Diversity assessment of benthic macroinvertebrate communities in Banco National Park (Banco Stream, Côte d'Ivoire)

'Diversity assessment of benthic macroinvertebratecommunities in Banco National Park (Banco Stream,Cote d’Ivoire)

Idrissa Adama Camara1*, Dramane Diomande1, Yves Kotchi Bony1,Allassane Ouattara1, Evelyne Franquet2 and Germain Gourene1

1Laboratoire d’Environnement et de Biologie Aquatique, UFR-Sciences et Gestion de l’Environnement, Universite d’Abobo-Adjame, 02 BP 801,

Abidjan 02,Ivory Coast and 2Institut Mediterraneen d’Ecologie et de Paleoecologie (IMEP), UMR CNRS 6116, Universite Paul Cezanne,

Avenue Escadrille Normandie Niemen,13397, Marseille Cedex 20, France

Abstract

In the present study, a first inventory of benthic macro-

invertebrates in the Banco Stream, Cote d’Ivoire, and the

correlations between environmental variables and taxo-

nomic richness were analysed. Seven stations were sam-

pled monthly over a 1-year period, using a hand net

(10 9 10 cm, 250 lm mesh, 50 cm length). One hun-

dred and thirty-two macroinvertebrate taxa were

recorded. These taxa were distributed among 74 families

and 15 orders belonging to Insecta (118 taxa; 89% of

total richness), Oligochaeta (seven taxa), Crustacea (five

taxa) and Mollusca (two taxa). Kruskal–Wallis test

revealed significant difference (at least P < 0.05) in

macroinvertebrate richness between upstream stations

(S1 and S2) and stations S4, S5 and S6. Chironominae

and Tanypodinae (Insecta) were the two very frequent

taxa in all the stations. Lumbriculidae (Oligochaeta), Des-

mocaris trispinosa (Crustacea) and Eurymetra sp. (Insecta)

were frequently found in the samples. Hierarchical clus-

ter analysis revealed three groups of sampling stations

according to taxonomic similarity. Taxonomic richness

was significantly and negatively correlated with conduc-

tivity, while it was significantly and positively correlated

with substrate types (woody debris and gravel). Due to

the fact that Banco stream is the locality type of an ende-

mic shrimp species (Macrobrachium thysi), this basin is of

high conservation priority.

Key words: Banco Stream, benthic macroinvertebrates,

Cote d’Ivoire, environmental variables, stream distur-

bances, taxonomic richness

Resume

Dans cette etude, nous avons realise un premier inven-

taire des macroinvertebres benthiques dans le courant

du Banco, en Cote d’Ivoire, et analyse les correlations

entre des variables environnementales et la richesse

taxonomique. Pendant un an, des prelevements furent

faits tous les mois a sept stations avec un filet manuel

(10 9 10 cm, mailles de 250 µm, 50 cm de long). On

a note la presence de 132 taxons de macroinvertebres.

Ceux-ci sont repartis parmi 74 familles et 15 ordres

appartenant aux Insectes (118 taxons, 89% de la ri-

chesse totale), Oligochetes (seven taxons), Crustaces

(five taxons) et Mollusques (two taxons). Un test de

Kruskal-Wallis a revele une difference significative (au

moins P < 0,05) de la richesse en macroinvertebres

entre les stations de l’amont (S1, S2) et les stations

S4, S5 et S6. Les Chironominae et les Tanypodinae

(Insectes) etaient les deux taxons tres frequents dans

toutes les stations. Les Lumbriculidae (Oligochetes), Des-

mocaris trispinosa (Crustacea), et Eurymetra sp. (Insec-

tes) se trouvaient souvent dans les echantillons. Une

classification hierarchique a revele trois groupes de

stations d’echantillonnage en fonction de la similarite

taxonomique. La richesse taxonomique etait significativ-

ement et inversement liee a la conductivite, alors

qu’elle etait significativement et positivement liee a cer-

tains types de substrats (debris ligneux, graviers). Etant

donne que le courant du Banco est la localite type

d’une espece de crevette endemique Macrobrachium

thysi, ce bassin est une grande priorite pour la conser-

vation.

*Correspondence: E-mail: [email protected]

© 2012 Blackwell Publishing Ltd, Afr. J. Ecol., 50, 205–217 205

Introduction

Aquatic macroinvertebrates play a major role in the

nutrients energy flux in aquatic ecosystems, constituting

the prime food source for fish (Batzer, 1998; Wong et al.,

1998) and some insectivorous birds (Ward, Holmes &

Jose, 1995). Benthic macroinvertebrates are generally

used in bioassessment programs for determining the eco-

logical quality of freshwaters (Williams & Smith, 1996;

Ogbeibu & Oribhabor, 2001; Clarke et al., 2002). In river

ecology, the benthic macroinvertebrate community is of

paramount importance for the understanding of ecosys-

tem structure and functioning (Cummins, 1992). These

organisms inhabit river, lake and reservoir bottoms, and

their distribution is directly related to food availability

and quantity, sediment type (organic, sandy, clay), sub-

strate (rock, wood and aquatic macrophytes) and water

quality (temperature, oxygen and dissolved substances)

(Callisto, 2000). However, aquatic ecosystems are under

increasing pressure from various kinds of disturbances

(Tachet et al., 2003), and both human land-use practices

and natural disturbance events can result in shifts in

benthic community composition and even ecosystem

function at the watershed scale (Allan, Erickson & Fay,

1997). Africa’s freshwater systems are being degraded at

an alarming rate despite their economic, social and eco-

logical importance (Thieme et al., 2005).

