Ecological Science

Marine food web affected by phytoplankton

The biomass significantly alters the food web and ocean’s ability to absorb atmospheric carbon

March 14, 2021
The Scitech

Schematic diagram showing heterogeneous controlling factor phytoplankton biomass and various diet preferences of zooplankton with respective to regional influences along Indian coast

Scientists at the National Center for Coastal Research (NCCR) have explored how changes in primary producers of phytoplankton are affecting the secondary producers of phytoplankton biomass in the complex coastal ecosystem of the Northern Hemisphere between the Arabian Sea and the Bay of Bengal in the eastern part of the country. According to NCCR scientists, the baseline observations noted through the present study will help to understand the trend and type of food web operating along the Indian coastline and accordingly the role of food preference of zooplankton on fishery yield could be understood.

In addition to the monsoonal runoff and regional processes, the phytoplankton biomass along the Indian coast may be influenced by anthropogenic inputs through river discharge. Nutrients such as nitrogen, phosphorous and silicate play a key role in phytoplankton abundance, growth and metabolism. However, higher concentrations of nitrate were found in the East coast of India (ECI) than in the West coast of India (WCI). Despite higher nutrients are found along the ECI due to discharge of major rivers, threefold higher phytoplankton biomass has been observed along the WCI than the ECI due to high suspended solid concentrations (SSC). On the other hand, rivers also bring terrestrial organic matter along with SSC to the coastal region that may be supporting zooplankton carbon needs in the ECI.

The authors of the present study said that phytoplankton biomass growth is minimum along the ECI due to higher load of SSC and removal of nitrate is also minimum. However, zooplankton population was supported more by phytoplankton biomass along the WCI whereas terrestrial organic matter brought by river in the ECI. Researchers believe that due to the ongoing climate change, world fisheries are economically suffering a lot. As per recent records on fisheries, the southwest coast provides 31% of the fishery yields and 26% are from the southeast coast. The modification of river discharge (mainly reduction) may reduce terrestrial organic matter inputs to the coastal regions that may lead to a significant decline in zooplankton biomass and therefore fisheries population. An estimate suggests that global warming could cut the value of world fishery catches from 41 billion dollars a year to about 17 billion dollars a year by 2050 with East Asia and the Pacific suffering the greatest losses.

Led by Manuri D. B., the research team comprised of Chandrasekaran M., Perumal M., and Mallavarapu R.M of NCCR, NIOT Campus, Chennai, Ministry of Earth Sciences. The study is published in Environmental Science and Pollution Research.

(Source: India Science Wire)