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Hysteresis between coral reef calcification and the seawater aragonite saturation state
Author(s) -
McMahon Ashly,
Santos Isaac R.,
Cyronak Tyler,
Eyre Bradley D.
Publication year - 2013
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/grl.50802
Subject(s) - aragonite , reef , coral reef , ocean acidification , coral , oceanography , saturation (graph theory) , seawater , environmental science , hysteresis , ecosystem , extrapolation , coral bleaching , resilience of coral reefs , geology , ecology , calcite , biology , mineralogy , physics , mathematics , combinatorics , mathematical analysis , quantum mechanics
Some predictions of how ocean acidification (OA) will affect coral reefs assume a linear functional relationship between the ambient seawater aragonite saturation state (Ω a ) and net ecosystem calcification (NEC). We quantified NEC in a healthy coral reef lagoon in the Great Barrier Reef during different times of the day. Our observations revealed a diel hysteresis pattern in the NEC versus Ω a relationship, with peak NEC rates occurring before the Ω a peak and relatively steady nighttime NEC in spite of variable Ω a . Net ecosystem production had stronger correlations with NEC than light, temperature, nutrients, pH, and Ω a . The observed hysteresis may represent an overlooked challenge for predicting the effects of OA on coral reefs. If widespread, the hysteresis could prevent the use of a linear extrapolation to determine critical Ω a threshold levels required to shift coral reefs from a net calcifying to a net dissolving state.