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Dongwoon Hwang - One of the best experts on this subject based on the ideXlab platform.
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Estimating the input of submarine groundwater discharge (SGD) and SGD-derived nutrients in Geoje Bay, Korea using (222)Rn-Si mass balance model.
Marine Pollution Bulletin, 2016Co-Authors: Dongwoon Hwang, Minkyu ChoiAbstract:Abstract In order to evaluate the main source of nutrients for maintaining the high production in Shellfish Farming bay, we have measured 222 Rn activities and the concentrations of nutrients in stream water, seawater, and coastal groundwater around Geoje Bay, one of the largest cultivation areas of oyster in the southern sea of Korea in April 2013. Using the 222 Rn and Si mass balance model, the residence time of bay seawater was about 5 days and the submarine groundwater discharge (SGD) into the bay was estimated to be approximately 1.8 × 10 6 m 3 d − 1 . The SGD-derived nutrient fluxes contributed approximately 54% for DIN, 5% for DIP, and 50% for DSi of total nutrient input entering into the bay. Thus, our results suggest that SGD is the major source of nutrients in Geoje Bay, and SGD-derived nutrients are very important to support the biological production of this Shellfish Farming bay.
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organic enrichment and pollution in surface sediments from Shellfish Farming in yeoja bay and gangjin bay korea
Korean Journal of Fisheries and Aquatic Sciences, 2013Co-Authors: Minkyu Choi, Dongwoon Hwang, Heegu ChoiAbstract:Organic enrichment was investigated in surface sediments from the Yeoja and Gangjin Bays of Korea, which contain dense Shellfish farms, in order to evaluate the contamination status and temporal changes in Shellfish Farming along these coasts. The degree of organic enrichment was determined using geochemical indicators (chemical oxygen demand, ignition loss, acid volatile sulfide, total organic carbon in sediments, and total nitrogen in sediments, ammonium and nitrate in pore water, and bioluminescence inhabitation for sediments). Temporal changes in organic enrichment conditions were detected by comparing our 2012 data to those previously reported from a survey conducted in 1999/2000. Organic enrichment was significantly higher in September than in May and July, in Gangjin Bay than in Yeoja Bay, and significantly higher in Shellfish farms than in reference sites not used to culture Shellfish. Ammonium concentrations in pore water were two orders of magnitude greater than nitrate concentrations, suggesting that these bays represent nitrogen-reducing environments.
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sterols as indicators of fecal pollution in sediments from Shellfish Farming areas yeoja bay and gangjin bay of korea
Korean Journal of Fisheries and Aquatic Sciences, 2013Co-Authors: Minkyu Choi, Dongwoon HwangAbstract:Eight fecal sterols were analyzed in surface sediments collected from Shellfish Farming areas in Yeoja Bay and Gangjin Bay, Korea, to evaluate sewage-derived fecal pollution. The concentrations of coprostanol, a good marker of sewage-derived organic contamination, in sediments were in the range of 10-530 ng/g-dry in Yeoja Bay, and 10-190 ng/g-dry in Gangjin Bay. Coprostanol levels were markedly higher in the inner bay than in the outer bay. These levels were lower than those reported in urbanized bays in Korea, however, they were comparable to levels in other Shellfish Farming areas including Gamak Bay. A multivariate analysis of the ratios of other sterols suggested that the sterols originated from sewage and plankton/benthos. Sewage was the dominant source at stations located close to the river mouth and wastewater treatment plant (WWTP) outfalls, and plankton/benthos was the primary source in the outer bay. These results suggest that management of point sources, e.g., WWTP as well as non-point sources, e.g., riverine inputs is important for improving the water quality in Yeoja Bay and Gangjin Bay.
