The role of ciliates within the microbial food web in the eutrophicated part of Kaštela Bay (Middle Adriatic Sea)


  • Natalia Bojanic Institute of Oceanography and Fisheries, S?etalis?te I. Mes?trovic´a
  • Mladen Šolic Institute of Oceanography and Fisheries, S?etalis?te I. Mes?trovic´a
  • Nada Krstulovic Institute of Oceanography and Fisheries, S?etalis?te I. Mes?trovic´a
  • Stefanija Šestanovic Institute of Oceanography and Fisheries, S?etalis?te I. Mes?trovic´a
  • Živana Nincevic Gladan Institute of Oceanography and Fisheries, S?etalis?te I. Mes?trovic´a
  • Ivona Marasovic Institute of Oceanography and Fisheries, S?etalis?te I. Mes?trovic´a
  • Igor Brautovic University of Dubrovnik, Institute of Marine and Coastal Research



ciliated protozoa, biotic factors, abiotic factors, microbial food web, Adriatic Sea


Interactions among phytoplankton, bacterioplankton, heterotrophic nanoflagellates (HNF), ciliated protozoa and copepod nauplii were studied in the eutrophicated part of Kas?tela Bay from May 1998 to November 1999. Special emphasis was placed on relationships between size categories of nonloricate ciliates (NLC) and other microbial food web components. Biomasses of phytoplankton and bacteria were primarily influenced by abiotic parameters. Temperature indirectly controlled variation in HNF biomass through the changes in biomass of bacteria and the smaller phytoplankton fraction. Besides HNF, bacterial biomass was affected by the NLC <103 µm3 (Cell Length <20 µm). A small NLC size category (<104 µm3, CL <40 µm) could limit the growth of HNF as they compete for bacteria and as a result of direct grazing. Nonloricate ciliates >104 µm3 (CL >40 µm) had a strong mutual correlation and they seemed to be controlling the microphytoplankton fraction. During the colder part of the year, HNF abundance was regulated by ciliate grazing. The high impact of ciliates in summer 1998 could have been influenced by the taxonomic composition of the phytoplankton community changing, as well as the higher eutrophication level in the study area. Predation by copepod nauplii on ciliates and carbon transfer to higher trophic levels appear to be of relative importance only in the period when they are most abundant. This paper outlines the dominant relationships within the microbial food web and suggests that a significant amount of bacterial production, phytoplankton and HNF biomass could be transferred to higher trophic levels through the microbial food web.


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How to Cite

Bojanic N, Šolic M, Krstulovic N, Šestanovic S, Nincevic Gladan Živana, Marasovic I, Brautovic I. The role of ciliates within the microbial food web in the eutrophicated part of Kaštela Bay (Middle Adriatic Sea). scimar [Internet]. 2006Sep.30 [cited 2021Jun.19];70(3):431-42. Available from:




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