Ocean Acidification Accelerates Reef Bioerosion

Abstract

In the recent discussion how biotic systems may react to ocean acidification caused by the rapid rise in carbon dioxide partial pressure (pCO2) in the marine realm, substantial research is devoted to calcifiers such as stony corals. The antagonistic process – biologically induced carbonate dissolution via bioerosion – has largely been neglected. Unlike skeletal growth, we expect bioerosion by chemical means to be facilitated in a high-CO2 world. This study focuses on one of the most detrimental bioeroders, the sponge Cliona orientalis, which attacks and kills live corals on Australia’s Great Barrier Reef. Experimental exposure to lowered and elevated levels of pCO2 confirms a significant enforcement of the sponges’ bioerosion capacity with increasing pCO2 under more acidic conditions. Considering the substantial contribution of sponges to carbonate bioerosion, this finding implies that tropical reef ecosystems are facing the combined effects of weakened coral calcification and accelerated bioerosion, resulting in critical pressure on the dynamic balance between biogenic carbonate build-up and degradation.

Ocean acidification accelerates dissolution of experimental coral reef communities

“…Whereas several reefs around the world are already at the threshold between precipitation and dissolution of calcium carbonate (Silverman et al, 2009(Silverman et al, , 2014, the susceptibility of coral reefs to net dissolution in the future likely will be linked directly to the proportion of the reef covered by macrocalcifiers and sediments. In addition to dissolution, it also is possible that coral reefs will be exposed to increased bioerosion at high pCO 2 (Wisshak et al, 2012;Crook et al, 2013) that will decrease the integrity of the carbonate framework. In addition to the direct effects of OA on reef builders, the associated loss of three-dimensional framework might impact a large variety of marine organisms by reducing habitat complexity and the availability of refuges (Fabricius et al, 2014).…”

Sponge bioerosion accelerated by ocean acidification across species and latitudes?

“…Water samples for analyses were taken and processed as described in Wisshak et al (2012). Aliquots of culture water were sterile-filtered with 0.2-lm PES filters at the start (0 h), mid-way (48 h) and at the end (96 h) of the experiments.…”

“…Considering the significant environmental changes of our century, recent research activities pay renewed attention to bioerosion and question how it may be influenced by global developments, and whether it may outweigh calcification processes (e.g. Tribollet et al 2009;Andersson and Gledhill 2012;Wisshak et al 2012;Kennedy et al 2013). The traditional focus of bioerosion research lies on tropical coral reefs, with the most comprehensive data derived from the Pacific and the Caribbean (e.g.…”

Twenty Years of Marine Carbon Cycle Observations at Devils Hole Bermuda Provide Insights into Seasonal Hypoxia, Coral Reef Calcification, and Ocean Acidification

“…Studies of processes such as dissolution of reef CaCO 3 sediments (e.g., Yates and Halley, 2006;Andersson et al, 2007Andersson et al, , 2009Tribollet et al, 2009;Rao et al, 2012;Comeau et al, 2015;Rodolfo-Metalpa et al, 2015;Yamamoto et al, 2015), pore water and alkalinity fluxes from the sediment (e.g., Falter and Sansone, 2000;Santos et al, 2011Santos et al, , 2012aCyronak et al, 2013a,b), and coral bioerosion (e.g., Wisshak et al, 2012;Crook et al, 2013;Enochs et al, 2015;Kline et al, 2015) all contribute to elucidating the complex controls and responses of coral reefs to changes in ocean chemistry.…”