Kusemiju, K.

English

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WATER HYACINTH IN TILE 21ST CENTURY:
A KEYNOTE ADDRESS
K. KUSEMIJU
Department ofMarine Biology and Fisheries,
University of Lagos, Lagos, Nigeria.
INTRODUCTION
Water hyacinth, Eichhornia
crass:es is a serious aquatic pest in
many parts of the world. The menace of
the weed has reached alarming
proportions in many countries. Its rapid
growth has clogged major waterways
and created problems associated with
navigation, national security, irrigation
and drainage, water supply, hydro-
electricity and fishing in many
countries. Its home base is the Amazon
Basin in South America. Water
hyacinth regarded as the most
troublesome weed of the world has
since been willingly or unintentionally
aided by man in its dispersal and present
distribution (Gopal and Sharma, 1981;
Jayanth, 1987).
The first surge of the weed in
Nigeria was noticed in September 1984
along the Badagry Creek in Lagos State
where it formed a 'mat' over the water
surface. By January 1985, it has spread
to the creeks and lagoons in Lagos and
its environs. Investigations by the
University of Lagos team of scientists
revealed that the surge of the weed
entered Nigerian water via the Porto
Novo Creek (Benin Republic) which is
connected to and floWs into the Badagry
Creek. Our prediction then was that if
the immediate and adequate steps were
not taken to check the weed, the Lagos
Lagoon system would become the
avenue for spreading the weed into
other parts of the Nigerian waterways
including Epe, Lekki and Mahin
Lagoons (Kuserniju ci al, 1985). By
1986, the weed had crossed the Lagos
lagoon and has since covered most of
the intricate system of waterways made
up of lagoons and creeks along the coast
of south-western and south-eastern parts
of Nigeria.
Water hyacinth rapidly became a
major problem in the ECOWAS region.
The problem was most pressing in
Nigeria, Benin, Ghana and Cote
d 'Jvoi re. However, the interdependence
of the water network especially the
River Niger system facilitated the
spread of the weed to other countries in
the region.
Water hyacinth infestations have now
covered Senegal, Guinea, Burkina Faso,
Mali and Niger. In 1988, the Nigerian
Federal Ministry of Science and
Technology organised an international
workshop in Lagos on "Water hyacinth,
Menace and Resource".
By 1992, the occurrence of water
hyacinth iii the River Niger and the Kainji
Lake was confirmed. The weed entered
Nigeria via the Niger Republic at Lob, a
border village on the River Niger
(Kusemiju and Chizea, 1992). The
presence of water hyacinth in Kainji Lake
posed a major threat to the Kainji dam
which supplied hydro-electricity to
Nigeria and the Niger Republic. The
economic cost to Nigeria if water hyacinth
in the Kainji Lake was not immediately
brought under control would be
incalculable in terms of hydro-electricity,
fishery and communication.
Recognizing the need for an
integrated approach, ECO WAS (the
Economic Community of West African
States) with financial support from the
African Development Bank (ADB)
engaged EUROCONSULT, a consul-
tancy firm from the Netherlands to
conduct a study on "Control of floating
weeds in the ECO WAS member
countries". The study dealt with the
investigation of degree of infestation of
floating weeds in the member countries,
and the preparation of projects for their
control. Details of the investigations and
identified projects are contained in the
ECOWAS Reports (1995) and will be
very relevant to the control of "Water
Hyacinth in the 21 Century" especially in
the ECO WAS region.
PROBLEMS POSED BY WATER
HYACINTH
Problems posed by Water hyacinth
have been extensively reviewed by Gopal
and Sharma (1981) and Jayanth (1987).
They are summarized as follows:
(a) It impedes the flow of water in
irrigation systems. 40-95% reduction
has been reported.
(b) Prevents the free movement of boats
and other navigation vessels.
(c) It interferes with hydroelectric power
generation. That in very clear
language means that with infestation
of Kainji Lake by water hyacinth,
hydro-electric power from the Kainji
Dam is now threatened.
(d) It reduces the volume of available
freshwater by increasing losses
through evapotraspiration. Various
authors recorded 1.26 to 9.48%
16
increase in water loss, compared to The States of Florida, Louisiana and
open water surface.
