Types of coral reefs and its distribution

Coral reefs- its types and
distribution
Rehana Raj
DFK 1307
I Ph.D
College of Fisheries
Mangalore
jitenderanduat@gmail.com

Introduction
• Belong to the Phylum: Cnideria, Class: Anthozoa
• Under water structures made from CaCo₃
• Colonies of tiny animals called polyps or coral
polyps

• Polyp- like a tin can open at just one end; has
mouth surrounded by a ring of tentacles
• Have stinging cells or nematocysts
• Feeds on zooxanthellae

• Nematocysts help coral catch
food
• They also help protect the
coral
• When the cell is stimulated,
it releases a sharp barb
• The barb will fire and catch
the food and bring it back
towards the mouth jitenderanduat@gmail.com

• Symbiotic relationship
• Zooxanthella is an algae that lives in the skin of
coral
• Coral provides protection
• Zooxanthella provides food and color!

• Algae receive protection
and nutrients (carbon
dioxide, nitrogen and
phosphorus)
• Algae supply amino
acids, fatty acids, and
sugars to the corals.

• Principal organism- Hard corals
• Planula larvae settles down and attaches itself to
hard substrate
• Larvae develop into coral polyp

• Secrets calcium carbonate around its body
• Colony grows by asexual reproduction
• Some polyp develops gonads and able to
reproduce sexually

• Secretes hard exoskeleton- support and protect
their bodies
• Grow best in warm, shallow, sunny, clear, agitated
water
• Referred as ‘rainforests of the sea’- diverse
ecosystem

• Occupy less than 1% of the world ocean
surface
• Home for 25% of the all marine species
• Annual global economic value- US$ 375 billion

Zonation of coral reefs
• Reef front/ fore reef- on the
seaward side,rise of reefs
from lower depth of ocean to
just or just below the surface
of water
• Reef drop off- the slope of
this front forms a vertical wall

• Spur & groove formation-reef front
usually form a finger like arrangements;
breaks the wave energy & prevents the
damage
• Grooves are sand filled; allow sediment
to channel down & away from coral reefs

• Reef crest- highest point of reef
• Reef flat/ back reef-portion which is more
inward to land; area is having high variability,
made up of rocks, sand etc
• Reef ends at shoreline or descends into lagoon

Specific features
• Temperature: 26-27C
– Depth: Less than 80 ft to
230 feet
– Salinity: Normal salt levels
(35ppt)
– Light: Zooxanthellae need
light to survive
– Sedimentation: Being
covered with silt interferes
with photosynthesis
– Desiccation: being exposed
to air. The corals will die if
exposed too long
• Coral likes areas with lots of
waves:
– They are strong enough to
withstand the pressure
– New water means more food
– Waves remove silt
– New water brings more oxygen
300N and S of the equator

Types of coral reefs
• Fringing reef- directly attached to a
shore or borders it with an
intervening shallow channel or lagoon
Eg: Greater Caribbean region
• Barrier reef- separated from a
mainland or island shores by deep
channel or lagoon Eg: Great Barrier
Reef
• Atoll reef- more or less circular or
continuous barrier reefs extends all
the way around a lagoon without a
central island Eg: The Pacific Oceanjitenderanduat@gmail.com

Other reef types
• Patch reef-common, isolated, comparitively, small
reef usually within a lagoon or embayment; often
circular, surrounded by sand or seagrass
• Apron reef- short reef resembling a fringing reef,
but more sloped, extending out and downward
from a point or peninsular shore

• Bank reef- linear or semicircular shaped; larger
than patch reef
• Ribbon reef- long, narrow, possibly winding reef,
associated with an atoll lagoon
• Table reef-isolated atoll type without a lagoon

• Habili- Specific to red sea; does not reach the
surface, near enough to cause visible surf
• Cays- small, low elevation, sandy islands formed on
the surface of coral reefs from eroded material,
forms an area above sealevel

• Seamount or guyot- formed when coral reef
on volcanic islands subsides
• Top of seamount- rounded; guyots-flat

