Convener, MECOS 09 For and on behalf of the Marine Biological Association of India
Abstract
Marine ecosystems contain several unique qualities that set them apart from other
ecosystems. Of the 89 elements occurring in nature, the presence of 80 has been
confirmed in seawater. It is perhaps true that the remaining 9 elements are also present,
but in concentrations too small to be detected. This wide range of substances dissolved
in seawater has placed the marine organisms in a more advantageous position than
their freshwater counterparts. These elements provide the essential materials required
for the synthesis of all the basic nourishments of the body including the skeletal
support of marine animals. In the terrestrial ecosystems, the physical boundaries are
well marked and environmental variabilities are rather wide. The terrestrial organisms
and ecosystems have developed internal mechanisms to cope up with variabilities.
In contrast, in the marine ecosystems, the physical variability is small and extends
over very long time scales due to the large thermal capacity of the oceans and the
long periods of exchange between deep and near shore waters. Consequently, the
marine ecosystems are more vulnerable to large-scale environmental changes because
they do not have the internal adaptability inherent in the terrestrial systems
