412
N. BAIAKFtISHNAN NAIR AND M. SARASWATHY
TABLE VI. THE SEASONAL SETTL.EMENT OF SHIPWORMS ON SHORT-TERM
PANELS (“A” SERIES) AT C o a m HARBOUR
Period of immersion
Pre-monsoon
1st Feb.-1st Mar
1st March-1st April
1st April-1st May
,
1st May-1st June
Monsoon
1st June-1st July
1st July-1st Aug.
1st Aug.-lst Sept.
1st Sept.-1st Oct.
Po8t-mo?tsoon
1st OCt.-lst NOV.
1st Nov.-1st Dec.
1st Jan.-1st Feb.
1st Dec.-lst Jan.
Total for the year
Nausitora hedleyi
Panel
No. Inter- Sub- Bottom
tidal tidal
Teredo fwcifera
Inter- Sub- B
o
~
tidal tidal
A1
- -
3
A 2 - - -
A 3 - - -
A 4 - - -
A1
- - -
A2
- .7
A3
9
3
21
A4
-
6
9
A1
2
15
9
A2
- 43
31
A3
- 11 9
A4
-
3
1
11
81
90
11 159 607
35 217 305
30 145 340
81 113 268
- -
-
2
-
7
14
26
13
12
49
179 667 1632
More recently Saraswathy and Nair (1969) investigated the settlement of N . hedleyi at Cochin harbour (Tables VI and VII).
In Table VI is presented the results obtained at Cochin harbour
from an examination of the short-term blocks representing larval
settlement during 30 days intervals of the pre-monsoon, the monsoon
and the post-monsoon. To the question whether the settlement takes
place in a restricted season or evenly throughout the year, this system
provides a direct answer. Settlement of Nausitora hedleyi at Cochin
harbour is seen as strictly seasonal. Since its inception in July, the
settlement continued uninterruptedly till about February. The data
also show that during this study, November represents a period of
intense settlement with a period of fair settlement during August.
Table VII presents results from long-term blocks and indicates the
progress of settlement .during the pre-monsoon, the monsoon and the
post-monsoon periods. The general trend of settlement is the same in
both series with little settlement during the pre-monsoon period. This
set also shows how the monthly settlement may be modified when test