CORAL REEFSCORAL REEFSReferences:References: Dr.Tim Flannery – We are the Weather Makers (2007 Australian of Dr.Tim Flannery – We are the Weather Makers (2007 Australian of the Year and Scientist at Macquarie Uni)the Year and Scientist at Macquarie Uni)Sydney AquariumSydney AquariumStacey and Lucas – Investigating GeographyStacey and Lucas – Investigating GeographyGBRMPA – web siteGBRMPA – web sitePaine – Macquarie Revision GuidesPaine – Macquarie Revision GuidesProfessor Ove Hoegh Guildberg, University of Queensland.Professor Ove Hoegh Guildberg, University of Queensland.

CoralCoralReefReef

EcosystemEcosystem

Coral Reefs are found where the Coral Reefs are found where the

following biophysical conditions existfollowing biophysical conditions exist:: Coral reefs occur where:Coral reefs occur where: - shallow areas in tropical latitudes- shallow areas in tropical latitudes, , oror where where warm ocean warm ocean

currents flowcurrents flow in temperate areas in temperate areas - a zone extending from Latitudes 30°N to 30°S of the equator;- a zone extending from Latitudes 30°N to 30°S of the equator; - - water depths from 2 to 30m water depths from 2 to 30m because they need light to allow because they need light to allow

the algae (zooxanthellae)the algae (zooxanthellae) to photosynthesise in the coral to photosynthesise in the coral - - warm waterswarm waters where the water temperature does not fall below where the water temperature does not fall below

17°C nor exceeds 34˚S with the optimum temperature being 17°C nor exceeds 34˚S with the optimum temperature being 26-27˚ for coral growth.26-27˚ for coral growth. - where - where waters are clear waters are clear and free of nutrients otherwise algae and free of nutrients otherwise algae

and slime will cover the coral and stop it photosynthesisingand slime will cover the coral and stop it photosynthesising - constant levels of - constant levels of high salinityhigh salinity - - high oxygen levels high oxygen levels where wave activity continually where wave activity continually

oxygenates the wateroxygenates the water - - low sediment levels low sediment levels as this will smother the coral and stop as this will smother the coral and stop

photosynthesisphotosynthesis

Global locations of large Global locations of large reef-building areas:reef-building areas:

- the - the Caribbean SeaCaribbean Sea, , - the western - the western Indian OceanIndian Ocean - the western reaches of the - the western reaches of the South PacificSouth Pacific. . - Non-tropical coral reef zones of :- Non-tropical coral reef zones of : (a) the (a) the Red Sea,Red Sea, where heat from the surrounding desert where heat from the surrounding desert climate warms the ocean and climate warms the ocean and (b) Australia's (b) Australia's Great Barrier Reef Great Barrier Reef which is warmed by a which is warmed by a tropical Pacific Ocean current.tropical Pacific Ocean current.

Location of Coral Reefs GloballyLocation of Coral Reefs Globally

The Great Barrier Reef The Great Barrier Reef – Spatial Pattern (where is it?)– Spatial Pattern (where is it?)

LOCATION: off the coast of LOCATION: off the coast of Queensland in northeast in northeast Australia from Latitude 8˚S to Latitude 24˚S stretching from Latitude 8˚S to Latitude 24˚S stretching from Papua New Guinea to Fraser Island. The World from Papua New Guinea to Fraser Island. The World Heritage area extends from Cape York to just north of Heritage area extends from Cape York to just north of BundabergBundaberg

SIZE: is the largest coral reef system in the world but iSIZE: is the largest coral reef system in the world but is s not one continuous reef but a series of not one continuous reef but a series of 2,900 individual 2,900 individual reefs and 600 islands that stretch for 2,300 kilometres reefs and 600 islands that stretch for 2,300 kilometres and covers an area of approximately 348,700 km².and covers an area of approximately 348,700 km².

SHAPE: it has four distinct regions Northern, Central, SHAPE: it has four distinct regions Northern, Central, Mackay and Southern ranging from the continental shelf Mackay and Southern ranging from the continental shelf to coral cays and islands.to coral cays and islands.

CONTINUITY: the northern section of the reef is older CONTINUITY: the northern section of the reef is older

(15 million years) and in the south younger (2million(15 million years) and in the south younger (2million). ).

Key WordsKey Words

Zooxanthellae – microscopic algae that Zooxanthellae – microscopic algae that live inside the coral polyplive inside the coral polyp

Symbiotic relationship – where two Symbiotic relationship – where two organisms benefit without damaging either organisms benefit without damaging either organismorganism

Spatial – where it is found?Spatial – where it is found?

location or distribution.location or distribution.

