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Survey of earthen fish ponds for aquatic weed problems in selected states of Southwestern Nigeria.

INTRODUCTION

Aquatic weeds are plants that have adapted to living in aquatic environment (salt water or fresh water. They are also referred to as hydrophytes or macrophytes. Worldwide fewer than 20 of approximately seven hundred aquatic plant species are considered as major weeds, of these economic important weeds were Eichhornia crassipes (water hyacinth), Pistia stratiotes (water lettuce), Salvinia nymphellula (water fern), Ceratophyllum demersum (ceratophyllum), Tyha australis (cattail), Nymphea lotus (waterlily), Cyperus papyrus (reed), Vossia cuspidata (vossia) and Phragmites karka (reed) have been incriminated as weeds of the aquatic systems in Nigeria (Hutchinson, G.E., 1975).

Weeds or macrophytes are critically important to many aquatic habitats. They provide spawning areas for adult fish, cover for smaller organisms, and they purify water in wetlands all over the world. Emergent weeds are also great stabilizers of shoreline areas and they provide a buffer zone, which helps clean the run-off entering the water body. But some are also a nuisance, including invasive species. The diagnostic features of aquatic weed basically support its rate of proliferation and as such makes it a menace to the aquatic environment. (Adekoya, B.B., 1997) (2001) reported that aquatic plant's infestation have a significantly adverse effect on the aquatic and terrestrial biodiversity of the affected location. Unmanaged population of this plant is capable of creating serious impacts that ripples through infested areas (Keddy, P.A., et al., 2007).

Aquatic weed causes lot of problem for fishermen and this include access to fishing sites which is usually difficult whenever there is infestation of the water by the weeds. In most cases, loss of fishing equipment when nets or wires become tangled in the root system of the weed leading to reduction in catch and subsequent loss of livelihood. In areas where fishermen get a meager living from their fishing occupation, this presents serious socio-economic problems. It was observed that about 45 million Kilograms of fish were annually lost due to aquatic weed infestation in the west Bengal of which the South-Western Nigeria is not left out (Charudattan, R., et al., 1994).

Aquatic weeds increase the surface areas of the rivers or lakes and this increase the rate water bodies lose water to the atmosphere by 3-5 times the normal rate due to accelerated evapotranspiration. Incidentally, evapotranspiration reduces the water volume in rivers, lakes, reservoirs, canal and river basins and this means that aquatic weed can cause drying up of rivers and ponds (Charudattan, R., 2001). Aquatic weeds impede transportation, irrigation and navigation by preventing free movement of fishes and other navigation vessels. Access to harbors and docking areas can be seriously hindered by mats of aquatic weeds. Ponds and rivers can become impassable as they clog up with densely intertwined carpets of the weed. It is also a serious hazard to lake transport as large floating mats of aquatic weeds clog up free waterways, sometimes leading to many of the Inland waterways being abandoned. This can have serious negative economic impact on the host communities (Davies, O.A., et al., 2009).

In addition to providing shelter for predator reptiles of fishes and other aquatic wild lives, the plant also harbors insect vectors of human and animal diseases. The diseases associated with the presence of the aquatic weed in tropical Countries are: Malaria, Schistosomiasis and lymphatic fillariasis. The Anophelis specie (female) of mosquito larvae thrive on the environment created by the aquatic weeds (Kitching, R.L., 2001). This means that there is a high risk of malaria, schistosomiasis and lymphatic fillariasis because of rapid growth of aquatic weeds e.g (Water hyacinth) in rivers and streams in communities within the South-Western Nigeria.

The continued inhabited infestation of water bodies by water hyacinth presents a long-term threat to the water bodies. The biodiversity (complex and mutual co-existence of other aquatic organisms for the balancing of the ecosystem), of an ecosystem can be lost entirely due to the invasion of the water body by aquatic weeds. It would spread over large areas and much of the water body could be eventually lost to land as other plants also begin to grow because of the new condition created by the presence of aquatic weeds. It also blots out light, endangers oxygen supply (Dissolved Oxygen (DO) reduction), slows down water flow and suppresses the growth of phytoplankton and algae with serious repercussions on biological productivity and diversity. Infestation by the weed produces an obnoxious smell that affect the color and taste of the water, thereby, impairing its quality and changing its chemistry; thus making it grossly unfit for human consumption, agricultural and industrial activities. Imbalance in the aquatic micro-ecosystem due to proliferation of water hyacinth also means that a range of flora and fauna that rely on a diversity of plants life for their existence will become extinct. Based on the high degree of reduction in the biodiversity of water invaded by aquatic weeds, there is disruption of socio-economic structure, food supply and health of up to several millions of people in South-Western Nigeria.

