Dataset Information

Coral skeletons reveal the history of nitrogen cycling in the coastal Great Barrier Reef.

ABSTRACT: Anthropogenic nutrient discharge to coastal marine environments is commonly associated with excessive algal growth and ecosystem degradation. However in the world's largest coral reef ecosystem, the Great Barrier Reef (GBR), the response to enhanced terrestrial nutrient inputs since European settlement in the 1850's remains unclear. Here we use a 333 year old composite record (1680-2012) of 15N/14N in coral skeleton-bound organic matter to understand how nitrogen cycling in the coastal GBR has responded to increased anthropogenic nutrient inputs. Our major robust finding is that the coral record shows a long-term decline in skeletal 15N/14N towards the present. We argue that this decline is evidence for increased coastal nitrogen fixation rather than a direct reflection of anthropogenic nitrogen inputs. Reducing phosphorus discharge and availability would short-circuit the nitrogen fixation feedback loop and help avoid future acute and chronic eutrophication in the coastal GBR.

SUBMITTER: Erler DV

PROVIDER: S-EPMC7083840 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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Coral skeletons reveal the history of nitrogen cycling in the coastal Great Barrier Reef.

Erler Dirk V DV Farid Hanieh Tohidi HT Glaze Thomas D TD Carlson-Perret Natasha L NL Lough Janice M JM

Nature communications 20200320 1

Anthropogenic nutrient discharge to coastal marine environments is commonly associated with excessive algal growth and ecosystem degradation. However in the world's largest coral reef ecosystem, the Great Barrier Reef (GBR), the response to enhanced terrestrial nutrient inputs since European settlement in the 1850's remains unclear. Here we use a 333 year old composite record (1680-2012) of <sup>15</sup>N/<sup>14</sup>N in coral skeleton-bound organic matter to understand how nitrogen cycling in ...[more]

PMID: 32198372

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Project description:Much research on coral reefs has documented differential declines in coral and associated organisms. In order to contextualise this general degradation, research on community composition is necessary in the context of varied disturbance histories and the biological processes and physical features thought to retard or promote recovery. We conducted a spatial assessment of coral reef communities across five reefs of the central Great Barrier Reef, Australia, with known disturbance histories, and assessed patterns of coral cover and community composition related to a range of other variables thought to be important for reef dynamics. Two of the reefs had not been extensively disturbed for at least 15 years prior to the surveys. Three of the reefs had been severely impacted by crown-of-thorns starfish outbreaks and coral bleaching approximately a decade before the surveys, from which only one of them was showing signs of recovery based on independent surveys. We incorporated wave exposure (sheltered and exposed) and reef zone (slope, crest and flat) into our design, providing a comprehensive assessment of the spatial patterns in community composition on these reefs. Categorising corals into life history groupings, we document major coral community differences in the unrecovered reefs, compared to the composition and covers found on the undisturbed reefs. The recovered reef, despite having similar coral cover, had a different community composition from the undisturbed reefs, which may indicate slow successional processes, or a different natural community dominance pattern due to hydrology and other oceanographic factors. The variables that best correlated with patterns in the coral community among sites included the density of juvenile corals, herbivore fish biomass, fish species richness and the cover of macroalgae. Given increasing impacts to the Great Barrier Reef, efforts to mitigate local stressors will be imperative to encouraging coral communities to persist into the future.

Dataset Information

Coral skeletons reveal the history of nitrogen cycling in the coastal Great Barrier Reef.

Publications

Coral skeletons reveal the history of nitrogen cycling in the coastal Great Barrier Reef.

Similar Datasets

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