Consulta: creatorFacets:"Herman, P.M.J."
Registros recuperados: 34
Data/hora: 01/06/2024 07:32:36

Production of &lt;i&gt;Tachidius discipes&lt;/i&gt; (Copepoda: Harpacticoida)
Provedor de dados: 27
Autores: Herman, P.M.J.; Heip, C.H.R.; Guillemijn, B.
The secondary production of the harpacticoid copepod &lt;i&gt;Tachidius discipes&lt;/i&gt; Giesbrecht 1881 was estimated during spring 1979. The population was sampled every 3 d. Three generation peaks were observed. These were clearly distinct in the first copepodite stages, but gradually showed more overlap in older stages. Production of copepodites and adults was estimated in 2 ways: (1) Peaks were separated and the forward shifting of peaks in consecutive stages was used to estimate stage durations; (2) the size frequency method was applied. Both estimates of the production of copepodites and adults are in good agreement: 1.10 g dwt m&lt;sup&gt;-2&lt;/sup&gt; and 1.02 g dwt m&lt;sup&gt;-2&lt;/sup&gt;. Egg production amounts to 0.31 g dwt...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Secondary production Tachidius discipes Giesbrecht; 1881.
Ano: 1984
URL: http://www.vliz.be/imisdocs/publications/238548.pdf

Carbon flows through meiobenthic nematodes in the Westerschelde Estuary
Provedor de dados: 27
Autores: Li, J.; Vincx, M.; Herman, P.M.J.
A time dynamic model was used to estimate carbon flows through nematodes in an intertidal benthic ecosystem in the Westerschelde Estuary, The Netherlands. The model calibrated the nematode biomass observed from March 1991 to February 1992. The forcing functions of the model included meiobenthos biomass, macrobenthos biomass, bacterial density, chlorophyll-a concentration, and other abiotic data such as temperature and day length. We estimate that the nematode population had a low level of standing stock 249 mg C m(-2), but a high level of carbon flow. It consumed 98 mg C m(-2) d(-1) and produced 22 mg C m(-2) d(-1). Defecation was 73 mg C m(-2) d(-1). Losses in respiration, excretion and natural death were only 3 mg C m(-2) d(-1). The annual P/B was 32 for...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Degradation; Ecology; Marine nematodes; Meiobenthos; Respiration.
Ano: 1997
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=7296

Modeling &lt;sup&gt;210&lt;/sup&gt;Pb-derived mixing activity in ocean margin sediments: diffusive versus nonlocal mixing
Provedor de dados: 27
Autores: 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 &lt;sup&gt;210&lt;/sup&gt;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 &lt;i&gt;F&lt;/i&gt;-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

Monitoring meiobenthos using cm-, m- and km-scales in the Southern Bight of the North Sea
Provedor de dados: 27
Autores: Li, J.; Vincx, M.; Herman, P.M.J.; Heip, C.H.R.
Tipo: Info:eu-repo/semantics/article
Ano: 1997
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=7297

The fate of intertidal microphytobenthos carbon: an in situ &lt;sup&gt;13&lt;/sup&gt;C-labeling study
Provedor de dados: 27
Autores: Middelburg, J.J.; Barranguet, C.; Boschker, H.T.S.; Herman, P.M.J.; Moens, T.; Heip, C.H.R.
At two intertidal sites (one sandy and one silty, in the Scheldt estuary, The Netherlands), the fate of microphytobenthos was studied through an in situ &lt;sup&gt;13&lt;/sup&gt;C pulse- chase experiment. Label was added at the beginning of low tide, and uptake of &lt;sup&gt;13&lt;/sup&gt;C by algae was linear during the whole period of tidal exposure (about 27 mg m&lt;sup&gt;-2&lt;/sup&gt; h&lt;sup&gt;-1&lt;/sup&gt; in the top millimeter at both sites). The &lt;sup&gt;13&lt;/sup&gt;C fixed by microphytobenthos was rapidly displaced toward deeper sediment layers (down to 6 cm), in particular at the dynamic, sandy site. The residence times of microphytobenthos with respect to external losses (resuspension and respiration) were about 2.4 and 5.6 d at the...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: ANE; Netherlands; Westerschelde; Molenplaat.
Ano: 2000
URL: http://www.vliz.be/imisdocs/publications/54615.pdf