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the role of submarine groundwater discharge sgd in nutrient budgets of gamak bay a Shellfish Farming bay in korea
Journal of Sea Research, 2010Co-Authors: Dongwoon Hwang, Hyuntaik OhAbstract:Abstract In order to evaluate the main source of nutrients fueling primary production in a Shellfish Farming bay (Gamak Bay) in the southern sea of Korea, we measured the concentrations of nutrients and radium isotopes in stream water, surface seawater, and coastal groundwater in May 2006, August 2006, and November 2007. Using a 226 Ra mass balance model, submarine groundwater discharge (SGD) into the bay was estimated to be 1.2–1.8 × 10 7 m 3 d − 1 (8–12 cm d − 1 ) during the three sampling periods. SGD-driven nutrient fluxes were approximately 85–90% and 10–30% of the total input fluxes for dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorous (DIP), respectively. The estimated nutrient budgets show that almost all the groundwater-borne nutrients were utilized inside the bay. Thus, our study suggests that the biological production of this Shellfish Farming bay is controlled mainly by SGD-driven nutrients.
Hyuntaik Oh - One of the best experts on this subject based on the ideXlab platform.
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the role of submarine groundwater discharge sgd in nutrient budgets of gamak bay a Shellfish Farming bay in korea
Journal of Sea Research, 2010Co-Authors: Dongwoon Hwang, Hyuntaik OhAbstract:Abstract In order to evaluate the main source of nutrients fueling primary production in a Shellfish Farming bay (Gamak Bay) in the southern sea of Korea, we measured the concentrations of nutrients and radium isotopes in stream water, surface seawater, and coastal groundwater in May 2006, August 2006, and November 2007. Using a 226 Ra mass balance model, submarine groundwater discharge (SGD) into the bay was estimated to be 1.2–1.8 × 10 7 m 3 d − 1 (8–12 cm d − 1 ) during the three sampling periods. SGD-driven nutrient fluxes were approximately 85–90% and 10–30% of the total input fluxes for dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorous (DIP), respectively. The estimated nutrient budgets show that almost all the groundwater-borne nutrients were utilized inside the bay. Thus, our study suggests that the biological production of this Shellfish Farming bay is controlled mainly by SGD-driven nutrients.
Annie Fiandrino - One of the best experts on this subject based on the ideXlab platform.
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Duality of trophic supply and hydrodynamic connectivity drives spatial patterns of Pacific oyster recruitment
Marine Ecology Progress Series, 2019Co-Authors: Franck Lagarde, Cécile Roques, Annie Fiandrino, Martin Ubertini, Emmanuelle Roque D'orbcastel, Serge Mortreux, Claude Chiantella, Delphine Bonnet, Ismaël Bernard, Marion RichardAbstract: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 and on an east-west gradient, from 2012-2014. Hydrodynamic connectivity was simulated using a numerical 3D transport model assessed with a Eulerian indicator. The supply of large umbo larvae did not differ significantly inside and outside oyster Farming areas, whereas the supply of pediveligers to sites outside Shellfish farms was structured by hydrodynamic connectivity. Inside Shellfish Farming zones, unfavorable conditions due to trophic competition with filter-feeders jeopardized their settlement. In this case, our results suggest loss of settlement competence by oyster larvae. This confirms our hypothesis of top-down trophic control by the oysters inside Farming zones of Thau lagoon in summer that fails to meet the ecological requirements of these areas as oyster nurseries. Knowledge of oyster dispersal, connectivity and recruitment in coastal lagoons will help local development of sustainable natural spat collection. On a global scale, our method could be transposed to other basins or used for other species such as mussels, clams or scallops, to better understand the spatial patterns of bivalve recruitment. Management of the oyster industry based on natural spat collection will help develop a sustainable activity, based on locally adapted oyster strains but also by reducing the risks of transferring pathogens between basins and the global carbon footprint of this industry.
