Journal of Marine Biology
Volume 2015 (2015), Article ID 376986, 9 pages
http://dx.doi.org/10.1155/2015/376986

Research Article

Composition of Periphyton Community on Water Hyacinth (Eichhornia crassipes): In Analysis of Environmental Characteristics at Ejirin Part of Epe Lagoon in Southwestern Nigeria

A. I. Inyang,¹ K. E. Sunday,² and D. I. Nwankwo²

¹Department of Marine Biology, Akwa Ibom State University, Nigeria
²Department of Marine Sciences, University of Lagos, Akoka, Nigeria

Received 7 September 2014; Revised 24 November 2014; Accepted 4 December 2014

Academic Editor: Robert A. Patzner

Copyright © 2015 A. I. Inyang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract.

The composition of periphyton community on water hyacinth was investigated at Ejirin, part of Epe Lagoon, in relation to environmental characteristics from December 2012 to May 2013. A total of 14,536 individuals of 104 species belonging to five divisions were identified, with Bacillariophyta (82.69%), Cyanobacteria (10.43%), Chlorophyta (5.63%), and Euglenophyta (1.15%). The total species abundance observed showed a strong correlation with rainfall () and strongly significant correlation with TDS (; ). Biochemical oxygen demand value remained (BOD) 4.8 mg/L while Shannon-Wiener index value remained (. The presence of the following organisms could be used as an indicator of environmentally stressed aquatic ecosystem: euglenoids, blue green algae, Nitzschia palea, Surirella sp., Pinnularia sp., Gomphonema parvulum, Mougeotia sp., Spirogyra sp., Trachelomonas affinis (Lemm.), and T. ensifera Daday; T. gibberosa Playf. and Phormidium articulatum; Lyngbya intermedia; Cymbella ventricosa; Eunotia arcus; Surirella linearis and Closterium parvulum Nag.

1. Introduction

Water hyacinth (Eichhornia crassipes) was introduced into the Nigerian coastal waters in September 1984 from Porto Novo Creek (Benin Republic) and has continued to flourish. Schlorin [1] stated that water hyacinth is a sensitive indicator of environmental status of certain tropical waters. Water hyacinth plant provides suitable surfaces for the development of periphyton as well as aquatic fauna on floating leaves, hanging roots, and creeping stems. According to Egborge [2], water hyacinth harbours a variety of organisms which include algae, rotifers, nematodes, annelids, molluscs, hydracerids, cladocerans, copepod, conchostracans, isopod, amphipods, crabs, and fishes. Organisms such as snails and mayflies affect the periphyton species assemblage, biomass, and productivity [3].

The algae found in water bodies depend on cells, which may either float on the surface or grow on submerged objects, and are divided into two groups, namely, phytoplankton and periphyton [4, 5]. The term “periphyton,” coined by Behning and Cooke [6, 7], was derived from two Greek words, “peri,” meaning “round,” and “phyton,” meaning plant. Periphyton has become a universally accepted expression for all organisms that are attached to a submerged substrate and generally dominated by photosynthetic organism which may be unicellular, colonial, or filamentous species from a variety of prokaryotic and eukaryotic phyla. As applied to this work, Wetzel [8] defined periphyton as the micro- “floral” community living attached to the substrate inside water. This microfloral community plays an important role in water bodies, not only by being important primary producers [9, 10] and serving as an energy source for higher trophic level [11], but also by affecting the nutrient turnover [12] and the transfer of nutrients between the benthic and the pelagic zone [13]. Several works on substrate-mediated effect on periphyton biomass and composition have been reported [14, 15] and its usage as an important indicator of the health of aquatic systems [16–18]. These organisms are useful indicator groups for pollution bioassessment due to their sensitivity to pollution. Since the composition of periphyton community on water hyacinth at Ejirin has not been assessed, it is therefore important to document its composition and abundance in relation to environmental characteristics. This study will serve as a source of data background and information on water quality and periphyton abundance and composition.