The impacts of aquatic weeds are numerous and their significance in the ecosystems, especially in large water bodies cannot be ignored. The weeds need to be managed prudently to allow sustainable exploitation and exploration of mitigating measures to minimize potential negative impact often associated with the massive proliferation. Aquatic weeds are highly susceptible to fast growth and their spread in water bodies is drastic. They are expected to be managed with high level of carefulness, due to the fact that their management must not lead to extinction of living organisms in the aquatic environment. The objectives of this study are; to determine whether aquatic weeds cause nuisance in earthen ponds within south-western Nigeria and to identify preventive and control measures undertaken by pond owners.

MATERIALS AND METHODS

The Study Area:

The research was carried out in four states within South-western Nigeria, namely; Ekiti state (5[degrees]E, 7.60N), Ondo state (5[degrees]E, 7[degrees]N), Oyo state (3[degrees]E, 8[degrees]N) and Osun state (4[degrees]E, 7[degrees]N) and these states were shown in Figure 1.

Population, sampling techniques and sampling size:

The study require a multi stage sampling technique to determine the number of respondent that will be interviewed, 80 earthen ponds were randomly selected from Ekiti, Oyo, Ondo and Osun state respectively. Table 1 shows the number of local government in each state where sampling was carried out. Questionnaires were administered to the selected farmers through individual approach.

Data collection:

Structured questionnaire and farm visit were used for data collection and twenty fish farmers making a total of 80 farmers' altogether was sampled. The sizes of pond in the entire farm visited across the each of the four states were of varying sizes. Farmers biodata information, years already spent in fish production, type of fish stocked, dimension of pond, source of water used were collected. Information on weed diversity, problems of aquatic weeds, method of pond owners used in combating aquatic weed problems was collected. In addition, the available source of information relating to weed control in their area was noted during the survey. Weed species in the ponds visited were identified and unidentified species were taken to the Ladoke Akintola University herbarium for proper identification. Data collected analyzed using descriptive statistics which include frequencies and percentages.

Results:

Characteristics of the respondent:

The characteristics of the farms sampled were shown in Table 2. Majority of ponds (81.3%) were newly constructed aged between 1-5 years, followed by those that has been in use for between 6-10 years (16.3%) and the least were 11-15 years old (2.5%). The source of labour for the farmers came from family members (57.5%), followed by hired labour (33.8%) and the least was contractual (8.8%) respectively. Family savings and loans from friends formed the major source of financing their farm enterprise with 47.5% and 23.8% of the respondent alluding to this fact respectively. The level of education of all farmers within the sampled sample was quite high as 52.5% had tertiary educational training while 36.3% of these farmers had secondary education. The least educational level is primary school which is just 11.3% of the sampled population. The year of establishment of the farms ranged between one and fifteen years with 1-5 (75.0%) followed by 6-10 years (21.3%) and the least 11-15 years (3.8%). The years spent in the fish production was in the same trends. The size of the ponds within the sampled population varied considerably. 33.8% of these ponds were between 2001 and 3000 [m.sup.3]. Next to this size was 3001-40000 [m.sup.3] which is 26.3% of the sampled population. Majority of the farmer stocked catfish while only few were involved in tilapia fish production (Table 3).

