Seasonal Variation of Phytoplankton Pigments in the Laccadive Sea off Cochin
181
monsoon when the run-off from the backwaters was also maximum. During the rest of
the year there was comparatively little silicate in the water column.
4. Light Penetration
Secchi disk values fluctuate between about 3 m during June, July and August and
19.5 m (20-21 m station depth) in January (Fig. 4). There is a clear inverse relationship
o
....
N
cj
vi
.--_ _ _ 2
11 00 hrs
9 October
1968
T.CP = 172
3
11.40 hrs
24 July
1968
=112
5
6
11.50 hrs
12 August
1968
=136
7
09.15 hrs
26 Sept.
1968
= 90
11.00 hrs
1 April
1969
=114
Om
5
10
15
Total
20 Pigment
Imgm-3)
2 4 6 8 10
12.00hr s
25 April
1969
=83
I S.o = Secchi Di sc Depth 1m) : T.c.P. = Totol Column Pigment (mg m-2); 1--- -) Stat ion Bottom)
Fig. 7. Vertical distribution of phytoplankton pigments