Estes et al. 2011 paper discussion

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Discussion on the trophic downgrading of Planet Earth by Sofia Olivero Lora.

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Estes et al. 2011 paper discussion

  1. 1. Trophic Downgrading of Planet Earth Sofia Olivero Lora November 29, 2012 Estes et al. 2011
  2. 2. Mass extinction events (http://evolution.berkeley.edu)
  3. 3. (http://evolution.berkeley.edu)
  4. 4. 6th mass extinction• Early to middle stages• Differences – Homo sapiens – Loos larger-bodied animals in general, apex consumers in particular• Global occurrence
  5. 5. Apex consumers• Global and perpetual• Effects on processes – Carbon sequestration, invasive species, biogeochemical exchanges, etc.• Removal-trophic downgrading
  6. 6. Trophic cascade http://pubs.usgs.gov/fs/2010/3099/
  7. 7. http://www.ucc.ie/staff/memmers/Lough%20Hyne.htm
  8. 8. Alternative stable states• Sets of unique biotic and abiotic conditions• Basins of attraction – Set of individual conditions lead to long-time behavior – Collection of all possible initial conditions of a dynamical state• ASS- perturbations push ecosystem from one basin to another
  9. 9. Alternative stable states• Tipping points – Phase shifts – abrupt changes in ecosystem structure and function.• Hysteresis – Multiple states persist under equal environmental conditions – Example: Tropical cloud forests
  10. 10. Connectivity• Ecosystems are built around interaction webs• Every species can potentially influence many others• Interactions – Biological processes – Physicochemical processes – Highly complex network
  11. 11. Ecological Society of Americahttp://phys.org/news/2012-10-scientists-greenbelts-wildlife-sanctuaries.html
  12. 12. Trophic Downgrading• Not widely appreciated, difficult to observe• Need for perturbation, to be perceived• Time scales – When noticed, too late• Space scales
  13. 13. • Sea Otter (nutria) – Population collapse – -herbivorous sea urchins – +kelp abundance• Seastar – Prevents dominance mussels (mejillon)• Bass (robalo) – Reduce phytoplankton – Eats zooplanktivorous• Large reef fish – Fisheries (left)• Bass – Eats minnows – Promotes benthic algae
  14. 14. • Artic fox (zorro) – Eat seabirds – Reduces nutrients inputs from sea to land• Jaguar – Herbivore guild – Reduction plant recruitment and survival• Wolf – Elk (alce) browsing• Wildebeest (gorgon) – Rinderpest (virus) – Increase biomass-fire
  15. 15. • Kelp increase enhances abundance of kelp forest fish• Increases organic carbon- +growth rate of mussels• Gulls (gaviotas) – Fish- invertebrates• Fish, mammals, birds
  16. 16. Discussion• Management solution: restoration of apex consumers.• Ecological surprises – Pandemics, loss valuable sp., shifts ecosystem states, loss ES – Altered top-down regimes – Apex loss or introduction of exotics
  17. 17. Discussion• What about other anthropogenic threats?• Do present conservation strategies contemplate this new paradigm?
  18. 18. Surrogate species?Species used to represent other species or aspects of the environment to obtain a conservation objective. (Caro, 2010) Indicator Umbrella Keystone Flagship
  19. 19. Thanks for your attention!

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