Role of ancient algae in building a healthy global marine ecosystem

Role of ancient algae in building a healthy global marine ecosystem

 

By-Mohammad Faiyaz Anwar, Scientist at Vigyan Prasar Science Portal

CHANDIGARH–A study of a microscopic ancient marine algae
(Coccolithophores) led by the National Centre for Polar and Ocean
Research (NCPOR) has found that there is a decrease in the
concentration of oceanic calcium carbonate (CaCO3) in the Southern
Indian ocean. This decrease in CaCO3 is attributed to the increase in
the concentration of another single-celled algae known as diatoms.
This, in turn, will affect the growth and skeleton structure of
coccolithophores, with potential significance for the world ocean
ecosystem.
Coccolithophores are single-celled algae living in the
upper layers of the world’s oceans. They have been playing a key role
in marine ecosystems and the global carbon cycle for millions of
years. Coccolithophores calcify marine phytoplankton that produces up
to 40 per cent of open ocean calcium carbonate and responsible for 20
per cent of the global net marine primary productivity.
These build exoskeletons from individual CaCO3 plates
consisting of chalk and seashells building the tiny plates on their
exterior. Though carbon dioxide is produced during the formation of
these plates, coccolithophores help in removing it from the atmosphere
and ocean by consuming it during photosynthesis. At equilibrium,
coccolithophores absorb more carbon dioxide than they produce, which
is beneficial for the ocean ecosystem.
NCPOR, the National Institute of Oceanography (NIO),
and the Goa University revealed that abundance and diversity
enrichment of coccolithophores in the southern Indian Ocean is highly
dependent on time and influenced by various environmental factors such
as silicate concentrations, calcium carbonate concentration, diatom
abundance, light intensity and availability of macro and possibly
micronutrient concentrations.
The research team’s analysis revealed that the
reduction of coccolithophore diversity in the early summer and late
summer periods is due to an increase in the presence of diatom algae,
which occurs after sea ice breakdown with climate change and ocean
acidification, and increases the silicate concentration in the waters
of the Southern Ocean. The scientists also analyzed the maximum
coccolithophore diversity during mid-summer in the Subtropical Zone
(STZ) and Sub-Antarctic Zone (SAZ), which is controlled by elevated
silicate, low temperature, and low salinity conditions.
Scientists found that the biogeographic boundaries of
coccolithophores in the southern Indian Ocean are highly variable,
controlled by environmental factors in early and mid-austral summer,
and grazing pressure in late austral summer. Also, physical forcing
may play an important role in the transport of coccoliths and
coccospheres at high latitudes, indicating that the southward
extension of coccolithophores is important and may occur for short
periods during hot summer.
The results of the study point to climate change as a
major reason for the altered coccolithophore calcification rate.
Different environmental factors and the ability of the species to
adapt to those environmental changes would ultimately determine the
future coccolithophore calcite production. These investigations are
important for future intervention to bring positive changes in the
marine ecosystem and the global carbon cycle.
Led by Shramik M. Patil, the research team comprised
Sathish Rahul Mohan and Sahina Gazi, of NCPOR, Ministry of Earth
Sciences, Goa, and Suhas S. Shetye of NIO, and Pallavi Choudhari of
the Goa University. The research paper has been published in the
Journal of Deep-Sea Research Part II.

By YS.Rana:
yadavindras@gmail.com

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SK Vyas

SK Vyas

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