1. Konstantin Tkachenko Ph.D.
Department of Natural and Geographic Sciences
Samara State Educational University
Samara, Russia

2. Location of study sites in Ihavandippolu atoll
Coordinates
Latitudinal extension:
7° 06’ – 6° 54’ N
Longitudinal extension:
72°47’ – 72°59’ E
Size
Area: 330 km2
Maximal dimension from W to E
is similar to that from N to S
and equal to 21 km
N

3. Material and methods
Sampling
Depth: 3-7 m
Phototransect method
4×40 m photransects
20 photoquadrats per transect
Each photoquadrat = 0.4 sq. m
Estimation
CPCe software
50 points per photoquadrat
Percent cover of:
1. Hard coral
2. Dead hard coral
3. Soft coral
4. Coralline algae
5. Macroalgae
6. Rock, rubble, sand

4. Census of herbivorous fish
Three major families of
herbivorous fish were counted:
Acanthuridae
Scaridae
Siganidae
4×10 min timed swim visual
estimations
Acanthuridae Scaridae
Siganidae

5. Distribution of major benthic and substrate categories on
study sites
Macroalgae cover < 0.5 %
in all sites

6. Distribution of 12 dominant genera on study sites

7. Site 1
2
0.6
12.8
Distribution of specific
coral groups with
different susceptibility
to bleaching (% cover)
Susceptible Tolerant Resistant
Typical reef on site 1

8. Site 2
Distribution of specific
coral groups with
different susceptibility
to bleaching (% cover)
Susceptible Tolerant Resistant
1 1.9
19.5
Typical reef on site 2

9. Site 3
5.7
0.2
22.3
Distribution of specific
coral groups with
different susceptibility
to bleaching (% cover)
Susceptible Tolerant Resistant
Typical reef on site 3

10. Site 4
18.5
1.2
20.5
Distribution of specific
coral groups with
different susceptibility
to bleaching (% cover)
Susceptible Tolerant Resistant
Typical reef on site 4

11. Site 5
11
2.1
8.9
Distribution of specific
coral groups with
different susceptibility
to bleaching (% cover)
Susceptible Tolerant Resistant
Typical reef on site 5

12. Site 6
14.6
2.1
16.5
Distribution of specific
coral groups with
different susceptibility
to bleaching (% cover)
Susceptible Tolerant Resistant
Typical reef on site 6

13. Site 7
28.3
0.8
10.3
Distribution of specific
coral groups with
different susceptibility
to bleaching (% cover)
Susceptible Tolerant Resistant
Typical reef on site 7

14. Site 8
15.3
4.7
6.8
Distribution of specific
coral groups with
different susceptibility
to bleaching (% cover)
Susceptible Tolerant Resistant
Typical reef on site 8

15. Site 9
38.1
0.1
13
Distribution of specific
coral groups with
different susceptibility
to bleaching (% cover)
Susceptible Tolerant Resistant
Typical reef on site 9

16. Site 10
18.5
0.1
2.8
Distribution of specific
coral groups with
different susceptibility
to bleaching (% cover)
Susceptible Tolerant Resistant
Typical reef on site 10

17. Site 11

18. Herbivorous fish
Abundant herbivore fish
especially acanthurids prevent
local coral reefs from phase shift
to algae-dominated communities

19. Effect of SW and NE monsoons and
related hydrodynamic patterns on Ihavandippolu atoll
N

20. Status of coral communities in Ihavandippolu atoll
Stable coral community with
high coral cover and
dominance of susceptible
genera
Plot is based on quantitative estimation of study sites
and visual inspection of several reefs
Balanced coral community
in terms of proportional
abundance of susceptible and
resistant + tolerant genera
Climax coral community with
dominance of resistant genera
and low total coral cover
Unstable coral community
with low total coral cover
and dominance of
susceptible genera
Collapsed coral community
with single occurrence of
live corals

21. Conclusions
1. Inner reefs protected from the ocean swell and opened to the influence of internal
waves generated by SW monsoon revealed the most healthy coral communities with
relatively highest coral cover and proportion of susceptible genera
2. Reefs located in the center of atoll’s lagoon exhibited climax coral communities with
low coral cover and diversity and dominance of resistant genera. Susceptible genera
remain degraded after the first mass coral bleaching event in 1998.
3. Northern and eastern outer reefs most subjected to the influence of NE monsoon
demonstrated unstable coral communities with low coral cover and high proportion
of dead corals or totally degraded reef ecosystems
4. High abundance of herbivorous fish prevent microalgae blooms on local coral reefs
5. Increase of frequency of thermal anomalies may cause further decline of coral cover
in Ihavandippolu atoll and strategic shift at most reefs to the dominance of coral genera
that are more resistant to changing environment

22. Thank you for attention