2. INTRODUCTION
Coral bleaching is the phenomenon wherein the
corals lose their vibrant colour and turn white due
to environmental stressors.
Bleached Corals continue to live , but
they are more vulnerable to disease and
starvation.
3. TIME LAPSE OF CORAL BLEACHING
Source: Blue Planet Oceans from BBC America
INTRODUCTION
4. HOW DOES A BLEACHED
CORAL LOOK LIKE?
Most bleached corals
appear bright white
but some are blue,
yellow or pink due to
the pigment protein
present in the corals.
BLEACHED CORALS IN THE PACIFIC
Image taken from https://www.google.com/imghp?hl=en&authuser=0&ogbl
5. HOW DOES A BLEACHED
CORAL LOOK LIKE?
HEALTHY
CORAL
HEALTHY
CORAL
STRESSED
CORAL
STRESSED
CORAL
BLEACHED
CORAL
BLEACHED
CORAL
DEAD
CORAL
DEAD
CORAL
CHANGING CORAL COLORS
Photo Credit-
Dive Wananavu Fiji
Photo Credit-
Richard Vevers
Photo Credit-
Tim McClanahan
Photo Credit-
Richard Vevers
Image taken from https://www.google.com/imghp?hl=en&authuser=0&ogbl
6. PROCESS
Bleaching occurs when
coral polyps expel
zooxanthellae that live
inside their tissue,
causing corals to turn
white.
ENDOSYMBIOSIS IN CORALS
Source- https://serc.carleton.edu/index.html
7. provides vibrant colour
provides energy after
photosynthesis
Zooxanthellae
Coral Polyp
provides shelter
provides carbon dioxide for
photosynthesis
ENDOSYMBIOSIS IN CORALS
Images taken from https://www.google.com/imghp?hl=en&authuser=0&ogbl
ENDOSYMBIOTIC RELATIONSHIP
Photo Credit-
Todd C. LaJeunesse
Photo Credit-
Charles LoBue/EPA
8. Tentacle of coral
polyp containing
zooxanthallae
Zooxanthellae
produces Reactive
Oxygen Species
Coral Polyps expel out
the zooxanthellae
PROCESS
Under stressful environmental conditions,
the zooxanthallae begins to produce reactive oxygen species, which are toxic for
the coral polyps and resultantly corals expel the algae for short-term survival.
9. PROCESS
Since, the zooxanthellae produce majority of coral coloration, the coral tissue
becomes transparent, revealing the coral skeleton made of calcium carbonate.
Endosymbiotic
Relationship breaks
Coral loses its color Coral Dies if it can restore
normal conditions
10. CAUSES OF CORAL BLEACHING
Rise in Ocean Temperature
Ocean Acidification
Solar Radiation and Ultraviolet Radiation
Infectious Diseases
Chemical Pollution
Increased Sedimentation
Human Induced Threats
12. MAJOR BLEACHING EVENTS
57/100 of the
Worlds Total
Coral Location
were severely
affected, while
16 locations
were
moderately
affected.
1998 2005
A total of 40
coral locations
were affected
in the summers
of 2005-2006
2010
53 coral
locations were
affected in 2010
mass bleaching
event.
2016
Total 54
locations were
affected in the
time period of
2014-2017, with
peak
destruction in
2016.
In the last 30 years, we have lost over 50% of the world’s Corals.
13. RECENT BLEACHING EVENTS
2020 During the 2020 event, 25% of reefs surveyed had severe levels of coral bleaching.
2021 In 2021-22, sea surface temperatures in Western Australia remained in the highest 10% of observations since 1900.
In 2022, aerial surveys confirmed the fourth mass bleaching event to impact the Great Barrier Reef in seven years.
2022
Heat caused stress on coral reefs across the Gulf of Mexico, northern Atlantic Ocean, and the Caribbean Sea, as well
as the eastern Pacific Ocean. The extreme heat stress triggered a large-scale coral bleaching event impacting nearly a
dozen countries.
Nearing mid-October, waters around the Florida Keys were under a bleaching watch. Further south, waters around
parts of Cuba and the Bahamas remained at bleaching alert level 2, the highest level of the scale, signifying that
severe bleaching and mortality are likely.
JULY
2023
OCT
2023
14. WHY DOES CORAL BLEACHING MATTER?
When corals die, reefs rarely come back.
With few corals surviving, they struggle to reproduce, and entire
reef ecosystems deteriorate.
Bleaching also matters because it’s not an isolated phenomenon.
According to the National Oceanic and Atmospheric Association,
between 2014 and 2017 around 75% of the world’s tropical coral
reefs experienced heat-stress severe enough to trigger bleaching.
For 30% of the world’s reefs, that heat-stress was enough to kill
coral.
15. IMPACTS OF CORAL BLEACHING
Affects the Food Chain
Loss of Biodiversity
A decline in Economy
Affects Food Availability
Impacts Coastal Protection
BEFORE AND AFTER A BLEACHING EVENT
Source: National Geographic
16. THE GREAT BARRIER REEF IS SUFFERING
The 2015–2016 event resulted in the bleaching of more than
half of all the coral in the Great Barrier Reef.
Coral bleaching affected 91% of reefs surveyed along the
Great Barrier Reef IN 2022, according to a report by
government scientists that confirms the natural landmark
has suffered its sixth mass bleaching event on record.
IMAGE TAKEN FROM CANVA
17. IMPORTANCE OF CORAL REEFS
1.
Coastal
Protection
2.
Provides
Shelter
3.
Enhanced
Biodiversity
4.
Economic
Development
5.
Water
Filteration
6.
Provides
Nutrition
18. CAN WE RECOVER?
Recovery from bleaching can take weeks to months, but
recovered corals may grow slower and have reduced
fertility and productivity as compared to previously
unbleached corals.
If local stressors to coral reefs are reduced, the corals
have a better chance of recovering from an event such as
coral bleaching, making the reefs more resilient.
19. INITIATIVES TO PROTECT CORALS
International
Coral Reef
Initiative(ICRI)
Global Coral Reef
Monitoring
Network (GCRMN)
Coral Reef
Alliance
(CRA)
Coral Research and
Development
Accelerator
Platform(CoRDAP)
20. GOI launched
National Coastal
Mission Programme,
to protect and
sustain coral reefs
in the country.
INITIATIVES BY GOI
The Ministry of
Environment and
Forests and Climate
Change, India, has
included the studies
on coral reefs under
the Coastal Zone
Studies
The Zoological
Survey of India and
Forest Department,
Gujrat, has been
attempting to
restore coral reefs
using BIOROCKS.
21. Don't use chemically
enhanced pesticides and
fertilizers
Don't use chemically
enhanced pesticides and
fertilizers
HOW CAN WE HELP?
Don't pollute
Be an informed
consumer
Conserve Water
Reduce Greenhouse gas
emission