TITLE PAGE
SEASONAL DYNAMICS OF PHYTOPLANKTON ABUNDANCE AND DIVERSITY IN
AJIWA RESERVOIR KATSINA STATE, NIGERIA
*Usman, L. U. Department of Biology, Umaru Musa Yar’adua University Katsina,
Nigeria. Email: [email protected] (+2348035166937)
*Corresponding author
Prof. Adakole, J. A. Department of Biological Sciences, Ahmadu Bello University
Zaria, Nigeria. Email: [email protected]
Dr. Gadzama, I.M.K. Department of Biological Sciences, Ahmadu Bello University
Zaria, Nigeria. Email:[email protected]
Date of submission: 14th November, 2016
Number of tables: two
Number of figures: six
Total word count: 3,808 words
1
SEASONAL DYNAMICS OF PHYTOPLANKTON ABUNDANCE AND DIVERSITY IN
AJIWA RESERVOIR KATSINA STATE, NIGERIA
*Usman, L. U.1; Adakole, J. A.2 and Gadzama, I.M.K.2
1. Department of Biology, Umaru Musa Yar’adua University Katsina, Nigeria
2. Department of Biological Sciences, Ahmadu Bello University Zaria, Nigeria
*Corresponding author: [email protected] (08035166937)
ABSTRACT
Studies on the Seasonal Dynamics of phytoplankton Abundance and Diversity in Ajiwa
reservoir katsina state, Nigeria was carried out from September, 2014 to August, 2015.
Phytoplankton samples were collected with the aid of plankton net at 5 different sampling
locations once monthly. Samples were preserved with 5ml of lugol’s solution in labelled
plastic containers in the field. The preserved samples were allowed to settle first in the
sampling bottle, then about two-third of the water sample was decanted into a beaker to
concentrate the phytoplankton specimen. 1ml of the phytoplankton subsample was placed
in a Petri-dish and mounted under the microscope for viewing with various magnifications.
Identification and counting was done using standard keys through direct microscopy. The
result indicated the presence of 40 species of phytoplankton belonging to 5 major classes,
viz: Chlorophyceae, Bacillariophyceae, Cyanophyceae, Dinophyceae and Euglenophyceae.
The dominant phytoplankton was the Chlorophyceae (40.13%), followed in order by
Bacillariophyceae (23.94%), Cyanophyceae (19.98%), Euglenophyceae (8.41%) and
Dinophyceae (7.58%). Phytoplankton species showed oscillating as well as stable seasonal
patterns of occurrence. Each Phytoplankton taxa showed significant numerical differences
between the wet and dry season. The observed seasonal changes could be attributed to
periods of concentrations of nutrients and stability in growth factors of phytoplankton.
Keywords: Ajiwa reservoir, Abundance, Distribution, Eutrophication,
Phytoplankton, Seasonal variation.
2
INTRODUCTION
Phytoplankton community’s seasonal succession is a well- investigated phenomenon in
aquatic ecology and several studies have described the patterns and the underlying
mechanisms of the seasonal dynamics in freshwater (Medley and Havel, 2007).
Phytoplankton research focuses on the eutrophication of lakes because they are sensitive
aquatic organisms and their community structure could reflect the eutrophic situation in a
short time (Ma, et al., 2012; Adakole, et al, 2012; Pan, et al., 2013; Jing, et al., 2014).
However, phytoplankton are the water ecological system’s important primary producers,
and the foundation of the water ecological system structure. Additionally, algae species
have a strong ability to adapt to the environment and live in all kinds of waters, especially
a few species that can be found under almost any conditions (Ma, et al., 2014). Therefore,
phytoplankton is always used to estimate water quality and eutrophication, and as an early
warning indicator of the safety of an aquatic ecosystem (Gao, et al., 2008; Wang, et al.,
2011; Liu, et al., 2013 ). Planktonic algae were even suited for monitoring very extreme
ecosystems where other types of organisms did not adapt (Taylor, et al., 2007; Gao, et
al., 2013).
