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Source and distribution characteristics of 239, 240, 241Pu, 237Np and 134, 137Cs in sediments in the Northwest and Central Equatorial Pacific after the Fukushima nuclear accident 全文
2022
Wang, Fenfen | Zheng, Jian | Aono, Tatsuo | Pan, Shaoming | Men, Wu
To understand the possible influence of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident on the deep sea, as well as the geochemical behavior and transport of radionuclides, ¹³⁴Cs, ¹³⁷Cs, ²³⁹, ²⁴⁰Pu, ²⁴¹Pu, and ²³⁷Np were measured in the abyssal sediments of the Northwest Pacific (NWP) and Central Equatorial Pacific (CEP) Ocean. Data on the characteristics of these sediments obtained after the FDNPP accident are extremely rare, especially in the NWP subtropical gyre (NPSG) region. FDNPP-derived radio-Cs (¹³⁴Cs, ¹³⁷Cs) arrived at the open sea floor of the NWP before 2018 but was only found in the Kuroshio-Oyashio Extension (KOE) region. No FDNPP-derived Pu was detected in the abyssal sediments of the NWP or CEP. Pu in the NWP mainly originated from global fallout and the Pacific Proving Ground (PPG) close-in fallout, except for at station WP1 (39°N in the KOE region), where an abnormal but non-FDNPP-derived Pu signal was detected. Pu in the eastern CEP sediment was less affected by the PPG close-in fallout from the Marshall Islands and was mainly derived from global fallout, with some close-in fallout from the Johnston Atoll test. The KOE region was the area most affected by PPG close-in fallout Pu via Kuroshio transport, while the lowest inventories of ²³⁹⁺²⁴⁰Pu and ²³⁷Np were found in the NPSG region due to its oligotrophic environment. The ²³⁷Np originated from the same source as Pu, and the latitudinal pattern of ²³⁷Np was consistent with that of Pu. Station SS (in the marginal sea of the NWP) contained high ²³⁷Np/²³⁹Pu atom ratios in the deeper layers of sediment and had a ²³⁷Np depth profile opposite that of the ²³⁹⁺²⁴⁰Pu profile, compared to other stations; these differences are mainly attributed to differences in the behaviors of ²³⁷Np and ²³⁹Pu.
显示更多 [+] 显示较少 [-]Sea turtles across the North Pacific are exposed to perfluoroalkyl substances 全文
2021
Wood, Cathryn | Balazs, George H. | Rice, Marc | Work, Thierry M. | Jones, T Todd | Sterling, Eleanor | Summers, Tammy M. | Brooker, John | Kurpita, Lauren | King, Cheryl S. | Lynch, Jennifer M.
Perfluorinated alkyl substances (PFASs) are global, persistent, and toxic contaminants. We assessed PFAS concentrations in green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtles from the North Pacific. Fifteen compounds were quantified via liquid chromatography tandem mass spectrometry from 62 green turtle and 6 hawksbill plasma samples from Hawai’i, Palmyra Atoll, and the Northern Marianas Islands. Plasma from 14 green turtles severely afflicted with fibropapillomatosis, and eggs from 12 Hawaiian hawksbill nests from 7 females were analyzed. Perfluorooctane sulfonate (PFOS) predominated in green turtle plasma; perfluorononanoic acid (PFNA) predominated in hawksbill tissues. Concentrations were greater in hawksbill than green turtle plasma (p < 0.05), related to trophic differences. Green turtle plasma PFOS concentrations were related to human populations from highest to lowest: Hawai’i, Marianas, Palmyra. Influence on fibropapillomatosis was not evident. PFASs were maternally transferred to hawksbill eggs, with decreasing concentrations with distance from airports and with clutch order from one female. A risk assessment of PFOS showed concern for immunosuppression in Kailua green turtles and alarming concern for hawksbill developmental toxicity. Perfluoroundecanoic (PFUnA) and perfluorotridecanoic (PFTriA) acid levels were correlated with reduced emergence success (p < 0.05). Studies to further examine PFAS effects on sea turtle development would be beneficial.
