Journal of Applied Sciences and Environmental Management World Bank assisted National Agricultural Research Project (NARP) - University of Port Harcourt ISSN: 1119-8362 Vol. 10, Num. 1, 2006, pp. 43-45

Journal of Applied Sciences & Environmental Management, Vol. 10, No. 1, March, 2006, pp. 43-45

Physico-chemical conditions and distribution of phytoplankton in the Brass River, Nigeria

*^aNYANANYO, BL; ^bOKEKE, CU; ^cMENSAH, SI

^a,bDepartment of Plant Science and Biotechnology, University of Port Harcourt, Choba, P. M. B. 5323, Port Harcourt, Rivers State, Nigeria.

^cDepartment of Plant Science and Biotechnology, Abia State Univeristy, Uturu

Code Number: ja06007

ABSTRACT: The physiology, physico-chemical conditions and distribution of phytoplankton in the Brass River, Nigeria has been assessed. The data on physico-chemical conditions revealed a near constant water surface conditions for all the stations sampled. The relative abundance of phytoplankton population of the Brass River system revealed the presence of the following marine phytoplankton families Bacillariophyceae (Bidulphia auria, M. mobiliencesis, B. sinsensis, Skeletonema costatum), Chlorophyceae(Halosphaera ividis), and Dinophyceae (Ceeratium sectum). @JASEM

Phytoplankton are small free floating algae which, which contribute to the total suspended plant and animal cells of both fresh and salt water and are the basis of food chain in these environment. The Brass River is a tributary of the Nun River in the Niger Delta area of Nigeria.  There is a paucity of literature on the surface waters of the Brass River system especially on the relative abundance of phytoplankton population (Biney et al., 1994). The Brass River is one of the important tributaries of the River Nun (Nyananyo, 1999). Studies on water bodies in the West African sub region points to the fact that a lot of research is needed on them (Lawson, 1960; Green, 1962 and Imevbore, 1965). The present investigation is aimed at increasing the data on phytoplankton in the Brass River and consequently to West African water bodies.

MATERIALS AND METHODS

 Description of study area: The Brass River is one of the tributaries of the River Nun in the central cartographic Niger Delta (Nyananyo, 1999, 2002). The cartographic Niger Delta is Africa’s largest delta covering some 7,000 square kilometers. About one third of this area is made up of wetlands, and it contains the largest mangrove forest in the world, 5,400-6,000 square kilometres (Afolabi, 1998; Nyananyo, 1999, 2002). The mangrove swamps which are also vegetated tidal flats are sandwiched between the outer barrier island complex and the older sands of the Benin formation (Oyegun, 1999) The evolution of these tidal flats are primarily through the process of repeated bifurcation of the Niger-Benue river system which breaks up into tributaries at Ebu ito (Nyananyo, 1999, 2002). A reticulate drainage pattern characterizes the tidal flats of the Brass River. This drainage pattern is due mainly to the higher elevation at the edges than at the centre of the flats (Allen, 1965). The vegetated tidal flats are composed of three elements:

1. the main feeding channels which derive from fresh water sources en route to the sea.
2. smaller channels which connect them together and
3. elevated tidal flats exposed only at low tide  (Oyegun, 1999).

Sample collection and analyses: Six sampling stations were selected within the study area along lines at right angles to the shore.

Physico-chemical parameters: At each station, water samples were taken at the surface and at maximum depth. These were immediately stored in an ice chest. Temperature, depth, pH, and transparency were measured in situ. Temperature and pH were measured using field thermometers and the SISS TECHN WERKSTA model D812 WELHEN field pH meters respectively. Transparency and depth of the water at the various stations were measured as follows: - 

Transparency: This determination was by the use of a white secci disc to which was attached a calibrated twine. This device was dropped into the river gradually at specified points, and the point at which the white disc was not seen was taken as the limit of light penetrability. This distance was recorded.

Water depth: a weight was attached to a calibrated twine, and dropped into the river at specified points. The point on the twine at which the attached weight made contact with the substratum was taken as the depth of the station in question. This was recorded.     

Phytoplankton identification: To assess the composition of primary producer populations each station was sampled for phytoplanktons. Water samples were collected 20 – 30 cm below the surface using a 1 litre Van Dorn water sampler closed by means of a weight messenger dropped along the cable to trip the closing mechanism. A sub sample of 250ml was removed and treated with 5ml Lugol’s solution (60 g KI + 40g I₂ crystals, d/w) to stain and preserve the specimens for identification. This 250 ml sub sample was concentrated by allowing the sample to stand for 24 hours. A 1ml sub sample was pitted out at the end of the period into a Sedgenick-Rafter counting chamber. Microscopic identification were made of all sub samples and recorded. 

RESULTS AND DISCUSSION

The results obtained from the study are presented in Tables 1 – 5. The temperature variation (Table 1) in the area is not wide, and this could be beneficial to the phytoplanktons within the area. The wide variations in water depth (Table 2) is as a result of selective artisanal fishing activities carried out by the fishermen living in this area, whereas the pH and transparency  measurements (Tables 3 and 4) show relatively turbid and acidic levels at stations 1, 4, 5 and 6.

Table 1. Water Temperature (^oC) at the various stations

Table 2: Water depth at the various stations (CM)

These areas coincidentally are within the vicinity of the “AGIP” oil company export terminal in Twon-Brass and “SHELL” oil company NEMBE CREEK flow station. It is submitted therefore that effluents from these oil industrial installations could have contributed to the relatively turbid and acidic levels of the water at stations 1, 4 whereas 5 and 6 is not so (Tables 3 and 4). The record of twelve species of phytoplankton distributed amongst three families (Table 5) is note worthy. Phytoplanktons are small free floating algae which contribute to the total suspended plant and animal cells of both fresh and salt water and are the basis of the food chain in these environments (Hill, Popp and Grove, 1980).

Table 3:  Water pH at the various stations

Conclusions: The results of this study shows that further investigations will be beneficial and the effluent from the oil installations should be properly treated before they are emptied into the Brass River system to ensure that the food chain which eventually lead up to the Homo sapiens is not disrupted as this will be catastrophic to the very existence of Homo sapiens.     

Table 4. Transparency  of  the water at the various stations (CM)

Table 5: Marine Phytoplanktons recorded in the study

 Acknowledgement: Grant from the University of Port Harcourt Senate-NUC to the first author for this research is acknowledged.  

REFERENCES

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• Oyegun CU (1999), Climate, relief and drainage. In: Alagoa, EJ (ed.) The Land and people of Bayelsa State: Central Niger Delta. Onyoma Research Publications, Nembe. p31

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