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  • 1
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    Feeding selectivity and egg production of Calanus helgolandicus in the English Channel (2000)
    In:  EPIC3Limnology and Oceanography, 45, pp. 44-54
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    Publication Date: 2019-07-16
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 2
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    Feeding, growth and reproduction in the genus Calanus (2000)
    In:  EPIC3Ices journal of marine science, 57(6), pp. 1708-1726
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    Publication Date: 2019-07-16
    Repository Name: EPIC Alfred Wegener Institut
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  • 3
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    Feeding rates and selectivity among nauplii, copepodites and adult females of Calanus finmarchicus, and Calanus helgolandicus (2002)
    In:  EPIC3Helgoland Marine Research, 56, pp. 169-176
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    Publication Date: 2019-07-16
    Repository Name: EPIC Alfred Wegener Institut
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  • 4
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    A high frequency time series at weathership M, Norwegian Sea, during the 1997 spring bloom: feeding of adult female Calanus finmarchicus. (1998)
    In:  EPIC3Marine ecology-progress series, 172, pp. 127-137
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    Publication Date: 2019-07-16
    Repository Name: EPIC Alfred Wegener Institut
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  • 5
    Electronic Resource
    Electronic Resource
    Zooplankton grazing on the coccolithophore Emiliania huxleyi and its role in inorganic carbon flux (1994)
    Springer
    Marine biology 119 (1994), S. 431-439 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Grazing and faecal pellet production by the copepods Calanus helgolandicus and Pseudocalanus elongatus, feeding on the coccolithophore Emiliania huxleyi, were measured under defined laboratory conditions, together with the chemical characteristics and sinking rates of the faecal pellets produced. Ingestion rates of both copepods were equivalent at comparable cell concentrations, the relationship between ingestion rate (I, cells copepod-1 h-1) and food concentration (C, cells ml-1), being I=0.558C for both species. P. elongatus produced a larger number of smaller faecal pellets than C. helgolandicus, but egested a larger volume of material per individual. Only between 27 and 50% of the ingested coccolith calcite was egested in the faecal pellets, and it is possible that acid digestion in the copepod gut is responsible for these considerable losses. Average sinking rates of faecal pellets containing E. huxleyi coccoliths, produced by both species, were 〉100 m d-1. The implications of the quantitative laboratory estimates for the vertical flux of inorganic carbon are considered using recently studied shelf-break and oceanic E. huxleyi blooms in the N. E. Atlantic as examples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00347540
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  • 6
    Electronic Resource
    Electronic Resource
    Detritus as food for estuarine copepods (1977)
    Springer
    Marine biology 40 (1977), S. 341-353 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A variety of detrital foods derived from marsh plants were fed to the copepods Eurycemora affinis and Scottolana canadensis. The copepods did not survive well or produce eggs when feeding on detritus with smaller amounts of microbiota, but did well when a rich and abundant microbiota was present. Ciliated protozoans appear to be particularly important in the transfer of detrital energy to copepods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00395727
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  • 7
    Electronic Resource
    Electronic Resource
    Accumulation of 14C-1-naphthalene by an oceanic and an estuarine copepod during long-term exposure to low-level concentrations (1977)
    Springer
    Marine biology 42 (1977), S. 187-195 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Accumulation of the bi-cyclic aromatic hydrocarbon 14C-1-naphthalene in adult female Calanus helgolandicus Claus and adult female Eurytemora affinis Poppe in sea water concentrations of hydrocarbon ranging from 0.2 to 992 μg/l was studied during exposure periods of up to 15 days as part of an investigation of the possible effects on marine zooplankton of persistent exposure to low levels of petroleum hydrocarbons. With both species the body levels of radioactivity increased rapidly during the first few days of the exposure period, but after exposure for 7 to 8 days to sea water containing 50 μg hydrocarbon/l an equilibrium condition was approached; in some experiments where E. affinis was exposed to 1.0 and 10 μg hydrocarbon/l for 15 days there was no further increase in body levels of radioactivity after 7 to 8 days. Using a low concentration of hydrocarbon (1 μg/l), the quantity of radioactivity accumulated after 10 days was found to be nearly fifty times greater in the smaller species, E. affinis, than in C. helgolandicus, when expressed in terms of body weight. After they had been exposed to the hydrocarbon for several days the copepods contained a considerable proportion of radioactivity that was no longer identifiable as naphthalene and was presumably present as