显示更多 [+] 显示较少 [-]First detection of microplastics in reef-building corals from a Maldivian atoll 全文
2022
Raguso, Clarissa | Saliu, Francesco | Lasagni, Marina | Galli, Paolo | Clemenza, Massimiliano | Montano, Simone
The presence of microplastics in the world's oceans and their effects on marine habitats are highly concerning. As suspension-feeders, corals are very exposed to microplastics, compromising the health of coral reef ecosystems. In this study we surveyed for the first time the presence of microplastics in Maldivian reef-building corals. Aiming to determine the influence of exposure and depth on microplastic distribution, analyses were carried out on 38 individuals belonging to three different species. 58% of the investigated colonies resulted contaminated with particles within the 25–150 μm size range. The maximum concentration was encountered in a Pocillopora verrucosa colony sampled from a shallow inner reef (8.9 particles/g of coral). No significant differences in microplastic concentration were observed between different depths, exposures, sites and species. Overall, this study confirmed microplastic presence in coral reefs of the Maldivian archipelago including foundation species.
显示更多 [+] 显示较少 [-]Dynamic Energy Budget model suggests feeding constraints and physiological stress in black-lip pearl oysters, 5 years post mass-mortality event 全文
2021
Monaco, Cristián J. | Sangare, Nathanael | Le Moullac, Gilles | Basset, Caline | Belliard, Corinne | Mizuno, Keiichi | Smith, Diane L. | Lo-Yat, Alain
Dynamic Energy Budget model suggests feeding constraints and physiological stress in black-lip pearl oysters, 5 years post mass-mortality event 全文
2021
Monaco, Cristián J. | Sangare, Nathanael | Le Moullac, Gilles | Basset, Caline | Belliard, Corinne | Mizuno, Keiichi | Smith, Diane L. | Lo-Yat, Alain
Mass-mortality events of marine species can disturb the structure of communities. While identifying the causes of mass-mortality events is crucial for implementing recovery strategies, monitoring is challenging in remote locations. Black-lip pearl oysters (Pinctada margaritifera) are farmed for producing black pearls within remote atolls of French Polynesia. Previous mass-mortality events have resulted in the collapse of oysters and other species; however, the causes and conditions that favour recovery are unclear. We investigated the potential for oyster population recovery 5 years after a mortality event at Takaroa Atoll (Tuamotu Archipelago). Temperature, food availability (total chlorophyll-a), growth and reproduction were monitored. Growth was also simulated using a Dynamic Energy Budget model. Despite favourable conditions, reduced growth and reproduction signalled an energetic deficit. The model overpredicted growth, and supported the hypotheses that individuals are unable to profit from the phytoplankton available and maintenance costs are high in Takaroa, ultimately explaining their poor physiological condition.
显示更多 [+] 显示较少 [-]Dynamic Energy Budget model suggests feeding constraints and physiological stress in black-lip pearl oysters, 5 years post mass-mortality event 全文
2021
Monaco, Cristian | Sangare, Nathanael | Le Moullac, Gilles | Basset, Caline | Belliard, Corinne | Mizuno, Keiichi | Smith, Diane L. | Lo-yat, Alain
Mass-mortality events of marine species can disturb the structure of communities. While identifying the causes of mass-mortality events is crucial for implementing recovery strategies, monitoring is challenging in remote locations. Black-lip pearl oysters (Pinctada margaritifera) are farmed for producing black pearls within remote atolls of French Polynesia. Previous mass-mortality events have resulted in the collapse of oysters and other species; however, the causes and conditions that favour recovery are unclear. We investigated the potential for oyster population recovery 5 years after a mortality event at Takaroa Atoll (Tuamotu Archipelago). Temperature, food availability (total chlorophyll-a), growth and reproduction were monitored. Growth was also simulated using a Dynamic Energy Budget model. Despite favourable conditions, reduced growth and reproduction signalled an energetic deficit. The model overpredicted growth, and supported the hypotheses that individuals are unable to profit from the phytoplankton available and maintenance costs are high in Takaroa, ultimately explaining their poor physiological condition
显示更多 [+] 显示较少 [-]The wave regimes of the Central Pacific Ocean with a focus on pearl farming atolls 全文
2021
Dutheil, Cyril | Jullien, S. | Aucan, J. | Menkes, C. | Le Gendre, R. | Andréfouët, S.
