Journal of Applied Sciences & Environmental Management, Vol. 9, No. 1, 2005, pp. 79-84

Bacteriological Water Quality of Elechi Creek in Port Harcourt, Nigeria

OBIRE, O¹; TAMUNO, D C²; WEMEDO, S A³

^1,3 Department of Biological Sciences,  Rivers State University of Science and Technology, Nkpolu-Oroworukwo P.M.B. 5080, Port Harcourt, Nigeria Email: samwems@yahoo.com
² Production, Planning and Quality Control Unit, Port Harcourt Refining Company Ltd Eleme, Port Harcourt, Nigeria

Code Number: ja05014

ABSTRACT: The bacteriological quality of Elechi creek was investigated during a seven-month sampling period. Samples were collected from seven stations grouped into zones A, B and C. The study revealed uniformity in the range of temperatures (which ranged from 28^o to 32°C) in all the stations of the zones. The pH values obtained for all the stations ranged from 6.5 to 7.7 and were within the acceptable ranges for brackish water such as the study area. The BOD values for stations of zone B ranged from 3.92 to 8.80mg l^-1 while those of zones A and C ranged from 2.07 to 3.86 mgl^-1 and 1.43 to 3.46 mgl^-1 respectively. The reverse was the case for DO values, which were lower in stations of zones B than those of zones A and C. The results for oil and grease values for all the stations of the zones showed a range of 0.09 to 1.22 ppm which were far lower than the permissible limit for industrial effluent samples. The minimal values suggested absence of petroleum activities in the area. The results of the bacterial counts for the Elechi creek showed that total aerobic heterotrophic bacteria ranged from 0.12 x 10⁶ to 2.81 x 10⁶ cfuml,^-1, total coliform bacteria ranged from 0.06 x 10⁵ to 2.00 x 10⁵ cfuml^-1 and hydrocarbon-utilizing bacteria ranged from 2.0 x 10² to 10.0 x 10² cfulml^-1. The bacterial genera isolated from the Elechi creek included Aeromonas, Bacillus, Citrobacter, Corynebacterium, Pseudomonas, Enterobacter, Escherichia, Flavobacterium, Klebsiella, Micrococcus, Proteus, Staphylococcus, Enterococcus, and Vibrio species. Of the organisms isolated only Bacillus, Corynebacterium, Pseudomonas and Flavobacterium species occurred in all the stations of the zones while the others occurred in one or more stations and not in others station. The varying mean counts of bacteria and the occurrence of bacterial species the creek, brought to consideration, the possible influence and sources of contamination around each zone. The observed high coliform counts and the presence of Esherichia coli was sufficient to suspect the contamination of the water body with pathogenic bacteria; hence the  water is of low quality and should not be used  for human  consumption. The low counts of hydrocarbon-utilizing bacteria confirmed absence of a possible source of contamination of the creek by crude oil and its products. @JASEM

Bacteria are natural component of lakes, rivers, underground waters and streams. These bacteria are numerous and diverse assemblage of organisms (Hurst, 1997).  The immense numbers of these small organisms can have an enormous impact on processes that occur in aquatic ecosystem such as carbon, nitrogen and sulfur transformation. They can also have an impact on the quality of water by controlling the amount of oxygen and other elements in the water and by causing disease in aquatic organisms as well as in humans (Hurst, 1997). Furthermore, establishing the presence of bacteria in water bodies is important, as they have been identified as the major organisms, which initiate the breakdown of introduced organic wastes including hydrocarbons as well as metabolic intermediates. Indeed, monitoring water quality is essential to aquatic environmental management and protection (Zhang et al 1995)

Water sources could be perfectly clean in appearance, free from characteristics of odor and taste, and yet be contaminated (Lynch and Hobbie; 1988). It has been known since the middle ages that water contaminated with sewage could cause disease, but it wasn’t until 1885 that it was discovered that a particular type of bacteria called coliform bacteria are numerous and could always be detected in animal feces and sewage (Sloat and Zeil; 1991). Although coliform bacteria were not known to cause any illnesses, their presence in water was thought to be a predicator of other disease causing agents; and this findings established coliform bacteria as the first microbial indicator of sewage contamination (Lynch and Hobbie, 1988).

