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Ecosystem-Scale Effects of Nutrients and Fishing on Coral Reefs

DOI: 10.1155/2011/187248

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Nutrient pollution and fishing are the primary local causes of coral reef decline but their ecosystem-scale effects are poorly understood. Results from small-scale manipulative experiments of herbivores and nutrients suggest prioritizing management of fishing over nutrient pollution because herbivores can control macroalgae and turf in the presence of nutrients. However, ecological theory suggests that the opposite occurs at large scales. Moreover, it is unclear whether fishing decreases herbivores because fishing of predators may result in an increase in herbivores. To investigate this paradox, data on the fish and benthic communities, fishing, and nutrients were collected on Kiritimati, Kiribati. Oceanographic conditions and a population resettlement program created a natural experiment to compare sites with different levels of fishing and nutrients. Contrary to theory, herbivores controlled macroalgae in the presence of nutrients at large spatial scales, and herbivores had greater effects on macroalgae when nutrients were higher. In addition, fishing did not increase herbivores. These results suggest that protecting herbivores may have greater relative benefits than reducing nutrient pollution, especially on polluted reefs. Reallocating fishing effort from herbivores to invertivores or planktivores may be one way to protect herbivores and indirectly maintain coral dominance on reefs impacted by fishing and nutrient pollution. 1. Introduction Fishing [1–7] and nutrient pollution [8, 9] or both [10–14] are cited as the most important local causes of coral reef decline. It is difficult, however, to evaluate local fishing and nutrient effects independently because these factors are almost always confounded and large-scale experiments are infeasible. Results from theoretical and small-scale experimental studies (typically <1?m2, four from 50 to 250?m2 [14]) suggest prioritizing management of herbivore populations because herbivores can control the effect of nutrients on macroalgal and turf abundance and nutrient enrichment alone is not sufficient to cause a phase shift from coral to macroalgal and/or turf algal dominance [11, 14, 15]. In order to apply these results and implement ecosystem-based management, information is needed on (1) how fishing and nutrients interactively affect the fish and benthic communities, (2) the mechanisms by which fishing (rather than cages that exclude fish) and nutrients are linked to shifts to macroalgal and turf algal dominance, and (3) whether herbivores can control macroalgae and turf algae when nutrient enrichment


[1]  S. Jennings, E. M. Grandcourt, and N. V. C. Polunin, “The effects of fishing on the diversity, biomass and trophic structure of Seychelles' reef fish communities,” Coral Reefs, vol. 14, no. 4, pp. 225–235, 1995.
[2]  A. M. Friedlander and E. E. DeMartini, “Contrasts in density, size, and biomass of reef fishes between the northwestern and the main Hawaiian islands: the effects of fishing down apex predators,” Marine Ecology Progress Series, vol. 230, pp. 253–264, 2002.
[3]  J. M. Pandolfi, R. H. Bradbury, and R. H. Bradbury, “Global trajectories of the long-term decline of coral reef ecosystems,” Science, vol. 301, no. 5635, pp. 955–958, 2003.
[4]  N. K. Dulvy, R. P. Freckleton, and N. V. C. Polunin, “Coral reef cascades and the indirect effects of predator removal by exploitation,” Ecology Letters, vol. 7, no. 5, pp. 410–416, 2004.
[5]  M. J. H. Newman, G. A. Paredes, E. Sala, and J. B. C. Jackson, “Structure of Caribbean coral reef communities across a large gradient of fish biomass,” Ecology Letters, vol. 9, no. 11, pp. 1216–1227, 2006.
[6]  K. Newton, I. M. C?té, G. M. Pilling, S. Jennings, and N. K. Dulvy, “Current and future sustainability of island coral reef fisheries,” Current Biology, vol. 17, no. 7, pp. 655–658, 2007.
[7]  S. A. Sandin, J. E. Smith, and J. E. Smith, “Baselines and degradation of coral reefs in the Northern Line Islands,” PLoS ONE, vol. 3, no. 2, article no. e1548, 2008.
[8]  B. E. Lapointe, “Nutrient thresholds for bottom-up control of macroalgal blooms on coral reefs in Jamaica and southeast Florida,” Limnology and Oceanography, vol. 42, no. 5, pp. 1119–1131, 1998.
[9]  J. F. Bruno, L. E. Petes, C. D. Harvell, and A. Hettinger, “Nutrient enrichment can increase the severity of coral diseases,” Ecology Letters, vol. 6, no. 12, pp. 1056–1061, 2003.
[10]  P. W. Sammarco, “Echinoid grazing as a structuring force in coral communities: whole reef manipulations,” Journal of Experimental Marine Biology and Ecology, vol. 61, no. 1, pp. 31–55, 1982.
