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  • 11
    Electronic Resource
    Electronic Resource
    Protein and lipid content of the rotifer Brachionus plicatilis during variable growth and feeding condition (1997)
    Springer
    Hydrobiologia 358 (1997), S. 251-258 
    Details
    ISSN: 1573-5117
    Keywords: Brachionus plicatilis ; nutrition ; growth rate ; protein content ; lipid content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rotifers (Brachionus plicatilis) grown atdifferent growth rate (μ = 0.05–0.39 d−1)were analyzed for protein, lipid, fatty acids, aminoacids and free amino acids, and values are expressedin terms of individuals and dry weight. Increase ingrowth rate is equivalent with increased food rationof the individual rotifer, which responded by higheregg ratio. The protein content per individualrotifer increased by 60–80% when the growth rate increased, whereas the protein content per dryweight showed a slight, although insignificant,increase (p 〉 0.05). The lipid content perindividual was constant, whereas lipid per dryweight decreased when the growth rate increased. Theratio DHA/EPA decreased when the growth ratesincreased. The amino acids profile in percent oftotal amino acids showed low variation betweencultures maintained at different growth rates,whereas the values expressed in terms of amino acidper individual showed higher variation. The range ofvariation for free amino acids was more pronouncedthan for total amino acids.Short-term food enrichment of poorly fed rotifers(μ = 0.05 d−1) with balanced protein richdiet resulted in increased protein and lipid contentper rotifer. The protein content per dry weightshowed only minor changes whereas lipid per dryweight increased. Contrary, short term enrichmentwith a lipid rich diet resulted in increased lipidcontent per individual rotifer and per dry weight,whereas the protein content per individual remainedconstant and the protein content per dry weightshowed a slight decrease.Our experiments show that the amount of protein, wasquite variable in rotifers, and that feeding andgrowth condition were decisive factors affecting it.The range of variation was large enough to be animportant factor during first feeding of marinelarvae, and should therefore be considered infeeding larvae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003145205602
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    Paper (German National Licenses)
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  • 12
    Electronic Resource
    Electronic Resource
    Feeding kinetics of Brachionus plicatilis fed Isochrysis galbana (1989)
    Springer
    Hydrobiologia 186-187 (1989), S. 51-57 
    Details
    ISSN: 1573-5117
    Keywords: Brachionus plicatilis ; feeding kinetics ; clearance rates ; ingestion rates ; Isochrysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Clearance and ingestion rates of Brachionus plicatilis were measured using 14C-labeled Isochrysis galbana Tahiti. Experiments were conducted at 20–22 °C, 20 ppt salinity, and algal concentrations ranging from 0.13–64 mg C 1−1. Clearance rates were constant and maximal at concentrations 〈2 mg C 1−1, with maximum rates ranging from 3.4–6.9 µl ind.−1 hr−1. The ingestion rate varied with food concentration, and was described by a rectilinear model. The maximum ingestion rate varied considerably, and was dependent on the growth rate of the rotifers. Depending on the pre-conditions, B. plicatilis ingested about 0.5 to 2 times its body carbon per day at saturating food concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048896
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    Paper (German National Licenses)
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  • 13
    Electronic Resource
    Electronic Resource
    Influence of rapid changes in salinity and temperature on the mobility of the rotifer Brachionus plicatilis (1993)
    Springer
    Hydrobiologia 255-256 (1993), S. 81-86 
    Details
    ISSN: 1573-5117
