期刊名称：International Research Journal of Environmental Sciences
电子版ISSN：2319-1414
出版年度：2017
卷号：6
期号：2
页码：19-29
语种：English
出版社：International Science Community Association
摘要：Phytoplankton abundance, composition and environmental parameters are monitored in a tropical lake for one year period. Samples of water and phytoplankton in a freshwater of Lake Nokoué located in South of Benin (Lat: 6 °25 N and Long: 2°36 E) were collected every season between November 2015 and October 2016. Data were submitted to Principal Component Analysis (PCA) and to the correlation to determine the grouping pattern of phytoplankton and their relationship to environmental factors. A total of 40 species of phytoplankton belonging to six classes (diatoms, Chlorophyta, Zygophyta, Euglenophyta, Cyanophyta and Xanthophyta) were identified. The diatoms with the specie Cyclotella Meneghiniana and melosiravarians having the highest dominance throughout the period of the study and the Cyanophyta, Euglenophyta with respectively 83.69% and 1.79% and 13.76% in dry season (November and February) against 80.77% for diatoms, 6.17% (Cyanophyta) and 12.75% (Euglenophyta) in rainy season (June and October). The Euglenophyta were significantly presents in dry season (November and February) and made up 13.76% with the species Euglena oxyuris and Euglena acus. The Cyanophyta were represented by the toxic species Microcystis Elachista and Anabaena affinis. The others groups (Chlorophyta and Xanthophyta) were also present but in low numbers. These results show that the seasons influence the distribution of the phytoplankton in the lake. The average chlorophyll a concentration for the seven sites area was 0.103µg/L. The maximum (0.309 µg/L) and the minimum (0.002 µg/L) values were both obtained in rainy season (October 2016). The results of the Principal Component Analysis (PCA) indicated that TP, NH4+, NO3-, NO2-, DO and NTK were mainly the environmental factors that had the greatest influence on the distribution of the phytoplankton community throughout the entire year. It is strongly important that a water quality model is developed for sustainable management of Lake Nokoué.
