International Journal of Aquaculture 2013, Vol.3, No.3, 8
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10
http://ija.sophiapublisher.com
10
2004;
Oketola et al., 2006). A 100 square km area
around River Ogun has an approximate population of
3 637 013 (0.03637
persons per square meter) and an
average elevation of 336 meters above the sea (Travel
Journals, 2012). Numerous human activities such as
bathing, washing of clothes, locust bean processing
and transportation were noticed. Indiscriminate
dumping of human excreta was observed at two of the
sampling stations and this may constitute sources of
pollution to the river. Four sampling stations were
established and include:
3.1.1
Station 1 (Ibẹrẹkodo)
It is located just downwards the Ogun State Water
Works Corporation at Arakanga. The water is cured by
the corporation and dispensed through underground
pipes to respective homes. The river here is
characterized by a dam/spillway and high concrete
dykes. The water is generally very clear and has good
aesthetic quality. The activities here are majorly
fishing, bathing, dam maintenance and fishing gear
mending. No farmland was observed at this station.
3.1.2
Station 2 (Agọ ika)
It is located close to the FADAMA III supported ferry
for transportation to Lafenwa. The vegetation around
the banks is very dense. The activities here includes:
locust bean processing, bathing, washing of clothes
and transportation by ferry. The river here is also used
for refuse and human excreta disposal. The activities
of the ferry men could lead to heavy siltation of the
water body causing high turbidity conditions.
3.1.3
Station 3 (Ẹnu gada)
It is located some few steps after the bridge
connecting to Lafenwa. It is characterized by less
dense vegetation and slow flowing water. Activities
carried out here includes: washing of clothes, farming,
indiscriminate dumping of refuse and human excreta.
3.1.4
Station 4 (Off Pepsi bus stop)
It is characterized by rocky outcrops with fast flowing
water. The vegetation consists of terrestrial vegetation
which is less dense. The water is clear and has good
aesthetic quality. Activities carried out here includes:
bathing, washing of clothes and drying of fishing gear
on the rocks.
3.2
Sample collection
Zooplankton samples were collected by the hand
trawling technique. This involves trawling of plankton
at the littoral zone (i.e. at the shore) with 55 µm mesh
size plankton net horizontally. The zooplankton
samples were put into properly labeled plastic
containers and preserved in 4% formalin solution.
This was then taken to the laboratory for analysis. In
the laboratory, a drop was placed onto the glass slide
of the binocular microscope and was covered with a
cover slip for identification and enumeration.
Zooplankton was identified at magnifications of 10×,
40
× and 100× using suitable keys. Enumeration of
zooplankton was carried out following the drop count
method adapted from Verlacar and Desai (2004) was
reported as units or organisms per drop.
Acknowledgement
We thank all the members of staff especially Dr. W. O. Alegbeleye of the
Department of Aquaculture and Fisheries Management, Federal University
of Agriculture, Abeokuta, Ogun state, Nigeria for their collaborative spirit.
We thank Mrs. Binyotubor of the National Institute of Freshwater Fisheries
Research for her support. We also appreciate Mr. T. O. Dimowo for the
statistical analysis.
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