Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Nutritional characteristics of a mixotrophic nanoflagellate,Ochromonas sp. (1989)
    Springer
    Microbial ecology 17 (1989), S. 251-262 
    Details
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Autotrophic and heterotrophic growth characteristics of a nano-flagellate were investigated. The flagellate,Ochromonas sp., was isolated from the northern Baltic Sea. Autotrophic growth was poor. Axenically pregrown flagellates did not increase significantly in cell number during incubation in different inorganic media. The number of flagellates remained constant 3–5 weeks in cultures kept in the light (100μmol m−2 sec−1), whereas in the dark, a high mortality rate was found. Uptake of inorganic14C into an acid-stable fraction indicated thatOchromonas had a functional photosynthetic apparatus. Heterotrophic growth in both liquid medium and medium containing bacteria was rapid. The maximum growth rate corresponded to a generation time of 5.3 hours. Light had no effect on heterotrophic growth. Cells pregrown onEscherichia coli minicells survived without additional bacteria as food when kept in the light, but rapid death occurred in darkness. In conclusion, heterotrophy is the major mechanism to support growth in this species ofOchromonas, but under poor environmental conditions photoautotrophy might be a strategy for survival rather than growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02012838
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Development of ice biota in a temperate sea area (Gulf of Bothnia) (1994)
    Springer
    Polar biology 14 (1994), S. 531-537 
    Details
    ISSN: 1432-2056
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A study of sea ice biota was carried out in the Gulf of Bothnia (northern Baltic Sea) during the winter of 1989–1990. Samples (ice cores) were taken at a coastal station at regular time intervals during the ice season. Chlorophyll a concentration, algal species distribution, bacterial numbers, and primary and bacterial production were measured. Colonization of the ice began in January when daylight was low. As the available light increased, the algae started to grow exponentially. The vertical chlorophyll a distribution changed and algal species composition and biomass changed during the season. During the initial and middle phase of colonization, ice-specific diatoms, Nitzschia frigida and Navicula pelagica, dominated the algal biomass. Nutrients (PO4 3− and NO3j) were found to be depleted during the time of algal exponential growth. The maximum algal biomass exceeded 800 μg C 1−1. The primary production supplied food for heterotrophic organisms. The presence of heterotrophic organisms of different trophic levels (bacteria, flagellates, ciliates and rotifers) indicated an active microbial food web.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00238222
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Potential importance of protozoan grazing on the accumulation of polychlorinated biphenyls (PCBs) in the pelagic food web (1997)
    Springer
    Hydrobiologia 357 (1997), S. 53-62 
    Details
    ISSN: 1573-5117
    Keywords: bacterivory ; bioaccumulation ; microbial food web ; PCBs ; polychlorinated biphenyls ; protozoa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Experiments were conducted to study the distribution of three selectedpolychlorinated biphenyl (PCB) congeners within the microbial food web attwo different nutrient levels; control and nutrient enriched. The objectivewas to quantify the uptake of PCBs through grazing by protozoa. The14C-PCBs tested were 4-chlorobiphenyl (IUPAC # 3),2,2′,5,5′-tetrachlorobiphenyl (IUPAC # 52), and2,2′,4,4′,5,5′-hexachlorobiphenyl (IUPAC # 153). EachPCB was incubated in triplicate seawater samples at 20 idref;Cover one week. Daily, samples were separated into four fractions; 〈0.2µm (dissolved), 0.2-2 µm (bacteria), 2-10 µm(flagellate), and 〉 10 µm (microplankton; phytoplankton andprotozoa) by selective filtration. Of the PCB fraction that initiallyadsorbed to particles, 60–100% was associated to the bacterialfraction and 0–5% to the microplankton fraction. The totaluptake was highest in the nutrient enriched samples, but when normalized tothe carbon biomass the concentration was lower or equal to the control inall particle fractions. The recovery of the PCBs in the particulatefractions depended on the degree of chlorination, as the highest values wereobserved for the 2,2′,4,4′,5,5′-hexachlorobiphenyl and thelowest for the 4-chlorobiphenyl. The concentrations in the bacterial andflagellate fractions decreased over the first 48–96 hours whilst theconcentration increased in the highest trophic level (〉10 µmfraction). Approximately 75% of the increase in concentration of the2,2′,4,4′,5,5′-hexachlorobiphenyl in the 〉 10 µmfraction was estimated to be the result of bacterivory. Our results indicatethe microbial food web can contribute to a rapid uptake of higherchlorinated PCBs, particularly in oligotrophic ecosystems where thebacterial biomass dominates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003122500557
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...