1.1. Study Area

The study site, Ejirin (Figure 1), located (6°89′′N, 3°38′′E) is part of Epe Lagoon, freshwater and nontidal lagoon. It is sandwiched between Lekki Lagoon to the east and Lagos Lagoon to the west. It experiences the same hydroclimatic conditions as the rest of southwestern Nigeria such that there are two main seasons (wet and dry). The littoral vegetation found there is dominantly Raffia palm and some dotted mangrove, while on surface water some floating macrophyte like water hyacinth (Eichhornia crassipes) dominates. The people there are mainly artisanal fishermen, sand miners, and petty traders.

Figure 1: Map of Epe Lagoon showing the study area at Ejirin.

2. Materials and Methods

2.1. Physicochemical Characteristics

Water samples were collected on each trip between 09:00 and 13:00 and stored in 250 mL well labelled plastic bottles and transported to the laboratory in an ice chest. Surface water temperatures were measured in situ using a mercury-in-glass thermometer and recorded to the nearest 0.1°C. Transparency was determined using 20 cm white painted Secchi disc while pH values were measured using a Graffin digital pH meter. Dissolved oxygen concentration was determined by unmodified Winkler method [19], conductivity was assessed using the meter (Philips PW9505), and chemical oxygen demand and biochemical oxygen demand values were determined using the method described in APHA [20]. Reactive nitrogen, reactive phosphorus, sulphate, and silicate were measured as described by APHA [20]. Rainfall data was obtained from the Federal Meteorological Department, Oshodi, Lagos.

2.2. Determination of Periphyton Biomass

Healthy plants were carefully selected to ensure uniformity in size before putting each into plastic containers with 500 mL of tap water. The attached algae were removed mechanically by shaking vigorously in water as suggested by Foerster and Schlichting [21] and preserved in a well labelled plastic container with 4% unbuffered formalin added to fix the periphyton sample. Another 500 mL container was filled with an unfixed sample for chlorophyll analysis. Chlorophyll was determined by fluorometric method as described by APHA [20].

2.3. Analysis of Biological Characteristics

Periphyton samples were thoroughly investigated using CHA and CHB binocular microscope with a calibrated eye piece, noting all fields. Counting was done using a microtransect drop count, and 10 drops of periphyton samples were investigated for each month as described by [22]. All organisms, unicels, filaments, and coenobia were counted as one and recorded as per mL. Appropriate texts such as [23–26] (Biggs and Kilroy) were used to aid in the identification of periphyton. Two community structure parameters were used to determine possible response of the periphyton flora to environmental stress. These were as follows.

(i) Shannon-Wiener diversity index (), proposed by Shannon-Wiener in 1963: it is given by

where is Shannon-Wiener index, is the total number of individuals in the population, is proportion that the th species represent the total number of individuals in the sampling space, is summation, and represents counts denoting th species ranging from 1 to .

(ii) Species richness index (), proposed by Margalef in 1951: it is given by

where is species richness index, is the number of species in the population, and is the total number of individuals in species.

2.4. Statistical Analysis

Statistical analysis was carried out with the aid of SPSS (version 17) and PAST (version 3) statistical tools. Correction coefficient [27] was used to evaluate relationship between periphyton abundance and some environmental variables (temperature, salinity, total monthly rainfall, TDS, TSS, transparency, pH, and micronutrients). It is given by Spearman rank correlation:

where is the correlation coefficient, is the sum of squares of difference of the ranks, and is the number of months.

-test analysis was carried out to evaluate statistical difference () in seasonal (wet and dry) abundance of periphyton community. Standard deviation and mean analysis were also evaluated.