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influences of sedimentation and hydrodynamics on the spatial distribution of alexandrium catenella tamarense resting cysts in a Shellfish Farming lagoon impacted by toxic blooms
Harmful Algae, 2013Co-Authors: Benjamin Genovesi, Annie Fiandrino, Andre Vaquer, David Mouillot, Thierry Laugier, Mohamed Laabir, Daniel GrzebykAbstract:Abstract Since resting cysts are a potential seeding source for blooms, the presence of these cysts in sediments is a marker of an established population for a number of harmful algal species. The spatial patterns of cyst density in relation to sediment characteristics and hydrodynamics are still largely misunderstood. This study investigated the spatial distribution of resting cysts belonging to the Alexandrium tamarense species complex (Dinophyceae) in sediments of a Mediterranean coastal lagoon (Thau Lagoon, France). This lagoon, hosting Shellfish Farming, is regularly impacted by toxic Alexandrium catenella blooms. The average cyst density across the whole lagoon was rather low,
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Influences of sedimentation and hydrodynamics on the spatial distribution of Alexandrium catenella/tamarense resting cysts in a Shellfish Farming lagoon impacted by toxic blooms
Harmful Algae, 2013Co-Authors: Benjamin Genovesi, Annie Fiandrino, Andre Vaquer, David Mouillot, Thierry Laugier, Mohamed Laabir, Daniel GrzebykAbstract:Abstract Since resting cysts are a potential seeding source for blooms, the presence of these cysts in sediments is a marker of an established population for a number of harmful algal species. The spatial patterns of cyst density in relation to sediment characteristics and hydrodynamics are still largely misunderstood. This study investigated the spatial distribution of resting cysts belonging to the Alexandrium tamarense species complex (Dinophyceae) in sediments of a Mediterranean coastal lagoon (Thau Lagoon, France). This lagoon, hosting Shellfish Farming, is regularly impacted by toxic Alexandrium catenella blooms. The average cyst density across the whole lagoon was rather low,
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Microbial contamination and management scenarios in a Mediterranean coastal lagoon (Etang de Thau, France): application of a Decision Support System within the Integrated Coastal Zone Management context.
2007Co-Authors: Lionel Loubersac, Annie Fiandrino, Valerie Derolez, Mathieu Jouan, Abdellah Lemsanni, Hélène Rey-valette, S. Mathe, S. Pagès, Chiara MocenniAbstract:1 - In the Thau lagoon (Southern Mediterranean Coast) the main anthropogenic pressure is represented by the urban development in the watershed, whilst oyster and mussel Farming represents one of the main economical activities in the region. 2 - During the last decade, the increasing organic loads from watershed and urban settlements in the lagoon surroundings have caused a diffuse contamination by faecal bacteria. Also toxic algal blooms have been occurring, impairing water quality with major impacts on Shellfish Farming, fishery and bathing. 3 - In this study, indicators and scenarios identified for the lagoon have been integrated in a Decision Support System (DSS) to evaluate the best solutions for reducing pressures and improving both water quality and ecosystem status. 4 - The watershed has been analysed with reference to indicators of pollution sources and transfer rates to the lagoon. In parallel, socio-economic indicators and descriptors of urban growth and development have been assessed. Numerical models have been run in order to simulate the lagoon hydrodynamics in relation to both meteorological factors and watershed runoff. The impact of faecal bacteria contamination has been evaluated in terms of economical losses and social conflicts, arising from the restriction of Shellfish Farming and marketing during contamination events. Finally, the DSS prototype has been applied to the lagoon in support to management and future planning.
Philippe Souchu - One of the best experts on this subject based on the ideXlab platform.
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influence of Shellfish Farming activities on the biogeochemical composition of the water column in thau lagoon
Marine Ecology Progress Series, 2001Co-Authors: Philippe Souchu, Andre Vaquer, Yves Collos, Sonia Landrein, Jeanmarc Deslouspaoli, Bertrand BibentAbstract:Thau lagoon is a Mediterranean Shellfish ecosystem with large biomasses of oysters growing in waters with high residence time due to low tidal ranges. The influence of filter feeders (oysters and their epibiota) on the spatial distribution of particulate and dissolved compounds in the water column of Thau lagoon was studied through its variation with time. In 1991/1992, daily varia- tions were investigated in pens, corridors and outside Shellfish Farming zones for nutrients, chloro- phyll a and primary production. Salinity, dissolved oxygen, nutrients, organic matter and chloro- phyll a were also monitored in surface waters inside and outside Shellfish Farming zones each week from January 1993 to March 1994. The presence of Shellfish farms led to a decrease by only a few per- cent of oxygen concentrations in their vicinity, but the mean (±SE) deficits of chlorophyll a and POC concentrations were 44 ± 4% and 26 ± 9% respectively in the eastern zone (8 m). The shift induced by filter feeders in phytoplankton composition favoured picophytoplankton with higher growth rates. But the summer increase in phytoplankton growth rate was stronger than the positive feedback due to filter feeder filtration. Summer was determinant for the growth of oysters owing to enhanced regenerated primary production. During this period, filter feeders were not food limited, while they tended to control phytoplankton biomasses and production the rest of the year. The nutrient excess in Shellfish Farming zones was highly significant, with increases of 73 ± 16, 36 ± 12 and 19 ± 8% for ammonia, phosphates and silicate respectively in the eastern zone. In the western zone, the nutrient excess was less strong by half for ammonia and phosphate, because the lower depth (4 m) allows light to reach the bottom and enables benthic macroflora to grow on nutrients of benthic origin. The decline of phytoplankton biomasses in Shellfish farms induced a decrease in the nutrient demand, especially for ammonia. This situation was likely to favour nitrification, which led during autumn to higher nitrate concentrations within Shellfish Farming zones than outside. Therefore, filter feeders were able to alter the dominant biogeochemical process in the water column by stimulating nitrifica- tion.
