TITLE:
Phytoplankton Dynamics of Mokolo and Mopa Ponds in Bertoua City (East-Cameroon)
AUTHORS:
Janvier Kengne Tenkeu, Gwladys Joelle Mogue Kamdem, Nectaire Lie Nyamsi Tchatcho, Narcisse Mvondo, Isabelle Appoline Kalieu, Wilfried Takam, Serge Hubert Zebaze Togouet
KEYWORDS:
Bertoua, Dynamics, Hypereutrophic, Phytoplankton, Ponds
JOURNAL NAME:
Open Journal of Ecology,
Vol.10 No.7,
July
29,
2020
ABSTRACT: This study aims to improve the understanding of algal community’s
dynamics in response to different environmental factors in two dam ponds
(Mokolo and Mopa) in the city of Bertoua (East-Cameroon). Physicochemical and
biological analyzes were carried out monthly by direct sampling at the surface
and using Van Dorn bottle at 1 m depth. The organisms were collected using
transparent glass vials of about 500 ml and fixed with 2.5 ml of a lugol solution,
then analyzed using the Utermôhl method. Physicochemical analyzes show low
transparency (75 cm) of the
ponds despite their shallow depth (≤150 cm), high levels of
dissolved oxygen (>60%), BOD5 (>30 mg/L) and chlorophyll “a” (>30 μg/L). These data made it
possible to categorize the Mokolo and Mopa ponds as hypereutrophic with
nitrogen as the limiting factor for eutrophication. Biological data show quite
diversified ponds with 138 species identified in
Mokolo Pond and strongly dominated by Diatoms with 2951 ind. representing 46%
of the total abundance. In Mopa Pond, 147 species were identified, mainly
represented by Chlorophyceae with 3629 ind. representing 52% of the total
abundance. Azpeitia africana (Mokolo) and Eresmophaera gigas (Mopa) were the most
represented taxa during the study. This study will have deduced that the
structure and dynamics of algal communities are under the control of different
factors or processes that interact simultaneously, namely ascending factors or
bottom-up corresponding to nutrient resources and sunlight and descending
factors or top-down that are exerted by grazing and active physiological
substances produced by other algae that are known to influence phytoplankton.