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Modeling biogeochemical processes in sediments from the Rhone River prodelta area (NW Mediterranean Sea) ArchiMer
Pastor, L.; Cathalot, C.; Deflandre, B.; Viollier, E.; Soetaert, K.; Meysman, F. J. R.; Ulses, C.; Metzger, E.; Rabouille, C..
In situ oxygen microprofiles, sediment organic carbon content, and pore-water concentrations of nitrate, ammonium, iron, manganese, and sulfides obtained in sediments from the Rhone River prodelta and its adjacent continental shelf were used to constrain a numerical diagenetic model. Results showed that (1) the organic matter from the Rhone River is composed of a fraction of fresh material associated to high first-order degradation rate constants (11-33 yr(-1)); (2) the burial efficiency (burial/input ratio) in the Rh boolean AND one prodelta (within 3 km of the river outlet) can be up to 80 %, and decreases to similar to 20% on the adjacent continental shelf 10-15 km further offshore; (3) there is a large contribution of anoxic processes to total...
Tipo: Text
Ano: 2011 URL: https://archimer.ifremer.fr/doc/00303/41423/40614.pdf
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Diversity of nematode assemblages along a Mediterranean deep-sea transect OMA
Soetaert, K.; Heip, C.H.R.; Vincx, M..
The diversity of the nematode assemblages along a Mediterranean transect off Calvi, Corsica, Mediterranean Sea (depth range 160 to 1220 m) was very high. There was no clear trend in species diversity with station depth, and diversity at the station located on the continental shelf was not markedly lower than that at the deep-sea stations. However, diversity decreased with increasing depth into the sediment. As with the macrofauna, nematode assemblages in the Mediterranean is explained by a slight dominance of some species, while no species are dominant in the Bay of Biscay. Generic (between-genus) diversity was much higher than the average species diversity within genera, indicating that the high overall species diversity was not caused by large numbers of...
Tipo: Info:eu-repo/semantics/article
Ano: 1991 URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=2892
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Estimating estuarine residence times in the Westerschelde (The Netherlands) using a box model with fixed dispersion coefficients OMA
Soetaert, K.; Herman, P.M.J..
The residence time of the water masses in the Westerschelde estuary was determined using a simple compartment-model that simulates the advective-diffusive transport of a conservative dissolved substance (chlorinity). The residence time of a water parcel in the upstream part of the estuary (i.e. the time needed for this water parcel to leave the estuary) varied from about 50 days in winter to about 70 days in summer. The most seaward compartment had residence times of about 10-15 days. Dispersive coefficients that are fixed in time were able to reproduce the observed salinity distributions very well in the Westerschelde. They were obtained by calibration on observed chlorinities. It is argued that the apparent relationship of dispersive coefficients with...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Diffusion coefficients Environmental monitoring Estuarine dynamics Mathematical models Residence time Salinity profiles Water circulation ANE; Netherlands; Westerschelde.
Ano: 1995 URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=8410
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One foot in the grave: zooplankton drift into the Westerschelde estuary (The Netherlands) OMA
Soetaert, K.; Herman, P.M.J..
The net growth rate of marine zooplankton entering the Westerschelde estuary was investigated using an advective-dispersive transport model that simulates zooplankton biomass behaving conservatively in the estuary. Total biomass of marine zooplankters in the Westerschelde was much lower than what would be expected based on transport alone, indicating negative growth rates in the estuary. Including a net consumption term in the transport model allowed the estimation of total net mortality. About 3% of all marine zooplankters that enter the Westerschelde with the flood currents are retained in the estuary, where they die. On average, 5% of the total marine zooplankton biomass in the estuary died per day. Each year a net amount of about 1500 t of zooplankton...
Tipo: Info:eu-repo/semantics/article
Ano: 1994 URL: http://www.vliz.be/imisdocs/publications/227081.pdf
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The metazoan meiobenthos along the continental slope of the Goban Spur (NE Atlantic) OMA
Vanaverbeke, J.; Soetaert, K.; Heip, C.H.R.; Vanreusel, A..
The metazoan meiobenthos along the continental slope of the Goban Spur (NE Atlantic) was studied in the framework of the OMEX-programme (EC-MAST II). Meiobenthic densities, the vertical distribution of the meiobenthos in the sediment, and the biomass and generic composition of the dominant group, the nematodes, were investigated at different water depths. The meiobenthic communities along the depth gradient of the continental slope followed the usual trends: the communities were dominated by nematodes, and meiobenthic densities, total nematode biomass, and mean individual nematode weight decreased with increasing water depth. The shelf station had significantly higher densities, nematode biomass and mean individual weight than the deeper stations. The...