In West Africa as a whole, little is known about the

diversity of aquatic macroinvertebrates (Yameogo, Resh

& Molyneux, 2004), although several studies have been

conducted with benthic macroinvertebrate communities

in Cote d’Ivoire. These studies mainly concerned the

inventory of macroinvertebrates (Edia et al., 2007;

Diomande et al., 2009) and the relationships between

benthic macroinvertebrate communities and the environ-

mental variables (Bony et al., 2008; N’Zi et al., 2008). In

this country, available literature concerning benthic

macroinvertebrates from rivers located in conservation

areas is scarce. The benthic macroinvertebrate communi-

ties in the Banco stream basin in the Banco National

Park (BNP) are not well known. The only studies avail-

able are the description of the freshwater shrimp Macrob-

rachium thysi, which is endemic to Cote d’Ivoire (Powell,

1980), and the ecology of shrimps (Camara et al., 2009).

Of concern is the fact that Banco Stream is subjected to

anthropogenic disturbance (municipal waste waters), and

surface run-off potentially leading to its deterioration

(Camara et al., 2009).

The aims of this study were (i) to inventory the ben-

thic macroinvertebrate community along the Banco

Stream; (ii) to evaluate whether the invertebrate richness

is associated with anthropogenic disturbance; and (iii) to

investigate the relationships between macroinvertebrate

richness and environmental variables.

Material and methods

Study area and sampling stations

The Banco Stream is a short stream (about 9 km long)

located in the BNP. This park, with an area of 3000 ha,

is situated in the centre of Abidjan (economic capital)

between 5°21′–5°25′N and 4°01′–4°05′W (Fig. 1). The

climate in this park is typical of the equatorial rain for-

est, comprising four seasons (Girard, Sircoulon & Touch-

ebeuf, 1971): a great dry season (December–March), a

great rainy season (April–July), a small dry season

(August–September) and a small rainy season (October–

November). Air temperatures in the BNP average 27°C,

with an annual precipitation of approximately 1600–

2500 mm (Kouame et al., 2008).

Macroinvertebrates were sampled monthly from Octo-

ber 2006 to November 2007 at seven sampling stations:

two stations (S1 and S2) in upstream areas, three (S3,

S4 and S5) in midstream areas and the last two (S6 and

S7) in downstream areas (Fig. 1). At each station, the

length of sampled area covered ten times the channel

width (AFNOR, 1992; Lazorchak, Klemm & Peck, 1998).

Upstream stations S1 and S2 are characterized by sub-

stratum heterogeneity (mud, sand and woody debris),

with fragmented leaves. Here, the dominant macrophyte

is Thaumatococcus daniellii (Bentham, 1883) and riparian

vegetation consists of trees, mainly Turraenthus africanus,

Petersianthus macrocarpus (P. Beauv., 1968) and Dacry-

odes klaineana (Pierre). These upstream stations are not

affected by human disturbances.

Midstream station S3 receives municipal untreated

waste waters and surface run-off from Abobo city. The

substratum at S3 is mainly sandy, with a lack of aquatic

vegetation. Musanga cecropioides (Brown) and Xanthosoma

sp. are the riparian vegetations at this station. Banco

Stream is subject to organic pollution arising from efflu-

ents from a civilian prison in the midstream areas. The

effluents from this prison are regularly discharged into

the river without treatment through a tributary. Station

S4 is located on this tributary. Water is eutrophic at this

© 2012 Blackwell Publishing Ltd, Afr. J. Ecol., 50, 205–217

206 Idrissa Adama Camara et al.

station, with substantial algal growth. Station S5 is situ-

ated adjacent to stations S3 and S4 and is lined by

Indian bamboo trees (90%). Predominant substratum is

clay and silt with macrophytes being absent.

At downstream station S6, the banks are characterized

by marginal grassy vegetation [Nephrolepis biserrata

(Schott, 1834)] and a predominance of trees [Hallea

ledermannii (Krause, 1985), Alstonia boonei (De Wild,

1914)]. Predominant substrates at this station are sand

and gravel. Station S7 is the last station in the main

channel at the downstream areas. At this station, the

substratum is sandy to silty, with decaying plant matter.

Riparian vegetation consists of trees, mainly Raphia hook-

eri (Mann & Wendl, 1864) and Parkia bicolor (Chavalier,

1908). There is high vegetation coverage (80%) at this

station.

Macroinvertebrate sampling

Macroinvertebrates were sampled using a triangular hand

net (10 9 10 9 10 cm, 250 lm mesh, 50 cm length) to

obtain qualitative samples. For each sample, the net was

dragged over the river bed for a distance of 10 m, main-

taining contact with the substrate. In each month of the

sampling period, two replicate samples were collected at

each station, considering all possible microhabitats over

representative sections of the stream. The samples were

sieved in the field through a 1-mm mesh, and the mate-

rial retained on the mesh was immediately fixed in 5%

formaldehyde. In the laboratory, the samples were

washed using 1 mm sieves, then sorted and identified

using stereomicroscope (Olympus SZ 30). Macroinverte-

brates were determined to the lowest taxonomic level

Fig 1 Map of the Banco National Park

showing the sampling stations. S1–S7 =

sampling stations


Benthic macroinvertebrates in Banco Stream 207

possible (usually genus) using appropriate literature. The

keys used in this study are Monod (1980) and Powell

(1980) for the Decapoda; Brown (1994) and Bony et al.

(2008) for Mollusca; Dejoux et al. (1981) and Tachet

et al. (2003) for Insecta and Oligochaeta. The organisms

were preserved in 70% ethanol.

Environmental variables

Four environmental variables were used to describe phys-

icochemical water condition at each sampling station:

conductivity (measured in lS cm�1 with WTW-LF 340),

pH (measured with a pH meter WTW-pH 330), water

temperature (measured in °C using a thermometer built

into the pH-meter) and dissolved oxygen (measured in

mg l�1 with an oxymeter WTW DIGI 330). All these

variables were measured monthly between 7 and 12 h

in the field before macroinvertebrate sampling. The habi-

tat variables included are current velocity, water depth

and wetted channel width, canopy cover and substrate

type. Current velocity (m S�1) was measured in mid-

channel on five occasions by timing a floating object

(polystyrene cube) over five meters stretch of the river. It

was determined as the average of the five trials. Water

depth (m) and wetted channel width (m) were measured

(five transects) to the nearest centimetre inside each sta-

tion, using a decametre. Canopy cover (%) and substrate

types (mud, sand, gravel and woody debris as % of sta-

tion bottom area covered by each substrate type) were

estimated visually at each sampling station (Goldon,

McMahon & Finlayson, 1994; Arab et al., 2004).

