Impact of salinity and pH on phytoplankton communities in a tropical freshwater system: An investigation with pigment analysis by HPLC

Abstract

An in vitro study was carried out to understand the effects of salinity shock and variation in pH on phytoplankton communities in a tropical freshwater system of the Godavari River (a major peninsular river in India). The distributions of, and variations in, phytoplankton communities were assessed by quantitative determination of their class specific marker pigments, using HPLC. Subtle changes in salinity of the freshwater by one practical salinity unit (PSU) completely removed green algae from the system and allowed the cyanobacteria to come into dominance. The cyanobacteria were found to tolerate higher osmotic stress until the salinity reached a PSU of 16. The higher salinity tolerance range of the cyanobacteria was attributed to the enhanced synthesis of zeaxanthin as protective xanthophylls against the osmotic stress. However, the effects of changing pH were not as dramatic as salinity where the green algae and the cyanobacteria from the same freshwater system showed a considerable acclimation towards the fluctuating pH. These findings are environmentally relevant to understand the likely impact of salt water intrusion and pH variation on phytoplankton communities in a tropical freshwater system.

First report of paralytic shellfish poisoning (PSP) caused by Alexandrium tamiyavanichii in Kuantan Port, Pahang, East Coast of Malaysia

“…Changes in environmental conditions have been known to affect the physiology of phytoplankton species, thus determining the rapid growth and massive abundance of phytoplankton (Macedo et al 2001;Chakraborty et al 2011). In this study, the physico-chemical parameters were similar during the PSP events but fluctuated slightly more after the events.…”

“…; Chakraborty et al . ). In this study, the physico‐chemical parameters were similar during the PSP events but fluctuated slightly more after the events.…”

Acclimation of the Marine Diatom Pseudo‐nitzschia australis to Different Salinity Conditions: Effects on Growth, Photosynthetic Activity, and Domoic Acid Content1

“…High salinity conditions may trigger the formation of intracellular reactive oxygen species (ROS; Rout and Shaw , Chakraborty et al. ), which can be critical since the generation of ROS may be irreversible and cell destructive. As a part of the antioxidative mechanism, diatoms are known to be able to increase the production of xanthophylls including zeaxanthin, another photoprotective mechanism, in order to avoid the ROS formation (Pelah et al.…”

Intra‐annual variation of phytoplankton community responses to factorial N, P, and CO2 enrichment in a temperate mesotrophic lake

“…To enrich nitrogen, 3.401 g of KNO 3 was added to each mesocosm while controls each received 2.508 g of KCl to account for the addition of potassium (K) as it could potentially act as a limiting nutrient (Talling, ). Note that the concentration of Cl added in the controls represents approximately 0.75mg/L (or 0.04 mmol/L), which is unlikely to significantly affect freshwater phytoplankton (Chakraborty, Acharyya, Raghunadh Babu, & Bandyopadhyay, ; Reynoso & de Gamboa, ), nor their zooplanktonic predators (Gonçalves, Castro, Pardal, & Gonçalves, ; Martínez‐Jerónimo & Martínez‐Jerónimo, ). To enrich phosphorus while maintaining a stable pH, 0.069 g of H 2 KPO 4 and 0.088 g of HK 2 PO 4 were added to each mesocosm while controls each received 0.113 g KCl.…”