Tipo: Info:eu-repo/semantics/article
Ano: 1997 URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=5650
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Nematode distribution in ocean margin sediments of the Goban Spur (northeast Atlantic) in relation to sediment geochemistry OMA
Soetaert, K.; Vanaverbeke, J.; Heip, C.H.R.; Herman, P.M.J.; Middelburg, J.J.; Sandee, A.; Duineveld, G.C.A..
Nematode density along a depth gradient (206-2760 m) in the northeastern Atlantic (Goban Spur) is linearly and positively related to organic matter mineralization in the sediment. It is estimated that nematodes contribute at most 13% to total carbon turnover, and this contribution decreases with water depth. The vertical distribution of nematodes in the sediment closely follows concentration <i>vs</i> depth profiles of total nitrogen in the sediment. Both nematodes and total nitrogen tend to be more concentrated towards the surface with increasing water depth. There is no indication that nematode vertical distribution is directly influenced by the oxygen penetration in the sediment. However, it is hypothesized that the sediment oxygen...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Dissolved oxygen Ecological distribution Food availability Geochemistry Nitrogen Oxic sediments Population density Sediment chemistry Nematoda [Nematodes] ANE; Atlantic; Goban Spur.
Ano: 1997 URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=8407
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Production and consumption of biological particles in temperate tidal estuaries OMA
Heip, C.H.R.; Goosen, N.K.; Herman, P.M.J.; Kromkamp, J.; Middelburg, J.J.; Soetaert, K..
The question is reviewed whether a balance exists between production and consumption of biological particles in temperate tidal estuaries and what the relationships are between the magnitude of production and consumption processes and system carbon metabolism. The production terms considered are primary production by phytoplankton, microphytobenthos, macroalgae and vascular plants and the chemoautotrophic production, mainly by nitrifying bacteria. The consumption terms are generalized by considering pelagic and benthic mineralization, but major consumer compartments, heterotrophic bacteria, zooplankton, meiobenthos, and macrobenthos are considered in detail. The proposition that estuaries are heterotrophic systems, and become more so when nutrient inputs...
Tipo: Info:eu-repo/semantics/article
Ano: 1995 URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=8311
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Six new <i>Richtersia</i> species (Nematoda, Selachinematidae) from the Mediterranean Sea OMA
Soetaert, K.; Vincx, M..
Six new species of the genus <i>Richtersia</i> Steiner, 1916 are described from the Mediterranean Sea: <i>R. bathyalis</i> sp.n., <i>R. spinosa</i> sp.n., <i>R. heipi</i> sp.n., <i>R. mediterranea</i> sp.n., <i>R. staresensis</i> sp.n. and <i>R. coomansi</i> sp.n. Some morphological adaptations of <i>R. bathyalis, R. spinosa</i> and <i>R. heipi</i> are discussed in relation to their small body size. The structure of the stomatal region, labial region and spicules is described in detail and probably holds for the entire genus.
Tipo: Info:eu-repo/semantics/article Palavras-chave: Richtersia.
Ano: 1987 URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=7036
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The meiobenthos of the North Sea: density, biomass trends and distribution of copepod communities OMA
Huys, R.; Herman, P.M.J.; Heip, C.H.R.; Soetaert, K..
During a synoptic survey carried out in April-May 1986, 171 localities were sampled in the North Sea as delimited by the Straits of Dover in the south and approximately by the 100m isobath in the north. Meiobenthos included Nematoda, Copepoda, Turbellaria, Gastrotricha, Polychaeta, Oligochaeta, Priapulida, Kinorhyncha, Ostracoda, Halacarida, Isopoda, Tanaidacea, Bryozoa, Cnidaria, Sipunculida, Echiurida, Nemertini and Tardigrada. Nematodes were the dominant group in virtually all stations, their densities ranging from 61 to 4167 individuals. 10cm<sup>-2</sup>. Only in the Southern Bight, where nematode numbers were low, did harpacticoids sometimes represent the dominant meiobenthic taxon. There was a tendency for nematode (and total...
Tipo: Info:eu-repo/semantics/article
Ano: 1992 URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=7250
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Modeling <sup>210</sup>Pb-derived mixing activity in ocean margin sediments: diffusive versus nonlocal mixing OMA
Soetaert, K.; Herman, P.M.J.; Middelburg, J.J.; Heip, C.H.R.; deStigter, H.S.; van Weering, T.C.E.; Epping, E.; Helder, W..
