Significant contribution of the 18.6 year tidal cycle to regional coastal changes

Gratiot, Nicolas; Anthony, Edward J.; Gautier, Antoine; Gaucherel, Cédric; Proisy, Christophe; Wells, John T.

doi:10.1038/ngeo127

Cited by 122 publications

(94 citation statements)

References 25 publications

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“…These tidal currents can move beach sand and are particularly important between islands and at river mouths where flow velocities are high (Cambers 1998). In addition to the tidal cycles that occur over the short-term, a study by Gratiot et al (2008) has demonstrated that the 18.6 year nodal tidal cycle contributes significantly to regional coastal changes. Currents are important because of their role in transporting sediment, and to a smaller extent, erosion.…”

Section: Introductionmentioning

confidence: 99%

Beach Morphological Dynamics at Cocos Bay (Manzanilla), Trinidad

Darsan

2013

atgeol

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Manzanilla beach in Cocos Bay, Trinidad is a barrier beach that protects the freshwater Nariva Swamp from the marine environment of the Atlantic. Manzanilla beach is a very dynamic system owing to the open bay morphology, and exposure to the Atlantic Ocean. This study evaluated the spatial and temporal morphological and sedimentological characteristics, alongside hydrodynamic conditions operating on the beach. It investigates the beach's response to tidal cycles diurnally, from spring to neap tide, and seasonally. Data from nine sites during the period December 2005 to September 2007 are analyzed. Coastal parameters such as beach profiles, littoral data and sediment samples were obtained using standard geomorphological techniques. Beach volumetric changes that occurred over the tidal cycles are also quantified. Results indicate that wave height and wave energy were good predictors of beach change. The study showed that erosion was linked to rising tide and accretion to falling tide diurnally. Erosion occurred during spring tide conditions and accretion dominated during neap tides. Seasonally more erosion occurred in the winter period (dry season) and beach changes in the summer period (wet season) were controlled by the formation and migration of bars. Beach Morphological Dynamics at Cocos Bay (Manzanilla), TrinidadJunior Darsan rÉsUMÉ La plage de Manzanilla qui donne sur la baie des Cocos dans l'île de la Trinité est un cordon littoral qui protège le marais d' eau douce de Nariva en faisant écran entre celui-ci et l' environnement marin de l' Atlantique. Le système de la plage de Manzanilla est très dynamique en raison de la morphologie de la baie échancrée et de son exposition à l' océan Atlantique. L' étude évalue les caractéristiques sédimentologiques, morphologiques, spatiales et temporelles de la plage, ainsi que les conditions hydrodynamiques qui y sont à l' oeuvre. Elle examine l' effet sur la plage des cycles diurnes et saisonniers des marées, depuis les marées de vives-eaux jusqu'à celles de morteseaux. Les données prélevées à neuf endroits pendant la période allant de décembre 2005 à septembre 2007 sont analysées. Les paramètres côtiers, comme les profils de la plage, les données sur le littoral et les échantillons de sédiments, ont été obtenus au moyen de techniques couramment employées en géomorphologie. Les changements de volume qui sont survenus sur la plage pendant les cycles des marées sont aussi quantifiés. Les résultats révèlent que la hauteur et l' énergie des vagues sont de bons prédicteurs des changements subis par la plage. L' étude a montré que l' érosion est associée à la marée montante et l'accrétion, à la marée diurne descendante. L' érosion est survenue pendant les marées de vives-eaux et l'accrétion se produisait plus souvent durant les marées de morteseaux. Par rapport aux saisons, il y avait plus d' érosion en hiver (saison sèche) et les changements subis par la plage pendant la période estivale (saison des pluies) étaient tributaires de la formation et de la migration des barres.[...

