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Microbial Species Diversity and Hydrological Effects on Their Occurrence at Karnaphuli River Estuary

Md. Wahidul Alam
Institute of Marine Sciences and Fisheries, University of Chittagong, Chittagong-4331, Bangladesh

Abstract/ Executive Summary:

Estuarine ecosystem of Bangladesh is presently polluted due to human interference. Present study was conducted at Karnaphuli River estuary to identify available microbial species with hydrological condition and effects of hydrology on their occurrence. Data were collected between March 2012 and June 2012 and analyzed through plate count method. Water temperature ranges from 26.5- 32? C; salinity 0.0 – 5.0‰; pH 7.5 – 7.9 and Dissolved Oxygen (DO) 2.28 – 2.91mg/l in water samples. Shannon diversity index, dominance index, evenness and richness were found 0.638892, 0.671192, 0.484817 and 0.570458 respectively. Salinity was found as main influential factor for occurrence of microbial species at Karnaphuli River estuary.

Keywords: Microbial, Diversity, Estuary,

Location: Chittagong district

Start Date: 00-03-2012

End Date: 00-06-2012

Program Area: Conservation and Biodiversity

Commodity: Aquatic animal

Objectives:

To estimate the E. coli concentration in water and soil of Karnaphuli River estuary and their relation with water parameters.

Methodology:

Description of the study area: The Karnaphuli is the principal river of Chittagong district of Bangladesh. It originates in the Lushai Hills of Mizoram (India), flows through Rangamati and the port city of Chittagong and discharges into the Bay of Bengal at latitude 22°12´N and longitude 91°47´E near Patenga. Geographically this estuary located between latitude 22°53´N and longitude 92°27´E and enters the districts of Chittagong from the north eastern side. The average channel depth of the basin at the river estuary is 8 meters, although the depth varies greatly in its upstream portion for strong current and sedimentation. Geologically, the entire catchment consists of a substratum of tertiary rocks covered with alluvial deposits. The overlying deposits show that it consists of successive layers of mud and sand. Hydrological parameters i.e. temperature, salinity, pH, dissolved oxygen (DO) fluctuate seasonally. Three sampling stations were selected for the present investigation with the basis of different types of pollution. First sampling station (St-1) located near Chaktai canal receives heavy discharges from different domestic and industrial sources to the estuary. Second sampling station (St-2) located between the St-1 and St-3 of the River where small city canal empties and carries industrial and city wastes. Third sampling station (St-3) located at the mouth of the estuary and receives discharges composed of different kinds of city wastes through a canal. The Karnaphuli is the principal river of Chittagong district of Bangladesh. It originates in the Lushai Hills of Mizoram (India), flows through Rangamati and the port city of Chittagong and discharges into the Bay of Bengal at latitude 22⁰12^/N and longitude 910°47/´E near Patenga. Geographically this estuary located between latitude 22°53´N and longitude 92°27´E and enters the districts of Chittagong from the north eastern side. The average channel depth of the basin at the river estuary is 8 meters, although the depth varies greatly in its upstream portion for strong current and sedimentation. Geologically, the entire catchment consists of a substratum of tertiary rocks covered with alluvial deposits. The overlying deposits show that it consists of successive layers of mud and sand . Hydrological parameters i.e. temperature, salinity, pH, dissolved oxygen (DO) fluctuate seasonally. Three sampling stations were selected for the present investigation with the basis of different types of pollution. First sampling station (St-1) located near Chaktai canal receives heavy discharges from different domestic and industrial sources to the estuary. Second sampling station (St-2) located between the St-1 and St-3 of the River where small city canal empties and carries industrial and city wastes. Third sampling station (St-3) located at the mouth of the estuary and receives discharges composed of different kinds of city wastes through a canal. Data collection and analysis: Present work was carried out between March and June 2012. Water samples were collected from three stations (st-1, st-2 and st-3) of the Karnaphuli River estuary during this study period. In situ measurement of water temperature was done by centigrade thermometer where water pH and salinity was measured by pen pH meter and refractometer (Name the models of instruments) respectively. DO concentration was measured in laboratory by following standard method. Collected water samples were preserved and microbial analysis was conducted at laboratory to identify the presence microbial load in water of the Karnaphuli estuary. Microbial load from water and soil sample was identified by standard plate count (SPC) techniques. Total plate count by pour plate techniques also done by without serial dilution in respect of the identification of health hazard bacteria in water. For enumeration of different bacteria different selective media i.e. EMB, Blood A, BGA, TGA and TCBS were used in order to enumerate Escherichia coli, Streptococci sp., Staphylococci sp., Salmonella sp., Vibrio cholerae etc. and thus triplicates plates were used for each sample. Then the average colonies formed in the plates were recorded which considered as total counts. As the microbial loads were very rare in water, so the author did the work without serial dilution in respect to identifying the growth of colonies in selective medium. One ml of water or diluted sediment samples (1g: 9 ml of distilled water) were transferred by sterile pipettes into petridish and the plates were poured with Levin’s Eosin Methylene Blue (EMB) Agar media for E. coli, Brilliant Green Agar (BGA) media for Salmonella spp., Blood Agar media for Streptococci spp., Tellurite Glycine Agar(TGA) media for Staphylococci spp. and Thiosulphate Citrate Bile Salt (TCBS) Agar media for Vibrio spp. and incubated at room temperature for 48 hours. Colonies having a green metallic sheen with dark centre were confirmed as Escherichia coli, colonies having a non-haemolytic with deep growth were confirmed as Streptococci spp., growth of colonies having a black surface were confirmed as Staphylococci spp., colonies having a pink opaque colour with surrounded by a bright red colour were confirmed as Salmonella spp. and colonies having a greenish centre were confirmed as Vibrio spp. present.

Source of Information: Agricultural Science Research Journal 3(6); pp. 158- 166, June 2013

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The presence or absence of Salmonella sp. and Vibrio cholerae were also observed in all the sampling stations during the study period. The presence of these pathogenic micro-organisms indicates truly polluted aquatic environments because of producing many serious diseases in animal and human body. In the present investigation, V. cholerae was found more than Salmonella sp.. Salmonella sp. was not found both in water and sediments at St-3 during the four months study period.

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