99

Journal of Aquatic Sciences 27 (2): 99 – 111 (2012)

ECOLOGICAL STATUS OF OWAN RIVER, SOUTHERN NIGERIA USING AQUATIC

INSECTS AS BIOINDICATORS

A. O. EDEGBENE AND F. O. ARIMORO

Department of Animal and Environmental Biology, Delta State University, P.M.B. 1, Abraka, Nigeria.

ABSTRACT

Aquatic insects are among the most directly affected and vulnerable organisms with respect to surface water

pollution and used as bioindicators of water quality. The composition, distribution and diversity of aquatic

insects in Owan River, southern Nigeria were assessed and influence of different physico-chemical factors were

explored at four designated stations. Dissolved Oxygen (DO) (5.2 -7.8mgl-1

) and biochemical oxygen demand

(BOD) (1.64–2.60 gl-1

) showed that the river was slightly aerated. A total of 38 taxa comprising of 1896

individuals were recorded during the study. Station 3 accounted for the highest number of individuals (530)

while Station 1 had the lowest number of individuals (410). Order Diptera was the most ubiquitous insect taxa

in the study with nine (9) species while order Plecoptera was sparingly represented by one (1) species Neoperla

sp. Diversity index revealed that taxa richness (d) and diversity (H) were highest in Station 1 while Station 3

accounted for the lowest taxa richness and diversity. Ephemeroptera Plecoptera and Trichoptera (EPT) were

highest in Station 3 and Station 1 had the least EPT value. Station 3 showed the lowest chironomid richness

while Station 4 had the highest. The composition, distribution and diversity of aquatic insects in Owan River

were affected by the nature of the streambed and physicochemical variables examined. Owan River can be said

to be slightly clean water body rich in EPT organisms.

Key Words: EPT organisms, bioindicator, physico-chemical parameters, Owan River, Southern

Nigeria.

INTRODUCTION

Aquatic insects are among the most

directly affected and vulnerable organisms with

respect to surface water pollution and constitute

an important component of biodiversity in

running water (Verneaux et al., 2003). The

importance of aquatic insects in indicating the

ecological status of lotic waters has been

neglected in the past (Karr, 1991), especially

when compared to the popular environmental

indicators, such as diatoms, fish and birds

(Bauernfeind and Moog, 2000; Abebe et al.,

2009). Recently, biomonitoring studies is

gradually shifting to the use of Ephemeroptera,

Plecoptera and Trichoptera (EPT) in Nigeria

(Atobatele et al., 2005; Arimoro and Ikomi,

2009) and elsewhere in Brazil (Vera et al.,

2007). This recent upsurge of the use of the

aquatic insect most especially the EPT as

environmental indicators is due to the fact that,

they are diverse, sensitive and respond to both

natural and man-induced changes in the

environment (Ndaruga et al., 2004). This

survey on the ecological status of Owan River

will provide vital information for decision

makers and environmental managers to take

100

accurate and justifiable actions as well as

evaluating the effectiveness of legislative rules

already in place (Bauernfeind and Moog,

2000). This study may probably be the first

biomonitoring investigation using aquatic

insects as bioindicators in Owan River,

Southern Nigeria. The study is aimed at

determining the composition, distribution and

diversity of aquatic insects in Owan River in a

view to using them to ascertain the ecological

status of the river.

MATERIALS AND METHODS

Description of the study area

Owan River is a freshwater body in the

northern part of Edo State, southern Nigeria. It

lies between latitude 5o.43’- 6

o. 00

’N and

longitude 6o.48’ – 7

o. 18’E of the equator

(Fig.1). It is a municipal river flowing across

two Local Government Area (Owan East and

Owan West ) Local Government Area of Edo

State. The river takes it source from Otuo in

Owan East Local Government Area and flow

southward through major towns like Afuze,

Ogute, Sabongidda-Ora, Uzebba were it joins

River Ose. The study area shows the

characteristics tropical climate of two distinct

seasons, the wet season (May- October) and the

dry season (November – April). For the

purpose of this study four marked out stations

were chosen proceeding downstream from the

source of the river. Station 1 was located about

18km, from the river source at Ogute-Emai,

station 2 was located 3km from station 1 at

Evbiamen-Emai, station 3 was located 5km

from station 2 at Okpokhumin-Emai while

station 4 at Ojavun, another 5km from station 3.