The meiobenthos of the North Sea: preliminary results of the North Sea Benthos Survey
Provedor de dados: 27
Autores: Huys, R.; Heip, C.H.R.; Herman, P.M.J.; Soetaert, K.
Tipo: Info:eu-repo/semantics/book
Ano: 1990
URL: http://www.vliz.be/imisdocs/publications/221091.pdf

A re-evaluation of marine nematode productivity
Provedor de dados: 27
Autores: Vranken, G.; Herman, P.M.J.; Vincx, M.; Heip, C.H.R.
Nematodes are the most abundant multicellular animals in marine sediments but their role in the benthos has not been properly quantified yet. In nearly all energy-flow budgets of marine systems their annual production P is given as about nine times their biomass B and their part in the total energy-flow is consequently estimated as anywhere between 3 and 30% of the total (carbon) input in the benthic system. Our laboratory experiments demonstrate that nematode productivity is much higher than P/B ~ 9 per year and may reach values of over 60 for bacterial grazers. To obtain more reliable estimates for field populations we propose a regression equation relating egg-to-egg development time T&lt;sub&gt;min&lt;/sub&gt; to temperature (t) and adult female weight...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Biological production; Mathematical models; Meiobenthos; Nematoda [Nematodes].
Ano: 1986
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3576

Assessing organic matter mineralization, degradability and mixing rate in an ocean margin sediment (Northeast Atlantic) by diagenetic modeling
Provedor de dados: 27
Autores: Soetaert, K.; Herman, P.M.J.; Middelburg, J.J.; Heip, C.H.R.
We test whether organic matter degradability, mixing activity, and total sediment mineralization can be estimated by inversion of a coupled nonlinear numerical steady-state diagenetic model. We use a single data set comprising oxygen, nitrate, ammonium and organic carbon versus depth profiles from a slope station in the Goban Spur area (1034 m, Northeast Atlantic). Based on an extensive sensitivity analysis, it appears that (1) when using all data, the total mineralization rates can be determined with reasonable precision; bioturbation and degradability are less well constrained and (2) total mineralization rates can be determined based on nitrate and oxygen profiles only; estimates of organic matter mixing rates and degradability are refined when...
Tipo: Info:eu-repo/semantics/article
Ano: 1998
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=8426

Production and consumption of biological particles in temperate tidal estuaries
Provedor de dados: 27
Autores: 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

Problems in meiofauna energy-flow studies
Provedor de dados: 27
Autores: Herman, P.M.J.; Vranken, G.; Heip, C.H.R.
The direct estimation of energy flow through marine meiobenthic populations poses several difficulties, mainly relating to sampling problems. The usefulness of some indirect estimation methods is discussed. Direct production estimates and respiration measurements for three brackish water crustacean populations are given, indicating a relative constant proportion between population production and respiration.The production: assimilation ratio for these populations fluctuates between 0.3 and 0.4. This is contrasted to literature data revealing much higher production: assimilation ratios as determined in the laboratory for nematode populations. Using data on laboratory cultures of the nematode &lt;i&gt;Monhystera disjuncta&lt;/i&gt; some factors that can...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Energy flow; Meiobenthos.
Ano: 1984
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3265

Living in the twilight: estimating net phytoplankton growth in the Westerschelde estuary (The Netherlands) by means of an ecosystem model (MOSES)
Provedor de dados: 27
Autores: Soetaert, K.; Herman, P.M.J.; Kromkamp, J.
Net phytoplankton productivity in the Westerschelde, a relatively deep. highly turbid and eutrophic estuary in the Southwest Netherlands, was examined by means of a 13-compartment dynamic simulation model. The description of the light-Iimited primary production was based on the model of Eilers and Peeters (1988. &lt;i&gt;Ecol. Model.&lt;/i&gt;, 42, 185-198). This light limitation was parameterized to the different model compartments by integrating the Eilers-Peeters model over a day and over depth taking into account the morphology of the Westerschelde compartments, the daily fluctuating light regime and characteristics of the photosynthesis-Iight curves of the phytoplankton community. The availability of light to the phytoplankters limited primary...
Tipo: Info:eu-repo/semantics/article
Ano: 1994
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=8464