    Keywords: Brachionus plicatilis ; locomotion ; temperature ; salinity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The rotifer Brachionus plicatilis can grow in a wide range of salinities and temperatures, but rapid shifts in both salinity and temperature may result in immobilized, non-swimming rotifers. The goal of this study was to examine the effect of perturbations in temperature and salinity on the swimming pattern of the rotifer. Only slight changes in mobility were observed when rotifers were exposed to changes in temperature (from 20 °C to 8–30 °C) and to an increase in salinity (from 20% to 30%). When the salinity was reduced to 15% and 5%, the proportion of mobile rotifers was reduced to 50% and 5%, respectively. The rotifers were throughout more resistant to perturbations in temperature than to those of salinity. Combined temperature and salinity perturbations compared to perturbations in each factor separately suggested a synergetic effect of temperature and salinity on the rotifers locomotion. Transfer from cultivation conditions to low salinity (5%) and high temperature (28 °C) resulted in very low percent of mobile rotifers (0–10%). However, if the temperature was reduced to 8 °C concomitant with the changes in salinity, the percent of mobile rotifers was 85%. Rotifers use a high share of their metabolic energy for locomotion, and it is therefore not surprising that perturbations in salinity and temperature may result in partial or complete immobilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00025824
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    Paper (German National Licenses)
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  • 14
    Electronic Resource
    Electronic Resource
    Dependence of temperature on loss rates of rotifers, lipids, and ω3 fatty acids in starved Brachionus plicatilis cultures (1993)
    Springer
    Hydrobiologia 255-256 (1993), S. 13-20 
    Details
    ISSN: 1573-5117
    Keywords: Brachionus plicatilis ; lipids ; ω3 fatty acids ; starvation ; temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rotifer cultures of Brachionus plicatilis (SINTEF-strain, length 250 μm) rich in ω3 fatty acids were starved for 〉 5 days at variable temperature (0–18 °C). The net specific loss rate of rotifer numbers were 0.04 day−1 (range 0–0.08 day−1) at 5–18 °C, but reached values up to 0.25 day−1 at 0–3 °C. The loss rate was independent on culture density (range 40–1000 ind ml−1), but was to some extent dependent on the initial physiological state of the rotifers (i.e., egg ratio). The loss rate of lipids was 0.02–0.05 day−1 below 10 °C, where the potential growth rate of the rotifer is low (0–0.09 day−1). The loss rate of lipids increased rapidly for higher temperatures where the rotifer can maintain positive growth, and reached 0.19 day−1 at 18 °C. The Q10 for the lipid loss rate versus temperature was higher than the Q10 for respiration found in other strains. This may suggest that other processes than respiration were involved in lipid catabolism. The content of ω3 fatty acids became reduced somewhat faster than the lipids (i.e. in particular 22:6 ω3), but the fatty acid per cent distribution remained remarkably unaffected by the temperature during starvation. The results showed that rotifer cultures could be starved for up to 4 days at 5–8 °C without essential quantitative losses of lipids, ω3 fatty acids, and rotifers. The rotifers exhausted their endogenous lipids through reproduction (anabolism) and respiration (including enhanced locomotion) at higher temperatures. At lower temperatures, the mortality rate became very high.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00025815
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    Paper (German National Licenses)
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  • 15
    Electronic Resource
    Electronic Resource
    Kinetics of n-3 fatty acids in Brachionus plicatilis and changes in the food supply (1989)
    Springer
    Hydrobiologia 186-187 (1989), S. 409-413 
    Details
    ISSN: 1573-5117
    Keywords: Brachionus plicatilis ; live feed ; enrichment ; n-3 fatty acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Moderately starved rotifers exhibited a two-phased increase in n-3 fatty acids when they were fed a diet rich in these fatty acids. The first 20–30 min of enrichment, the increase in n-3 fatty acids was primarily due to increased gut content. The subsequent slow increase was due to an incorporation of n-3 fatty acids into rotifers tissues. Saturation was achieved before 24 h of exposure and the saturation level was independent of the initial content of n-3 fatty acids in the rotifers. Starvation and limited feeding of the enriched rotifers for additional 4–8 h at 10–20 °C did not affect the accumulated fatty acids significantly. This was found for rotifers with high and low initial content of n-3 fatty acids. The n-3 fatty acids were assimilated with high efficiency from the feed and were not metabolized faster than other groups of fatty acids. Enriched rotifers retained their nutritional value for a sufficient period after enrichment to serve well as live feed for marine fish larvae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048939
