Environmental Patterns, Diversity, and Phytoplankton Composition in Urban Lakes of Yamoussoukro, Côte d'Ivoire
Nangoh Kouamé Martin *
Laboratory of Environment, Climate, Health, Engineering and Sustainable Development, Department of Plant Biology, Faculty of Biological Sciences, Peleforo Gon Coulibaly University, BP 1328 Korhogo, Côte d’Ivoire.
Camara Maboundou
Laboratory of Environment, Climate, Health, Engineering and Sustainable Development, Department of Plant Biology, Faculty of Biological Sciences, Peleforo Gon Coulibaly University, BP 1328 Korhogo, Côte d’Ivoire.
Niamien-Ebrottie Julie Estelle
Laboratory of Environment and Aquatic Biology, Department of Environmental Science and Management Nangui Abrogoua University, 02 BP 801 Abidjan 02, Côte d’Ivoire.
Edia Oi Edia
Laboratory of Environment and Aquatic Biology, Department of Environmental Science and Management Nangui Abrogoua University, 02 BP 801 Abidjan 02, Côte d’Ivoire.
Ouattara Allassane
Laboratory of Environment and Aquatic Biology, Department of Environmental Science and Management Nangui Abrogoua University, 02 BP 801 Abidjan 02, Côte d’Ivoire.
*Author to whom correspondence should be addressed.
Abstract
Urban lakes are exposed to environmental pressures that can influence phytoplankton communities and water quality. This study assessed the taxonomic composition, richness, abundance, diversity and relationships with physicochemical variables in eight urban lakes of Yamoussoukro, Côte d’Ivoire. Physicochemical measurements and phytoplankton samples were collected at 28 stations during 12 bimonthly campaigns between December 2015 and October 2017. Taxa were identified by light microscopy, and community patterns were examined using diversity indices, principal component analysis (PCA) and redundancy analysis (RDA). A total of 191 phytoplankton taxa belonging to 61 genera and five major phyla were recorded. Chlorophyta (69 taxa) and Euglenophyta (61 taxa) jointly accounted for 68.06% of taxonomic richness. Lake 5 exhibited the highest richness (103 taxa), whereas Lake 7 had the lowest (11 taxa). Rarefied richness, Shannon diversity and Pielou evenness were generally higher in Lakes 5, 6 and 8 and lower in Lake 7. Jaccard coefficients indicated limited compositional similarity between many lake pairs. Phytoplankton abundance, biomass and chlorophyll-a concentrations varied among lakes. The first two PCA axes accounted for 60.5% of physicochemical variability, while the first two RDA axes accounted for 65% of the reported variance. These analyses associated spatial differences in phytoplankton composition with gradients in nutrients, conductivity and dissolved oxygen. Overall, the findings indicate pronounced spatial heterogeneity among the studied lakes and support comparative phytoplankton assessments as a component of urban-lake monitoring.
Keywords: Phytoplankton, taxonomic diversity, urban lakes, water quality, Yamoussoukro