Infestation of aquatic weeds was higher during rainy season than the dry season and 90% of the respondent attested to this fact. The major aquatic weeds identified on the ponds of within the sampled population across the states include Eichhornia crassipes P. Beauv. (Water hyacinth), Nymphea lotus Linn. (Water lilly), Pistia stratiotes Linn. (Water lettuce), Tyha australis Pers. (cattail), Leersia hexandra Sw. and Cyperus spp (sedges). The most prevalent weed across the farms was sedges (Cyperus spp). Infestation of aquatic weeds posed different challenges to the farmers (Table 3). Among the problems associated with aquatic weeds on their ponds were prevention of aeration (65.5%), harboring of fish fingerlings and juvenile predators (55.0%), reduction in production (42.5), prevention of water flow (26.3%), reduced profit (22.0%), water pollution (21.3), reduction in water level (17.5) and wastage of feed (8.8%) (Table 4). Manual weed control was employed by majority of the farmers (73.8%) and this was followed by the use of herbicide (25.0%) and only 10% of the farmers use biological control measure to abate the problems of aquatic weeds on their ponds (Table 4). The major source of water used for ponds activities include boreholes and natural source (spring/stream) and this is shown in Table 5. Farmers associations provide good sources of information to the farmers when compared with other information sources like radio, television and extension agents.

Discussion:

The age the fish ponds in the different farms sampled is an indication that the larger percentage of the farmers are relatively new in fish production. Also, different sizes of these ponds managed by many of the farmers could be as a result of limited fund and size of capitals available to these farmers since majority of them sourced for their capital from their personal savings. All of these factors notwithstanding, these farms were not free from all attendant problems that were common to any farming enterprise among which is the problems of weed management in their fish ponds.

The major aquatic weed species identified during this survey which includes Eichhornia crassipes, Nymphea lotus, Pistia stratiotes, Tyha australis, Leersia hexandra and Cyperus spp were listed among the worst weed in the aquatic environment worldwide (Anonymous, 2015). In view of this fact, more effort are required in checking the proliferation of these weeds to remain below the economic threshold and reduce the possibility of invading many of the Nigeria freshwater bodies which can lead to huge economic loss to the nation as a whole. Generally, Cyperus spp, Nymphea lotus and Eichhornia crassipes were the main aquatic weed affecting the sampled ponds and this was in agreement with the work of (Kusemiju, K.,1988) who reported Eichhornia crassipes as one of the major aquatic weed that has clogged most of our intricate system of water ways in Nigeria.

Moreover, the farmers revealed that these aquatic weeds harbor many dangerous animals like snake which can bite the farmers and if good medical assistance is not available may lead to eventual death of such farmer. Other problems associated with weeds in ponds include disturbance of physicochemical components of the water thereby impairing the growth of fish, harboring predators for juvenile fish, feed wastage and eventually increase the cost of production thereby reducing the profit margin of the farmers. As a result of preponderance aquatic weed infestation, silting up of ponds will be imminent for such pond owner and the stocking capacity of such pond will be drastically reduced. During the life span of ponds with aquatic weeds infestation, decaying of these weeds might increase the organic load of the pond thereby creating imbalance in the nutrients status of such pond and more biological components of the pond ecosystem will be impacted. It was also observed that respondent majorly employ manual control method in combating aquatic weed infestation in their ponds and only few attempted the use of herbicide for fear of adverse effect on their fish production.

Family labour was used for all exercises on the farm and respondents were able to gather information mainly from farmers' associations. Only few people interacted with extension agents for agricultural information and this was similar to the observation of (Ofuoku, A.N., et al., 2008) that only few farmers gather information from extension workers and that majority of farmers relied on NGOs and farmer association for information on fish farming.

It was observed that many of the respondents are literate and this factor enabled them to the appropriate method of aquatic weed control and chooses a preferable management procedure that suits their peculiar situation. This implies that educated people are into fish farming which agrees with the work of (Dereje, H., 2006) that, the high level of literacy of farmers will enable them to respond to innovations and have a better managerial ability.

In this study, many of the respondents sourced for capital from the family savings; this revealed fish farming require financial support to boost food production in Nigeria to feed her teeming population. It is important that government agencies responsible for agricultural finance are encouraged to look into this sector which was in agreement with the work of (Omotoyin, B.O., 2007) who affirmed that most farmers lack adequate capital to either operates their farms profitably or expands them, which may be due to unwillingness of financial institution to grant loan to the farmers or high interest rate of loan when given.

Conclusion:

The surveys reveal aquatic weed problems in cultures fish production is an important factor to consider in pond construction and management. Emergent aquatic weed species like sedges if not properly managed can in no small way affect the productivity of any pond and invariably reduce the profitability of fish production in South western Nigeria. Education is an important key element in the adoption of innovation in agricultural production in Nigeria.

REFERENCES

Hutchinson, G.E., A Treatise on Limnology, 1975. Limnological Botany. New York: John Wiley 3.