Physico-chemical sampling

Water samples were collected monthly

from each station for 12 months (September,

2010 – August, 2011). Water temperatures

were measured in-situ at each sampling time

using mercury-in-glass thermometer. Flow

velocity was measured in midchannel on three

occasions by timing a float (average of three

trials) as it moved over a distance of 10m

(Gordon et al., 1994). Water depth and width

were measured in the sample area using a

calibrated stick. Dissolved oxygen (DO),

Biochemical oxygen demand (BOD), pH and

Alkalinity were determined according to APHA

(1992) method. Phosphate, sulphate and nitrate

were measured spectrophotometrically after

reduction with appropriate solutions APHA

(1992). Substratum composition in each 25m

sampling reach was estimated visually as

percentage of silt, loam and sand (Ward, 1992).

Aquatic insects sampling

Kick samples of macroinvertebrates

were collected monthly (September, 2010 –

August, 2011) with D-frame net (800m mesh)

within an approximately 25m wadeable portion

of the river. Four 3-min samples were taken on

each sampling visit to include all different

substrate and flow regime zones. Samples

collected from the net were preserved in 70%

ethanol and transferred to the laboratory. At the

laboratory samples were washed in a 500m

mesh sieve to remove sand and aquatic insects

were then picked from the substrate with aid of

a forceps and microscope. All animals were

enumerated and identified under a binocular

dissecting microscope following Durand and

Leveque (1981); Gerber and Gabriel (2002) and

Merritt and Cummins (1996).

101

Data analysis

Community attributes and

physicochemical parameters of the sampling

stations were compared using repeated

measures ANOVA. Fixed effect ANOVAs

were performed using dates as replicates on

log(x+1) transformed data. Significant

ANOVA (p<0.05) were followed by Turkey

Honest significant difference (HSD) tests to

identify differences between stations means.

The components metrics used in assessing the

ecological status of Owan River were species

composition and community structure. Taxa

richness (Margalef index), diversity (Shannon-

Wiener index), evenness and dominance

indices were calculated using the computer

BASIC program SP DIVERS (Ludwig and

Reynolds, 1988).

RESULTS

Physicochemical factors

The mean, standard deviation, minimum

and maximum value, ANOVA (F-values) of

physical and chemical parameter of the four stations

sampled in Owan River are summarized in (Table

1). Water temperature, flow velocity, water depth,

width, biochemical oxygen demand (BOD), pH,

phosphate, nitrate and alkalinity were significantly

different among the sampling stations (p<0.05).

Dissolved oxygen (DO) was significantly different

(p<0.05) among the sampling months but not

significantly different (p>0.05) among the sampling

stations. Water temperature was greatest in station

1 and lowest in Station 3. Dissolved oxygen value

range between 5.3 and 8.0 mgl-1

which was the

greatest among the stations sampled and the lowest

range of BOD (1.64 – 2.5 mgl-1

) were recorded in

Station 3 respectively.

N

5O30 6

O00 6

O30

6O30 6

O00 5

O30

8O00

7O30

6O30

6O00

8O00

7O30

6O30

6O00

NIGERIA

STUDY AREA

Study Stations

Major Towns

Key O

WAN

RIV

ER

O

ES

RIV

ER

OTUO

EH

OR

RIV

ER

UZEBBA

SABO-ORA

AFUZE

OVBIOWUN

OGUTE (ST. 1)

EVBIAMEN (ST. 2)

OKPOKHUMI (ST. 3)

OJAVUN (ST. 4)

N

Figure 1: Map of the study area showing the sampling stations

102

Aquatic insect composition and distribution

Table 2 shows the summary of composition

and distribution of aquatic insects in the study area.

A total of thirty eight (38) taxa of aquatic insects

comprising of 1896 individuals were recorded

during the present study. The total number of taxa

and individuals present at station 1, 2, 3 and 4 were

38 (410), 38 (520), 32 (530) and 35 (436)

respectively.

The order Ephemeroptera was represented by seven

(7) taxa and all the species were distributed in the

four stations sampled except Caenis aenum which

was absent in station 4. Tricorythus sp. was

sparingly present in all the stations. Odonata and

Coleoptera were both represented by 6 and 5 taxa

respectively. Hemiptera, Plecoptera and

Trichoptera were represented by 6, 1 and 4 taxa

respectively. The order plecoptera was the least in

term of species composition and distribution.

