Vibrios associated with plankton in a coastal zone of the Adriatic Sea (Italy)

From April 1996 through March 1997, culturable vibrios associated with both large (>200 mu m) and small (0.45-200 mu m) size plankton collected in the Ancona, Italy, coastal zone of the Adriatic Sea were studied. Vibrio algin olyticus was readily cultured from large size plankton from July to Septemb er and represented the only Vibrio species that could be cultured under the conditions employed in the study. Crustaceans (mainly copepods) and tunica tes (Oikopleura spp.) comprised the larger sized plankton, with copepods be ing 90% of the total plankton population in the summer months. Diatoms (Cha etoceros spp.) were also present but in lower numbers. Vibrios associated w ith smaller sized plankton comprised mainly V. alginolyticus during June-Se ptember and in March, whereas Vibrio I,vulnificus was isolated from samples collected in April, May, and March. The smaller size plankton comprised pr edominantly tintinnids, nauplii of crustaceans and exuvia of copepods. Thes e results confirm the role of zooplankton as hosts of vibrios in the enviro nment, and suggest that smaller sized plankton may serve as an important re servoir of these bacteria. (C) 1999 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.