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influence of Shellfish Farming activities on nitrification nitrate reduction to ammonium and denitrification at the water sediment interface of the thau lagoon france
Marine Ecology Progress Series, 1997Co-Authors: Franck Gilbert, Philippe Souchu, Micheline Bianchi, Patricia BoninAbstract:The seasonal patterns of nitrification, denitrification and dissimilatory ammonium production (DAP) rates were studied in the sediment of 2 stations in the Thau lagoon (south of France). The station ZA was located within the Shellfish Farming zone and the station B was the reference site. A marked effect of Shellfish fanning on bacterial activities was observed. Spatial differences were associated with discrepancies in the organic content and the reduction state of sediments, i.e. highest reductive processes (denitrification and DAP) were noted in Shellfish Farming area, whereas the oxidative process (nitrification) was predominant outside the Farming zone. At both stations, the DAP activity increased in September (autumn) concomitant with an increase of the C/N ratio in the sediment due to the sedimentation of the summer phytoplanktonic production. Nitrification and denitrification rates exhibited maxima in November (winter) corresponding to dissolved inorganic nitrogen inputs from the surrounding land. In the Shellfish Farming site, 98 % of nitrate was reduced to NH4+ and 2 % to N2O showing that the most of the NO3- was reduced to ammonium and remained available for the ecosystem.
Andre Vaquer - One of the best experts on this subject based on the ideXlab platform.
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Influences of sedimentation and hydrodynamics on the spatial distribution of Alexandrium catenella/tamarense resting cysts in a Shellfish Farming lagoon impacted by toxic blooms
Harmful Algae, 2013Co-Authors: Benjamin Genovesi, Annie Fiandrino, Andre Vaquer, David Mouillot, Thierry Laugier, Mohamed Laabir, Daniel GrzebykAbstract:Abstract Since resting cysts are a potential seeding source for blooms, the presence of these cysts in sediments is a marker of an established population for a number of harmful algal species. The spatial patterns of cyst density in relation to sediment characteristics and hydrodynamics are still largely misunderstood. This study investigated the spatial distribution of resting cysts belonging to the Alexandrium tamarense species complex (Dinophyceae) in sediments of a Mediterranean coastal lagoon (Thau Lagoon, France). This lagoon, hosting Shellfish Farming, is regularly impacted by toxic Alexandrium catenella blooms. The average cyst density across the whole lagoon was rather low,
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influences of sedimentation and hydrodynamics on the spatial distribution of alexandrium catenella tamarense resting cysts in a Shellfish Farming lagoon impacted by toxic blooms
Harmful Algae, 2013Co-Authors: Benjamin Genovesi, Annie Fiandrino, Andre Vaquer, David Mouillot, Thierry Laugier, Mohamed Laabir, Daniel GrzebykAbstract:Abstract Since resting cysts are a potential seeding source for blooms, the presence of these cysts in sediments is a marker of an established population for a number of harmful algal species. The spatial patterns of cyst density in relation to sediment characteristics and hydrodynamics are still largely misunderstood. This study investigated the spatial distribution of resting cysts belonging to the Alexandrium tamarense species complex (Dinophyceae) in sediments of a Mediterranean coastal lagoon (Thau Lagoon, France). This lagoon, hosting Shellfish Farming, is regularly impacted by toxic Alexandrium catenella blooms. The average cyst density across the whole lagoon was rather low,
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Marine diatoms sustain growth of bivalves in a Mediterranean lagoon
