International Journal of Marine Science2016, Vol.6, No.50, 1-9
1
Research Article Open Access
Identification and Mapping of Ocean Biological Deserts Using Satellite Data
Mini Raman
1
, Rahul Rajan
1
, Ajai
2,
1. Space Applications Centre, Ahmedabad-380015, India
2. ES, CSIR, Space Applications Centre, Ahmedabad- 380015, India
Corresponding author email
International Journal of Marine Science
2016, Vol.6, No.50 doi
Received: 18Sep. 2016
Accepted: 06Dec. 2016
Published: 09Dec. 2016
This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.
Preferred citation for this article
:
Raman M., Rajan R., and Ajai, 2016, Identification and Mapping of Ocean Biological Deserts Using Satellite Data, International Journal of Marine Science,
6(50):1-9(doi
Abstract
The ability of oceans to sequester large amounts of atmospheric CO
2
through the biological pump has generated
considerable interest in formulating strategies towards mitigating the impact of climate change. One such mitigation strategy is the
artificial fertilisation of oceanic waters characterised by very low phytoplankton biomass. Regions of ocean that contain low
phytoplankton biomass or chlorophyll-concentrations are called as ‘Ocean Biological Deserts’. A primary requirement for conducting
fertilisation experiments is the identification of regions that are uniformly low in chlorophyll concentration without any seasonal or
interannual variations. This communication reports the identification of uniformly low chlorophyll regions (ocean biological deserts)
in the Arabian Sea and Bay of Bengal using satellite derived ocean colour variables that can be considered suitable for artificial
enrichment.
Keywords
Ocean colour; Chlorophyll-a; Ocean biological deserts; Arabian Sea; Bay of Bengal; Artificial fertilisation
1Introduction
Over the past 150 years, human civilisation’s weight on the essential life-supporting services of the Earth System
has grown fivefold. Human activities such as fossil fuel emissions, biomass burning and land use changes have
profoundly impacted the global cycles of many greenhouse gases especially the global carbon cycle. The present
carbon dioxide levels are higher than the levels experienced on the planet for over last 400, 000 years, paving the
way for a rapid climate warming by several degrees in the next few decades (McCarthy and James, 2009). Based
on General Circulation Model outputs for different scenarios of increased atmospheric carbon dioxide, the average
global temperature is projected to increase by 1.8 to 4.0
0
C by the end of 21
st
century (IPCC 2007). Attempts to
limit the future growth of atmospheric carbon dioxide concentration will involve major and potentially costly
modifications in energy and technology policy. Assessment of the climatic impacts of increasing atmospheric CO
2
levels and its mitigation requires an understanding of long- term storage changes in all key carbon reservoirs
(atmosphere, oceans and the terrestrial biosphere).
Oceans play a significant role in influencing Earth’s weather and climate. Through a complex system of winds and
currents, the oceans and atmosphere work together to distribute enormous quantities of heat and to regulate global
temperature (Trenberth and Soloman, 1994).Of all the greenhouse gases, carbon dioxide is the most important
because of its links with anthropogenic activities. Ocean’s carbon inventory is approximately 40 giga tons. This is
approximately sixty five times larger than the CO
2
inventory of the atmosphere and ~ 20 times larger than the
amount of carbon tied up in terrestrial biosphere (Trenberth and Soloman, 1994). A number of physical, chemical
and biological processes govern the transport of carbon in the ocean from the surface waters to the deep waters
and sediments of the ocean floor as well as its cycling among various organic and inorganic forms. The transport
of atmospheric carbon dioxide into the ocean’s interior is governed by two pumps, the solubility pump and the
biological pump. The uptake of carbon through photosynthesis by phytoplankton and its export to ocean interior
and sediments constitute the biological pump. Phytoplankton, a group of microscopic, free-floating autotrophic
organisms are the main primary producers of the upper ocean forming the base of food chain and providing
trophic support for oceanic life. Through the process of photosynthesis, phytoplankton converts inorganic matter