Diptera was the most ubiquitous insects in Owan

River with nine (9) species and the family

Chironomidae accounted for 5 species of the nine

Diptera species, being the family that had the

highest number of species. Of all the individuals

collected, stations 1,2,3 and 4 accounted for 21.6%,

27.4%, 27.9% and 22.9% respectively (fig. 2).

Fig. 2: percentage distribution in density of Aquatic Insects in Owan River

Diversity, taxa richness and dominance of

aquatic insects in Owan River

Table 3 shows the summary of the

diversity, taxa richness and dominance indices

calculated for the four stations. The taxa richness

(d) was highest in Station 1 (6.2) followed by

Station 2 (5.9) while Station 3 accounted for the

least (4.9). Shannon diversity (H) was highest in

station 1 (1.42) closely followed by station 2 (1.40)

while Station 3 (1.29) had the least. Maximum

species diversity was higher in Stations 1 and 2 with

Hmax value of (1.58) each while Station 3

accounted for the least maximum species diversity.

Evenness were the same in Stations 1 and 2 (0.89)

closely followed by Station 4 (0.88) with Station 3

having the least evenness value of 0.85. Simpson

dominance was lowest in Station 1 (0.037) and

highest in Station 2 (0.054). Stations 3 and 4

accounted for 0.048 and 0.046 dominance value

respectively. The Ephemeroptera, Plecoptera and

Trichoptera (EPT) richness was highest in Station 3

(39.2%), followed by Station 2 (28.5%). Station 1

accounted for the lowest EPT (24.6%). The

Chironomid richness was lowest in Station 3 (3.8%)

and highest in Station 4 (20.9%).

st 1;

21.60%

st 2;

27.40%st3;

27.90%

st4;

22.90%

103

Table 1: Environmental factors measured at four sampling stations of Owan River (September 2010 – August 2011).

Parameter Station 1 Station 2 Station 3 Station 4 Months Stations

F-

values

P- value F-

values

P- value

Features of the reach Unconstrained Unconstrained Unconstrained Unconstrained

Riparian vegetation Native Native Native Native

Land use Agriculture Forestry Forestry Agriculture

Substrate type Sand/loam Sand/loam Sand/stones Sand/loam

Water Temperature (oC) 26.61+0.96

(24.2-26.8)

25.01+1.20

(23.2-26.8)

24.85+0.76

(24.0-26.2)

26.05+1.24

(24.5-27.6)

24.7 P<0.05 23.2 P<0.05

Flow velocity (m/s) 0.29+0.15

(0.10-0.48)

0.24+0.14

(0.08-0.44)

0.34+0.18

(0.10-0.58)

0.25+0.22

(0.076-0.92)

50.9 P<0.05 31.7 P<0.05

Water depth (m) 1.27+0.51

(0.63-1.84)

1.33+0.63

(0.54-2.05)

1.04+0.42

(0.47-1.52)

1.28+0.67

(0.41-2.00)

77.2 P<0.05 8.8 P<0.05

Width (m) 7.27+1.42

(5.81-9.23)

6.83+1.34

(5.12-8.43)

7.09+1.57

(5.01-9.14)

6.76+1.74

(4.98-9.25)

69.3 P<0.05 4.7 P<0.05

Dissolved oxygen (DO) (mgl-1

) 6.28+0.77

(5.2-7.6)

6.32+0.86

(5.3-7.8)

6.3+0.92

(5.3-8.0)

6.23+0.79

(5.3-7.4)

132.4 P<0.05 0.97 P>0.05

Biochemical Oxygen

Demand (BOD5) (mgl-)

2.05+0.12

(1.84-2.2

2.11+0.22

(1.78-2.5)

2.16+0.27

(1.64-2.5)

2.14+0.28

(1.80-2.60)

19.2 P<0.05 2.9 P<0.05

pH 6.95+0.38

(6.4-7.6)

6.89+0.45

(6.3-7.6)

6.68+0.41

(6.1-7.3)

6.78+0.49

(6.2-7.6)

50.0 P<0.05 11.3 P<0.05

Phosphate (mgl-1

) 0.038+0.0063

(0.03-0.46)

0.049+0.0042

(0.04-0.58)

0.057+0.0044

(0.05-0.062)

0.057+0.0046

(0.05-0.063)

5.7 P<0.05 80.7 P<0.05

Sulphate (mgl-1

) 9.29+0.104

(9.1-9.5)

