Consulta: creatorFacets:"Lett, Christophe"
Registros recuperados: 12
Data/hora: 05/06/2024 12:31:02

Biophysical modelling to investigate the effects of climate change on marine population dispersal and connectivity
Provedor de dados: 5
Autores: Lett, Christophe; Ayata, Sakina-dorothee; Huret, Martin; Irisson, Jean-olivier.
Climate may act on the dispersal and connectivity of marine populations through changes in the oceanic circulation and temperature, and by modifying species' prey and predator distributions. As dispersal and connectivity remain difficult to assess in situ, a first step in studying the effects of climate change can be achieved using biophysical models. To date, only a few biophysical models have been used for this purpose. Here we review these studies and also include results from other recent modelling efforts. We show that increased sea temperature, a major change expected under climate warming, may impact dispersal and connectivity patterns via changes in reproductive phenology (e.g., shift in the spawning season), transport (e.g., reduced pelagic larval...
Tipo: Text
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00031/14176/11522.pdf

Wind-induced variability in larval retention in a coral reef system: a biophysical modelling study in the South-West Lagoon of New Caledonia
Provedor de dados: 5
Autores: Cuif, Marion; Kaplan, David; Lefevre, Jerome; Faure, Vincent Martin; Caillaud, Matthieu; Verley, Philippe; Vigliola, Laurent; Lett, Christophe.
In the present work, a biophysical dispersal model is used to understand the role of the physical environment in determining reef fish larval dispersal patterns in the South-West Lagoon of New Caledonia. We focus on a reef fish species, the humbug damselfish Dascyllus aruanus, to investigate seasonal variability of simulated larval retention at the scale of a reef patch and at the scale of the lagoon, and to explore links between larval retention and wind variability. The model shows that retention exhibits considerable temporal variability and periodically reaches values much larger than anticipated. Non-zero larval settlement occurs over a large part of the lagoon. Nevertheless, settlement values decrease quickly away from the natal reef and mean...
Tipo: Text
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00170/28115/26326.pdf

A biophysical model of S. aurita early life history in the northern Gulf of Guinea
Provedor de dados: 5
Autores: Kone, Vamara; Lett, Christophe; Penven, Pierrick; Bourles, Bernard; Djakoure, Sandrine.
S. aurita is the most abundant small pelagic fish in the northern Gulf of Guinea. Its reproduction and recruitment depend crucially on environmental conditions. We developed a biophysical model of S. aurita early life history by coupling offline an individual-based model with the regional oceanic modeling system (ROMS). We used this model to investigate the main factors driving variability in eggs and larval dispersal and survival in the northern Gulf of Guinea. Precisely, individuals were released from different spawning areas along the coast and tracked for a period of 28 days corresponding to their planktonic phase. Individuals that remained in the coastal recruitment areas at an age more than 7 days, at which they can supposedly actively retain...
Tipo: Text
Palavras-chave: Hydrodynamic model; Individual-based model; S. aurita early life stage; Recruitment; Upwelling; Northern Gulf of Guinea.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00357/46790/46656.pdf

Linking local retention, self-recruitment, and persistence in marine metapopulations
Provedor de dados: 5
Autores: Lett, Christophe; Tri Nguyen-huu,; Cuif, Marion; Saenz-agudelo, Pablo; Kaplan, David.
Three indices of larval retention have been used in the literature to assess the tendency for self-maintenance of local marine populations: local retention (LR), self-recruitment (SR), and relative local retention (RLR). Only one of these, LR, defined as the ratio of locally produced settlement to local egg production, has a clear relationship to self-persistence of individual sites. However, SR, the ratio of locally produced settlement to settlement of all origins at a site, is generally easier to measure experimentally. We use theoretical, simulation, and empirical approaches to bridge the gap between these different indices, and demonstrate that there is a proportional relationship between SR and LR for metapopulations close to a stable state and with...
Tipo: Text
Palavras-chave: Connectivity; Larval dispersal; Lifetime egg production; Local retention; Marine reserve; Metapopulation; Network persistence; Population persistence; Self-persistence; Self-recruitment.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00275/38628/81243.pdf

