Project synopsis: Reef zonation on Two-Mile reef, Sodwana Bay
(Compiled by A. MacDonald)
South-east African coral reefs are unique in their species composition and richness,
containing tropical, sub-tropical and endemic species. In order to manage these systems
and retain genetic diversity it has been recommended that highly diverse reefs in each reef
complex be zoned as no-take reserves. This is especially important for reefs subjected to
high levels of recreational diving, as reduction of diver-mediated influence on vertebrate
communities, which contribute to reef health, may be an important consideration in their
long-term protection.
The iSimangaliso Wetland Park Authority places no diving restrictions on any of the reefs in
the central reef complex (Fig. 1). The central reef complex comprises several large reefs, the
largest being Two-Mile Reef in the south of the complex. Two-Mile Reef is a very large reef
and is dived routinely along well-known dive paths by SCUBA enthusiasts. SCUBA divers
although very often well-intentioned have been observed to occasionally “touch” the reef.
This is usually due to lack of buoyancy control, which results in divers having to stabilise
themselves on reef structures. In “touching” the reef, fragile structures such as branching
coral colonies may be damaged and thus complexity in the reefs structure may be lost. This
loss of complexity can negatively impact coral reef communities. Damaged/disturbed parts
of the reef may have more patches of sand or bare rock than undamaged parts. Damaged
reefs also tend to become vulnerable to overgrowth by turf algae, which can further reduce
coral complexity.
Local dive operators maintain that the damage inflicted on the reefs along these dive paths
is negligible. Recently however, in an underwater visual census of fish diversity on the reefs,
the central reef complex was found to exhibit lower numbers than expected of certain reef
fish. Although these reef fish are often considered to be indicators of reef health, their low
number is not conclusive evidence that it is the divers that are affecting the reef. However,
further evidence may be obtained from direct observation of reef structures to determine if
the reefs are being damaged. A quick pilot survey of Two-Mile Reef, Sodwana Bay, was
therefore conducted in 2011 to test whether there were observable differences in reef
structure between frequently dived and un-dived parts of the reef.
Two photographic transects were taken, one along a frequently dived path on the reef
(Transect 1), and one along a section of reef that is not popular with SCUBA divers
(Transect 2). Each transect consists of twenty photographs and all pictures were captured
using a fixed-length focal arm, so all of the pictures have similar areas. Pictures were taken
every five metres along the underwater transects in order that the distance covered in each
transect was comparable in length. Each picture had ten randomly placed points, under
which the benthos is distributed. The benthos are the plants and animals found on the sea
floor. The photographs for each transect are available on Learn.
Corals grow in many different shapes or life forms and can be classified according to the
form they take. Examples of the different life form categories of corals and other benthic
organisms are given in Addendum A. You are expected to count and identify the benthos
observed under each point in your slides according to this addendum. Note that both biotic
and abiotic structures are of interest in this study. The abiotic structures are not categorised
in the addendum but you can assign these categories yourself. Once you have been
through all the slides; you might decide to group similar structures together into broader
categories that you think are relevant, according to the research that you have done.
You may then proceed to formulate hypotheses and to test them using appropriate statistical
methods.

Write a scientific report including abstract, introduction, hypothesis and aim