Centro de Desenvolvimento Sustentável das Zonas Costeiras


Schleyer et al. (1999). A Preliminary Assessment of Coral Bleaching in Mozambique
The 1997-1998 El Nino southern oscillation (ENSO) caused elevated sea temperatures that resulted in global coral bleaching. Coral reefs constitute an important biological resource in terms of their complex biodiversity and are the basis for tropical reef fisheries and marine ecotourism. They represent one of Mozambique's main coastal assets and its coastal communities and growing tourism industry rely mainly on reef-based resources. Mozambican artisanal fisheries are largely centred on reefs and are responsible for about 70% of the total catch, highlighting their importance. Most tourism similarly occurs along the coast where the best infrastructure is established, especially near the coral reefs of Pemba, Mozambique Island, the Bazaruto Archipelago, Inhaca Island and Ponta do Ouro.

Reefs along the Mozambican coast consist of fossilized dune and beach rock, colonized by corals to a varying degree. The shoreline has been successively exposed and submerged during the millennia and the reefs fall in three regions:

  1. the northernmost section, which extends over 770 km from the Rovuma River in the north to Pebane in the south (17º20'S), mainly coraline;
  2. the central section, between Pebane (17º20'S) and Bazaruto Island (21º10'S), a distance of about 950 km, which is classified as a swamp coast, and
  3. the southern section, which stretches for 850 km from Bazaruto Island southwards to Ponta do Ouro (26º50'S), comprising mainly patchy reefs.

As the extent of reef loss during the 1997 - 1998 El Nino phenomenon was unknown in Mozambique, the current survey was undertaken to:

  1. Assess the consequences of coral bleaching in Mozambican waters.
  2. Train Mozambican scientists in this specialized field to increase the scientific capacity of the country.

The survey of coral bleaching was undertaken from March 24 to April 8, 1999 at the end of summer. Evidence of bleaching was sought for the present and past year in six localities, these being tabulated below in order from north to south. Dives were executed on a total of 17 reefs and a visual assessment was made of reef type, faunistic cover and the extent of reef damage attributable to bleaching and crown-of-thorns starfish (COTS). Quantitative measurements using transect techniques proved inappropriate due to the sea conditions, the nature and condition of the reefs, and the fact that most of the work was done using snorkel rather than SCUBA. However, it proved possible to record random video-photo quadrats at ten of these stations for later analysis. The reefs surveyed were:

The effects of El Nino bleaching in Mozambique were most extensive on exposed reefs in the north (up to 99%) and this diminished further south except at Inhaca Island where serious recent bleaching (90%) was encountered. Extensive COTS damage was also found at Bazaruto (80%) and Inhambane (95-98%). The COTS outbreaks commenced in 1995-1996 and, as sufficient time has elapsed for reef erosion and collapse to occur, the damage on these reefs was more pronounced. The consequences of the El Nino bleaching are going to be even more serious as coral mortality on the northern reefs was as high as 99%; a similar progression in the collapse of reef structure on the seriously bleached reefs is anticipated. The biodiversity of these sites will be impaired as only low coral recruitment was observed at the Bazaruto COTS site. The fish populations on the damaged reefs, the basis of many of Mozambique's valuable artisanal fisheries, were also poor. Both the fisheries and the tourism value of these sites will thus be affected, parameters that will have to be quantified.

Further work and monitoring at three localities in the north of Mozambique and three in the south was thus proposed. Bleaching, COTS and control sites will be included to:

  1. Establish whether further bleaching occurs.
  2. Monitor and compare reef recovery at bleaching and COTS sites.
  3. Consider appropriate procedures for intervention if reef recovery proves unlikely or slow, e.g. the artificial propagation and transplantation of corals.
  4. Develop a management plan for Mozambique's coral reefs.</p>

Further development of Mozambican staff was planned during the survey to deal with the situation. MICOA and CORDIO will fund a course later in 1999 to train MICOA, UEM and IIP staff and students in the identification of reef fauna, appropriate methods for the work and the principles of reef management. Monitoring will commence immediately after the course. Two students will register for M.Sc. degrees through ORI and execute the programme under the joint supervision of MICOA and ORI. Similar studies are currently being undertaken at ORI, including groundwork on coral culture, and collaboration between these organizations will provide added impetus to the Mozambique-South African coral research programme