3. Result

The data for physicochemical features at Ejirin Creek from December 2012 to May 2013 showed seasonal variation as presented in Table 1. Surface water temperature peaked 33.01°C in May and lower value of 28°C in January with a mean value of 30°C. The surface water temperature showed a strong significant correlation with rainfall (; ) (Table 3). The surface water pH was acidic throughout the sampling period (pH ≤ 6.6) with a mean value of 6.39. Conductivity peaked 0.35 μs/cm in May and lower value of 0.006 μs/cm in March, with a mean value of 0.184 μs/cm. Conductivity showed a strong positive correlation with rainfall () and with periphyton chlorophyll (). Transparency values were high in the dry months and low in the wet months. This corresponds to the rainfall pattern encountered during the study. The water remained fresh throughout the study period with salinity value .

Table 1: Status of physicochemical parameters at Ejirin, part of Epe Lagoon, from December 2012 to May 2013.

Parameters
December
January
February
March
April
May
Mean
Standard deviation

Water temp. (°C)
29.3
28.3
29
30.6
29.3
33.1
29.93
1.72

Transparency (cm)
43
57
41.5
38.5
34
31
40.8
9.11

Depth (cm)
25
28
30
27
30
26
27.7
2.07

pH
6.639
6.15
6.22
6.45
6.6
6.5
6.39
0.17

Conductivity (µs/cm)
0.192
0.154
0.2
0.006
0.2
0.35
0.18
0.11

TSS (mg/L)
55
66
170
73
1
1.1
61.01
62.09

TDS (mg/L)
0.65
79
87
141
119
161
97.94
56.95

Rainfall (mm)
13.2
0
28
50.1
165.3
340.8
99.57
132.25

Salinity ()
0
0
0
0.01
0
0
0.002
0.004

Nitrate (mg/L)
0.32
0.11
0.08
0.08
0.12
0.07
0.13
0.095

Phosphate (mg/L)
0.78
0.65
0.59
1.08
0.71
0.59
0.73
0.18

Sulphate (mg/L)
1.20
0.80
1.26
1.30
1.21
1.26
1.17
0.19

Silicate (mg/L)
0.40
0.80
0.11
0.05
0.05
0.06
0.25
0.30

Periphyton chl. a (mg/L)

0.003
0.001
0.003
0.003
0.0023
0.00096

Biological oxygen demand (mg/L)
4.8
0.4
2
3.7
2.2
0.8
2.32
1.68

Chemical oxygen demand (mg/L)
15
16
20
37
32
32
25.33
9.46

Dissolved oxygen (mg/L)
6.13
10
4.5
5
5.8
6
6.24
1.95

The micronutrients varied throughout the study periods with reactive nitrate (NO₃-N ≤ 0.32), reactive phosphate (PO₄-P ≤ 0.78), silicate (SiO₃ ≤ 0.80), and sulphate (≤1.30). Periphyton chlorophyll reached a peak value (0.003 mg/L) recorded in February and April while its lower value (0.001 mg/L) was recorded in March, with a mean value of 0.0023 mg/L. Biochemical oxygen demand reached a peak value (4.8 mg/L) recorded in December and the lowest value (0.4 mg/L) was recorded in January, with a mean value of 2.317 mg/L. Chemical oxygen demand value ranged between 15 mg/L (December) and 37 mg/L (March), with a mean value of 2.31 mg/L. Dissolved oxygen demand (DO) value reached a peak value (10 mg/L) recorded in January and a lower value (4.5 mg/L) was recorded in February, with a mean value of 6.24 mg/L.

The checklist of the periphyton species between December 2012 and May 2013 is presented in Table 2. A total of 14, 536 individuals of 104 species were recorded throughout the study period. The total number of taxa varied from 24 in December to 26 in January, 23 in February, 63 in March, 41 in April, and 49 in May. Diatom populations during both seasons were dominated by 10 centric diatoms and 34 pennate diatoms and a total of 19 species were recorded for Cyanobacteria. Five divisions were recorded with their percentage of occurrence: Bacillariophyta (82.69%), Cyanobacteria (10.43%), Chlorophyta (5.63%), and Euglenophyta (1.15%). The total amount of periphyton abundance shows a strong positive correlation with water temperature (), pH (), rainfall (), and sulphate (). It also strongly correlates significantly with TDS (; ) and with transparency (; ). There was greater species richness during wet months than dry months with a value . Shannon-Wiener diversity index value was observed to be (Table 4).

