Coral skeletal carbon isotopes (δ13C and Δ14C) record the delivery of terrestrial carbon to the coastal waters of Puerto Rico

Coral Reefs
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Abstract

Tropical small mountainous rivers deliver a poorly quantified, but potentially significant, amount of carbon to the world's oceans. However, few historical records of land-ocean carbon transfer exist for any region on Earth. Corals have the potential to provide such records, because they draw on dissolved inorganic carbon (DIC) for calcification. In temperate systems, the stable- (??13C) and radiocarbon (??14C) isotopes of coastal DIC are influenced by the ??13C and ??14C of the DIC transported from adjacent rivers. A similar pattern should exist in tropical coastal DIC and hence coral skeletons. Here, ??13C and ??14C measurements were made in a 56-year-old Montastraea faveolata coral growing ~1 km from the mouth of the Rio Fajardo in eastern Puerto Rico. Additionally, the ??13C and ??14C values of the DIC of the Rio Fajardo and its adjacent coastal waters were measured during two wet and dry seasons. Three major findings were observed: (1) synchronous depletions of both ??13C and ??14C in the coral skeleton are annually coherent with the timing of peak river discharge, (2) riverine DIC was always more depleted in ??13C and ??14C than seawater DIC, and (3) the correlation of ??13C and ??14C was the same in both coral skeleton and the DIC of the river and coastal waters. These results indicate that coral skeletal ??13C and ??14C are recording the delivery of riverine DIC to the coastal ocean. Thus, coral records could be used to develop proxies of historical land-ocean carbon flux for many tropical regions. Such information could be invaluable for understanding the role of tropical land-ocean carbon flux in the context of land-use change and global climate change. ?? 2011 United States Geological Survey.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Coral skeletal carbon isotopes (δ13C and Δ14C) record the delivery of terrestrial carbon to the coastal waters of Puerto Rico
Series title Coral Reefs
DOI 10.1007/s00338-011-0758-y
Volume 30
Issue 3
Year Published 2011
Language English
Publisher Springer
Description 12 p.
First page 791
Last page 802
Country United States
State Puerto Rico
Online Only (Y/N) N
Additional Online Files (Y/N) N
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