The predictability of biological populations and communities: an example from the meiobenthos
Provedor de dados: 27
Autores: Herman, P.M.J.; Heip, C.H.R.
The predictability of temporal changes was analysed in the population density of three meiobenthic copepod species, and for three parameters characterizing this community. For &lt;i&gt;Paranychocamptus nanus&lt;/i&gt; and &lt;i&gt;Tachidius discipes&lt;/i&gt; a large part of the variation in time scales longer than 1 year is explainable as cyclic factors. In &lt;i&gt;P. nanus&lt;/i&gt; clear cycles with periods of 2 years and 1.5 years were found. These cyclic factors can be extrapolated for prediction. In &lt;i&gt;Canuella perplexa&lt;/i&gt; almost all the variation was due to unpredictable long-term drift. Community parameters are generally better predicted than population densities. In our data set total density of the copepods was the best parameter to...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Meiobenthos; Monitoring; Prediction; Time series; Copepoda [copepods].
Ano: 1986
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3238

Plankton size distributions and trophic relations before and after the construction of the storm-surge barrier in the Oosterschelde estuary
Provedor de dados: 27
Autores: Tackx, M.L.M.; Herman, P.M.J.; Van Rijswijk, P.; Vink, M.; Bakker, C.
Phytoplankton and zooplankton biomass distributions were calculated on a carbon basis for the inland part of the Oosterschelde, in the period before (1983), during (1984, 1986) and after (1987, 1988) the construction of the storm-surge barrier. In all years studied, both phytoplankton and zooplankton distributions are very irregular, and little consistent patterns emerge. The data were used to test the model of Sheldon et al. (1977). The observed standing stock ratios of zooplankton to phytoplankton agree with the model predictions in 1983, and are slightly higher during the period 1984-1987. In 1988, the model predictions are very different from the observed values, because of important changes in the zooplankton species abundance occurring in this year.
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Particles; Particles; Particles; Plankton; Size distribution; Spectra; Zooplankton; Netherlands.
Ano: 1994
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=2675

A model of early diagenetic processes from the shelf to abyssal depths
Provedor de dados: 27
Autores: 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

Dynamic response of deep-sea sediments to seasonal variations: a model
Provedor de dados: 27
Autores: Soetaert, K.; Herman, P.M.J.; Middelburg, J.J.
We present a dynamic, numerical model of early diagenetic processes that can be used to examine the response of different organic carbon mineralization pathways, concentration vs. depth profiles, and the resultant fluxes to seasonally varying carbon deposition. We show that there can be substantial temporal variability in sediment-water fluxes as well as in the relative contribution of different organic carbon mineralization pathways and oxygen consumption processes in deep-sea sediments. The timing and amplitude of the sediment response are most sensitive to the reactivity of the organic matter. We show that the fluxes of dissolved substances can be approximated by assuming that these constituents are at steady state with the carbon profiles. The model is...
Tipo: Info:eu-repo/semantics/article
Ano: 1996
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=8444

Studies of the life-history and energetics of marine and brackish-water nematodes: 2. Production, respiration and food uptake by &lt;i&gt;Monhystera disjuncta&lt;/i&gt;
Provedor de dados: 27
Autores: Herman, P.M.J.; Vranken, G.
An energy budget was constructed for the marine nematode &lt;i&gt;Monhystera disjuncta&lt;/i&gt;. Respiration was measured with a modified Cartesian diver technique, in which the nematodes were kept in agar inside the diver 'head'. The relationship between respiration and body weight was: R=1.53 W&lt;sup&gt;0.75&lt;/sup&gt;. Body growth was exponential during the juvenile phase, with a growth rate equal to 0.61 d&lt;sup&gt;-1&lt;/sup&gt;. After maturation the growth rate fell to 0,17 d&lt;sup&gt;-1&lt;/sup&gt;. Food uptake was measured in experiments with radiolabeled bacteria. In one series of experiments the accumulation of radiolabel in the nematodes was followed. In a second series the decrease in labeling was followed when pre-labeled nematodes fed on...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Bioenergetics; Brackishwater environment; Energy budget; Energy flow; Feeding; Life history; Meiobenthos; Respiration; Monhystera disjuncta; Nematoda [Nematodes].
Ano: 1988
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3146