Data analysis

Macroinvertebrate structure was described through taxo-

nomic composition, spatial and seasonal richness, and fre-

quency of occurrence (FO). FO is the percentage of samples

in which each taxon occurred. It was calculated to classify

the macroinvertebrates according to Dajoz (2000).

Before performing the comparison test, the normality

of data was checked by Kolmogorov–Smirnov test

(P > 0.05 at all stations). Differences in taxonomic rich-

ness between sampling stations and between seasons

were evaluated using the Kruskal–Wallis test, a nonpara-

metric analysis of variance, followed by the multiple

comparison ranks (Zar, 1999). Analyses were conducted

using STATISTICA 7.1 computer package. A level of

P < 0.05 was considered significant.

Because of the low seasonal variation of taxonomic

richness, outlined by the preliminary Kruskal–Wallis test,

hierarchical cluster analysis (HCA) was carried out with

the matrix of total taxa presence/absence per station to

identify grouping of sampling sites with similar macroin-

vertebrate assemblages using Euclidean distances and

Ward’s method (Edia et al., 2007; Kouakou et al., 2008).

The HCA was applied using the R package (Ihaka & Gen-

tleman, 1996). Correlations between environmental vari-

ables and taxonomic richness were tested by Spearman’s

correlation test.

Results

Environmental variables

Table 1 summarizes the mean values of environmental

variables of the Banco Stream. The highest mean value

of conductivity (163.42 lS cm�1) was observed at S4 on

the tributary. Conductivity was low in the stream chan-

nel stations and varied from 21 lS cm�1 (S1) to

40.16 lS cm�1 (S5). Temperature varied from 25.57

(S1) to 27.23°C (S4). Regarding the pH, the water of

Banco Stream was acid with low variation of pH (4.98

(S7)–6.27 (S4)). Concerning the current velocity, the

lower mean value (0.05 m S�1) was observed at S4 on

the tributary. On the stream channel, current velocity

varied from 0.12 (S7) to 0.43 m S�1 (S6). The lowest

dissolved oxygen value (1.8 mg l�1) was found in the

effluent station (S4), and the highest values were

observed in stream channel stations (�3.41 mg l�1).

Generally, water depth and width increased

from upstream to downstream stations. Depth varied from

0.17 m (S1) to 0.78 m (S7) and the width varied from

3.74 (S1) to 8.88 m (S7). At S4, the mean value of

depth and width was 0.02 and 1.21 m, respectively.

Taxonomic composition

In total, 132 macroinvertebrate taxa were recorded, dis-

tributed among 74 families and 15 orders belonging to

Insecta (118 taxa; 89% of total richness), Oligochaeta

(seven taxa), Crustacea (five taxa) and Mollusca (two

taxa) (Table 2). The cumulative numbers of taxa

recorded at upstream, midstream and downstream sta-

tions were 93, 72 and 49, respectively. Samples were

dominated by insects: Coleoptera (22%), Odonata

(20.3%), Diptera (16.9%) and Trichoptera (14%).



Ephemeroptera (11 taxa) were collected in both

upstream and downstream areas, while Plecoptera (3

taxa) were only found at the upstream stations. Eristalis

sp. (Diptera) was present only at midstream stations S3

and S4. Three species of freshwater shrimp (Decapoda)

were present: M. thysi and Macrobrachium dux (Palae-

monidae) and Desmocaris trispinosa (Desmocarididae).

All three shrimp species were absent from midstream

stations S3 and S4. Amphipoda (Gammarus pulex) and

Isopoda (Asellus aquaticus) were each represented by

only one species. Two species of Gastropod molluscs

were found in midstream at station S4 Physa marmorata

(Physidae) and Bulinus forskalii (Planorbidae). The number

of benthic taxa found only in upstream, midstream and

downstream areas were 40, 21 and 7, respectively,

while 20 taxa were present at all the sampling stations.

Spatial and seasonal pattern

The spatial distribution in macroinvertebrate richness

across sampling stations is shown in Fig. 2. The highest

richness variation was found in station S2 (7–39), S3 (8

–28) and S4 (1–24). This variation was low in station

S5 (2–11) and S6 (2–10). A Kruskal–Wallis test revealed

significant difference (at least P < 0.05) in macroinverte-

brate richness between upstream stations (S1 and S2)

and midstream and downstream stations S4, S5 and S6.

High values for taxonomic richness were obtained in

the dry season months for stations S1 (15), S2 (23), S3

(17) and S6 (8), while in stations S4 (24), S5 (9) and S7

(12), the highest values were registered in the rainy sea-

son. The taxonomic richness of all sampling stations was

not significantly different between seasons (Kruskal–Wal-

lis test; P > 0.05).

Frequency of occurrence (FO)

Chironominae and Tanypodinae (Insecta) were the two

commonest taxa (FO > 50%) found at all the sampling

stations (S1 and S7). Lumbriculidae (Oligochaeta), D.

trispinosa (Crustacea) and Eurymetra sp. (Insecta) were

frequently (25% < FO < 50%) found in the majority of

sample stations. In the upstream stations (S1; S2), five

taxa (Neurogomphus sp., Rhagadotarsus caprivia hutchinsoni,

Limnius sp., Dipseudopsis capensis and Ceratopogon sp.)

were very frequent, and 14 taxa were frequent. Tubifici-

dae, P. marmorata, Orthetrum sp. and Tipula sp. were the

four very frequent taxa in the midstream area, with 17

frequent taxa. Downstream stations registered three very

frequent taxa (Erythromma sp, Orthetrum sp. and Simuli-

um sp.) and six frequent taxa.

