A TAXONOMIC ACCOUNT ON THE PHYTOPLANKTON OF A POND RECEIVING TEXTILE INDUSTRIAL EFFLUENTS

Phytoplankton from four stations of a large pond receiving effluents from two textile industries have been investigated. A total of 69 taxa were identified out of which 48 belonged to Chlorophyceae followed by 17 to Cyanophyceae. One species from each of Chrysophyceae, Xanthophyceae, Cryptophyceae and Dinophyceae were also recorded. Oscillatoria limnetica Lemm., Anabaena circinalis Rabenh. ex Born. et Flah., Nostoc commune Vaucher ex Born. et Flah. Ankistrodesmus falcatus var. mirabilis (West & West) Lemm. and Scendesmus spp. were found dominant in all the stations. Introduction The effluents, discharged in rivers, ponds, lakes, etc., are as varied as the human activities which produce them. According to Hynes and Pentelow (1978) six categories of effluents exist, namely (i) inert suspensions, (ii) poisons, (iii) inorganic reducing agents, (iv) oils, (v) organic residues, and (vi) hot water. The degree of pollution can often be measured most easily by a biological analysis in which phytoplankton are important indicators. For the assessment of water quality biological indicators are better than chemical and physical features (Round 1985). In India, aspects of biology of industrial wastewater have been studied by Mohan and Kumar (1990) and Baliarsingh et al. (1991). In Bangladesh, a number of research works have been carried out on phytoplankton from a range of habitats and localities (Islam and Begum 1970, 1987, Islam and Irfanullah 2005a, b, c, 2006, Khondker et al. 2007a, b). Phytoplankton from organically polluted ponds were worked out by Islam and Khatun (1966), Islam and Nahar (1967), and Khondker et al. (1990), but there exists very little information on qualitative aspects of phytoplankton from the polluted habitats contaminated by industrial wastes. The present work has therefore been undertaken to study qualitative account of phytoplankton (excluding members of Bacillariophyceae and Euglenophyceae) from a pond receiving wastewater from two textile industries in Dhaka. Materials and Methods The investigation was carried out in a large permanent pond near Deilla, Demra, Dhaka during 1990-1991. The pond is an open drainage type having one inlet and is regularly charged with effluent wastewater released from the nearby textile and dyeing E-mail: botany@univdhaka.edu


Introduction
The effluents, discharged in rivers, ponds, lakes, etc., are as varied as the human activities which produce them.According to Hynes and Pentelow (1978) six categories of effluents exist, namely (i) inert suspensions, (ii) poisons, (iii) inorganic reducing agents, (iv) oils, (v) organic residues, and (vi) hot water.The degree of pollution can often be measured most easily by a biological analysis in which phytoplankton are important indicators.For the assessment of water quality biological indicators are better than chemical and physical features (Round 1985).In India, aspects of biology of industrial wastewater have been studied by Mohan and Kumar (1990) and Baliarsingh et al. (1991).
In Bangladesh, a number of research works have been carried out on phytoplankton from a range of habitats and localities (Islam and Begum 1970, 1987, Islam and Irfanullah 2005a, b, c, 2006, Khondker et al. 2007a, b).Phytoplankton from organically polluted ponds were worked out by Islam and Khatun (1966), Islam and Nahar (1967), and Khondker et al. (1990), but there exists very little information on qualitative aspects of phytoplankton from the polluted habitats contaminated by industrial wastes.The present work has therefore been undertaken to study qualitative account of phytoplankton (excluding members of Bacillariophyceae and Euglenophyceae) from a pond receiving wastewater from two textile industries in Dhaka.

Materials and Methods
The investigation was carried out in a large permanent pond near Deilla, Demra, Dhaka during 1990-1991.The pond is an open drainage type having one inlet and is regularly charged with effluent wastewater released from the nearby textile and dyeing industries.Four stations or sampling points, namely S-1, S-2, S-3 and S-4, were selected in the pond for sampling.
Samples were collected at fortnight intervals at a depth of about 25 cm below the surface of water.A rafter was used for this purpose.Air and water temperatures were recorded by a mercury (centigrade) thermometer.pH and redox potential (RP) were measured by CD-300 digital portable pH meter with the help of the electrode (PHM-HBA-220U, 24:760/6).Dissolved oxygen (DO) and free carbon dioxide were analyzed according to APHA (1976).The bicarbonate alkalinity was measured after Gerrath and Denny (1979).

Results and Discussion
Table 1 shows annual ranges of some physicochemical variables from the studied pond.Except S-1 no significant variation was observed in case of air and water temperatures.Annual maximum water temperature recorded at this station was about 6-7°C higher compared to the maximum temperature recorded in other stations.Might be this station was receiving some hot water discharge from the industries.A minimum pH value has been recorded at this station and S-4.Anoxia was observed in all the stations.Carbon dioxide was occasionally undetectable at S-1 and S-3.Similarly bicarbonate alkalinity was also undetectable at different times in all the stations.A total of 69 phytoplankton taxa were recorded from the pond.The taxa which were found to be dominant were also previously reported to be dominant in different aquatic habitats in Bangladesh.The taxa belonged to the classes Cyanophyceae, Chlorophyceae, Chrysophyceae, Xanthophyceae, Cryptophyceae and Dinophyceae.A brief account on each taxon has been provided below including its abundance in station(s).