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Manuel Bringue - One of the best experts on this subject based on the ideXlab platform.
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dinoflagellate cyst production in the cariaco basin a 12 5 year long Sediment Trap study
Progress in Oceanography, 2019Co-Authors: Vera Pospelova, Manuel Bringue, Eric Tappa, Robert C ThunellAbstract:Abstract Seasonal and interannual variability in dinoflagellate cyst production were assessed using a 12.5 year-long Sediment Trap time series from the Cariaco Basin (southern Caribbean Sea). This study constitutes the longest such time series published to date, providing robust patterns of variability for individual dinoflagellate cyst taxa as well as for major phytoplanktonic and (micro-)zooplanktonic groups at the site. Cyst production is interpreted in the context of physico-chemical properties measured in situ at the mooring site (primarily reflecting seasonal upwelling), and considering potential interactions with other major components of the pelagic food web (e.g., diatoms, ciliates, copepods). The time series consists in >300 Sediment Trap samples, each representing ∼14 days of Sedimentation, collected at the CARIACO station between Nov. 8, 1996 and May 19, 2009. Mass fluxes of biogenic silica, calcium carbonate and organic carbon reflect dominantly the timing and strength of wind-driven, seasonal upwelling that brings colder, nutrient-rich waters to the surface, fostering primary productivity and the export of biogenous materials to the depths. On seasonal time scales, dinoflagellate cyst production is closely coupled with upwelling strength, with higher cyst fluxes consistently observed under active upwelling conditions (average of 50.5 × 103 cysts m−2 day−1) compared to non-active upwelling intervals (29.0 × 103 cysts m−2 day−1). Year-to-year variability is characterized by a large increase in cyst production observed over the last ∼4 years of the time series (2006–2009) and minimum cyst fluxes recorded in the years 1998 and 1999, following the strong 1997/98 El Nino event. Dinoflagellate cyst assemblages are dominated by Brigantedinium spp. (59.1%), accompanied by Echinidinium delicatum (10.8%), Bitectatodinium spongium (8.4%), Spiny brown type A (2.9%) and Echinidinium spp. (2.4%). Cyst produced by both autotrophic and heterotrophic dinoflagellates generally respond positively to upwelling in the basin. Most cyst taxa are associated with active upwelling conditions (e.g., Bitectatodinium spongium, Brigantedinium spp., Echinidinium delicatum, Quinquecuspis concreta, Selenopemphix quanta, Spiny brown type C), with some showing higher fluxes under active but weak upwelling conditions (e.g., Echinidinium granulatum, Echinidinium spp., cyst of P. fukuyoi, Spiny brown type A). Other cyst taxa tend to show higher abundances at the onset of upwelling conditions (e.g., Echinidinium aculeatum, cyst of Protoperidinium stellatum) or following active upwelling intervals (e.g., Lejeunecysta marieae, Selenopemphix nephroides). The detailed response of each dinoflagellate cyst taxon to environmental variability is presented in the form of an atlas, providing photomicrographs and detailing overall monthly production, contribution to the total Trap assemblage as well as cyst production over the 12.5 years of the time series.
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Seasonal, Annual, and Inter-Annual Spiniferites Cyst Production: A Review of Sediment Trap Studies
Palynology, 2018Co-Authors: Vera Pospelova, Andrea M Price, Manuel Bringue, Svetlana Esenkulova, Karin A F Zonneveld, Maija Heikkilä, Kazumi MatsuokaAbstract:Despite the fact that dinoflagellate cysts of the diverse genus Spiniferites are abundant in coastal and estuarine Sediments worldwide, little is known about patterns of their seasonal or annual production. In this paper we review previously published data on Spiniferites cyst fluxes from eight Sediment Trap time series in estuarine (the Strait of Georgia, Saanich Inlet, Hudson Bay, Omura Bay), coastal (the Santa Barbara Basin, the Arabian Sea), and offshore (off Cape Blanc) environments. This is the first study that provides detailed inter-site comparison of dinoflagellate cysts in Sediment Traps and analyzes seasonal, annual, and inter-annual cyst production from different geographic regions. We identified that cyst fluxes of all Spiniferites species at a given location increased or decreased simultaneously in all studied Sediment Trap records. This indicates that different Spiniferites species react in a similar way to local environmental triggers at each site. Average daily total cyst fluxes recorded in the Sediment Trap time series and in the dated surface Sediment samples are greater in coastal and estuarine waters where marine primary productivity is higher. This implies that nutrient availability might be an important factor stimulating Spiniferites production. There is no uniform seasonal pattern in Spiniferites fluxes, but the timing of elevated total Spiniferites fluxes coincided with intervals of local seasonal environmental change at each site. Analyses of all Sediment Traps revealed that intervals with the highest total Spiniferites fluxes correspond to the timing and intensity of local environmental change at the sea-surface when waters had: minimal turbidity, some water column stability or stratification, availability of nutrients, and sea-ice free conditions. The multi-year Trap data record considerable inter-annual variability in Spiniferites fluxes and seasonality when environmental conditions between the years varied. A combination of factors and specific environmental conditions are required to enhance Spiniferites cyst production in each region.
