Available online at http://ajol.info/index.php/ijbcs
Int. J. Biol. Chem. Sci. 7(2): 631-640, April 2013
ISSN 1991-8631
© 2013 International Formulae Group. All rights reserved.
DOI : http://dx.doi.org/10.4314/ijbcs.v7i2.19
Original Paper
http://indexmedicus.afro.who.int
Zooplankton abundance and diversity of fishponds exposed to different
management practices
A.A. ADEDEJI
1*
, I.F. ADENIYI
1
and H. MASUNDIRE
2
1
Department of Zoology, Obafemi Awolowo University, Ile-Ife, Nigeria.
2
Department of Biological Sciences, University of Botswana, Gaborone, Botswana.
*
Corresponding author, E-mail: bbkadedeji@yahoo.com; bbkadedeji@oauife.edu.ng
ABSTRACT
The taxonomic composition and community structure of zooplankton faunae of selected earthen
fishponds in Ife North Local Government Area of Osun State, Nigeria were investigated for a period of two
years sampling every other month. The study was based on three sets of fishponds with regards to fertilization
practice and water flow regime. These include non flow-through ponds that received organic and inorganic
fertilizers (FNF); flow-through ponds that received organic and inorganic fertilizers (FF) and unfertilized flow-
through ponds. The zooplankton fauna of the fishponds comprised of 81 species belonging to three phyla
namely Rotifera (62 species belonging to 16 families and two orders), Arthropoda (6 cladocerans, 2 copepods,
6 ostracods, 4 insecta and one arachnid species) and Protozoa which was represented by only one species.
Zooplankton species richness indices were generally higher in the flow-through ponds than in the non flow
through ponds with some species occurring only in the fertilized flow-through ponds. The flow-through pond
had the highest number of species 54, while the least number of species 37 was recorded from the non flow-
through pond. The fertilized non-flow-through ponds also had the .highest mean abundance of 36762 ± 56162
ind/m
3
, followed by fertilized flow-through ponds (34346 ± 40784 ind/m
3
) and non-fertilized flow-through
ponds (16006 ± 41263 ind/m
3
) descending order. The means in zooplankton abundance among the ponds were,
however, not statistically significant. The fertilized ponds supported zooplankton abundance while continuous
water flow as observed in the flow-through had direct influence on diversity and species richness. Hence to
achieve the desired effect of pond fertilization on its primary productivity, this must be accompanied by
adequate water flowage especially in shallow fish ponds.
© 2013 International Formulae Group. All rights reserved.
Keywords: Zooplankton, community structure, diversity, fish ponds, fertilization.
INTRODUCTION
Zooplankton play important roles in the
energy and material transfer in waterbodies as
the consumers of phytoplankton (Welch,
1992). Garesoupe (1982) and Kibria et al.
(1997) revealed that zooplankton are a
valuable source of protein, amino acids, lipids,
fatty acids and essential minerals and enzymes
needed by aquatic organisms for effective
normal growth and survival. Several studies
have also indicated improved performance of
fish larvae fed natural indigenous live
zooplankton (Lubzen, 1987; Ovie et al., 1993;
Adeyemo et al., 1994) while according to
Alam and Cheah (1993), both live and frozen
A.A.ADEDEJI et al. / Int. J. Biol. Chem. Sci. 7(2): 631-640, 2013
632
zooplankton have also been used in
commercial and experimental aquaculture.
Fertilization of ponds to enhance alga
growth and produce zooplankton suitable for
larval fish is a common practice in Nigeria.
Nutrient increase as a result of pond
fertilization has direct impact on the plankton
community and ultimately the fish biomass
(Sipauba-Tavares et al., 2011). The plankton
biomass and composition in ponds (shallow
waters) fluctuate as a reaction to several
interacting driving force which may include
polymixis, water level changes, weather
conditions, nutrient loading and feeding
management ( Borics et al., 2000). Several
studies have revealed that both quality and
quantity abundance of plankton communities
in fishponds vary from location to location
and pond to pond within the same location
even under similar ecological conditions
(Boyd, 1982; Chowdhury and Mamun, 2006;
Bhuiyan et al., 2008). Factors that affect
plankton distribution and abundance include
season, physical and chemical parameters,
water movement, soil, and biological factors
(Davies et al., 2009).
