Organic matter release by the dominant primary producers in a Caribbean reef lagoon: implication for in situ O2 availability

Haas, Andreas F.; Jantzen, Carin; Naumann, Malik S.; Iglesias-Prieto, Roberto; Wild, Christian

doi:10.3354/meps08631

Cited by 76 publications

(92 citation statements)

References 80 publications

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“…Here the proposed mechanism is the stimulation of heterotrophic microbes by the dissolved organic carbon released by the benthic algae, which in turn leads to asphyxiation of the coral (Smith et al, 2006). Turf algae on coral reefs can exude dissolved organic carbon at rates of 12.2 ± 2.1 mg C m À2 h À1 (Haas et al, 2010b), whereas corals are net consumers of dissolved organic carbon (Haas et al, 2010a). This suggests that the composition of the benthic community can influence the availability of organic matter, thereby providing a possible mechanism for the observed shifts in the microbial community associated with the black reef.…”

Section: The Effects Of Iron Enrichment On Coral Healthmentioning

confidence: 99%

Black reefs: iron-induced phase shifts on coral reefs

et al. 2011

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The Line Islands are calcium carbonate coral reef platforms located in iron-poor regions of the central Pacific. Natural terrestrial run-off of iron is non-existent and aerial deposition is extremely low. However, a number of ship groundings have occurred on these atolls. The reefs surrounding the shipwreck debris are characterized by high benthic cover of turf algae, macroalgae, cyanobacterial mats and corallimorphs, as well as particulate-laden, cloudy water. These sites also have very low coral and crustose coralline algal cover and are call black reefs because of the dark-colored benthic community and reduced clarity of the overlying water column. Here we use a combination of benthic surveys, chemistry, metagenomics and microcosms to investigate if and how shipwrecks initiate and maintain black reefs. Comparative surveys show that the live coral cover was reduced from 40 to 60% to o10% on black reefs on Millennium, Tabuaeran and Kingman. These three sites are relatively large (40.75 km 2 ). The phase shift occurs rapidly; the Kingman black reef formed within 3 years of the ship grounding. Iron concentrations in algae tissue from the Millennium black reef site were six times higher than in algae collected from reference sites. Metagenomic sequencing of the Millennium Atoll black reef-associated microbial community was enriched in iron-associated virulence genes and known pathogens. Microcosm experiments showed that corals were killed by black reef rubble through microbial activity. Together these results demonstrate that shipwrecks and their associated iron pose significant threats to coral reefs in iron-limited regions.

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Section: The Effects Of Iron Enrichment On Coral Healthmentioning

confidence: 99%

Black reefs: iron-induced phase shifts on coral reefs

et al. 2011

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“…Type III and IV secretion pathways, hallmarks of pathogenesis but important for some symbiotic interactions [59,60], were also lower at these three interface types, potentially indicating a breakdown of symbiosis. Carbohydrate metabolisms were enriched along these same three interfaces ( figure 4 and table 1) and bacterial communities at all coral-algal interfaces showed changes similar to DOC stressed corals (electronic supplementary material, figure S4), together suggesting that bacteria present at some coral-algal interfaces may be consuming carbohydrates released from the neighbouring algae [51]. Despite the earlier-mentioned similarities, the different types of algae examined here have characteristic impacts on the bacterial component of the neighbouring coral holobiont.…”

Section: Discussion (A)mentioning

confidence: 87%

“…allelochemicals) from some algae have been shown to damage corals, these compounds are highly specific to the algal species and require direct contact for effect [36]. In contrast, DOC is a watersoluble product of photosynthesis that is potentially released by many algae [51,63] and does not require contact to affect the coral holobiont. Various forms of DOC released by algae have been shown to kill corals and increase microbial growth rates [40,41], while some algae cause coral death and hypoxia that is mediated by microbes [38].…”

Section: Discussion (A)mentioning

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.

117

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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“…There is good evidence that primary producers on coral reefs (seaweeds and corals) release up to 50% of their fixed carbon as mucus and other exudates, and that most of these exudates become part of the DOC pool (Wild et al 2004, Haas et al 2010. Further, sponges have the capacity to turn over huge quantities of seawater in the process of feeding.…”

Section: Open Pen Access Ccessmentioning

confidence: 99%