Reduction of zooxanthellae density, chlorophyll a concentration, and tissue thickness of the coral <i>Montastraea faveolata</i>
 (Scleractinia) when competing with mixed turf algae

Quan-Young, Lizette I.; Espinoza-Ávalos, Julio

doi:10.4319/lo.2006.51.2.1159

Cited by 43 publications

(45 citation statements)

References 28 publications

(51 reference statements)

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“…An earlier study from Mexico on a sibling species of Montastraea annularis , ( M. faveolata ) also showed that turf algae had negative effects on neighbouring corals [27] by causing a decrease in the coral's zooxanthellae density, Chlorophyll a concentration, and tissue thickness. Healthy M. faveolata transplants were always overgrown by the turf algae, and in some cases killed [27].…”

Section: Discussionmentioning

confidence: 95%

The Effects of Nutrient Enrichment and Herbivore Abundance on the Ability of Turf Algae to Overgrow Coral in the Caribbean

et al. 2010

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Turf algae are multispecies communities of small marine macrophytes that are becoming a dominant component of coral reef communities around the world. To assess the impact of turf algae on corals, we investigated the effects of increased nutrients (eutrophication) on the interaction between the Caribbean coral Montastraea annularis and turf algae at their growth boundary. We also assessed whether herbivores are capable of reducing the abundance of turf algae at coral-algae boundaries. We found that turf algae cause visible (overgrowth) and invisible negative effects (reduced fitness) on neighbouring corals. Corals can overgrow neighbouring turf algae very slowly (at a rate of 0.12 mm 3 wk−1) at ambient nutrient concentrations, but turf algae overgrew corals (at a rate of 0.34 mm 3 wk−1) when nutrients were experimentally increased. Exclusion of herbivores had no measurable effect on the rate turf algae overgrew corals. We also used PAM fluorometry (a common approach for measuring of a colony's “fitness”) to detect the effects of turf algae on the photophysiology of neighboring corals. Turf algae always reduced the effective photochemical efficiency of neighbouring corals, regardless of nutrient and/or herbivore conditions. The findings that herbivores are not capable of controlling the abundance of turf algae and that nutrient enrichment gives turf algae an overall competitive advantage over corals together have serious implications for the health of Caribbean coral reef systems. At ambient nutrient levels, traditional conservation measures aimed at reversing coral-to-algae phase shifts by reducing algal abundance (i.e., increasing herbivore populations by establishing Marine Protected Areas or tightening fishing regulations) will not necessarily reduce the negative impact of turf algae on local coral communities. Because turf algae have become the most abundant benthic group on Curaçao (and likely elsewhere in the Caribbean), new conservation strategies are required to mitigate their negative impact on coral communities.

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Section: Discussionmentioning

confidence: 95%

The Effects of Nutrient Enrichment and Herbivore Abundance on the Ability of Turf Algae to Overgrow Coral in the Caribbean

et al. 2010

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“…The two species of macroalgae examined here also caused DO levels to decrease below ambient, but the magnitudes of their effects differed. Turf algae and many macroalgae have been shown to limit coral growth and negatively impact the bordering coral tissue [17,18,23,24,26], lower coral fecundity [27] and inhibit larval settlement [45][46][47], thereby impacting corals on multiple scales in time and space (table 1). Given the greater abundance of coral interactions with turf algae relative to other functional groups of algae around the world (figure 5; [17,18]), coral-turf interactions are likely important in influencing the structure of benthic coral reef communities.…”

Section: Discussion (A)mentioning

confidence: 99%

“…While this phenomenon has been well documented, the mechanisms by which algae overtake corals are not well understood. Competition between corals and benthic algae is common on coral reefs worldwide [17][18][19][20], and these interactions are frequently harmful to the coral, causing tissue damage and necrosis [3,[20][21][22][23], reduced zooxanthellar function [23][24][25][26] and reduced coral fecundity [3,20,27]. On the other hand, some algae have little effect on corals [28,29], such as certain species of CCA that promote coral settlement [30,31] and inhibit recruitment of macroalgae that would otherwise compete with corals [32,33].…”

Section: Introductionmentioning

confidence: 99%

Microbial to reef scale interactions between the reef-building coral Montastraea annularis and benthic algae

Barott

Rodriguez-Mueller

Youle³

et al. 2011

Proc. R. Soc. B.

