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Ascidians constitute a large part of the intertidal and subtidal marine fauna and
with sponges and bryozoans make up the bulk of the sessile marine reef inhabitants.
Ascidian research includes taxonomic studies and description of new species. Sampling
to determine species distribution has been made in False Bay, Tstisikamma, St. Francis
Bay, Algoa Bay, East London and Mozambique.
The University of Port Elizabeth in collaboration with Rhodes University are involved
in natural product research. This involves the collection, identification and chemical
analysis of species collected. These extracts are tested to determine activity for
anti-cancer and anti-viral drug development research.
Previous collaboration has taken place with overseas institutions such as Coral
Reef Research Foundation in Palau, the National Cancer Institute in Washington DC,
and the Scripps Institution of Oceanography, University of California, San Diego.
This collaboration has lead to the discovery of not only new species but new chemical
compounds and has increased our knowledge and understanding of these organisms with
leaps and bounds.
Investigation into the effect of increased population density of the Cape reef-worm
Gunnarea capensis on the eastern Cape Rocky shores. The slow but persistent
increase in reef-worm population has been brought to our attention by members of
the public and surfing fraternity in Jeffrey’s Bay. The area is host to a large
number of holiday makers and the reef and its associated fauna is valued by the
inhabitants and users of the beach area. This project aims to address concerns on
the increase of the worm, biodiversity of other invertebrate species on the reefs
and the effect of human activity, e.g. harvesting of certain marine species.
A species list is being compiled for the East London area. This area has a number
of different rocky shore habitats and small didemnid species seem to dominate the
ascidian fauna in this area. As East London has generally a higher water temperature
than Port Elizabeth due to the shallow continental self and the influence of the
Agulhas current we may expect to find more typically tropical species in this area.
A species list is being compiled for the Port Elizabeth area. Although these animals
are common occupants of the intertidal areas little is know about them. Many of
the colonial species are brightly coloured and a number of Aplidium and
Didemnum species are commonly found. A number of species may be seen on spring
low tide when you look under overhangs or in protected crevices. The solitary ascidians
are frequently overlooked as many of the animals are totally overgrown by algae
or sponges. It is only when they are disturbed that the give away there hiding places
as their tunics contract, and before the siphons close the excess water is expelled
as a squirt of water, thereby the common name Sea-squirts. The best know solitary
ascidian species is the Redbait Pyura stolinifera. These animals are commonly
found on the rocky shore around southern Africa and have a cosmopolitan distribution.
The animals have a thick, strong, leathery tunic which protect the soft inner part
from predators. Individual can grow as large as a soccer ball and after severe storms
at the sea groups of these animals can be seen washed up on the beach. This happens
because the animals grow in large groups on offshore reefs and pinnacles were they
become too heavy and break off and the wash ashore. The soft orange-yellow inners
(branchial sac, intestine and gonads) of these animals is a favourite bait for anglers
and can be commercially bought at bait shops.
The University of Port Elizabeth currently houses a large collection of specimens.
Current research efforts are focussed on biomass and biodiversity estimates of the
reefs in the bay. This is done by quadrant sampling where species composition as
well as biomass of specific reefs is determined.
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