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Title: Palynomorph and palynodebris distributions in modern estuarine sediments
Author: Farr, Katherine Mary
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1988
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Intertidal sediments of modern British and Irish estuaries and embayments have been analysed to investigate the degree to which such deposits are characterised by their palynomorph assemblages. Localities selected for study were: the Ythan Estuary, Aberdeenshire; the Montrose Basin, Angus; Chichester Water, Sussex; the Tresillian and Fal estuaries, Cornwall; the Shannon and Clarinbridge estuaries, Ireland; and numerous estuaries feeding into the Solway Firth. At the head of a typical estuary there is a sharp and conspicuous change in the palynomorph assemblages: brackish and marine palynomorphs are abundant throughout the tidally influenced reaches whereas, except for a few specimens probably brought in by birds or other animals, they are absent upstream of the tidal limit. In general, marine and brackish forms show few distinguishable trends in distribution between the head and mouth of the estuary, being evenly spread by tidal flushing. Dinoflagellate cysts, for example, are as abundant in the upper reaches as they are downstream. The marine/estuarine transition is poorly characterised by changes in palynomorph assemblages. Relative proportions of most of the terrestrially-derived palynomorphs increase upstream although woody fragments have a greater relative abundance in the lower reaches, possibly because they are more resistant and can remain in suspension longer than most other types of plant debris. Biogenic pyrite and invertebrate faecal material both occur more commonly in estuarine deposits than in fluvial deposits. The samples contain a mixture of marine and brackish organisms and terrestrial palynomorphs. An eider duck faecal pellet, collected from the Ythan Estuary, contained a diverse palynomorph assemblage similar to that of the intertidal mud samples. Freshwater species are rare in intertidal deposits and comprise mainly turbellarian egg cases. Almost all aquatic palynomorphs present in the samples have been recorded by other workers from marine sediments. Of those which appear to be restricted to environments of reduced salinity, most are eggs or egg cases and one of these is described for the first time (Palynomorph Y). Fluvial and lacustrine samples contain terrestrial palynomorphs, turbellarian cocoons and a small number of unidentified cyst-like structures. An incidental observation showed that, on gentle heating, dinoflagellate cysts that had undergone palynological processing dehisced and released their cell contents. This may be a physical response of the cyst to heat, by expanding and rupturing, or the cysts may be sensing a 'spring' temperature rise and attempting to hatch. The viability of the emergent protoplasm is unknown. The contents of the thesis will help to refine the use of palynomorph assemblages in the reconstruction and predictive modelling of Quarternary and perhaps older depositional environments, in particular, in distinguishing estuarine sediments from fully marine and freshwater sediments.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available