Phytoplankton composition and the occurrence of cyanobacterial bloom in Lake Maninjau, Indonesia

Abstract

Algae blooms have been recorded in Lake Maninjau in November 2000, October 2011 and recently on April 2018. These blooms were indicated by green scum formation on the lake surface with a very high chlorophyll-a concentration, as high as > 100 µg-L. We determined the characteristics of phytoplankton composition and abundance including environmental conditions during cyanobacterial blooms and non-cyanobacterial blooms in Lake Maninjau. During cyanobacterial blooms, phytoplankton were dominated by Microcystis aeruginosa with a maximum abundance of 24,320 x 103 individual L-1 (94.4 % of the total assemblage). While during the non-blooming period, cyanobacteria species were more diverse, represented by Cylindrospermopsis raciborskii, Anabaea affinis, Aphanizomeon sp, Planktolyngbya sp. and Chroococcus sp. Diatom (Synedra ulna) generally occurred in all conditions, however, desmids (green algae) disappeared during cyanobacteria blooms. It is highlighted that the occurrence of Microcystis blooms can be related to total phosphorous dynamics in the lake.

Trophic Status and Phytoplankton Community Structure of Four Small Lakes in Ciliwung Watershed, Indonesia

“…A Low TN/TP ratio is often found in the cyanobacteria bloom condition. In Lake Maninjau, the bloom of Microcystis aeruginosa occurred in low the TN: TP ratio (4.7) [32]. A low TN: TP ratio in Lake Sunter and Lake Cincin indicate high phosphorus concentration and nitrogen become the limiting factor for phytoplankton growth.…”

“…Most observed lakes have a high chlorophyll-a concentration, with the highest concentration of 431 µgL-1 was recorded in Lake Sunter. Cyanobacteria bloom in Lake Maninjau was characterized by high chlorophyll-a concentration (> 100 µgL -1 ) in 2011 and (97.475 µgL -1 ) in 2018 [32]. WHO has defined Chlorophyll-a of 10 μgL -1 as a threshold effect for drinking water and chlorophyll-a of 50 µgL -1 as a threshold effect for recreational water use [33].…”

“…Differentiation of percentage abundance of phytoplankton composition among observed lakes could be influenced by hydrological, physical and chemical factors such as temperature, light intensity, nutrient, and pH [34]. In Lake Maninjau, Indonesia Microcystis aeruginosa bloom was recorded in a higher water column stability period and low TN: TP ratio [32].…”

Physical-Chemical Characteristic and Trophic Status of Some Small Lakes in Ciliwung Watershed, West Java Indonesia

“…TN and TP ratio is most often used as an indicator of cyanobacteria bloom and which one of the nutrients has to be controlled in order to reduce algae bloom. In Lake Maninjau bloom of Microcystis aeruginosa was occurred in the higher total phosphorus with the TN:TP ratio value 4.7 (Sulastri et al, 2019). A low TN: TP ratio in Lake Cincin indicate a surplus of phosphorus and nitrogen as limiting factor for phytoplankton growth.…”

“…Mostly chlorophyll-a concentration showed a high in observed lakes which is the highest concentration (431 µgL -1 ) recorded in Lake Sunter. In lake Maninjau, chlorophyll-a concentration reached 97.475 µgL -1 during Microystis aeruginasa bloom in April 2018 (Sulastri et al, 2019). WHO has defined Chlorophyll-a of 10 μgL -1 as a threshold effect for drinking water and chlorophyll-a of 50 µgL -1 as a threshold effect for recreational water use (Ho and Michalak, 2015).…”