Contribution of moderate climate events to atoll island building (Fakarava Atoll, French Polynesia)

Risks to future atoll habitability from climate‐driven environmental changes

“…A complex combination of physical and ecological factors determines whether an atoll island is habitable or not. These factors include: island size and the extent of safe and utilizable land area (Spennemann, 1996; Weisler, 1999); island positional stability (Aslam & Kench, 2017; Webb & Kench, 2010); elevation of shoreline and interior, determining susceptibility to wave‐driven flooding (Owen et al, 2016; Woodroffe, 2008); island shape and geomorphic components, which influence resistance to storms (Ford & Kench, 2014; Kumar et al, 2018; Spennemann, 2009); sediment composition, which influences groundwater resources and agroforestry potential; and the nature and extent of vegetation cover (Duvat, Pillet, et al, 2020; Duvat, Volto, & Salmon, 2017). Physical processes underpinning these attributes result from the interplay of a number of factors that vary across and within ocean basins (McLean & Kench, 2015).…”

Beta‐diversity within coral atolls: Terrestrial species turnover increases with cyclone frequencies

“…Furthermore, depending on the islet's location within the atoll relative to the cyclone track and the predominant current and wind directions, anything from predominantly fine sand to coarse rubble sediments are deposited (Duvat et al, 2020). The type of deposited material affects the vegetation recovery and succession, as certain plant species are better adapted to re-colonize either coarse coral rubble or fine sand deposits, which further adds to the contingency of the cyclone impact and subsequent re-colonization and regeneration patterns (Lee, 1984).…”

“…Different species of plants, birds, and reptiles on atolls also respond markedly differently to the environmental stress caused by saltwater, wind, or sediment re‐working, resulting in asymmetric local population declines and extinctions (Fosberg, 1961; McCoid, 1996; Schoener et al., 2004). Furthermore, depending on the islet's location within the atoll relative to the cyclone track and the predominant current and wind directions, anything from predominantly fine sand to coarse rubble sediments are deposited (Duvat et al., 2020). The type of deposited material affects the vegetation recovery and succession, as certain plant species are better adapted to re‐colonize either coarse coral rubble or fine sand deposits, which further adds to the contingency of the cyclone impact and subsequent re‐colonization and regeneration patterns (Lee, 1984).…”

“…Generally, the ecology and geomorphology of atolls are tightly linked to recurring catastrophic disturbances from tropical cyclones, for example, for sediment accretion, seedling dispersal, and for facilitating vegetation succession (Bayliss‐Smith, 1988; Duvat et al., 2020; Kench et al., 2018). The results of our analysis indicate that tropical cyclones are also likely drivers for the compositional turnover observed on the different islets within an atoll, thereby facilitating a heterogeneous distribution and compositional dissimilarity within the atoll landscape.…”

“…Tropical cyclone frequency varies across the tropical Indo‐Pacific and Caribbean (Basconcillo et al., 2021) and atolls are widely distributed both within and outside the tropical cyclone belts with different encounter rates even within archipelagos (Duvat et al., 2020). If tropical cyclones are a major driver of compositional dissimilarity between the islets within atolls, then the within‐atoll species turnover of atolls (i.e., between the different islets within one atoll) would be expected to increase with tropical cyclone frequency.…”