A 3700-year paleoenvironmental record from Jobos Bay, Puerto Rico: Applying multiple proxies to reconstruct late Holocene extreme events

Abstract

Puerto Rico is prone to hurricanes capable of billions of dollars in property and infrastructure damage from heavy rainfall and severe storm surge flooding. Regional historical records are sparse, limiting an understanding of past hurricane trends to enact sensible risk assessment. Sedimentological reconstructions can determine hurricane activity on centennial to millennial timescales and help establish climatological mechanisms responsible for hyperactivity periods. Multi-proxy analysis was conducted on a 209 cm core (JOB 4) extracted from Jobos Bay National Estuarine Research Reserve (JBNERR) in Southern Puerto Rico, revealing a ∼ 3700-year record. Accordingly, a marine environment existed at the site from 3700 to 3230 cal yr BP. Mangroves dominated at 3230 cal yr BP, when the site transitioned to a backbarrier swamp. Six clastic deposits of varying thickness consisting of elevated carbonate content, low organic content, and large grain size are embedded in core JOB 4. A 35 cm thick deposit (∼3230 cal yr BP) with abundant shells, shell hash, and elevated marine element concentrations (Cl, Ca, Sr, Cl/Br values) is suggestive of significant tsunami run up. The other five sand deposits (2300, 1950, 1420, 1240 cal yr BP, and ∼ 2013 CE) contain elevated marine element concentrations (Cl, Ca, Sr, Cl/Br values) with low concentrations of terrestrial (Br, Ti, Fe, Fe/Sr) elements, indicative of hurricane-induced storm surge deposits, with minimal precipitation-induced terrestrial input. The hyperactive period of ∼2300–1200 cal yr BP at JBNERR is temporally similar to several regional paleohurricane records, occurring during a period of few El Niño events. Additionally, the JBNERR record contains evidence of infrequent hurricane activity during periods of both active and inactive ENSO. This paleohurricane record suggests that ENSO behavior might not be the most significant climatological determinant controlling the risk of hurricane landfalls for Puerto Rico.