Coral Ba/Ca records of sediment input to the fringing reef of the southshore of Moloka’i, Hawai’i over the last several decades

Prouty, Nancy G.; Field, Michael E.; Stock, J. D.; Jupiter, Stacy D.; McCulloch, Malcolm T.

doi:10.1016/j.marpolbul.2010.05.024

Cited by 70 publications

(36 citation statements)

References 65 publications

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“…However, sedimentation on reefs is also increasing (Fabricius 2005), particularly on fringing reefs exposed to the stresses of watershed development via agricultural land use (De'ath and Fabricius 2010). On some reefs, these changes have become so widespread that many believe the baseline has shifted toward a new ambient condition of heightened sedimentation (McCulloch et al 2003;Richmond et al 2007;Prouty et al 2010) and reduced herbivory (Hughes et al 2010). There is substantial correlative evidence that macroalgae ([1 cm) are more abundant under higher sediment loads (McCook 1996(McCook , 1999De'ath and Fabricius 2010), yet it is not known how increased sediment loads interact with nutrients and herbivory to influence algal dynamics.…”

Section: Introductionmentioning

confidence: 99%

Sediments influence accumulation of two macroalgal species through novel but differing interactions with nutrients and herbivory

et al. 2016

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Despite increasing concern that sediment loads from disturbed watersheds facilitate algal dominance on tropical reefs, little is known of how sediments interact with two primary drivers of algal communities, nutrients and herbivory. We examined the effects of sediment loads on the thalli of two increasingly abundant genera of macroalgae, Galaxaura and Padina, in a bay subject to terrestrial sediment influx in Mo'orea, French Polynesia. Field experiments examining (1) overall effects of ambient sediments and (2) interacting effects of sediments (ambient/removal) and herbivores (caged/uncaged) demonstrated that sediments had strong but opposite effects on both species' biomass accumulation. Sediment removal increased accumulation of Padina boryana Thivy 50% in the initial field experiment but had no effect in the second; rather, in a novel interaction, herbivores overcompensated for increases in tissue nutrient stores that occurred with sediments loads, likely by preferential consumption of nutrient-rich meristematic tissues. Despite negative effects of sediments on biomass, Padina maintained rapid growth across treatments in both experiments. In contrast, positive growth in Galaxaura divaricata Kjellman only occurred with ambient sediment loads. In mesocosm experiments testing interactions of added nutrients and sediments on growth, Galaxaura grew at equivalent rates with sediments (collected from thalli on the reef) as with additions of nitrate and phosphate, suggesting sediments provide a nutrient subsidy. For Padina, however, the only effect was a 50% reduction in growth with sediment. Overall, retention of thallus sediments creates a positive feedback that Galaxaura appears to require to sustain net growth, while Padina merely tolerates sediments. These results indicate that sediments can modify nutrient and herbivore control of algae in ways that differ among species, with the potential for strong and unexpected effects on the abundance and composition of tropical reef macroalgae.

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Section: Introductionmentioning

confidence: 99%

Sediments influence accumulation of two macroalgal species through novel but differing interactions with nutrients and herbivory

et al. 2016

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“…, attributed to sediment input in Hawaii (Prouty et al, 2010) (see Table 1). The partition coefficient temperature dependence is not sufficient to explain such large coral Ba/Ca peaks.…”

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confidence: 99%

Relationship between water and aragonite barium concentrations in aquaria reared juvenile corals

Gonneea

Cohen

DeCarlo

et al. 2017

Geochimica et Cosmochimica Acta

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Coral barium to calcium (Ba/Ca) ratios have been used to reconstruct records of upwelling, river and groundwater discharge, and sediment and dust input to the coastal ocean. However, this proxy has not yet been explicitly tested to determine if Ba inclusion in the coral skeleton is directly proportional to seawater Ba concentration and to further determine how additional factors such as temperature and calcification rate control coral Ba/Ca ratios. We measured the inclusion of Ba within aquaria reared juvenile corals (Favia fragum) at three temperatures ($27.7, 24.6 and 22.5°C) and three seawater Ba concentrations (73, 230 and 450 nmol kg À1). Coral polyps were settled on tiles conditioned with encrusting coralline algae, which complicated chemical analysis of the coral skeletal material grown during the aquaria experiments. We utilized Sr/Ca ratios of encrusting coralline algae (as low as 3.4 mmol mol À1) to correct coral Ba/Ca for this contamination, which was determined to be 26 ± 11% using a two end member mixing model. Notably, there was a large range in Ba/Ca across all treatments, however, we found that Ba inclusion was linear across the full concentration range. The temperature sensitivity of the distribution coefficient is within the range of previously reported values. Finally, calcification rate, which displayed large variability, was not correlated to the distribution coefficient. The observed temperature dependence predicts a change in coral Ba/Ca ratios of 1.1 lmol mol À1 from 20 to 28°C for typical coastal ocean Ba concentrations of 50 nmol kg À1 . Given the linear uptake of Ba by corals observed in this study, coral proxy records that demonstrate peaks of 10-25 lmol mol À1 would require coastal seawater Ba of between 60 and 145 nmol kg À1 . Further validation of the coral Ba/Ca proxy requires evaluation of changes in seawater chemistry associated with the environmental perturbation recorded by the coral as well as verification of these results for Porites species, which are widely used in paleo reconstructions. Published by Elsevier Ltd.

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“…Indeed, measurement of coral Ba/Ca has expanded coral climate proxies beyond sea surface temperature to include proxy records of river discharge (Alibert et al, 2003;Carriquiry and Horta-Puga, 2010;Fleitmann et al, 2007;Jupiter et al, 2008;Sinclair and McCulloch, 2004), river sediment transport Prouty et al, 2010), upwelling (Alibert and Kinsley, 2008; Lea et al, 1989;Montaggioni et al, 2006;Tudhope et al, 1996) and groundwater discharge (itself a precipitation proxy, Horta-Puga and Carriquiry, 2012). However, several studies report coral Ba/Ca ratios that did not vary in concert with a known driver.…”

mentioning

confidence: 99%

Temporal variability in chemical cycling of the subterranean estuary and associated chemical loading to the coastal ocean

Gonneea¹

2014

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Coral Ba/Ca records of sediment input to the fringing reef of the southshore of Moloka’i, Hawai’i over the last several decades

Cited by 70 publications

References 65 publications

Sediments influence accumulation of two macroalgal species through novel but differing interactions with nutrients and herbivory

Sediments influence accumulation of two macroalgal species through novel but differing interactions with nutrients and herbivory

Relationship between water and aragonite barium concentrations in aquaria reared juvenile corals

Temporal variability in chemical cycling of the subterranean estuary and associated chemical loading to the coastal ocean

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