Table 2: Species abundance distribution of periphyton at Ejirin, part of Epe Lagoon, from December 2012 to May 2013.

Periphyton taxa
December
(CellsmL⁻¹)
January
(CellsmL⁻¹)
February
(CellsmL⁻¹)
March
(CellsmL⁻¹)
April
(CellsmL⁻¹)
May
(CellsmL⁻¹)

Phylum: Cyanophyta

    Class: Cyanophyceae

        Order I: Chroococcales

            Chroococcus major
24

47

            Chroococcus gardneri

23

23

            Chroococcus occidentalis

28

            Chroococcus deltoids

51

            Chroococcus mediocris

33
37

            Chroococcus mipitanensis

36

            Merismopedia punctata Meyen
7

21

            Chlorella subsala Lemm.

14

            Chlorogloea gardneri

23

            Cyanothece sp.

14

            Gomphosphaeria sp.

22

            Aphanocapsa conferta

43
32

            Anacystis sp.

14

            Aphanothece comasii

22

            Aphanothece variabilis

8

        Order II: Nostocales

            Anabaena sp. Bory ex Bornet

42
18
37
46

        Order III: Oscillatoriales

            Lyngbya intermedia Agardh ex Gomont

58
179
147
201
187

            Phormidium articulatum

42

34

            Komvophoron sp.

18

Phylum: Euglenophyta

    Class: Euglenophyceae

        Order I: Euglenales

            Euglena oxyuris var. charkowiensis
8

13
8
11

            Euglena gracilis Klebs

12

            Phacus orbicularis Hubner

14

            Phacus caudatus Hubner

13

            Phacus triqueter
13

            Trachelomonas affinis (Lemm.)

12

12

            Trachelomonas ensifera Daday

9
16

            Trachelomonas gibberosa Playf.

13

13

Phylum: Bacillariophyta

    Class: Bacillariophyceae

        Order I: Centrales

            Aulacoseira granulata var. angustissima f. curvata Simon
172
41
301
342
407
524

            Aulacoseira granulate var. angustissima f. spiralis O. Mull.
181
101
309
498
587
651

            Aulacoseira islandica subsp. Helvetica O. Mull.
98
40
134
192
271
285

            Aulacoseira granulata (Ehr.)
189
115
337
414
541
702

            Aulacoseira italica (Ehr.)
13
33
103
175
203
198

            Hemidiscus cuneiformis

29

35

21

            Cyclotella meneghiniana Kütz. ex Br.
72
18

108
67

            Cocconeis pediculus Ehr.
48

62
48
98
72

            Rhizosolenia longiseta

12
11

            Rhizosolenia hebetata Bail.

14

        Order II: Pennales

            Eunotia arcus Ehr.
72

37
27
37

            Diatoma tenuis Bory

117
121
113
67

            Cymbella ventricosa Agardh
31
21

24
27
34

            Surirella debesi Turpin

24

27

            Surirella robusta var. splendida

21

            Surirella robusta var. armata

17

            Surirella linearis Turpin
19

47
38
27
31

            Synedra acus Ehr.

21

31

            Synedra ulna var. contracta Ehr.
22

18
21

38

            Staurosirella leptostauron

14

            Asterionella formosa Hassall

21

207

            Gyrosigma scalproides Hassall

19

            Gyrosigma attenuatum Hassall

16
13

            Gomphonema parvulum Ehr.
21
17

24
36
31

            Navicula lanceolata Bory

98

            Navicula pupula Kütz. var. rectangularis Grun. Compr.

32

            Navicula radiosa
19

28
52

            Navicula margalithii
23

57
38
37

            Stauroneis anceps

27

            Nitzschiaacicularis Kütz.

