Roff and Mumby 2012 Discussion


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A discussion on the global disparity in the resilience of coral reefs by Shweta Sharma.

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Roff and Mumby 2012 Discussion

  1. 1. Global disparity in the resilience of coral reef
  2. 2. Author George Roff and Peter J. Mumby Presented by Shweta Sharma
  3. 3. Introdution  What is resilience ?  Why coral reef is one of the most intensively studied system in context of resilience ?  Coral reef resilience and geographic bias.  The two major biogeographic provinces of coral reef 1. The caribbean 2. Indo-Pacific
  4. 4. Great caribbean coral reef Deep water coral
  5. 5. Great caribbean coral reef 5 Meter Reef Coral
  6. 6. Indo-Pacific Corals
  7. 7. Indo-Pacific Coral
  8. 8. Differences in the recovery and state of Caribbean versus Indo-Pacific reefs      Indo-Pacific and Caribbean reefs differ in many ways. 1) Faunal composition, Grazing pressure 2) Greater niche partitioning of herbivore in the Indo-Pacific while herbivore biomass in the Caribbean lies below potential carrying capacity. 3) Species richness(Acanthudidae), Coral reproductive trait 4) Ecological resilience capacity 5) Greater proportion of macroalgal dominance and a higher severity of phase shift in the caribbean than in the Indo- Pacific.
  9. 9. Differences in the recovery and state of Caribbean versus Indo-Pacific reefs     Indo-Pacific and Caribbean differ in many ways. Caribbean reef shows decline of trajectories, with no observation of recovery following disturbance . 46% of reef in Indo-Pacific have showed evidence of recovery following disturbance. 83% of Caribbean reefs exhibited either no recovery(47%) or no decline 36%. 39% of Indo-Pacific reef exhibited either no recovery(24%) or no decline(15%).
  10. 10. Bar Graph showing Recovery, No decline, No recovery of coral reef
  11. 11. Graph showing macroalgal dominance
  12. 12. Biodiversity-based hypotheses  Hypotheses 1  Loss of fast-growing Acropora corals in the Caribbean are responsible for low resilience of coral in this region.  1) Two categories of corals I) Fast-growing branching corals from families Acroporidae and Pocilloporidae capable of extending > 100 mm per year.  II) Slow-growing corals capable of extending<50 mm per year.
  13. 13. Biodiversity-based hypotheses  Hypothesis 2 Higher diversity and greater functional redundancy of herbivores in the Indo-Pacific than in caribbean.  1) Elevated herbivore diversity can increase reef resilience by providing greater niche diversification and creating functional redundancy.  2) Burkepile and Hay found that two complementary herbivore species were more effective in mitigating algal bloom than was a single species
  14. 14. Biodiversity-based hypotheses  3) There is striking difference in the species and generic richness in Caribbean and Indo-Pacific.  a) Of the 88 species and six genera of Acanthuridae that inhabit in the Indo-Pacific and Caribbean regions,  Caribbean have only four species represented by a single genus(Acanthurus).  b) Caribbean lacks acanthurids of the genus Naso, some of which consume the largest of reef macrophyte sargassum spp.
  15. 15. Bottom-up hypotheses Macroalgae bloom faster in the Caribbean
  16. 16. Bottom-up hypothesis
  17. 17. Bottom-up hypotheses  Hypothesis 3  Higher adult stock of macro algae on Caribbean reefs imply higher rate of algal recruitment in this region.  1) Speed of algal bloom is high where herbivory is intense so this finding leads to fourth hypothesis.  Hypothesis 4  Various anthropogenic activity like land cultivation, deforestation, producing nutrients, and nutrient supply from terrestrial sources might be higher in Caribbean leading to Coral algal phase shift.
  18. 18. Bottom-up hypotheses  Hypothesis 5  Nutrient nitrogen and phosphorus helps in algal growth but it growth is limited by various metals e.g iron. Algal growth is less limited in the Caribbean due to increase in Aeolian dust a good source of iron , resulting increase in algal bloom when other enabling condition are met.
  19. 19. Top-down hypotheses Hypothesis 6  Herbivore biomass is greater in Indo-Pacific than in Caribbean creating higher absolute grazing pressure in Indo- Pacific 1)Total herbivores fish biomass in the Indo-Pacific averaged 29.0gm-2 while Caribbean have 9.25gm-2. 2) Parrotfish biomass in the Indo-Pacific was nearly twice that of the Caribbean. (13.12gm-2 VS 6.7 gm-2) 3) Biomass of surgeonfish is more than fourfold higher in the Indo-Pacific than in the Caribbean( 11.61gm-2VS2.56gm-2) and maximum biomass found 12 fold higher in the Indo-Pacific than in the Caribbean.
  20. 20. Conclusion  Indo-Pacific reef have greater capacity of resilience than the Caribbean.  Algal bloom occur more readily in the Caribbean .  Disease that resulted in loss of both fast growing coral, are responsible for present state of the caribbean.  Referances:- Roff, G., & Mumby, P. J. (2012). Global disparity in the resilience of coral reefs.Trends in ecology & evolution, 27(7), 404-413.
  21. 21. Thanks