Chizea, F.D.

Ekere, E.

Farri, T.A.

Kusemiju, K.

English

Aquatic Commons

WATER HYACINTH INFESTATION OF RIVER NIGER AND
KAINJI LAKE, NIGERIA
K. KUSEMIJTJ*, T.A. FARRI**, F.D. CHIZEA** and E. EKERE***
* Departmeni of Biological Sciences, University of Lagos. Lagos, Nigeria.
* * NASENI, Federal Ministry of Science & Technology, Lagos..
* Marine Police, Forces Headquarters, Lagos.
INTRODUCTION
Water hyacinth, Richhornia crassipes
(Mart) is a serious aquatic pest in many
parts of the world. Its rapid growth has
clogged major waterways and created
problems associated with navigation,
national security, irrigation and drainage,
water supply, hydro-eleetrieity and fishing
in many countries.
The first surge of the weed in Nigeria
was noticed in September, 1984 along the
Badagry Creek in Lagos State where the
weed formed a 'mat' over the water
surface. By Jani.ary 1985, it had spread to
the creeks and lagoons in Lagos and its
environs. The invading weed entered the
Nigerian coastal waters through the Porto-
Novo Creek in the Republic of Benin
(Kusemiju et al, 1988). Fear was
expressed then that the weed might spread
to other water bodies in Nigeria.
By 1986, the weed had crossed the
Lagos Lagoon and has since covered most
of the intricate system of waterways made
up of rivers, lagoons and creeks in Lagos,
Ogun, Ondo, Edo, Delta and beyond. The
99
weed is spreading fast along the coastal
states of Nigeria.
PRELIMINARY INVESTIGATIONS
IN RIVER NIGER
Following the report from the
Executive Governor of Kebbi State on the
occurrence of an aquatic weed suspected
to be water hyacinth which was
constituting a menace in the River Niger,
the Chairman of the National Agency for
Science & Engineering Infrastructure
(NASENI) directed an immediate
investigation of the area. The
investigation team accompanied by an
official of Kebbi State Fisheries
Department toured the State extensively
and met a surge of water hyacinth in the
River Niger at Yauri, Headquarters of
Yauri Local Government Area, Kebbi
State. Since Yauri was quite close to
Kainji Lake, it was noted then that the
weed posed a threat to the lake. It was
also suspected that the water hyacinth in
the River Niger entered Nigeria via the
Niger Republic. It was agreed that the
team should carry out a detailed survey of
the affected areas and the extent of the
infestations.
I?1]LD INVESTIGATIONS
Following the directive of the Chair-
man of NASENI, the team carried out a
detailed survey of water hyacinth
infestation in the River Niger from 20th —
23'' December, 1992. The field trip
covered the entire length of the River
Niger from the Niger Republic border to
Warra end of the Kainji Lake (Fig. 1).
Water hyacinth was seen flowing into
Nigeria through Dolekaina, a village some
15 minutes drive by boat from Lob.
Between Dolekaina and Lob, a large
population of Water hyacinth was seen
entangled by Panicum maximum (grass
family) and Polygonum lanigerum
(Polygonaceae). Strands of water hyacinth
were also seen floating downstream on the
river. Enquiries from the Marine Police
located at Lob indicated that major
infltw of water hyacinth from the Niger
Republic is during July and August and
the surge started in 1989. The concen-
tration was low in November/December
since most of the weeds were already
carried iownstream to Nigeria by the fast
current of the river. The River Niger from
Lob downstream was surveyed estimating
also the level of water hyacinth
infestation.
At Bagudo, a bridge is built across the
River Niger. The Bagudo bridge is located
mid-way between Dolekaina and Yauri
and is about 1 km long. From Bagudo to
Yauri, the same pattern of distribution
was observed with a large proportion of
the weed massed along the shores of the
river.
ECONOMIC AND ECOLOGICAL
IMPLICATIONS
Kainji Lake with a surface area of
about 1250 km2 provides a highly suitable
site for the proliferation of water hyacinth.
According to Khan and Thyagarajan
(1988), under the most favourable
conditions, 10 plants can multiply to
600,000 in only eight months. If
immediate action is not taken, we may
soon expect the whole of the lake to be
covered by the weed. Water hyacinth
cover is detrimental to fish due to lowered
dissolved oxygen, inhibition of phyto-