52
37
33

            Nitzschia dissipata

18

28
27

            Nitzschia intermedia
31
31
34
54
42
41

            Nitzschia inconspicua
31

32

38
51

            Nitzschia closterium

31
32

            Nitzschia gracilis

31

29
44

            Pinnularia acrosphaeria (Breb.) var. minor Kütz.

27

36

            Pinnularia gibba

17
31

            Pseudostaurosira brevistriata

11

            Amphora ovalis Kütz.

47
52

            Epithemia argus var. longicornis Grun.

39
19

            Epithemia sorex

47

            Rhopalodia operculata (Ehr.) Müller

21

            Achnanthidium lanceolatum Kütz.
21
16

            Achnanthidium linearis Kütz.

12
27

Phylum: Chlorophyta

    Class: Chlorophyceae

        Order I: Chlorococcales

            Ankistrodesmus falcatus Ralfs var. mirabilis West f. longiseta Nygaard

29

            Ankistrodesmus falcatus Ralfs var. spirilliformis West

32

            Ankistrodesmus falcatus Ralfs

18

            Ankistrodesmus falcatus Ralfs var. setiformis Nygaard f. brevis Nygaard

22

            Ankistrodesmus gracilis Corda

21

            Ankistrodesmus braianus

24

            Scenedesmus armatus Chodat
19
23

11
13

            Scenedesmus perforates Meyen

31

            Scenedesmus dispar f. canobe 2-cellulaire

11

14
12
22

            Scenedesmus quadricauda

11
19
17

            Actinastrum Hantzschii Lagerheim

11

            Kirchneriella sp. Schmidle

7

            Tetrastrum stauroeniaeforme

16

            Tetrastrum heteracanthum f. epine par cellule

14
13

            Selenastrum gracile Reinsch

13

            Pediastrum simplex Meyen

17

            Pediastrum duplex Meyen

17

            Pediastrum biradiatum var. longicornutum

16

            Pediastrum tetras Ralfs

17
11

            Quadrigula closterioides

11

            Crucigenia tetrapedia (Kirch.) West et G.S.

14

17

            Crucigenia minima Brunnthaler
14

16

        Order II: Zygnematales

            Spirogyra sp. Link

3
7

            Closterium kutzingii f. sigmoides

22
26

            Closterium jenneri Ralfs

21

            Closterium parvulum Nag.

32

            Staurastrum pingue Meyen ex Ralfs

19
18

            Staurastrum cyclocanthum var.  ubacanthum vue apicale
21

13

            Staurodesmus dickiei var. maximus

14

            Cosmarium sp. Corda ex Ralfs

13

            Cosmarium scottii

18

            Cosmarium trachypleurum

12

            Cosmarium sinostegos var. obstusius

7

Total species diversity ()
24
26
23
63
41
49

Total species abundance
1169
738
2009
3490
3363
3767

Table 3: Pearson correlation coefficient matrix of water quality indices, total periphyton abundance, and rainfall from December 2012 to May 2013 at Ejirin, part of Epe Lagoon.

Parameters

Total abundance
Rainfall

Rainfall
0.745
1

Water temperature
0.744
0.855*

Transparency
−0.886*
−0.755

pH
0.797
0.65

Conductivity
0.115
0.701

TSS
−0.423
−0.652

TDS
0.836*
0.678

Salinity
0.403
−0.183

Reactive nitrate
−0.533
−0.375

Reactive phosphate
0.247
−0.319

Sulphate
0.707
0.374

Silicate
−0.870*
−0.53

Peri. chlorophyll a
−0.566
−0.007

BOD
−0.039
−0.398

COD
0.955**
0.587

DO
−0.597
−0.206

Correlation is significant at 0.05 level (2-tailed).

**Correlation is significant at 0.01 level (2-tailed).

Table 4: Biological indices parameters at Ejirin, part of Epe Lagoon, from December 2012 to May 2013.