GLOBAL SPATIAL PATTERNS:GLOBAL SPATIAL PATTERNS: Worldwide coral reefs are estimated to cover 284,000 sq km Worldwide coral reefs are estimated to cover 284,000 sq km the largest area is in the Indo-Pacific region with 92% - of the largest area is in the Indo-Pacific region with 92% - of

this South East Asia accounts for 33% and Australia 41%; this South East Asia accounts for 33% and Australia 41%; the the Atlantic and and Caribbean coral reefs only account for 7.6% coral reefs only account for 7.6%

of the world totalof the world total Coral reefs are either restricted or absent from along the Coral reefs are either restricted or absent from along the

west coast of the west coast of the Americas, and the west coast of Africa due , and the west coast of Africa due to to cold ocean currentscold ocean currents that reduce water temperatures. that reduce water temperatures.

Corals are also absent from from Pakistan to Bangladesh Corals are also absent from from Pakistan to Bangladesh and the coast around north-eastern South America and and the coast around north-eastern South America and Bangladesh due to the release of Bangladesh due to the release of vast quantities of vast quantities of freshwaterfreshwater from the Amazon and Ganges Rivers from the Amazon and Ganges Rivers

Coral reefs are one of most biodiverse Coral reefs are one of most biodiverse ecosystems in the worldecosystems in the world

although located in nutrient-poor tropical although located in nutrient-poor tropical waters the process of nutrient cycling waters the process of nutrient cycling between corals, the zooxanthellae, and between corals, the zooxanthellae, and other reef organisms explains why coral other reef organisms explains why coral reefs flourish as the recycling ensures that reefs flourish as the recycling ensures that fewer nutrients are needed overall to fewer nutrients are needed overall to support the communitysupport the community

The GBR has the richest fauna The GBR has the richest fauna biodiversity on the planetbiodiversity on the planet

Over 2000 fish speciesOver 2000 fish species 500 coral species500 coral species 300 hard coral species300 hard coral species Over 400 sponge speciesOver 400 sponge species 4000 molluscs species4000 molluscs species 23 species of marine mammals23 species of marine mammals 11 species sea snakes11 species sea snakes 6 species of turtles6 species of turtles 215 species of birds215 species of birds Migrating whalesMigrating whales

Conditions necessary for Coral Conditions necessary for Coral Reefs to grow:Reefs to grow:

Corals are animals related to jellyfish. They haveCorals are animals related to jellyfish. They have

microscopic algae called zooanthellae whichmicroscopic algae called zooanthellae which

photosynthesise living inside their tissues in a symbioticphotosynthesise living inside their tissues in a symbiotic

relationship. Therefore, Corals need the following:relationship. Therefore, Corals need the following: Shallow water 2 to 30 metres so photosynthesis can occurShallow water 2 to 30 metres so photosynthesis can occur Warm ocean temperatures 20-35˚C (ideally 26 to 27˚C) to build Warm ocean temperatures 20-35˚C (ideally 26 to 27˚C) to build

limestonelimestone Clear water low in nutrients. Nutrients such as phosphates and nitrogen Clear water low in nutrients. Nutrients such as phosphates and nitrogen

increase algae growth and will smother corals.increase algae growth and will smother corals. Constant high salinity Constant high salinity High oxygen levels where wave action oxygenates the waterHigh oxygen levels where wave action oxygenates the water Low sediment levels as silt will smother the algae and stop Low sediment levels as silt will smother the algae and stop

photosynthesis occurring.photosynthesis occurring.

Natural stresses on the GREAT Natural stresses on the GREAT BARRIER REEFBARRIER REEF

Cyclones Cyclones – breaks off coral, changes salinity of the water column, – breaks off coral, changes salinity of the water column, turns over the water column to lessen warm water in upper layer turns over the water column to lessen warm water in upper layer and reduces global warming threatand reduces global warming threat

Marine organisms Marine organisms – burrowing, boring and breaking– burrowing, boring and breaking Predators Predators - Crown of Thorns Star Fish – native top predator kills - Crown of Thorns Star Fish – native top predator kills

the coral– dependant on currents and water temperature for larvae the coral– dependant on currents and water temperature for larvae to spreadto spread

Sea Level change Sea Level change – 15,000 years ago sea level was lower forcing – 15,000 years ago sea level was lower forcing corals to die and re-colonise new areascorals to die and re-colonise new areas

Flooding and runoff from mainland Flooding and runoff from mainland – can affect salinity levels and – can affect salinity levels and carry sediment into the reef systemcarry sediment into the reef system

Subsidence and continental drift Subsidence and continental drift has affected where corals has affected where corals colonise over the last 15 million yearscolonise over the last 15 million years

Value of Coral Reefs:Value of Coral Reefs:

