International Journal of Aquaculture 2013, Vol.3, No.2, 4
-
7
http://ija.sophiapublisher.com
4
Research Report Open Access
The Phytoplankton Species Composition and Abundance of Ogun River,
Abeokuta, Southwestern Nigeria
Benjamin Onozeyi Dimowo
Department of Aquaculture and Fisheries Management, College of Environmental Resources Management, Federal University of Agriculture, Abeokuta, Ogun
state, Nigeria
Corresponding author email:
benjamindimowo@yahoo.com
International Journal of Aquaculture, 2013, Vol.3, No.2 doi: 10.5376/ija.2013.03.0002
Received: 9 Jan., 2013
Accepted: 17 Jan., 2013
Published: 7 Feb., 2013
Copyright: © 2013 Benjamin. This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use,
distribution, and reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article:
Benjamin, 2013, The Phytoplankton Species Composition and Abundance of Ogun River, Abeokuta, Southwestern Nigeria, International Journal of
Aquaculture, Vol.3, No.2 4-7 (doi: 10.5376/ija.2013.03.0002)
Abstract
The phytoplankton species composition and abundance in Ogun River, Ogun state, Southwest Nigeria was studied for a
period of seven months (December, 2011 - June, 2012), a total of forty-one genera belonging to five taxonomic groups were recorded
from Ogun River. The phytoplankton species composition was surpassed by
Chrysophyta
with 15 species consisting of 36.6%
followed by
Chlorophyta
with 14 consisting of 34.1%. This was followed by
Cyanophyta
(7
species) consisting of 17.1%,
Euglenophyta
with 3 species consisting of 7.3% and
Pyrrophyta
with 2 species consisting 4.92%.
Cyanophyta
was the highest in
abundance consisting of 41% while the lowest in abundance was
Pyrrophyta
consisting of 1.5%. The low nature of phytoplankton
abundance and diversity observed in this study must have been caused by the polluted nature of the water due to the anthropogenic
activities carried out around its shores The dominance of
Cyanophyta
in this river is similar to findings from Lake Victoria, Lake
Bishoftu, Lake Chaohu and the temple pond of
Thirupour
.
Keywords
Phytoplankton species; Abundance; Composition; Southwestern Nigeria; Ogun River
Introduction
Phytoplankton (singular-phytoplankter) is very small
(
microscopic) free floating plants that drift with water
currents. They exist in both freshwater and marine
environments (Microsoft Corporation, 2009; Lindsey
and Scott, 2010; Encyclopædia Britannica, 2012).
Like terrestrial plants, they use carbon dioxide, release
oxygen and convert minerals to the form that animals
can use. They are responsible for 50 percent of all
photosynthetic activity on Earth. They can be divided
into two divisions which include: phototrophic
bacteria (which is made up of purple sulphur bacteria
and green sulphur bacteria) and algae (which is made
up of
euglenophyta
,
chrysophyta
,
phaecophyta
,
rhodophyta
,
pyrrophyta
and
cyanophyta
) (
Edmondson,
1958).
Their composition and abundance is highly
dependent on the availability of sunlight, carbon
dioxide and nutrients such as nitrate, phosphate and
silicate etc. These factors influence their density and
distribution
throughout
the
water
column.
Phytoplankton is very important because they form
the base with which the aquatic ecosystem is
culminating (Reynolds, 1984). They are a source of
food to almost all aquatic life either directly or
indirectly. In aquaculture, they serve as a food stock
for zooplankton which are in turn fed to fish larvae
reared in fish hatcheries (Moncheva and Parr, 2010;
Lindsey and Scott, 2010). As beneficial as
phytoplankton are, they could also be harmful. Under
certain conditions such as pollution of water body
with sewage and human excreta, certain harmful
phytoplankton predominate and produce bio toxins
which affect the taste and colour of water, impact bad
taste on fish and harbor diseases thereby causing
massive fish kills. Examples of such harmful
phytoplankton include:
Cyanophyta
(
Cyanobacteria
/
blue green algae) which produces geosmin which is a
toxin that impacts a bad flavor on fish especially
bottom dwellers (such as Cat fish and carp) and
rhodophyta
which causes red tides following massive
fish kills. The beneficial and harmful importance of
phytoplankton cannot be undermined. There is
therefore need to carry out routine checks on the
phytoplankton species composition and abundance of
water bodies worldwide.
River Ogun is a perennial river prone to pollution due to
the human activities carried out around its borders. This
study is therefore aimed at investigating the phytoplankton
abundance and species composition of River Ogun.