The Annual Cycle of Nutrients and Phytoplankton Dynamics in a Shallow Monomictic Lake in Scotland (Loch Rusky)

Romo Perez, Susana Gabriela (1987) The Annual Cycle of Nutrients and Phytoplankton Dynamics in a Shallow Monomictic Lake in Scotland (Loch Rusky). MSc(R) thesis, University of Glasgow.

Abstract

Loch Rusky showed monomictic characteristics, with thermal stratification occurring through the summer. Dissolved oxygen was depleted in the hypolimnion in the late summer but remained near saturation levels through the seasons of water mixing. Changes in the nutrient concentrations in the water (such as nitrate, phosphate and silicate) were related to phytoplankton community changes (e. g. Diatom spring increase), external supply (e.g. nitrate, sulphate, chloride, COD) and dissolved oxygen levels (e.g. phosphate). The seasonal phytoplankton community started to increase its biomass in April, reaching a single summer peak in July and later a small autumnal peak before falling to lower population numbers after November. The spring community was dominatted by diatoms such as Asterionella formosa and Melosira italica , the summer by Cryptomanadales such as cryptomonas ovata and Rhodomonas minuta var nanoplanctica which attained a very rapid maximum in biomass in mid-summer and by colonial Cyanobacteria in the autumn. The primary production was correlated with the phytoplankton standing crop only in early spring, showing small peaks in mid-summer and winter months. An analysis of variance in the method on the routine Carbon-14 method showed fairly low variance for the whole method although, cell rupture during filtration particularly affecting nanoplankton, could mask the production results in summer. The diversity calculated by the Shannon-Weaver index was strongly influenced by the relative abundance of few species. The maximum phytoplankton diversity was registered in winter. The seasonal succession pattern of the zooplankton population was dominated by Rotifera such as Keratella cochlearis and Polyarthra remata and the copepod Diaptomus qracilis which occurred mainly in the epilimnion during summer. Cladocera was insignif icantly represented in the zooplankton. Some degree of trophic relationship was observed between nannoflagellates and rotifers seasonal populations.

• Item Type: Thesis (MSc(R))
• Qualification Level: Masters
• Keywords: Limnology, Biogeochemistry, Microbiology
• Date of Award: 1987
• Depositing User: Enlighten Team
• Unique ID: glathesis:1987-77541
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 14 Jan 2020 09:05
• Last Modified: 14 Jan 2020 09:05
• URI: https://theses.gla.ac.uk/id/eprint/77541