A Study on Phytoplanktonic Composition in Dadin-Kowa Dam, Gombe State, Nigeria

ISAH Zainab¹*, ABUBAKAR K. A.², UMAR D. M.¹ and HASSAN S. K.¹

Greener Journal of Biological Sciences, vol. 8, no. 3, pp. 042-050, July 2018

¹Department of Biological Sciences, Gombe State University, Nigeria

²Departement of Zoology Modibbo Adama University of  Technology  (MAUTECH) Yola, Nigeria

INTRODUCTION                

Aquatic environment is the most diverse ecosystem in the world. The first life originated in the water and first organisms were also aquatic where water was the principle external as well as internal medium for organisms. Thus water is the most vital factor for the existence of all living organisms. Water covers about 71% of the earth of which more than 95% exists in the oceans; an average depth of 3800 meter (12,500 feet), the volume being about 1370 x 10⁶ km³. A much less amount of water is contained in rivers (0.00015%) and lakes (0.01%) which comprise the most valuable fresh water resources (Tideman, 2000).

               The plankton community is a mixed group of tiny plants and animals floating, drifting or feebly swimming in the water mass(Hensen, 1997). Plankton is diverse group of organisms that live in the water column and cannot swim against a current. The name plankton is derived from plantos, meaning errant, and by extension “wanderer” or drifter. Some forms are capable of independent – movement and can swim hundreds of meters vertically in a single day; their horizontal position is primarily determined by the surrounding currents (Hensen,1997).

Phytoplankton

The photosynthetic component of the plankton is known as the phytoplankton. It consists of phytoplankton classes includes: Bacillariophyceae, Cyanophyceae and Dinophyceae.  Phytoplankton is microscopic single celled aquatic plants forming the prime component in the food chain of an aquatic ecosystem. The fertility of sea is determined by its bio productivity. Phytoplankton production contributes about 95% of total production in the     marine environment (Mani, 1993).

            The complex plankton community comprises primary producers, herbivores, carnivores, dentrivores    and   decomposer organisms. Thus, prokaryotes, plants and animals are the plankton.  Primary producers are the basis for the planktonic food web and food energy in other aquatic communities (Porter,1976).

Aim of Study: This study is aimed at providing information on the phytoplankton  population in Dadin-kowa Dam, by identify the species, composition and distribution of phytoplankton in each sampling site.- Evaluate monthly variations in the abundance and distribution of phytoplankton species among  sampling sites.- Determine the physico-chemical characteristics of the water as it influence phytoplankton distribution in the Dam.

Study area: The research work was carried out in Dadin-kowa Dam, located at Yamaltu Deba local Government area of Gombe State in Northeast of Nigeria.

Its lies between latitude 10⁰ 19^’ 10^”N and longitude 11⁰  28^’ 54^” E with a capacity of 800 million cubic meters of water and a total surface area of 300 km².The average annual temperature is about 24⁰c and mean annual rainfall of 850mm, relative humidity range from 15-80%. The area experiences two seasons, the wet (April-October) and dry season (November-March), with Sudan savanna vegetation.(Mike,2010).

Sample collection: Samples were collected from three different locations: Station A, where fishing activities occurs, Station B, where anthropogenic activities take place and Station C, where Irrigation activities occur. Samples were collected from each station using plankton net of mesh size 55µm by hauling the sampler horizontally for five meters according to the method of Anene (2003). The resultant concentrated plankton samples were then   transferred to plastic containers, and preserve in 4% formalin solution and Logols iodine solution according to the method of Boney (1983) and Anene (2003) in the field. Samples were collected once a month for six months (July- December 2014).

Determination of Physico-Chemical Parameters

Some water quality parameters monitored during period of the study where, Water temperature was measured using thermometer (Model;YXI 550) by dropping the thermometer into the plastic sample bottle. The reading was recorded insitu in the field.

The transparency was measured using black-white Secchi disc. The measurement was done by lowering the disc into the water gradually until it disappeared from sight, then it was removed gently till it appeared. The average depth of its disappearance and reappearance was noted.

Multiphotometer dissolved oxygen analyzer (model;YXI 550) was used to determine the dissolved oxygen. This was done by collecting water sample in a cylindrical bottle and putting the tip of the analyzer to take the reading.

The conductivity of the water was taken using conductivity meter (model;YSI 63) and the reading was recorded.

The pH was determined using pH-meter (model;YSI 63) by inserting the tip soft of the meter in sampling bottle containing water. The corresponding pH values were recorded.