Cluster and correlation between environmental variables and

taxonomic richness

Hierarchical cluster analysis used to evaluate the faunal

similarities between study stations showed three groups

(Fig. 3). Cluster I was composed of the upstream (S1 and

S2) and downstream (S6, S7) stations. Samples from sta-

tion S4 composed cluster II, while midstream stations S3

and S5 formed cluster III. Overall benthic macroinverte-

brate richness was significantly different between

clusters, being significantly higher in cluster I (Kruskal–

Wallis test, P < 0.05).

The Spearman’s correlation analysis indicated that

macroinvertebrate richness was significantly and

negatively correlated with conductivity, while it was

significantly and positively correlated with gravel and

woody debris (Table 3).

Table 1 Average values of physico-chemical parameters of studied stations in Banco Stream (mean and standard deviation)

Station N

Conductivity

(lS cm�1)

Water temperature

(°C) pH

Dissolved

oxygen

(mg l�1)

Current

(m S�1)

Water depth

(m)

Wetted

channel

width (m)

S1 12 21 ± 0.93 25.57 ± 0.37 5.14 ± 0.9 5.63 ± 0.43 0.36 ± 0.12 0.17 ± 0.03 3.74 ± 0.8

S2 12 24.78 ± 6.3 26.18 ± 1.38 5.2 ± 0.86 4.33 ± 2.08 0.32 ± 0.18 0.31–0.05 3.42 ± 0.65

S3 12 35.75 ± 2.16 26.28 ± 1.04 5.56 ± 10.03 4.42 ± 2.5 0.37 ± 0.2 0.33 ± 0.08 4 ± 0.61

S4 12 163.42 ± 5.78 27.23 ± 0.81 6.27 ± 0.41 1.8 ± 1.17 0.05 ± 0.05 0.02 ± 0.01 1.21 ± 0.07

S5 12 40.16 ± 15.3 26.07 ± 1.12 5.59 ± 1.11 4.71 ± 1.7 0.33 ± 0.19 0.50 ± 0.2 7.2 ± 0.5

S6 12 29.5 ± 14.6 26.28–0.9 5.08 ± 0.64 5.41 ± 0.22 0.43 ± 0.15 0.53 ± 0.14 4.88 ± 0.54

S7 12 40.09 ± 9.9 26.11 ± 1.06 4.98 ± 0.56 3.41 ± 0.82 0.12 ± 0.07 0.78 ± 0.23 8.88 ± 0.67



Table

2Therecorded

taxaofben

thic

macroinvertebratesattheseven

samplingstationsin

Banco

Stream

Class

&order

Family

Taxon

Stations

S1

S2

S3

S4

S5

S6

S7

Oligoch

aeta

Haplotaxina

HaplotaxidaeHoffmeister,1843

Branchiodriluscleistochaeta

Dahl,1957

**

Lumbricina

Lumbricidae

**

Lumbricu

lidae

****

***

***

**

Tubificina

NaididaeEhrenberg,1828

**

*** **

TubificidaeVejdovsky,1876

***

***

***

Proppapidae

***

Mollusca

Gasteropoda

Physidae

Physa

marmorataGuilding,1828

****

Planorbidae

Bulinusforskalii(Ehrenberg,1831)

**

Crustacea

Amphipoda

Gammaridae

Gam

maruspulex(Lim

naeu

s,1758)

**

Decapoda

Desmocarididae

Desmocaristrispinosa(A

urivillius,1898)

***

***

*****

***

Palaem

onidae

Macrobrachium

thysi(Powell,1980)

****

*

Macrobrachium

dux(Len

z,1910)

***

Isopoda

Aselidae

Asellusaquaticus(Lim

naeu

s,1758)

**

Insecta

Ephem

eroptera

AmeletidaeEaton,1885

*

Baetidae

Centroptilum

Eaton,1881

**

CloeonLeach

,1815

****

***

Pseudocentroptilum

Bogoescu

,1947

*

Caen

idae

CaenisStephen

s,1835

*

Caenodes

Ulm

er,1924

*

Caenom

edea

Thew

,1960

*

Ephem

erellidae

Ephem

erella

Walsh,1863

*

Leptophlebiidae

Adenophlebiodes

Ulm

er,1924

***

*

Tricorythidae

MachadorythusDem

oulin,1959

*

DicercomyzonDem

oulin,1954

**

Plecoptera

Perlidae

DinocrasKlapalek,1907

*

Martham

eaKlapalek,1907

*

Neoperlaspio

(New

man,AE,1839)

*

Odonata

Calopterygididae

CalopteryxLeach

,1815

***

PhaoniridipennisBurm

eister,1839

*

Coen

agrionidae

Enallagm

aSelys,1875

**

ErythrommaHansemann,1823

****

**

PseudagrionFraser,1956

**

**



Table

2(Continued)

Class

&order

Family

Taxon

Stations

S1

S2

S3

S4

S5

S6

S7

Corduliidae

CorduliaLeach

,1815

**

Oxygastra

curtisii(Dale,1834)

*

Macromiidae

Phyllom

acromia

Selys,1878

**

**

Gomphidae

Gom

phidia

Selys,1854

**

Gom

phusLeach

,1815

**

*

Lestinogom

phusMartin,1912

**

NeurogomphusKarsh,1890

***

***

*

OphiogomphusSelys,1854

*

Phyllogom

phusaethiops

Selys,1854

****

**

**

LestidaeCalvert,1901

**

Insecta

Odonata

Libellulidae

Brachythem

isBrauer,1868

**

Bradinopyga

strachani(Kirby,1900)

**

*

LeucorrhinisBrittinger,1850

*

Libellula

Lim

naeu

s,1758

**

**

Orthetrum

Selys,1848

****

**

***

Palpopleura

lucialucia(Drury,1773)

**

Pantala

flavescens(Fabricius,1798)

*

Urothem

isBrauer,1868

*

Zygonyxtorridus(Kirby,1889)

