International Journal of Fisheries and Aquatic Sciences 2(2): 29-37, 2013
ISSN: 2049-8411; e-ISSN: 2049-842X
© Maxwell Scientific Organization, 2013
Submitted: January 05, 2013
Accepted: January 31, 2013
Published: May 20, 2013
Dynamics of Zooplankton of Azuabie Creek in the Upper Bonny Estuary of the Niger Delta
Calista A. Miebaka and Erema R. Daka
Department of Applied and Environmental Biology, Rivers State University of Science and Technology,
Port Harcourt, Nigeria
Abstract: The dynamics of zooplankton community of Azuabie Creek in the Upper Bonny Estuary of the Niger
Delta was studied over a one-year period from April 2006 to March 2007. Ten sites which included locations with
sources of human and industrial pollutant inputs and relatively uncontaminated control points along the creek were
chosen for the study. Water and plankton samples were collected monthly from each station using standard methods,
followed by laboratory analyses. A total of 35 species of zooplankton belonging to eight major taxonomical groups
were recorded during the study periods. Out of the total number, 20 species representing 57.14% belonged to the
class copepoda; 2 species (5.71%) represented the class euphausiaceae; 1 species (2.86%) represented class
spionidae; 2 species (5.71%) belonged to the class protozoa; 4 species (11.43%) belonged to the class cladocera; 3
species (8.57%) belonged to the class insecta, 2 species (5.71%) belonged to cumaceane while 1 species (2.86%)
represented the class nematoda. In terms of abundance, the highest number of occurrence found was the class
copepoda (88.95%), followed by cumacean (2.76%); cladocera (2.35%), protozoa (1.99%), spionidae (1.63%),
insecta (1.28%); nematoda (0.76%) and euphausiid (0.26%). There were significant spatial and monthly (seasonal)
differences (p<0.001), as well as interactions in the abundance of major zooplankton taxa. Community indices had
significant differences between sampling locations and months, with the wet season months generally having higher
species richness, diversity and evenness but lower dominance.
Keywords: Abundance, Bonny Estuary, diversity, dominance, Nigeria, plankton
condition. Therefore, an expression of the nature and
health of the aquatic communities is an expression of
the quality of the water. The plankton of the Upper
Bonny Estuary have been the focus of studies by
different authors (Chindah, 2003; Chindah and Pudo,
1991; Ogamba et al., 2005; Ekeh, 2005) but none of
these covers the Azuabie creek. The Azuabie creek is
located between latitude 7°3’ N, longitude 4°48’ E and
latitude 7°1’ 30” N and longitude 4°52” in the upper
Bonny Estuary, Southern Nigeria. The dominant
vegetation along the banks of the creek are Nypa palm,
Rhizophora sp, Avicinia sp and some water ferns.
Azuabie village is a settlements along the river bank.
The major abattoir in the city of Port Harcour, Nigeria,
is located by the bank of the creek; major production
industries are also located by the bank of the creek and
the effluents from a vegetable oil factory drain into the
creek via a creeklet. This study therefore focused on the
spatial and seasonal dynamics of the zooplankton
community of Azuabie creek over a full year.
INTRODUCTION
The economic development of many coastal
regions depends on the quality and capacity of their
water ways (Cruz-Motta and Collins, 2004). Owing to
this, the ecological study of the Bonny Estuarine
System due to increasing urbanization and
industrialization is very vital. The Bonny Estuary is one
of the richest estuaries in the Niger Delta aquatic
ecosystem, with a network of creeks/tributaries linking
various habitats of highly economic and ecological
importance. The estuary is open with abundant
composition of flora and fauna of unique biodiversity.
The system is vulnerable to pollution by organic,
industrial and chemical pollutants/wastes from several
industries and human habitats located by the banks and
water fronts and has been the subject of much research
over the last two decades (Chindah et al., 1993;
Ekweozor et al., 2004; Daka and Abby-Kalio, 1997;
Inyang et al., 2006; Ekeh, 2005, Ikomah et al., 2005;
Molson et al., 2005; Daka et al., 2007).