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Section: Introductionmentioning

confidence: 99%

Beach Morphological Dynamics at Cocos Bay (Manzanilla), Trinidad

Darsan

2013

atgeol

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“…Following these criteria, it can be seen that only events since 2012 are taken from the tide gauge record. A notably stormy winter in 2013/2014 coincided with the peak of the 18.6 year tidal lunar cycle (Gratiot et al 2008;Haigh et al 2016).…”

Section: Surge Characteristicsmentioning

confidence: 99%

Flood Hazard Assessment for a Hyper-Tidal Estuary as a Function of Tide-Surge-Morphology Interaction

Lyddon

Brown

Leonardi

et al. 2018

Estuaries and Coasts

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Astronomical high tides and meteorological storm surges present a combined flood hazard to communities and infrastructure. There is a need to incorporate the impact of tide-surge interaction and the spatial and temporal variability of the combined flood hazard in flood risk assessments, especially in hyper-tidal estuaries where the consequences of tide and storm surge concurrence can be catastrophic. Delft3D-FLOW is used to assess up-estuary variability in extreme water levels for a range of historical events of different severity within the Severn Estuary, southwest England as an example. The influence of the following on flood hazard is investigated: (i) event severity, (ii) timing of the peak of a storm surge relative to tidal high water and (iii) the temporal distribution of the storm surge component (here in termed the surge skewness). Results show when modelling a local area event severity is most important control on flood hazard. Tide-surge concurrence increases flood hazard throughout the estuary. Positive surge skewness can result in a greater variability of extreme water levels and residual surge component, the effects of which are magnified up-estuary by estuarine geometry to exacerbate flood hazard. The concepts and methodology shown here can be applied to other estuaries worldwide.

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“…Coastal waters in French Guiana are extremely turbid, with visibility measured in centimeters rather than meters. Sediments from the Amazon are transported northwest to French Guiana by the Guiana Current (Muller-Karger et al 1988, Gratiot et al 2008, so coastal marine organisms here likely encounter prey primarily by smell, hearing and lateral line sense, rather than by sight (Janssen et al 1995, Montgomery et al 1995, Hartman & Abrahams 2000. Utne-Palm (2002) demonstrated that turbidity affects foraging behaviour by increasing the search time and decreasing the reactive distance, thus reducing the catchability of prey for piscivorous fishes.…”

Section: The Diet Of Goliath Groupers In Frenchmentioning

confidence: 99%

“…The marine environment off French Guiana is under the influence of the Amazon River; sediments are transported to the north of the Amazon and all along the Guiana shelf by the North Brazil Current (Gratiot et al 2008), making local marine waters extremely turbid and leading to low salinity. Although there is an abundance of marine organisms in this area, the ecology of these organisms, including goliath grouper, is poorly known.…”

Section: Goliath Grouper Epinephelus Itajaramentioning

confidence: 99%

Ontogenetic dietary and habitat shifts in goliath grouper Epinephelus itajara from French Guiana

Artéro¹,

Koenig²,

Richard³

et al. 2015

Endang. Species. Res.

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The ecology, particularly the trophic ecology, of the Critically Endangered goliath grouper Epinephelus itajara (Lichtenstein 1822) in French Guiana (France) is relatively unknown. Such information would provide a better understanding of the role that goliath groupers play in the marine ecosystem of French Guiana. This study focused on the feeding ecology of the goliath grouper through stomach-content and stable-isotope analyses of captured specimens. The dietary composition of goliath groupers in French Guiana was similar to that of goliath groupers from other areas of the species' range. However, in French Guiana, goliath groupers exhibited an ontogenetic shift in diet that has not been demonstrated elsewhere. Crustaceans, primarily crabs, were dominant in the diet of smaller individuals (<120 cm), whereas demersal fishes, particularly catfish (Siluriformes), dominated the diet of larger individuals. Analysis of δ 13 C and δ 15 N in muscle samples indicated that: (1) larger fish fed more on higher trophic levels; (2) low seasonal and spatial variation existed in the diet; and (3) an apparent migration of early juveniles occurred from mangrove areas to rocky reefs. In French Guiana, adult and juvenile goliath groupers share marine rocky habitat, and the data suggest they may avoid food competition by a shift in diet with size.

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Significant contribution of the 18.6 year tidal cycle to regional coastal changes

Cited by 122 publications

References 25 publications

Beach Morphological Dynamics at Cocos Bay (Manzanilla), Trinidad

Beach Morphological Dynamics at Cocos Bay (Manzanilla), Trinidad

Flood Hazard Assessment for a Hyper-Tidal Estuary as a Function of Tide-Surge-Morphology Interaction

Ontogenetic dietary and habitat shifts in goliath grouper Epinephelus itajara from French Guiana

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