Converging approaches for modeling the dispersal of propagules in air and sea
Provedor de dados: 5
Autores: Lett, Christophe; Barrier, Nicolas; Bahlali, Meissam.
Terrestrial plants seeds, spores and pollen are often dispersed by wind. Likewise, most eggs and larvae of marine organisms are dispersed by oceanic currents. It was historically believed that the spatial scale at which dispersal occurs was orders of magnitude smaller for plants than for fish. However, recent empirical estimates of seed and larval dispersal suggest that these dispersal scales are more alike than previously thought. The modeling approaches used to simulate aerial and aquatic dispersal are also converging. Similar biophysical models are developed, in which outputs of Eulerian models simulating the main physical forcing mechanism (wind or currents) are used as inputs to Lagrangian models that include biological components (such as seed...
Tipo: Text
Palavras-chave: Propagule dispersal; Aquatic dispersal; Oceanic dispersal; Marine dispersal; Aerial dispersal; Wind dispersal; Atmospheric dispersal; Biophysical model; Eulerian model; Lagrangian model.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00591/70333/68400.pdf

Spatial management can significantly reduce dFAD beachings in Indian and Atlantic Ocean tropical tuna purse seine fisheries
Provedor de dados: 5
Autores: Imzilen, Taha; Lett, Christophe; Chassot, Emmanuel; Kaplan, David.
Debris from fisheries pose significant threats to coastal marine ecosystems worldwide. Tropical tuna purse seine fisheries contribute to this problem via the construction and deployment of thousands of human-made drifting fish aggregating devices (dFADs) annually, many of which end up beaching in coastal areas. Here, we analyzed approximately 40,000 dFAD trajectories in the Indian Ocean and 12,000 dFAD trajectories in the Atlantic Ocean deployed over the decade 2008–2017 to identify where and when beachings occur. We find that there is tremendous promise for reducing beaching events by prohibiting deployments in areas most likely to lead to a beaching. For example, our results indicate that 21% to 40% (depending on effort redistribution after closure) of...
Tipo: Text
Palavras-chave: Marine pollution; Fishing debris; Coral reefs; Fish aggregating device (FAD); Ocean currents.
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00669/78060/80807.pdf

Connectivity between seamounts and coastal ecosystems in the Southwestern Indian Ocean
Provedor de dados: 5
Autores: Crochelet, Estelle; Barrier, Nicolas; Andrello, Marco; Marsac, Francis; Spadone, Aurélie; Lett, Christophe.
Understanding larval connectivity patterns is critical for marine spatial planning, particularly for designing marine protected areas and managing fisheries. Patterns of larval dispersal and connectivity can be inferred from numerical transport models at large spatial and temporal scales. We assess model-based connectivity patterns between seamounts of the Southwestern Indian Ocean (SWIO) and the coastal ecosystems of Mauritius, La Réunion, Madagascar, Mozambique and South Africa, with emphasis on three shallow seamounts (La Pérouse [LP], MAD-Ridge [MR] and Walters Shoal [WS]). Using drifter trajectory and a Lagrangian model of ichthyoplankton dispersal, we show that larvae can undertake very long dispersion, with larval distances increasing with pelagic...
Tipo: Text
Palavras-chave: Seamounts; Connectivity; Larval duration; Larval drift; Lagrangian modelling; Biophysical model; Surface drifters; Southwestern indian ocean; Ichthyop.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00613/72461/71423.pdf

Influence of Biological Factors on Connectivity Patterns for Concholepas concholepas (loco) in Chile
Provedor de dados: 5
Autores: Garavelli, Lysel; Colas, Francois; Verley, Philippe; Kaplan, David Michael; Yannicelli, Beatriz; Lett, Christophe.
In marine benthic ecosystems, larval connectivity is a major process influencing the maintenance and distribution of invertebrate populations. Larval connectivity is a complex process to study as it is determined by several interacting factors. Here we use an individual-based, biophysical model, to disentangle the effects of such factors, namely larval vertical migration, larval growth, larval mortality, adults fecundity, and habitat availability, for the marine gastropod Concholepas concholepas (loco) in Chile. Lower transport success and higher dispersal distances are observed including larval vertical migration in the model. We find an overall decrease in larval transport success to settlement areas from northern to southern Chile. This spatial gradient...
Tipo: Text
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00311/42254/74190.pdf

Modeling larval dispersal for the gilthead seabream in the northwestern Mediterranean sea
Provedor de dados: 5
Autores: Lett, Christophe; Barrier, Nicolas; Ourmières, Yann; Petit, Cécile; Labonne, Maylis; Bourjea, Jerome; Darnaude, Audrey M.
To investigate dispersal and connectivity between spawning and lagoon nursery habitats of the gilthead seabream, Sparus aurata, in the Gulf of Lions (northwestern Mediterranean Sea), we modeled the potential transport of the species’ larvae between its supposed main spawning site in the region (the Planier Island) and two of its main local nursery areas (the coastal lagoons of Thau and Salses-Leucate). Passive larval drift simulations using a dispersal biophysical model showed a large variability in the possible trajectories from spawning to nursery areas and in the predicted ages for larvae arrival on the two nursery sites. The most common ages at arrival obtained in the simulations (20–60 days) are broadly consistent with previous modeling studies but...
Tipo: Text
Palavras-chave: Sparus aurata; Gulf of Lions; Fish; Larvae; Models-hydrodynamic; Biophysical model; Connectivity; Otolith.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00513/62470/66903.pdf

