Differential competitive abilities between Caribbean coral species and a brown alga: a year of experiments and a long-term perspective

Nugues, Maggy M.; Bak, Rolf P. M.

doi:10.3354/meps315075

Cited by 119 publications

(103 citation statements)

References 56 publications

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“…Coral-algal interactions need to be viewed in the context of the prevalent grazing intensity and nutrient regime in an area (Nugues and Bak 2006). Monitoring has shown that between 2003 and 2007, mean biomass of scarid parrotfish on Bonaire's reefs steadily declined from 7000 to 4000 g 100 m −2 (Alvarado et al 2007), and a 2006 nutrient survey suggests that Bonaire's reefs are at or beyond the threshold of nutrient pollution (Wieggers 2007).…”

Section: Discussionmentioning

confidence: 99%

Coral Community Decline at Bonaire, Southern Caribbean

Sommer¹,

Harrison²,

Brooks³

et al. 2011

bms

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We assessed the status of coral reef benthic communities at Bonaire, Netherlands Antilles, in December 2008 and January 2009 through ~5 km of photo transects taken at depths of 5, 10, and 20 m at 14 locations around the island. Univariate and multivariate analyses detected significant variation in benthic communities among depths and locations, as well as between leeward and windward sides of the island. Mean percentage cover of scleractinian corals ranged between 0.2% and 43.6% at the study sites and tended to be lowest at 5-m depth. The survey recorded 40 scleractinian coral species from 19 genera, within 10 families. Faviidae were by far the most abundant scleractinian family at all depths (predominantly Montastraea spp.), followed by Agariciidae at 20 and 10 m, and by Astrocoeniidae at 5-m depth. Macroalgal cover exceeded scleractinian coral cover at nearly all sites, averaging 34.9% (all samples pooled), compared with a pooled mean coral cover of 15.4%. Windward reefs were characterized by prolific growth of the brown algae Sargassum spp., and leeward reefs by growth of turf algae, Dictyota spp., Trichogloeopsis pedicellata (Howe) I. A. Abbott & Doty, and Lobophora variegata (Lamouroux) Womersley ex Oliveira. Damage from recent hurricanes was evident from the presence of toppled and fragmented corals, the movement of sand, and exposure of cemented Acropora cervicornis (Lamarck, 1816) rubble on the shallow reef platform. The combination of algal dominance and low to moderate coral cover are symptomatic of partly degraded reef systems, particularly as they coincide with elevated nutrients and reduced herbivory.

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Section: Discussionmentioning

confidence: 99%

Coral Community Decline at Bonaire, Southern Caribbean

Sommer¹,

Harrison²,

Brooks³

et al. 2011

bms

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“…In these field experiments, we used the corals P. porites (Caribbean Panama) and P. cylindrica (Fiji) because this is a pan-tropical genus common to both sites and used in other investigations of coral-seaweed competition (8,(17)(18)(19)22). The seaweeds we used were (i) common-to-abundant on these Poritid-dominated reefs, (ii) observed in contact with corals, and (iii) representative of a range of taxonomic and morphological forms.…”

Section: Methodsmentioning

confidence: 99%

“…Although smothering, shading, and abrasion by a limited number of seaweeds have been shown to negatively (13,(17)(18)(19) or positively (20) affect corals, chemically-mediated competition between adult corals and seaweeds has received limited attention. Numerous marine benthic organisms produce secondary metabolites that function to deter consumers or suppress competitors (21).…”

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confidence: 99%

Chemically rich seaweeds poison corals when not controlled by herbivores

Rasher

Hay

2010

Proc. Natl. Acad. Sci. U.S.A.

