Microbial Loop Structure along Trophic Gradients in the Adriatic Sea

  • P. Del Negro
  • G. Civitarese
  • P. Ramani
  • S. Fonda Umani


Seasonal observations (May 1995–February 1996) carried out along the whole Adriatic basin have significantly contributed to a better understanding of the distribution of bacterial and heterotrophic nanoplankton communities in different trophic areas. The average density values along the water column ranged from 1 × 105 to 1.6 × 106 cell mL−1 and from 1.2 × 102 to 1.9 × 103 cell mL−1 for bacteria and nanoheterotrophs respectively.

The relationships between bacterial and heterotrophic nanoplankton abundance changed along the trophic gradient suggesting that bacteria should be regulated more strongly by predation in eutrophic systems.


Bacterial Abundance Bacterial Density Southern Basin Heterotrophic Nanoflagellate Trophic Gradient 
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  1. Alldredge AL, Passow U, Logan B (1993) The abundance and significance of a class of large, transparent organic partides in the ocean. Deep — Sea Res 140: 1131–1140CrossRefGoogle Scholar
  2. Berninger UG, Finlay BJ, Kuuppo-Leinikki P (1991) Protozoan control of bacterial abundances in freshwater. Limnol Ocenogr 36: 139–147CrossRefGoogle Scholar
  3. Billen G, Servais P, Becquevort S (1990) Dynamics of bacterioplankton in oligotrophic and eutrophic aquatic environments: bottom-up or top-down control? Hydrobiologia 207: 37–42CrossRefGoogle Scholar
  4. Bird DE, Kalff J (1984) Empirical relationships between bacterial abundance and chlorophyll concentration in fresh and marine waters. Can J Fish Aquat Sci 41: 1015–1023CrossRefGoogle Scholar
  5. Bregant D, Allegra A, Azzaro F, Civitarese G, Crisafi E, La Ferla R, Luchetta A, Rabitti S (1992) Condizioni idrologiche nell’Adriatico Meridionale. Aprile 1990. Atti IX Congr AIOL, Nov 1990, pp 25–33Google Scholar
  6. Bregant D, Azzaro F, Civitarese G, Crisafi E, La Ferla R, Leonardi M, Luchetta A, Polimeni R, Raicich F (1994) Condizioni idrologiche nell’Adriatico Meridionale. Novembre 1991. Atti X Congr AIOL, Nov 1992, pp 37–46Google Scholar
  7. Caron DA, Lim EL, Miceli G, Waterbury JB, Valois FW (1991) Grazing and utilization of chrococcoid cyanobacteria and heterotrophic bacteria by protozoa in laboratory cultures and a coastal plankton community. Mar Ecol Prog Ser 76: 205–217CrossRefGoogle Scholar
  8. Cole JJ, Pace ML, Caraco NF, Seinhart GS (1993) Bacterial biomass and cell size distributions in lakes: more and larger cells in anoxic waters. Limnol Oceanogr 38: 1627–1632CrossRefGoogle Scholar
  9. Del Negro P, Ramani P, Martecchini E, Celio M (1995) Distribuzione annuale del picoplancton in una stazione costiera del Golfo di Trieste. Atti XI Congr AIOL, Oct 1994, pp 747–756Google Scholar
  10. Dufour PH, Torréton J-P (1996) Bottom-up and top-down control of bacterioplankton from eutrophic to oligotrophic sites in the tropical northeastern Atlantic Ocean. Deep-Sea Res 43: 1305–1320CrossRefGoogle Scholar
  11. Fenchel T (1986). Ecology of heterotrophic microflagellates. Adv Microb Ecol 9: 57–95Google Scholar
  12. Fuhrman JA (1999) Marine viruses and their biogeochemical and ecological effects. Nature 399: 541–548PubMedCrossRefGoogle Scholar
  13. Fuks D, Devescovi M, Precali R, Krstulovic N, Solic M (1991) Bacterial abundance and activity in die highly stratified estuary of die Krka River. Mar Chem 32: 333–346CrossRefGoogle Scholar
  14. Gacic M, Civiterese G, Ursella L (1999) Spatial and seasonal variability of water and biogeochemical fluxes in the Adriatic Sea. In: Malanotte-Rizzoli P, Eremeev VN (eds) The Eastern Mediterranean as a laboratory basin for assessment of contrasting ecosystems. Kluwer Acad Publ, Dordrecht, pp 335–357CrossRefGoogle Scholar
  15. Gasol JM (1994) A framework for the assessment of top-down versus bottom-up control of heterotrophic nanoflagellate abundance. Mar Ecol Prog Ser 113:291–300CrossRefGoogle Scholar