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seasonal production of organic walled dinoflagellate cysts in an upwelling system a Sediment Trap study from the santa barbara basin california
Marine Micropaleontology, 2013Co-Authors: Manuel Bringue, Vera Pospelova, Dorothy K PakAbstract:Abstract Seasonal variations in dinoflagellate cyst fluxes and assemblage composition were investigated for the first time on the west coast of the United States of America. We analyzed the palynological content of an ~ two year-long (May 1995 to March 1997) fortnightly Sediment Trap time series from the Santa Barbara Basin (SBB, off Southern California), a region characterized by seasonal upwelling and high levels of primary productivity. A total of 47 dinoflagellate cyst taxa were identified in the Trap samples, with assemblages dominated by cysts produced by heterotrophic taxa. Multivariate analyses support that dinoflagellate cyst fluxes and assemblages are reliable indicators of primary productivity, and reflect sea surface temperature (SST) variations associated with upwelling in the SBB. In particular, Brigantedinium spp. are associated with active upwelling intervals (fluxes up to 127,430 cysts m − 2 day − 1 and up to 86.6% of the assemblage), when SST is lower, stratification is weaker and diatom production is maximal. Conversely, Lingulodinium machaerophorum indicates relaxed upwelling conditions (up to 9640 cysts m − 2 day − 1 and 29.9% of the assemblage) characterized by higher SST, stronger stratification and reduced primary productivity. Selenopemphix undulata is associated with colder SST in the region, whereas cyst type A abundances increase with higher SST. Thecae of potentially toxic dinoflagellates are also documented, such as Lingulodinium polyedrum and Prorocentrum micans , which are mainly recorded under conditions of higher SST and strong stratification, and Dinophysis spp. with higher fluxes between June and September of both 1995 and 1996.
Wang Jing - One of the best experts on this subject based on the ideXlab platform.
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Development, Deployment and Measurement of Streamer Sediment Trap
Coastal Engineering, 2003Co-Authors: Wang JingAbstract:In this paper, the development of streamer Sediment Trap and its applications in the studies of coastal sand transport and distribution are introduced, and the key points for the installation, deployment and measurement of streamer Sediment Trap are described in detail.
Robert C Thunell - One of the best experts on this subject based on the ideXlab platform.