The density and species composition of phytoplankton in tropical lakes and reservoirs
demonstrate particular annual biological characteristics (Palmer et al., 1997; Pongswat, et
al., 2004). Phytoplankton succession in open lakes depends on the availability of nutrient,
hydraulic retention time, temperature, light, intensity and transparency. Phytoplankton
communities usually undergo a fairly predictable annual cycle but some species may be
grow explosively and form blooms (Toman, 1996; Hinder et al., 1999; Vaulot, 2001). Light
limitation by high turbidity is another factor that frequently controls phytoplankton growth
either during the whole year or seasonally (Ariyadej et al., 2004; Domingues et al., 2005).
The plankton (zooplankton and phytoplankton) abundance and diversity can be used to
measure water quality. Changes in abundance and diversity of these organisms represent
direct and profound responses to nutrients accumulating from freshwater run-off due to
heavy rainfall and high influx of nutrient from the surrounding farm land which enters into
3
reservoir (Usman, 2016). Phytoplanktons constitute a heterogeneous assemblage of algae
whose distribution and seasonal succession are of interest to limnologists. This is why they
do not only influence the food chain but are also of economic value and biological
significance to man (Araoye and Awolabi, 2005). It is therefore proper that their
occurrence, composition and abundance be matched with opportunities provided in their
environment (Olele and Ekelemu 2008).
Materials and Methods
Study Area
Ajiwa reservoir is located at Batagarawa L. G. A of Katsina state on latitude and longitude
12°54'69" - 12°57'58" N and 7°42'53" - 7°47'50" E (Figure 1). It is in the Sudan savannah
zone of Nigeria with two distinct seasons (wet and dry). The rainy season period on the
average last from May to October and dry season from November to April.
The main purpose of the reservoir is irrigation and water supply to the people of Katsina,
Batagarawa, Mashi, and Mani local government areas. The reservoir was impounded in
1973 and commissioned in 1975. Its major source is river Tagwai. It has original height
of 12m but after being rehabilitated in 1998 the height is now 14.7m, original reservoir
crest length was 880m, but after being rehabilitated reservoir crest length is now 1491.
8m. It also has surface area of 607.0ha. The storage capacity of the water is about
22,730,000m3 (Parkman and Hoskining, 1996). The reservoir serves as source of livelihood
to the nearby communities such as Ajiwa, Masabo, Tsagero, Kwatami, Maje, Gajeren giwa
towns.
Sampling Station
To meet the objectives of the study, the reservoir was divided into five sampling stations
(Figure 1) based on a survey as follows: Station 1 is located around the upper stream site,
where the reservoir is shallower and has a lot of human activities, it has a distance of
about 250m apart from station 2. Station 2 (kanyar bala) is situated around the tower
point where there are less human activities and it has about 300m apart from station 3.
Station 3 is situated around the central basin of the reservoir it has about 250m apart
4
from station 4. Station 4 (Tagwai) is located around the entrance of river Tagwai to the
east of the reservoir and it has distance of about 300m from station 5. Station 5 (Loko) is
located around the downstream part of the reservoir where there is also much domestic
activities.
Phytoplankton sampling and identification
Phytoplankton was sampled from the reservoir with the aid of plankton net. Made of bolting
cloth with a mesh size of 0.01mm, 25cm long, and small bottle contained attached to the
narrow end of the net was sunk beneath the water surface and towed for a distance of 1
meter with it mouth against the water current to permit undisturbed passage of the water
into the bottle. Samples were preserved with 5ml of Lugol’s solution and brought to the
laboratory. The preserved samples were allowed to settle first in the sampling bottle, then
about two-third of the water sample was decanted into a beaker to concentrate the
plankton specimen. 1 ml of the water sample was placed in a Petri-dish and mounted
under the microscope for viewing with various magnifications. Identification of
phytoplankton was carried out by the use of keys and identification guides as described
by (Palmer, 1969; Needham and Needham, 1975; Emi and Andy, 2007).
