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  • 1
    Book
    Book
    Berlin : Springer
    Keywords: Differentialgleichung ; Numerisches Verfahren ; R
    Type of Medium: Book
    Pages: XVI, 248 S. , Ill., graph. Darst. , 24 cm
    ISBN: 3642280692 , 9783642280696
    Series Statement: Use R!
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    Language: English
    Note: Literaturangaben. - Zusätzliches Online-Angebot unter extras.springer.com
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  • 2
    Keywords: Ecology Mathematical models ; R (Computer program language) ; Computersimulation ; R ; Ökologie ; Modellierung
    Description / Table of Contents: Many texts on ecological models jump to describing either particular relations or computational results, without treating in detail the conceptual and mathematical basis of many steps in modelling: why set up models, what are basic conceptual models, how do conservation laws come in, how are models solved, what are steady states. This book is intended to bridge this gap. It is intended as an introductory text for graduate and post-graduate students, but also as a help for experienced ecologists who want to make more of their data by modelling. It contains many examples, all worked out in the open-source package R, providing the reader the opportunity to practice all methods and get hands-on experience. Audience: This book will be of interest to advanced undergraduate and graduate students in ecology, biology, geology, bio-engineering, and to some extent students from physics and chemistry
    Type of Medium: Book
    Pages: XV, 372 S. , graph. Darst. , 235 mm x 155 mm
    ISBN: 9781402086236
    DDC: 577.015118
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    Language: English
    Note: Literaturverz. S. 361 - 365
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  • 3
    ISSN: 1573-5117
    Keywords: secondary production ; copepod ; estuary ; Westerschelde
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The zooplankton community of the brackish part of the Westerschelde estuary (November 1989–October 1990) was dominated by two calanoid copepods, Eurytemora affinis and Acartia tonsa. Eurytemora was present during a longer period of the year and was much more important in terms of total abundances and biomasses than Acartia. The secondary production of these species was estimated by means of the growth rate method, using weight-specific growth rates obtained from laboratory cultures (Eurytemora) or from the literature (Acartia). Due to the substantially higher growth rates of Acartia compared to Eurytemora, total yearly productions of both communities were comparable, notwithstanding the large discrepancies in biomass. They amounted to about 5 and 6 g C m−2 y−1 by Acartia and Eurytemora respectively. The food needed to realise this production was estimated to be about 14 and 17 g C m−2 y−1 by Acartia and Eurytemora respectively. Provided that the copepods are able to selectively ingest the phytoplankton, in situ net production provides sufficient carbon for zooplankton demands for a short period of the year only. As phytoplankton standing stock is very low and net phytoplankton productivity is negative from late fall to early spring, nutritional demands of the copepods have to be fulfilled by other than algal food at least during this period of the year. Although the copepods in the brackish part can have an important impact on some food items, their contribution to total carbon fluxes in the brackish zone is negligible: each year some 6% of all consumed carbon in the brackish part of the estuary passes through the copepod food web.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-5117
    Keywords: carbon ; budget ; autotrophy ; heterotrophy ; Westerschelde ; estuary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 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−2 yr−1) 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 half of the Westerschelde. On the scale of the entire estuary, benthic primary production amounts to about 60% of pelagic primary production. Water-column nitrification, which is very important in the nitrogen cycle, is most pronounced near the turbidity zone where it accounts for the major autotrophic fixation of carbon (up to 27 g C m−2 yr−1). Viewed on the scale of the total estuary, however, the process is not very important. Less than 20% of total organic carbon input to the estuary is primary produced, the remainder is imported from waste discharges and from the river. The degree of heterotrophy of the Westerschelde estuary proved to be one of the highest yet reported. On average 380 g carbon per square metre is net lost per year (range 200–1200 gC m−2 yr−1). The yearly community respiration (bacterial mineralization, respiration of higher trophic levels and sedimentation) is 4 to 35 times (estuarine mean of 6) higher than the net production. This degree of heterotrophy is highest near the turbidity maximum and generally decreases from the freshwater to the seaward boundary. About 75% of all carbon losses can be ascribed to pelagic heterotrophic processes; the sediment is only locally important. Mineralisation rates are highest in the turbidity region, but as only a fraction of total carbon resides here, less than 20% of all organic carbon is lost in this part of the estuary. This result is in contradiction with a previous budget of the estuary, based on data of the early seventies, where more than 80% of all carbon was estimated to be lost in the turbidity zone. Part of this discrepancy is probably caused by changes that have occurred in the estuary since that time. Due to the high heterotrophic activity, nearly all imported and in situ produced carbon is lost in the estuary itself and the Westerschelde is an insignificant source of organic matter to the coastal zone. The model estuary acts as a trap for reactive organic matter, both from the land, from the sea or in situ produced. Internal cycling, mainly in the water column, results in the removal of most of the carbon while the more refractory part is exported to the sea.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-5117
