Article by Gavin W. Maneveldt
Department of Biodiversity & Conservation Biology,
University of the Western Cape
I
n the fifth and final part of this series on common
intertidal seaweeds of the Cape Peninsula, we look
at the encrusting coralline red seaweeds
(encrusting corallines). These seaweeds are widespread in shallow water in all of the world’s oceans,
where they often cover close to 100% of rocky substrates. Nowhere are they more important than in the
ecology of coral reefs. Not only do encrusting corallines
help cement the reef together, but they make up a considerable portion of the mass of the reef itself and are
important sources of primary production and food for
certain herbivores.
seaweeds, corallines possess the phycobilin photosynthetic pigments that give them their red coloration.
Unlike fleshy seaweeds though, corallines are calcified
(their cell walls are impregnated with lime) so that they
are extremely hard. When one considers that our teeth
are calcified, you can quite easily imagine how hard
these seaweeds are.
Local representatives of encrusting corallines are equally abundant throughout the intertidal zone of the Cape
Peninsula. Even so, they are a poorly known group of
seaweeds, readily recognizable as pink, pinkish-grey,
red, mauve or purple blotches as though a clumsy
painter’s apprentice spilled them all over the rock surfaces, animals and even other seaweeds. Like all red
Spongites yendoi is the most abundant encrusting cor-
A hierarchy of overgrowth interactions
between S. yendoi (1), P. ferox (2) and
S. impar (3).
The common encrusting corallines of the Cape Peninsula include Spongites yendoi, S. impar, Phymatolithon
acervatum, P. ferox, P. foveatum, Mesophyllum engelhartii and Heydrichia woelkerlingii.
alline in the intertidal, occurring from the mid intertidal
to the immediate subtidal zone. Its colour varies from
grey-pink in well-lit areas to mauve in shaded areas.
Individuals generally fuse together when crusts meet,
so that large expanses of the coralline are often
thought of as a single seaweed. This coralline is closely
The grey-pink S. yendoi is often closely
associated with the territorial ‘gardening’
limpet, S. cochlear.