Microbiological analysis of water qualify has proved to be a very useful and significant method of biological assessment of even new or intermittent water pollution, which may be missed in a chemical sampling surveillance programme.(Manson,1989). Thus, the assessment of bacterial types  (heterotrophic and coliform) in a monitoring programme will provide protection to the greatest diversity of ecosystem.

The objectives of this study, therefore, are to estimate the numbers of coliform and heterotrophic bacteria as well as hydrocarbon utilizing bacteria in Elechi creek.   The basis of these investigations being to provide information on the bacterial community composition of the brackish water system which will be useful in predicting the degree of contamination of the water by sewage and hydrocarbon as well as determining the public health risks of the water to the inhabitants around the creek.

MATERIALS AND METHODS

Description of study area: The study area is the Elechi creek, close to Eagle Island, extending to the Iloubuchi street water bank in Diobu, Port Harcourt. The Eagle Island is located on the South-West of Port Harcourt and bounded on the North by the Rivers State University of Science and Technology in Nkpolu-Oroworukwo area of Diobu. The Elechi creek is a brackish water system influenced by tidal fluxes. It has mangrove vegetation. The configuration of the creek  basin which widens in some regions and narrows in some other areas restricts the tidal flow height close to the Nkpolu-Oroworukwo area of Diobu. The surrounding terrestrial environment is marked with various human activities such as timber sawing, waste disposal and frequent defecation on the banks of the creek. Pig breeding on a free-range basis, is also practiced in the area. During the construction of an access road from Iloabuchi to the Eagle Island, sand and dredged spoil deposited into one half of the creek inadvertently blocked the water flow in that half. The new road divided the creek into two halves. Consequently, water in one half was still free flowing, having its regular bi-directional tidal cycles, while the other half was without obvious tidal fluxes. During the study period, precipitation was minimal between January to February, 1996, considered as the dry season. While the raining season with relatively higher precipitation, include the period of March to July, 1996, when sampling ended.

Description of Sampling Stations: The study area was zoned into three viz; zones A, B, and C. The zoning of the study area was based on the peculiarities and features observed as well as the various activities being carried out at different points  along  the creek. A total of seven (7) sampling stations were designated from these zones. Sampling stations were chosen approximately 6 to 10 meters from the creek banks and about 40 to 60 meters apart from each other. Zone A has stations 1 and 2 covering the water body on both sides of the culvert on the road from Agip Oil Company to Eagle Island. Station 1 is located to the right side while station 2, is located to the left side of the culvert. Zone B contains stations 3, 4 and 5, covering the water body that situate to the left side of the access road when approaching the Iloabuchi street from the Eagle Island. Growth of mangrove vegetation, blooms of floating macrophytes of Pistia species and characterize the water body in this zone by growth of Nipa palm particularly in shallow areas near the banks. Logs of timber were pulled by manual labour between stations 4 and 5; and the banks of the access road near station 5 openly dumped waste materials. In zone C are stations 6 and 7 which covers the creek water on the right side of the access road when approaching Iloabuchi street from Eagle Island. Water flow in this zone is bi-directional to and from the Bonny  river. Wastes are dumped on the river  banks near station 7.

Collection of Water Samples: Water samples were collected from the different stations twice a month at two-week   intervals   for   7 months  (January to July, 1996).  The shoreline sampling method as described by Milne (1996), was employed. The collection of sample was accomplished by wading to slightly above knee depth and samples were taken approximately 20-30cm below the water surface. For microbiological analysis, 250ml volume seized sterilized sample bottles were used by holding the bottle at its base and deeping it downwards below the water surface, opened and allowed to fill up then corked while still under water (APHA, 1985). Two sets of water samples for dissolved oxygen (DO) determination were collected with sterile 250ml Winchester bottles. One set of the samples was fixed with 2ml each of Winkler I and Winkler II reagents. For other physico-chemical parameters water samples were collected with 500ml sterile glass bottles. Samples were stored in a portable ice-cooled box after collection at each station and appropriately labeled before transportation to the laboratory for analysis the same day.