Therefore, the study aimed at
evaluating zooplankton taxonomic
composition, biomass and community
structure under different pond management
over a period of two years to determine the
effect of pond fertilization and water flowage
on their community structure.
Area of study
The fish ponds investigated in this
study belong to Niger Feeds and Agricultural
Operations Limited (NIFAGOL), one of the
few major commercial fish farms in Osun
State, Nigeria. The fish farm is located in
Yakoyo – Origbo in the northern part of Ife
North Local Government Area (LGA), Osun
State, Nigeria. The LGA is located roughly
between Latitudes 07
0
25′
- 07
0
40′N and
Longitudes 004
0
25′ - 004
0
30′E, on a general
elevation range of 250 – 265 m above mean
sea level. It comprises 18 ponds of varying
sizes, each rectangular in outline and about
2.5 m deep. Only ten out of the18 ponds were
in use during the present study. Water is
supplied into these ponds from a nearby
reservoir with a surface area of 20,000 m
2
(2
hectares).
The aquaculture system being practised
in the farm is the semi-intensive type. Four of
out of the ten in use culture ponds were being
fertilized with both organic fertilizers (chicken
droppings and cow dung) and inorganic
fertilizers (NPK). Supplemental feeding was
also given in small quantity to the stocked
fish. The water retention period for fertilized
ponds was 6 months while the unfertilized
ponds were left undrained. These unfertilized
ponds were open with water flowing through.
The fish stock density for all the ponds was 3
fish/m
2
. The fish were fed twice daily and
their feeds included locally made pellets
(made from mixture of maize, soybeans,
fishmeal, millet, palm kernel cake, groundnut
cake and palm kernel oil) and Brewer’s waste.
The fish being reared in the pond was Clarias
gariepinus.
MATERIALS AND METHODS
Of the eighteen ponds in NIFAGOL
fish farm, only ten ponds were operational
during the present study. Water samples were
collected from six of these ten ponds every
other month over a period of two years from
February 2006 to February 2008. For the
purpose of this study, the six ponds were
grouped into three sets with regard to
fertilization (fertilizer treatment) and water
flowage based on the existing culture
practices. The first sets of two ponds,
fertilized non flow-through ponds (FNF)
received organic and inorganic fertilizers and
were non flow-through. The second sets of
two ponds, fertilized flow-through ponds (FF)
received organic and inorganic fertilizers as
FNF but were flow-through ponds. The third
sets of two ponds, not fertilized flow-through
(NFF) received no fertilizer but were flow-
through ponds.
Thirty litres of water collected from
each pond was filtered and concentrated to 20
mL using a 45µm plankton net. The plankton
concentrate samples were preserved in 5%
A.A.ADEDEJI et al. / Int. J. Biol. Chem. Sci. 7(2): 631-640, 2013
633
formalin to which was added two drops of
Lugol solution for quantitative and qualitative
examination. Planktonic enumeration were
done by introducing 1 mL of the preserved
concentrate plankton samples into a Sedwick-
Rafter counting chamber for examination
through an Olympus BH2 Microscope.
Planktonic identification was done to specific
levels according to Edmondson (1959),
Adeniyi (1978), Akinbuwa and Adeniyi
(1991), Seger et al. (1991, 1993), Akinbuwa,
(1999) and Fernando (2002). The variation in
ponds and seasonal abundance of zooplankton
were analyzed using SPSS16 for windows
(Statistical Software package, SPSS Inc.);
PAST and SYSTAT 13. The analysis involved
descriptive statistics and multivariate statistics
(t test, Kruskal-Wallis Test and Andrews’
Fourier plot). The various indices of
community structure (species richness,
diversity and evenness indices) were all
calculated in accordance with the procedures
of Ludwig and Reynolds (1988). The
relationships between the different ponds
investigated based on zooplankton abundance
were established using cluster analysis (single
linkage method) according to Hedges (1971).