Adekoya, B.B., 1997. Chemical control of water hyacinth eichhornia crassipes) at ere, ogun state, nigeria: implications for aquatic and terrestrial biodiversity conservation. Ogun State Agricultural Development Programme, PMB 2122, Abeokuta, Nigeria.

Keddy, P.A., D. Campbell, T. McFalls, G. Shaffer, R. Moreau, C. Dranguet and R. Heleniak, 2007. The wetlands of lakes Pontchartrain and Maurepas: past, present and future, Environmental Reviews, 15: 1-35.

Charudattan, R., J.T. Devalerio, V.J. Prange, R.R. Baker and P.E. Dunn, 1994. Special problems associated with aquatic weed control, Journal of Aquatic Plant Management, 32: 33-36.

Charudattan, R., 2001. Are we on top of aquatic weeds? Weed problems, control options, and Challenges. A talk presented at an international symposium on the World's Worst Weeds, organized by the British Crop Protection Council, Brighton, United Kingdom.

Davies, O.A., J.F.N. Abowei and C.C. Tawari, 2009. Phytoplankton community of elechi creek, Niger Delta, Nigeria-a nutrient polluted tropical creek, Am. J. Appl. Sci., 6(6): 1143-1152.

Kitching, R.L., 2001. Foodwebs in phytotelmata: "Bottom- Up" and "Top-Down" explanations for community structure. Annu. Rev. Entomol., 46: 29-760.

Anonymous, 2015. Understanding Invasive Aquatic Weeds. The Aquatic Plant Management Society in cooperation with the Florida Fish and Wildlife Conservation Commission / Invasive Plant Management Section and the University of Florida / IFAS, Center for Aquatic and Invasive Plants, (2010) http://plants.ifas.ufl.edu/node/688.

Kusemiju, K.,1988. strategies for effective management of water hyacinth in the creeks and lagoons of south western Nigeria. In Oke, O. L, A. M. A. Imevbore and T. A. farin OP cit, pp: 39-45.

Ofuoku, A.N., G.N. Emah and B.E. Itedjere, 2008. Information utilization among rural fish farmers in central agriculcutural zone of Delta State, Nigeria, World J. Agric. Sci., 4(5): 558-564.

Dereje, H., 2006. Assessment of farmers'evaluation criteria and adoption of improved bread wheat varieties in Akaki, central Ethiopia. Unpublished M.Sc. Thesis presented to school of Graduate studies Alemaya University, Ethiopia.

Omotoyin, B.O., 2007. Introduction to Fish Farming in Nigeria. Ibadan University Press, Publishing House, University of Ibadan, Ibadan, Nigeria.

(1) Gabriel Olulakin Adesina, (2) Kasali Amofe Adelasoye and (3) Felix Abayomi Ogunmokun

(1,2,3) Department of Crop and Environmental Protection, Faculty of Agricultural Sciences, Ladoke Akintola University of Technology, P. M. B. 4000, Ogbomoso, Nigeria

Received 12 March 2015; Accepted 28 August 2015; Available online 22 September 2015

Address For Correspondence:

Gabriel Olulakin Adesina, 3Department of Crop and Environmental Protection, Faculty of Agricultural Sciences, Ladoke Akintola University of Technology, P. M. B. 4000, Ogbomoso, Nigeria