**

**

*

Heteroptera

Corixidae

Micronecta

Kirkadly,1897

*

Belostomidae

DiplonychusLaporte,

1833

****

*

Gerridae

Rhagadotarsuscaprivia

hutchinsoniChina,1931

***

*

Eurymetra

Esaki,1926

***

***

***

**

GerrisFabricius,1794

**

Hydrometridae

Hydrom

etra

stagnorum

(Lim

naeu

s,1758)

*

Mesoveliidae

Mesovelia

Mulsant&Rey,1852

*

Naucoridae

Naucoriscimicoides(Lim

naeu

s,1758)

***

Nepidae

Neparubra(Lim

naeu

s,1758)

**

*

Notonectidae

AnisopsSpinola,1837

*

Enithares

Spinola,1837

*

Notonecta

glauca

(Lim

naeu

s,1758)

*

Pleidae

PleaLeach

,1817

**

Ranatridae

Ranatra

linearis(Lim

naeu

s,1758)

***

Veliidae

MicroveliaWestw

ood,1834

**



Table

2(Continued)

Class

&order

Family

Taxon

Stations

S1

S2

S3

S4

S5

S6

S7

Lepidoptera

**

**

PyralidaeLatreille,

1802

***

*

Coleoptera

Dryopidae

DryopsOlivier,1791

*

Pom

atinusSturm

,1853

*

Dytiscidae

ColymbetesClairville,1806

**

Dytiscusmarginalis(Lim

naeu

s,1758)

*

HydaticusflavolineatusBohem

an,1848

*

PlatambusThomson,1859

*

Elm

idae

Elm

isLatreille,

1802

*

Lim

niusIlliger,1802

***

*

OulimniusGozis,1886

**

Potam

odytesZim

mermann,1919

**

RiolusMulsant&Rey,1872

**

Eubriidae

Eubrinax

Lacordaire,

1857

*

Gyrinidae

GyrinusMiiller,1764

**

*

OrectochilusDejean,1833

***

AulonogyrusRegim

bart,1883

*

Haliplidae

PeltodytesRegim

bart,1878

**

*

Hydrophilidae

Amphiops

Ereichson,1843

**

EnochrusThomson,1859

***

***

HydrobiusLeach

,1815

**

*

Insecta

Coleoptera

Hydrophilidae

HydrocharaBerthold,1827

**

HydrophilusGeaffroy,1762

**

Noteridae

NoterusClairville,1806

*

Scirtidae

Cyphon

Paykull,1799

***

**

Hydrocyphon

Redtenbach

er,1858

***

Microcara

Thomson,1859

*

Scirtes

Illiger,1807

***

*

Trich

optera

BeraeidaeWallen

gren,1891

*

Ecn

omidae

Ecnom

usMcLach

lan,1864

*

Hydropsych

idae

CheumatopsycheWallen

gren,1891

****

**

DiplectronaWestw

ood,1840

*

HydropsychePictet,1834

**

Protomacronem

aUlm

er,1904

**

PolymorphanisusWalker,1852

**



Table

2(Continued)

Class

&order

Family

Taxon

Stations

S1

S2

S3

S4

S5

S6

S7

Lepidostomatidae

Lepidostomahirtum

(Fabricius,1775)

*

Leptoceridae

OecetisMcLach

lan,1877

**

Parasetodes

McLach

lan,1880

**

Philopotamidae

Chim

arra

Stephen

s,1829

**

*

Philopotam

usStephen

s,1829

**

Polycentropodidae

DipseudopsiscapensisWalker,1852

***

****

Plectrocnem

iaStephen

s,1836

**

Rhyacophilidae

RhyacophilaPictet,1834

*

SeriocostomatidaeStephen

s,1836

*

Diptera

Athericidae

AtheryxMeigen

,1803

*

AtrichopscrassipesMeigen

,1820

***

Ceratopogonidae

Ceratopogon

Meigen

,1803

*****

**

*

DasyheleinaeKieffer,1911

**

***

ChironomidaeNew

man,1834

Chironominae

***

***

***

*****

***

***

Orthocladiinae

**

Tanypodinae

***

***

****

***

***

***

Culicidae

CulexLim

naeu

s,1758

**

Dixidae

DixaMeigen

,1818

*

Dolich

opodidaeLatreille,

1809

**

Empididae

ClinocerinaeMeigen

,1800

***

**

Lim

oniidae

Pilaria

Sintenis,1889

***

**

Psych

odidaeNew

man,1834

***

Ptych

opteridae

Ptychoptera

Meigen

,1803

*

Scatophagidae

Acanthocnem

aBecker,1894

***

Sim

uliidae

Sim

ulium

Latreille,

1802

**

*****

StratiomyidaeLatreille,

1802

*

Syrphidae

EristalisLatreille,

1804

***

Tabanidae

TabanusLim

naeu

s,1758

***

Tipulidae

Tipula

Lim

naeu

s,1758

***

***

***

*

73

33

87

46

30

33

24

35

Upstream

Midstream

Downstream

93

72

49

Veryfrequen

t(FO

>50%),

**frequen

t(25%

�FO

�50%),

*rare

occurren

ce(FO

<25%).



Discussion

The number of benthic macroinvertebrates taxa collected

in the study (132) is high when compared with earlier

studies in other Ivorian rivers. Diomande et al. (2009)

used Ekman samples to collect 50 taxa in the Agneby

River and Dietoa (2002) collected 69 taxa with a drift

net from the same river. This difference in taxonomic

richness between studies can probably be explained by

the sampling methods used and the types of habitats

sampled. The Banco Stream is also rich when compared

with other African freshwater bodies (Durand & Leveque,

1981; Dejoux, Lauzanne & Leveque, 1969). The richness

found in the Banco Stream macroinvertebrate assem-

blage is, in fact, more similar to those reported for south-

eastern Cote d’Ivoire (Edia et al., 2007), using the same

sampling methods.