Denitrification in marine sediments: a model study
Provedor de dados: 27
Autores: 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&lt;sup&gt;-1&lt;/sup&gt;, with about 100 Tg N yr&lt;sup&gt;-1&lt;/sup&gt; occurring in shelf sediments. This estimate is significantly higher than literature estimates (12-89 Tg N yr&lt;sup&gt;-1&lt;/sup&gt;), 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

Measurement of the adenylate energy charge in &lt;i&gt;Nereis diversicolor&lt;/i&gt; and &lt;i&gt;Nephtys&lt;/i&gt; sp. (Polychaeta: Annelida): evaluation of the usefulness of AEC in pollution monitoring
Provedor de dados: 27
Autores: Verschraegen, K.; Herman, P.M.J.; Van Gansbeke, D.; Braeckman, A.
ATP-content and adenylate energy charge (AEC) ratios were determined in two polychaete species (&lt;i&gt;Nereis diversicolor&lt;/i&gt; and &lt;i&gt;Nephtys&lt;/i&gt; sp.), sampled in ten stations along the heavily polluted Western Scheldt estuary (N. Belgium, S. Holland). The samples were taken between 27 December 1982 and 6 January 1983. &lt;i&gt;Nereis diversicolor&lt;/i&gt; was also sampled in an unpolluted brackish water pond, and subjected to artificial stress by drying the organisms on filter paper. Adenine nucleotide levels were determined using the firefly bioluminescence reaction. The light emission was measured with the integration mode. As the "Constant Light Signal" reagent used contained APM and probably ADP itself, both myokinase and...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: AMP ATP Efficiency Pollution monitoring Annelida [segmented worms] Nephtys Nereis diversicolor [estuary ragworm] Belgium; Zeeschelde.
Ano: 1985
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3282

Nitrogen dynamics in the Westerschelde estuary (SW Netherlands) estimated by means of the ecosystem model MOSES
Provedor de dados: 27
Autores: Soetaert, K.; Herman, P.M.J.
A tentative nitrogen budget for the Westerschelde (SW Netherlands) is constructed by means of a simulation model with thirteen spatial compartments. Biochemical and chemical processes in the water column are dynamically modeled; fluxes of dissolved constituents across the water-bottom interface are expressed by means of diagenetic equations. The model is calibrated on a large amount of observed variables in the estuary (1980-1986) with relatively fine temporal and spatial detail. Additional constraints are imposed by the stoichiometric coupling of carbon, nitrogen and oxygen flows and the required conservation of mass. The model is able to reproduce rather well the observed distributions of nitrate, ammonium, oxygen and Kjeldahl nitrogen both in time and...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Biochemical phenomena Chemical kinetics Denitrification Environmental monitoring Estuaries Mathematical models Nitrification Nitrogen Nitrogen cycle Organic matter Phytoplankton ANE; Netherlands; Westerschelde.
Ano: 1995
URL: http://www.vliz.be/imisdocs/publications/224384.pdf

The respiration of five brackish-water harpacticoid copepod species
Provedor de dados: 27
Autores: Herman, P.M.J.; Heip, C.H.R.
The dependency of respiration rate on body weight at 20°C was determined for five meiobenthic copepods from a brackish-water habitat. The respiration rate of the four smaller species was generally high, = 10-14 nl O&lt;sub&gt;2&lt;/sub&gt;.h&lt;sup&gt;-1&lt;/sup&gt;.µg dry wt&lt;sup&gt;-1&lt;/sup&gt;, but was much lower for larger species, &lt;i&gt;Canuella perplexa&lt;/i&gt; T. &amp; A. Scott 1893 (2-3 nl O&lt;sub&gt;2&lt;/sub&gt;.h&lt;sup&gt;-1&lt;/sup&gt;.µg&lt;sup&gt;1&lt;/sup&gt;). This pattern is discussed in terms of the adaptive behaviour of the populations. The significance of respiration rates in the evolution of populations is illustrated by differences between the respiration rates of Belgian &lt;i&gt;Tachidius discipes&lt;/i&gt; Giesbrecht...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Respiration; Copepoda [copepods]; Harpacticoida.
Ano: 1983
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3288