Duality of trophic supply and hydrodynamic connectivity drives spatial patterns of Pacific oyster recruitment
Provedor de dados: 5
Autores: Lagarde, Franck; Fiandrino, Annie; Ubertini, Martin; Roque D'Orbcastel, Emmanuelle; Mortreux, Serge; Chiantella, Claude; Bec, Beatrice; Bonnet, Delphine; Roques, Cécile; Bernard, Ismael; Richard, Marion; Guyondet, Thomas; Pouvreau, Stephane; Lett, Christophe.
The recent discovery of Pacific oyster Crassostrea gigas (also known as Magallana gigas) spatfields in a Mediterranean lagoon intensely exploited for shellfish farming (Thau lagoon) revealed significant contrasts in spatial patterns of recruitment. We evaluated the processes that drive spatial patterns in oyster recruitment by comparing observed recruitment, simulated hydrodynamic connectivity and ecological variables. We hypothesized that spatial variability of recruitment depends on (1) hydrodynamic connectivity and (2) the ecology of the larval supply, settlement, metamorphosis, survival and biotic environmental parameters. We assessed recruitment at 6-8 experimental sites by larval sampling and spat collection inside and outside oyster farming areas...
Tipo: Text
Palavras-chave: Crassostrea gigas; Coastal lagoon; Larval ecology; Spatial patterns; Connectivity; Settlement; Recruitment; Oligotrophication.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00598/70981/69271.pdf

Recruitment of the Pacific oyster Crassostrea gigas in a shellfish-exploited Mediterranean lagoon: discovery, driving factors and a favorable environmental window
Provedor de dados: 5
Autores: Lagarde, Franck; Roque D'Orbcastel, Emmanuelle; Ubertini, Martin; Mortreux, Serge; Bernard, Ismael; Fiandrino, Annie; Chiantella, Claude; Bec, Beatrice; Roques, Cecile; Bonnet, Delphine; Miron, Gilles; Richard, Marion; Pouvreau, Stephane; Lett, Christophe.
In the context of increasing demand for environmental recovery, aquatic systems may face the challenge of evolving under oligotrophication. This is the case in Mediterranean lagoons, in particular the shellfish-farmed Thau lagoon in France, where we studied recruitment of the Pacific oyster Crassostrea gigas. Oyster spat and environmental parameters were monitored at several sampling sites for 3 yr (2012 to 2014) using an original method with a temporal overlap deployment of collectors to study pre- and post-settlement processes and to identify the best conditions for recruitment. Contrary to the ‘no Pacific oyster reproduction’ paradigm in Mediterranean lagoons, our study showed that recruitment of this introduced species is possible in the Thau lagoon at...
Tipo: Text
Palavras-chave: Crassostrea gigas; Oyster spat; Pediveliger; Metamorphosis; Recruitment; Oligo trophication; Larval ecology.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00398/50899/51672.pdf

Assessment of an environmental barrier to transport of ichthyoplankton from the southern to
Provedor de dados: 20
Autores: Lett, Christophe; Veitch, Jennifer; Van der Lingen, Carl D.; Hutchings, Larry.
The Lüderitz upwelling cell and Orange River cone (LUCORC) area, a transboundary region between South Africa and Namibia, is considered to be an environmental barrier to transport of ichthyoplankton from the southern to the northern Benguela upwelling ecosystems. We use environmental data and modelling to assess the potential mechanisms responsible for this barrier: environmental data were extracted from the 1 × 1° World Ocean Atlas 2001 database and used to build maps of annual mean salinity, temperature, chlorophyll, dissolved oxygen and nutrient concentrations; outputs of a regional circulation model were used in an individual-based model to assess the transport of passive particles from the southern to the northern Benguela. The data show no clear...
Tipo: Journal Contribution
Palavras-chave: Ichthyoplankton; Upwelling; Modelling; Coastal oceanography; Trade winds; Salinity; Hydrodynamics; Cartesian coordinates; Chlorophylls.
Ano: 2007
URL: http://hdl.handle.net/1834/4667