The two molluscs (P. marmorata and B. forskalii) sam-

pled in this study occurred only in station S4 (mid-

stream). However, previous studies (Binder, 1957; Bony

et al., 2008) found no benthic molluscs in the Banco

Stream, making this the first recorded occurrence of this

benthic community in the BNP. The probable reason for

the presence of these gastropods is organic material from

the civilian prison effluent at this station. The input of

organic matter into rivers modifies the bottom substrate

characteristics, leading to increased alga production. Roy

et al. (2003) and Brabec et al. (2004) pointed out that it

is the influx of organic matter and the subsequent nutri-

ent transformation processes which explain low organic

pollution and stream eutrophication impact stream ben-

thic fauna. Most pulmonate snails are commonly known

as sewage snails and are associated with polluted water

(Brown, 1994). This could account for their absence in

relatively less-disturbed habitats and their slow progress

in invading bodies of water where the impact of human

activities is relatively small (Dirk et al., 2008). Ndifon &

Ukoli (1989) confirmed that the pulmonate snails Physa

and Bulinus were mainly encountered in bodies of water

polluted by high quantities of human and animal excre-

ment, as well as by domestic sewage.

The number of shrimp species (3) found in the Banco

Stream is low when compared with other Ivorian rivers:

nine species are found in Boubo River (N’Zi et al., 2008)

and ten species are found in the Me River (N’Zi et al.,

2003). These differences are probably due to the size of

these three rivers: the Banco stream is small (9 km long,

4.5 m wide), and the Boubo River (130 km long,

13.5 m wide) and Me River (140 km long, 13.5 m wide)

(N’Zi et al., 2003; N’Zi et al., 2008) are long. The

absence of shrimps at midstream stations S3 and S4 can

be explained by the fact that pollutants are regularly dis-

charged into the stream in the form nontreated domestic

sewage at these locations, causing water quality deterio-

ration.

All the Plecoptera and most of the Ephemeroptera,

Coleoptera and Trichoptera were collected from upstream

stations. These taxa require good water quality and their

absence in the midstream areas suggest that these organ-

isms cannot tolerate the water in this part of the Banco

Stream that also has few suitable habitats. Edia et al.

(2007) found a wide distribution of Ephemeroptera and

Plecoptera in other Cote d’Ivoire localities that have high

substrate heterogeneity.

Ceratopogon sp. (Ceratopogonidae) was mainly found at

upstream station S2 of the Banco Stream among macro-

phytes and riparian vegetation, which is similar to the

finding of Ogbeibu & Oribhabor (2001) in the Ikpoba

River in Nigeria. Eristalis sp. (Syrphidae) was recorded in

shallow waters in stations S3 and S4 in the Banco

Stream, and has also been found in sewage-polluted riv-

ers (Ravera, 2001; Rueda et al., 2002). Their ability to

survive is the result of using their retractile anal respira-

tory siphons, and the presence of decaying organic mat-

ter, which they feed on (Pennak, 1978; Tachet et al.,

2003). Freshwater crabs are absent from our samples.

According Colpo, Ribeiro & Santos (2005), freshwater

crabs are usually abundant in streams, rivers and lakes.

Their absence in our samples is probably due to our sam-

pling methods.

High values for taxonomic richness were obtained

during the dry season in Goias State, Brazil, in a study

of the spatial–temporal distribution of benthic macroin-

vertebrate communities in streams in Goiania Ecological

Park (Bispo & Oliveira,1998) where the main environ-

mental factors that influenced the pattern and macroin-

vertebrate richness were conductivity and substrate

types (woody debris, gravel). Sampling stations S1, S2,

S6 and S7 of the Banco Stream, placed in cluster I are

less severely impacted by human activities and were

sufficiently stable to maintain good use of their

resources by natural biota (Barbosa et al., 1997),

explaining the comparatively great taxonomic richness

found. In addition, the upstream and downstream

sediments are composed of several fractions, increasing



habitat diversity and the likelihood of colonization by

benthic macroinvertebrates, as observed by Cota et al.

(2002) in a study of the water quality of the Doce

River. Taxonomic richness is generally acknowledged to

be dependent on habitat heterogeneity (Eggleston, Ethe-

rington & Elis, 1998). Sampling stations S4 (cluster II),

S3 and S5 (cluster III) showed low taxonomic richness.

These stations are affected by human activities, includ-

ing municipal waste waters and surface run-off from

the neighbouring cities.

This study identifies for the first time a wide range of

benthic macroinvertebrates in the Banco Stream and

identifies differences in taxonomic richness between areas

affected to some degree by more human activities. Our

results point to the need to prioritize conservation actions

for the middle Banco Stream especially because Banco

Stream is the locality type of an endemic shrimp species

(M. thysi). The effects of the civilian prison and other

domestic waste discharges that are revealed can be miti-

gated, if this waste is properly channelled and treated

before discharge into the water surface in the BNP.

Acknowledgements

The authors are extremely grateful to the ‘Office Ivoiri-

enne des Parcs et Reserves’ and the ‘Direction des eaux

et Forets de Cote d’Ivoire’ for permitting access to the

Banco National Park. We are grateful to Marjorie

SWEETKO and Dr. Mexmin KONAN for their help and

improving the English in the manuscript.

References

AFNOR. (1992) Qualite de l’eau, Recueil des Normes Francaises,

1994. Essai des eaux. Determination de l’indice biologique

global normalise (IBGN). NF T 90-3. 684–692.

Allan, J.D., Erickson, D.L. & Fay, J. (1997) The influence of

catchment land use on stream integrity across multiple spatial

scales. Freshw. Biol. 37, 149–161.

Arab, A., Lek, K., Lounaci, A. & Park, Y.S. (2004) Spatial and

temporal patterns of benthic invertebrate communities in an

intermittent river (North Africa). Ann. Limnol.-Int. J. Lim. 40,

317–327.

Barbosa, F.A.R., Souza, E.M.M., Vieira, F., Renault, G.P.C.P.,

Rocha, L.A., Maia-Barbosa, P.M., Oberda, S.M. & Mingoti, S.A.

