The importance of structural complexity in coral reef ecosystems
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The importance of structural complexity in coral reefs has come to the fore with the global degradation of reef condition; however, the limited scale and replication of many studies have restricted our understanding of the role of complexity in the ecosystem. We qualitatively and quantitatively (where sufficient standardised data were available) assess the literature regarding the role of structural complexity in coral reef ecosystems. A rapidly increasing number of publications have studied the role of complexity in reef ecosystems over the past four decades, with a concomitant increase in the diversity of methods used to quantify structure. Quantitative analyses of existing data indicate a strong negative relationship between structural complexity and algal cover, which may reflect the important role complexity plays in enhancing herbivory by reef fishes. The cover of total live coral and branching coral was positively correlated with structural complexity. These habitat attributes may be creating much of the structure, resulting in a collinear relationship; however, there is also evidence of enhanced coral recovery from disturbances where structural complexity is high. Urchin densities were negatively correlated with structural complexity; a relationship that may be driven by urchins eroding reef structure or by their gregarious behaviour when in open space. There was a strong positive relationship between structural complexity and fish density and biomass, likely mediated through density-dependent competition and refuge from predation. More variable responses were found when assessing individual fish families, with all families examined displaying a positive relationship to structural complexity, but only half of these relationships were significant. Although only corroborated with qualitative data, structural complexity also seems to have a positive effect on two ecosystem services: tourism and shoreline protection. Clearly, structural complexity is an integral component of coral reef ecosystems, and it should be incorporated into monitoring programs and management objectives.
KeywordsCoral reef ecology Coral reef fishes Ecosystem function Diversity Marine protected areas Ecological methods
This study was funded through research fellowships from the Australian Research Council and Queensland Smart Futures Fund. An earlier draft of the manuscript was improved through the comments of Andrew Hoey.
- Bruno JF, Bertness MD (2001) Habitat modification and facilitation in benthic marine communities. In: Bertness MD, Gaines SD, Hay ME (eds) Marine community ecology. Sinauer, Sunderland, MA, pp 201–218Google Scholar
- Graham NAJ, McClanahan TR, MacNeil MA, Wilson SK, Polunin NVC, Jennings S, Chabanet P, Clark S, Spalding MD, Letourneur Y, Bigot L, Galzin R, Öhman MC, Garpe KC, Edwards AJ, Sheppard CRC (2008) Climate warming, marine protected areas and the ocean-scale integrity of coral reef ecosystems. PLoS ONE 3:e3039PubMedCrossRefGoogle Scholar
- Levitan DR (1988) Density-dependent size regulation and negative growth in the sea urchin Diadema antillarum Philippi. Oecologia 76:627–629Google Scholar
- McClanahan TR, Shafir SH (1990) Causes and consequences of sea urchin abundance and diversity in Kenyan coral reef lagoons. Oecologia 83:362–370Google Scholar
- Randall JE, Schroeder RE, Starck WA II (1964) Notes on the biology of the echinoid Diadema antillarum. Caribb J Sci 4:421–433Google Scholar
- Scoffin TP, Stearn CW, Boucher D, Frydl P, Hawkins CM, Hunter IG, MacGeachy JK (1980) Calcium carbonate budget of a fringing reef on the west coast of Barbados: Part II, Erosion, sediments and internal structure. Bull Mar Sci 30:475–508Google Scholar
- Spies TA (1998) Forest structure: a key to the ecosystem. Northwest Sci 72:34–39Google Scholar
- Stella JS, Pratchett MS, Hutchings PA, Jones GP (2011) Coral-associated invertebrates: diversity, ecological importance and vulnerability to disturbance. Oceanogr Mar Biol Annu Rev 49:43–104Google Scholar
- Wood LJ (2007) MPA Global: A database of the world’s Marine Protected Areas. UNEP- 694 WCMC & WWF, www.mpaglobal.org