Plankton constitutes the primary producers of the
aquatic food chain. Any variation in the water quality
affects their abundance, species composition and
diversity, stability, productivity and physiological
MATERIALS AND METHODS
Study sites: Ten sampling stations were located along
the Azuabie Creek, to cover of land-based sources of
Corresponding Author: Erema R. Daka, Department of Applied and Environmental Biology, Rivers State University of
Science and Technology, Port Harcourt, Nigeria, Tel.: +234(0)8033385665
29
Int. J. Fish. Aquat. Sci., 2(2): 29-37, 2013
Fig. 1: Azuabie Creek showing locations of sampling stations. Inset -The Niger Delta showing location of the creek
contaminant inputs into the creek as well as presumably
uncontaminated locations (Fig. 1). The sampling
stations and their geographical coordinates of these
stations are as follows: Stations 1 (4°48'08.871"N,
7°04'15.763") and 2 (4°48'19.958"N, 7°03'46.932"E)
were relatively away from any visible anthropogenic
influence
but
stations
3
(4°48'28.591"N,
7°03'29.218"E), 4 (4°48'12.462"N, 7°03'16.906"E) and
5 (4°48'18.675"N, 7°03'25.946"E) were located along
the creeklet that receives industrial effluents from
Trans-Amadi Industrial drains in addition to a waste
dump site that is close to station 3. Stations 6
(4°48'40.150"N, 7°03'28.370"E) and 7 (4°48'48.411"N,
7°03'30.411"E) were close to a domestic waste
dumpsite and a pier latrine. Station 8 (4°48'52.041"N,
7°02'49.661"E) was close to a major abattoir and some
industries
while
stations
9
(4°49'09.796"N,
7°02'50.446"E) and 10 (4°49'26.711"N, 7°02'44.237")
were also close to domestic waste inputs upstream of
the creek.
Sample collection and analyses: The sampling was
done monthly for one year (April 2006 to March 2007)
to determine spatial and temporal dynamics. In situ
measurements were taken for fast-changing surface
water parameters such as temperature, dissolved
oxygen, total dissolved solids and conductivity. Water
samples were also collected in appropriate containers
30
Int. J. Fish. Aquat. Sci., 2(2): 29-37, 2013
and transported to the laboratory for analysis using
standard methods. Zooplankton was collected by
sieving fifty liters of water through plankton net of
mesh size 45µm, after which the filtrate was transferred
into a one liter open mouthed plastic container, fixed
with 5% formalin and then taken to the laboratory for
identification. At each station, five replicates were
collected.
The zooplankton samples were kept to stand for a
minimum of 24 h in the laboratory and supernatant
decanted until a 50ml concentrated sample was
achieved. The concentrated sample was mixed carefully
by shaking and 1mL of the sub-sample was taken and
transferred into a Bogorov counting chamber using a
stampel pipette. Before enumeration and identification
of the organisms under a binocular compound
microscope with modifications of 40x and 100x, few
drops of laboratory prepared lugols iodine were added
for staining to aid the viewing process. Five replicates
of the samples were analysed for each station. Results
were expressed as number of organisms per mL.
Identification plates from Barnes (1980), Durand and
Lévesque (1980) and Newell and Newell (1963) were
used as guides for the zooplankton identification.
10
80
70
60
50
40
30
20
10
0
8
6
4
2
st10
st9
st8
st7
st6
stations
stations
A: Copepod
B: Spionid
station
st10
st9
st8
st7
st6
st5
st1
st
10
st
9
st
8
st
7
st
6
st
4
st
5
st
3
st
2
st
1
0
st4
1
0.5
st3
2
1.5
st2
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
2.5
stations
C: Cumacea
D: Euphausiid
3
4
3.5
3
2.5
2
1.5
1
0.5
0
2.5
2
1.5
1
0.5
st9
st7
st5
st3
st1
st9
st10
st8
st7
st6
st5
st4
st3
st2
0
st1
No. of individuals / mL
st5
st4
st3
st2
st1
st
9
st
10
st
8
st
7
st
6
st
5
st
4
st
3
st
2
st
1
0
stations
stations
E: Protozoa
F: Cladocera
3
1.5
2.5
2
1
1.5
1
0.5
0.5
0
Station
st10
st9
st8
st7
st6
st5
st4
st3
st2
st1
st
10
st
9
st
6
st
7
st
8
0
st
3
st
4
st
5
st
1
st
2
-0.5
stations
G: Insecta
H: Nematoda
Fig. 2: Spatial differences in the abundance (mean±SD, n = 60) of zooplankton in the Azuabie Creek of the upper Bonny Estuary
