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| Registros recuperados: 107 | |
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| 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 |
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| Ano: 1996 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=8415 |
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| Heip, C.H.R.. |
| The realized and intrinsic rates of increase of several meiobenthic populations are compared. The realized rate of increase is remarkably similar among four species of copepods, which leads to the conclusion that dominance is not a function of rate of increase or parameters influencing this rate. The result is investigated in the light of Vandermeer's (1975) Beta-competition. There is also a remarkable agreement between the values of the predator <i>Protohydra leuckarti</i> and its principal prey <i>Tachidius discipes</i>. The intrinsic rates of natural increase vary more, but are a linear function of temperature in all species investigated. This is in agreement with the theory that natural selection acts against nonlinear dynamic... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Brackish water; Meiobenthos. |
| Ano: 1977 |
URL: http://www.vliz.be/imisdocs/publications/125861.pdf |
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| 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<sub>2</sub>.h<sup>-1</sup>.µg dry wt<sup>-1</sup>, but was much lower for larger species, <i>Canuella perplexa</i> T. & A. Scott 1893 (2-3 nl O<sub>2</sub>.h<sup>-1</sup>.µg<sup>1</sup>). 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 <i>Tachidius discipes</i> 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 |
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| Vranken, G.; Heip, C.H.R.. |
| The life-cycle of <i>Rhabditis marina</i> Bastian 1865 was studied at 25°C and 20 promille salinity. The following demographic parameters were computed from life-table data: the intrinsic rate of natural increase (r<sub>m</sub>) = 0.914 day; net reproductivity (R<sub>0</sub>) = 400; minimum generation time (T<sub>min</sub>) = 4.5 days; cohort generation time (T<sub>c</sub>) = 7.2 days; mean generation time (T) = 6.6 days; and the age of an adult female when a median egg is deposited (T) = 6.1 days. Several approximate equations used to estimate r<sub>m</sub> were compared with these life-table calculations. Some give erroneous estimations and should be used with extreme caution. For... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Population characteristics; Nematoda [Nematodes]; Rhabditis marina. |
| Ano: 1983 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3260 |
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| Heip, C.H.R.; Huys, R.; Alkemade, R.. |
| Knowiedge on community structure of North Sea meiofauna has greatly increased recently. A quasisynoptic picture of meiofauna densities and copepod community structure from 171 stations of the southern North Sea, sampled in April–May 1986, has been obtained during the North Sea Benthos Survey. Latitudinal patterns in meiofauna abundance and copepod weight, abundance and diversity exist in an area between 51°30'N and 58°30'N. Using TWINSPAN-classification five major groups of copepod species can be recognized which are related to sediment type, latitude and depth. The part of the meiofauna in total benthic energy flow, their role in the benthic food web and in biogeochemical cycles is discussed based on existing literature. There are still considerable gaps... |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1992 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=7245 |
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| Heip, C.H.R.; Vincx, M.; Smol, N.; Vranken, G.. |
| Nematodes are the most abundant metazoans in marine (littoral, estuarine, coastal and oceanic) sediments, extending from the high-water mark into the deepest oceanic trenches (Nicholas, 1975). All marine free-living nematodes are considered to be members of the meiobenthos; small organisms, mainly metazoans, which are separated from the larger macrobenthos either on a methodological basis (i.e. as all animals passing a 1 mm or a 0.5 mm sieve) or a taxonomic basis (i.e. particular animal groups such as Nematoda, Harpacticoida, Gastrotricha, Kinorhyncha, Tardigrada, Foraminifera etc. which consist exclusively or mainly of small species living in sediments). In most circumstances, nematodes are numerically the dominant group of the meiofauna. In fact, they... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Ecology; Systematics; Taxonomy; Nematoda [Nematodes]. |
| Ano: 1982 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3417 |
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| Heip, C.H.R.; Smol, N.; Hautekiet, W.. |
| The extraction of nematodes and harpacticoid copepods from muddy sediments or sediments containing a large amount of organic detritus can be achieved through a series of centrifugations of the material in a sacharose solution of at least 900 g/l. The number of individuals appearing in the supernatant after each centrifugation forms a geometric series, with a ratio which is dependent on the amount of material, the concentration of the saccharose solution, and the acceleration of the centrifuge. Knowledge of this ratio allows an estimation of density after only one centrifugation. More than 90 % of the animals present in the sample can be extracted after only two centrifugations. |
| Tipo: Info:eu-repo/semantics/article |
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| Ano: 1974 |
URL: http://www.vliz.be/nl/open-marien-archief?module=ref&refid=3492 |
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| Registros recuperados: 107 | |
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