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dinoflagellate cyst production in the cariaco basin a 12 5 year long Sediment Trap study
Progress in Oceanography, 2019Co-Authors: Vera Pospelova, Manuel Bringue, Eric Tappa, Robert C ThunellAbstract:Abstract Seasonal and interannual variability in dinoflagellate cyst production were assessed using a 12.5 year-long Sediment Trap time series from the Cariaco Basin (southern Caribbean Sea). This study constitutes the longest such time series published to date, providing robust patterns of variability for individual dinoflagellate cyst taxa as well as for major phytoplanktonic and (micro-)zooplanktonic groups at the site. Cyst production is interpreted in the context of physico-chemical properties measured in situ at the mooring site (primarily reflecting seasonal upwelling), and considering potential interactions with other major components of the pelagic food web (e.g., diatoms, ciliates, copepods). The time series consists in >300 Sediment Trap samples, each representing ∼14 days of Sedimentation, collected at the CARIACO station between Nov. 8, 1996 and May 19, 2009. Mass fluxes of biogenic silica, calcium carbonate and organic carbon reflect dominantly the timing and strength of wind-driven, seasonal upwelling that brings colder, nutrient-rich waters to the surface, fostering primary productivity and the export of biogenous materials to the depths. On seasonal time scales, dinoflagellate cyst production is closely coupled with upwelling strength, with higher cyst fluxes consistently observed under active upwelling conditions (average of 50.5 × 103 cysts m−2 day−1) compared to non-active upwelling intervals (29.0 × 103 cysts m−2 day−1). Year-to-year variability is characterized by a large increase in cyst production observed over the last ∼4 years of the time series (2006–2009) and minimum cyst fluxes recorded in the years 1998 and 1999, following the strong 1997/98 El Nino event. Dinoflagellate cyst assemblages are dominated by Brigantedinium spp. (59.1%), accompanied by Echinidinium delicatum (10.8%), Bitectatodinium spongium (8.4%), Spiny brown type A (2.9%) and Echinidinium spp. (2.4%). Cyst produced by both autotrophic and heterotrophic dinoflagellates generally respond positively to upwelling in the basin. Most cyst taxa are associated with active upwelling conditions (e.g., Bitectatodinium spongium, Brigantedinium spp., Echinidinium delicatum, Quinquecuspis concreta, Selenopemphix quanta, Spiny brown type C), with some showing higher fluxes under active but weak upwelling conditions (e.g., Echinidinium granulatum, Echinidinium spp., cyst of P. fukuyoi, Spiny brown type A). Other cyst taxa tend to show higher abundances at the onset of upwelling conditions (e.g., Echinidinium aculeatum, cyst of Protoperidinium stellatum) or following active upwelling intervals (e.g., Lejeunecysta marieae, Selenopemphix nephroides). The detailed response of each dinoflagellate cyst taxon to environmental variability is presented in the form of an atlas, providing photomicrographs and detailing overall monthly production, contribution to the total Trap assemblage as well as cyst production over the 12.5 years of the time series.
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calibration of the planktonic foraminiferal mg ca paleothermometer Sediment Trap results from the guaymas basin gulf of california
Paleoceanography, 2005Co-Authors: Martha C Mcconnell, Robert C ThunellAbstract:[1] The Mg/Ca ratio has been measured in two surface-dwelling species of planktonic foraminifera, Globigerinoides ruber and Globigerina bulloides, from biweekly Sediment Trap samples collected in Guaymas Basin, Gulf of California, between August 1992 and November 1997. The Guaymas Basin experiences significant seasonal changes in sea surface temperature (SST) (∼16°–33°C) and thus is an ideal location for testing the temperature dependence of Mg incorporation into foraminiferal calcite. The planktonic foraminiferal Mg/Ca ratios are directly compared with concurrent temperature measurements from the study site. The results from the Sediment Trap study reveal a strong positive correlation between SST and the Mg/Ca ratio in both G. ruber (r2 = 0.86) and G. bulloides (r2 = 0.90). The Mg/Ca ratio increases exponentially by 7% per 1°C change in temperature for G. ruber and by 6% for G. bulloides. These results indicate that the Mg/Ca ratio in G. ruber and G. bulloides accurately records the measured seasonal surface temperature cycle and interannual variability in the Guaymas Basin within ±1°C. The greatest deviation between Mg/Ca–estimated SST and observed SST occurs in the spring and fall for both species. This variability is attributed to rapidly changing hydrographic conditions and possible offset between the time of calcification and the temperature measurements. In addition, G. ruber and G. bulloides exhibit very high Mg/Ca ratios during the strong El Nino–Southern Oscillation years of 1992 and 1997, verifying their potential to record SST up to 33°C and 28°C, respectively. The trace metal data are compared with foraminiferal oxygen isotope and alkenone measurements made on the same suite of Sediment Trap samples to assess the internal consistency of these temperature proxies. Strong correlations exist between the δ18O and Mg/Ca for G. ruber (r2 = 0.86) and G. bulloides (r2 = 0.79). Similarly, sea surface temperature estimates from Mg/Ca ratios are in good agreement with alkenone-derived temperature estimates (r2 = 0.89 for G. ruber and r2 = 0.81 for G. bulloides).
Vera Pospelova - One of the best experts on this subject based on the ideXlab platform.