[11]  L. J. McCook, “Macroalgae, nutrients and phase shifts on coral reefs: scientific issues and management consequences for the Great Barrier Reef,” Coral Reefs, vol. 18, no. 4, pp. 357–367, 1999.
[12]  J. E. Smith, C. M. Smith, and C. L. Hunter, “An experimental analysis of the effects of herbivory and nutrient enrichment on benthic community dynamics on a Hawaiian reef,” Coral Reefs, vol. 19, no. 4, pp. 332–342, 2001.
[13]  B. E. Lapointe, P. J. Barile, C. S. Yentsch, M. M. Littler, D. S. Littler, and B. Kakuk, “The relative importance of nutrient enrichment and herbivory on macroalgal communities near Norman's Pond Cay, Exumas Cays, Bahamas: a "natural" enrichment experiment,” Journal of Experimental Marine Biology and Ecology, vol. 298, no. 2, pp. 275–301, 2004.
[14]  D. E. Burkepile and M. E. Hay, “Herbivore vs. nutrient control of marine primary producers: context-dependent effects,” Ecology, vol. 87, no. 12, pp. 3128–3139, 2006.
[15]  A.-S. Crépin, “Using fast and slow processes to manage resources with thresholds,” Environmental and Resource Economics, vol. 36, no. 2, pp. 191–213, 2007.
[16]  C. Stevenson, L. S. Katz, and L. S. Katz, “High apex predator biomass on remote Pacific islands,” Coral Reefs, vol. 26, no. 1, pp. 47–51, 2007.
[17]  N. K. Dulvy, N. V. C. Polunin, A. C. Mill, and N. A. J. Graham, “Size structural change in lightly exploited coral reef fish communities: evidence for weak indirect effects,” Canadian Journal of Fisheries and Aquatic Sciences, vol. 61, no. 3, pp. 466–475, 2004.
[18]  P. J. Mumby, C. P. Dahlgren, and C. P. Dahlgren, “Fishing, trophic cascades, and the process of grazing on coral reefs,” Science, vol. 311, no. 5757, pp. 98–101, 2006.
[19]  T. R. McClanahan, M. Nugues, and S. Mwachireya, “Fish and sea urchin herbivory and competition in Kenyan coral reef lagoons: the role of reef management,” Journal of Experimental Marine Biology and Ecology, vol. 184, no. 2, pp. 237–254, 1994.
[20]  T. R. McClanahan, “Primary succession of coral-reef algae: differing patterns on fished versus unfished reefs,” Journal of Experimental Marine Biology and Ecology, vol. 218, no. 1, pp. 77–102, 1997.
[21]  J. E. Smith, C. L. Hunter, and C. M. Smith, “The effects of top-down versus bottom-up control on benthic coral reef community structure,” Oecologia, vol. 163, no. 2, pp. 497–507, 2010.
[22]  S. A. Sandin, S. M. Walsh, and J. B. C. Jackson, “Prey release, trophic cascades, and phase shifts in tropical nearshore marine ecosystems,” in Trophic Cascades: Predators, Prey, and the Changing Dynamics of Nature, J. Estes and J. Terborgh, Eds., pp. 71–90, Island Press, 2010.
[23]  S. Jennings, S. P. R. Greenstreet, and J. D. Reynolds, “Structural change in an exploited fish community: a consequence of differential fishing effects on species with contrasting life histories,” Journal of Animal Ecology, vol. 68, no. 3, pp. 617–627, 1999.
[24]  D. Pauly, V. Christensen, J. Dalsgaard, R. Froese, and F. Torres Jr., “Fishing down marine food webs,” Science, vol. 279, no. 5352, pp. 860–863, 1998.
[25]  J. E. Cinner, T. R. McClanahan, T. M. Daw, N. A. J. Graham, J. Maina, S. K. Wilson, and T. P. Hughes, “Linking social and ecological systems to sustain coral reef fisheries,” Current Biology, vol. 19, no. 3, pp. 206–212, 2009.
[26]  D. S. Gruner, J. E. Smith, and J. E. Smith, “A cross-system synthesis of consumer and nutrient resource control on producer biomass,” Ecology Letters, vol. 11, no. 7, pp. 740–755, 2008.
[27]  M. D. Hunter and P. W. Price, “Playing chutes and ladders: heterogeneity and the relative roles of bottom-up and top-down forces in natural communities,” Ecology, vol. 73, no. 3, pp. 724–732, 1992.
[28]  G. Englund, “Importance of spatial scale and prey movements in predator caging experiments,” Ecology, vol. 78, no. 8, pp. 2316–2325, 1997.
[29]  N. L. Poff and K. Nelson-Baker, “Habitat heterogeneity and algal-grazer interactions in streams: explorations with a spatially explicit model,” Journal of the North American Benthological Society, vol. 16, no. 1, pp. 263–276, 1997.
