Biology of fouling in Karwar waters is presented. The composition of fouling communities, their fluctuations in relation to hydrographical factors such as temperature, dissolved oxygen, salinity and the influence of the nature and texture of the substratum on fouling communities are discussed

Kusuma, M.S.

Nageshwara Rao, P.N.

Neelakantan, B.

Aquatic Commons

Fish. Techno!. (1982) 19, 113-118 113 
reliminary ccount on the Intensity o·f 
1 n arwar aters 
P. NAGESHWARA RAO, M. S. KUSUMA and B. NEELAKANTAN 
Department of J11arine Biology, Karnataka Uuiversity, Kodibag, Kanvar-581 303 
Biology of fouling in Karwar waters is presented. The composition of fouling 
communities, their fluctuations in relation to hydrographical factors such as tempe-
rature, dissolved oxygen, salinity and the influence of the nature and texture of the 
substratum on fouling communities are discussed. 
In recent years, considerable attention is 
being paid towards the study of fouling or-
ganisms which attach on to all kinds of stru-
ctures in saline waters causing serious pro-
blems to the submerged timber structures, 
piles, pillars, buoys and the hulls of water-
crafts. While information is available on the 
fouling organisms of the other Indian regions, 
(Palekar & Bal,1957; Ganapathy eta!., 1958; 
Antony Raja, 1959; Nair, 1965, 1967; Nair, 
1967 b; Menon & Nair, 1971; Menon et. a!., 
1970). Virtually nothing is known on this 
important group from the Karwar waters. 
It is in this context, an attempt has been 
made to study the composition of the foul-
ing organisms of Karwar, their distribution 
and differential seasonal abundance. 
Karwar bay (14° 48 1-51'N and 74° 061E) 
(Fig. 1) is an outpush of Arabian sea with 
Kali river emptying into it on the northern 
side. During the south- west monsoon 
period which begins in early June, the bay 
waters get diluted with rain water and estu-
arine discharge, decreasing the salinity and 
temperature but increasing the turbidity. 
Based on the influence of the monsoon, the 
year can be distinguished into three well-
-defined periods, the pre-monsoon (Feb-
May), monsoon (June-Sept.) and the post-
monsoon period (Oct.-J an). 
The two stations selected (Kodibag and 
Baithkol) were 5 km from each other and 
represent two different ecological habitats. 
Kodibag is situated at the Kali river mouth 
and Baithkol, is located to the south 
of the bay taking an incurve from the inshore 
waters (Fig. 1). Owing to the intense opera-
tion of fishing vessels, this locality is subjected 
Vol. 19, 1982 
to pollution with lube oil and organic matter. 
The depth vary from 5-8 m and 6-8 m for 
stations 1 and 2 respectively in between the 
tidal shifts. 
( 
KALI~IADI 
'r~~'0 
1 ''"'"" TOWN ~I 
KURMACoAD 
SUNGHERI 
KARWAR Bi\Y I 
~.8 N~ '~AITHKOL 
A . 
Q ' 
74°- 6' 7' 8' 9' 
Fig. 1. Karwar bay showing test sites Kodibag (A) 
and Baithkol (B) 
Material and Methods 
Racks (60 x 30 em) with fixed glass panels 
(15 x 10 em) were suspended in the water 
at a depth of 4 mat both the stations. Fort-
nightly data were collected for seven months 
from March to September 1979, from smooth 
and rough glass panels immersed vertically. 
The observations and analyses of the physico-
chemical parameters were performed by 
standard methods (Salinity-Mohr Knudsen 
method, Oxygen-Winkler method, Tem-
perature-Thermometry and vertical extinc-
tion co-efficient by S. D. reading/0.95). 
Table 1. Settlement of fouling organisms in Kodibag (Station 1) 
Balanus Oysters Polychaetes Bryozoans 
A B A B A B A B 
a b a b a b a b a b a b a b a b 
March 1. 61 51.69 61 51.69 2 1.69 2 1.69 45 38.14 45 38.14 10 8.47 10 8.47 
2. 63 62.94 65 51.57 1 0.99 4 3.18 30 29.97 46 36.51 9 8.99 11 8.71 