Table 3 Spearman’s correlation of macroinvertebrate richness

and physico-chemical data of Banco Stream

Environmental variables n r P

Conductivity 12 �0.5 *

Temperature 12 �0.21 ns

pH 12 �0.18 ns

Dissolved oxygen 12 0.08 ns

Canopy 12 0.14 ns

Current velocity 12 0.04 ns

Depth 12 �0.09 ns

Width 12 �0.21 ns

Mud 12 �0.25 ns

Sand 12 0.19 ns

Gravel 12 0.5 *

Woody debris 12 0.63 *

r, Spearman’s correlation coefficient; ns, nonsignificant relation-

ship.

*Indicates significant difference (P � 0.05).

Fig 2 Box plots of macroinvertebrate richness in Banco Stream at

sampling stations: S1–S7 = different letters denote significant dif-

ferences between sampling stations (P < 0.05; Kruskal–Wallis test)

Fig 3 Hierarchical cluster analysis dendogram showing similari-

ties in benthic macroinvertebrate assemblages between sampling

stations using taxon presence/absence: S1–S7 = sampling sta-

tions



(1997) Impactos antropicos e biodiversidade aquatica. In:

Biodiversidade, populacao e economia: uma regiao de Mata

Atlantica (Ed. J.A. De Paulo). UFMG/CEDEPLAR, Belo

Horizonte.

Batzer, D.P. (1998) Trophic interactions among detritus,

benthic midges, and predatory fish in a freshwater marsh.

Ecology 79, 1688–1698.

Binder, E. (1957) Mollusques aquatiques de Cote d’Ivoire:

Gasteropodes. Bulletin de l’IFAN 19, 97–125.

Bispo, P.C. & Oliveira, G.L. (1998) Distribuicao espacial de

insetos aquaticos (Ephemeroptera, Plecoptera e Trichoptera)

em corregos de Cerrado do Parque Ecologico de Goiania,

Estado de Goias. Oecologia Brasiliensis 5, 19–33.

Bony, Y.K., Kouassi, N.C., Diomande, D., Gourene, G., Verdoit-

Jarraya, M. & Pointier, J.P. (2008) Ecological conditions for

the spread of the invasive snail Physa marmorata (Pulmonata:

Physidae) in Ivory Coast. Afr. Zool. 43, 53–60.

Brabec, K., Zahradkova, S., Nemejcova, D., Paril, P., Kokes, J. &

Jarkovsky, J. (2004) Assessment of organic pollution effect

considering differnces between lotic and lentic stream habitats.

Hydrobiologia 516, 331–346.

Brown, D.S. (1994) Freshwater Snails of Africa and their

Medical Importance. Taylor & Francis, London.

Callisto, M. (2000) Macroinvertebrados bentonicos. In: Impacto

e recuperacao de um ecosistema amazonico (Eds R.L. Bozelli,

F.A. Esteves and F. Roland). Edition UFRJ, Rio de Janeiro.

Camara, A.I., Konan, K.M., Diomande, D., Edia, O.E. & Gourene,

G. (2009) Ecology and diversity of freshwater shrimps in

Banco National Park, Cote d’Ivoire (Banco River Basin).

Knowl. Manag. Aquat. Ec. 393, 1–10.

Clarke, R.T., Furse, M.T., Gunn, R.J.M., Winder, J.M. & Wright,

J.F. (2002) Sampling variation in macroinvertebrate data and

implications for river quality indices. Freshw. Biol. 47, 1735–

1751.

Colpo, K.D., Ribeiro, O. & Santos, S. (2005) Population biology

of the freshwater anomuran Aegla longirostri (Aeglidea) from

south Brazilian streams. J. Crust. Biol. 25, 495–499.

Cota, L., Goulart, M., Moreno, P. & Callisto, M. (2002) Rapid

assessment of river water quality using an adapted BMWP

index: a practical tool to evaluate ecosystem health. Verh. Int.

Verein. Limnol. 28, 1–4.

Cummins, K.W. (1992) Invertebrates. In: The Rivers Handbook –

Hydrobiologia and Ecological Principles, Vol 2 (Eds P. Calow

and G.E. Petts). Blackwell Science Ltd., Oxford.

Dajoz, R. (2000) Precis d’Ecologie,7eme edn. Dunod, Paris.

Dejoux, C., Lauzanne, L. & Leveque, C. (1969) Evolution

qualitative et quantitative de la faune benthique dans la

partie est du lac Tchad. Cahier de l’ORSTOM, serie Hydrobilogie

2, 51–78.

Dejoux, C., Elouard, J.M., Forge, P. & Maslin, J.L. (1981)

Catalogue iconographique des insectes aquatiques de Ivory

Coast. Report ORSTOM, Bouake, Ivory Coast.

Dietoa, Y.M. (2002) Entomofaune et strategies alimentaires des

poissons du genre Brycinus (Characidae) en milieux fluviatiles

et lacustre (Bassins Bia et Agneby; Ivory Coast). These de

Doctorat. Universite d’Abobo-Adjame, Abidjan.

Diomande, D., Bony, K.Y., Edia, O.E., Konan, F.K. & Gourene, G.

(2009) Diversite des macroinvertebres benthiques de la riviere

Agneby (Cote d’Ivoire; Afrique de l’Ouest). Eur. J. Sci. Res 35,

368–377.

Dirk, J.R., Jeanne, L.N., Peter, J.A., Andrew, R.D., Ferdinand, C.

M., Devlyn, H., Cornelius, J.K., Gillian, A.M., Juanita, M. &

Robert, J.S. (2008) Designing protected areas to conserve

riverine biodiversity: lessons from a hypothetical redesign of

the Kruger National Park. Biol. Conserv. 141, 100–117.

Durand, J.R. & Leveque, C. (1981) Flore et faune Aquatiques de

l’Afrique Sahelo-Soudanienne (Tome II). ORSTOM, Paris, France.

p. 483.

Edia, O.E., Brosse, S., Ouattara, A., Gourene, G., Winterton, P.

& Lek-Ang, S. (2007) Aquatic insect assemblage patterns

in four West-African coastal rivers. J. Biol. Sci. 7, 1130–

1138.