Nematode distribution in ocean margin sediments of the Goban Spur (northeast Atlantic) in relation to sediment geochemistry
Provedor de dados: 27
Autores: 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 &lt;i&gt;vs&lt;/i&gt; 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

The productivity of marine meiobenthos
Provedor de dados: 27
Autores: Heip, C.H.R.; Herman, P.M.J.; Coomans, A.
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Biological production Meiobenthos ANE; Belgium.
Ano: 1982
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=7006

Eten en gegeten worden in het Schelde-estuarium
Provedor de dados: 27
Autores: Moens, T.; Herman, P.M.J.; Ysebaert, T.J.
Tipo: Info:eu-repo/semantics/article
Ano: 2001
URL: http://www.vliz.be/imisdocs/publications/280698.pdf

The production of &lt;i&gt;Cyprideis torosa&lt;/i&gt; Jones 1850 (Crustacea, Ostracoda)
Provedor de dados: 27
Autores: Herman, P.M.J.; Heip, C.H.R.; Vranken, G.
The ostracod &lt;i&gt;Cyprideis torosa&lt;/i&gt; Jones,1985 is a dominant species in the meiofauna of brackish water habitats. Its production in the field over a five-year period has been calculated using two production models. The first model uses the age-distribution of shells preserved in the sediment to assess the stage-specific mortality rates and the stage durations. The second model is the size-frequency model, modified for use with development stages instead of size-classes. Productions calculated with both methods agree very well. Their values are 9.7 and 9.2 g dwt.m&lt;sup&gt;-2&lt;/sup&gt;y&lt;sup&gt;-1&lt;/sup&gt; respectively. The yearly P/B-ratio is 2.7 or 2.6y&lt;sup&gt;-1&lt;/sup&gt;, production efficiency P/A is 0.38 or 0.37. The...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Secondary production; Cyprideis torosa.
Ano: 1983
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3396

Growth and respiration of &lt;i&gt;Cyprideis torosa&lt;/i&gt; Jones 1850 (Crustacea Ostracoda)
Provedor de dados: 27
Autores: Herman, P.M.J.; Heip, C.H.R.
The ostracod &lt;i&gt;Cyprideis torosa&lt;/i&gt; Jones 1850 is a dominant species in brackish water habitats. To assess its importance, growth and respiration were measured. The shells form an increasing part of total weight as the animals grow but there is no correlation between shell weight and soft parts weight in the adults, indicating that tissue growth is a continuous process in these ostracods. Respiration was measured at 20 °C. The slope of the log-log regression of respiration on dry weight was 0.746, showing that &lt;i&gt;Cyprideis torosa&lt;/i&gt; follows the general rule for this relationship. The respiration rate per unit biomass was 0.246 nl O&lt;sub&gt;2&lt;/sub&gt; µg&lt;sup&gt;-1&lt;/sup&gt; h&lt;sup&gt;-1&lt;/sup&gt;, which is low but...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Growth; Respiration; Cyprideis torosa.
Ano: 1982
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3382

Studies of the life-history and energetics of marine and brackish-water nematodes: 1. Demography of &lt;i&gt;Monhystera disjuncta&lt;/i&gt; at different temperature and feeding conditions
Provedor de dados: 27
Autores: Vranken, G.; Herman, P.M.J.; Heip, C.H.R.
Aspects of the demography of &lt;i&gt;Monhystera disjuncta&lt;/i&gt; were investigated at different feeding conditions (monoxenic cultures with different bacterial strains, and different densities in the feeding suspension with one strain). Embryonic development time, minimum generation time, egg deposition rate and adult longevity depend on temperature, quality and quantity of food offered. Body mass at maturity is an allometric function of food density. It is shown that a previously inferred selectivity in food uptake is an artifact of culture conditions. pH buffering and addition of sterols permit culture of the species on a wide variety of bacterial strains. &lt;i&gt;M. disjuncta&lt;/i&gt; is less well adapted to take advantage of high food density...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Bioenergetics; Brackishwater environment; Cultured organisms; Feeding; Life history; Marine environment; Meiobenthos; Temperature effects; Water temperature; Monhystera disjuncta.
Ano: 1988
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3159