of the Niger Delta
31
Int. J. Fish. Aquat. Sci., 2(2): 29-37, 2013
Table 1: Checklist of the zooplankton from Azuabie creek, upper Bonny estuary
Station
------------------------------------------------------------------------------------------------------------------------------AXA
1
2
3
4
5
6
7
8
9
10
Copepod
Calanoid nauplius
+
+
+
+
+
+
+
+
+
+
Calanus finmarchicus
+
+
+
+
+
+
+
+
+
+
Calanus finmarchicus metanauplius +
+
+
+
+
+
+
+
+
+
Calanusfinmarchicus nauplius
+
+
+
+
+
+
+
+
+
+
Centropages typicus
+
+
+
+
+
+
+
+
+
+
Cyclopinalongicornis
+
+
+
+
+
+
+
+
+
+
Cyclopoid nauplius
+
+
+
+
+
+
+
+
+
+
Eurytemora hirundoides
+
+
+
+
+
+
+
+
+
+
Isias clavipes
+
+
+
+
+
+
+
+
+
Macrosetella gracilis
+
+
+
+
+
+
+
+
+
+
Macrosetella rosea
+
+
+
+
+
+
+
+
+
+
Metridia lucens
+
+
+
+
+
+
+
+
+
+
Microsetella norvegica
+
+
+
+
+
+
+
+
+
+
Oithona helgolandica
+
+
+
+
+
+
+
+
+
Oncaea venusta
+
+
+
+
+
+
+
+
+
Paracalanus parvus
+
+
+
+
+
+
+
+
+
+
Parathalestris croni
+
+
+
+
+
+
+
+
Pseudocalanus elongates
+
+
+
+
+
+
+
+
+
+
Rhincalanus nasutus
+
+
+
+
+
+
+
+
+
Temora longicormis
+
+
+
+
+
+
+
+
+
+
Euphausiacea
Euphausiid nauplius
+
+
+
+
Thysanoessa longicaudata
+
+
Nematoda
Nematode
+
+
+
Spionid
Larva
+
+
+
+
+
+
+
+
+
Cladocera
Evedne spinifera
+
+
+
+
+
+
Daphnia sp
+
Bosmina sp
+
+
Penilia avirostris
+
+
Protozoa
Euplotes sp
+
+
Cresis sp
+
+
+
+
+
+
+
+
+
+
Insecta
Chironomid larva
+
+
+
Arachnactis larva
+
+
Cydippid larva
+
Cumaceane
Diastylis tumida
+
+
+
+
+
+
+
+
+
Hemilampropsrosea
+
+
+
+
+
+
+
+
+
+
+ = Present; - = Absent
Data analysis: Univariate indices of the zooplankton
communities such as Margalef richness index (d),
Pielou evenness index (J), Shannon Wiener diversity
index (H’) and Simpson’s dominance index (λ) were
calculated as follows:
Two-way ANOVA with replicate was used for
statistical analysis of zooplankton taxonomic groups.
Where ANOVA result showed a significant difference,
Bonferoni test were performed for mean separation.
PRIMER (Plymouth Routines in Multivariate
Experimental Research) and MINITAB (R14) was used
to carry out the statistical analysis.
H’ = - ∑ pi x (log 2 pi)
J = H’/ log 2 Si
d = (S-1) log 2 N
λ = ∑ (pi) 2
RESULTS AND DISCUSSION
A total of 35 species of zooplankton belonging to
eight
major
taxonomical
groups (Copepoda,
euphausiaceae, nematoda, spionidae, cladocera,
cumaceane, protozoa and insect) were recorded during
the study periods (Table 1). Out of the total number, 20
species representing 57.14% belonged to the class
where,
N = Abundance
S = Number of species
Pi = The proportion of abundance (n) species from
total zooplankton abundance (N).
32
Int. J. Fish. Aquat. Sci., 2(2): 29-37, 2013
100
8
80
6
60
4
40
2
20
Dec
Feb
Dec
Feb
Oct
Aug
Apr
Mar
Jan
Feb
Dec
Oct
Nov
Sept
Jul
Aug
Jun
Apr
May
Jun
0
0
m onths
m onths
A: Copepoda
B: Spionid
3
0.8
2.5
0.6
0.4
1
0.2
0.5
Oct
Aug
Apr
Feb
Dec
Oct
Aug
Jun
Jun
0
0
Apr
No. of individuals / mL
2
1.5
months
m onths
C: Cumacea
D: Euphausiid
Apr
Feb
Dec
Oct
0
Aug
0
Jun
1
0.5
Apr
1
0.5
Feb
2
1.5
Dec
2
1.5
Oct
3
2.5
Aug
3
2.5
Jun
3.5
stations
m onths
E: Protozoa
F: Cladocera
2.5
1.4
2
1.2
1
1.5
0.8
1
0.6
0.5
0.4
0.2
Feb
Dec
Oct
Aug
Apr
m onths
Jun
0
Feb
Dec
Oct
Aug
Jun
Apr
0
m onths
G: Insecta
H: Nematoda
Fig. 3: Monthly variation in abundance (mean±SD, n=50) of zooplankton in the Azuabie Creek, upper Bonny Estuary of the
Niger Delta
copepoda; 2 species (5.71%) represented the class
euphausiaceae; 1 species (2.86%) represented class
spionidae; 2 species (5.71%) belonged to the class
protozoa; 4 species (11.43%) belonged to the class
cladocera; 3 species (8.57%) belonged to the class
insecta, 2 species (5.71%) belonged to cumaceane
while 1 species (2.86%) represented the class
nematoda. The most common genera in the class
copepoda were the Cyclops and Calanus; whilst the
most common of the calanoid were Temora metridia
and Macrosetella. In terms of abundance, the highest
number of occurrence found was the class copepoda
(88.95%), followed by cumacean (2.76%); cladocera
(2.35%), protozoa (1.99%), spionidae (1.63%), insecta
(1.28%); nematoda (0.76%) and euphausiid (0.26%).