April 1. 63 46.67 63 46.67 3 2.22 3 2.22 62 45.82 62 45.82 7 5.19 7 5.19 
2. 58 44.62 67 45.27 3 2.31 6 4.05 61 46.92 65 43.91 8 6.16 10 6.76 
May 1. 45 48.91 45 48.91 1 0.00 0 0.00 40 43.48 40 43.48 7 7.61 7 7.61 
2. 41 44.57 46 46.47 1 1.09 3 3.03 41 44.57 41 41.42 9 9.78 9 9.97 
June 1. 40 72.56 40 72.56 0 0.00 0 0.00 9 16.36 9 16.36 6 10.91 6 10.9 
2. 38 76.00 48 74.99 2 4.00 0 0.00 7 14.00 7 10.93 3 6.00 9 14.06 
July 1. 41 93.17 41 93.17 0 0.00 0 0.00 3 6.83 3 6.83 0 0.00 0 0.00 
2. 36 100.00 28 87.50 0 0.00 0 0.00 0 0.00 4 12.50 0 0.00 0 0.00 
August 1. 1280 99.77 1280 99.97 1 0.11 1 0.11 2 0.22 2 0.22 0.00 0 0.00 
2. 1664 99.84 1320 99.63 0 0.00 1 0.05 1 0.08 2 0.16 1 0.08 2 0.16 
September 1. 1250 99.97 1250 99.97 1 0.11 1 0.11 0 0.00 0 0.00 2 0.22 2 0.22 
~ 2. 1300 99.93 1340 99.63 0 0.00 1 0.07 0 0.00 0 0.00 1 0.07 4 0.30 [10 
::c 
1:!:1 A = Short term panel; B = Long term panel; a = Frequency of occurrence; b = Relative frequency of occurrence ( %) ; :.:0 
>-<: I = Ist fortnight; 2 = lind fortnight 
..., 
1:!:1 (j 
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FOULING IN KARWAR WATERS 
viridis on the panels. However, it is gener-
aiiy known that the dissolved gases and 
nutrients have a great effect on fouling 
organisms. Only a marginal fluctuation 
in oxygen content was observed at station 2 
exhibiting the relative stability of the water 
column. 
Turbidity increas'es due to silt, detritus 
and particulate matter in the medium, 
reducing the penetration of light and pre-
venting the attachment of fouling organisms 
to a greater extent (Nair, 1965). Corres-
ponding values of the extinction co-efficient 
are enumerated in Table 3. Turbidity 
increased considerably in the monsoon 
season and more so in the estuarine region 
because of heavy influx. The s·ettlement 
of fouling organisms depended on the pri-
mary profile of micro-foulers, whose growth 
intensity in turn affected by high turbidity, 
prevented the colonisation of successive 
foulers on the panels. 
Based on the tests conducted and results 
obtained, it was seen that the colour and 
texture of the substratum had great effect 
on the attachment of fouling community. 
Although rough glass panels provided a 
better substratum for the attachment of 
foulers, their grey colour affected the att1-
chment but a relatively greater number of 
fouling organisms was noticed over the 
smooth and transparent glass panels. 
In the fortnightly and monthly records 
of fouler settlement (Table 1 and 2) at least 
two variants of the Balanus amphitrite 
could be recognised. The oyster community 
on the panels, comprised of two species 
namely Crossostrea madrasensis and C. 
gryphoides. Sebellaria spinulosa and Poma-
toceros tdquetor were amongst the common 
polychaetes that were found interspersed on 
the panels, while bryozoans were represen-
ted by five dominant species namely Bugula 
cucu!lata, Alderina arabianensis, Schizoporella 
cochinensis, No/ella papuensis and Bower-
bankia imbricata, the hydroids were composed 
of as yet unidentified species. 
Except for a decline in the population 
during the monsoon season, the barnacles 
were found to occur throughout the period 
of study. Their attachment slowed on 
Vol. 19, 1982 
117 
immediately after the monsoon and showed 
peak settlement during January-April. 
During the monsoon season there was no 
attachment of oysters whereas in the pre-
monsoon there was fairly good attachment 
at both the stations. The fouling intensity 
was more conspicuous on long term panels 
than on short term ones. 
The settlement of bryozoans was heavy 
in the estuarine region during the pre-mon-
soon and was absent during the monsoon 
