1. Systematic effects of fishing on global coral reef herbivore populations Clinton Edwards, Scripps Institution of Oceanography Co-Authors: Jennifer E. Smith, Stuart A. Sandin, Brian Zgliczynski, Alan Friedlander, Ivor Williams, Alison Green, Hugh Sweatman, Marah Hardt

2. The problem…

3. Causes of reef decline… Global Stressors: Local Stressors: WarmingAcidificationTropical Storms OverfishingPollutionCoastal Development

4. Top-down influence of herbivory Williams (2001), Friedlander et al. (2007) Biomass g m-2 Caribbean Pacific Herbivore biomass and macroalgal cover are negatively correlated

5. Top-down influence of herbivory Smith et al (2010), Burkepile et al (2006) Experimental herbivore removal consistently leads to an increase in fleshy algae

6. Lower biomass, fewer numbers and smaller sized herbivores in fished areas Evidence for exploitation Friedlander (2004) (Protected)(Fished)

7. Herbivores are important for healthy reef structure & function But… – What is the global status of coral reef herbivorous fish populations? – Is there evidence for fishing effects? – Are different feeding guilds affected differently? The need for research

8. Browsers Grazer / Detritivores Functional subgroups are based on different feeding modes Different feeding modes result in variable impacts to the reef matrix Herbivore functional groups Territorial Damselfish Scraper / Small Excavators Photo: Minguell, C. Photo: Rainer Kretzberg Photo: Jen Smith

9. Herbivore density project Our Goals: 1.Identify natural levels of herbivore populations on pristine reefs and document variability 2.Determine evidence for fishing effects 3.Determine exploitation effects on functional groups Methods: Develop a comprehensive database of worldwide herbivore biomass/abundance levels Systematic literature review Governmental and other monitoring programs: CRED, TNC, AIMS

10. Institute for Scientific Information (ISI) Web of Science database 1980-2011 Search terms= herbiv*, biomass, abundance, herbiv* and assemblage, etc. Qualitative or quantitative description of depth, reef zone (fore reef, reef crest, etc.) and reef type (barrier reef, atoll, etc.) Site location information and time period of study Rigorous and peer reviewed method for evaluating fish biomass and/or abundance (SPC or belt) Report abundance and/or biomass means of all major herbivorous fishes found in the study area Fisheries accessibility Unpublished monitoring datasets were subject to the same criteria Methods: data collection

11. Methods: fisheries accessibility Fisheries accessibility was designated based upon human habitation, isolation and level of protection at each site where surveys were conducted Two levels of fishing activity “not fisheries accessible” (NFA) “fisheries accessible” (FA)

12. Methods: analysis (i)Global means of biomass and abundance for NFA and FA areas (ii)Differences between NFA and FA locations within regions (iii)Functional group analysis

13. Results: data collection 300+ studies from search criteria Only 75 studies meet full criteria Unpublished datasets from Indonesia, Pacific Islands, Caribbean, Hawaii, GBR & Indian Ocean 2706 site level estimates of biomass and abundance from 145 locations

14. Results: overall biomass & abundance NFAFA NFAFA Not Fisheries Accessible (NFA) Fisheries Accessible (FA)

15. Results: regional effects of fishing

16. Results: world-wide island level herbivore biomass

17. Results: functional group biomass

18. Over-exploitation of fish resources has large impacts on herbivorous fish assemblages Fisheries accessibility changes the size structure of the herbivores guild; fished reefs are dominated by relatively abundant and smaller individuals Herbivore biomass has declined in most regions; biomass levels as high as >100g m -2 are found on many unfished reefs Fisheries accessible reefs have altered functional group structure Management schemes should take into consideration natural levels of the different functional groups of herbivores Conclusions

19. Over-exploitation of fish resources has large impacts on herbivorous fish assemblages Fisheries accessibility changes the size structure of the herbivores guild; fished reefs are dominated by relatively abundant and smaller individuals Herbivore biomass has declined in most regions; biomass levels as high as >100g m -2 are found on many unfished reefs Fisheries accessible reefs have altered functional group structure Management schemes should take into consideration natural levels of the different functional groups of herbivores Conclusions

20. Over-exploitation of fish resources has large impacts on herbivorous fish assemblages Fisheries accessibility changes the size structure of the herbivores guild; fished reefs are dominated by relatively abundant and smaller individuals Herbivore biomass has declined in most regions; biomass levels as high as >100g m -2 are found on many unfished reefs Fisheries accessible reefs have altered functional group structure Management schemes should take into consideration natural levels of the different functional groups of herbivores. Conclusions

21. Over-exploitation of fish resources has large impacts on herbivorous fish assemblages Fisheries accessibility changes the size structure of the herbivores guild; fished reefs are dominated by relatively abundant and smaller individuals Herbivore biomass has declined in most regions; biomass levels as high as >100g m -2 are found on many unfished reefs Fisheries accessible reefs have altered functional group structure Management schemes should take into consideration natural levels of the different functional groups of herbivores Conclusions

22. Over-exploitation of fish resources has large impacts on herbivorous fish assemblages Fisheries accessibility changes the size structure of the herbivores guild; fished reefs are dominated by relatively abundant and smaller individuals Herbivore biomass has declined in most regions; biomass levels as high as >100g m -2 are found on many unfished reefs Fisheries accessible reefs have altered functional group structure Management schemes should take into consideration natural levels of the different functional groups of herbivores Conclusions

23. Collaborators & Contributors: Jennifer Smith Stuart Sandin Alan Friedlander Ivor Williams Alisson Green Brian Zgliczynski Marah Hardt Hugh Sweatman Australian Institute of Marine Science (AIMS) NOAA Coral Reef Ecosystem Division (CRED) The Nature Conservancy (TNC) CAMEO (funding); NSF & NOAA Thank you also…. Levi Lewis, Emily Kelly, Nichole Price Andrew Lukosus The entire Smith-Sandin academic-industrial-complex!!! Thank You!!

24. For more information about this work and the other fascinating topics of research being conducted by myself and my colleagues please visit the Coral Reef Systems booth (I will be there from 8-10 Tue/Thurs) Come see us!!!