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A study of the phytoplankton of Swansea Bay. / Jameel Abdulla Mohammed Abbas

Swansea University Author: Jameel Abdulla Mohammed Abbas

Abstract

The intention at the beginning of this study was to investigate the primary productivity of phytoplankton in Swansea Bay. This productivity was measured fortnightly using the 14C-fixation technique. Biomass standing stock was measured as chlorophyll a m-3 and as cell concentration. Concurrently, sev...

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Published: 1986
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa42317
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Abstract: The intention at the beginning of this study was to investigate the primary productivity of phytoplankton in Swansea Bay. This productivity was measured fortnightly using the 14C-fixation technique. Biomass standing stock was measured as chlorophyll a m-3 and as cell concentration. Concurrently, several environmental factors were measured to relate any possible effect on phytoplankton growth and species succession. The factors studied were seawater temperature, salinity, nitrate, nitrite, ammonia, phosphate, silicate and some meteorological data supplied by a local station. A weak positive correlation was found between net phytoplankton cell number and phytoplankton chlorophyll. Based on this finding, the relative importance of phytoplankton size classes as primary producers was investigated. As a result of this investigation, it has been found that most of the primary productivity (80%) was carried out by phytoplankton less than 20 mum. Special attention was given to the role of nitrate in the 14C-fixation by different phytoplankton size classes and by phytoplankton species grown in synthetic medium. The effect of nitrate on the 14C-fixation by the size classes was investigated using nutrient enrichment technique. From these experiments it has been found that nitrate enrichment stimulates the increase of 14C-fixation by the different size fractions at different rates. When nitrate was given to nitrogen-starved Thalassiosira sp. and Asterionella japonica, it was found that nitrate was taken up at the expense of 14C-fixation. It was also found that algal cells cultured in medium with high nitrate concentration increased their chlorophyll a content. It was concluded from this study that nano and picoplankton play an important role in the productivity of Swansea Bay, and that nitrate plays a significant role as a limiting nutrient not only to the primary productivity of the phytoplankton population as a whole but also to the different phytoplankton size classes.
Keywords: Microbiology.;Biological oceanography.
College: College of Science