The wave regimes of the Central Pacific Ocean with a focus on pearl farming atolls 全文
2021
Dutheil, Cyril | Jullien, S. | Aucan, J. | Menkes, C. | Le Gendre, R. | Andréfouët, S.
Pearl farming sustainability in South Central Pacific (SCP) atolls strongly depends on water quality and renewal. These factors are partly controlled by the wave conditions that impact the lagoon circulation. To characterize the wave conditions around 83 SCP atolls including those hosting pearl farming activities, we used 18 years of WaveWatchIII simulation with a grid refined from 50 to 5 km resolution. Three regional wave regimes are statistically identified: two associated with long distant swells originating from mid-latitude storms, and one with local trade winds. All regimes occur with a relatively high frequency (22–44%), but with a marked seasonality. Wave conditions are also strongly modified locally during their propagation between the archipelagoes. Western and southern isolated atolls generally have a single regime all around their rims. In contrast, central Tuamotu atolls experience different regimes depending on their levels of protection. These results help understanding atoll hydrodynamics, which has implications for their management.
显示更多 [+] 显示较少 [-]The wave regimes of the Central Pacific Ocean with a focus on pearl farming atolls 全文
2021
Dutheil, Cyril | Jullien, Swen | Aucan, J. | Menkes, C. | Le Gendre, Romain | Andréfouët, S.
Pearl farming sustainability in South Central Pacific (SCP) atolls strongly depends on water quality and renewal. These factors are partly controlled by the wave conditions that impact the lagoon circulation. To characterize the wave conditions around 83 SCP atolls including those hosting pearl farming activities, we used 18 years of WaveWatchIII simulation with a grid refined from 50 to 5 km resolution. Three regional wave regimes are statistically identified: two associated with long distant swells originating from mid-latitude storms, and one with local trade winds. All regimes occur with a relatively high frequency (22–44%), but with a marked seasonality. Wave conditions are also strongly modified locally during their propagation between the archipelagoes. Western and southern isolated atolls generally have a single regime all around their rims. In contrast, central Tuamotu atolls experience different regimes depending on their levels of protection. These results help understanding atoll hydrodynamics, which has implications for their management.
显示更多 [+] 显示较少 [-]Tide and wave driven flow across the rim reef of the atoll of Raroia (Tuamotu, French Polynesia) 全文
2021
Aucan, Jerome | Desclaux, Terence | Le Gendre, Romain | Liao, Vetea | Andréfouët, Serge
Tide and wave driven flow across the rim reef of the atoll of Raroia (Tuamotu, French Polynesia) 全文
2021
Aucan, Jerome | Desclaux, Terence | Le Gendre, Romain | Liao, Vetea | Andréfouët, Serge
The currents flowing across the rim of the atoll of Raroia were investigated with a 1 year-long dataset of wave, water level and currents. Offshore waves break on the edge of the reef outside the atoll's rim and drive current into the lagoon, through the shallow hoa that cut across the rim. The additional water volume generated by this wave driven flow induces an elevation of water level throughout the atoll's lagoon and is evacuated back into the open ocean through a deep reef pass. The water level inside the atoll is also driven by astronomical tides, which enter the lagoon thought the reef pass, after undergoing a ~50% decrease in amplitude and a ~4 hour lag. Using a simple parametric model with three calibrated coefficients, we show that currents across the atoll's rim can be estimated as a function of the offshore wave conditions and the water level difference between the ocean and the lagoon.
显示更多 [+] 显示较少 [-]Tide and wave driven flow across the rim reef of the atoll of Raroia (Tuamotu, French Polynesia) 全文
2021
Aucan, Jerome | Desclaux, Terence | Le Gendre, Romain | Liao, Vetea | Andréfouët, Serge
The currents flowing across the rim of the atoll of Raroia were investigated with a 1 year-long dataset of wave, water level and currents. Offshore waves break on the edge of the reef outside the atoll's rim and drive current into the lagoon, through the shallow hoa that cut across the rim. The additional water volume generated by this wave driven flow induces an elevation of water level throughout the atoll's lagoon and is evacuated back into the open ocean through a deep reef pass. The water level inside the atoll is also driven by astronomical tides, which enter the lagoon thought the reef pass, after undergoing a ~50% decrease in amplitude and a ~4 hour lag. Using a simple parametric model with three calibrated coefficients, we show that currents across the atoll's rim can be estimated as a function of the offshore wave conditions and the water level difference between the ocean and the lagoon.
