Article by Gavin W. Maneveldt
Department of Biodiversity & Conservation Biology,
University of the Western Cape
I
n this, the second in the series
on common intertidal seaweeds of the Cape Peninsula,
we look at the brown seaweeds common to our rocky
shores, with the exception of kelp,
which will be covered in the next
issue. Unlike the green seaweeds
mentioned in a previous issue,
these brown seaweeds are generally
slower growing and are less tolerant of salinity and temperature extremes and thus more prone to desiccation stress. They therefore tend
to occur lower down on the shore
than the green seaweeds.
The usually yellowish-brown colour
with grey or blackish tinges of the
brown seaweeds comes from the
presence of chlorophyll a and c, as
well as an additional xanthophyll
pigment called fucoxanthin. Some,
however, are totally black and are
often mistaken for red seaweeds,
but a good way to distinguish between brown and red seaweeds in
the field is to perform a simple test.
Take the seaweeds and rub them
onto the back of your hand. If your
The stringy seaweed, Chordariopsis capensis, is found high up on the
shore in the shelter of rock pools.