Periphyton taxa
December
January
February
March
April
May

Total species diversity ()
24
26
23
63
41
49

Total abundance () cellsmL⁻¹
1169
738
2009
3490
3363
3767

Shannon-Wiener index ()
1.17
1.28
1.15
1.47
1.26
1.27

Margalef’s index ()
3.26
3.79
2.89
7.6
4.93
5.83

4. Discussion

The range value of the surface water temperature reported is notable for tropics. The highest water temperature observed in May could be a result of time of collection and heat capacity of water. The positive correlation that exists between rainfall and surface water temperature could explain the possible effect of precipitation on temperature. Nwankwo [28] reported that there are two main seasons in Nigeria: dry season (November–April) and wet season (May–October). The rainy season is ecologically more important in coastal waters and is bimodal in distribution. Floods caused by rainfall enrich the coastal environmental gradients (horizontal and vertical). With this seasonal pattern, it was observed that transparency, total dissolved solids, and total suspended solids increased with the onset of rainfall. The micronutrients concentration level increased as precipitation rate increased probably due to input from settlements and wetlands.

Odum [29] related pH levels to the amount of carbonate present in the water and often considered it an indicator of the aquatic chemical environment. The observed pH value (pH ≤ 6.6) falls within the range reported by Nwankwo and Akinsoji [30] for Epe Lagoon. The pH value could mainly be controlled by freshwater swamp exudates that regulate the acidity of the water body. Change in pH value has a profound effect on the conductivity level of the water. Furthermore, the high value of dissolved oxygen observed in January could be a result of combined photosynthetic activity of the microscopic plants, whereas the low value may be attributed to bacterial degradation of organic matter, which was observed at the onset of precipitation.

Hynes [31] reported that BOD values of 1-2 mg/L or less represent clean water, of 4–7 mg/L represent slightly polluted water, and of more than 8 mg/L represent severe pollution. Therefore based on the above criteria, the site was relatively clean except for December and March where levels of contamination were reported. The Shannon-Wiener index of diversity of 1–3 according to Wilh and Dorris [32] signifies moderately polluted water and above 3 signifies clean water situation. In this regard Shannon-Weiner index in December and March in periphyton community may point towards moderate pollution at this period.

However, the chlorophyll for periphyton community showed a rhythmic pattern with nutrient level mostly reactive nitrate. This may explain the importance of reactive nitrate to periphyton community. The periphyton abundance in the wet months differs significantly with that of dry months (; ). This could be a result of favourable conditions during this time that resulted in the multiplication of algal cell and additional input of pennate forms by the floods. The algal spectrum observed shows that diatoms were the dominant species in periphyton community.

Bowker and Denny [33] reported the limited growth of attached diatoms in the dry season and the rapid growth of macrophyte tissue. This may explain why more species were observed on macrophyte tissues in the wet months. Some of the algae that were common members of the plankton but were found in periphyton community were often trapped by the roots of the plant, like the centric diatoms. However, the centric diatoms found in the periphyton community were transit visitor caught up by the mesh formed of the water hyacinth roots.

The observations that diatoms dominate the periphyton community on water hyacinth confirm earlier reports [34, 35] that diatoms were more abundant in the algal spectrum of the Lagos Lagoon complex.

Round [36] observed the abundance of Eunotia sp. on Lemna roots whereas Bowker and Denny [33] reported the dominance of Achnanthes and Cocconeis sp. on the roots and leaves of Lemna, respectively. Cocconeis pediculus Ehr. and Achnanthidium sp. were only found in the periphyton community with Cocconeis occurring all through the months suggesting a strong coexistence. Cocconeis pediculus Ehr. occurred in a range of conditions from clean to moderately enriched to much enriched waters. Its presence and others (euglenoids; blue green algae; Nitzschia palea; Surirella sp.; Pinnularia sp.; Gomphonema parvulum; Mougeotia sp.; Spirogyra sp.; Trachelomonas affinis (Lemm.); T. ensifera Daday; T. gibberosa Playf.; Phormidium articulatum; Lyngbya intermedia; Cymbella ventricosa; Eunotia arcus; Surirella linearis; Asterionella formosa Hassall; N. acicularis; Amphora ovalis Kütz.; Ankistrodesmus falcatus; Scenedesmus armatus Chodat; and Closterium parvulum Nag.) may suggest pollution by organic materials.