while at station 2 they were sparse. 
The two species of polychaetes encountered 
in the Karwar waters were totally absent 
during the monsoon period with peak set-
tlement in station 1 during the pre-monsoon 
while at station 2 they appeared only after 
monsoon. 
The colonial hydroids were the predo-
minant pioneer fouling animals which formed 
a base for the settlement of other fouling 
communities over the panels. The genera] 
trend of the two species encountered was 
increase during the pre-monsoon and decrease 
in the monsoon respectively. 
The present study has taken into consi-
deration, the intensity of fouling organisms 
during March-September. The stations 
studied were unique in the sense that there 
was heavy fluctuation in salinity and tem-
perature (station I) and moderate pollu-
tion caused by oil and dredging (station 2). 
The intensity of fouling ranged in relation 
to the hydrographical conditions. The 
number of fouling species occurring in the 
Karwar waters is very much less compared 
to other places along the Indian coast 
especially, Madras and Vishakapatnam. 
This may be due to more stable hydrographic 
conditions prevailing in the latter places. This 
may also be due to the lesser rain fall along 
the east-coast inshore than over the areas 
of the present study where the coastal waters 
are very much diluted on account of the 
ingress of freshwater. Similar results have 
also been obtained in the case of Cochin 
harbour (Cheriyan, 1966). Of the various 
species of fouling organisms Balanus sp. 
constituted the most important component 
of the fouling community of Karwar as was 
found for other regions. 
118 P. NAGESWARA RAO, M. S. KUSUMA AND B. NEELAKANTAN 
The settlement period of barnacles at the 
different harbours revealed the following 
trends. While peak settlement occurred 
during April and May in Vishakapatnam, 
it was in May, and October to December 
at Cochin harbour (Nair, 1965). In Man-
galore waters, the foulers were found to be 
abundant during the pre and post-monsoons 
(Menon & Nair, 1971) and as far as the 
experiments reveal, heavy settlement occurred 
during August-September in Karwar waters. 
However, the settlement of barnacles 
occurred throughout the period of study in 
the Karwar region. Occurrence of oysters 
was during April and May in Madras coast 
(Paul, 1942) and during August and Septem-
ber in Karwar while in Mangalore waters 
they settled throughout the year. The settle-
ment of bryozoans along Karwar was during 
March, April and May whereas it was in 
July, August in Cochin. However, the 
settlement of polychaetes resembled that of 
barnacles and was found to decrease during 
the monsoon. 
We are greatly indebted to the University Grants 
Commission for financial assistance. 
References 
Antony Raja, B. T. (1959) J. Mar. bioi. 
Ass. India. 1, 180 
Cheriyan, P. V. (1966) J. Timb. Dev. Ass. 
India. 12, 20 
Ganapathy, P. N., Lakshmana Rao, M. V & 
Nagabushanam, R. (1958) Andhra Univ. 
Mem. Oceanogr. 62, 193 
Menon, N. R. & Nair, N. B. (1971) Mar. 
Bioi. 8, 280 
Menon, N. R., Katti, R. J. & Shetty, H.P.C. 
(1970) Mar. Biol. 41, 127 
Nair, N. B. (1967) Proc. Symp. Crustacea. 
Mar. Bioi. Ass. India. 4, 1254 
Nair, U. K. (1965) Jour. Sci. Ind. Res. 
24, 483 
Nair, U.K. (1967 b) Hydrobiologia. 30, 503 
Palekar, V. C. & Bal. D. V. (1957) J. Bom-
bay nat. Hist. Soc., 54, 962 
Paul, M. D. (1942) Proc. Indian Acad. 
Sci. 15 (B), 1 
FISHERY TECHNOLOGY 


Preliminary account on the intensity of fouling in Karwar waters

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Preliminary account on the intensity of fouling in Karwar waters

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