Seasonal variations in phytoplankton diversity in the Bui dam area of the Black Volta in Ghana during the pre- and post-impoundment periods

Alhassan, Elliot Haruna

dc.creator	Alhassan, Elliot Haruna
dc.date	2015-03-01
dc.date.accessioned	2016-05-03T15:30:01Z
dc.date.available	2016-05-03T15:30:01Z
dc.identifier	http://revistas.ucr.ac.cr/index.php/rbt/article/view/14230
dc.identifier	10.15517/rbt.v63i1.14230
dc.identifier.uri	https://hdl.handle.net/10669/26790
dc.description	Phytoplankton constitutes the primary producers of aquatic ecosystems and represents the food chain base that supports the commercial fisheries of most water bodies. Nowadays, there is lack of information on phytoplankton assemblages of most reservoirs in Africa. To contribute with this knowledge, this study was carried out to determine the density and diversity of seasonal variations of phytoplankton species in the Bui dam area of the Black Volta, during the pre- (2011) and post-impoundment (2012) periods. For this, a three-level stratified random sampling approach was adopted for 22 months. Phytoplankton samples were obtained by towing a 0.5m diameter phytoplankton net (35μm mesh size and 0.25m2 mouth surface area) from a non-motorized canoe through a distance of about 100m against the current from downstream to upstream of the river. In 2011, 35 species of phytoplankton belonging to four classes, Bacillariophyceae (7.6%), Chlorophyceae (43%), Cyanophyceae (48.6%) and Euglenophyceae (0.8%) were identified. In the 2012 sampling, 18 species belonging to three classes, Bacillariophyceae (2.2%), Chlorophyceae (26.1%) and Cyanophyceae (71.7%) were observed. A total of 17 species of phytoplankton, including Gyrosigma sp., Surirella sp., Carteria sp., Chlosterium sp., Chlorogonium sp., Coelastrum sp., Cosmarium sp., Volvox sp., Chroococcus sp., Coelosphaerium sp., Rivularia sp. and Spirulina sp., were absent during the late post-impoundment period. Mean monthly total phytoplankton abundance decreased from June (7 384 cells/m3) to August (106cells/m3) in 2011. In 2012 however, mean total phytoplankton decreased from February (1 237cells/m3) to August (4cells/m3). The results also showed that variations occurred between seasons among some phytoplankton groups. The dry and pre-wet seasons had significantly (p<0.05) higher mean phytoplankton abundance than the wet season during the 22 months of sampling period. The biotic indices of Shannon-Wiener (H1) were homogenously distributed in the four hydrological seasons of the two years. The phytoplankton groups, Bacillariophyceae, Chlorophyceae, Euglenophyceae and total phytoplankton differed significantly (p<0.05) between the pre- and post-impoundment periods. The total phytoplankton was also significantly (p<0.05) higher in the upstream station than the downstream station indicating the impact of the impoundment on the downstream ecology. Hence, river management strategies should be implemented by hydro-biologist to lessen the impact of the dam on the downstream ecology.	es-ES
dc.format	application/pdf
dc.format	text/html
dc.language	eng
dc.publisher	Universidad de Costa Rica	en-US
dc.relation	http://revistas.ucr.ac.cr/index.php/rbt/article/view/14230/17551
dc.rights	Copyright (c) 2014 International Journal of Tropical Biology and Conservation	en-US
dc.source	Revista de Biología Tropical/International Journal of Tropical Biology and Conservation; Vol 63, No 1 (2015); 13-22	en-US
dc.source	Revista de Biología Tropical/International Journal of Tropical Biology and Conservation; Vol 63, No 1 (2015); 13-22	es-ES
dc.source	Revista Biología Tropical; Vol 63, No 1 (2015); 13-22	pt-PT
dc.source	2215-2075
dc.source	0034-7744
dc.source	10.15517/rbt.v63i1
dc.subject	impoundment	es-ES
dc.subject	chlorophyceae	es-ES
dc.subject	cyanophyceae	es-ES
dc.subject	seasonal density	es-ES
dc.subject	downstream station	es-ES
dc.title	Seasonal variations in phytoplankton diversity in the Bui dam area of the Black Volta in Ghana during the pre- and post-impoundment periods	es-ES
dc.type	artículo original

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