    Keywords: Nematoda ; Comesomatidae ; deep sea ; Indian Ocean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Twelve new and known species of the genera Sabatieria,Cervonema, Paramesonchium, Hopperia and Dorylaimopsis and one new genus, Kenyanema aredescribed from the Indian Ocean and S. pisinna Vitiello,1970 from the Mediterranean Sea. Sabatieria lucia sp. n.is characterised by short but distinct inner and setiformouter labial sensilla and long (4–5 µm or 30–33% hd)cephalic sensilla; S. conicauda Vitiello, 1970, ischaracterised by tiny inner and outer labial sensilla andsetiform cephalic ones and short and thick cylindrical tail;Sabatieria pisinna is characterised by short innerand outer labial sensilla, setiform (3µm long) cephalicsensilla, multispiral amphids with 3.25–3.5 turns and a tailwhich is conical in the anterior 2/3 and posterior 1/3cylindrical; Cervonema tenuicauda Schuurmans Stekhoven,1950, is characterised by anterior sensilla in twocircles which are equal in length (3µm long), multispiralamphids with 3–4 turns and located at 1.5 times hd from theanterior end, simple spicules one abd long and 6–7 fineprecloacal supplements; Cervonema minutus sp. n.characterised by an extremely attenuated anterior end,spiral amphids with 4–5 turns (80–90% cbd) and short,simple spicules (0.8 abd long); Cervonema gourbaulti sp.n. characterised by long (4–5 µm) labialand cephalic sensilla, spiral amphids with 5–6 turns(73–88% cbd) and an elongate crenate terminal pharyngealbulb; Paramesonchium mombasi sp. n. characterised bylong labial (5 µm) and cephalic (21 µm) sensilla thatare close together and wide amphids (80–90% cbd); Kenyanema monorchis gen. et sp. n. characterised bya head region narrower than the rest of the body, fourcephalic sensilla (3 µm long) and spiral amphids with1.5–2 turns; Hopperia indiana sp. n. characterised byshort conical anterior sensilla, arcuatespicules that have a ‘velum’ and a gubernaculum with a longand sharp pointed apophysis; Dorylaimopsis coomansi sp.n. characterised by long (8–10µm) cephalic setae,cuticular punctation with lateral differention of irregularlyarranged dots at the pharyngeal region and 1–3longitudinal rows of dots posterior of the pharynx; spiculeswith a unique shape; Dorylaimopsis gerardi sp. n.characterised by short setiform labial and long (6–7 µm)cephalic sensilla, punctated cuticle with lateraldifferentiation of irregularly arranged dots at firstthen three or four irregularly arranged longitudinal rows atthe pharyngeal and tail regions and two regularly arrangedlongitudinal rows of dots on the rest of the body, aconico-cylindrical tail with a distinctly swollen tip;Dorylaimopsis variabilis sp. n. is characterised byshort labial and setiform cephalic sensilla (33–58% hd),multispiral amphids with three turns, cuticular punctationswith lateral differentiation of three longitudinalrows at the pharyngeal and tail regions and two longitudinalrows on the rest of the body, spicules that are thin andslightly arcuate. The position of S. pisinna accordingto the grouping of Platt, 1985 of Sabatieriaspp. is also discussed. Kenyanema monorchis representsthe first monorchic species in the family.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-5117
    Keywords: Meiobenthos ; nematoda ; estuary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 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 nematode community analysis, we also included data from the Tamar which were obtained from the literature (Warwick & Gee, 1984). This resulted in the enumeration of 220 species, belonging to 102 genera, each with a characteristic distribution along the salinity, sedimentary and latitudinal gradients. Using the multivariate technique CANOCO, a zonation along these different physicochemical determinants was observed as well although salinity and sediment characteristic (scale of hundreds of meters to kilometers) proved to be more important in explaining community structure than latitudinal differences (scale of hundreds of kilometers). Nematode diversity was nearly entirely determined on the genus level and was positively related to salinity. Deviations from this general trend in the Gironde and the Tamar were attributed to sedimentary characteristics or to low macrobenthic predation. The presence of a typical opportunistic colonizing nematode species Pareurodiplogaster pararmatus in the low-salinity region of the Gironde could indicate (organic?) pollution or disturbance of the intertidal mud-flats.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-5117
    Keywords: residence times ; Westerschelde ; estuary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 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 freshwater flow, which is observed in certain studies, could (partly) reflect the deviation from steady state conditions which are required assumptions to calculate these dispersive coefficients directly from salinity profiles.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-5117
    Keywords: Nitrogen ; budget ; nitrification ; denitrification ; Westerschelde ; estuary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 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 space. Also, model output of biochemical oxygen demand and total organic carbon falls within observed ranges. By far the most pervasive process in the nitrogen cycle of the estuary is nitrification which mainly takes place in the water column of the upper estuarine part. On average about three times as much nitrate is leaving the estuary at the sea side compared to what enters from the river and from waste discharges. Ammonium on the other hand is consumed much faster (nitrification) than it is regenerated and only about one third of the total import leaves the estuary at the sea side. The budget for detrital nitrogen reveals import from the river, from wastes and from the sea. Phytoplankton uptake of inorganic nitrogen is negligible in the model. About 21% of total nitrogen, 33% of inorganic nitrogen, is removed from the estuary (mainly to the atmosphere through denitrification) and the load of nitrogen net exported to the sea amounts to about 51 000 tonnes per year. Total denitrification in our model is lower than what was estimated in the literature from the late seventies, where a nitrogen removal up to 40–50% of the total inorganic load was reported. Part of the differences could be methodological, but inspection of the nutrient profiles that led to these conclusions show them to be different to the ones used in our study. The oxygen deficient zone has moved upstream since the late seventies, entrailing the zone of denitrification into the riverine part of the Schelde. The nitrification process now starts immediately upon entering the estuary.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-5117
    Keywords: marine ; nematodes ; Tricoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Eight new species of the genus Tricoma are described from the Mediterranean: Tricoma (Tricoma) apophysis sp.n., Tricoma (T.) latispicula sp.n., Tricoma (T.) corsicana sp.n., Tricoma (T.) pygmaea sp.n., Tricoma (T.) vincxae sp.n., Tricoma (T.) duopapillata sp.n., Tricoma (T.) setosa sp.n. and Tricoma (Quadricoma) tripapillata sp.n.. All are noteworthy for being small.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 185 (1989), S. 127-143 
    ISSN: 1573-5117
    Keywords: Desmoscolex from a Mediterranean deep-sea transect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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