Physico-Chemical Determination: The physico-chemical parameters determined for the creek water samples were temperature, pH, dissolved oxygen (DO) and biochemical oxygen demand (BOD).

The temperature of the samples was determined using a mercury thermometer. The pH of samples was determined immediately on arrival in the laboratory using a pH glass Kem-H- electrode meter (Model No. 210). The Winkler or Iodometric method as described by ASTM (1986) was used for the DO analysis from which BOD values were calculated. Oil and greese in water were determined after extraction with toulene by using spectrophotometer (Lovibond model).

Cultivation and enumeration of bacteria: Water samples were extracted under aseptic conditions using sterile 1ml pipettes and diluted serially up to x 10^-5 in physiological saline as suspending medium. After preliminary investigation, 0.1ml aliquots of 10^-3, 10^-2 and 10^-1 dilutions were inoculated onto appropriate growth medium for the cultivation of total heterotrophic bacteria, total coliform bacteria and hydrocarbon-utilizing bacteria respectively. The inoculation technique applied was the spread plate method, using a sterile bent glass rod.

The nutrient agar plates for cultivation of total aerobic heterotrophic bacteria were incubated at 28± 2°C while the MacConkey agar plates for the cultivation of total coliform bacteria were incubated at 37°C for 48h. The hydrocarbon-utilizing bacteria culture plates were incubated at 30°C for 5 days. All inoculations were made in duplicate and incubated along with corresponding uninoculated plates which served as controls.

At the end of each incubation period, colonies  which  developed were enumerated as total viable organisms. The relative abundance of coliform bacteria and hydrocarbon-utilizing bacteria, expressed as a percentage of the total viable heterotrophic bacteria were calculated. Discrete colonies were subcultured to obtain pure bacterial isolates for subsequent investigations.

Identification and occurrence of bacteria in Elechi creek: Pure bacterial isolates were identified on the basis of their cultural (colonial), morphological and physiological characteristics in accordance with methods described by Cruickshank et at., (1975). Identification was accomplished based on the scheme of Bergey’s Manual of Determinative Bacteriology (2001). The occurrence of the different types of bacteria in Elechi creek was thereafter recorded.

RESULTS AND DISCUSSION

The Elechi creek, like other surface water bodies, has been subjected to various contamination materials capable of initiating the impairment of the water quality. The range of the monthly average values of the physico-chemical parameters and bacterial counts for Elechi creek during the seven months study are as presented in Table 1.   The mean monthly values are shown in parenthesis.

There was uniformity in the temperature range in all the stations with values generally between 28°C to 32°C.  This uniformity was also observed in their   means, which showed slight variation of ± 1°C.  The high temperature observed in this study is believed to have been influenced by the intensity of sunlight and the general shallowness of the creek, which exposed the water body to the heat of the sun.  This is in support of the findings of Mulusky (1974). The pH range of 6.4 to 7.7 reported for Elechi creek could be considered as being within an acceptable range  for  a  brackish water system.   The pH of the creek in all the stations was neutral or near neutral.  Imevbore (1983) reported a pH range between 6.5 to 7.4 for brackish water bodies whereas Zheng et al., (1995) reported a slightly above neutral pH range  of  7.48 to 8.89.

The dissolved oxygen (DO) content in stations of zone B which was observed to deplete faster than DO in other zones could be attributed to the presence of degradable organic matter which resulted in a tendency to be more oxygen demanding as the BOD values in zone B also indicated. The lower BOD values in stations of zones A and C may have been influenced by tidal flows of water from Bonny river which effectively flushes and dilutes oxidizable organic matter out of these zones. This is made apparent considering the fact that organic matter from human and animal faecal mater imputed into water body of Elechi creek was a daily affair in all zones. Imevbore (1983) reported that the contamination of water with faeces, increases the biochemical oxygen demand because it contains mainly organic matter making oxygen less available to desirable organisms.

