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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
[email protected]
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
ACTIVITIES
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Taxonomy
Biodiversity
Coral reproduction
Reef damage &
sustainable capacity
• Recruitment
• COTS
•
•
•
•
Natural products
Oceanography
Coral genetics
Coral bleaching
• Reef surveys
• Reef monitoring
BIODIVERSITY
Taxon
Milleporina
Scleractinia
Alcyonacea
Ascidiacea
Porifera
Genera
1
43
11
17
20
Species
1
93
39
30
?
Most abundant genera: Sinularia, Lobophytum,
Favia, Favites, Montipora and Echinopora
High level of endemism
REEF SURVEYS
(Essential due to increasing use)
• Digital imaging
• 7 years to complete
• 4.2 GB of data
Coral Community
Structure
20 communities at
55% similarity
e.g. Cluster:
• 11 Acropora-rich
Kosi
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
N
Kosi
Rabbit Rock
S
Sodwana complex
Red Sands, Leadsman
MONITORING
(1993 – present)
CLIMATE CHANGE
Temperature 
CO2 Increase
Could increase
reef formation
Aragonite saturation
Will decrease
state 
reef formation
Nine-mile Reef
time (month and year)
Apr-04
Oct-03
Apr-03
Oct-02
Apr-02
Oct-01
Apr-01
Oct-00
Apr-00
Oct-99
Apr-99
C
0.27°C p.a.
Oct-98
Apr-98
Oct-97
Apr-97
Oct-96
Apr-96
o
31
29
27
25
23
21
19
17
15
Oct-95
Apr-95
Oct-94
Apr-94
sea temperature
Temperature Data
Bleaching
CORAL
BLEACHING
• In 2000
• Affected <12% cover
• Mainly Montipora,
Alveopora & Acropora
• 9.5 weeks @ ≥27.5ºC
• 4 days @ ≥28.8ºC
Celliers & Schleyer, 2002
Reef top
Quadrats standardised by calibration & correction
(mean error = 2.0%, range 1.2 - 2.8%)
Reef-sediment interface
1993
Turbinaria
area (mm2)
8.00E+04
1996
6.00E+04
4.00E+04
2.00E+04
0.00E+00
1993
1995
1997
1999
2001
year
1998
Transect C
(reef-sediment)
2001
Transect E
1993
1996
(reef top)
Sinularia
area (mm2)
80000
60000
40000
20000
0
1993 1994 1995 1996 1997 1998 1999 2000 2001
year
2001
1998
% cover
% Cover for all transects
50
45
40
35
30
25
20
15
10
5
0
Alcyonacea
Scleractinia
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
Total number of recruits and mortality
50
45
40
35
30
N 25
20
15
10
5
0
Bleaching
Mortality
Recruitment
success
Recruits
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
CONCLUSIONS:

South African reefs are limited, marginal and
manifest a gradient in community structure

Climate change  sea warming  soft to hard
corals  bleaching threshold
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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