显示更多 [+] 显示较少 [-]Understanding connectivity of pearl oyster populations within Tuamotu atoll semi-closed lagoons: Cumulative insight from genetics and biophysical modelling approaches 全文
2021
Andréfouët, Serge | Le Gendre, Romain | Thomas, Yoann | Lo-Yat, Alain | Reisser, Céline M.O.
Understanding connectivity of pearl oyster populations within Tuamotu atoll semi-closed lagoons: Cumulative insight from genetics and biophysical modelling approaches 全文
2021
Andréfouët, Serge | Le Gendre, Romain | Thomas, Yoann | Lo-Yat, Alain | Reisser, Céline M.O.
Connectivity affects species demography, (meta)population dynamics, evolution, phylogeny and biogeography. Various methodological approaches are applied to measure connectivity. Biophysical modelling can explore systematically the influence of atmospheric, oceanic and ecological forcing, while genetics measures connectivity patterns within the sampling strategy limit. In the Pacific Ocean pearl farming lagoons, the activity relies on spat collecting of the black lipped pearl oyster Pinctada margaritifera occurring after the larval dispersal phase, which follows spawning from wild or farmed populations. Biophysical 3D modelling and genomic studies have both separately brought insights on within-lagoon connectivity and on the origin of spats. Here, we combined previous genetics results with new realistic biophysical modelling scenarios to elucidate connectivity in Ahe Atoll lagoon. When combined, we identified the weather sequence likely explaining the realized connectivity observations. We discuss the strengths, weaknesses, opportunities and threats of combining these two approaches considering specific pearl farming demographic connectivity questions.
显示更多 [+] 显示较少 [-]Understanding connectivity of pearl oyster populations within Tuamotu atoll semi-closed lagoons: Cumulative insight from genetics and biophysical modelling approaches 全文
2021
Andréfouët, Serge | Le Gendre, Romain | Thomas, Yoann | Lo-yat, Alain | Reisser, Celine
Connectivity affects species demography, (meta)population dynamics, evolution, phylogeny and biogeography. Various methodological approaches are applied to measure connectivity. Biophysical modelling can explore systematically the influence of atmospheric, oceanic and ecological forcing, while genetics measures connectivity patterns within the sampling strategy limit. In the Pacific Ocean pearl farming lagoons, the activity relies on spat collecting of the black lipped pearl oyster Pinctada margaritifera occurring after the larval dispersal phase, which follows spawning from wild or farmed populations. Biophysical 3D modelling and genomic studies have both separately brought insights on within-lagoon connectivity and on the origin of spats. Here, we combined previous genetics results with new realistic biophysical modelling scenarios to elucidate connectivity in Ahe Atoll lagoon. When combined, we identified the weather sequence likely explaining the realized connectivity observations. We discuss the strengths, weaknesses, opportunities and threats of combining these two approaches considering specific pearl farming demographic connectivity questions.
显示更多 [+] 显示较少 [-]Synergic effect of global thermal anomalies and local dredging activities on coral reefs of the Maldives 全文
2020
Pancrazi, Irene | Ahmed, Hassan | Cerrano, Carlo | Montefalcone, Monica
We investigated possible synergic effects on coral reefs of the local land reclamation activities in the Himmafushi Island (North Malè atoll, Maldives) and the global bleaching event that affected the Maldives in 2016. A BACI (Before-After Control-Impact) sampling design was adopted to contrast effects of dredging activities before and after the occurrence of both dredging and bleaching. The Reef Check protocol, a standardised and worldwide survey method, was applied to collect data through underwater visual surveys on corals, macro-zoobenthos, and fish communities. The bleaching in 2016 hit all the reefs investigated, but only in the reefs around Himmafushi (i.e., the impact sites) the live hard coral reduced significantly its cover and the sand deposited on reefs showed a fourfold increase. Substrate indicators (i.e., coral community and abiotic components) turned out to be more effective than macro-zoobenthos and fish in this short-term environmental impact study.