Sample Analysis: Phytoplankton samples were concentrated to 30ml volume before the analysis was done. Sample was homogenized by inverting the container or bottle few times, with a wide mouthed pipette, 1ml of the plankton sub-sample was withdrawn from the field samples, and placed on a sedge-wick rafter-counting chamber with cover slip and observed by direct microscopy. keys provided by standard works of Botes,2001,Emi and Catlin,2007, APHA 1998 and  various authors were used for species identifications. Counts were made in triplicates and their averages were taken and expressed as cell/ml of water.

Statistical Analysis: The number of organisms per liter of water was calculated from the following    relationship.

Number of organisms  =  organisms per ml of concentrate  volume of conc

                        per liter of water                                   volume of dam water filtered

The volume of the Dam water filtered by the sampler was calculated using the equation:

V=,

Where =3.1415,  r  = diameter of the net sampler

L = length haul by net in meters (Robert, 2003).ANOVA was used to analized the data.

RESULTS

The physico-chemical parameters recorded in Dadin-kowa Dam indicating various range of the parameters; The air temperature range from 26°C to 38ᵒC and water temperature range from 28^ᵒC to 31.9°C(Table 1).The lowest mean water pH value of 7.5 was recorded in Site A and highest pH value of 8.9 was recorded at Site B&C during the sampling periods(Table1).The lowest mean transparency value of 0.06m was recorded at Site A&B and the highest value of 0.16m at Site B &C. The lowest mean dissolved oxygen value of 1.7mg/l was recorded at Site C and highest value of 3.9mg/l was recorded at site A(Table 1).The conductivity of the water body recorded its lowest mean water value of 81µs/cm at site A &B and the highest conductivity value of 100µs/cm was recorded at site A during the sampling periods(Table 1).

A total number of three phytoplankton taxa were identified at Site B and C and four taxa at site A with ten plankton species identified at both sites. A total of phytoplankton crop was 69475 cell/l recorded in the Month of July in all the site samples. Four Phytoplankton taxa were identified at site B and C and three taxa at site A, with ten phytoplankton species recorded in August. The number of cells recorded per liter of water sample is 92,105cell/l. Three phytoplankton taxa were identified at site A and C and  four taxa at site B with fourteen species recorded in the Month of September with 89,475cell/l.

 Four phytoplankton taxa identified per each site, with ten species and a total number of cells per liter of water sampled for October recorded as 72,105cell/l. In November, four phytoplankton taxa were identified each at site A and B and three taxa at site C with 13 species recorded. The number of cells recorded per liter of water sample was 61,580cell/l. During the Month of December, three phytoplankton taxa were recorded per site with a total number of eight species and the total phytoplankton crop of 44,317cells/l.

Table 1:  Measurement of Physico-Chemical Parameters Sampled in Dadin-kowa Dam from July to December 2014

Table 2: Phytoplankton taxa and species composition which recorded at different stations during July, 2014

Table 3: Phytoplankton taxa and species composition recorded at different stations during, August, 2014

Table 4: Phytoplankton taxa and species composition  recorded at different stations during September, 2014

Table 5: Phytoplankton taxa and species composition which recorded at different stations during October, 2014

Table 6: Phytoplankton taxa and species composition recorded at different stations during November, 2014

Table 7: Phytoplankton taxa and species composition recorded at different stations during December, 2014

Table 8: Mean percentage distributions of phytoplankton classes at the different sites during the study period, 2014.

DISCUSSION

A total number of twenty two species of phytoplankton, were identified during the study period. Out of these 10 were Chlorophyceae, 6 Bacillariophyceae,4 Myxophyceae and 2 Chrysophyceae. This is similar with the finding of Mohamed et al 2009 and Anagoet al 2011 who reported phytoplankton and zooplankton taxa in a study of phytoplankton diversity on Koil Coastal waters India and Awba Reservoir Ibadan Nigeria.Dike and Adedolapo (2012) reported that Bacillariophyceae (53.25%), Cyanophyceae (21.25%), Chlorophyceae (10.33%), Chrysophyceae (4.84%), Pyrrophyceae (4.57%), Xanthophyceae (3.39%), and Euglenophyceae (2.42%) in studies of seasonal dynamics in plankton abundance and diversity of freshwater body in Nigeria. As compared to the findings of present study, Bacillariophyceae (38.1%), Chlorophyceae (35.4%), Myxophyceae(25.3%), and Chrysophyceae (1.22%).Their distributions might be due to availability of nutrients in water. This  also agreed  with the findings of Koloet al( 2010),Jerling and Wooldridge(1995) who recorded that the zooplankton was dominated by Copepoda and phytoplankton with Bacillariophyceae (diatoms) which were more abundant after flood.