Figure 1: Map of Ajiwa reservoir katsina, showing sampled stations. (Source: NASA/NOAA
Spot Image 2014).
5
Counting of phytoplankton
For quantitative stimulation, 1ml of the 50ml water collected was counted under the
microscope and the number of algal cells expressed per litre identification was done using
Presscott, (Prescott and Steel, 1975).
Relative abundance of various taxa will be calculated using the formula.
N = a/bn
Where: N = estimated number of species per sample
n = number of species sin sub sample, a = volume of water sample (ml) (50ml)
b = volume (ml) of sub sample (1ml)
The abundance of taxa in each sample was calculated
Using the formula: D = N/V
D = abundance of species (individuals per litre), N = estimated number of species
per sample, V = volume (litres) of water originally filtered.
RESULTS
Seasonal Dynamics of Phytoplankton Communities
Species richness during the sampling period reveal a total of 40 algae taxa in the
phytoplankton samples, viz; Chlorophyceae (15), Bacillariophyceae (12), Cyanophyceae
(8) were the most frequently represented species. They were accompanied by three taxa
of Dinophyceae and two from Euglenophyceae.
However, the reservoir diversity was
essentially limited to Chlorophyta, Bacillariophyta and Cyanophyta being the groups with
highest densities (Table 1).
Chlorophyta accounted for 40.1% of the total 2688 species identified during the study
period. From table 1 it showed that there was higher algal count value in station 1, 2, and
5 with the total of 289, 187 and 362 algal count individual species respectively and lowest
algal count was observed in station 3 and 4 with a total of 64 and 176 individual species
respectively. Rainy season showed highest algal count with mean value of 27.27±1.61
individuals/litre, while dry season showed low algal count from March to April with mean
value of 17.37±1.42individuals/litre (Figure 2). The Chlorophyta community was
constituted
mainly
by
Spirogyra
sp,
Closterium
venus,
Zygnema
fanicum
and
Chlamydomonas sp. The result of the analysis of variance revealed that there was
6
significant difference on the occurrence of species of Chlorophyta along the season, month
and stations (p<0.05).
Chlorophyta (Individual/L)
50
45
40
35
30
Station 1
25
20
Station 2
15
Station 3
10
Station 4
5
Station 5
0
Figure 2: Mean monthly variation of Chlorophyta (Individuals/litre) among sampled
stations in Ajiwa reservoir katsina state.
Table 1: Composition, distribution and abundance of phytoplankton in Ajiwa
reservoir katsina, Nigeria
Taxon
Phytoplanktons
(Individuals/liter)
Chlorophyceae
Cyanophyceae
Bacillariopphyceae
Dinophyceae
Euglenophyceae
Station
1
Station
2
Station
3
Station
4
Station
5
Total
(%)
289
(26.81)
170
(31.66)
179
(27.84)
81
(39.71)
72
(31.86)
791
(29.43)
187
(17.35)
77
(14.34)
82
(12.75)
28
(13.73)
46
(20.35)
420
(15.63)
64
(5.94)
33
(6.15)
60
(9.33)
16
(7.84)
20
(8.85)
193
(7.18)
176
(16.33)
80
(14.90)
122
(18.97)
33
(16.18)
35
(15.49)
446
(16.59)
362
(33.58)
177
(32.96)
200
(31.10)
46
(22.55)
53
(23.45)
838
(31.18)
1078
(40.1)
537
(19.9)
643
(23.9)
204
(7.58)
226
(8.41)
Dominance
_D
Simpson
_1-D
Shannon
_H
Evenness
_e^H/S
0.24
0.76
1.49
0.88
0.26
0.74
1.46
0.86
0.24
0.76
1.52
0.91
0.26
0.74
1.47
0.87
0.23
0.77
1.53
0.93
2688
Cyanophyta (Blue – green algae) accounted for 537 algal count of the total 2688 number
of phytoplankton identified during the study period. It make up the total of 19.9% of the
total phytoplankton taxa count. There was variation along stations. Stations 1 and 5
showed higher algal count of 170 and 177 individual’s species respectively, while lower
algal count was obtained at station 2, 3 and 4 with a total algal count 77, 33 and 80
7
individuals’ species respectively as shown on Table 1. Seasonal variation revealed that
there
was
higher
algal
count
during
rainy
season
with
mean
value
of
12.43±0.89individuals/litre between May to October, while low algal mean count of
8.27±0.44individuals/litre were obtained during dry season between November to April
(Figure 3). Dominant Cyanophyta species in the reservoir were Anabaena circinalis,
Oscillatoria formosa and Nostoc sp.