The influence of sediment mixing on activity versus depth profiles of the radionuclide <sup>210</sup>Pb in the upper 20 cm of the sediments has been investigated along a depth transect (208 m-4500 m, 17 stations) in the OMEX study area (Goban Spur, NE Atlantic Ocean). A hierarchical family of bioturbation/nonlocal exchange models was derived. Each member of the hierarchy includes all processes of the previous model, and adds a one- or two-parameter process. The significance of the additional parameters is tested using a one-tailed <i>F</i>-test. It was found that (1) in five cases there is a significant improvement when direct injection of part of the flux into deeper sediment layers (nonlocal exchange) is added to the diffusive...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Chemical kinetics Continental margins Diffusion Lead 210 Modelling Sediment mixing ANE; Goban Spur.
Ano: 1996 URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=8450
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Meiofauna of a deep-sea transect off Corsica OMA
Soetaert, K.; Heip, C.H.R.; Vincx, M..
Tipo: Info:eu-repo/semantics/article
Ano: 1984 URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=7017
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Nematode assemblages of deep-sea and shelf break sites in the North Atlantic and Mediterranean Sea OMA
Soetaert, K.; Heip, C.H.R..
The nematode community structure of several shelf break and deep-sea stations in the North Atlantic and the Mediterranean is compared using data from the literature. Samples from 2 Mediterranean deep-sea canyons have a unique fauna of predatory and scavenging nematodes (e.g. <i>Synonchiella, Halichoanolaimus, Gammanema</i>) which comprise some 20 to 30% of the community, while some of the typical deep-sea genera (<i>Theristus, Acantholaimus</i>) are only marginally present. The nematode generic composition of the other sites reveals a gentle transition from the shelf break (Bay of Biscay; Mediterranean) over the slope (Mediterranean) towards the continental rise, abyssal plain and hadal depths (Bay of Biscay, Puerto Rico Trench,...
Tipo: Info:eu-repo/semantics/article
Ano: 1995 URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=8457
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Carbon flows in the Westerschelde estuary (The Netherlands) evaluated by means of an ecosystem model (MOSES) OMA
Soetaert, K.; Herman, P.M.J..
The autotrophic production and heterotrophic consumption of organic matter in the Westerschelde, a highly turbid and eutrophic estuary in the Southwest Netherlands is examined by means of a dynamic simulation model. The model describes the ecologically relevant processes in thirteen spatial compartments and adequately fits most observed data. Three autotrophic processes are included in the model. Net pelagic photosynthetic production is relatively low (average 41 gC m<sup>-2</sup> yr<sup>-1</sup>) and three spatial compartments near the turbidity maximum zone are respiratory sinks of phytoplankton biomass. According to the model, net phytobenthic primary production is more important than pelagic primary production in the upstream...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Autotrophy Carbon Carbon cycle Estuaries Estuarine dynamics Eutrophication Heterotrophy Mathematical models Mineralization Photosynthesis Primary production Trophic relationships ANE; Netherlands; Westerschelde.
Ano: 1995 URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=8417
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Meiobenthic distribution and nematode community structure in five European estuaries OMA
Soetaert, K.; Vincx, M.; Wittoeck, J.; Tulkens, M..
Meiofauna from the intertidal zone of five European estuaries (Ems, Westerschelde, Somme, Gironde, Tagus) was investigated. Samples represented a cross section of various benthic habitats from near-freshwater to marine, from pure silts to fine-sandy bottoms. The meiobenthic community comprised everywhere a fauna strongly dominated by nematodes, with meiobenthic density increasing with increasing salinity. The Ems differed from the other estuaries due to the presence of a well developed community of Copepods, Gastrotrichs, large Ciliates and/or soft-shelled Foraminiferans in some sites. The Westerschelde stood out due to the near-absence of harpacticoid copepods and, as in the Tagus, the lower meiobenthic densities in the marine part of the estuary. For...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Estuaries Intertidal environment Marine invertebrates Meiobenthos Population density Species diversity Copepoda [copepods] Gastrotricha Nematoda [Nematodes] Polychaeta [Bristle worms] ANE; Ems Estuary ANE; France; Gironde Estuary ANE; France; Picardie; Somme Estuary ANE; Netherlands; Westerschelde Portugal; Tagus R..
Ano: 1995 URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=8456
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Spatial patterns of Westerschelde meiobenthos OMA
Soetaert, K.; Vincx, M.; Wittoeck, J.; Tulkens, M.; Van Gansbeke, D..
