Carbon Cycling Hysteresis in Permeable Carbonate Sands over a Diel Cycle: Implications for Ocean Acidification

Authors

Tyler Cyronak, Southern Cross University - Lismore, AustraliaFollow
Isaac R. Santos, Southern Cross University - Lismore, Australia
Ashly McMahon, Southern Cross University - Lismore, Australia
Bradley D. Eyre, Southern Cross University - Lismore, Australia

ORCID

0000-0003-3556-7616

Document Type

Article

Publication Title

Limnology and Oceanography

ISSN

0024-3590

Publication Date

1-213

Abstract

Dissolved inorganic carbon, dissolved oxygen, H⁺, and alkalinity fluxes from permeable carbonate sediments at Heron Island (Great Barrier Reef) were measured over one diel cycle using benthic chambers designed to induce advective pore‐water exchange. A complex hysteretic pattern between carbonate precipitation and dissolution in sands and the aragonite saturation state (Ω_Ar) of the overlying chamber water was observed throughout the incubations. During the day, precipitation followed a hysteretic pattern based on the incidence of photosynthetically active radiation with lower precipitation rates in the morning than in the afternoon. The observed diel hysteresis seems to reflect a complex interaction between photosynthesis and respiration rather than ΩAr of the overlying water as the main driver of carbonate precipitation and dissolution within these permeable sediments. Changes in flux rates over a diel cycle demonstrate the importance of taking into account the short‐term variability of benthic metabolism when calculating net daily flux rates. Based on one diel cycle, the sediments were a net daily source of alkalinity to the water column (5.13 to 8.84 mmol m⁻² d⁻¹, depending on advection rates), and advection had a net stimulatory effect on carbonate dissolution. The enhanced alkalinity release associated with benthic metabolism and pore‐water advection may partially buffer shallow coral reef ecosystems against ocean acidification on a local scale.

DOI

10.4319/lo.2013.58.1.0131

Volume

58

Issue

1

First Page

131

Last Page

143

Comments

©2013, by the Association for the Sciences of Limnology and Oceanography, Inc.

Additional Comments

Australian Research Council Discovery grant #: DP110103638

NSUWorks Citation

Tyler Cyronak, Isaac R. Santos, Ashly McMahon, and Bradley D. Eyre. 213. Carbon Cycling Hysteresis in Permeable Carbonate Sands over a Diel Cycle: Implications for Ocean Acidification .Limnology and Oceanography , (1) : 131 -143. https://nsuworks.nova.edu/occ_facarticles/1052.