Cyanophyta (Individual/L)
35
30
25
20
Station 1
15
Station 2
Station 3
10
Station 4
5
Station 5
0
Figure 3: Mean monthly variation of Cyanophyta (Individuals/litre) among sampled
stations in Ajiwa reservoir katsina state.
Monthly variation of Bacillariophyta of Ajiwa reservoir revealed that there was a total of
643 algal count, constituting 23.9%. The highest algal count of 17.70individuals/litre was
recorded during rainy season and the lowest mean count of 12.37individuals/litre was
recorded during dry season (figure 4). Stations 1, 4 and 5 shows higher algal count with
a total of 179, 122 and 200 individuals’ species respectively, while stations 2 and 3 showed
lower algal count of 82 and 60 individuals species respectively (Table 1). It was observed
there was high population density during rainy season period from May to October with
mean value of 17.70±1.07individuals/litre while low count with mean value of
12.33±0.42individuals/litre was observed from November to April in dry season (Figure
4). The dominant Bacillariophyta species in the reservoir during the study period were
8
Navicula placentula, Cyclotella operculata and Cymbella sp. Analysis of variance shows
that there was a significant difference between seasons and months (p<0.05).
Bacillariophyta (Individual/L)
30
25
20
Station 1
15
Station 2
10
Station 3
Station 4
5
Station 5
0
Figure 4: Mean monthly variation of Bacillariophyta (Individuals/litre) among sampled
stations in Ajiwa reservoir katsina state.
Dinophyta revealed that there was a total of 204 algal count (7.5%) of the total
phytoplankton count. Algal count was higher in August (16 algal count), there was high
algal count during rainy season with mean value of 5.73±0.74individuals/litre from
October to May, while dry season month from November to April recorded the lowest algal
count of mean value of 2.33±0.42individuals/litre (Figure 5). Variation with station showed
that stations 1 and 5 recorded higher algal count of 81 and 46 individual species
respectively while stations 2, 3 and 4 recorded lower algal count of 28, 16 and 33 individual
species respectively. Dominant species of Dinophyta in the reservoir during the study
period was Ceratium furca.
9
18
Dinophyta (Individual/L)
16
14
12
10
Station 1
8
Station 2
6
Station 3
4
Station 4
2
Station 5
0
Figure 5: Mean monthly variation of Dinophyta (Individuals/litre) among sampled
stations in Ajiwa reservoir katsina state.
Euglenophyta accounted for 226 algal count of the total 2688 number of phytoplankton
identified during the study period. It make up the total of 8.41% of the total phytoplankton
count. There was variation along stations. Stations 1 and 5 showed higher algal count of
72 and 53 individual’s species respectively, while lower algal count was obtained at station
2, 3 and 4 with a total algal count 46, 20 and 35 individuals’ species respectively as shown
in Table 1. Seasonal variation revealed that there was higher algal count during rainy
season with mean value of 7.10±1.09 individuals/litre between May to October, while low
algal mean count of 2.17±0.41individuals/litre were obtained during dry season between
November to April (Figure 6). Euglena sp and Phacus sp were the two taxa found in the
reservoir during the study period.
10
Euglenophyta (Individual/L)
25
20
15
Station 1
Station 2
10
Station 3
Station 4
5
Station 5
0
Figure 6: Mean monthly variation of Euglenophyta (Individuals/litre) among sampled
stations in Ajiwa reservoir katsina state.
