Phytoplankton in relation to water quality of Tanguar Haor ecosystem, Bangladesh: 2. Watch tower station

Abstract

Phytoplankton biomass in relation to some environmental and nutritional parameters at Watch Tower Station of Tanguar and Rauar Station has been studied. Since the Haor is a Ramsar Site, it is a globally important aquatic ecosystem. In the present investigation, the structure of the phytoplankton and the water quality factors were worked out and the data were compared Rauar Station with having the same ecosystem. Though weaker, a difference among alkalinity, total dissolved solids (TDS), conductivity, dissolved oxygen (DO), Secchi disc transparency, soluble reactive phosphorous (SRP), soluble reactive silicate (SRS), NO3-N, NH4+, chlorophyll-a and phytoplankton population density was found between the Watch Tower and the Rauar Station of Tanguar Haor. The mean values of the aforsaid parameters were found to some extent higher in the Watch Tower Station. The Watch Tower Station was deeper and perennial, where the depth of water varied from 3.0 - 9.5 m annually with a mean of 6.72 m. In the studied station, air and water temperature varied from 22.6 - 30.6 and 22.7 - 30.3°C, respectively. Water transparency ranged from 2.08 - 3.0 m. From December to March the pH remained 8.1-9.7 and alkalinity from 0.73 - 1.35 meq/l. However, from April to September these two parameters ranged from 7.5 - 7.7 and 0.33 - 1.35 meq/l, respectively. Dissolved oxygen (DO) and free CO2 concentration ranged from 2.5 - 6.09 and 0.084 - 0.087 mg/l, respectively. During April to September the Chlorophyll-a value ranged from 5.5 - 7.5 μg/l while the range of SRP was 24.23 - 30.05 μg/l during the same period. At the latter part of the study year i.e., during the dry period (December to March) those two parameters were relatively low in concentration. In April a high concentration of NH4+ (1380 μg/l) was reported from the haor, at other times this parameter ranged from 690 - 820 μg/l. The NO3-N ranged from 0.25 - 0.75 mg/l. High density of phytoplankton population (2690 ind./l) was reported at the time of high concentration of SRP (30.05 μg/l ) of the haor water. The chlorophyll-a value (7.5 μg/l) was also highest at that time. So, it could be said that SRP concentration in Tanguar haor has been playing a vital role in regulating the standing crop of phytoplankton. To find the variation on a spatial scale, the data of the present investigation were compared with another study station of the haor namely, Rauar Station. No significant difference was observed among the concentrations of different parameters. However, a slight increasing trend in the concentrations of DO, alkalinity, SRP, NO3-N, SRS, NH4+ and total phytoplankton density was observed in the Watch Tower Station compared to Rauar Station. Watch Tower Station is also relatively deeper with an improved light climate as it had been revealed by the mean value of the Secchi depth. The water quality of Tanguar Haor has been classified as mesotrophic.
 Dhaka Univ. J. Biol. Sci. 29(1): 9-18, 2020 (January)

Phytoplankton flora of Tanguar haor ecosystem in Bangladesh: Cyanophyta, Pyrrhophyta, Chrysophyta and Euglenophyta

“…In planktonic population, Dinobryon has been recorded from a hilly water body of Maulvi bazar and Kaptai Lake, though these studies do not reveal any size of the population Khair 1978, Islam andIrfanullah 2005). Recently, Bhuiyan et al (2019) based on the phytoplankton biomass as chlorophyll a, Sechhi depth and the concentration of soluble reactive phosphorus designated Tanguar Haor as mesotrophic which is also supported by the results of the present investigation. Floristic work in the Haor ecosystems of Bangladesh is poor.…”

“…Samples for the present investigation were collected in between the years 2017 and 2018 from two distinct sampling stations of Tanguar Haor, namelyWatch Tower and Rauar Stations (Bhuiyan et al , 2019. On each occasion and at each sampling station, one hundred liter of pelagic water of the Haor was passed through a plankton net (mesh width 25 µm) and the concentrate accumulated in the bucket of the net was transferred to a glass vial.…”

“…Since then there has been no other information on the floristic composition of phytoplankton from the haor ecosystems of Bangladesh. Recently, Bhuiyan et al ( , 2019 studied the ecosystem of Tanguar Haor of Sunamganj District in respect to the water quality factors and their interrelationships with the phytoplankton biomass as chlorophyll a and cell density. From the trophic standpoint, Tanguar Haor has been characterized as mesotrophic (Bhuiyan et al 2019).…”

“…Recently, Bhuiyan et al ( , 2019 studied the ecosystem of Tanguar Haor of Sunamganj District in respect to the water quality factors and their interrelationships with the phytoplankton biomass as chlorophyll a and cell density. From the trophic standpoint, Tanguar Haor has been characterized as mesotrophic (Bhuiyan et al 2019). Although, information on wetland trees and fishes are available for Tanguar Haor, there is no information on the qualitative aspects of phytoplankton flora of the Haor.…”

Phytoplankton flora of Tanguar Haor ecosystem of Bangladesh: Chlorophyta

“…Though, Islam and Paul (1978) studied the aquatic macrophytes and phytoplankton flora of the Haor Hakaluki of Maulvi Bazar District, there exists few information on the floristic composition of phytoplankton for Tanguar Haor of Sunamganj District. Recently, Bhuiyan et al (2019) published the phytoplankton flora of Tanguar Haor ecosystem covering the species of phytoplankton belonging to the divisions Cyanophyta, Pyrrhophyta, Chrysophyta and Euglenophyta.…”