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Evaluation of Bloom Dynamics and Seasonal Abundance of Cyanobacteria in Eutrophic Fish Culture Ponds at Three Different Regions of Bangladesh

Md. Ayenuddin Haque
Department of Fisheries, University of Rajshahi, Rajshahi, Bangladesh

Md. Abu Sayed Jewel
Department of Fisheries, University of Rajshahi, Rajshahi, Bangladesh

Priyangka Das
Department of Fisheries, University of Rajshahi, Rajshahi, Bangladesh

Mst. Samsad Khatun
Department of Fisheries, University of Rajshahi, Rajshahi, Bangladesh

Jakia Hasan
Department of Fisheries, University of Rajshahi, Rajshahi, Bangladesh

Sharmin Jahan
Department of Fisheries, University of Rajshahi, Rajshahi, Bangladesh

Abstract/ Executive Summary:

Seasonal cycle and bloom dynamics of cyanobacteria in relation to environmental parameters were studied in three areas- Godagari Upazila under Rajshahi district (GD ponds), Bogra city (BG ponds) and Singra upazila under Natore district (SG ponds) from September 2014 to August 2015. Standard methods were followed to analyze the water quality, sediment parameters and cyanobacterial cell density. Except temperature, mean values of all water quality parameters were found significantly different (P < 0.05) among the three study sites. 7 genera of cyanobacteria were identified whereas the highest density was recorded during September in all the studied ponds in order of BG ponds (130.36×10⁶ cells/l) > SG ponds (84.93×10⁶ cells/l) > GD ponds (58.74×10⁶ cells/l). Gradual decrease in cell density was observed from November to January, whereas the lowest density (12.25×10⁶ cells/l) was recorded at BG ponds in December, 2014. Higher values of soil organic matter, total nitrogen and pH were found to play significant role in determining higher cyanobacterial cell density at BG ponds compared to SG and GB ponds. The dominant species recorded in all the three studied regions was Microcystis sp.

Keywords: Bloom dynamics, Culture ponds, Cyanobacteria, Eutrophic fish culture, Seasonal abundance

Location: Rajshahi, Natore and Bogra district

Start Date: 00-09-2014

End Date: 00-08-2015

Program Area: Animal Health and Management

Commodity: Fish, Bacteria

Objectives:

This study is important for public health risk protection to ensure safe fish supply to be delivered to consumers.

Methodology:

The study was conducted from September 2014 to August 2015 in 9 fish culture ponds at three different locations of Rajshahi Division (three ponds from Godagari Upazila under Rajshahi district (GD ponds), three ponds from Shingra Upazila under Natore district (SG ponds) and three ponds from Bogra Sadar Upazila under Bogra district (BG). The Global Positioning System (GPS) coordinates of sampling ponds. All of the chosen ponds comprised of earth ponds and used for fish culture. Monitoring of the physico-chemical parameters was based on the procedure of APHA (1998). Surface water samples were collected once in a month between 10:00 and 11:00 h for analysis of various physico-chemical parameters using dark bottles. The water samples were chilled in ice and transferred to the laboratory at 4°C. Surface water temperature and transparency were measured using a Celsius thermometer and a black and white standard colour coded Secchi disc. Water pH was measured using an electronic pH meter (Jenwary, 3020). Nitrate -nitrogen (NO₃-N), phosphate-phosphorus (PO₄-P) concentrations were measured using the Hach Kit (DR/2010, a direct- reading spectrophotometer) with high range chemicals (Nitra Ver. 5 Nitrate Reagent Powder Pillows for 25 ml sample for NO₃-N and Phos. Ver. 3 Phosphate Reagent Powder Pillows for 25 ml sample for PO₄-P analysis). Dissolved oxygen (DO) and total alkalinity were measured by using a portable aquaculture kit (Model FF2, HACH, USA). Biological Oxygen Demand (BOD) was measured by using Hach BOD Trak meter (model No. 205) through measuring initial and final BOD after incubation in dark for five days. Soil quality in terms of organic matter (OM), total nitrogen (TN) and pH of the selected ponds were monitored at the start (September 2014) and at the end of the study period (August 2015). Soil samples were tested in the laboratory of Soil Resource Development Institute (SRDI), Shyampur, Rajshahi. Organic mat- ter and total nitrogen were calculated by the following formula: Organic Matter (%) = Organic Carbon (%) × 1.724 Total Nitrogen (%) = Organic Carbon (%) ÷ 12. Water samples were collected using phytoplankton net (25 µm mesh size) and fixed in 5% formalin on site. Identification of the cyanobacterial species were conducted under a phase contrast light microscope (Olympus CX21, Tokyo, Japan) with bright field and phase contrast illumination (Anagnostidis and Komarek 1985; Skulberg et al., 1993). Quantitative estimation of cyanobacteria was done on Sedgewick-Rafter counting chamber (S-R cell) by following the formula given by Stirling (1985), N = (A*1000*C)/V*F*L, where, N is the number cyanobacterial cells or unit per liter of original water, A is the total number of plankton counted, C is the volume of final concentrate of the sample in ml, V is the volume of a field, F is the number of the field counted, L is the volume of original water in liter. For the statistical analysis of data collected, one-way analysis of variance (ANOVA) was performed using the SPSS (Statistical Package for Social Science, evaluation version-20.0, IBM Corporation, Armonk, NY, USA). The mean values were also compared to see the significant difference through DMRT (Duncan Multiple Range Test) at 5% level of significance (Gomez and Gomez, 1984). The percentages and ratio data were analyzed using arcsine transformed data.

Source of Information: Archives of Agriculture and Environmental Science 4(1): 27-32 (2019)

Article Link (Online Journal): DOI: 10.26832/24566632.2019.040104

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

The present findings indicate that higher nutrient concentrations, alkaline pH with higher alkalinity of water create favorable condition for higher cell abundance of cyanobacteria in BG and SG ponds. However, lower cell density of cyanobacteria in GD ponds (Barind area) indicated low nutrient concentration, high water turbidity, acidic pH and lower alkalinity. Further study on noxious and harmful cyanobacteria and their toxin should be undertaken to find out the effect of cyanobacterial bloom on fish production in culture ponds.

Knowledge Management: Journal