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dinoflagellate cyst production in the cariaco basin a 12 5 year long Sediment Trap study
Progress in Oceanography, 2019Co-Authors: Vera Pospelova, Manuel Bringue, Eric Tappa, Robert C ThunellAbstract:Abstract Seasonal and interannual variability in dinoflagellate cyst production were assessed using a 12.5 year-long Sediment Trap time series from the Cariaco Basin (southern Caribbean Sea). This study constitutes the longest such time series published to date, providing robust patterns of variability for individual dinoflagellate cyst taxa as well as for major phytoplanktonic and (micro-)zooplanktonic groups at the site. Cyst production is interpreted in the context of physico-chemical properties measured in situ at the mooring site (primarily reflecting seasonal upwelling), and considering potential interactions with other major components of the pelagic food web (e.g., diatoms, ciliates, copepods). The time series consists in >300 Sediment Trap samples, each representing ∼14 days of Sedimentation, collected at the CARIACO station between Nov. 8, 1996 and May 19, 2009. Mass fluxes of biogenic silica, calcium carbonate and organic carbon reflect dominantly the timing and strength of wind-driven, seasonal upwelling that brings colder, nutrient-rich waters to the surface, fostering primary productivity and the export of biogenous materials to the depths. On seasonal time scales, dinoflagellate cyst production is closely coupled with upwelling strength, with higher cyst fluxes consistently observed under active upwelling conditions (average of 50.5 × 103 cysts m−2 day−1) compared to non-active upwelling intervals (29.0 × 103 cysts m−2 day−1). Year-to-year variability is characterized by a large increase in cyst production observed over the last ∼4 years of the time series (2006–2009) and minimum cyst fluxes recorded in the years 1998 and 1999, following the strong 1997/98 El Nino event. Dinoflagellate cyst assemblages are dominated by Brigantedinium spp. (59.1%), accompanied by Echinidinium delicatum (10.8%), Bitectatodinium spongium (8.4%), Spiny brown type A (2.9%) and Echinidinium spp. (2.4%). Cyst produced by both autotrophic and heterotrophic dinoflagellates generally respond positively to upwelling in the basin. Most cyst taxa are associated with active upwelling conditions (e.g., Bitectatodinium spongium, Brigantedinium spp., Echinidinium delicatum, Quinquecuspis concreta, Selenopemphix quanta, Spiny brown type C), with some showing higher fluxes under active but weak upwelling conditions (e.g., Echinidinium granulatum, Echinidinium spp., cyst of P. fukuyoi, Spiny brown type A). Other cyst taxa tend to show higher abundances at the onset of upwelling conditions (e.g., Echinidinium aculeatum, cyst of Protoperidinium stellatum) or following active upwelling intervals (e.g., Lejeunecysta marieae, Selenopemphix nephroides). The detailed response of each dinoflagellate cyst taxon to environmental variability is presented in the form of an atlas, providing photomicrographs and detailing overall monthly production, contribution to the total Trap assemblage as well as cyst production over the 12.5 years of the time series.
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Seasonal, Annual, and Inter-Annual Spiniferites Cyst Production: A Review of Sediment Trap Studies
Palynology, 2018Co-Authors: Vera Pospelova, Andrea M Price, Manuel Bringue, Svetlana Esenkulova, Karin A F Zonneveld, Maija Heikkilä, Kazumi MatsuokaAbstract:Despite the fact that dinoflagellate cysts of the diverse genus Spiniferites are abundant in coastal and estuarine Sediments worldwide, little is known about patterns of their seasonal or annual production. In this paper we review previously published data on Spiniferites cyst fluxes from eight Sediment Trap time series in estuarine (the Strait of Georgia, Saanich Inlet, Hudson Bay, Omura Bay), coastal (the Santa Barbara Basin, the Arabian Sea), and offshore (off Cape Blanc) environments. This is the first study that provides detailed inter-site comparison of dinoflagellate cysts in Sediment Traps and analyzes seasonal, annual, and inter-annual cyst production from different geographic regions. We identified that cyst fluxes of all Spiniferites species at a given location increased or decreased simultaneously in all studied Sediment Trap records. This indicates that different Spiniferites species react in a similar way to local environmental triggers at each site. Average daily total cyst fluxes recorded in the Sediment Trap time series and in the dated surface Sediment samples are greater in coastal and estuarine waters where marine primary productivity is higher. This implies that nutrient availability might be an important factor stimulating Spiniferites production. There is no uniform seasonal pattern in Spiniferites fluxes, but the timing of elevated total Spiniferites fluxes coincided with intervals of local seasonal environmental change at each site. Analyses of all Sediment Traps revealed that intervals with the highest total Spiniferites fluxes correspond to the timing and intensity of local environmental change at the sea-surface when waters had: minimal turbidity, some water column stability or stratification, availability of nutrients, and sea-ice free conditions. The multi-year Trap data record considerable inter-annual variability in Spiniferites fluxes and seasonality when environmental conditions between the years varied. A combination of factors and specific environmental conditions are required to enhance Spiniferites cyst production in each region.
