ISSN:
1573-5117
Keywords:
Northwestern Black Sea
;
eutrophication
;
mixotrophy
;
ciliate
;
food web
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Biomass and activities of planktonicmicroorganisms (bacteria, nanoplankton andmicroplankton) were measured in the northwestern BlackSea during summer 1995. The method based on theuptake of fluorescently labeled prey was chosen todetermine the ingestion rate of bacteria andnanoplankton by phagotrophic microorganisms. Thismethod revealed the presence of mixotrophic organismssuch as ’plastid-retaining ciliates‘ in the wholecoastal area. Mixotrophic ciliates were dominated bymicro-sized forms and maximum biomasses were recorded inthe water masses characterised by low nutrientconcentrations but high food particle concentrations. Mixotrophic nanoflagellates were absentand mixotrophic dinoflagellates were observed at onestation only. Mixotrophic ciliates were shown to ingestpreferably bacteria while mixotrophic dinoflagellateswere grazing almost exclusively on nanoflagellates.Although the biomass of mixotrophic organisms weresignificantly lower than those of aplastidic protozoa,their feeding activity contributed to 14 and 24% ofthe ingestion of bacteria and nanoplankton, respectively.This is due to the high specificingestion rate of mixotrophic micro-sized ciliates anddinoflagellates, which were two and three times higher,respectively, than the specific ingestion rate ofbacteria and nanoplankton by aplastidic protozoa. Thissuggests a significant contribution of phagotrophicmixotrophs to the microbial network of thenorthwestern Black Sea.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1003196932229
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