The Bacillariophyceae and Chlorophyceae had the highest mean population in all the three stations during the rainy season. This could be attributed to availability of more nutrients, which favour their growth during that period as a result of agricultural and irrigation activities and nutrients might have washed up into the water by runoff. In term of planktonic populations between the months of study. High population of phytoplankton were observed during the month of August (92,105 cell/L and the minimum recorded in November and December (44,317 cell/L) Mohamed et al.(2009) reported this results with a maximum of137,800 cell/L in the Month of May and a minimum  of 76,150 cell/L. This could be attributed to the changes in temperature, pH, nutrients levels  during the period.

The rainy periods recorded the highest phytoplankton abundance than the dry season. The result of this study also agrees with findings of Khan and Ejike (1984) who observed greater plankton population density in the rainy season as compared to the dry season.

The Month of August recorded the highest plankton value of 21.9% as compare to the least value of December as 11.4%.The abundance of plankton in the rainy season might be attributed to the availability of more nutrients, suitable temperature range, conductivity, pH and dissolved oxygen that allow plankton to reproduce. This findings agrees with the work of Jerling and Wooldridge(1995) in Sunday River, South Africa who recorded high abundance of both phytoplankton and zooplankton during rainy periods. This also agrees with  the findings of  Rabi’u et al.(2007) in Kusalli Resevoir, Kano who revealed that phytoplankton was generally more numerous during rainy season than in dry season and dominated by Chlorophyceae (36.25 %) and Cladoceran in zooplankton. 

Spatial distribution of planktons were very abundant in site A (37.8%) than site B (33.9%) and site C appeared to have the least value of (28.3%).Analysis of variance showed significance of abundance between the sites.The variation between the sites might be attributed to the different activities such as fishing, bathing, washing, irrigation, watering ground for animals and so on occurring in the sites, which might have been contributed to the abundance of plankton with one site harbouring the plankton than others. This agrees with the findings of Adeyemi- Ale et al.,2014, in study of physico-chemical properties and plankton diversity in Osere, Ilorin with sites and one harbouring the plankton than the rest. There were great significance differences of plankton abundance between the sites.

Relationship between physico-chemical parameters and plankton abundance

Temperature is an important factor that influences primary production in water (Lewis, 2000). Also, Wetzel (1983) observed that increasing of the temperature led to increasing the rate of molting and brooding. The temperature of air increased from 26ᵒC to 38°C while that of water temperature ranged from 28ᵒC to 31.9ᵒC. This study shown gradual increase in temperature during the sampling periods and might be a driving factor responsible for plankton abundance in the water shown by its significant difference in the period of study. Therefore water temperature increases the rate of reproduction in water bodies. Dissolved oxygen; this is a crucial factor that help in the survival of aquatic  organisms. The dissolved oxygen concentrations ranged from 1.7 mg/L to 3.9mg/L and thus, the concentrations were within the acceptable range. McNeely et al., (1979) reported that natural surface water has dissolved oxygen less than 10mg/L. Low dissolved oxygen affect  the growth of many aquatic life, helps in metabolic activities(Charles,2003),therefore, adequate dissolved oxygen is necessary element to all processes of life. The relationship between temperature and oxygen is that, as the temperature increases, the oxygen level decreases, in other word, cold water hold more oxygen than warm water. Conductivity (µs/cm), referred to the ability of liquid to transmit heat, electrical charges or sound from one area to another. Conductivity ranged from 81 to 100µs/cm and ANOVA showed significant difference between the Months of study. The mean value was 91.2 µs/cm this showed that the conductivity level was intermediate. Conductivity levels below 50 are considered as low, those between 50 – 600 are medium and above 600 µs/cm are high (Adeleke,1982).

Transparency is referred to the clarity of water or the measure of how clear the water is. The transparency ranged from 0.06m to 0.16m.This range indicated that the water was not very turbid, therefore, all the stations received relatively equal amount of light from the sun, and this might be responsible for the presence of plankton in all the stations. The relationship between conductivity and transparency is that, an increased in transparency, increases suspended materials in water and subsequently, decreases conductivity which results in a decrease in light penetration and phytoplankton growth. pH; this is the measure of hydrogen ions concentration. The pH range from 7.5 to 8.9 which was within the normal range for aquatic life, therefore, this indicated that various anthropogenic activities inputs did not alter the ambient pH. High water pH can affect reproduction, cause death to many aquatic organisms, inability to dispose metabolic wastes and low pH can cause shock and sudden increase in number of some plankton species (LCAA).

In conclusion, about twenty two species of phytoplankton were identified. In terms of phytoplankton population, the bacillariophyceae was dominated with 38.1%from the total of phytoplankton classes. Phytoplankton abundance were influenced by seasons and by sites and species composition was significantly influenced by seasons not sites. Thus, plankton abundance and distribution were closely associated with environmental conditions. Hence, the present study provides the baseline information on plankton population which could be useful for further assessment of the water.

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