Journal of Sea Research, 2012Co-Authors: Fabrice Pernet, Andre Vaquer, Nathalie Malet, Annie Pastoureaud, Claudie Quéré, Laurent DubrocaAbstract:Abstract Carbon stable isotopes and fatty acids were measured in the suspended particulate organic matter (POM) of the Thau lagoon to study its qualitative temporal changes in relation to environmental factors and to identify the food sources of bivalves over a one-yr-cycle in relation to their growth. Reciprocally, the impact of Shellfish Farming on POM was also studied. Oysters and mussels were sampled and measured for biometry, stable isotopes and fatty acid composition. Water samples were collected at two sites, both inside and outside of the Shellfish Farming area, to determine concentrations in POM, chlorophyll a (Chl a) and stable isotopes. Carbon isotopes and fatty acids in bivalves reflected seasonal changes in food sources, which varied consistently with the environment. Seasonal changes in δ13C and fatty acids in the bivalves suggested that dietary phytoplankton contribution varied according to season. Terrestrial organic matter and bacteria can contribute to the diet of bivalves during non-bloom periods. Mussels seemed to rely more on diatoms and less on terrestrial organic matter and bacteria than oysters did, particularly when phytoplankton biomass was low during the summer. Although one- and two-yr-old oysters showed similar δ13C, their fatty acid dynamics differed slightly. Periods of high growth rate in bivalves were mainly fuelled by diatoms, thus highlighting the importance of seasonal blooms of microphytoplankton during the critical period of bivalve growth and gamete production. Although there was no significant effect of Shellfish farms on Chl a and POM δ13C, consistent differences indicate that stable isotopes could be used successfully to investigate the effects of bivalve aquaculture.
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influence of Shellfish Farming activities on the biogeochemical composition of the water column in thau lagoon
Marine Ecology Progress Series, 2001Co-Authors: Philippe Souchu, Andre Vaquer, Yves Collos, Sonia Landrein, Jeanmarc Deslouspaoli, Bertrand BibentAbstract:Thau lagoon is a Mediterranean Shellfish ecosystem with large biomasses of oysters growing in waters with high residence time due to low tidal ranges. The influence of filter feeders (oysters and their epibiota) on the spatial distribution of particulate and dissolved compounds in the water column of Thau lagoon was studied through its variation with time. In 1991/1992, daily varia- tions were investigated in pens, corridors and outside Shellfish Farming zones for nutrients, chloro- phyll a and primary production. Salinity, dissolved oxygen, nutrients, organic matter and chloro- phyll a were also monitored in surface waters inside and outside Shellfish Farming zones each week from January 1993 to March 1994. The presence of Shellfish farms led to a decrease by only a few per- cent of oxygen concentrations in their vicinity, but the mean (±SE) deficits of chlorophyll a and POC concentrations were 44 ± 4% and 26 ± 9% respectively in the eastern zone (8 m). The shift induced by filter feeders in phytoplankton composition favoured picophytoplankton with higher growth rates. But the summer increase in phytoplankton growth rate was stronger than the positive feedback due to filter feeder filtration. Summer was determinant for the growth of oysters owing to enhanced regenerated primary production. During this period, filter feeders were not food limited, while they tended to control phytoplankton biomasses and production the rest of the year. The nutrient excess in Shellfish Farming zones was highly significant, with increases of 73 ± 16, 36 ± 12 and 19 ± 8% for ammonia, phosphates and silicate respectively in the eastern zone. In the western zone, the nutrient excess was less strong by half for ammonia and phosphate, because the lower depth (4 m) allows light to reach the bottom and enables benthic macroflora to grow on nutrients of benthic origin. The decline of phytoplankton biomasses in Shellfish farms induced a decrease in the nutrient demand, especially for ammonia. This situation was likely to favour nitrification, which led during autumn to higher nitrate concentrations within Shellfish Farming zones than outside. Therefore, filter feeders were able to alter the dominant biogeochemical process in the water column by stimulating nitrifica- tion.