[30]  Asian Development Bank, “Monetization in an atoll society:managing economic and social change,” Report 111002, Asian Development Bank, Manila, Philippines, 2002.
[31]  C. D. Woodroffe and R. F. McLean, “Pleistocene morphology and holocene emergence of Christmas (Kiritimati) Island, Pacific Ocean,” Coral Reefs, vol. 17, no. 3, pp. 235–248, 1998.
[32]  E. A. Dinsdale, O. Pantos, and O. Pantos, “Microbial ecology of four coral atolls in the Northern Line Islands,” PLoS ONE, vol. 3, no. 2, article no. e1584, 2008.
[33]  K. L. McLeod and H. M. Leslie, “Why ecosystem-based management?” in Ecosystem-Based Management for the Oceans, K. McLeod and H. Leslie, Eds., pp. 3–12, Island Press, Washington, DC, USA, 2009.
[34]  E. A. Laws and D. Redalje, “Effects of sewage enrichment on the phytoplankton population of a subtropical estuary,” Pacific Science, vol. 33, pp. 129–144, 1979.
[35]  P. R. F. Bell, “Eutrophication and coral reefs—some examples in the Great Barrier Reef lagoon,” Water Research, vol. 26, no. 5, pp. 553–568, 1992.
[36]  R. F. C. Mantoura, S. W. Wright, S. W. Jeffrey, R. G. Barlow, and D. E. Cummings, “Filtration and storage of pigments from microalgae,” in Phytoplankton pigments in oceanography, S. W. Jeffrey, R. F. C. Mantoura, and S. W. Wright, Eds., pp. 283–306, UNESCO, Paris, France, 1997.
[37]  M. H. Graham and M. S. Edwards, “Statistical significance versus fit: estimating the importance of individual factors in ecological analysis of variance,” Oikos, vol. 93, no. 3, pp. 505–513, 2001.
[38]  S. Olejnik and J. Algina, “Generalized eta and omega squared statistics: measures of effect size for some common research designs,” Psychological Methods, vol. 8, no. 4, pp. 434–447, 2003.
[39]  K. P. Burnham and D. R. Anderson, Model Selection and Multimodel Inference: A Practical Information-Theoretic Approach, Springer, New York, NY, USA, 2nd edition, 2002.
[40]  T. R. McClanahan and S. H. Shafir, “Causes and consequences of sea urchin abundance and diversity in Kenyan coral reef lagoons,” Oecologia, vol. 83, no. 3, pp. 362–370, 1990.
[41]  T. R. McClanahan and N. A. Muthiga, “Changes in Kenyan coral reef community structure and function due to exploitation,” Hydrobiologia, vol. 166, no. 3, pp. 269–276, 1988.
[42]  T. R. McClanahan, “Recovery of a coral reef keystone predator, Balistapus undulatus, in East African marine parks,” Biological Conservation, vol. 94, no. 2, pp. 191–198, 2000.
[43]  N. K. Dulvy, R. P. Freckleton, and N. V. C. Polunin, “Coral reef cascades and the indirect effects of predator removal by exploitation,” Ecology Letters, vol. 7, no. 5, pp. 410–416, 2004.
[44]  G. R. Russ and L. J. McCook, “Potential effects of a cyclone on benthic algal production and yield to grazers on coral reefs across the central Great Barrier Reef,” Journal of Experimental Marine Biology and Ecology, vol. 235, no. 2, pp. 237–254, 1999.
[45]  M. M. Littler, P. R. Taylor, and D. S. Littler, “Algal resistance to herbivory on a Caribbean barrier reef,” Coral Reefs, vol. 2, no. 2, pp. 111–118, 1983.
[46]  L. D. Coen and C. E. Tanner, “Morphological variation and differential susceptibility to herbivory in the tropical brown alga Lobophora variegata,” Marine Ecology Progress Series, vol. 54, pp. 287–298, 1989.
[47]  J. J. Leichter, H. L. Stewart, and S. L. Miller, “Episodic nutrient transport to Florida coral reefs,” Limnology and Oceanography, vol. 48, no. 4, pp. 1394–1407, 2003.
[48]  S. V. Smith, W. J. Kimmerer, E. A. Laws, R. E. Brock, and T. W. Walsh, “Kaneohe Bay sewage diversion experiment: perspectives on ecosystem responses to nutritional perturbation,” Pacific Science, vol. 35, no. 4, pp. 279–395, 1981.
[49]  NOAA, “Station 51028—Christmas Island,” National Data Buoy Center, 2010,
[50]  F. Guichard and G. Peterson, “Ecological cross-scale interactions,” in Ecosystem-based management for the oceans, K. McLeod and H. Leslie, Eds., pp. 74–91, Island Press, Washington, DC, USA, 2009.


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