title: Examining the utility of coral Ba/Ca as a proxy for river discharge and hydroclimate variability at Coiba Island, Gulf of Chirquí, Panamá.
abstract: Panamá's extreme hydroclimate seasonality is driven by Intertropical Convergence Zone rainfall and resulting runoff. River discharge (Q) carries terrestrially-derived barium to coastal waters that can be recorded in coral. We present a Ba/Ca record (1996-1917) generated from a Porites coral colony in the Gulf of Chiriquí near Coiba Island (Panamá) to understand regional hydroclimate. Here coral Ba/Ca is correlated to instrumental Q (R=0.67, p<0.001), producing a seasonally-resolved Reduced Major Axis regression of Ba/Ca (μmol/mol)=Q (m3/s)×0.006±0.001 (μmol/mol)(m3/s)-1+4.579±0.151. Our results support work in the neighboring Gulf of Panamá that determined seawater Ba/Ca, controlled by Q, is correlated to coral Ba/Ca (LaVigne et al., 2016). Additionally, the Coiba coral Ba/Ca records at least 5 El Niño events and identified 22 of the 37 wet seasons with below average precipitation. These data corroborate the Q proxy and provide insight into the use of coral Ba/Ca as an El Niño and drought indicator.
authors.affiliation: Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964, United States; Department of Earth and Environmental Science, Columbia University, New York, NY 10027, United States. Electronic address: lbrenner@ldeo.columbia.edu.
authors.forename: Logan D
authors.initials: LD
authors.lastname: Brenner
authors.affiliation: Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964, United States.
authors.forename: Braddock K
authors.initials: BK
authors.lastname: Linsley
authors.affiliation: Department of Environmental Earth Systems Science, Stanford University, Stanford, CA 94305, United States.
authors.forename: Robert B
authors.initials: RB
authors.lastname: Dunbar
mesh_terms: D000818:Animals; D037421:Anthozoa; D001464:Barium / Q000032:analysis*; D002118:Calcium / Q000032:analysis*; D055864:Droughts; D059000:El Nino-Southern Oscillation; D004784:Environmental Monitoring / Q000379:methods*; D062312:Islands; D010176:Panama; D045483:Rivers; D012621:Seasons; D012623:Seawater
chemical_list: D001464:Barium; D002118:Calcium
keywords: Ba/Ca; Coral; Drought; ITCZ; Panamá; Porites; River discharge