The meiobenthic fauna of the Westerschelde, a highly polluted and physically disturbed estuary in the south-west Netherlands, was investigated. Samples were taken in spring from six transects, including the intertidal, subtidal and channel area, and located along the salinity gradient. The samples were subdivided into slices to examine the vertical distribution of meiobenthos. Meiobenthos densities were higher in the intertidal than in most permanently submersed areas; the subtidal sites below 7 salinity were nearly devoid of meiobenthic life. Nematodes were by far the most abundant meiobenthic organisms in the intertidal, but were less dominant in the other areas. Gastrotrichs, turbellarians, copepods and large ciliates were usually more numerous in the...
Tipo: Info:eu-repo/semantics/article
Ano: 1994 URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=8461
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A model of early diagenetic processes from the shelf to abyssal depths OMA
Soetaert, K.; Herman, P.M.J.; Middelburg, J.J..
We present a numerical model of sedimentary early diagenetic processes that includes oxic and anoxic mineralization. The model belongs to the new wave of early diagenesis models that account for depth-dependent bioturbation and porosity profiles; it can be used both for calculating steady-state conditions and transient simulation. It was developed to reproduce the cycling of carbon, oxygen, and nitrogen along the ocean margin; it resolves the sediment-depth profiles of carbon, oxygen, nitrate, ammonium, and other reduced substances. Organic carbon is modeled as two degradable fractions with different first-order degradation rates and nitrogen:carbon ratios, to account for the decreasing reactivity and N/C ratio of the organic matter with depth into the...
Tipo: Info:eu-repo/semantics/article
Ano: 1996 URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=8408
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Secondary production of the brackish copepod communities and their contribution to the carbon fluxes in the Westerschelde estuary (The Netherlands) OMA
Escaravage, V.; Soetaert, K..
The zooplankton community of the brackish part of the Westerschelde estuary (November 1989-October 1990) was dominated by two calanoid copepods, <i>Eurytemora affinis</i> and <i>Acartia tonsa</i>. <i>Eurytemora</i> was present during a longer period of the year and was much more important in terms of total abundances and biomasses than <i>Acartia</i>. The secondary production of these species was estimated by means of the growth rate method, using weight-specific growth rates obtained from laboratory cultures (<i>Eurytemora</i>) or from the literature (<i>Acartia</i>). Due to the substantially higher growth rates of <i>Acartia</i> compared to <i>Eurytemora</i>,...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Aquatic communities Carbon cycle Estuaries Secondary production Copepoda [copepods] ANE; Netherlands; Westerschelde.
Ano: 1995 URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=8409
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Spatial and temporal patterns of the zooplankton in the Westerschelde estuary OMA
Soetaert, K.; Van Rijswijk, P..
The invertebrate zooplankton fauna of the Westerschelde (Belgium and The Netherlands) was investigated during 2 yr by means of monthly samples along a salinity gradient. Copepods were usually the most abundant holoplanktonic metazoans except in the freshwater zone where Rotifera were most numerous. The combination of a classification technique and an ordination-regression technique proved to be a valuable tool for the analysis of such an extensive data set. The presence of 4 groups was established, representing spatially distinct populations but with temporally shifting boundaries. Few zooplankton species were truly estuarine in their distribution, but many were derived from nearby coastal waters. This intrusion of marine species started in spring,...
Tipo: Info:eu-repo/semantics/article
Ano: 1993 URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=8467
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Denitrification in marine sediments: a model study OMA
Middelburg, J.J.; Soetaert, K.; Herman, P.M.J.; Heip, C.H.R..
The rate and factors controlling denitrification in marine sediments have been investigated using a prognostic diagenetic model. The model is forced with observed carbon fluxes. bioturbation and sedimentation rates, and bottom water conditions. It can reproduce rates of aerobic mineralization, denitrification, and fluxes of oxygen, nitrate, and ammonium. The globally integrated rate of denitrification is estimated by this model to be about 230-285 Tg N yr<sup>-1</sup>, with about 100 Tg N yr<sup>-1</sup> occurring in shelf sediments. This estimate is significantly higher than literature estimates (12-89 Tg N yr<sup>-1</sup>), mainly because of a proposed upward revision of denitrification rates in slope and deep-sea...
Tipo: Info:eu-repo/semantics/article
Ano: 1996 URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=8415
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Leven in troebel water: het planktonische leven in het estuariene water OMA
Muylaert, K.; Tackx, M.; Soetaert, K..
Tipo: Info:eu-repo/semantics/article
Ano: 2001 URL: http://www.vliz.be/imisdocs/publications/280708.pdf
Registros recuperados: 28
Primeira ... 12 ... Última
 

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