Abstract
Reconstructing pre-industrial hurricane activity and aridity from natural archives places modern trends within the context of long-term natural variability. The first reconstruction of Atlantic hurricane activity in Jamaica was based on a sediment record previously obtained from a coastal lagoon. Specifically, an Extended Hurricane Activity (EHA) index was developed from high-resolution geochemical data that linked fluctuations in lake-level changes to rainfall variability associated with hurricane activity. Here, we analyse the same sediment core from which the EHA index was developed to assess the response of biological indicators, namely fossil diatom assemblages and sediment chlorophyll a (chl- a) concentrations, to hydrometeorological events (tropical cyclone-induced precipitation and droughts) over the past ~1500 years. The diatom assemblages responded sensitively to changes in salinity associated with lake-level changes driven by the balance of precipitation and evaporation. Aquatic production (inferred from sediment chl- a, which includes its main diagenetic products) and salinity (inferred from ITRAXTM µXRF chlorine counts) vary inversely following ca. 1300 CE, likely due to enhanced nutrient delivery from freshwater runoff during periods of elevated precipitation. Although the temporal resolution of our biological data is less-well resolved than that of the geochemical record, it generally tracks long-term trends in rainfall variability inferred by the EHA index over the past millennium. This further demonstrates the potential of using biological proxies from coastal lagoons to track past hurricane activity and aridity.
Highlights
The societal impacts of tropical cyclones, including human deaths and economic damage, have increased in recent decades
Whereas many paleo-hurricane reconstructions rely on physical sediment properties or geochemical analyses to reconstruct the frequency of tropical cyclones (Donnelly and Woodruff, 2007; Lambert et al, 2008; Liu and Fearn, 2000), only a few have demonstrated the potential of biological indicators (Hemphill-Haley, 1995; Horton and Sawai, 2010; Parsons, 1998; Peros et al, 2015)
The truest test of whether our biological proxy data are responding to past hydrometeorological events such as hurricanes and drought events is by comparison to the Extended Hurricane Activity (EHA) index of Atlantic tropical cyclones (Figure 3a), a measure of storm-induced lakelevel change derived from sediments from the same coastal lagoon
Summary
The societal impacts of tropical cyclones, including human deaths and economic damage, have increased in recent decades. Paleolimnological investigations have shown promising results for reconstructing millennia-long hurricane and drought histories of coastal and island areas of the Atlantic (Burn and Palmer, 2014; Burn et al, 2016; Donnelly and Woodruff, 2007; Lambert et al, 2008; Liu and Fearn, 2000; Peros et al, 2015). Whereas many paleo-hurricane reconstructions rely on physical sediment properties (e.g. grain size) or geochemical analyses to reconstruct the frequency of tropical cyclones (Donnelly and Woodruff, 2007; Lambert et al, 2008; Liu and Fearn, 2000), only a few have demonstrated the potential of biological indicators (Hemphill-Haley, 1995; Horton and Sawai, 2010; Parsons, 1998; Peros et al, 2015)
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