(e) It impairs the quality of water. The
plant cover imparts obnoxious smell,
colour and suspended particulate
matter to water, making it unfit for
human consumption.
(fl Dense growth of water hyacinth
causes serious disruptions to other
aquatic life like pliytop.lankton and
fish. According to Gopal and Sharma
(1981), in West Bengal about 45
million kg of fish were annually lost
due to water hyacinth in early i950s.
(g) It provides suitable habitat or food or
both for niolluscan and insect vectors
of diseases like schistosomiasis and
malaria. It gives shelter to adults and
also prevents mosquito larvae and
adults from being preyed upon by
their natural predators like insects,
frogs, fishes etc.
(Ii) The rate of organic production by
water hyacinth is so high that it leads
to silting and gradual drying up of
water bodies.
ECONOMIC IMPACTS OF WATER
HYACINTH
The negative economic impacts of
water hyacinth infestations have long been
appreciated. In the United States, the
problem was so serious that the American
Congress in 1897 made an appropriation
to study the problems posed by the weeds.
17
Texas now spend $1 I million yearly
trying to control water hyacinth in
infested waterways. In the Sudan, the
control of water hyacinth is estimated at
$10 million annually.
The ECOWAS Report (1995)
examined the socio-econornic impacts of
floating weeds in the ECOWAS region.
In the fisheries sector, the potential losses
as a result of water hyacinth infestation in
the sub-region was put at $20 mihiion.
Estimate of other experts indicated that at
current infestation, the losses could even
be of the order of $68 million for the
affected countries. Their calculation was
based on 20% infestation and 40% fish
catch reduction in infested waters.
Irrigated agriculture is of crucial
importance in the ECO WAS region.
Aquatic weed infestation causes marked
losses in agricultural pioduction. The
order of magnitude of the losses in the
region vhen the production of irrigated
agriculture would drop by 1% was
estimated at $36.8 million.
The estimated losses in hydro-energy
production in the sub-region' was put at
between 7 and 14 million US dollars. It
noted that the losses could be substantially
higher. In several countries in the sub-
region, energy production is regularly
interrupted for a number of days, as the
inflow to the turbines had to be cleared of
weeds. Water hyacinth also reduces the
volume of water in the reservoirs through (a) Mechanical Controlillarvesting
evapotranspiration. A summary of losses
caused by floating weeds is given in Table
1. Using a defensive expenditure
approach, the World Bank report,
"Towards the Development of an
Environmental Action Plan for Nigeria"
estimated that water hyacinth control in
Nigeria would cost $50 million annually
and that the species negatively affects
about five million people (Western
African Department, 1990; West Central
Africa Department, 1995).
METHODS OF WATER HYACINTH
CONTROL
In most countries with water hyacinth
problems, three methods have usually
been employed for its control - manual
and mechanical harvesting, biological and
chemical control. The system adopted
however, depends on several
considerations. Even within the same
country, different methods must be
considered based on specific locations and
workability. lii our case, here in Nigeria,
experience on the water hyacinth problem
in past fifteen years confirms the need--for
a mixture of strategies in tackling the
problems in the wide variety of water
bodies that are already infested. In doing
so, the cost effectiveness and
environmental impact of whatever control
strategy is employed must be borne in
mind.
Harvesting is a useful method for
water hyacinth control but there are
serious bottlenecks. To be effective,
the harvesting method has to be fast
enough to outpace the reproductive
potentials 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. To be
effective therefore, the harvesting rate
must be equal to or more than the
growth rate.
So far, mechanical harvesting has
not been a cpntinuous• exercise in
Nigeria. Most of it has been done to
combat a surge or to open u already
blocked waterways. There is bound to
be a recurrence except harvesting is
backed up with regular mopping.
Utilisation of harvested plants is also
suggested to solve the problem of
disposal and also to meet at least
partially the cost of harvesting.
(b) Biological Control
It is believed that on the long-term basis,
biological control will •be relatively
cheaper than other methods of control. By
far, the most successful
18
Table I Summary of losses caused by floating weeds in ECOWAS Region
Source: ECO WAS Report (1995)
agents are the weevils, Neochetina
eichhorniae.