显示更多 [+] 显示较少 [-]The lagoon geomorphology of pearl farming atolls in the Central Pacific Ocean revisited using detailed bathymetry data 全文
2020
Andréfouët, S. | Genthon, P. | Pelletier, B. | Le Gendre, R. | Friot, C. | Smith, R. | Liao, V.
The lagoon geomorphology of pearl farming atolls in the Central Pacific Ocean revisited using detailed bathymetry data 全文
2020
Andréfouët, S. | Genthon, P. | Pelletier, B. | Le Gendre, R. | Friot, C. | Smith, R. | Liao, V.
The lagoons of seven French Polynesia and Cook Islands pearl farming atolls (Raroia, Takume, Mopelia, Takapoto, Ahe, Takaroa and Manihiki) were surveyed using multibeam and mono-beam sounders. From the detailed bathymetry, morphometric variables (average and maximum depth, frequency-area of depth, lagoon area and volume) are computed and compared. Remarkable geomorphological structures highlighted by bathymetric variations include deep reticulated structures and pinnacles. The seven atolls appear very different in abundance, size and density of these entities. Considering them as markers of the geological, sedimentological and eustatic processes that shape atoll lagoons, they are discussed in the context of the general theory of atoll lagoon formations involving karstic dissolution during Pleistocene or earlier low sea-level stands. In terms of pearl farming management, accurate bathymetric maps help pearl oyster wild stock assessment, development of circulation and biogeochemical models, better lagoon zoning and strategy to remove pearl farming derelict gears.
显示更多 [+] 显示较少 [-]The lagoon geomorphology of pearl farming atolls in the Central Pacific Ocean revisited using detailed bathymetry data 全文
2020
Andréfouët, S. | Genthon, P. | Pelletier, B. | Le Gendre, Romain | Friot, C. | Smith, R. | Liao, V.
The lagoons of seven French Polynesia and Cook Islands pearl farming atolls (Raroia, Takume, Mopelia, Takapoto, Ahe, Takaroa and Manihiki) were surveyed using multibeam and mono-beam sounders. From the detailed bathymetry, morphometric variables (average and maximum depth, frequency-area of depth, lagoon area and volume) are computed and compared. Remarkable geomorphological structures highlighted by bathymetric variations include deep reticulated structures and pinnacles. The seven atolls appear very different in abundance, size and density of these entities. Considering them as markers of the geological, sedimentological and eustatic processes that shape atoll lagoons, they are discussed in the context of the general theory of atoll lagoon formations involving karstic dissolution during Pleistocene or earlier low sea-level stands. In terms of pearl farming management, accurate bathymetric maps help pearl oyster wild stock assessment, development of circulation and biogeochemical models, better lagoon zoning and strategy to remove pearl farming derelict gears.
显示更多 [+] 显示较少 [-]Exceptional biodiversity of the cryptofaunal decapods in the Chagos Archipelago, central Indian Ocean 全文
2018
Head, Catherine E.I. | Bonsall, Michael B. | Jenkins, Tom L. | Koldewey, Heather | Pratchett, Morgan S. | Taylor, Michelle L. | Rogers, Alex D.
The Chagos Archipelago is geographically remote and isolated from most direct anthropogenic pressures. Here, we quantify the abundance and diversity of decapod crustaceans inhabiting dead coral colonies, representing a standardised microhabitat, across the Archipelago. Using morphological and molecular techniques we recorded 1868 decapods from 164 nominal species within 54 dead coral colonies, but total species estimates (Chao1 estimator) calculate at least 217 species. Galatheids were the most dominant taxa, though alpheids and hippolytids were also very abundant. 32% of species were rare, and 46% of species were found at only one atoll. This prevalence of rarer species has been reported in other cryptofauna studies, suggesting these assemblages maybe comprised of low-abundance species. This study provides the first estimate of diversity for reef cryptofauna in Chagos, which will serve as a useful baseline for global comparisons of coral reef biodiversity.
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