Antifouling activity is one poorly investigated property of
seaweed natural products. To determine, in the field,
whether seaweeds contain chemicals able to influence the
settlement of fouling organisms, crude organic extracts
from
Stypopodium zonale
,
Dictyota menstrualis
(Phaeophy-
ceae) and
Laurencia obtusa
(Rhodophyceae) were incorpor-
ated at natural volumetric concentrations, into hard stable
gels that served as substrata for fouling in the experiments.
Fouling organisms settled at a significantly higher rate on
plates treated with
S. zonale
extracts than on control gels,
while settlement was strongly inhibited on gels containing
L. obtusa
extracts. Fouling on gels treated with the
D.
menstrualis
extract was not significantly different from the
fouling found on control gels. The findings suggest that the
broad antifouling properties of the crude extract of
L.
obtusa
inhibit the settlement of fouling as well as hinder the
development of settled fouling species, thereby reducing
the richness of species. The results imply that
L. obtusa
possibly harbours powerful agents that can be explored for
the development of antifouling technology