RESULTS
Taxa composition
The zooplankton fauna of the fishponds
comprised of 81 species belonging to three
phyla. There were 62 species of rotifers
belonging to 16 families and two orders. The
arthropods comprised of 6 cladocerans, 2
copepods, 6 ostracods, 4 insects and one
arachnid species. A total of 24 species were
common to all the ponds while some were
restricted in distribution. The restricted
species included Branchionus dimidiatus
inermis and Notholca squamula found only in
fertilized flow-through ponds; Keratella
taurocephala, Lecane ludwigii and
Macrochaetus collinsi brazilensis occurred
only in non-fertilized flow-through ponds. Of
the 24 organisms found to occur most
frequently, 20 of them were rotifers while the
remaining four species were Diaphanosoma
brachyurum, Mesocyclops edax, Cyclocypris
serena and Chironomus sp larva. Some
species showed specific seasonal occurrence,
these include Filinia pejleri, Brachionus
dimidiatus inermis, Keratella taurocephala,
Lepadella patella similis, Albertia sp, Lecane
ungulata, Elosa worrali, Trichocerca
bcristata, Daphnia longiremis, Eucypris
fuscatus, Corethrella sp, Hesperocorixa
obliqua and Hydracaina sp which were
recorded only during the rainy season. While
Horaella brehmi, Brachionus
budapentinensis, Notholca squamula, Lecane
ludwigii, Lecane lunaris, Lecane monostyla
copies, Macrochaetus collinsi braziliensis and
Belostoma sp occurred only during the dry
season.
Distribution pattern, abundance and
community structure
The total number of species per pond
varied from 37 to 54. The flow-through pond
had the highest number of species, 54 while
the least number of species, 37 was recorded
from the non flow-through pond. On the
average, more species were recorded during
the rainy season (with a mean of 41 species
per pond) than during the dry season (with a
mean of 37 species per pond). This trend was
applicable to all the ponds except the fertilized
flow-through ponds where the number of
species recorded during the dry season was
slightly higher (P ≥ 0.05) than the number for
the rainy season. This was evident with the
increase in total number of organisms
recorded for each species from these ponds
except copepods and cladocerans (Figure 1).
Rotifers were most abundant in all the
ponds for both season, followed by copepods
while no species of the class insect was
recorded from the fertilized non flow-through
ponds during the dry season (Figure 1).
Trichocerca cylindrica, with the highest
number of individual per m
3
(188667 ind/ m
3
)
as well as the maximum total number of
organisms per m
3
(210644 ind/ m
3
) was
recorded in the fertilized non-flow-through
pond during the onset of rainy season (April,
2007) and late dry season (February, 2007)
respectively. The fertilized non-flow-through
A.A.ADEDEJI et al. / Int. J. Biol. Chem. Sci. 7(2): 631-640, 2013
634
ponds also had the highest mean abundance of
36762 ± 56162 ind/m
3
, followed by fertilized
flow-through ponds (34346 ± 40784 ind/m
3
)
and non-fertilized flow-through ponds (16006
± 41263 ind/m
3
) descending order. The mean
total abundances among the ponds were not
significantly different. However the
zooplankton fauna in the ponds were more
abundant during the dry season than during
the rainy season (Figure 1). The overall
difference in mean abundance for the
respective species was not significant except
for Cyclops scutifer (P < 0.05). The species
with the highest abundance during the rainy
season was Trichocerca cylindrica (1.02 x 10
4
± 3.67 x 10
4
ind/m
3
) while Anuraeopsis fissa
had the highest value during the dry season
(8008.7 ± 1.30 x 10
4
ind/m
3
). Brachionus
dimidiatus inermis, Keratella taurocephala,
Lecane ungulata, Trichocerca bicristata,
Daphnia longiremis, as well as Hydracarina
each had relatively low abundance during the
dry season while Horaella brehmi,
Brachionus budapestinensis, Notholca
squamula, Lecane ludwigii, Lecane lunaris,
Lecane monostyla copies, Belostoma sp were
characterised by low abundance during the
rainy season.
