study; water column sampling was carried out regularly in 1982 and 1983 and the sediments were sampled for cysts in 1983. Distribution of motile dinoflagellates and their cysts on the west coast of Scotland was also investigated on cruises of the R.V. Calanus in the summers of 1982 and 1983. Identification of cells was carried out by light microscopy supplemented by studies using scanning electron microscopy. Links between cysts and motile stages were made by hatching experiments, and these and scanning electron microscopy have led to the discovery of some new cyst-theca relationships. In Loch Creran the first peak of dinoflagellate numbers occurred in May or June with warming of the water column and was dominated by Scrippsiella spp., accompanied in 1983 by Gonyaulax tamarensis. During July and August there was a mixed population, including Serippsiella spp., Heterocapsa triquetra, Protoperidinium spp. and Diplopsalis spp. Salinity stratification at the end of August preceded an autumn succession of G. polyedra, Prorocentrum micans and Ceratium species. Observations suggest that G. polyedra cysts sink rapidly and are retained within the loch, seeding blooms in subsequent years. Two other life strategies were hypothesized as the causes for different observed patterns of seasonal distribution. One involves non-cyst-forming species (for example Protoperidiniumbipes and Prorocentrum micans) present in the loch as motile cells in small numbers throughout the year, and occasionally reaching high concentrations. The other involves species (for example Protoperidinium depressum and Ceratium furca) whose motile cells are transported to the loch by tidal exchange or estuarine circulation from the sea outside. Seventy-two species of motile thecate dinoflagellates were found in the distributional study. Dinoflagellate abundance and variety were greatest in well- or partially-stratified water columns. Of potentially toxic species only Gonyaulax tamarensis was found to be widespread in 1983. Cysts varied in their distribution, with numbers higher in sea-lochs than in Firths and Sounds. Considerable sub-surface populations of cysts were noted in the sediments and viable cysts were encountered at 5 cm depth.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.704678  DOI: Not available
Keywords: Ecology
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