The abundance of periphyton species on the water hyacinth may be given a second thought to enhance the aquaculture production in the area. A high species level for blue green algae and euglenoids in the periphyton community may reveal its suitability in monitoring environmental stress in coastal waters.

Conflict of Interests

The authors declare that there is no conflict of interests regarding the publication of this paper.

Acknowledgments

Special thanks are due to the staff of Marine Biology Laboratory, University of Lagos, and Professor D. I. Nwankwo for the help throughout the study period.

References

H. Schlorin, “The water hyacinth—a sensitive indicator for the environmental status of certain tropical water SCOPE/UNEP,” Sonderband, vol. 58, pp. 217–224, 1985.

A. B. N. Egborge, “Water hyacinth—biological museum,” in Proceedings of the International Workshop on Water Hyacinth, pp. 52–70, Lagos, Nigeria, August 1988.

J. W. Feminella and C. P. Hawkins, “Interactions between stream herbivores and periphyton: a quantitative analysis of past experiments,” Journal of the North American Benthological Society, vol. 14, no. 4, pp. 465–509, 1995.

G. E. Hutchinson, A Treatise on Limnology, vol. 3 of Limnologica Botany, John Wiley & Sons, New York, NY, USA, 1975.

J. Kalff, Limnology, Prentice Hall, Upper Saddle River, NJ, USA, 2002.

A. L. Behning, “Zur Erforschung der am Flussboden der Wolga lebenden Organismen,” Monographien der Biologischen Wolga-Station, vol. 1, no. 1, p. 398, 1924.

W. M. B. Cooke, “Colonisation of artificial bare areas by microorganisms,” The Botanical Review, vol. 22, no. 9, pp. 613–638, 1956.

R. G. Wetzel, “Attached algal-substrata interactions: fact or myth, and when and how?” in Periphyton of Freshwater Ecosystems, R. G. Wetzel, Ed., pp. 207–215, W. Junk Publishers, The Hague, The Netherlands, 1983.

Y. Vadeboncoeur, D. M. Lodge, and S. R. Carpenter, “Whole-lake fertilization effects on distribution of primary production between benthic and pelagic habitats,” Ecology, vol. 82, no. 4, pp. 1065–1077, 2001.

L. Liboriussen and E. Jeppesen, “Temporal dynamics in epipelic, pelagic and epiphytic algal production in a clear and a turbid shallow lake,” Freshwater Biology, vol. 48, no. 3, pp. 418–431, 2003.

R. E. Hecky and R. H. Hesslein, “Contributions of benthic algae to lake food webs as revealed by stable isotope analysis,” Journal of the North American Benthological Society, vol. 14, no. 4, pp. 631–653, 1995.

R. G. Wetzel, “Microcommunities and microgradients: linking nutrient regeneration, microbial mutualism, and high sustained aquatic primary production,” Netherlands Journal of Aquatic Ecology, vol. 27, no. 1, pp. 3–9, 1993.

M. J. Vander Zanden and Y. Vadeboncoeur, “Fishes as integrators of benthic and pelagic food webs in lakes,” Ecology, vol. 83, no. 8, pp. 2152–2161, 2002.

D. I. Nwankwo and A. Akinsoji, “Periphyton algae of a eutrophic creek and their possible use as indicator,” Nigeria Journal of Botany, vol. 1, pp. 47–54, 1998.

D. I. Nwankwo and A. O. Onitiri, “Periphyton community on submerged aquatic macrophytes (horn wort and bladderwort) in Epe Lagoon, Nigeria,” Journal of Agricultural Science and Technology, vol. 2, no. 2, pp. 135–141, 1992.