Table 2:Distribution and abundance of Phytoplankton population in Ajiwa reservoir
Katsina State, Nigeria (individual/liter)
Taxon
Chlorophyceae
Spirogyra sp
Oedogonium sp
Chlamydomonas sp
Volvox sp
Staurastrum tetracerum
Scenedesmus dimorphus
Characium acuminatum
Ulothrix sp
Oocystis sp
Closterium venus
Pediastrum simplex
Dictyochloris sp
Tetraedron sp
Euastrum sp
Zygnema fanicum
Cyanophyceae
Anabaena circinalis
Microcystis sp
Phormidium tenue
Oscillatoria Formosa
Calothrix sp
Nostoc sp
Gomphosphaeria sp
Chroococcus sp
Bacillariophyceae
Station 1
Station 2
Station 3
Station 4
Station 5
65
9
58
16
2
0
4
0
5
88
2
6
4
0
30
46
2
16
23
16
0
12
0
2
64
0
2
0
0
4
16
0
12
0
2
0
2
4
0
20
0
2
0
4
2
53
0
24
12
0
2
0
11
8
46
2
0
0
0
18
87
0
66
10
24
8
2
17
2
92
6
0
2
4
42
46
12
0
64
0
48
0
0
37
0
0
22
0
12
0
6
14
2
0
11
0
4
0
2
34
6
0
34
2
2
0
2
89
11
2
65
0
6
2
2
11
Diatoma sp
Melosira listaus
Navicula placentula
Fragilaria sp
Tabellaria fevar
Pinmularia major
Cyclotella operculata
Cymbella sp
Gyrosigma atternuatum
Epithermia zebra
Diatomella sp
Anomoneis sp
Dinophyceae
Spirotaenia sp
Peridinium sp
Ceratium furca
Euglenophyceae
Euglena sp
Phacus sp
14
0
84
0
2
14
38
19
0
4
2
2
10
2
30
2
0
2
24
6
2
2
0
2
22
0
12
0
4
10
2
4
0
4
0
2
28
6
42
0
2
6
23
11
0
0
0
4
34
17
66
2
6
18
47
0
8
0
0
2
10
22
49
6
4
18
0
4
12
4
8
21
8
2
36
64
8
42
4
18
2
31
4
53
0
DISCUSSION
Phytoplankton population indicates the productive status of a water body, because they
are the direct and basic sources of food for most of the organisms in an aquatic habitat.
The results of seasonal variation in phytoplankton population suggest that the favourable
period for primary production in the Ajiwa reservoir is from July to November when
nutrients accumulate from freshwater run-off due to heavy rainfall and high influx of
nutrient from the surrounding farm land. Similar phytoplankton growth due to nutrient
accumulation during rainy season from September to November were observed in Maputo
Bay and Zaria man-made lake, (Paula, et al., 1998; Adakole, et al., 2012). In the present
study, the highest density of phytoplankton was found during the late rainy season,
agreeing with the findings of Santhanam and Srinivasan (1996), who reported highest
phytoplankton cell density during monsoon months in the Tuticorin Bay of India which was
supposed to be caused by continuous discharge of sewage water during the rainy periods.
Lugomela (1995) also found higher primary productivity in different estuarine and coastal
waters during rainy season. The rain cycle thus seems to be the main factor controlling
the seasonality of phytoplankton assemblages in Ajiwa reservoir. Phytoplankton
abundance and taxonomic diversity depend upon the supply of nutrients in natural waters.
12
In the present study, the highest cell density and species diversity of phytoplankton was
found in late rainy season September to November.
Observation of more Chlorophyta species in Ajiwa reservoir than Bacillariophyta conformed
to the typical trend in tropical water bodies, this agreed with the finding of Akomeah, et
al. (2010). Euglenophyta is characteristic of eutrophic or nutrient rich water bodies,
Euglena sp and Phacus sp were found in the reservoir throughout the study period. Twelve
species of Bacillariophyta were recorded during the study period, this correspond with the
findings of
Tiseer, et al. (2008) who recorded ten species of Bacillariophyta, eleven
species of Chlorophyata and one species of Euglenophyta in Samaru stream, Zaria,
Nigeria.
