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The growth of freshwater phytoplankton at low salinities : with particular reference to estuarine ecology

The growth of freshwater phytoplankton at low salinities : with particular reference to estuarine ecology
The growth of freshwater phytoplankton at low salinities : with particular reference to estuarine ecology

An investigation was made into the fate of freshwater algae in the Tamar estuary to examine the hypothesis that the oxygen minimum, observed at the freshwater-brackishwater interface, was caused by mass mortality of freshwater algae and subsequent oxidative degradation of the lysed cells by bacteria. Axenic unialgal cultures of freshwater phytoplankton were isolated from the River Tamar and the effects of salinity on the algae studied by monitoring changes in chlorophyll, 11211 numbers, particulate organic carbon, rate of uptake of CO. and exudation of labelled photosynthate. Growth rates of both Scenedesmus guadricauda and Nannochloris sp. were not affected by salinities up to 9M,o but growth of both species was reduced at a salinity of S~bo. The rate of exudation in these species atallsalinities was less than 10;: of the rate of total fixation measured. Growth of a mixed community of freshwater phytoplankton was followed in a range of salinities from 0-S0o . The growth rate of the phytoplankton was unaffected by salinities of 0-6%c but was noticeably reduced in salinities of 8%, and above. Very few freshwater algae failed to grow at a salinity of 20~ and all the most abundant species in the river grew in the salinity range 0-600. One species, Cyclotella atomus, grew better between salinities of 2 and hoc than in freshwater. This species formed very large populations (up to 8 mg carbon(-1) at these salinities in the estuary in summer.The size of the upper estuarine community of freshwater algae was dependent on the rate of input of freshwater into the estuary. Large numbers of freshwater algae, dominated by C.atomus, were observed between 0 and Soo salinity, after long periods of low freshwater input. Death of these algae only occurred at salinities greater than S'co, where no oxygen minimum was observed.

University of Southampton
Jackson, Roselyn Heather
Jackson, Roselyn Heather

Jackson, Roselyn Heather (1984) The growth of freshwater phytoplankton at low salinities : with particular reference to estuarine ecology. University of Southampton, Doctoral Thesis.

Record type: Thesis (Doctoral)

Abstract

An investigation was made into the fate of freshwater algae in the Tamar estuary to examine the hypothesis that the oxygen minimum, observed at the freshwater-brackishwater interface, was caused by mass mortality of freshwater algae and subsequent oxidative degradation of the lysed cells by bacteria. Axenic unialgal cultures of freshwater phytoplankton were isolated from the River Tamar and the effects of salinity on the algae studied by monitoring changes in chlorophyll, 11211 numbers, particulate organic carbon, rate of uptake of CO. and exudation of labelled photosynthate. Growth rates of both Scenedesmus guadricauda and Nannochloris sp. were not affected by salinities up to 9M,o but growth of both species was reduced at a salinity of S~bo. The rate of exudation in these species atallsalinities was less than 10;: of the rate of total fixation measured. Growth of a mixed community of freshwater phytoplankton was followed in a range of salinities from 0-S0o . The growth rate of the phytoplankton was unaffected by salinities of 0-6%c but was noticeably reduced in salinities of 8%, and above. Very few freshwater algae failed to grow at a salinity of 20~ and all the most abundant species in the river grew in the salinity range 0-600. One species, Cyclotella atomus, grew better between salinities of 2 and hoc than in freshwater. This species formed very large populations (up to 8 mg carbon(-1) at these salinities in the estuary in summer.The size of the upper estuarine community of freshwater algae was dependent on the rate of input of freshwater into the estuary. Large numbers of freshwater algae, dominated by C.atomus, were observed between 0 and Soo salinity, after long periods of low freshwater input. Death of these algae only occurred at salinities greater than S'co, where no oxygen minimum was observed.

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Published date: 1984

Identifiers

Local EPrints ID: 460375
URI: http://eprints.soton.ac.uk/id/eprint/460375
PURE UUID: cb4f6e9a-3680-4cfa-80b3-28b52d151e86

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Date deposited: 04 Jul 2022 18:20
Last modified: 04 Jul 2022 18:20

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Author: Roselyn Heather Jackson

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