Coral reefs yield around US$30 billion in Coral reefs yield around US$30 billion in income each year mostly to people in income each year mostly to people in developing nationsdeveloping nations

One in four organisms in the ocean One in four organisms in the ocean spends part of its life in coral reefsspends part of its life in coral reefs

Threats to Coral Reefs:Threats to Coral Reefs:GLOBALLY GLOBALLY Coral Bleaching episodes due to climate change Coral Bleaching episodes due to climate change Sea level change due to global warming occurring around Pacific Sea level change due to global warming occurring around Pacific

Islands will affect depth of coral growthIslands will affect depth of coral growth Over fishing including dynamite fishing and cyanide fishing in Over fishing including dynamite fishing and cyanide fishing in

poorer countries and illegal fishing of endangered speciespoorer countries and illegal fishing of endangered species Algal Blooms from nutrient runoffAlgal Blooms from nutrient runoff Fisheries – trawling; aquaculture – nutrient waste; Fisheries – trawling; aquaculture – nutrient waste; Tourism – anchor damage, litter, touching, souvenirs, sewage from Tourism – anchor damage, litter, touching, souvenirs, sewage from

resorts and boats, hand feeding changes feeding habits, resorts and boats, hand feeding changes feeding habits, development on islands, moorings,development on islands, moorings,

Shipping – oil spills, sewage, litter, anti fouling agents on hullsShipping – oil spills, sewage, litter, anti fouling agents on hulls Agriculture and logging activities creating increased silt and Agriculture and logging activities creating increased silt and

nutrient runoff particular problems in South East Asianutrient runoff particular problems in South East Asia Introduced speciesIntroduced species Acidification of the oceans due to increasing CO2 which when Acidification of the oceans due to increasing CO2 which when

dissolved lowers pH and weakens carbonate ions in coral and dissolved lowers pH and weakens carbonate ions in coral and shellfish.shellfish.

GREAT BARRIER REEF THREATSGREAT BARRIER REEF THREATS Crown of Thorn Starfish damage due to food chain disturbance – Crown of Thorn Starfish damage due to food chain disturbance –

increased nutrient runoff and warming oceans allowing more larvae increased nutrient runoff and warming oceans allowing more larvae to surviveto survive

Road building - in 1982 controversy over unsealed road built in Road building - in 1982 controversy over unsealed road built in Daintree rainforest Qld caused silt runoff onto coral reef/one of only Daintree rainforest Qld caused silt runoff onto coral reef/one of only two places in the world where coral reefs live next to rainforest – two places in the world where coral reefs live next to rainforest – caused political issue/campaigns and ultimate protection of Daintree caused political issue/campaigns and ultimate protection of Daintree as World Heritage Wet Tropical Rainforest Areaas World Heritage Wet Tropical Rainforest Area

Acidification of the water causing brittleness of coral due to warming Acidification of the water causing brittleness of coral due to warming oceansoceans

Extinctions and threats to endangered species eg. Green turtle Extinctions and threats to endangered species eg. Green turtle protected – once processed into soup; protected – once processed into soup;

TourismTourism Runoff of silt and nutrients from fertilizers from farmsRunoff of silt and nutrients from fertilizers from farms Global WarmingGlobal Warming

The Great Barrier Reef and climate The Great Barrier Reef and climate change:change:

Is the most vulnerable reef in the world to climate Is the most vulnerable reef in the world to climate change change

42% was bleached in 1988 42% was bleached in 1988 18% suffered permanent damage18% suffered permanent damage 2002 90% all inshore corals killed by ocean warming2002 90% all inshore corals killed by ocean warming 2006 coral bleaching avoided due to Cyclone Larry 2006 coral bleaching avoided due to Cyclone Larry

which mixed the warm top layers of the ocean with the which mixed the warm top layers of the ocean with the cooler water below (water column mixed) however cooler water below (water column mixed) however 50,000 homes in Queensland destroyed, crops wiped 50,000 homes in Queensland destroyed, crops wiped out and people killed.out and people killed.

Coral Reefs in the future:Coral Reefs in the future:

Coral reef scientists warn that :Coral reef scientists warn that : 11°C rise in global temperature will cause °C rise in global temperature will cause

82% of GBR to bleach and die82% of GBR to bleach and die 2°C rise in temperature will bleach 97% 2°C rise in temperature will bleach 97%

reefsreefs 3°C rise will cause total devastation3°C rise will cause total devastation

Latest NewsLatest News

Cargo ship's oil spill threatens wildlife 12/3/09A cocktail of 650 tonnes of fuel and fertiliser has been lost from a cargo ship caught in fierce seas from cyclone Hamish off the south-east Queensland coast, potentially threatening wildlife

Location of Location of Great Barrier Great Barrier

ReefReef