title: Basin-scale estimates of pelagic and coral reef calcification in the Red Sea and Western Indian Ocean.
abstract: Basin-scale calcification rates are highly important in assessments of the global oceanic carbon cycle. Traditionally, such estimates were based on rates of sedimentation measured with sediment traps or in deep sea cores. Here we estimated CaCO3 precipitation rates in the surface water of the Red Sea from total alkalinity depletion along their axial flow using the water flux in the straits of Bab el Mandeb. The relative contribution of coral reefs and open sea plankton were calculated by fitting a Rayleigh distillation model to the increase in the strontium to calcium ratio. We estimate the net amount of CaCO3 precipitated in the Red Sea to be 7.3 ± 0.4·10(10) kg·y(-1) of which 80 ± 5% is by pelagic calcareous plankton and 20 ± 5% is by the flourishing coastal coral reefs. This estimate for pelagic calcification rate is up to 40% higher than published sedimentary CaCO3 accumulation rates for the region. The calcification rate of the Gulf of Aden was estimated by the Rayleigh model to be ∼1/2 of the Red Sea, and in the northwestern Indian Ocean, it was smaller than our detection limit. The results of this study suggest that variations of major ions on a basin scale may potentially help in assessing long-term effects of ocean acidification on carbonate deposition by marine organisms.
authors.affiliation: The Fredy and Nadine Herrmann Institute of Earth Sciences, The Hebrew University, Jerusalem 91904, Israel; The Interuniversity Institute for Marine Sciences, Eilat 88103, Israel; and.
authors.forename: Zvi
authors.initials: Z
authors.lastname: Steiner
authors.affiliation: The Fredy and Nadine Herrmann Institute of Earth Sciences, The Hebrew University, Jerusalem 91904, Israel; The Interuniversity Institute for Marine Sciences, Eilat 88103, Israel; and.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Erez
authors.affiliation: Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Aldo
authors.initials: A
authors.lastname: Shemesh
authors.affiliation: Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Ruth
authors.initials: R
authors.lastname: Yam
authors.affiliation: The Fredy and Nadine Herrmann Institute of Earth Sciences, The Hebrew University, Jerusalem 91904, Israel;
authors.forename: Amitai
authors.initials: A
authors.lastname: Katz
authors.affiliation: The Fredy and Nadine Herrmann Institute of Earth Sciences, The Hebrew University, Jerusalem 91904, Israel; The Interuniversity Institute for Marine Sciences, Eilat 88103, Israel; and boaz.lazar@mail.huji.ac.il.
authors.forename: Boaz
authors.initials: B
authors.lastname: Lazar
mesh_terms: D000825:Animal Structures / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D037421:Anthozoa / Q000033:anatomy & histology / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D002113:Calcification, Physiologic; D002118:Calcium / Q000378:metabolism; D002119:Calcium Carbonate / Q000032:analysis*; D002245:Carbon Dioxide / Q000494:pharmacology; D011232:Chemical Precipitation; D057894:Coral Reefs; D005240:Feasibility Studies; D056908:Foraminifera / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D019015:Geologic Sediments / Q000032:analysis / Q000737:chemistry; D017752:Greenhouse Effect; D006863:Hydrogen-Ion Concentration; D019156:Indian Ocean; D010933:Plankton / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D054712:Salinity; D012623:Seawater / Q000737:chemistry*; D012995:Solubility; D013324:Strontium / Q000378:metabolism
chemical_list: D002245:Carbon Dioxide; D002119:Calcium Carbonate; D002118:Calcium; D013324:Strontium
keywords: CaCO3 precipitation; Rayleigh distillation; Red Sea; Sr/Ca; alkalinity