Similarly
Kolo,
et
al.
(2010)
reported
four
groups
of
phytoplankton
(Bacillariophyceace, Chlorophyceace, Cyanophyceace, and Desmidiaceace) in Tagwai
reservoir Minna Nigeria.
CONCLUSIONS
The results of seasonal variation in phytoplankton population suggest that the favourable
period for primary production in the Ajiwa reservoir is from July to November when
nutrients accumulate from freshwater run-off due to heavy rainfall and high influx of
nutrient from the surrounding farm land.
Phytoplankton species showed oscillating as well as stable seasonal patterns of occurrence.
Each Phytoplankton taxa showed significant numerical differences between the wet and
dry season. The observed seasonal changes could be attributed to periods of
concentrations of nutrients and stability in growth factors of phytoplankton.
REFERENCES
1. Adakole, J.A., Abolude, D.S. and Balarabe, M.L. (2012). Assessment of Water Quality
of a Man-Made Lake in Zaria, Nigeria. Proceedings of Taal: The 12th World Lake
Conference: 1373-1382.
2. Akomeah, P.A., Ekhator, O. and Udoka, C. (2010). Dry Season Phytoplankton
CompositionOf Ibiekuma Dam, Ekpoma, Edo State. Ethiopian Journal of
Environmental Studies and Management, (Ekpo, et al., 2015)3:36-40
3. Ariyadej, C., R. Tansakul, P. Tansakul and S. Angsupanich, (2004). Phytoplankton
diversity and its relationships to the physico-chemical environment in the
13
Banglang Reservoir, Yala Province. Songklanakarin J. Sci. Technol., 26: 595607.
4. Domingues, R.B., A. Barbosa and H. Galvao, (2005). Nutrients, light and phytoplankton
succession in a temperate estuary (the Guadiana, South-Western Iberia).
Estuarine CoastalShelfSci. 64:249-260.
5. Emi, Y. and Andy, G. (2007). Phytoplankton Identification Guide.University of Georgia
Marine Education Centre and Aquarium. Pp 342
6. Gao J., Zhou M., Min T.T., Liu Z.W. (2013) Response of the phytoplankton functional
groups to ecological restoration in Huizhou Lake. Ecological Science. 32 (5), 540,
7. Gao, Y., Su Y.X., Qi S.C. (2008). Phytoplankton and evaluation of water quality in Yi
River watershed. J. Lake Sci. 20 (4), 544,
8. Hinder, B., M. Gabathuler, B. Steiner, K. Hanselmann and H.R. Preisig, (1999). Seasonal
dynamics and phytoplankton diversity in high mountain lakes (Jori lakes, Swiss
Alps). J. Limnol., 59: 152-161.
9. Jing M., Li J.Y., Liu M.Y. (2014) Canonical Correspondence Analysis Between
Phytoplankton Community and Environmental Factors in Yangcheng Lake.
Environmental Science and Management. 39 (11), 145.
10. Liu J.J., Qian R.B., Wang B., Xu X. A (2013). Study on the Plankton Features and Water
Quality assessment of Tashan Reservoir in Spring Season. Pollution Control
Technology. 26 (5), 14.
11. Lugomela, C.V., (1995). Spatial and temporal dynamics of phytoplankton biomass and
species composition in Chwaka Bay, Zanzibar. in: interlinkages between eastern
African coastal Ecosystems (ed. M. Hemminga). Report EU TS3-CT 92-0114, N
100, Yerseke. pp. 166-172.