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    Paper (German National Licenses)
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  • 16
    Electronic Resource
    Electronic Resource
    Particle size dependent feeding by the rotifer Brachionus plicatilis (1993)
    Springer
    Hydrobiologia 255-256 (1993), S. 261-267 
    Details
    ISSN: 1573-5117
    Keywords: Brachionus plicatilis ; grazing ; selection ; bacteria ; microbial loop
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Size selective feeding by Brachionus plicatilis was investigated with algae and bacteria (0.3–3.5 µm) and mono-disperse latex beads (0.3–3.0 µm) in short term feeding experiments. B. plicatilis demonstrated maximum clearance rate of particles with diameter ≥2µm, but particles with diameter down to 0.3 µm were also ingested. The clearance rate of bacteria was 15–55% of that obtained for optimal sized particles (≥2 µm), and was related to particle size. The relative reduction in retention of particles with diameter 〈 2 µm was more pronounced for latex beads than for natural food particles, suggesting other mechanisms than size to be important for the particle retention by the rotifer. This is emphasized by the fact that the clearance rates were much lower for latex beads than for natural food particles of comparable size. Efficient retention of bacteria was observed for rotifers in poor physiological condition, i.e. rotifers with low maximum clearance rate. This may reflect a strategy to optimize energy utilization by reducing locomotion costs and increasing energy intake. The results indicate that B. plicatilis has a low to medium ability to feed on bacteria. In natural ecosystems, its importance as a bacterial grazer is of limited importance. At high population densities, such as in live feed cultures, the rotifer may, however, efficiently remove bacteria from the culture.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00025847
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    Paper (German National Licenses)
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  • 17
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    Feeding selectivity of Calanus finmarchicus in the Trondheimsfjord (2014)
    Elsevier
    In:  Journal of Sea Research, 85 . pp. 292-299.
    Details
    Publication Date: 2017-07-19
    Description: Highlights: • Incubation experiments showed an omnivore feeding of Calanus finmarchicus. • Ciliates were positively selected by C. finmarchicus at varying food concentrations. • The degree of omnivory depended on the proportion of ciliates available. Abstract: The feeding selectivity of Calanus finmarchicus was studied by carrying out three incubation experiments; two experiments with natural seawater sampled during spring bloom (Exp. 1) and post-bloom conditions (Exp. 2) and a third experiment with cultured dinoflagellates and ciliates (Exp. 3). In the first two experiments a gradient in ciliate concentration was created to investigate the potential for prey density dependent selective feeding of C. finmarchicus. Results of microplankton counts indicated C. finmarchicus to be omnivorous. Diatoms contributed chiefly to the diet during spring bloom conditions. Despite the high microphytoplankton biomass during the spring bloom (Exp. 1), ciliates were selected positively by C. finmarchicus when the ciliate biomass exceeded 6.5 μg C L− 1. A selection in favor of large conic ciliates such as Laboea sp. and Strombidium conicum was indicated by positive selectivity indices. Ciliates were throughout positively selected by C. finmarchicus during Exp. 2, and selectivity indices indicated a negative selection of diatoms. The results from Exp. 3 showed that C. finmarchicus has the ability to switch from dinoflagellates to ciliates as sole food source, even if the dinoflagellate was offered in surplus. This suggests that other factors, such as nutrition may be of significance for the feeding selectivity of C. finmarchicus.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.seares.2013.05.012
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 18
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    Responses of biological and chemical components in North East Atlantic coastal water to experimental nitrogen and phosphorus addition – A full scale ecosystem study and its relevance for management (2014)
    Elsevier
    In:  Science of the Total Environment, 473-474 . pp. 262-274.
