Influence of environmental parameters on toxic cyanobacterial bloom occurrence in a Lake of Bangladesh

Abstract

Increased nutrients have led cyanobacteria to become dominant in many ponds, lakes and reservoirs in many countries of the world. The occurrence and abundance of cyanobacterial population were monitored in a lake (known as Ishakha Lake) at Bangladesh Agricultural University campus, Mymensingh, Bangladesh. The hydrographic parameters such as water temperature, pH, chlorophyll a and nutrients (NO 3 -N and PO 4 -P) were recorded to find out their relationship with the cyanobacterial bloom formation. During the study period five species of cyanobacteria namely, Microcystis aeruginosa Kütz., M. wesenbergii Kom., M. botrys Teli., M. viridis (A. Br.) Lemm. and Anabaena circinalis Rabenh., were identified and among them M. aeruginosa was the dominant species during the bloom period. At the peak period of bloom, the highest cell density of M. aeruginosa was 1550 9 10 3 cells ml -1 which comprised 97.45 % among the blue-green algae and 96.84 % to the total phytoplankton. The initiation and persistence of natural bloom of cyanobacteria, especially Microcystis spp. was found to be controlled by relatively high temperature ([25.00°C) and nutrients, especially high NO 3 -N (3.80 mg l -1 ) concentration. Temperature and NO 3 -N showed positive correlation with cyanobacterial cells abundance which were r = 0.62 and r = 0.92. Therefore, it could be said that temperature and NO 3 -N made a favorable circumstance to form cyanobacterial bloom in as Ishakha Lake. concentration of MCs 37,460.00 pg ml -1 at the peak period of bloom.

Satellite-Based Monitoring of the Algal Communities of Aras Dam Reservoir: Meteorological Dependence Analysis and the Footprint of COVID-19 Pandemic Lockdown on the Eutrophication Status

“…In addition to meteorological factors, the water trophic status has been introduced as an important environmental factor affecting cyanobacterial communities. Affan et al ( 2016 ) emphasized that natural blooms of Microcystis spp. are typically controlled by trophic condition and nutrient concentrations of water.…”

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“…14 The inhibition of growth of other microalgae may be due to the toxin produced by the Microcystis. 41 Microcystis aeruginosa inhibited the growth of several species in laboratory cultures and apparently reduced the production of other algae in three Missouri ponds. 42 Microcystis played a dominant role to create bloom.…”

Seasonal dynamics of zooplankton in a eutrophic fish pond of Bangladesh in relation to environmental factors

“…Then 2-3 drops were removed from the middle of the sample and placed on a glass slide. 21 Taxonomic determination of zooplankton was performed with a phase-contrast microscope (Olympus, Japan) at 40 X magnification, with a bright field and phase contrast illumination on living materials and samples preserved with formaldehyde. Zooplankton identification was done up to the genus and species level where possible following the standard descriptions of Conway et al 22 Altaff 23 and Yousif Al-Yamani et al 24 The counting of zooplankton cells was done in a 1ml Sedgewick-Rafter counting chamber following the sedimentation method of Utermöhl.…”