8.23+0.45

(7.8-9.2)

8.55+0.42

(8.0-9.2)

9.03+0.29

(8.58-9.4)

1.4 P>0.05 23.1 P<0.05

Nitrate (mgl-1

) 0.13+0.019

(0.1-0.16)

0.34+0.33

(0.060-0.75)

0.32+0.31

(0.06-0.71)

0.33+0.31

(0.06-0.73)

4.05 P<0.05 177.5 P<0.05

Alkalinity (mgl-1

) 30.39+0.60

(29.7-31.4)

37.63+0.81

(36.5-38.8)

37.86+0.91

(36.4-38.9)

30.66+1.43

(28.7-32.8)

15.4 P<0.05 905 P<0.05

Note: Values are means+ standard deviation. Maximum and minimum values in parenthesis. The F - values indicate ANOVA and P - value

indicating the level of probability.

Table 2: Composition and distribution of Aquatic insects in Owan River (September 2010 –

August 2011).

Stations

Taxa/order Family Species 1 2 3 4

Ephemeroptera Baetidae Afrobaetodes sp. 12 23 36 5

Baetis sp. 10 7 18 4

Cloeon sp. 7 9 14 2

Centoptilum sp. 2 8 11 3

Heptageniidae Afronurus sp. 8 18 22 11

Caenidae Caenis aenum 2 3 7 0

Tricorythidae Tricorythus sp. 1 2 1 3

Odonata Macromidae Macromia sp. 13 9 15 3

Gomphidae Ictinogomphus

sp.

9 10 17 7

Lestinogomphus

sp.

5 11 14 8

Libellulidae Libellula sp. 28 32 58 17

Aeschnidae Aeschna sp. 13 13 21 6

Lesticidae 5 2 0 7

Coleoptera Hydrophilidae Hydrophilus sp. 10 12 2 14

Gyrinidae Gyrinus sp. 13 18 26 18

Dysticidae Dytiscus sp. 25 29 33 22

Elmidae Promerisia sp. 8 7 2 16

Chrysomelidae Donacia sp. 4 2 1 0

Hemiptera Nepidae Nepa sp. 28 34 16 33

Naucoridae Naucoris sp. 18 22 52 18

Belostomatidae Appasus sp. 16 16 4 21

Gerridae Gerris sp. 29 53 38 19

Notonectidae Notonecta sp. 5 9 1 12

Hydrometridae Hydrometra sp. 3 3 2 0

Plecoptera Perlidae Neoperla sp. 29 22 16 11

Trichoptera Economidae 12 16 7 45

Hydroptilidae Leptonema sp. 1 1 0 14

Lemnephilidae Stenophylax sp. 1 8 3 1

Hydropsychidae Hydropsyche sp. 16 31 73 25

Diptera Chironomidae Chironomus

transvaalensis

16 11 4 17

Chironomus

fractilobus

12 16 0 1

Pentaneura sp. 9 11 0 10

Polypedilum sp. 8 9 3 11

Clinotanypus sp. 1 1 0 3

Tipulidae Tipula sp. 9 11 7 8

Syrphidae Eristalis sp. 7 12 0 19

Culicidae Culex sp. 8 8 3 12

Tabanidae Tabanus sp. 7 11 3 10

Total 410 320 530 436

105

Table 3: Diversity and other indices of aquatic insects in the study stations of Owan River.

Stations

1 2 3 4

No. of taxa 38 38 32 35

No. of individuals 410 520 530 436

Margalef’s index (d) 6.2 5.9 4.9 5.6

Shannon weiner index (H) 1.42 1.40 1.29 1.36

Maximum species diversity

(Hmax)

1.58 1.58 1.51 1.54

Evenness index (E) 0.89 0.89 0.85 0.88

Simpson’s dominance (D) 0.037 0.054 0.048 0.046

% EPT 24.6 28.5 39.2 28.4

% Chironomids 18.8 17.3 3.8 20.9

106

DISCUSSION

The physicochemical qualities of water

and immediate substrate are important factor

determining the abundance and distribution of

benthos richness including aquatic insects

(Dance and Hynes, 1980). This study area

showed two characteristic seasons, a dry season

(November to April) and raining season (May

to October) typical of the tropical countries

(Imoobe and Oboh, 2003). Flow velocity is a

function of the amount and width of the water

channel (Nelson and Liebermann, 2002). There

was a great distinction in the flow velocity of

Owan River. Station 4 recorded the highest

value of flow velocity and this may be

attributed to surface run-off and storm water

from town around the station, probably due to

few tree cover which may not be good enough

to act as wind and erosion breaker. Flow

velocity value was higher in the rainy seasons

than in the dry season. This may be due to run-

off of debris from nearby farmland, increase in

water volume during the raining months when

compared with the dry months. This finding

coincides with similar studies in some water

bodies in Niger Delta (Ikomi et al., 2003 and

Olomukoro and Egborge, 2004).