plankton production and restriction of the
larger fish.
One of the most insidious effects of
water hyacinth infestation is the loss of
great deal of water through evapotrans-
pirafton. According to Baruah and Singh
(1984), water loss by evapotranspiration
from water hyacinth-covered waters has
been reported to be up to 9.84 times
higher than evaporation from open water.
This water loss may reach serious
proportion in areas of water shortage like
the River Niger and the Kainji Lake.
Water hyacinth also reduces the water
storage capacity of reservoirs by
displacing large volumes of water. It is
said that 405 hectares of water hyacinth
displaced 1.22 x 0 m3 of water in Lake
Rio Kenoa in El Salvador (Gopal and
Sharma, 1981). The indication of all the
above is that Nigeria now has a major
problem on hand with regard to
navigation, fishing and the Kainji hydro-
electric dam which generates power to
most parts of Nigeria and other countries
in the ECO WAS sub-Region.
100
101
Fig. 1. The River Nflger from
Lo)o to Kainji Lake
Infested by water
Hyacinth.
Economic losses caused by water
hyacinth infestation is considered to be
quite substantial. Economic losses due to
damage of cultivated crops by water
hyacinth in West Bengal, India amounted
to $24 million in one year (Baruah and
Singh, 1984). According to USAID
(1971), the losses in the United States due
to aquatic weeds including water hyacinth
range up to $110 million annually and this
figure does not include losses due to crop
failure, interference with navigation,
deterioration of wildlife and fish habitat
and effect on public health. From the
foregoing accounts, it is quite obvious that
immediate action must be taken to check
and control the growth on water hyacinth
in the River Niger and Kainji Lake.
CONTROL STRATEGIES
Water hyacinth problem in River
Niger presents a different setting from the
experience in Lagos area. The usual
mechanical harvesting so far employed in
Nigeria cannot be adopted in the Kainji
Lake, neither can one think of immediate
biological or chemical control in the lake
bearing in mind the scattered nature of the
weed. Along the River Niger from
Dolekaina through Lob, Bagudo and
Yauri to Ulaira, mechanical harvesting
will remove the other weeds that presently
help to trap water hyacinth and therefore
open the river course and indeed the
Kainji Lake to heavier infestation. The
long-term solution to the water hyacinth
problem from Dolekaina to Ulaira and in
the Kainji Lake is biological control using
weevils when the short-term measures
suggested below would have been
initiated. The following short and long
term strategies are submitted as control
measures:
Immediate And Short Term Measures
1. Two barriers should be erected at the
border near Dolekaina and near Yauri
to hold back water hyacinth
originating from Niger Republic and
prevent further incursion of the weed
into the Kainj i Lake
Near Dolekaina, the length of the
barrier wiil be approximately 1
km.
Upstream near
approximate length
km.
• Allowance is made for flooding
on both sites on the River Niger.
2. There should be manual clearance of
water hyacinth starting from the Niger
Republic border at Dolekaina up to
tJlaira or to the second barrier at
Yauri. In clearing the water hyacinth,
deliberate effort should be made not
to clear along with it the other local
weeds that presently serve the useful
purpose of entrapping water hyacinth.
3. Immediate step should be taken to
mop up the water hyacinth strands
scattered all over the Kainji Lake. The
edges of the lake should also be
manually cleared of the weed. At least
20 boats must be deplored for this
exercise.
4. Biological control efforts should
immediately be initiated.
Yauri, the
will be 1.5
102
Long Term Solution
Biological control should be initiated
as a long-term solution to the water
hyacinth problem in the River Niger and
Kainji Lake. The weevils (Neochetina
eichhorniae and N. bruchi) and fungal
pathogens can easily be introduced behind
the two barriers at Dolekaina and Yauri
and along the River Niger where water
hyacinth is held in place by the local
weeds; and along the edges of the Kainj i
Lake.
It is suggested that a main Biological
Control laboratory for the weevils be
established at the NIFFR (New Bssa) and
