Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234370
Title: Protozoa in lowland stream sediments, with particular reference to ciliates of the order Peritrichida
Author: Harmsworth, Gillian Catherine
ISNI:       0000 0001 3532 0790
Awarding Body: University of Southampton
Current Institution: University of Southampton
Date of Award: 1988
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Abstract:
This study of protozoa in gravelly stream sediments was carried out on two Hampshire streams with contrasting physical and chemical characteristics. The abundance and distribution of protozoa, particularly peritrich ciliates, was measured over the period of one year. Population densities of peritrichs ranged between 2 and 35 cm⁻² of stone surface area (approximate mean 8 cm⁻²) in a chalk stream and between 0.5 and 110 cm⁻² in an unbuffered woodland stream. Abundance varied seasonally with both spring and autumn peaks in population, together with large day-to-day fluctuations. There was evidence of spatial and temporal separation of the three main genera encountered (Carchesium, Vorticella and Platycola). The main factors influencing their distribution and abundance were considered to be temperature and bacterial food resources. Temperature affects primary production and hence the nutrients available to bacteria; it also directly affects the growth rates of both bacteria and ciliates. The effects of water flow were also considered. Free-swimming protozoan populations in the interstitial water were also enumerated, and were found to have similar abundance and distribution at both sites. The average ciliate density was 0.4 x 10⁴ 1⁻¹ and average flagellate density was 3.0 x 10⁴ 1⁻¹. In situ rates of colonisation of various surfaces by peritrichs were investigated. Initially, artificial surfaces were colonised more rapidly than surfaces normally present in the experimental area, but population densities tended to stabilise with time (between 30 and 60 days) at similar levels. These differences in the early stages of colonisation were concluded to be due to conditioning of the surfaces by bacteria; the type of surface may influence the quality and quantity of bacteria present, and in turn, influence the peritrich community. A method was devised to study and measure the growth rate of peritrichs by video recording; during testing of this method it was found also to be useful to observe predation. Results indicate that this should be useful in future studies of such phenomena.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.234370  DOI: Not available
Keywords: Protozoan ecology
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