metabolites. Radioactivity accumulated in the copepods after several days was rapidly lost after they were transferred to uncontaminated sea water: e.g. C. helgolandicus lost nearly 90% of its body level of radioactivity in 24 h. Thereafter the rate of loss was greatly reduced, and 5% of the original body level of radioactivity still remained in the copepods at the end of 11 days. Experiments on the breakdown of naphthalene added at low concentrations to sea water samples containing natural microbial populations indicated degradation rates of 0.1 to 0.2 μg/l/24 h in oceanic water, and 2.6 μg/l/24 h in inshore water samples. The results are discussed in terms of the possible transfer of hydrocarbon to a higher trophic level in areas subjected to constant low-level inputs of petroleum hydrocarbons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397743
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  • 8
    Electronic Resource
    Electronic Resource
    A microinjection technique using a pH-sensitive dye to determine the gut pH of Calanus helgolandicus (1995)
    Springer
    Marine biology 123 (1995), S. 75-79 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract By applying a microinjection technique previously used in cell biology, a pH-sensitive dye, 2′,7′-bis(2-carboxyethyl)-5,6-carboxyfluorescein) (BCECF), was injected into the gut of the copepod Calanus helgolandicus to determine pH under a range of feeding conditions. The median gut pH of the fore- and hindguts of starved individuals was 6.86 and 7.19, respectively. This was a consistently lower pH than that observed in copepods feeding on either the diatom Thalassiosira weissflogii, the dinoflagellate Prorocentrum micans, or the coccolithophorid Emiliania huxleyi (Strain 92D), all of which had a median gut pH〉7.0. In all treatments, the median pH of the foregut was more acidic than the median of the hindgut, implying that the foregut is the site of acid secretion. The results, which demonstrate pH values down to 6.11, are discussed in terms of coccolith dissolution, pigment degradation and digestive enzyme activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00350325
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  • 9
    Electronic Resource
    Electronic Resource
    ATCase activity, RNA:DNA ratio, gonad development stage, and egg production in the female copepod Calanus helgolandicus (1999)
    Springer
    Marine biology 135 (1999), S. 1-10 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Some investigators have proposed the measurement of aspartate transcarbamylase (ATCase) activity as a suitable technique for estimating zooplankton productivity. However, this technique has never been comprehensively evaluated under controlled laboratory conditions nor compared extensively with other productivity techniques in the field. This paper describes such an evaluation, using the reproduction of the calanoid copepod Calanus helgolandicus as an index of germinal growth, an important aspect of zooplankton productivity. ATCase activity and RNA:DNA ratio both increased significantly with increasing gonad maturation. In addition, ATCase activity in females responded immediately to changing food conditions, whilst changes in egg production lagged behind by ≃24 h. Shifting the ATCase data by 24 h revealed a significant and positive correlation of ATCase activity with egg production. However, in well-fed females, ATCase activity assayed at constant temperature was apparently independent of environmental temperature conditions, whilst egg production was temperature-dependent. In the field, ATCase activity was significantly correlated with egg production only in autumn and winter; when a complete seasonal cycle was considered, no correlation was found between the two measurements. These findings suggest that ATCase is involved partially in either germinal growth and/or in other biosynthetic processes of female C. helgolandicus; thus, ATCase activity does not reflect copepod egg-production with any certainty.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050595
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  • 10
    Electronic Resource
    Electronic Resource
    Simple molecular method to distinguish the identity of Calanus species (Copepoda: Calanoida) at any developmental stage (1999)
    Springer
    Marine biology 133 (1999), S. 91-96 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Diagnostic morphological characteristics of copepods of the genus Calanus are restricted largely to minor variations in secondary sex characteristics. This presents a persistent problem in the identification of individuals to species level, especially for immature stages. We have developed a simple molecular technique to distinguish between the North Atlantic Calanus species (C. helgolandicus, C. finmarchicus, C. glacialis and C. hyperboreus) at any life stage. Using the polymerase chain-reaction (PCR), the mitochodrial large subunit (16S) ribosomal RNA (rRNA) gene was amplified from individual copepods preserved in ethanol. Subsequent digestion of the amplified products with the restriction enzymes DdeI and VspI, followed by electrophoretic separation in 2% agarose (Metaphor, FMC Ltd), produced a characteristic pattern for each species. The versatility of the method is demonstrated by the unambiguous identification to species of any life stage, from egg to adult, and of individual body parts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050446
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