field insectary at Yauri.
Enabling Studies
Enabling studies on the biology of the
weevils including:
Study of the biology of the weevils
Study of the carrying capacity of the
weevils and measurement of the
impact of weevil damage on Water
hyacinth.
o Host specificity to include laboratory
studies on host specificity and field
evidence of specificity.
The basic studies will help in deciding the
various ways to establish the weevil in the
field and monitor what it does to the target
pest. The implementation of planned
biological control programme in Nigeria
for water hyacinth has been stalled in the
past by lack of funds.
Proposal for Use of Grass Carp and
other Aquatic Animals
Water hyacinth is both a menace and
resource. It constitutes a free crop of great
potential value — a highly productive crop
that requires no tillage, fertiliser or
cultivation and has potential for
exploitation as fish feed. The pilot project
now proposed explores the biological
control of water hyacinth by use of
identified fish species namely, the grass
carp, Ctenopharyngodon idella and other
aquatic animals. The grass carp has been
shown to be a very effective method of
water hyacinth control in several countries
including Indonesia, Philippines and
Guyana. The grass carp is a fast growing
fish that feeds voraciously on many
aquatic plants. In the process, the weed is
cleared and one gets sizeable fish thereby
contributing to fish production and
improving the economy of the riverine
people who now regard water hyacinth as
a menace. According to Soerjani (1984) in
Indonesia, in water hyacinth mono-
culture, fish of 6 — 8 cm with a density of
4 — 16,000 fish/ha reduced water hyacinth
population of about 1200 tons/ha with 48
— 83% compared to the potential growth
in two weeks.
CONCLUSION
This survey confirmed that the source
of water hyacinth in the River Niger and
Kainji Lake is from the Niger Republic.
The infestation of Kainji Lake poses a
major problem to the Kainji Dam and
indeed the hydro-electricity supply of
Nigeria and other countries in the West
African Sub-Region. This is a new
dimension to the water hyacinth problem
in Nigeria and it must immediately be
tackled. Bilateral initiatives with Niger
Republic should also be immediately set
in place.
ACKNOWLEDGEMENTS
The co-operation of Kebbi State officials
including the Commissioner for Agri-
culture and Natural Resources and his
Director-General is gratefully ackriow-
ledged. Thanks are also due to Aihaji
Ibrahim Kangiwa, Director of Jrrigation
Engineering and Aihaji Muazu Gulma,
Chief Fisheries Officer, Kebbi State who
accompanied us to the field. The financial
support provided by NASENI of the
Federal Ministry of Science and Tech-
nology is gratefully acknowledged.
REFERENCES
Baruah, J.N. and H.D. Singh (1984). An
environmentally sound scheme for the
management of Water hyacinth through its
utilisation. Proceedings of International
Conference on Water Hyacinth, Hydrabad,
India, February 7—11, 1983,
Gopal, B. and K.P. Sharma (1981). Water hyacinth.
Hindasia, New Delhi.
Khan, M.N.G.A. and G. Thyagarajan (1988). Water
hyacinth: Historical background and CSC
initiative. Proceedings of International
Workshop on Water Hyacinth. Federal
Ministry of Science and Technology
Publication, Lagos. 19 —25.
Kusemiju, K., O.T. Okusanya, TJ.V. Akpata and
JA. Oyenekan (1988). The surge of water
hyacinth in the Lagos Lagoon. Proceedings of
the International Workshop on Water
Hyacinth, Federal Ministry of Science and
Technology, Lagos. 76— 79.
Ita, E,O. (1994). Aquatic plants and wetland
wildlife resources of Nigeria. GIFA Occasional
Paper No.21. Rome, FAO. 52 pp.
Soerjani, M. (1984). Indonesia experience in water
hyacinth utilisation. Proc. of Intern. Gonf on
Water hyacinth, Hydrabad, India, Feb. 7— 11,
1983.
USAID (1971). Economic damage caused by
aquatic weeds (Preliminary Survey). US Office
of Science and Technology, Agency for
Industrial Development, Washington. 13 pp.
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Water hyacinth infestation of River Niger and Kainji Lake, Nigeria

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Water hyacinth infestation of River Niger and Kainji Lake, Nigeria

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