title: Effects of High Dissolved Inorganic and Organic Carbon Availability on the Physiology of the Hard Coral Acropora millepora from the Great Barrier Reef.
abstract: Coral reefs are facing major global and local threats due to climate change-induced increases in dissolved inorganic carbon (DIC) and because of land-derived increases in organic and inorganic nutrients. Recent research revealed that high availability of labile dissolved organic carbon (DOC) negatively affects scleractinian corals. Studies on the interplay of these factors, however, are lacking, but urgently needed to understand coral reef functioning under present and near future conditions. This experimental study investigated the individual and combined effects of ambient and high DIC (pCO2 403 μatm/ pHTotal 8.2 and 996 μatm/pHTotal 7.8) and DOC (added as Glucose 0 and 294 μmol L-1, background DOC concentration of 83 μmol L-1) availability on the physiology (net and gross photosynthesis, respiration, dark and light calcification, and growth) of the scleractinian coral Acropora millepora (Ehrenberg, 1834) from the Great Barrier Reef over a 16 day interval. High DIC availability did not affect photosynthesis, respiration and light calcification, but significantly reduced dark calcification and growth by 50 and 23%, respectively. High DOC availability reduced net and gross photosynthesis by 51% and 39%, respectively, but did not affect respiration. DOC addition did not influence calcification, but significantly increased growth by 42%. Combination of high DIC and high DOC availability did not affect photosynthesis, light calcification, respiration or growth, but significantly decreased dark calcification when compared to both controls and DIC treatments. On the ecosystem level, high DIC concentrations may lead to reduced accretion and growth of reefs dominated by Acropora that under elevated DOC concentrations will likely exhibit reduced primary production rates, ultimately leading to loss of hard substrate and reef erosion. It is therefore important to consider the potential impacts of elevated DOC and DIC simultaneously to assess real world scenarios, as multiple rather than single factors influence key physiological processes in coral reefs.
authors.affiliation: Department of Ecology, Leibniz Center for Tropical Marine Ecology (ZMT), Bremen, Germany.|Faculty of Biology and Chemistry, University of Bremen, Bremen, Germany.
authors.forename: Friedrich W
authors.initials: FW
authors.lastname: Meyer
authors.affiliation: Faculty of Biology and Chemistry, University of Bremen, Bremen, Germany.|Australian Institute of Marine Science, Townsville MC, Queensland, Australia.
authors.forename: Nikolas
authors.initials: N
authors.lastname: Vogel
authors.affiliation: School of Life, Sport and Social Sciences, Edinburgh Napier University, Edinburgh, United Kingdom.|St Abbs Marine Station, St Abbs, United Kingdom.
authors.forename: Karen
authors.initials: K
authors.lastname: Diele
authors.affiliation: Department of Ecology, Leibniz Center for Tropical Marine Ecology (ZMT), Bremen, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Kunzmann
authors.affiliation: Australian Institute of Marine Science, Townsville MC, Queensland, Australia.
authors.forename: Sven
authors.initials: S
authors.lastname: Uthicke
authors.affiliation: Department of Ecology, Leibniz Center for Tropical Marine Ecology (ZMT), Bremen, Germany.|Faculty of Biology and Chemistry, University of Bremen, Bremen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Wild
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000187:drug effects* / Q000502:physiology*; D057919:Biological Oxygen Demand Analysis; D002244:Carbon / Q000494:pharmacology*; D002254:Carbonates / Q000032:analysis; D057894:Coral Reefs; D006244:Hardness; D007287:Inorganic Chemicals / Q000494:pharmacology*; D009930:Organic Chemicals / Q000494:pharmacology*; D010100:Oxygen / Q000032:analysis; D012995:Solubility
chemical_list: D002254:Carbonates; D007287:Inorganic Chemicals; D009930:Organic Chemicals; D002244:Carbon; D010100:Oxygen