Limnology of Lake Bogakain, Bandarban, Bangladesh

Abstract

Bogakain, a natural high altitude (372 m) lake of Bangladesh has been limnologically investigated for the first time. At mid-point, the depth of the lake was measured 46.54 m and the Secchi visibility was 2.37 m. Water temperature from 1-10 m depth gradient showed slight stratification in the lake which varied from 27.0 - 22.4° C at 1.00 pm. pH at the different depths ranged from 7.8 - 9.1, conductivity from 75 - 80 μS/cm and TDS from 39 - 42 mg/l. Alkalinity ranged from 0.8 - 1.24 meq/l and DO from 0.61 - 11.39 mg/l. A total of 40 species of phytoplank-ton were recorded from the lake of which 21 belonged to Chlorophyceae followed by Cynaophyceae (5), Bacillariophyceae (4), Cryptophyceae (4), Euglenophyceae (3), Dinophyceae (2) and Chrysophyceae (1). Bloom by Synnechocystis salina Wisl was observed at 10 m depth. Water temperature correlated negatively and significantly with depth. Phytoplankton biomass as chl a correlated positively with phytoplankton density and water depth. The former variable showed negative correlation with pH and water temperature. Lake Bogakain is the deepest natural lake of Bangladesh and many of the previous concepts regarding the lake i.e., fishless, highly turbid water and it has got a thermal spring at the bottom was found invalid. Key words: Bogakain; Limnology; Macrophyte; Phytoplankton; Bangladesh DOI: 10.3329/bjb.v39i2.7301 Bangladesh J. Bot. 39(2): 153-159, 2010 (December)

Limnology of Lake Ashura, Dinajpur, Bangladesh

“…TDS, conductivity, alkalinity and NO 3 -N were higher than Bogakain while water temperature, pH and DO were closer in both the lakes. The high value of PO 4 -P was observed in lake Bogakain (Khondker et al 2010) compared to Lake Ashura. In lake Bogakain, the total density of phytoplankton varied from 686.62×10 3 -409381.73×10 3 ind/l (Khondker et al 2010).…”

“…The proportion (%) of recorded species of Cyanophyceae, Chlorophyceae and Cryptophyceae was lower in Lake Ashura than Lake Bogakain (Khondker et al 2010). Recorded species of Euglenophyceae in Bogakain is lower where diversity is highest in Lake Ashura.…”

“…A comparative analysis of physiographic, morphometric and limnological data for two natural lakes of Bangladesh namely, Lake Ashura (sampled in April, 2011) and Lake Bogakain (sampled in March, 2010, Khondker et al 2010) showed both the lakes are dissimilar in many aspects. The GPS of Lake Ashura is 25°25′-25°29′ N and 89°00′-89°05′ E and for Lake Bogakain it is 21°58′49″ N and 92°28′11″ E. Lake Ashura a shallow water body (Z max, 10 m, Alam and Begum 2005) low altitude (27 m) lake on the other hand, Bogakain is considered to be a high altitude (457-610 m) and deepest (Z max, 46.54 m, Khondker et al 2010) natural lake of Bangladesh.…”

“…There are only three true lakes namely, Rainkhyongkine, Bogakain and Ashuhila Beel or Ahshula Beel (Khan et al 1994, Rashid 1991. Islam and Uddin (1969) published an algological report on Lake Rainkyhongkine and recently, limnology of Lake Bogakain has been carried out by Khondker et al (2010). The exact location of the above mentioned two natural lakes of Bangladesh was known (Khan et al 1994, Rashid 1991.…”

A study on limnological aspects of Ramsagar lake in Dinajpur district

“…Highest value of dissolved oxygen (9.90 mg/l) in Ramsagar lake was recorded in the month of February and the lowest value (5.10 mg/l) in the month of May. Khondker et al (2010) found DO concentration varied between 0.61 to 11.39 mg/l at lake Bogakain, Bandarban, Bangladesh. It might be due to alteration of photosynthesis, abundance of phytoplankton, respiration by fish and other aquatic organisms of the lake.…”