In 1992, rearing of the weevils
started at the Nigerian Institute for
Horticulture (NIHORT) under the
auspices of the National Committee on
Water Hyacinth. Releases were made in
1994 at Iwopin (Lekki Lagoon).
Releases are also in progress at various
sites along the River Niger by NIFFR
(NatiOnal Institute for Freshwater
Fisheries Research) under the
Nigerian/German Kainji Lake Fisheries
Promotion Project. Work on biological
control in Nigeria has been seriously
hampered by funding.
Other biological control methods
involve using herbivorous animals —
grass carp, other herbivorous fish,
manatees, and other herbivorous
animals. For the past few years, this
author has advocated the use of the
grass carp (even as a pilot project). But
no fund has been made available for the
project.
The grass carp has been shown to be
a very effective method of water
hyacinth control in several countries
including Indonesia, Philippines,
Guyana (Soerjani, 1984; Buruah, 1984).
In the process the weed is cleared ünd
one gets sizeable fish thereby
contributing to fish production and
improving the econmy of the riverine
people who now regard Water hyacinth
as a menace. According to Soerjani
(1984), in Indonesia, in a Water
hyacinth monoculture, fish of 6
— 8 cm
with a deiisity of 4 16,000/ha reduced
water hyacinth population of about
1,200 ton/ha with 48 — 83% compared
to the potential growth in two weeks.
(c) Chemical Control
Though chemical control of water
hyacinth is possible, the main objeótions
to its large-scale use in the Nigerian
situation are:
i). the rural population use the creeks,
rivers and lagoons for domestic and
drinking purposes in view of lack of
Sector Low Estimated Losses High Estimated Losses
(millions US$) (millions US$)
28 56
4 8
7 14
36 72
Fisheries
Fleath
Hydro-energy
Agriculture
Total 75 150
19
pipe-borne water. Indeed over 80%
of people of Ilaje area depend on
this as their main source of water
for life. The nearly 30 fishing
villages on the periphery of Lekki
Lagoon (a major area of water
hyacinth infestation) drink the water
directly.
ii). the lagoons and rivers are major
sources of fishing and nursery
grounds for early development of
many species of fishes and shrimps.
Such aquatic animals and sessile
moluscs will be contaminated.
iii). chemical spraying will result in
serious pollution problems as the
water weeds decay.
iv) the unforeseen toxic effects of
residual chemical on aquatic
organisms and man.
Indeed, according to Obeid (1984), after
chemical spraying of water hyacinth in
the White Nile, the local people who
live close to the river complained of
stomach ache and intestinal troubles —
effects that were traced to the chemical
spraying. Harley (1989) also warned
that there was an environmental cost in
using herbicides. Residues of herbicides
in the water and sediments may affect
the aquatic environment and kill fish
directly or by reduced levels of
dissolved oxygen caused by decaying
weeds. The pity of it all is that the
chemical control treatment must be
20
continued indefinitely or the infestation
will regenerate from scattered plants
and seeds and the on-slaught on the
environment will continue.
I have never been completely against the
use of chemicals but it must be limited
to areas where they are absolutely
necessary and will do only a little
havoc. Such usage must also be borne
on tested experiments. The occurrence
of water hyacinth in Kainji Lake raises a
fresh problem for use of chemicals. The
Kainji Dam so important in the hydro-
electric supply of Nigeria must be
protected. In case of a major surge in
the dam area, a buffer zone can be
created around the dam. Appropriate
chemical can then be sprayed around
this buffer zone to keep the water
hyacinth in check and prevent it from
fouling up the dam. The dead weeds can
then be mopped up. Details of these
must be jointly examined by NEPA and
NIFFR before the exercise is initiated.
For the rest of the River Niger in
Nigeria, it must be a combination of
biological control, manual and mecha-
n ical harvesting, adequate monitoring
and burning up of the weeds when
certain parts of the River Niger dry up.
Utilisation as a Method of Control
Utilisation of water hyacinth for a wide
range of purposes has been suggested as
a method of checking and exploiting its
growth and spread. Jayanth (1987)
listed the foJiowing uses for water
hyacinth utilisation:
(a) as manure
(b) for producing processed feed for
pig, cattle and other animals.