  16. Gasol JM, Vaqué D (1993) Lack of coupling between heterotrophic nanoflagellates and bacteria: a general phenomenon across aquatic systems? Limnol Oceanogr 38: 657–665CrossRefGoogle Scholar
  17. Harding LW, Degobbis D, Precali R (1999) Production and fate of phytoplankton: annual cycles and interannual variability. In: Malone TC, Malej A, Harding LW, Smodlaka N, Turner RE (eds) Ecosystems at the land-sea margin: drainage basin to coastal sea. Coast Estuar Stud Am Geophys Union, Washington DC, 55, pp 131–172CrossRefGoogle Scholar
  18. Krstulovic N, Solic M, Marasovic I (1998) Regulation of bacterial abundance along the trophic gradient in the central Adriatic. Rapp Comm Int Mer Mediterr 35: 360–361Google Scholar
  19. La Ferla R, Monticelli LS, Giacobbe MG, Crisafi E (1993) Microbial aspects of the Southern Adriatic Sea: present knowledge and fixture prospects. In: Workshop Ric Mar Mediterr 2000 Oceano. Roma, Oct 1993Google Scholar
  20. Martinussen I, Thingstad TF (1991) A simple double staining technique for simultaneous quantification of auto-and heterotrophic nano-and picoplankton. Mar Microb Food Webs 5: 5–11Google Scholar
  21. Murphy LS, Haugen EM (1985) The distribution and abundance of phototrophic ultraplankton in the North Atlantic. Limnol Oceanogr 30: 47–58CrossRefGoogle Scholar
  22. Pace ML, Cole JJ (1994) Comparative and experimental approaches to top-down and bottom-up regulation of bacteria. Microb Ecol 28: 181–193CrossRefGoogle Scholar
  23. Porter KG, Feig YS (1980) The use of DAPI to identifying and counting aquatic microflora. Limnol Oceanogr 25: 943–948CrossRefGoogle Scholar
  24. Puddu A, La Ferla R, Allegra A, Bacci C, Lopez M, Oliva F, Pierotti C (1998) Seasonal and spatial distribution of bacterial production and biomass along a salinity gradient (Northern Adriatic Sea). Hydrobiologia 369: 271–282Google Scholar
  25. Sanders RW, Caron DA, Berninger U-G (1992) Relationships between bacteria and heterotrophic nanoplankton in marine and freshwaters: an inter-ecosystem comparison. Mar Ecol Prog Ser 86: 1–14CrossRefGoogle Scholar
  26. Simon M, Cho BC, Azam F (1992) Significance of bacterial biomass in lakes and the ocean: comparison to phytoplankton biomass and biogeochemical implications. Mar Ecol Prog Ser 86: 103–110CrossRefGoogle Scholar
  27. Smodlaka N, Malone TC, Malej A, Harding LH (1999) Introduction. In: Malone TC, Malej A, Harding LW, Smodlaka N, Turner RE (eds) Ecosystems at the Land-Sea Margin: drainage basin to coastal sea. Coast Estuarine Stud Am Geophysi Union, Washington DC, 55: 1–6CrossRefGoogle Scholar
  28. Solic M, Krstulovic N (1994) Role of predation in controlling bacterial and heterotrophic nanoflagellate standing stocks in the coastal Adriatic sea: seasond patterns. Mar Ecol Prog Ser 114: 219–235CrossRefGoogle Scholar
  29. Solic M, Krstulovic N (1995) Bacterial carbon flux through the microbial loop in Kastela Bay (Adriatic Sea). Ophelia 41: 345–360Google Scholar
  30. Thingstad TF, Sackshaug E (1990) Control of phytoplankton growth in nutrient recycling ecosystems: theory and terminology Mar Ecol Prog Ser 63: 261–272CrossRefGoogle Scholar
  31. Turk V, Lipej L, Malej A (1990) Heterotrophic plankton dynamic in die stratified water-column in the Gulf of Meste. Rapp Comm Int Mer Mediterr 32: 216Google Scholar
  32. Weinbauer MG, Höfle MG (1998) Significance of vird lysis and flagellate grazing as factors controlling bacterioplankton production in a eutrophic lake. Appl Environ Microbiol 64: 431–438PubMedGoogle Scholar

Copyright information

© Springer-Verlag Italia 2001

Authors and Affiliations

  • P. Del Negro
    • 1
  • G. Civitarese
    • 2
  • P. Ramani
    • 1
  • S. Fonda Umani
    • 1
  1. 1.Laboratorio di Biologia MarinaTriesteItaly
  2. 2.Istituto Sperimentale TalassograficoCNRTriesteItaly

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