287

316

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Coral reefs are in dramatic global decline, with seaweeds commonly replacing corals. It is unclear, however, whether seaweeds harm corals directly or colonize opportunistically following their decline and then suppress coral recruitment. In the Caribbean and tropical Pacific, we show that, when protected from herbivores, ∼40 to 70% of common seaweeds cause bleaching and death of coral tissue when in direct contact. For seaweeds that harmed coral tissues, their lipid-soluble extracts also produced rapid bleaching. Coral bleaching and mortality was limited to areas of direct contact with seaweeds or their extracts. These patterns suggest that allelopathic seaweed-coral interactions can be important on reefs lacking herbivore control of seaweeds, and that these interactions involve lipid-soluble metabolites transferred via direct contact. Seaweeds were rapidly consumed when placed on a Pacific reef protected from fishing but were left intact or consumed at slower rates on an adjacent fished reef, indicating that herbivory will suppress seaweeds and lower frequency of allelopathic damage to corals if reefs retain intact food webs. With continued removal of herbivores from coral reefs, seaweeds are becoming more common. This occurrence will lead to increasing frequency of seaweed-coral contacts, increasing allelopathic suppression of remaining corals, and continuing decline of reef corals.A s foundation species, corals promote marine biodiversity, support a multitude of ecosystem functions, and provide goods and services critical to human societies (1, 2). However, coral reefs are in global decline, with reefs commonly converting from species-rich and topographically complex communities dominated by corals to species-poor and topographically simplified communities dominated by seaweeds (3-7). In the Caribbean, average cover of hard corals has declined by ∼80% in the last 3 decades (5) and more than 30% of the world's coral species face elevated risk of extinction (6). Monitoring (7), field experiments (8-10), and a meta-analysis (11) all indicate that herbivory is critical in preventing seaweed replacement of corals. However, the extent to which seaweeds drive these shifts by outcompeting adult corals in the absence of herbivory, or proliferate only after coral mortality is triggered by other causes (such as disease or bleaching) is debated (12-15). To compound this uncertainty, studies addressing seaweed-coral competition have: (i) produced variable results, (ii) rarely been conducted using numerous species-pairings, (iii) varied in experimental techniques (complicating comparisons), and (iv) sometimes been conducted in laboratory settings lacking ecologically realistic conditions (e.g., flow and turbulence). Thus, the general importance of competition between established seaweeds and corals remains uncertain. An understanding of mechanisms determining the outcomes of seaweed-coral interactions, and of how herbivory mediates these interactions, is needed if reefs are to be better managed, especially with the continu...

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“…Coral planulae cannot settle on macroalgae, and therefore the space occupied by macroalgae reduces the availability of suitable settlement space for corals (15). Algae can trap sediment that smothers coral recruits (16) and direct contact with macroalgae reduces coral growth rates (17) and may even result in direct overgrowth and coral mortality (18). It is also feasible that macroalgae can negatively influence corals through allelochemicals (19), triggering disease (20) and enhancing microbial activity driven by algal-derived dissolved organic carbon (21).…”

mentioning

confidence: 99%

Trophic cascade facilitates coral recruitment in a marine reserve

Mumby

Harborne

Williams

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

330

260

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Reduced fishing pressure and weak predator-prey interactions within marine reserves can create trophic cascades that increase the number of grazing fishes and reduce the coverage of macroalgae on coral reefs. Here, we show that the impacts of reserves extend beyond trophic cascades and enhance the process of coral recruitment. Increased fish grazing, primarily driven by reduced fishing, was strongly negatively correlated with macroalgal cover and resulted in a 2-fold increase in the density of coral recruits within a Bahamian reef system. Our conclusions are robust because four alternative hypotheses that may generate a spurious correlation between grazing and coral recruitment were tested and rejected. Grazing appears to influence the density and community structure of coral recruits, but no detectable influence was found on the overall size-frequency distribution, community structure, or cover of corals. We interpret this absence of pattern in the adult coral community as symptomatic of the impact of a recent disturbance event that masks the recovery trajectories of individual reefs. Marine reserves are not a panacea for conservation but can facilitate the recovery of corals from disturbance and may help sustain the biodiversity of organisms that depend on a complex three-dimensional coral habitat.biodiversity ͉ coral reef ͉ grazing ͉ predation M arine reserves have become one of the most widely adopted tools for managing commercially important fishes and protecting marine biodiversity (1). Several direct effects of reserves are relatively straightforward to anticipate: Reduced fishing mortality usually increases the biomass of target and bycatch species of fishes (2, 3), and reserve status may help prevent acute anthropogenic disturbance such as destructive fishing practices that damage benthic communities (4). However, by enhancing the abundance of fishery species, reserves may also exert indirect impacts on other nonfishery species that naturally interact with fishery species through processes of predation and competition (5).Because the indirect effects of reserves on biodiversity arise from species interactions and trophic cascades (6), they are generally complex and may have surprising outcomes (7,8). We reported such complex outcomes in a study of The Bahamas' Exuma Cays Land and Sea Park (ECLSP), which, at 442 km 2 , is one of the largest and most successful marine reserves in the Caribbean. The ECLSP is a rare example in which sustained fisheries exclusion has resulted in a high biomass of predatory fishes (2 kg per 100 m 2 ). Our a priori hypothesis was that high levels of piscivorous fishes such as the Nassau grouper (Epinephelus striatus) would exert top-down predatory impacts on grazing fishes (a prey item) and, by reducing the biomass of grazers, promote increases in the cover of macroalgae. However, the hypothesis was not supported because large-bodied species of grazer (parrotfish) were found to experience a size-escape from predation, and therefore the expected negative effects of trophic casc...

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Differential competitive abilities between Caribbean coral species and a brown alga: a year of experiments and a long-term perspective

Cited by 119 publications

References 56 publications

Coral Community Decline at Bonaire, Southern Caribbean

Coral Community Decline at Bonaire, Southern Caribbean

Chemically rich seaweeds poison corals when not controlled by herbivores

Trophic cascade facilitates coral recruitment in a marine reserve

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