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seasonal production of organic walled dinoflagellate cysts in an upwelling system a Sediment Trap study from the santa barbara basin california
Marine Micropaleontology, 2013Co-Authors: Manuel Bringue, Vera Pospelova, Dorothy K PakAbstract:Abstract Seasonal variations in dinoflagellate cyst fluxes and assemblage composition were investigated for the first time on the west coast of the United States of America. We analyzed the palynological content of an ~ two year-long (May 1995 to March 1997) fortnightly Sediment Trap time series from the Santa Barbara Basin (SBB, off Southern California), a region characterized by seasonal upwelling and high levels of primary productivity. A total of 47 dinoflagellate cyst taxa were identified in the Trap samples, with assemblages dominated by cysts produced by heterotrophic taxa. Multivariate analyses support that dinoflagellate cyst fluxes and assemblages are reliable indicators of primary productivity, and reflect sea surface temperature (SST) variations associated with upwelling in the SBB. In particular, Brigantedinium spp. are associated with active upwelling intervals (fluxes up to 127,430 cysts m − 2 day − 1 and up to 86.6% of the assemblage), when SST is lower, stratification is weaker and diatom production is maximal. Conversely, Lingulodinium machaerophorum indicates relaxed upwelling conditions (up to 9640 cysts m − 2 day − 1 and 29.9% of the assemblage) characterized by higher SST, stronger stratification and reduced primary productivity. Selenopemphix undulata is associated with colder SST in the region, whereas cyst type A abundances increase with higher SST. Thecae of potentially toxic dinoflagellates are also documented, such as Lingulodinium polyedrum and Prorocentrum micans , which are mainly recorded under conditions of higher SST and strong stratification, and Dinophysis spp. with higher fluxes between June and September of both 1995 and 1996.
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high resolution Sediment Trap study of organic walled dinoflagellate cyst production and biogenic silica flux in saanich inlet bc canada
Marine Micropaleontology, 2011Co-Authors: Andrea M Price, Vera PospelovaAbstract:Abstract Dinoflagellate cyst fluxes and assemblage composition were investigated from November 2007 to February 2010 in Patricia Bay, Saanich Inlet (BC, Canada). Samples were collected using a Sediment Trap deployed at ~ 97 m water depth. The sampling interval ranged from 0.5 to 19.5 days, allowing for a high-resolution study of dinoflagellate cyst production in relation to measured environmental parameters. Ninety-six samples were collected and a total of 42 dinoflagellate cyst taxa were identified. The dinoflagellate cyst flux was very high and ranged from ~ 149,000 to ~ 2,400,000 cysts m− 2 day− 1, with an average of ~ 777,000 cysts m− 2 day− 1. Seasonal and interannual variation in cyst assemblage was recorded. It reflects changes in environmental parameters such as sea-surface temperature, sea-surface salinity, solar insolation, river discharge, and biogenic silica flux. Fluxes of cysts produced by autotrophic dinoflagellates, particularly Spiniferites spp. and Spiniferites bentorii, were greatest during winter. Spring dinoflagellate cyst assemblages were dominated by Brigantedinium spp. and Quinquecuspis concreta. In summer the assemblages were characterized by an increase of cysts produced by heterotrophic dinoflagellates, in particular by Echinidinium delicatum, E. cf. delicatum, Votadinium spinosum and cysts of Protoperidinium minutum. Multivariate statistical analysis performed on the data supports the observed seasonal trends, where winter taxa are associated with low sea-surface temperatures, low salinity, and high Cowichan River discharge, whereas summer taxa are associated with warmer sea-surface temperatures, higher solar insolation and increased biogenic silica flux. The cyst assemblage from nearby surface Sediment was shown to be very similar to an annual average Sediment Trap assemblage.