Eggleston, D., Etherington, L. & Elis, W. (1998) Organism

response to habitat patchiness: species and habitat-dependent

recruitment of decapod crustaceans. J. Exp. Mar. Biol. Ecol.

223, 111–132.

Girard, G., Sircoulon, J. & Touchebeuf, P. (1971) Apercu sur les

regimes hydrologiques. In: Milieu naturel de la Cote d’Ivoire,

Vol 50 (Eds J.M. Avenard, M. Eldin, J.L. Guillaumet, E.

Adjanohoun and A. Perraud). Memoire ORSTOM, Paris,

France, 50, 109–155.

Goldon, N.D., McMahon, T.A. & Finlayson, B.L. (1994) Stream

Hydrology, an Introduction for Ecologists. Wiley & Sons, New

York, NY.

Ihaka, R. & Gentleman, R. (1996) R: a language for data

analysis and graphics. J. Comput. Graph. Stat. 5, 299–314.

Kouakou, A.K., Stanislas, S.Y., Gouli, G.B., Essetchi, P.K.,

N’Douba, V. & Kouassi, J.N. (2008) Influential environmental

gradients and patterns of fish assemblages in a West African

basin. Hydrobiologia 603, 159–169.

Kouame, N.G., Tohe, B., Assemian, N.E., Gourene, G. & Rodel, M.

O. (2008) Prey composition of two syntopic Phrynobatrachus

species in the swamp forest of Banco National Park, Ivory

Coast. Salamandra 3, 177–186.

Lazorchak, J.M., Klemm, D.J. & Peck, D.V. (1998) Environmental

Monitoring and Assessment Program- Surface Water: Field

Operations and Methods for Measuring the Ecological

Condition of Wadeable Streams. U.S. Environmental

Protection Agency, Washington, DC, EPA/620/R-94/004F.

Monod, T. (1980) Decapode. In: Flore et faune aquatiques de

l’Afrique sahelo-soudanienne, Vol 44 (Eds J.R. Durand and C.

Leveque). ORSTOM, Paris, Tome I.

Ndifon, G.T. & Ukoli, F.M.A. (1989) Ecology of freshwater snails

in south-western Nigeria. I: Distribution and habitat

preferences. Hydrobiologia 171, 231–253.

N’Zi, K.G., Goore Bi, G., N’Douba, V., Kone, T., Kouamelan, E.P.

& Ollevier, F. (2003) Diversite biologique des crevettes d’un

petit bassin cotier ouest africain, riviere Me, Cote d’Ivoire en



relation avec les variables environnementales. Sciences

naturelles et agronomie 27, 17–27.

N’Zi, K.G., Goore Bi, G., Kouamelan, E.P., Kone, T., N’Douba, V.

& Ollevier, F. (2008) Influence des facteurs

environnementaux sur la repartition spatiale des crevettes

dans un petit bassin ouest africain – riviere Boubo – Cote

d’Ivoire. Tropicultura 26, 17–23.

Ogbeibu, E.A. & Oribhabor, J.B. (2001) Ecological impact of river

impoundment using benthic macroinvertebrates as indicators.

Water Res. 36, 2427–2436.

Pennak, R.W. (1978) Freshwater invertebrates of the United

States. John Wiley, New York, NY.

Powell, C.B. (1980) The genus Macrobrachium in West Africa; I:

Macrobrachium thysi, a new large-egged species from the Cote

d’Ivoire (Crustacea Decapoda Palaemonidae). Rev. Zool. Afr.

94, 317–326.

Ravera, O. (2001) A comparison between diversity, similarity

and biotic indices applied to the macroinvertebrate

community of a small stream: the Ravera river (Como

Province, Northern Italy). Aquat. Ecol. 33, 97–107.

Roy, A.H., Rosemond, A.D., Paul, M.J. & Wallace, J.B. (2003)

Stream macroinvertebrate response to catchment urbanization

(Georgia, U.S.A.). Freshw. Biol. 48, 329–346.

Rueda, J., Camacho, A., Mezquita, F., Hernandez, R. & Roca, J.R.

(2002) Effect of episodic and regular sewage discharges in the

water chemistry and macroinvertebrate fauna of a

Mediterranean stream. Water Air Soil Pollut. 140, 425–444.

Tachet, H., Richoux, P., Bourneau, M. & Usseglio-Polatera, P.

(2003) Invertebres d’eau douce; systematique, biologie,

ecologie. CNRS Editions, Paris.

Thieme, M., Abell, R., Stiassny, J.L.M., Skelton, P., Lehner, B.,

Teugels, G.G., Dinerstein, E., Kamdem Toham, A., Burgess, N. &

Olson, D. (2005) Freshwater Ecoregions of Africa and

Madagascar: A Conservation Assessment. Island Press,

Washington, DC, USA.

Ward, D., Holmes, N. & Jose, P. (1995) The New River and

Wildlife Handbook. RSPP, NRA, The Wildlife Trusys,

Bedfordshire.

Williams, D.D. & Smith, M.R. (1996) Colonization dynamics of

river benthos in response to local changes in bed

characteristics. Freshw. Biol. 36, 237–248.

Wong, A.H.K., Williams, D.D., McQueen, D.J., Demers, E. &

Ramcharan, C.W. (1998) Macroinvertebrates abundance in

two lakes with contrasting fish communities. Arch. Hydrobiol.

141, 283–302.

Yameogo, L., Resh, V.H. & Molyneux, D.H. (2004) Control of

rivers blindness in West Africa: case history of biodiversity in

a disease control program. EcoHealth 1, 172–183.

Zar, J.H. (1999) Biostatistical Analysis, 4th edn. Prentice-Hall,

Englewood Cliffs, New Jersey.

(Manuscript accepted 04 December 2011)

doi: 10.1111/j.1365-2028.2011.01312.x



Documents

Diversity assessment of benthic macroinvertebrate communities in Banco National Park (Banco Stream, Côte d'Ivoire)