R. L. Lowe and Y. Pan, “Benthic algal communities as biological monitors,” in Algal Ecology: Freshwater Benthic Ecosystems, R. J. Stevenson, M. L. Bothwell, and R. L. Lowe, Eds., p. 753, Academic Press, San Diego, Calif, USA, 1996.

P. V. McCormick and R. J. Stevenson, “Periphyton as a tool for ecological assessment and management in the Florida Everglades,” Journal of Phycology, vol. 34, no. 5, pp. 726–733, 1998.

E. E. Gaiser, D. L. Childers, R. D. Jones, J. H. Richards, L. J. Scinto, and J. C. Trexler, “Periphyton responses to eutrophication in the Florida Everglades: cross-system patterns of structural and compositional change,” Limnology & Oceanography, vol. 51, no. 1, pp. 617–630, 2006.

P. S. Welch, Limnological Methods, McGraw-Hill, New York, NY, USA, 1948.

APHA, Standard Methods for the Examination of Water Waste Water, American Public and Health Association, American Water, Works Association and Water Environment Federation (WEF), 20th edition, 1998.

J. W. Foerster and H. E. Schlichting Jr., “Phyco-periphyton in an oligotrophic lake,” Transactions of the American Microscopical Society, vol. 84, no. 4, pp. 485–502, 1965.

J. B. Lackey, “The manipulation and counting of river plankton and changes in some organisms due to formalin preservation,” US Public Health Reports, vol. 53, no. 47, pp. 2080–2093, 1938.

G. M. Smith, The Fresh-Water Algae of the United States, McGraw-Hill, London, UK, 1950.

S. L. Vanlandingham, Guide to Identification and Environmental Requirements and Pollution Tolerance of Freshwater Blue-Green Algae (Cyanophyta), U.S. Environmental Protection Agency (EPA), 1982.

L. A. Whitford and G. H. Schmacher, A Manual of Freshwater Algae, Sparks Press, Raeigh, NC, USA, 1973.

B. J. F. Biggs and C. Kilroy, Stream Periphyton Monitoring Manual, NIWA, Christchurch, New Zealand, 2000.

A. E. Ogbeidu, Biostatistics: A Practical Approach to Research and Data Handling, Mindex Publishing Company Limited, Benin City, Nigeria, 2005.

D. I. Nwankwo, The Microalgae: Our Indispensable Allies in Aquatic Montoring and Biodiversity Sustainability, Inaugural Lecture Series, University of Lagos Press, 2004.

H. T. Odum, “Trophic structure and productivity of Silver Springs, Florida,” Ecological Monographs, vol. 27, pp. 55–112, 1959.

D. I. Nwankwo and A. Akinsoji, “Epiphyte community on water hyacinth Eichhornia crassipes (MART. SLOM) in coastal waters of southwestern Nigeria,” Archiv für Hydrobiologie, vol. 124, no. 4, pp. 501–511, 1992.

H. B. N. Hynes, The Biology of Polluted Waters, Liverpool Unibersity Press, Liverpool, UK, 1960.

J. Wilh and T. C. Dorris, “Biological parameters of water quality,” Bioscience, vol. 18, pp. 477–481, 1968.

D. W. Bowker and P. Denny, “The seasonal succession and distribution of epiphytic algae in the phyllosphere of Lemna minor L,” Archiv für Hydrobiologie, vol. 90, no. 1, pp. 39–55, 1980.

D. I. Nwankwo, Seasonal changes of phytoplankton of Lagos lagoon and the adjacent sea in relation to environmental factors [Ph.D. thesis], University of Lagos, Lagos, Nigeria, 1984.

D. I. Nwankwo, “Phytoplankton of a sewage disposal site in Lagos Lagoon, Nigeria,” The Journal of Biological Sciences, vol. 1, no. 2, pp. 89–96, 1986.

F. E. Round, The Biology of Algae, Edward Arnold, London, UK, 1965.