Estimating estuarine residence times in the Westerschelde (The Netherlands) using a box model with fixed dispersion coefficients
Provedor de dados: 27
Autores: 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

Bodemdieren langsheen estuariene gradiënten
Provedor de dados: 27
Autores: Ysebaert, T.; Herman, P.M.J.
Tipo: Info:eu-repo/semantics/article
Ano: 2001
URL: http://www.vliz.be/imisdocs/publications/280704.pdf

A model of nematode dynamics in the Westerschelde Estuary
Provedor de dados: 27
Autores: Li, J.; Vincx, M.; Herman, P.M.J.
We developed a time dynamic model to investigate the temporal dynamics of nematode community in the brackish zone of the Westerschelde Estuary. The biomass of four nematode feeding groups observed from March 1991 to February 1992 is used to calibrate the model. Using environmental data as the input, the model predicts the temporal modification and interrelation of four nematode feeding groups. Nematodes achieve a dominant position in the community because of their lower loss rate (in respiration, excretion and natural death). Predators which are deposit-feeding macrobenthos control the variations of dominant nematodes, such as omnivores and non-selective deposit feeders. Food availability causes modification only for rare nematodes such as epigrowth...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Diatoms; Ecology; Food; Light; Marine nematodes; Meiobenthos; Population dynamics; Predation; Respiration; Temperature; Nematoda [Nematodes].
Ano: 1996
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=7284

Carbon flows in the Westerschelde estuary (The Netherlands) evaluated by means of an ecosystem model (MOSES)
Provedor de dados: 27
Autores: 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&lt;sup&gt;-2&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt;) 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

One foot in the grave: zooplankton drift into the Westerschelde estuary (The Netherlands)
Provedor de dados: 27
Autores: 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

Analysis of community attributes of the benthic meiofauna of Frierfjord-Langesundfjord
Provedor de dados: 27
Autores: Heip, C.H.R.; Warwick, R.M.; Carr, M.R.; Herman, P.M.J.; Huys, R.; Smol, N.; Van Holsbeke, K.
Tipo: Info:eu-repo/semantics/article
Ano: 1988
URL: http://www.vliz.be/imisdocs/publications/221038.pdf

Secondary production of the harpacticoid copepod &lt;i&gt;Paronychocamptus nanus&lt;/i&gt; in a brackish-water habitat
Provedor de dados: 27
Autores: Herman, P.M.J.; Heip, C.H.R.
The secondary production of the harpacticoid copepod &lt;i&gt;Paronychocamptus nanus&lt;/i&gt; (Sars, 1908) in a shallow, brackish-water pond was estimated during spring and summer 1980. The population was sampled every 5 d. Production of copepodites and adults, calculated by the size-frequency method, amounts to 1.91 g m&lt;sup&gt;-2&lt;/sup&gt; dry wt over the sampling period (March-November). Egg production is 1.23 g m&lt;sup&gt;-2&lt;/sup&gt;; naupliar production is roughly 1.09 g m&lt;sup&gt;-2&lt;/sup&gt;. The production efficiency (ratio of production to production plus respiration) of copepodites and adults is 0.37; for the total population it is 0.42.&lt;i&gt;P&lt;/i&gt;:&lt;i&gt;B&lt;/i&gt; of the population is 24.45 over the sampling period, or...
Tipo: Info:eu-repo/semantics/article
Palavras-chave: Secondary production Copepoda [copepods] Paronychocamptus nanus ANE; Netherlands; Oosterschelde.
Ano: 1985
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3206

The meiobenthos of the North Sea: density, biomass trends and distribution of copepod communities
Provedor de dados: 27
Autores: 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&lt;sup&gt;-2&lt;/sup&gt;. 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