Tropical seagrass meadows modify seawater carbon chemistry: implications for coral reefs impacted by ocean acidification

Unsworth, Richard K. F.; Collier, Catherine; Henderson, Gideon M.; McKenzie, Len J.

doi:10.1088/1748-9326/7/2/024026

Cited by 182 publications

(163 citation statements)

References 54 publications

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“…The capability of seagrasses to elevate local mean pH has led to them being described as potential refugia under ocean acidification (Manzello et al, 2012), since they buffer resident species from rising seawater acidity (Hofmann et al, 2011;Manzello et al, 2012;Hendriks et al, 2014). Unsworth et al (2012) proposed that the photosynthetic activity of seagrass meadows in the IndoPacific could enhance seawater physicochemical conditions to increase coral calcification downstream by as much as 18%. However at night, high respiration rates can lead to seagrass meadows becoming a source of CO 2 (Schmalz and Swanson, 1969), causing large drops in local seawater pH, that at several locations have caused pH to fall below 7.8 (Camp et al, 2016a,b), creating conditions predicted under future ocean acidification (Feely et al, 2004).…”

Section: Highly Variable Ph/co 2 Environmentsmentioning

confidence: 99%

The Future of Coral Reefs Subject to Rapid Climate Change: Lessons from Natural Extreme Environments

et al. 2018

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Global climate change and localized anthropogenic stressors are driving rapid declines in coral reef health. In vitro experiments have been fundamental in providing insight into how reef organisms will potentially respond to future climates. However, such experiments are inevitably limited in their ability to reproduce the complex interactions that govern reef systems. Studies examining coral communities that already persist under naturally-occurring extreme and marginal physicochemical conditions have therefore become increasingly popular to advance ecosystem scale predictions of future reef form and function, although no single site provides a perfect analog to future reefs. Here we review the current state of knowledge that exists on the distribution of corals in marginal and extreme environments, and geographic sites at the latitudinal extremes of reef growth, as well as a variety of shallow reef systems and reef-neighboring environments (including upwelling and CO 2 vent sites). We also conduct a synthesis of the abiotic data that have been collected at these systems, to provide the first collective assessment on the range of extreme conditions under which corals currently persist. We use the review and data synthesis to increase our understanding of the biological and ecological mechanisms that facilitate survival and success under sub-optimal physicochemical conditions. This comprehensive assessment can begin to: (i) highlight the extent of extreme abiotic scenarios under which corals can persist, (ii) explore whether there are commonalities in coral taxa able to persist in such extremes, (iii) provide evidence for key mechanisms required to support survival and/or persistence under sub-optimal environmental conditions, and (iv) evaluate the potential of current sub-optimal coral environments to act as potential refugia under changing environmental conditions. Such a collective approach is critical to better understand the future survival of corals in our changing environment. We finally outline priority areas for future research on extreme and marginal coral environments, and discuss the additional management options they may provide for corals through refuge or by providing genetic stocks of stress tolerant corals to support proactive management strategies.

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Section: Highly Variable Ph/co 2 Environmentsmentioning

confidence: 99%

The Future of Coral Reefs Subject to Rapid Climate Change: Lessons from Natural Extreme Environments

et al. 2018

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“…Furthermore, shallow-water coastal environments may be subject to large annual and daily temperature and salinity fluctuations that in turn control the carbonate chemistry at a given site. Diurnal fluctuations .1 pH unit have been observed in seagrass meadows (Semesi et al 2009) and increases in pH of up to 0.38 units have been associated with the presence of seagrass meadows (Unsworth et al 2012). In Florida Bay where seagrass beds are common, extensive variation in pH (7.85-8.1) and pCO 2 (325-725 matm) were observed in samples taken every 2 months (Millero et al 2001).…”

Section: Introductionmentioning

confidence: 99%

Variability of the carbonate chemistry in a shallow, seagrass-dominated ecosystem: implications for ocean acidification experiments

Challener

Robbins

McClintock

2016

Mar. Freshwater Res.

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Abstract. Open ocean observations have shown that increasing levels of anthropogenically derived atmospheric CO 2 are causing acidification of the world's oceans. Yet little is known about coastal acidification and studies are just beginning to characterise the carbonate chemistry of shallow, nearshore zones where many ecologically and economically important organisms occur. We characterised the carbonate chemistry of seawater within an area dominated by seagrass beds (Saint Joseph Bay, Florida) to determine the extent of variation in pH and pCO 2 over monthly and daily timescales. Distinct diel and seasonal fluctuations were observed at daily and monthly timescales respectively, indicating the influence of photosynthetic and respiratory processes on the local carbonate chemistry. Over the course of a year, the range in monthly values of pH (7.36-8.28), aragonite saturation state (0.65-5.63), and calculated pCO 2 (195-2537 matm) were significant. When sampled on a daily basis the range in pH (7.70-8.06), aragonite saturation state (1.86-3.85), and calculated pCO 2 (379-1019 matm) also exhibited significant range and indicated variation between timescales. The results of this study have significant implications for the design of ocean acidification experiments where nearshore species are utilised and indicate that coastal species are experiencing far greater fluctuations in carbonate chemistry than previously thought.

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“…Because seagrasses are net photosynthesisers and are highly productive, they also rapidly utilise carbon from the water column. This has resulted in considerable attention being given to the role seagrass plays in altering seawater chemistry and potentially buffering small-scale impacts of ocean acidification on calcifying fauna such as corals and molluscs [9].…”

Section: Why Are Seagrass Meadows Important?mentioning

confidence: 99%

Seagrass meadows

Unsworth

Cullen-Unsworth

2017

Current Biology

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Tropical seagrass meadows modify seawater carbon chemistry: implications for coral reefs impacted by ocean acidification

Cited by 182 publications

References 54 publications

The Future of Coral Reefs Subject to Rapid Climate Change: Lessons from Natural Extreme Environments

The Future of Coral Reefs Subject to Rapid Climate Change: Lessons from Natural Extreme Environments

Variability of the carbonate chemistry in a shallow, seagrass-dominated ecosystem: implications for ocean acidification experiments

Seagrass meadows

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