Zooplankton species richness indices
were generally higher in the flow-through
ponds than in the non flow through ponds
(Table 1), with Margalef index (R
1
) values
ranging from 3.25 (non flow-through pond) to
4.42 (flow-through pond). This suggests that
the flow-through ponds were much richer in
species than the non flow-through ponds. The
zooplankton population in the fertilized flow-
through ponds were more diverse than that of
other investigated ponds with Simpson’s
diversity index of 0.11 and 0.14 and highest
number of very abundant species of 8 and 10
species respectively according to Hill’s
Second diversity index of number (N
2
). These
accounted for 84% and 87% of the recorded
abundance in the respective ponds. The
number of abundant species (based on Hill’s
first diversity number) was also quite high for
the fertilized flow through ponds. Diversity
was very low in pond 1 (fertilized non flow-
through pond) and pond 5 ( non fertilized
flow-through pond) with about 3 to 4 species
accounting for 79%, and 92%, of the recorded
abundance in the ponds respectively.
The Hill’s Evenness indices (E
4
and E
5
)
were above 0.40 for most of the ponds except
Pond 1, thus the relative abundances of
species in the pond did not totally diverge
from evenness and this also confirmed the
dominance of few abundant species in Pond 1.
Inter-pond relationship
The Andrews’ Fourier plot based on
the zooplankton abundance in the ponds
revealed that the zooplankton distribution
among the ponds were quite different over the
period of study (Figure 2). The non-fertilized
flow-through ponds and the fertilized non-
flow-through ponds were however found to
have some similarity in distribution of
zooplankton based on the cluster analysis of
the Morisita similarity index (based on mean
abundance of each zooplankton species)
between the investigated fish ponds (Figure
3). The clusters were found to be based on the
number and abundance of the species that
these ponds have in common. The fertilized
flow-through pond was found to be distinct
having seven zooplankton species
(Brachionus dimidiatus inermis, Notholca
squamula, Euchlanis dilatata, Euchlanis
dilatata macrura, Dicranophorus lutkeni,
lecane monostyla copies and Belostoma sp)
which were not found in other ponds.
Using Kruskal-Wallis Test and Dwass-
Steel-Chritchlow-Fligner Test for all pairwise
comparison also based on zooplankton
abundance, 72 species showed highly
significant variations (P ≤ 0.001) in
abundance among the ponds studied. Of
which 32 species accounted for highly
significant differences between the fertilized
ponds and non-fertilized ponds; 26 species
varied significantly between the fertilized
flow-through and other ponds while the
significant differences between the flow-
through and non-flow-through ponds were due
to 14 species.
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635
Table 1: Zooplankton richness, diversity and evenness of the investigated ponds.
Waterbodies
FNF FF NFF
Index Pond 1 Pond 2 Pond 3 Pond 4 Pond 5 Pond 6
Total number of species (S) 50 37 50 55 51 55
Margalef index (R
1
) 3.86 3.25 3.70 4.33 3.72 4.42
Diversity Indices
Simpson index (λ) 0.35 0.09 0.14 0.11 0.23 0.18
Hill’s First Diversity Number (N
1
) 5.71 15.48 10.89 12.96 5.96 9.70
Hill’s Second Diversity Number (N
2
) 2.88 11.47 7.27 9.32 4.26 5.57
Percentage accounted for by abundant species (%) 79 88 84 87 92 83
Evenness Indices
Hill (E
4
) 0.51 0.74 0.67 0.72 0.72 0.57
Modified Hill (E
5
) 0.40 0.72 0.63 0.70 0.66 0.52