12. Ma S., Wang C.L., Zhang Y.J., Jang X.Y., Reng S.X., Li X.Y., Ma J.M. (2012). Influences
of nitrogen and phosphorus concentration on interactions among chlorelia
Vugaris, daphnia magna and ceratophyllum demersum. Acta Hydrobiologica
Sinica. 36 (1), 66
13. Ma Y., Li G.B., Li J. (2014). Seasonal succession of phytoplankton community and its
relationship with environmental factors of North Temperate Zone water of the
Zhalong wetland, in China. Ecotoxicology, 23 (2), 618.
14. Medley KA, Havel JE (2007). Hydrology and local environmental factors influencing
zooplankton communities in floodplain ponds. Wetlands, 27: 864-872.
15. Needham, J.G. and Needham, P.R. (1975). A Guide to the Study of Freshwater Biology
4th edition, Holden - Day Inc., San Francisco, 1683 pp. NRC (1989). National
Research Council Recommended dietary allowances, 10th ed. Washington, DC,
National Academy Press. P 89.
16. Palmer, C.M., K. Square and R.L. Lewis, (1997). Algae and Water Pollution. Municipal
Environmental Research Laboratory Publisher, Ottawa, Canada.
17. Pan H., Yang Y., Tao R. (2013). Simulation of phytoplankton community succession
mechanism of water improvement. Acta Scientiae Circumstantiae 33 (12), 3309.
14
18. Parkman, B. and Haskoning, M. (1996). Reconstruction of Ajiwa Reservoir Katsina,
Katsina state.Nigeria. Ministry of Water Resources Katsina State. P 1-23
19. Paula, J., I. Pinto, I. Guambe, S. Montaro, D. Gove and J. Guerreiro, (1998). Seasonal
cycle of planktonic communities at Inhaca Island, Southern Mozambique. J
Plankton Res., 20 (11):2165-2178.
19. Pongswat, S., S. Thammathaworn, Y. Peerapornpisal, N. Thanee and C. Somsiri,
(2000). Diversity of phytoplankton in the Rama IX Lake, A Man-Made Lake,
Pathumthani Province, Thailand. Sci. Asia, 30: 261-267.
20. Prescott, G.W. and Steel, J.E. (1975). Ecological Aspects of River Impoundments. In
River Ecology. Whitton, N.B.A (Ed) Pp. 565 – 585.
21. Santhanam, R. and A. Srinivasan, (1996). Impact of dinoflagellates Dinophysis
caudate bloom on the hydrographic and fishery potentials ofTuticorin Bay, South
India.In: Harmful and toxic algal blooms (eds. T. Yasumoto, Y. Oshima and Y.
Fukuyo). Intergovernmental Oceanographic Commission of UNESCO. pp. 41-44.
22. Taylor J.C., Prygiel J., Vosloo A., Rey P.A., Rensburg l.(2007) Can diatom-based
pollution indices be used for biomonitoring in South Africa? A case study of the
Crocodile West and Marico water management area. Hydrobiologia. 592 (1),
455.
23. Tiseer, F.A., Tanimu, Y. and Chia, A.M. (2008), Seasonal Occurrence of Algae and
Physico-chemical Parameters of Samaru Stream, Zaria, Nigeria. Asian Journal of
Earth Sciences, 1(kozak, et al., 2012), 31-37.
24. Toman, M.J., (1996). Physico‐chemical characteristics and seasonal changes of
plankton communities in a river reservoir. Lakes Reservoirs: Res. Manage., 2:
71-76.
25. Usman, L. U. (2016). Some Limnological and Biological Aspects of Ajiwa Reservoir,
Katsina State, Nigeria. (M.Sc. Dissertation). Department of Biological Sciences,
Ahmadu Bello University, Zaria. Pp 103-109
26. Vaulot, D., (2001). Phytoplankton. Macmillan Publishers Ltd., Nature Publishing Group.
http://www.sb-roscoff.fr/Phyto/Reprints/Vaulot_ELS_01.pdf.
27. Wang Y., Liu L.S., Shu J.M. (2011) Community structure of phytoplankton and the
water quality assessment in Lake Baiyang-dian. J. Lake Sci, 23 (4), 575.
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