Shifting phytoplankton diversity at Sunderbans is an early sign of climate change

Researchers in India has found a low abundance of a temperature sensitive phytoplankton Ceratium symmetricum at the estuaries and offshore of Sunderbans Biosphere Reserve. The change, which is triggered by the rise in the temperature of the surface water can be an early sign of climate change affecting the mangrove ecosystem of Sunderbans, says the study.

Ceratium symmetricum
Photo Courtsey: JOTT

Phytoplankton are minute photosynthetic aquatic organism floating on the water surface as a green discoloration of the water surface. Being primary producers, they are the foundation of a marine food web by offering food to fishes and other aquatic organisms.

The study which is the first one to examine the phytoplankton diversity in the Indian side of the Sunderbans, has assessed the presence of genus Ceratium Schrank in connection with physicochemical parameters such as Sea Surface Temperature (SST) in the estuaries of the Hooghly and Ichamati-Raymongal Rivers on the western parts of the Sunderbans.

Phytoplankton as bio-indicators

Phytoplanktons are known for their bio-indicator capabilities since any slight change in water temperature or the environment make big difference in their abundance. Members of Ceratium genus are especially known for their sensitivity towards temperature.

The research team has identified 5 species of phytoplankton from the genus - Ceratium trichoceros, Ceratium symmetricum, Ceratium fusus, Ceratium tripos and Ceratium furca- from the water samples. Among them, Ceratium symmetricum was not reported from the area earlier and was found in low abundance. According to earlier studies, low abundance of certain Ceratium species in the surface water during warm period is a sign of change.

To find out a possible cause for it, the researchers have studied the fluctuation pattern of the Sea Surface Temperature with the help of satellite imagery form 2003 to 2009. The data showed that the winter SST has been showing a rising trend in the area, possibly due to climate change.

  

Future Impact

 The lower abundance of Ceratium symmetricum and the rising trend in the winter SST are indicators of climate change affecting Sunderbans, says the study which is published in the latest issue of Journal of Threatened Taxa. It also points out that a further rise in the SST in the area may wipe the Ceratium symmetricum away from the Indian part of the Sunderbans, making it the first organism to take the toll of the climate change and the resulting temperature rise.

Anirban Akhand, Anirban Mukhopadhyay, Pranabes Sanyal and Sugata Hazra from the School of Oceanographic Studies, Jadavpur University, Sourav Maity, Indian National Centre for Ocean Information Services (INCOIS), Indrani Das, Department of Botany, Midnapore College took part in the study.

Do you think Climate Change is a hoax? Have your say here.