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Tropical cyclones cause CaCO 3 undersaturation of coral reef seawater in a high‐CO 2 world
Author(s) -
Manzello Derek,
Enochs Ian,
Musielewicz Sylvia,
Carlton Renée,
Gledhill Dwight
Publication year - 2013
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/jgrc.20378
Subject(s) - ocean acidification , aragonite , seawater , oceanography , coral reef , reef , tropical cyclone , environmental science , coral , storm , carbonate , calcite , resilience of coral reefs , geology , chemistry , geochemistry , organic chemistry
Ocean acidification is the global decline in seawater pH and calcium carbonate (CaCO 3 ) saturation state (Ω) due to the uptake of anthropogenic CO 2 by the world's oceans. Acidification impairs CaCO 3 shell and skeleton construction by marine organisms. Coral reefs are particularly vulnerable, as they are constructed by the CaCO 3 skeletons of corals and other calcifiers. We understand relatively little about how coral reefs will respond to ocean acidification in combination with other disturbances, such as tropical cyclones. Seawater carbonate chemistry data collected from two reefs in the Florida Keys before, during, and after Tropical Storm Isaac provide the most thorough data to‐date on how tropical cyclones affect the seawater CO 2 system of coral reefs. Tropical Storm Isaac caused both an immediate and prolonged decline in seawater pH. Aragonite saturation state was depressed by 1.0 for a full week after the storm impact. Based on current “business‐as‐usual” CO 2 emissions scenarios, we show that tropical cyclones with high rainfall and runoff can cause periods of undersaturation (Ω < 1.0) for high‐Mg calcite and aragonite mineral phases at acidification levels before the end of this century. Week‐long periods of undersaturation occur for 18 mol % high‐Mg calcite after storms by the end of the century. In a high‐CO 2 world, CaCO 3 undersaturation of coral reef seawater will occur as a result of even modest tropical cyclones. The expected increase in the strength, frequency, and rainfall of the most severe tropical cyclones with climate change in combination with ocean acidification will negatively impact the structural persistence of coral reefs.