The population of total aerobic heterotrophic bacteria ranged from 0.12 x 10⁶ cfu ml^-1 to 2.81 x 10⁶ cfu ml^-1 in all the stations of the creek. The total coliform bacteria ranged from 0.08 x 10⁵ cfu ml^-1 to 2.00 x 10⁵ cfu ml^-1 and hydrocarbon-utilizing bacteria ranged from 2.0 x 10² cfu ml^-1 to 10.0 x 10⁵ cfu ml^-1 in all the stations.   The total aerobic heterotrophic bacteria counts and the total coliform bacteria counts were generally higher in all the stations of the creek whereas the total hydrocarbon – utilizing bacteria counts, in all the stations, were low.  The average counts for heterotrophic bacteria in all the stations ranged from 0.59 x 10⁶ to 1.57 x 10⁶ cfu ml^-1 for the total coliform bacteria, the average counts ranged from 0.43x10⁵ to 1.19 x 10⁵ cfu ml^-1 . The high counts of heterotrophic bacteria and coliform bacteria are attributed to the activities going on around the creek. Also, the high coliform bacteria counts are indication that disease-causing microorganisms may be present in the waters of the creek. Hence, thewater is not fit for drinking and for other domestic purposes. The relative percentage abundance of coliform bacteria ranged from 4.20% to 16.37% during the months of investigation and from 4.78% to 10.72% along the stations of the creek. While the relative abundance of hydrocarbon-utilizing bacteria ranged from 0.03% to 0.08% during the months of investigation and from 0.O37% to 0.074% along stations of the creek (Table 2).

As can be seen in table I and II, the bacteria counts in zone B were higher than the counts in the other zones; stations in zone B also had the highest counts of coliform bacteria even when expressed as a percentage of total heterotrophic bacteria [Fig. 1]. While the highest relative abundance of coliform bacteria were recorded in the month of March. However, the highest counts of total viable aerobic heterotrophic bacteria, total coliform bacteria and hydrocarbon-utilizing bacteria were as in figure 2, recorded in the months of January and March (dry season) and April (rainy season) respectively. This showed that different physiological groups of bacteria respond differently to different seasons.

The range of concentration of oil and grease in stations of Elechi creek as recorded in table 1 is generally low. Such minimal values were not surprising as there were no petroleum or oil-related activities in the surrounding environment. High levels of oil and grease raise great concern especially in an aquatic environment because of its possible adverse effect on the biotic community. Values less than 10ppm as reported in this study falls within permissible limit in industrial effluent samples (FEPA, 1991). The abence of oil in creek waters accounted to low counts of hydrocarbon-utilizing bacteria.

The bacterial species isolated in the stations of Elechi creek are shown in table III. Of the fourteen species isolated, only Bacillus, Corynebacterium, Pseudomonas and Flavobacterium species occurred in all the stations of the three zones. The other species occurred in some stations and not in the other stations. Aeromonas, Enterococcus, Klebsiella, Micrococcus and Vibrio species were not isolated from zone C. The relationship between environmental factors and natural microbial populations are fairly complex and could lead to variations in bacteria numbers and types. Hence, varying numbers of bacteria could be obtained in different sampling stations or same stations at different occasions. Bacterial types isolated in this investigation varied in the different sampling stations (Table 3). Atlas (1988) reported that the population of any aquatic system is to a large extent influenced by the water body. Hollaway et al., (1980), stated that establishing the presence of bacteria in water bodies is important, as they have been identified as the major organisms which initiate the breakdown of introduced wastes including hydrocarbons to various metabolic intermediates.

In conclusion, the present investigation revealed that certain physio-chemical parameters and bacteria were present in relatively high concentrations. Although, there were zonal as well as station variations in the physico-chemical concentrations and, bacteria counts and types. The observed high coliform counts and presence of Escherichia coli was sufficient to suspect that the water body was also contaminated with pathogenic bacteria. The low counts of hydrocarbon-utilizing bacteria indicated absence of crude oil contamination of the Elechi creek from a possible source. Generally speaking, the water of the Elechi creek is of very low quality and should not be used for human consumption.

REFERENCES

 
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