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organic walled dinoflagellate cyst production composition and flux from 1996 to 1998 in the central strait of georgia bc canada a Sediment Trap study
Marine Micropaleontology, 2010Co-Authors: Vera Pospelova, Svetlana Esenkulova, Sophia C Johannessen, Mary C Obrien, Robie W MacdonaldAbstract:Abstract Bi-weekly fluxes of dinoflagellate cysts and assemblage composition were recorded from March 1996 to January 1999 in the central part of the Strait of Georgia (BC, Canada). The study period captured the 1997–98 El Nino event, which was characterized locally by increased Fraser River discharge resulting from earlier than usual snowmelt in 1997 and warmer sea-surface temperatures in 1998. Thirty dinoflagellate cyst taxa were identified in the Sediment Trap samples. The dinoflagellate cyst flux varied from ∼ 600 to 336,200 cysts m − 2 day − 1 , with an average of 20,000 cysts m − 2 day − 1 . In general, dinoflagellate cyst flux and species composition reflected seasonal variation of water conditions in the Strait of Georgia. Throughout the study period, assemblages were dominated by cysts produced by heterotrophic dinoflagellates, such as Protoperidineaceae ( Brigantedinium spp., Quinquecuspis concreta , and Protoperidinium americanum ). The greatest abundance of cysts of the potentially toxic Alexandrium spp. was recorded in the spring of 1996. Our results demonstrate that cysts produced by heterotrophic dinoflagellates peak in June each year, during or following diatom blooms, as indicated by biogenic silica flux. Cysts produced by autotrophic taxa were most abundant during August–September. The total annual dinoflagellate cyst flux was lower in 1997 and 1998 than in 1996, mostly due to the bloom of Alexandrium spp. in 1996. Warmer sea-surface temperature and the early spring of 1998 had a positive effect on the production of both autotrophic and heterotrophic dinoflagellates as reflected in the cyst fluxes. Cyst assemblages from Sediment Trap samples were consistent with a cyst assemblage recovered from a core sample at the same site.
Juan Carlos Miquel - One of the best experts on this subject based on the ideXlab platform.
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time series measurements of 234th in water column and Sediment Trap samples from the northwestern mediterranean sea
Deep-sea Research Part Ii-topical Studies in Oceanography, 2009Co-Authors: Kirk J Cochran, Juan Carlos Miquel, Robert Armstrong, Scott W Fowler, Pere Masque, Beat Gasser, David Hirschberg, Jennifer Szlosek, Alessia Rodriguez M Y Baena, Elisabet VerdenyAbstract:Abstract Disequilibrium between 234 Th and 238 U in water column profiles has been used to estimate the settling flux of Th (and, by proxy, of particulate organic carbon); yet potentially major non-steady-state influences on 234 Th profiles are often not able to be considered in estimations of flux. We have compared temporal series of 234 Th distributions in the upper water column at both coastal and deep-water sites in the northwestern Mediterranean Sea to coeval Sediment Trap records at the same sites. We have used Sediment Trap records of 234 Th fluxes to predict temporal changes in water column 234 Th deficits and have compared the predicted deficits to those measured to determine whether the time-evolution of the two coincide. At the coastal site (327 m water depth), trends in the two estimates of water column 234 Th deficits are in fairly close agreement over the 1-month deployment during the spring bloom in 1999. In contrast, the pattern of water column 234 Th deficits is poorly predicted by Sediment Trap records at the deep-water site (DYFAMED, ∼2300 m water depth) in both 2003 and 2005. In particular, the transition from a mesotrophic to an oligotrophic system, clearly seen in Trap fluxes, is not evident in water column 234 Th profiles, which show high-frequency variability. Allowing Trapping efficiencies to vary from 100% does not reconcile the differences between Trap and water column deficit observations; we conclude that substantial lateral and vertical advective influences must be invoked to account for the differences. Advective influences are potentially greater on 234 Th fluxes derived from water column deficits relative to those obtained from Traps because the calculation of deficits in open-ocean settings is dominated by the magnitude of the “dissolved” 234 Th fraction. For observed current velocities of 5–20 cm s −1 , in one radioactive mean-life of 234 Th, the water column at the DYFAMED site can reflect 234 Th scavenging produced tens to hundreds of kilometers away. In contrast, most of the 234 Th flux collected in shallow Sediment Traps at the DFYFAMED site was in the fraction settling >200 m d −1 ; in effect the Sediment Trap can integrate the 234 Th flux over distances ∼40-fold less than water column 234 Th distributions. In some sense, Sediment Trap and water column sampling for 234 Th provide complementary pictures of 234 Th export. However, because the two methods can be dominated by different processes and are subject to different biases, their comparison must be treated with caution.
