Areal Light Utilization Efficiency of a Natural Community of Pelagic Phytoplankton in a Tropical Lake (Lake Bosomtwe, Ghana)

Francis Emmanuel  Awortwi; Emmanuel  Frempong; Samuel  Aikins; Robert E.  Hecky

doi:10.4314/just.v40i3.1390

Dr. Francis Emmanuel Awortwi the Department of Theoretical and Applied Biology in the Kwame Nkrumah University of Science and Technology, https://orcid.org/0000-0002-5104-0577
Dr. Emmanuel Frempong Theoretical and Applied Biology in the Kwame Nkrumah University of Science and Technology
Dr. Samuel Aikins Department of Theoretical and Applied Biology in the University of Science and Technology https://orcid.org/0000-0001-5016-4140
Dr. Robert E. Hecky Technology (KNUST), Kumasi, Ghana. 2 Large Lakes Observatory, University of Minnesota Dulluth, 2205 E. 5th Street, Dulluth, MN 55812. USA. https://orcid.org/0000-0001-5045-7015

DOI: https://doi.org/10.4314/just.v40i3.1390

Keywords: Phytoplankton, light utilization efficiency, tropical lake, mixed layer depth, Lake Bosomtwe

Abstract

The areal light utilization efficiency, one of the key factors in primary production, of a natural community of pelagic phytoplankton of Lake Bosomtwe (Ghana, West Africa), its seasonal signature and factors that influence it were investigated fortnightly from September 2005 to August 2006 by estimating the percentage of solar radiation utilized by phytoplankton of the lake in primary production. The results indicate an annual mean value of 0.28 ± 0.14% (n=25,CV=51.4 %) which lies at the lower end of values typical for lakes and reservoirs of the world. Mean light intensity within the mixed layer 166.03 ± 77.30 μE m-2s-1 (n=25, CV=51.4 %) did not reach a level that can potentially cause photoinhibition among the dominant phytoplankton groups viz, Cyanobacteria, Dinophyceae, and Chlorophyceae. Both the mean areal light utilization efficiency and mean irradiance in the mixed layer differed significantly between seasons at p < 0.05. Of the physicochemical factors investigated, changes in the mixed layer depth (r2= 29.3%, n=25), surface irradiance (r2= 36.5 %, n=25), mean irradiance in the mixed layer (r2= 23.3 %, n=25), surface water temperature (r2= 17.7%, n=23) and mean temperature in the mixed layer (r2= 22.8 %, n=23) significantly affected changes in the areal light utilization efficiency of the phytoplankton community at p< 0.05. However, of the biological factors measured, changes in the areal light utilization efficiency of the phytoplankton community had a significant predictive value only for the gross primary productivity (r2 = 41.6%, n=25) at p< 0.05.

Author Biographies

Dr. Francis Emmanuel Awortwi, the Department of Theoretical and Applied Biology in the Kwame Nkrumah University of Science and Technology,

Francis is a Lecturer in the Department of Theoretical and Applied Biology in the Kwame Nkrumah University of Science and Technology, Ghana. He has published research articles on the vegetative and production ecology of phytoplankton in lakes in areas such as mixing and stratification effects on phytoplankton community composition, abundance, and productivity in a tropical lake, nutrient effects, and the effects of other physicochemical parameters on the phytoplankton ecology. He has over 34 citations and 234 reads.

Dr. Emmanuel Frempong, Theoretical and Applied Biology in the Kwame Nkrumah University of Science and Technology

Emmanuel Frempong was an Associate Professor in the Department of Theoretical and Applied Biology in the Kwame Nkrumah University of Science and Technology, Ghana. He has several publications and his research focused on environmental health of dams, environmental assessment and evaluation of lotic systems quality, temperate and tropical lake ecology, etc.

Dr. Samuel Aikins , Department of Theoretical and Applied Biology in the University of Science and Technology

Samuel Aikins was a Senior Lecturer at the Department of Theoretical and Applied Biology in the University of Science and Technology, Ghana. He has over 9 research works which focuses on macroinvertebrates in lotic systems, fisheries and aquaculture, plankton ecology in lakes, stream pollution, etc. He has over 19 citations and 547 reads.

Dr. Robert E. Hecky, Technology (KNUST), Kumasi, Ghana. 2 Large Lakes Observatory, University of Minnesota Dulluth, 2205 E. 5th Street, Dulluth, MN 55812. USA.

Robert E. Hecky is an Emeritus Professor of Biology and the Large Lakes Observatory in the University of Minnesota Dulluth. He has over 144 research works in all aspects of lake ecology such as Nutrient and carbon cycling in aquatic systems; limnology and paleolimnology of the African Great Lakes; phytoplankton-nutrient interactions; nutrient biogeochemistry; stable isotope applications to ecology; Hg and organochlorine contamination of food webs. He has over 9235 citations and 31184 reads. He has been a fellow of the Royal Society of Canada Academy of Science since 2008.