Abstract

The effect of Cu+2 on vibrionaceae associated to the bivalve Argopecten purpuratus has been studied. A. purpuratus specimens were exposed to 20 and 40 ?g Cu+2/l under culture conditions. Bacteriological analysis and quantitative determination of Cu+2 in gill, digestive gland and kidney were carried out. Later, Cu+2 tolerant vibrionaceae were isolated to determine their tolerance to several heavy metals (e.g. Cu, Cr, Zn, Cd and Hg) and resistance to antibacterials. Besides, plasmids presence in multiresistant strains were determinated. The results showed the following: i) total count of heterothrophic bacteria in treatments with and without addition of Cu+2 did not show quantitative differences; ii) a natural association was found in gill and digestive gland with Cu+2 tolerant vibrionaceae, which fluctuated between 20% and 40% of the total vibrionaceae; iii) organisms exposed to Cu+2 showed a significant increase of tolerant vibrionaceae in kidneys and digestive glands throughout the experiment; iv) the kidney showed to be an effective bioaccumulator of Cu+2; v) Cu+2 tolerant vibrionaceae showed a high tolerance to metals (Zn, Cr, Cd) and antibacterials; vi) presence of plasmids in Cu+2 tolerant vibrionaceae was confirmed.