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Abundance and Seasonal Variation of Zooplankton in Relation to Some Physico-chemical Factors in the Hamil Beel of Bangladesh

MD. MIJANUR RAHMAN
Department of Zoology, University of Dhaka, Dhaka-1000, Bangladesh

ANWARA BEGUM
Caritas Fisheries Program, 1/C, 1/A, Pallabi, Mirpur-12,Dhaka-1221, Bangladesh

MD. SHAHADAT ALI
Department of Zoology, University of Dhaka, Dhaka-1000, Bangladesh

Abstract/ Executive Summary:

Zooplankton abundance in the Hamil beel fluctuated distinctly and their populations varied from 460 to 2353 ind./l. The highest number was recorded in April followed in May. In November, the populations dropped to a minimum concentration (460 individual/l). In the zooplankton community, the leading group was rotifers (43.47%) followed by cladocerans (22.59%), naupli (10.71%), protozoans (9.19%), copepods (8.35%) and ostracods (7.16%). A total of 23 zooplankton genera was identified which composed of nine Rotifera, three Copepoda, three Cladocera, one Ostracoda and seven Protozoa. Water temperature, transparency, water depth, pH, dissolved oxygen (DO), free carbondioxide (CO₂), alkalinity, hardness, ammonia and nitrite were recorded in pertinent condition. The zooplankton abundance was significantly affected by the interaction with the physicochemical parameters. The rotifers correlated positively with DO and inversely correlated with the combined effects of free CO₂, alkalinity, ammonia, water depth and transparency. The copepod abundance decreased with the increase in transparency and water depth. The cladoceran showed a significant positive correlation with DO and inverse correlation with free CO₂ ammonia and hardness, respectively. The ostracods showed a significant positive correlation with pH and inverse correlation with ammonia.

Keywords: Beel, Physicochemical parameter, Zooplankton, Correlation co-efficient, Hamil beel

Location: Tangail district.

Start Date: 00-07-1998

End Date: 00-06-1999

Program Area: Conservation and Biodiversity

Commodity: Plankton

Objectives:

To find out a relationship between zooplankton abundances and physicochemical factors for the better management of beel fisheries.

Methodology:

The present study was conducted in the Hamil Beel, the closing confluence of the Jamuna and the Bangsai river at Madhupur of Tangail district covering an area of 16.02 ha. Geographically the beel is situated in the north-central part of Bangladesh and lies from 24°42'06" to 24°42'22" N and from 89°57'18" to 89°57'47" E. The study was conducted from July 1998 to June 1999. Samples for all physicochemical and biological parameters were collected every month between 10:00 a.m. and 12:00 a.m. from three stations of the beel. Water temperature was determined using a centigrade thermometer. The water transparency was measured by a Secchi disc (20 cm in diameter). The chemical parameters of the water were analyzed on the spot immediately after sampling according to the manual of HACH’s universal Aquaculture kits, Model No. FF-2, USA. For biological features, water samples were collected approximately 10 cm below the water surface level using a plankton net of mesh size 55 μm fixing with a conical flask of 50 ml at the narrow end, and preserved immediately in 5 % commercial formaldehide. The zooplanktons were identified with the help of a microscope (model Olympus CK-2, ULWCK-Japan). The quantitative counts of the zooplanktons were done using Sedgwick Rafter (S-R) counting cell and expressed as individual (ind.) per litre. The mean data were then calculated and analyzed using a window-based software.

Source of Information: Bangladesh J. Zool. 34(1): 7-12, 2006

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The study revealed that the Hamil beel was rich in zooplankton populations with pertinent physico-chemical variables during the study period between July 1998 and June 1999. The zooplankton abundance was affected significantly by the physico-chemical variables of the water of the beel. It is, therefore, suggested that the production of the Hamil beel ecosystem could be increased adopting a better management system.

Knowledge Management: Journal