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Abstract:
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Plankton community, drawn from a vary wide variety of animal phyla, formed
the basic food supply of marine life and indicators of water mass. The term
meroplankton generally referred to that portion of the zooplankton which is
transient in nature, remaining rest of their lives in the nektonic or benthic
environment. This group was selected for intensive studies, considering the role
of meroplankton in the economy of the sea and the scarcity of literature on them
from the Indian Ocean. The preser .udy besides providing information regarding
the fixation and preservation !e _ iniques and biochemical aspects of tropical
meroplankton, also consolidates information regarding their zoogeography in the
Indian Ocean region, with a view to amplifying the limited information available
from this area.
The distribution studies are based on the collections made during the International
Indian Ocean Expedition (1960-65), whereas the material for preservation and
biochemical studies was collected from the coastal waters during 1968-1978.
Salient features:- 2% of formaldehyde buffered with 2% borax, added to the
plankton in the ratio of 9:1 was found the best fixative. On fixation the plankton
underwent shrinkage due to loss of 15 to 87% water. Addition of antioxidants
prevented colour fading. Narcotization by different specific reagents prior to
fixation reduced distortions due to violent reaction and improved morphological
conditions. One percent formaldehyde solution in sea water buffered with borax
or neutralised with calcium carbonate perfectly preserved majority of meroplankton.
Equally good was one percent propylene phenoxetol buffered with borax.
Biochemical compostion of vaioous taxa showed variations according to their
age class, size groups metamorphosing stage, feeding mechanism, type of
organism fed and time of collection.
General distribution studies of 4 meroplankton taxa - Anthozoan larvae, cirripedia
larvae, sipunculoid larvae and gastropod larvae stowed abundance in the coastal
areas especially during the SW monsoon period. Based on the larval distribution
different zoo-geographical areas in the Indian Ocean are differentiated. |