Tidal flushing and wind driven circulation of Ahe atoll lagoon (Tuamotu Archipelago, French Polynesia) from in situ observations and numerical modelling

Atolls of the World: Revisiting the Original Checklist

“…On some atolls a single passage through the rim allows the tides to jet through the lagoon, as on Ahe, French Polynesia (Dumas et al, 2012), among others, suggesting that in these locations tidal effects can be the primary mode of lagoon circulation. Such atolls can be referred to as "semi-closed."…”

Wave and tidally induced processes on Rocas Atoll: geomorphological implications and future projections

“…There is a continuum of variation in atoll hydrodynamics, functioning according to atoll morphology and physical boundary conditions (Dumas et al 2012). At larger and deep lagoon atolls, wind has been identified as the primary driver of circulation (von Arx 1948; Atkinson et al 1981;Mathieu et al 2002).…”

“…The combination of tide and wave-driven flows through the rim are critical for ecological functioning of reef systems such as renewal of water and oxygen and their uptake by corals (Hearn et al, 2001;Jokiel, 1978;Nakamori et al, 1992), removal of metabolic wastes and flushing of reef lagoons (Dumas et al, 2012;Frith and Mason, 1986;Kench, 1998a) and, the dispersal and recruitment of larvae (Abelson and Denny, 1997;Black, 1993;Hamner and Wolanski, 1988) However, depending on the local tidal setting, not all wave energy will be dissipated at the reef edge at high tide . Instead, waves may propagate onto the reef surface either as transformed incident waves, reformed waves, or wave bores (Lugo-Fernández et al, 1998a;Nelson, 1996).…”

“…Their general saucer-shape lagoon morphology can be completely closed by a continuous emerged rim, or open to the ocean by continuously submerged reef flats (Dumas et al 2012). In addition, the reef rim may present a number of passages that connect lagoon and ocean (Andréfouët et al 2001) and act as conduits of water and sediments (Kench & McLean 2004).…”

“…There have been a number of studies investigating flushing and circulation of different types of atolls such as open atolls (von Arx 1948); (Atkinson et al 1981;Tartinville et al 1997;Beach et al 2000;Kraines et al 1999), semi-closed atolls (Gallagher et al 1971;Dumas et al 2012;Kench 1998;Kench & McLean 2004), and fully closed atolls (Callaghan et al 2006;Sugandika et al 2014), however, most are subjected to microtidal regimes. There have been limited investigations of the relative importance of waves and tides on ocean-lagoon water exchange at mesotidal atolls, where the water level range can exceed 2.5 m. The objective of this study was to assess the contribution of tides and waves to the lagoon flushing of Rocas Atoll, a mesotidal South-Atlantic atoll with an almost unbroken rim.…”