The highest mean abundance of copepods was
recorded at station 3 with the least value at station 8
(Fig. 2A). Insecta, nematode and spionidae also had the
highest mean numbers at station 3, but the lowest
values for these groups was obtained from station 5
33
Int. J. Fish. Aquat. Sci., 2(2): 29-37, 2013
Table 2: Two-way ANOVA to test for significant differences in some zooplankton taxa
Copepoda
Spionidae
--------------------------------------------------Source
df
MS
F
MS
F
Location
9
3.24
09.38
0.958
0.63
Time
11
114.1
288.58
0.503
5.57
Loc x Time
99
5.227
13.22
0.193
2.14
Error
480
0.395
0.0902
Total
599
Protozoa
Cladocera
-----------------------------------------------------Source
df
MS
F
MS
F
Location
9
1.874
16.85
2.993
26.67
Time
11
2.703
24.30
1.543
13.75
Loc x Time
99
0.197
1.77
0.496
4.42
Error
480
0.111
0.112
Total
599
p≤0.001 for all F-values for all levels of comparison
(Fig. 2B, G and H). Stations 7, 8, 9 and 10 had the
highest abundances of cumacea, euphausiid, protozoan
and cladocera respectively. ANOVA showed significant
differences for all zooplankton groups between station
and months as well as significant interactions (p<0.001,
Table 2).
The mean density of copepods reached a peak in
the rainy season month of September and the lowest
was in the dry season month of December (Fig. 3A).
Cladocera, euphausiid, insecta and nematoda were
generally more abundant in the wet season months
(April to October) than the dry season months (Fig. 3D,
F, G and H). On the other hand, cumacea and protozoa
had higher densities in the dry season months of
November to March (Fig. 3B and E). Spionid
abundances did not show appreciable monthly
variations (Fig. 3B). There were significant differences
between months (p<0.001) for all the zooplankton taxa
(Table 2).
The 35 species of zooplankton (belonging to 8
taxonomical groups) recorded in this study was lower
than the 62 species (from 13 taxonomic groups)
reported by Ekeh (2005) for the Amadi creek. The
zooplankton community was dominated by copepoda.
This is in conformity with other studies carried out in
the Niger Delta Waters (Environment Canada, 1996;
RPI, 1985; IPS, 1991; Ogamba et al., 2005; Ekeh,
2005). The entire area was dominated by copepoda
(58.82%); cladocera (11.76%); insecta (8.82%);
euphausiid (5.88%); cumaceane (5.88%); nematoda,
spionidae and protozoa 2.94% each. Low abundance,
composition and diversity recorded in this study have
been greatly affected by pollutant, as well as instability
possibly arising from municipal and industrial waste
input into the creek.
The community indices for zooplankton are shown
Fig. 4 and 5. Marglef species richness index ranged
from 0.78±0.46 at station 5 to 1.85±0.45 at station 9.
Shannon Weiner diversity index and Pielou’s evenness
measure had their highest values at Station 9 and lowest
in station 1. The values of Simpson’s dominance index
were broadly similar at stations 1, 4, 5 and 6 and these
Cumaceae
--------------------------MS
F
1.959
26.37
2.049
27.57
0.190
2.55
0.0743
Euphausiid
------------------------------MS
F
0.1616
7.89
0.0936
4.57
0.0713
3.48
0.0205
Insecta
-------------------------MS
F
2.6291
56.28
0.0189
21.81
0.2983
6.39
0.0467
Nematoda
------------------------------MS
F
0.6184
18.61
0.7714
23.22
0.1556
4.68
0.0332
were higher than the other sites with an overall range of
0.59 to 0.83 (Fig. 4). The wet season months appear to
have higher species richness, diversity and evenness but
low dominance (Fig. 5). All the community indices for
zooplankton showed significant difference both in
space and time (p<0.001). The spatial and temporal
variability in the zooplankton community indices agree
with previously reported patterns by Environment
Canada (1996), Edoghotu (1998) and Ogamba et al.
