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Significant results of reef surveys and long-term monitoring on South African marginal reefs

Significant results of reef surveys and long-term monitoring on South African marginal reefs Michael Schleyer, Louis Celliers & Alke Kruger Oceanographic Research Institute, P.O. Box 10712, Marine Parade, Durban 4056, South Africa schleyer@ori.org.za. LOCAL SPHERE OF OPERATIONS

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Significant results of reef surveys and long-term monitoring on South African marginal reefs

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  1. Significant results of reef surveys and long-term monitoring on South African marginal reefs Michael Schleyer, Louis Celliers & Alke Kruger Oceanographic Research Institute, P.O. Box 10712, Marine Parade, Durban 4056, South Africa schleyer@ori.org.za

  2. LOCAL SPHERE OF OPERATIONS Only ~40 km2 coral reef over 120 km In three reef complexes + some scattered reef Marginal, high-latitude, non-accretive; 8-27 m All in MPAs & WHS

  3. Taxonomy Biodiversity Coral reproduction Reef damage & sustainable capacity Recruitment COTS Natural products Oceanography Coral genetics Coral bleaching Reef surveys Reef monitoring ACTIVITIES

  4. BIODIVERSITY Most abundant genera: Sinularia, Lobophytum, Favia, Favites, Montipora and Echinopora High level of endemism

  5. REEF SURVEYS(Essential due to increasing use) • Digital imaging • 7 years to complete • 4.2 GB of data

  6. Coral Community Structure • 20 communities at 55% similarity • e.g. Cluster: • 11 Acropora-rich Kosi

  7. Zonation for Use (Based on coral sensitivity to damage, reef carrying capacity and depth) N : Shallow, snorkellers L : Learner divers U : General use RA : Advanced divers RE : Experienced divers RS : Special biota S : Sancuaries Kosi

  8. N S Kosi Rabbit Rock Sodwana complex Red Sands, Leadsman

  9. MONITORING (1993 – present) CLIMATE CHANGE

  10. Nine-mile Reef

  11. Temperature Data Bleaching 0.27°C p.a.

  12. CORAL BLEACHING • In 2000 • Affected <12% cover • Mainly Montipora, Alveopora & Acropora • 9.5 weeks @ ≥27.5ºC • 4 days @ ≥28.8ºC Celliers & Schleyer, 2002

  13. Reef top Quadrats standardised by calibration & correction (mean error = 2.0%, range 1.2 - 2.8%) Reef-sediment interface

  14. 1993 1996 1998 Transect C (reef-sediment) 2001

  15. Transect E (reef top) 1993 1996 2001 1998

  16. % Cover for all transects

  17. Total number of recruits and mortality Bleaching Recruitment success

  18. CONCLUSIONS: • · South African reefs are limited, marginal and manifest a gradient in community structure • Climate change  sea warming  soft to hard corals  bleaching threshold • This appears to be “silently” affecting coral recruitment success • · Future aragonite saturation state,  reef formation, hard corals • · Studies on SA reefs may elucidate the relationship between these complex mechanisms and provide an insight to the global future of corals

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