    Details
    Publication Date: 2020-06-26
    Description: Highlights: • A full-scale 5 year experimental study of ecosystem responses to increased nutrients. • Concentrations of DIN and DIP did not respond positively to increased nutrient input. • Concentrations of PON and POP and phytoplankton biomass responded positively. • PON is suggested as credible indicator for chemical and ecological state. • A general scientific concept for managing nutrient input to coastal waters is presented. Abstract: The objective of this study was to quantify chemical and biological responses to an experimentally increased nutrient input to an open coastal planktonic ecosystem and to contribute to a scientific concept and credible indicators for managing nutrient supply to coastal waters. Data were derived in a 5 year fertilisation experiment of a tidal driven coastal lagoon at the outer coast off Central Norway (63°36’ N, 9°33’ E), with a surface area of 275.000 m2, volume of 5.5 mill m3, mean depth of 22 m and a water exchange rate of 0.19 day- 1. The lagoon was fertilised in the summer season 1998 and 1999, while summer seasons 1996-97 and 2000 and inflowing water were used as unfertilised references. Most measured chemical and biological variables showed linear responses with an increasing loading rate of inorganic N and P (LN and LP, respectively). PON, POP and POC (〈 200 μm) responded significantly (P 〈 0.05) as did chlorophyll a and phytoplankton C. DIN and DIP remained, however, constant and independent of LN and LP, respectively (P 〉 0.05) as did heterotrophic biomass (P 〉 0.05). We evaluate the response variables assuming a stepwise incorporation process of nutrients in the planktonic ecosystem and how that will interact with biological response times and water dilution rates. We suggest that PON is a credible indicator of both chemical and ecological states of the planktonic ecosystem and that natural background and upper critical concentrations are 46 and 88 mg PON m- 3, respectively. The study was supported by data from mesocosms. We discuss the scientific relevance of our suggestions, how results can be extrapolated to a broader geographical scale, and we propose a science-based concept for the management of nutrient emission to open coastal waters.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.scitotenv.2013.12.028
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 19
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    Response of the microbial food web to gradients of organic matter and grazing pressure and multi-stressor effect in incubation experiments in three different marine ecosystems: Patagonia, Arctic and Mediterranean (2020)
    PANGAEA
    Details
    Publication Date: 2024-04-27
    Description: The data-sets comes from three locations representative of three different marine ecosystems: Fjord (Chilean Patagonia), Ny-Ålesund (Arctic) and Mediterranean (Crete). It contains chemical and biological data collected in three mesocosm and four microcosm experiments conducted in the spring - summer period, in which the physico-chemical (pH, Carbon) and biological (grazing) conditions were altered to represent potential future climate change scenarios. The data-sets contains measurements in: carbonate chemistry, macro- and micro-nutrients concentrations, primary production, phytoplankton taxonomy, virus abundance, bacterial production, bacterial abundance, Zoo- and microzoo-plankton abundance, grazing rates for different taxonomic groups.
    Keywords: Arctic; Climate change; climatic; fjords; Marine ecosystems; Mediterranean; Microbial Food Web; multi-stressors; non-climatic; OCEAN-CERTAIN; Ocean Food-web Patrol – Climate Effects: Reducing Targeted Uncertainties with an Interactive Network
    Type: Dataset
    Format: application/zip, 7 datasets
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    DATA PANGAEA
  • 20
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    Response of the microbial food web to gradients of organic matter and grazing pressure effect in incubation experiments in the Arctic: Mesocosm (2020)
    PANGAEA
    Details
    Publication Date: 2024-04-27
    Keywords: 19-Hexanoyloxyfucoxanthin; Abundance; Abundance per volume; Alloxanthin; Ammonium; Arctic; Arctic: Ny-Alesund - (west coast of Spitsbergen); Bacterial production; beta-Carotene; Carbon, organic, dissolved; Carbon, organic, particulate; Carbon, organic, total; Chlorophyll a; Chlorophyll b; Chlorophyll c2; Chlorophyll c3; Chlorophyllide a; Climate change; climatic; Copepoda, biomass as carbon; DATE/TIME; Day of experiment; Diadinoxanthin; Diatoxanthin; fjords; Fucoxanthin; Gross primary production of oxygen; Iron; Iron, dissolved; Iron, particulate; Lutein; Marine ecosystems; Mediterranean; MESO; Mesocosm experiment; Microbial Food Web; Monovinyl chlorophyll a; multi-stressors; Net community production of oxygen; Nitrate; Nitrogen, organic, particulate; Nitrogen, total; Nitrogen/Carbon ratio; non-climatic; Number; OC_Arctic_Mesocosm; OCEAN-CERTAIN; Ocean Food-web Patrol – Climate Effects: Reducing Targeted Uncertainties with an Interactive Network; Peridinin; pH; Pheophorbide b; Pheophytin a; Phosphate; Phosphorus, particulate; Primary production of carbon; Ratio; Respiration rate, oxygen; Silicate; Time in hours; Treatment; Violaxanthin; Viral abundance; Zeaxanthin
    Type: Dataset
    Format: text/tab-separated-values, 5638 data points
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    DATA PANGAEA
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