(c) as a source of protein, gibberellic
acid etc.
(d) as a vegetable for human
consumption.
(e) for extraction for fibre or making
paper arid other products.
(f) as a renewable source of energy in
the form of biogas rich in methane.
(g) for waste water treatment.
Realising that fresh water hyacinth
contains nearly 95% water, most of
which has to be extracted before usage,
the economic viability of the economic
uses must be seriously considered, In
any case, utilisation must never be
considered as an option for controlling
the menace of water hyacinth.
DEVELOPMENT MANAGEMENT
STRATEGIES FOR WATER
HYACINTH CONTROL
Water hyacinth has become an
ECOWAS problem as a result of the
interdependece of the water network
which facilitates the spread of the weed
from one countly to another. Jointly
funded projects must therefore, be
established to carry out biological,
mechanical and chemical control in
21
representative areas in EGO WAS
countries where Water hyacinth is
causing problems. Such readily
identifiable projects will be between
Nigeria and Benin Republic to tackle
the problem in the coastal lagoons,
creeks and rivers. Projects to tackle the
water hyacinth in River Niger and
Kaiiiji Lake must be established
between Nigeria and Niger Republic.
The bilateral initiative, previously
carried out by the National Cornmttee
on Water hyacinth should immediately
be revived.
It must be emphasised that the main
emphasis should be on biological
control of water hyacinth with
interventions and use of mechanical and
chemical control where absolutely
necessary. The aquatic ecosystem must
be preserved as much as possible iii
dealing with the Nigeria problem. In
Nigeria, the National Committee on
Water Hyacinth should be revived and
made active. The National Committee
should ensure the setting up of Water
Hyacinth Control/Management Units at
the State and Local Government levels.
The Nigerian government must
immediately recognise water hyacinth
as a major ecological disaster.
ACKNOWLEGEMENTS
The author wishes to acknowledge
Prof. B,MB. Ladu, Director, National
Institute for Freshwater Fisheries
Research and the Organising Committee
for the kind invitation to present this
Keynote Address.
REFERENCES
Baruab, J.N. (1984). An environmentally sound
scheme for the management of water
hyacinth through its utilisation. Proc.
International Conference on Water
Hyacinth. Hydrabad, India, February 7-Il,
1983. pp 94— 125
Gopa, B. and Sharma, K.P. (1981). Water
hyacinth (Eichhornia crassipes) the most
troublesome weed of the world. Hindasia,
Delhi.
Harley, K.L.S. (1989). The management of
Water hyacinth with emphasis on biological
control, commonwealth Science Council
Publication, London. 44 pp
Jayanth, K.P. (1987). Biological control of
water hyacinth in India. Indian Institute of
Horticultural Research Tech. Bull. No.3
Khan, M.G.A. and Thyagarajan, G. (1988).
Water hyacinth: historical background and
CSC initiative. Proc. International
Workshop on Water hyacinth. Federal
Ministry of Science and Tethnology
Publication, Lagos. 19— 25.
Kusemiju, K.; O.T. Okusanya; T.V.1. Akpata
and J.A. Oyenekan (1985). Surge of water
hyacinth, Eichhornia crassipes (Mart) in
Lagos Lagoon and Badagry Creeks. Control
and eradication proposals to Lagos Chamber
of Commerce and Industry. 27 pp.
Kusemiju, K. and F.D. Chizea (1992), Report
on Water hyacinth infestation of River
Niger. Technical Report submitted to
Federal Ministry of Science and
Technology, Lagos. 13 pp.
Obeid, M. (1984). Water hyacinth, Eichhornia
crassipes (Mart) Soims in Sudan. Proc.
International Conference on Water
Hyacinth, Hydrabad, India. February 7
11, 1983.
Soerjani, M. (1984). Indonesia experience in
Water hyacinth utilization. Proc.
International Conference on Water
hyacinth, Hydrabad, India, February 7
11, 1983.
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DC.
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Defining an environmental development
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Water hyacinth in the 21st century: a keynote address

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Water hyacinth in the 21st century: a keynote address

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