114

112

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Competition between reef-building corals and benthic algae is of key importance for reef dynamics. These interactions occur on many spatial scales, ranging from chemical to regional. Using microprobes, 16S rDNA pyrosequencing and underwater surveys, we examined the interactions between the reef-building coral Montastraea annularis and four types of benthic algae. The macroalgae Dictyota bartayresiana and Halimeda opuntia, as well as a mixed consortium of turf algae, caused hypoxia on the adjacent coral tissue. Turf algae were also associated with major shifts in the bacterial communities at the interaction zones, including more pathogens and virulence genes. In contrast to turf algae, interactions with crustose coralline algae (CCA) and M. annularis did not appear to be antagonistic at any scale. These zones were not hypoxic, the microbes were not pathogen-like and the abundance of coral-CCA interactions was positively correlated with per cent coral cover. We propose a model in which fleshy algae (i.e. some species of turf and fleshy macroalgae) alter benthic competition dynamics by stimulating bacterial respiration and promoting invasion of virulent bacteria on corals. This gives fleshy algae a competitive advantage over corals when human activities, such as overfishing and eutrophication, remove controls on algal abundance. Together, these results demonstrate the intricate connections and mechanisms that structure coral reefs.

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“…However, there is no clear mechanistic link between algae and coral diseases. Contact between corals and algae commonly cause a suite of stresses for corals, such as localized tissue death, reductions in tissue thickness and zooxanthellae density and lower photosynthetic efficiency often resulting in bleaching [21], [22], all of which could increase coral susceptibility to disease pathogens. Current evidence suggests that algae have the ability to directly harm corals in three principal ways; 1) shading, 2) abrasion resulting in a physical injury, and 3) the release of poisonous allelochemicals (reviewed by [23]).…”

Section: Introductionmentioning

confidence: 99%

Algae as Reservoirs for Coral Pathogens

2013

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Benthic algae are associated with coral death in the form of stress and disease. It's been proposed that they release exudates, which facilitate invasion of potentially pathogenic microbes at the coral-algal interface, resulting in coral disease. However, the original source of these pathogens remains unknown. This study examined the ability of benthic algae to act as reservoirs of coral pathogens by characterizing surface associated microbes associated with major Caribbean and Indo-Pacific algal species/types and by comparing them to potential pathogens of two dominant coral diseases: White Syndrome (WS) in the Indo-Pacific and Yellow Band Disease (YBD) in the Caribbean. Coral and algal sampling was conducted simultaneously at the same sites to avoid spatial effects. Potential pathogens were defined as those absent or rare in healthy corals, increasing in abundance in healthy tissues adjacent to a disease lesion, and dominant in disease lesions. Potentially pathogenic bacteria were detected in both WS and YBD and were also present within the majority of algal species/types (54 and 100% for WS and YBD respectively). Pathogenic ciliates were associated only with WS and not YBD lesions and these were also present in 36% of the Indo-Pacific algal species. Although potential pathogens were associated with many algal species, their presence was inconsistent among replicate algal samples and detection rates were relatively low, suggestive of low density and occurrence. At the community level, coral-associated microbes irrespective of the health of their host differed from algal-associated microbes, supporting that algae and corals have distinctive microbial communities associated with their tissue. We conclude that benthic algae are common reservoirs for a variety of different potential coral pathogens. However, algal-associated microbes alone are unlikely to cause coral death. Initial damage or stress to the coral via other competitive mechanisms is most likely a prerequisite to potential transmission of these pathogens.

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Reduction of zooxanthellae density, chlorophyll a concentration, and tissue thickness of the coral Montastraea faveolata (Scleractinia) when competing with mixed turf algae

Cited by 43 publications

References 28 publications

The Effects of Nutrient Enrichment and Herbivore Abundance on the Ability of Turf Algae to Overgrow Coral in the Caribbean

The Effects of Nutrient Enrichment and Herbivore Abundance on the Ability of Turf Algae to Overgrow Coral in the Caribbean

Microbial to reef scale interactions between the reef-building coral Montastraea annularis and benthic algae

Algae as Reservoirs for Coral Pathogens

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