Hermatypic corals & Ahermatypic
corals
• Hermatypic corals- storny corals; obtain energy
from zooxanthella
• Secretes hard exoskeleton
• Have 6 or fewer lines of symmetry-hexacorallia or
zoantharia
• Scleractinia, Millepora, Tubipora and Heliopora

• Ahermatypic corals- have no zooxanthella, soft
corals
• have eight tentacles –octocorallia
• flexible, undulating in the current, and often are
perforated, with a lacy appearance
• skeletons are proteinaceousjitenderanduat@gmail.com

Distribution of coral reefs
• Estimated to cover 284300
km² (0.1% of ocean surface)
• Indo-pacific region (Red Sea,
Indian Ocean, Southeast Asia
& Pacific Ocean) -91.1%
• Southeast Asia accounts-32.3%
• Pacific including Australia
accounts-40.8%
• Atlantic and Caribbean corals
accounts- 7.6%
• Location of coral reef in
the world

Global distribution

Distribution of coral reefs in various
oceans
• Persian Gulf and Red Sea- contain a small
percentage of world’s coral reefs
• Indian Ocean-24% of the world’s coral reefs; occur
between the coastal lines of India and Srilanka
towards north, Thailand, Malaysia and Indonesia to
the NE, entrances to the Red Sea and Persian Gulf,
Yemen, Oman, Somalia northern Kenya and
Madagascar to the west and Australia to the east

• Southeast Asia- 30% of the world’s coral reefs;
from Philippines to western Indonesia
• Caribbean- 14% of the world’s coral reefs;
includes Caribbean Sea, Gulf of Mexico, South
Florida, the Bahamas and North Brazil

• Pacific Ocean Region- 25%
of the world’s coral reefs;
western Pacific supports
richest reef biota, include
Micronesia, Palau, Papua
New Guinea and Vanuatu
Distribution of coldwater and tropical coral
reefs

• Coral reefs are rare along west coast of Americas
and Africa- upwelling & strong cold coastal currents
• Seldom found along the coastline of South Asia
(eastern tip of India, Bangladesh & Myanmar);
northeastern coast of South America

Important coral reefs of the world
• Great barrier reef-largest, comprising over 2,900
individual reefs and 900 islands stretching for over
2,600 kilometers off Queensland, Australia
• The Mesoamerican Barrier Reef System—second
largest, stretching 1,000 kilometers from Isla Contoy
at the tip of the Yucatán Peninsula down to the Bay
Islands of Honduras

• The New Caledonia Barrier Reef—second
longest double barrier reef, covering 1,500
kilometers
• The Andros, Bahamas Barrier Reef-third
largest, following the east coast of Andros
Island, Bahamas, between Andros and Nassau

• The Red Sea-includes 6000-year-old fringing reefs
located around a 2,000 km coastline
• The Florida Reef Tract-largest continental US reef,
extends from Soldier Key, located in Biscayne Bay, to
the Dry Tortugas in the Gulf of Mexico
• Pulley Ridge-deepest photosynthetic coral reef,
Florida

• The Philippines coral reef area, the second largest in
Southeast Asia, is estimated at 26,000 square
kilometers and holds an extraordinary diversity of
species.
• The Raja Ampat Islands in Indonesia's West Papua
province offer the highest known marine diversity

Coral reefs in India
• Palk Bay
• The Gulf of Mannar
• Andaman and Nicobar Group of Islands.
• The Gulf of Kutch
• The Lakshadweep Islands

Importance of coral reefs
• Prevent sediments from washing up & damaging
the shoreline
• Act as physical barrier; creates healthier, protected
coastline habitat

• Sequesters CO₂, create an environment which
attract marine biodiversity
• Provides economic benefits
• Harvested for medicinal & jewellery purposes

• Critical habitats essential for the maintenance of
biodiversity.
• Tourism (generation of foreign exchange).
• Support fisheries.

References
• Biswas, K.P., Corals of Tropical Oceans, Daya
Publishing House 2008, pp 1-13
• www.wikipedia.org
• http://www.oceanworld.tamu
• http://www.com.univ
• http://www.marbef.org
• www.perf.org

Types of coral reefs and its distribution

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