Dissolved oxygen concentration of the

stations sampled showed that it was well

aerated sites. Dissolved oxygen ranged from

5.2 to8.0 mgl-1

in this study area. Similarly,

Ikomi et al. (2003), Olomukoro and Egborge

(2004) reported same in Warri River, Delta

State, Nigeria. This they attributed to the

increased primary production of macrophytes

and the level of organic suspended solids. The

value of DO recorded in this study most

especially in Station 3 may be attributed to the

less human activities carried on in the river.

The biochemical oxygen demand (BOD) value

was highest in station 4, indicating the

deteriorating nature of this station as a result of

more human impact on the water body here

when compared to other stations. According to

Adakole and Anune (2003), streams can be

classified using BOD as follows: unpolluted

(BOD < 1.0 mgl-1

), moderately polluted (BOD

between 2 and 9 mgl-1

) and heavily polluted

streams (BOD > 10 mgl-1

). So the BOD value

(1.64 – 2.6m gl-1

) recorded in this study reveals

that the river is not heavily polluted irrespective

of few human activities on the river. Generally,

the results of the physicochemical parameters

measured in this study were within the range

permissible for the growth and survival of most

macro-invertebrates including aquatic insects

Cheshire et al. (2005).

Thirty eight (38) taxa of aquatic insects

were identified, with Ephemeroptera (7),

Odonata (6), Coleoptera (5), Hemiptera (6),

Plecoptera (1), Trihcoptera (4) and Diptera (9).

This is in consonant with 57 taxa of aquatic

insects recorded by Arimoro and Ikomi (2009)

in Upper Warri River, Niger Delta, Nigeria.

Ephemeroptera represented by seven (7) taxa

shows that the density of this order is high in

the present study area. Similarly, studies in

other part of Nigeria has reported the density of

Ephemeroptera as very high among the

macrobenthic community (Ogbeibu and

Oribhabor, 2002; Arimoro and Ikomi, 2009 and

Arimoro and Muller, 2010). The family

Baetidae was well represented by four taxa

with Afrobaetodes sp. being the preponderant

species of the family Baetidae in all the

stations. This may be attributed to the relatively

high flow velocity in this study area. Arimoro

and Ikomi (2009) had earlier implicated the

high density of Ephemeroptera to relative high

flow velocity in the study they conducted in

Warri River, Niger Delta, Nigeria. Also, the

Owan River can be said to be slightly

deteriorating because of the over dispersion of

the family Baetidae in all the stations sampled.

Station 3 had the highest number of individuals

in the study as expected because of the less

human activities carried out in this station when

compared to other stations. The family

Caenidae represented by Caenis aenum was

also highest in Station 3 and absent in Station 4.

This finding agrees with study by Arimoro and

107

Muller (2010) in Orogodo River, southern

Nigeria. Baetidae and Caenidae in this study

can be proposed as an indicator of water quality

and ecosystem health primarily because of their

presence in all the stations except station 4

were Caenidae was not recorded, probably due

to the numerous human activities that may have

hamper its presence in this station. Station 3

also had the highest number of Caenidae.

Though, the two families (Baetidae and

Caenidae) were slightly reduced in Stations 1, 2

and 4 probably due to the slight impact of

human activities in these stations. The genera

Baetis and Caenidae from earlier studies have

been reported to be tolerant of organic pollution

(Timm 1997; Menetrey et al., 2008). However,

in this study, Baetidae and Caenidae had higher

representative in station 3, the undisturbed

water, contrary to the earlier report by Timm

1997 and Menetrey et al., 2008). Coleoptera

was represented by five (5) families. This

shows the high density of the group in Owan

River. Abundance of Coleoptera like Gyrinus

sp. and Dytiscus sp. in water body indicates the

water is relatively free from gross pollution

(Arimoro et al., 2007). So, this present study

recording a high number of Coleoptera shows

that the river is slightly clean. Related studies

conducted in similar freshwater bodies in

Nigeria (Edokpayi et al., 2000, Edema et al.,

2002; Ikomi et al., 2005) and elsewhere (Rueda

et al., 2002; Walsh et al., 2002 and Nelson and

Roline, 2003) have associated the presence of

these organisms in a site to clean water

conditions. Also, beetles particularly

Hydrophilids and Dytiscids can renew their

oxygen supply directly from the atmosphere,

they are probably unaffected by oxygen

depletion (Merrit and Cummins, 1996).