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sampling the vertical particle flux in the upper water column using a large diameter free drifting netTrap adapted to an indented rotating sphere Sediment Trap
Deep-sea Research Part Ii-topical Studies in Oceanography, 2009Co-Authors: Michael L Peterson, Cindy Lee, Stuart G. Wakeham, Joan Fabres, Ivan J Alonso, Juan Carlos MiquelAbstract:Abstract Further development of the large, surface-tethered Sediment Trap (NetTrap) employed as part of the MedFlux program is described whereby the large collection capacity of the NetTrap is combined with an Indented Rotating Sphere/Sample Carousel (IRSC) Sediment Trap (IRSC–NT). This Trap is capable of collecting particle flux either in a time series or settling velocity mode; settling velocity mode allows the collection of particles that fall within discrete settling velocity intervals. During short field deployments in the Mediterranean Sea the IRSC–NT configured in the settling velocity mode successfully collected unpoisoned samples for chemical and microbiological experiments. In addition to the development of the IRSC–NT, particle-settling behavior above and below the swimmer-excluding IRS valve was tested during on-deck experiments using a specially constructed water-tight Trap. Chemical analyses of settling materials (published elsewhere) suggested that separation of particles by settling velocity was achieved. However, due to the motion of the ship, it was not possible to directly measure particle-settling velocities within the Trap. Particle release from the IRS did not bias the apparent settling velocity spectrum. Rotation of the IRS did not engender turbulence at the surface of the sphere or within the skewed funnel below. Tests of different ball designs over the course of the MedFlux program showed that a “ridge and saddle” pattern was optimal for efficiently transferring particles under the IRS seal while still reducing swimmer entrance to the collection funnel. The large size of the IRSC–NT did not prevent it from drifting effectively with the current. Several modifications of the present design are proposed that should improve the accuracy of the settling velocity measurements.
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lipids and their oxidation products as biomarkers for carbon cycling in the northwestern mediterranean sea results from a Sediment Trap study
Marine Chemistry, 2005Co-Authors: Daphne Marchand, Juan Carlos Miquel, Jean-claude Marty, Jeanfrancois RontaniAbstract:Classical lipid biomarkers (sterols, fatty acids and pigments) and their photo-oxidation and autoxidation products were measured in Sediment Trap samples collected during the summer of 1998 at the DYFAMED time-series station in the northwestern Mediterranean Sea to investigate changes in phytoplanktonic composition and alteration of particulate organic matter (POM). The study period covered a transitional situation from bloom event to oligotrophic conditions. At the beginning of the study, the phytoplankton community appeared to be mainly composed of diatoms, prymnesiophytes, pelagophytes and dinoflagellates. During the transition to the oligotrophic period, the contribution of small cells (pico- and nanoplankton) increased. Quantification of a “pool” of oxidation products resulting from photo-oxidation and autoxidation of phytoplanktonic sterols, monounsaturated fatty acids and chlorophyll phytyl side-chain provided very useful indications concerning the alteration state of POM during the investigated period. This “pool,” composed of some oxidation products which are very sensitive (but labile) indicators and of others which are less sensitive (but more refractory), allowed us to obtain a large range of diagnostic information about organic matter behaviour. Thanks to these indicators, visible light-induced and autoxidative degradative processes, which have been virtually ignored to date owing to the lack of suitable tracers, may be easily distinguished and appear to act intensively in the northwestern Mediterranean Sea.
