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CORAL REEFS

CORAL REEFS. Secondary Sources (Evidence) used: Dr.Tim Flannery – We are the Weather Makers (2007 Australian of the Year and Scientist at Macquarie Uni) Sydney Aquarium Stacey and Lucas – Investigating Geography GBRMPA Paine – Macquarie Revision Guides. Spatial patterns and dimensions:.

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CORAL REEFS

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  1. CORAL REEFS Secondary Sources (Evidence) used: Dr.Tim Flannery – We are the Weather Makers (2007 Australian of the Year and Scientist at Macquarie Uni) Sydney Aquarium Stacey and Lucas – Investigating Geography GBRMPA Paine – Macquarie Revision Guides

  2. Spatial patterns and dimensions: • Coral reefs are located in: - shallow areas in tropical latitudes, or where warm ocean currents flow in temperate areas - a zone extending at most from 30°N to 30°S of the equator; - reef-forming corals do not grow at depths of over 30 m so as light can penetrate allowing the algae and plankton to work together to photosynthesise in the coral - warm waters where the water temperature falls below 16 °C

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

  4. The Great Barrier Reef • is the largest coral reef system in the world • It is not one continuous reef but a series of reefs of roughly 3,000 individual reefs and 900 islands that stretch for 2,600 kilometres and cover an area of approximately 344,400 km². • The reef is located off the coast of Queensland in northeast Australia from……

  5. Worldwide coral reefs are estimated to cover 284,000 sq km • the Indo-Pacific region has 92% - of this South East Asia accounts for 33% and Australia 41%; • the Atlantic and Caribbean coral reefs only account for 7.6% of the world total • Coral reefs are either restricted or absent from along the west coast of the Americas, and the west coast of Africa due to cold ocean currents that reduce water temperatures. • Corals are also absent from from Pakistan to Bangladesh and the coast around north-eastern South America and Bangladesh due to the release of vast quantities of freshwater from the Amazon and Ganges Rivers

  6. Coral reefs one of most biodiverse ecosystems in the world • although they are located in nutrient-poor tropical waters the process of nutrient cycling between corals, zooxanthellae, and other reef organisms provides an explanation for why coral reefs flourish as the recycling ensures that fewer nutrients are needed overall to support the community

  7. Biophysical interactions: * weather and climate* geomorphic and hydrologic processes* weathering, erosion, transportation, deposition* invasion, succession, modification, resilience* adjustments and responses to natural stress * food webs, food chains.

  8. Producers • Producers are the base of the food chain and are very important because all of the energy in the community flows from them. On coral reefs there are three major types of producers: •  Cyanobactera or blue-green algae • These species also fix nitrogen and  enhance nutrient availability •  Seaweeds • These include both conspicuous macro-algae and the less conspicuous but very abundant turf algae. Seaweeds are heavily grazed by herbivores  •  Reef-building or hematypic corals • Corals are producers due to tiny plants that live inside their bodies called zooxanthellae • Benefits of Zooxanthellae to coral • Benefits of coral to zooxanthellae • removes coral waste • provides nutrients to the coral • accelerates coral skeleton growth • provides safe place to live • lets sunlight through to zooxanthellae • provides abundant nutrients from waste • Thus, corals are producers because the zooxanthellae provide nutrients via photosynthesis to the corals. As a result, many corals live entirely off of sunlight.

  9. Natural stresses on the GREAT BARRIER REEF • Cyclones – breaks off coral, changes salinity of the water column, turns over the water column to lessen warm water in upper layer and reduces global warming threat • Marine organisms – burrowing, boring and breaking • Predators - Crown of Thorns Star Fish – native top predator kills the coral– dependant on currents and water temperature for larvae to spread • Sea Level change – 15,000 years ago sea level was lower forcing corals to die and re-colonise new areas • Flooding and runoff from mainland – can affect salinity levels and carry sediment into the reef system • Subsidence and continental drift has affected where corals colonise over the last 15 million years

  10. Value of Coral Reefs: • Coral reefs yield around US$30 billion in income each year mostly to people in developing nations • One in four organisms in the ocean spends part of its life in coral reefs

  11. Human Impacts - Threats to Coral Reefs: 1. GLOBALLY • Coral Bleaching episodes due to climate change • Sea level change due to global warming occurring around Pacific Islands will affect depth of coral growth • Over fishing including dynamite fishing and cyanide fishing in poorer countries and illegal fishing of endangered species • Algal Blooms from nutrient runoff • Fisheries – trawling; aquaculture – nutrient waste; • Tourism – anchor damage, litter, touching, souvenirs, sewage from resorts and boats, hand feeding changes feeding habits, development on islands, moorings, • Shipping – oil spills, sewage, litter, anti fouling agents on hulls • Agriculture and logging activities creating increased silt and nutrient runoff particular problems in South East Asia • Introduced species

  12. 2. GREAT BARRIER REEF THREATS • Crown of Thorn Starfish damage due to food chain disturbance – increased nutrient runoff and warming oceans allowing more larvae to survive • Road building - in 1982 controversy over unsealed road built in Daintree rainforest Qld caused silt runoff onto coral reef/one of only two places in the world where coral reefs live next to rainforest – caused political issue/campaigns and ultimate protection of Daintree as World Heritage Wet Tropical Rainforest Area • Acidification of the water and increasing brittleness of coral due to warming oceans • Extinctions and threats to endangered species eg. Green turtle protected – once processed into soup; • Tourism • Runoff of silt and nutrients from fertilizers from farms • Global Warming

  13. The Great Barrier Reef and climate change: • Is the most vulnerable reef in the world to climate change • 42% was bleached in 1988 • 18% suffered permanent damage • 2002 90% all inshore corals killed by ocean warming • 2006 coral bleaching avoided due to Cyclone Larry which mixed the warm top layers of the ocean with the cooler water below (water column mixed) however 50,000 homes in Queensland destroyed, crops wiped out and people killed.

  14. Coral Reefs in the future: • Coral reef scientists warn that : • 1°C rise in global temperature will cause 82% of GBR to bleach and die • 2°C rise in temperature will bleach 97% reefs • 3°C rise will cause total devastation

  15. Traditional and Contemporary Management Strategies:

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