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  • 1
    Electronic Resource
    Electronic Resource
    Comparison of rotifer culture quality with yeast plus oil and algal-based cultivation diets (1994)
    Springer
    Aquaculture international 2 (1994), S. 225-238 
    Details
    ISSN: 1573-143X
    Keywords: Rotifers ; Brachionus plicatilis ; Culture quality ; Lorica length ; Biomass ; Lipid ; Protein ; Bacterial content ; Viability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The culture quality of rotifers, Brachionus plicatilis, was compared for yeast and algal-based cultivation diets. The rotifer quality was evaluated based on factors which may affect survival and growth of marine fish larvae, including individual length and biomass, nutritional value, bacterial content, and rotifer viability. The diets used were monocultures of Tetraselmis sp., Isochrysis galbana, Pavlova lutheri, and baker's yeast plus capelin oil. Rotifers grown to early stationary phase with equal food rations exhibited equal length distribution, but the rotifer individual biomass was 10–25% higher for yeast-grown rotifers than for algal-grown rotifers. All diets gave equal protein content of individual rotifers. The lipid content was slightly higher and the ratio of protein to lipid was slightly lower with yeast plus capelin oil than with algae. The fatty acid composition of the rotifers was closely related to that of their dietary lipids and the Ω3 fatty acid content was not systematically different for the two types of diets. Use of yeast plus capelin oil resulted in considerably higher numbers of both suspended and rotifer-associated bacteria than with use of algal diets. No differences were found for the algal species involved. The viability of the rotifers in a temperature and salinity test was far better in groups fed algae than in groups fed yeast plus capelin oil. The results indicated an overall better quality of rotifers cultivated with algae than for rotifers cultivated with yeast and oil. Questions related to proteins and the microflora of rotifers should be further emphasized in future research.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00123431
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  • 2
    Electronic Resource
    Electronic Resource
    Use of swimming speed and egg ratio as predictors of the status of rotifer cultures in aquaculture (1995)
    Springer
    Hydrobiologia 313-314 (1995), S. 395-398 
    Details
    ISSN: 1573-5117
    Keywords: Aquaculture ; Brachionus plicatilis ; rotifera ; swimming speed ; egg ratio ; culture quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study evaluated the use of egg ratio (eggs rotifer−1) and swimming speed (mm min−1) as prediction criteria for production and culture quality in mass cultures of the rotifer Brachionus plicatilis. Egg ratio was determined to be a suitable predictor of rotifer growth and production in the cultures. Low egg ratios (i.e., 0–0.17 eggs rotifer−1) indicate reduced rotifer population over time (i.e., negative net population growth rates). However, at this time egg ratio dynamics are not suitably understood to predict in advance a sudden population collapse. Swimming speed of reproductive, egg-carrying females in the exponential growth phase was 40–45 mm min−1. During exponential growth swimming speed was independent of the food used. Lower swimming speeds were obtained in late stationary phase (10–25 mm min−1) when yeast was used as a food source. Both environmental factors (e.g., accumulating metabolites) and changes in nutritional state of the rotifers may have affected the swimming speed, but environmental factors appear to be the most important. We believe that swimming speed has the potential of becoming an accurate predictor of culture quality in mass cultures of rotifers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00025976
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  • 3
    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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  • 4
    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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  • 5
    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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  • 6
    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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  • 7
    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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  • 8
    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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  • 9
    Electronic Resource
    Electronic Resource
    Life history characteristics of Brachionus plicatilis (rotifera) fed different algae (1989)
    Springer
    Hydrobiologia 186-187 (1989), S. 43-50 
    Details
    ISSN: 1573-5117
    Keywords: Brachionus plicatilis ; Rotifera ; life history ; food
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A detailed study of the life history of the rotifer Brachionus plicatilis was done at 20 °C, 20 ppt salinity, and 90 mg C 1−1 food concentration. Rotifers were grown individually in culture plate wells (150 µl culture volume) and fed Isochrysis galbana Tahiti, Tetraselmis sp., Nannochloris atomus, or a l : 1 mixture (weight) of two of the algae. Observations were made every 2–8 hr and rotifers were sized and transferred to new food daily. A total of 19 different parameters were compared. Rotifers fed Isochrysis averaged 21 offspring per female, a 6.7 day reproductive period, a lifespan of 10.5 days and a mean length of 234 µm. After Isochrysis, the foods giving the highest growth, survival, and reproduction in decreasing order were Isochrysis + Nannochloris, Nannochloris, Isochrysis + Tetraselmis, Tetraselmis + Nannochloris, and Tetraselmis. Although the small volume culture system used in this study seems appropriate for studying life history of B. plicatilis, the results cannot always be directly applied to larger cultures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00048895
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