(2005).
The relationships of zooplankton taxa with
phytoplankton classes and water physic-chemical
variables (Ekeh, 2010) were determined by calculating
the product moment correlation coefficients (Table 3).
Copepod had positive significant relationship with
bacillariophyceae as well as pH, conductivity, TDS and
BOD; negative significant relationship was also
recorded with the same class and some heavy metals
studied during the survey (Zn, Al and Cr). The class
spionidae had positive significant relationship
bacillariophyceae, cyanophyceae and NH 3 ..Cladocera
had a negative significant relationship with
temperature, DO while positive significant relationship
was recorded between salinity, NH 3. . Insecta showed a
positive significant relationship with bacillariophyceae
salinity, NH 3 and negative correlation with DO.
Nematoda also showed a positive significant
relationship with bacillariophyceae but no significant
relationship at all with any of the physicochemical
parameters studied; while cumaceaen showed a
negative significant relationship with cyanophyceae and
positive significant relationship with DO. Euphausiid,
also showed positive significant relationship with
turbidity, Cr, Fe and Zn while a negative significant
relationship was also recorded with temperature.
Positive and negative relationships were also recorded
among the physicochemical parameters and the
zooplankton.
In conclusion, the dynamics of the zooplankton
community of the Azuabie creek is influenced by
spatial differences in contaminant inputs from human
and industrial activities in its catchment as well as
34
Int. J. Fish. Aquat. Sci., 2(2): 29-37, 2013
Fig. 4: Spatial variation of zooplankton community indices in Azuabie Creek, upper Bonny Estuary
Fig. 5: Seasonal variation of zooplankton community indices in Azuabie Creek, upper Bonny Estuary
35
Int. J. Fish. Aquat. Sci., 2(2): 29-37, 2013
Table 3: Correlation coefficients (r) for zooplankton taxa and water quality variables
Temp
pH
Cond
TDS
DO
Copepod
0.453
0.665
0.685
0.596
-0.095
Euphausiid
-0.639
-0.493
-0.464
-0.439
-0.506
Spionidae
0.087
0.154
-0.023
-0.169
-0.452
Protozoa
-0.181
-0.13
-0.252
-0.165
-0.148
Cladocera
-0.508
-0.398
-0.322
-0.301
-0.01
Insecta
-0.221
-0.049
-0.124
-0.243
-0.542
Nematoda
-0.194
0.138
0.159
0.128
-0.182
Cumaceane -0.481
-0.219
-0.023
-0.024
0.561
NH 3
Fe
Zn
Cu
Pb
Copepod
0.474
-0.781
-0.578
-0.045
-0.448
Euphausiid
0.063
0.77
0.554
-0.041
0.178
Spionidae
0.642
-0.15
-0.253
-0.089
-0.436
Protozoa
0.179
0.425
0.219
-0.471
-0.053
Cladocera
-0.053
0.162
0.121
0.398
-0.231
Insecta
0.523
0.063
-0.017
0.358
-0.236
Nematoda
0.402
-0.114
-0.002
0.022
-0.23
Cumaceane -0.347
0.043
0.392
0.142
0.36
natural variations in the physicochemical along the
upstream-downstream gradient. Seasonal differences in
run-off inputs due to precipitation and phytoplankton
abundances also had effects on the zooplankton
community.
Turb
-0.189
0.611
0.47
0.51
0.476
0.648
0.468
-0.017
Al
-0.613
0.331
-0.479
0.164
-0.111
-0.234
-0.199
0.302
Sal
0.617
-0.451
-0.148
-0.289
-0.381
-0.232
0.056
-0.049
Cd
-0.269
-0.226
-0.247
-0.096
-0.3
-0.266
-0.232
0.407
BOD
0.307
0.260
0.435
0.21
-0.01
0.482
0.326
-0.447
Cr
-0.655
0.704
0.018
0.35
-0.036
0.181
-0.2
-0.334
THC
-0.44
0.456
-0.137
0.081
-0.265
0.025
-0.202
-0.046
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Thesis, Rivers State University of Science and
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communities in azuabie creek, upper bonny estuary.
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ACKNOWLEDGMENT
We are grateful to Karibi N. Bob-Manuel for his
kind assistance during the laboratory analysis of
samples.
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