Table 1: List of Local Government survey for effect
of weed on earthen ponds

State   Local Government Area   Frequency   Percentage

Ekiti                           20          25
        Ido osi                 3           3.8
        Ado                     3           1.3
        Moba                    4           5.0
        Ifelodun                3           3.8
        Oye                     2           2.5
        Ijero                   2           2.5
        Ilawe                   1           1.3
        Emure                   1           1.3
        Ilejemeje               2           2.5
        Omuo                    1           1.3
Osun                            20          25
        Ife south               3           3.8
        Ife East                4           5.0
        Ede North               1           1.3
        Ifelodun                1           1.3
        Ilesa East              2           2.5
        Osogbo                  2           2.5
        Irepodun (Osun)         2           2.5
        Iwo                     2           2.5
        Olorunda                1           1.3
        Isokan                  1           1.3
        Ife Central             1           1.3
Oyo                             20          25
        Ogbomoso North          1           1.3
        Ogbomoso South          1           1.3
        Saki East               3           3.8
        Saki West               1           1.3
        Suurulere               3           3.8
        Olorunsogo              1           1.3
        Egbeda                  2           2.5
        Oyo East                2           2.5
        Ibadan North            1           1.3
        Ibadan East             1           1.3
        Ibarapa North           3           3.8
        Ogo Oluwa               1           1.3
Ondo                            20
        Ile oluji               3           3.8
        Oke igbo                2           2.5
        Ondo West               1           1.3
        Akure North             1           1.3
        Ilaje                   2           2.5
        Ondo West               1           1.3
        Akure North             2           2.5
        Akure South             1           1.3
        Idanre                  2           2.5
        Akoko North west        1           1.3
        Akoko North east        1           1.3
        Suurulere (Ondo)        1           1.3
        Okitipupa               1           1.3
        Owo North               1           1.3
Total                           80          100

Table 2: Socioeconomic characteristic of the
respondents

Variables               Frequency   Percentage

Age of the pond
1-5 years               65          81.3
6-10 years              13          16.3
11-15 years             2           2.5
Total                   80          100.0
Source of labour
Hired                   27          33.8
Family                  46          57.5
Contractualative        7           8.8
Total                   80          100.0
Source of capital
Loan from friends       19          23.8
Family saving           38          47.5
Loan from cooperative   23          28.8
Total                   80          100.0

Education level
Primary school          9           11.3
Secondary school        29          36.3
Tertiary education      42          52.5
Total                   80          100.0
Farm establishment
1-5 years               60          75.0
6-10 years              17          21.3
11-15 years             3           3.8
Total                   80          100.0
Year of production
1-5 years               63          78.8
6-10 years              15          18.8
11-15 years             2           2.5

Table 3: Dimension of ponds and types of fish
stocked

Variables              Frequency   Percentage

Size of the pond       1           1.3
Below 1000 [m.sup.3]   12          15.0
1001-2000 [m.sup.3]    27          33.8
2001-3000 [m.sup.3]    21          26.3
3001-4000 [m.sup.3]    6           7.5
4001-5000 [m.sup.3]    4           5.0
5001-6000[m.sup.3]     1           1.3
6001-7000 [m.sup.3]    6           7.5
7001-8000 [m.sup.3]    1           1.3
8001-9000 [m.sup.3]    1           1.3
9001-10000 [m.sup.3]   80          100.0
Total
Catfish stocked
1--1000                10          12.5
1001-2000              28          35.0
2001-3000              15          18.8
3001-4000              10          12.5
4001-5000              4           5.0
Above 5000             13          16.3
Total                  80          100.0
Tilapia stocked
1-1000                 19          23.8
1001-2000              6           7.5
2001-3000              2           2.5

Table 4: Seasonal variation, weed diversity, problems
associated with weed and its control.

Variables                         Frequency   Percentage

Weed season infestation
Dry                               5           6.3
Rain                              72          90.0
Type of weeds
Nymphea lotus                     1           1.3
Eichhorrnia crassipes             4           5.0
Pistia stratiotes                 2           2.5
Typha australis                   1           1.3
Cyperus spp                       21          26.3
Leersia hexandra
Problems associated with weeds
Prevention of water flow          21          26.3
Prevention of aeration            52          65.5
Water pollution                   17          21.3
Harbor predators                  44          55.0
Reduce water level                14          17.5
Reduce level of fish production   34          42.5
Reduce income                     18          22.0
Wastage of food                   7           8.8
Weed control method
Physical control                  59          73.8
Chemical control                  20          25.0
Biological control                8           10.0

Table 5: Source water to earthen pond and
feedback to the farmers.

Variables             Frequency   Percentage

Source of water
Bore hole             31          38.8
Spring                32          40.0
Stream                27          33.8
Source of feedback
Extension agent       12          15.0
Radio                 9           11.3
Television            4           5.0
Farmers association   44          55.0
Friends               10          12.5
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Article Details
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Author:Adesina, Gabriel Olulakin; Adelasoye, Kasali Amofe; Ogunmokun, Felix Abayomi
Publication:American-Eurasian Journal of Sustainable Agriculture
Article Type:Report
Geographic Code:6NIGR
Date:Jul 1, 2015
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