Trichoptera was present in all the

stations except the taxa Leptonema sp. which

was sparingly represented in Stations 1 and 2,

absent in Station 3 and constituting 14

individuals in Station 4, which was slightly

impaired had the highest number of Leptonema

sp., which shows that Leptonema sp. is tolerant

of pollution. According to Arimoro et al.

(2011), the Caddis flies (Trichoptera) are

tolerant to a wider range of conditions than

Ephemeroptera and Plecoptera, having different

feeding strategies and using different trophic

resources. The family Hydropsychidae

(Hydropsyche sp.) was the dominant species in

all the aquatic insects sampled in Owan River.

Reports in some rivers in southern Nigeria are

in consonants with this present findings

(Ogbogu and Akinya, 2001 and Umeozor,

2004). Also, the preponderant of Hydropsyche

sp. may also be attributed to relatively high

flow velocity in the study area. This is similar

to the other studies in Nigeria (Ikomi et al,

2005) and elsewhere (Griffith et al., 2001).

Plecoptera made up a very small proportion of

the total insects composition, with only one

species recorded, Neoperla sp. Other studies

elsewhere have reported several stone fly

species. For instance, Bispo et al. (2002)

reported a total of nine species belonging to

three genera, in a mountainous area of Central

Brazil, while Popijac and Sivec (2009)

recorded 15 stonefly species in the Plitvica

lakes and along the Catina River in Croatia.

Generally only the genus Neoperla occurs

throughout tropical Africa (Fochetti and Tierno

de Figueroa, 2008).

The Diptera was highly represented by

9 species and most of the Chironomids

(Chironomus fractilobus, Pentaneura sp. and

Clinotanypus sp.) were absent in Station 3.

Also, the Syrphidae (Eristalis sp.) was not

present in Station 3. This may be as a result of

the unperturbed nature of Station 3 when

compared to other stations, because these

species are known to be tolerant of pollution

(Solimini et al., 2003, Rueda et al., 2002 and

Ravera, 2001). Generally, the Chironomids

were not that abundant in all the stations

sampled. This point to the fact that the water is

slightly free from gross pollution unlike other

related research conducted by Arimoro et al.

(2007) reported Chironomids composition of

108

about 3658 individuals in impacted site of

Orogodo River, Delta State, Nigeria.

From the diversity indices of aquatic

insects in Owan River shows that the river is

not highly polluted. The Margalef’s index was

high with 4.9 in Station 3 and 6.2 in Station 1,

being the lowest and highest value respectively.

Moreover, with special reference to Margalef’s

water quality index, values greater than 3

indicate clean water conditions (Lenat et al.,

1980). The value was greater than 3 at all sites

further lending more evidence to the

“unpolluted status’’ of stations of the study

area. In other words, the stretch of Owan River

was minimally disturbed from anthropogenic

activities. The EPT richness was quite high in

all the stations sampled (24.6 – 39.2%) while

chironomids richness was between 3.8 and

20.9% with Station 3 having the lowest

chironomids richness, pointing to the fact that

Station 3 is relatively free from much human

influence. The EPT richness portrays the river

to be well oxygenated and clean as compared to

other water bodies in the Niger Delta/southern

Nigeria with low EPT richness and high

chironomids % (Arimoro and Ikomi, 2009,

Chindah et al., 1999).

In conclusion, Owan River can be said

to be slightly clean from the physicochemical

parameters data recorded and the diversity of

aquatic insects in the river. Though, effort

should be made to curb the few human

activities carried out in this river to protect the

ecosystem from further deterioration from its

present state. Indebt study on the

macroinvertebrates community structure most

especially the aquatic insects should be

embarked upon to further ascertain the general

status of the Owan River.

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Received: 02 September 2012, Accepted:20

September 2012.

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