Studies on Limacina inflata d'Orbigny (Thecosomata, Gastropoda) in the Indian Ocean 393
grazing, following the bloom of phytoplankton. As Limacina inflata is predominantly
a herbivore, this follows closely the general trend of increase or decrease of zooplankton.
This year-to-year change in the cyclic changes of the ecosystem might probably have been
introduced by the earlier or later setting in of the NE monsoon.
IV. Latitudinal, Seasonal and Diurnal Variations of Limacina
inflata along 110 0 E
In 1962- 63 the Division of Fisheries and Oceanography, CSIRO Cronulla, with the
collaboration of the oceanographic laboratory, ORSTOM New Caledonia, undertook
6 seasonal biological cruises, at 2-month intervals along 110° E meridian between 32 °
and 9° S. The aim of these cruises and other details have been published by ROCHFORD
(1969 and TRANTER (1973) this volume).
Duplicate collections from these cruises were sent to IOBC and utilized for comparison.
The data collected for the identification of thecosomes are being worked out; only
the species Limacina inflata is presented here. The number of Limacina inflata from each
collection was converted to log 10 and a contour was drawn at different grades of
density; figures were prepared for day and night (Fig. 9 a, b).
1962
VIII IX X XI XII
11
0
14
17
(@
20
23
26
29 .
@
Vi
~32
(1.1
'tJ
.2
S
23
26
29
VII VIII
0
~ Go
t9
Fig. 9. Latitudinal, diurnal and seasonal variations of Limacina inflata along 110° E Contours:
log of individuals per 200 m 3 a Day b Night