Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

Coral reefs group 8


Published on

Published in: Technology, Lifestyle
  • Be the first to comment

Coral reefs group 8

  1. 1. CORAL REEFS Often called “rainforests of the sea”, they are one of the most diverse ecosystems on Earth. They occupy less than 0.1% (around 284,300 km2) of the worlds ocean surface, yet provide a home for 25% of all marine species, includingfish, mollusks, worms, crustaceans, echinoderms, sponges , and other cnidarians. They are most commonly found at shallow depths in tropical waters. Coral colonies thrive at 21-29OC, saline environments, and clear waters.
  2. 2. LOCATIONIndo-Pacific region (including the Red Sea, Indian Ocean, Southeast Asia and the Pacific) account for 91.9%.
  4. 4. A fringing reef can taketen thousand years toform, and an atoll can take up to 30 million years.
  5. 5. STRUCTURE Corals are modular animals, anemone-like cylindrical polyps with prey-capturing tentacles surrounding the opening or mouth. Most form sessilecolonies supported on the tops of dead colonies and cease growth when they reach the surface of the water Coralline algae are important contributors to reef structure in those parts of the reef subjected to the greatest forces by waves. These algae strengthen the reef structure by depositing limestone in sheets over the reef surface.
  6. 6. General abiotic conditions: Shallow waters, Temperature 21-29 C, Clear low-nutrient waters, salinity 30-40 ppt. However, the coral reef can be divided into different zones with varyingabiotic characteristics and consequently different biological communities. The environmental factors responsible for these differences are wave action, current direction and intensity, light intensity, etc. Light sets the depth at which zooxanthellae can survive. Diversity is lowest at the crest near the surface, where only species such as massive pillar- shaped corals tolerant of intense or frequent disturbance of waves cansurvive. Diversity increases with depth to a maximum of about 20 m. Then it decreases as light attenuates, eliminating shade-intolerant species.
  7. 7. Branching corals occur along the reef crest where abundant light drives photosynthesis needed to support rapid growth. Vigorouswave energy clears sediment fromthe branching species that have no biological means of sediment removal. Further down the reef front, slower-growing hemispherical corals (Mixed/Massive) are better suited for removing sediment coming down the slope. In even deeper water, platelike colonies respond to continually decreasing light levels. This shape places all the polyps on upward- facing surfaces, optimizing the colonys ability to gather light— much like solar panels.
  8. 8. Adding to the productivity of the coral reefs are crustose, coralline algae, turf algae, macroalgae, sea grass, sponges, phytoplankton, and a large bacterial population. Coral reefs are among the most highly productive ecosystems on earth.This productivity and the varied habitats within the reef support a high diversity of life –thousands of kinds of invertebrates (some of which, such as sea urchins, feed on coral animals and algae), many kinds of herbivorous fish that graze on algae, and hundreds of predatory species. Some of these predators such as the puffers and filefish, are corallivores, feeding on coral polyps. Others lie in ambush for prey in coralline caverns. In addition, there is a wide array ofsymbionts such as cleaning fish and crustaceans that pick parasites and detritus from larger fish and invertebrates.
  9. 9. Threats to Coral Reefs Natural and Human
  10. 10. REEFS WORLDWIDE ARE THREATENED• 11% of reefs have been lost• 16% of reefs severely damaged• ~60% of studied reefs threatened by human activities• No pristine reefs left
  11. 11. Threats to coral and coral reefs: • 1) Natural • 2) Anthropogenic –of human origin
  12. 12. Natural disturbances that affect corals and coral reefs? • Hurricanes • Tsunamis • Volcanoes • Earthquakes • Predators & competitors • Bleaching • Pathogens
  13. 13. Hurricanes• Physical damage• Smothering• Freshwater poisoning• Destruction of other ecosystems upon which coral reefs depend
  14. 14. Tsunamis• Physical damage• Erosion• Possible disruption of reproduction and recruitment
  15. 15. Volcanoes• Depends upon where volcano occurs• Heat• Smothering and sedimentation
  16. 16. Earthquakes• Little direct impact• Indirect impacts -triggers tsunamis -coastal landslides
  17. 17. Predators• crown of thorns starfish• snails• parrotfish• butterflyfish
  18. 18. Crown of Thorns Starfish
  19. 19. Coral-eating Snails
  20. 20. Competitors • algae
  21. 21. • Loss of zooxanthellae• causes – higher than usual ocean temperature – sharp changes in salinity – heavy UV light exposure
  22. 22. Pathogens• Diseases on the rise – new pathogens (8+) – land pathogens (Aspergillus) – occurring at all depths – More susceptible when stressed
  23. 23. Threats from Nature• Unusually strong waves such as those from a hurricane• Water temperature changes• Dramatic changes in saltiness of water• Predators, such as snails and crown of thorns starfish• Overgrowth of algae
  24. 24. Threats to coral and coral reefs: • 1) Natural • 2) Anthropogenic –of human origin
  25. 25. Anthropogenic threats to coral reefs:• Overfishing• Development• Mining and dredging• Recreation
  26. 26. Overfishing• Ecological imbalance
  27. 27. Overfishing• Ecological imbalance
  28. 28. Overfishing• Destructive fishing practices
  29. 29. Development• Sediment smothering• Freshwater input• Pollutants & nutrients (sewage, pesticides, fertilizer, heavy metals, pathogens)
  30. 30. Development
  31. 31. Development
  32. 32. Pollution
  33. 33. Power Plants
  34. 34. Mining for construction materials and dredging• Destruction of reef structure• Stirs up sediment
  35. 35. RecreationAnchors, boats, flippers, hands, feet•Kill animal tissue•Skeleton breakage
  36. 36. Threats from Humans• Pollution – Sediments block light from zooxanthellae – Chemicals either poison corals or allow too much algae to grow• Power plants – Filter water and kill fish and plankton – Releasing hot water kills organisms
  37. 37. More Threats from Humans• Deforestation – Causes erosion which clouds the water – Burning of trees could be a factor in climate change• Destructive fishing – Blasting with dynamite – Cyanide poison – Boats running aground, anchors – Overfishing
  38. 38. Synergistic effects• interaction of natural changes & human activity• multiple insults
  39. 39. Global climate change• Reduced reef building• Increase in frequency and intensity of hurricanes• Increases in bleaching• Increased in disease
  40. 40. A New Home• Corals now have a choice of where to live• Corals are very sensitive and are rapidly dying• People are trying to help by creating artificial reefs
  41. 41. Arguments for Artificial Reefs• It can help build or rebuild a reef• It will increase fish populations by making new habitats
  42. 42. Arguments Against Artificial Reefs• Moveable• Chemical leaking and leaching into the ocean• It does not increase fish populations but rather moves them to one location away from their natural habitat which makes them easier to catch
  43. 43. The Great Barrier Reef
  44. 44. Tubbataha Reef
  45. 45. It’s up to Us to Save Coral Reefs Be Responsible.