P.D. Munro, R.J. Henderson, A. Barbour, T.H. Birbeck-1999
Aquaculture, 170 (3-4) : 229-244 (Current Contents)
Abstract:
Exposure of the rotifer Brachionus plicatilis to ultraviolet radiation in 1 mm deep liquid layers at an energy intensity of 38 mW/cm^2 reduced the rotifer bacterial load by > 90% within 2 min. Such radiation doses had no significant effect upon rotifer viability, fatty acid composition, swimming or feeding activity. The surviving bacterial flora of irradiated rotifers was similar to that of un-irradiated rotifers and there was no evidence of major differences in sensitivity to ultraviolet radiation between different bacteria. For irradiation of large numbers of rotifers, a flow-through cell was used, operated with rotifer densities of 200/ml and a flow rate of 1.5 1/min. In two separate field trials involving groups of 34,000 turbot larvae per group, higher survival was found in groups receiving ultraviolet-irradiated rotifers in which the bacterial load was reduced by 88%. This was attributed to the slower rate of colonisation of the larval gut by bacteria, as a consequence of the lower bacterial load on the rotifers. Attempts to introduce specified bacteria into the larval turbot gut in significant numbers by colonisation of either normal or irradiated rotifers with particular bacteria were unsuccessful.
(Univ Glasgow, Div Infect & Immun, Joseph Black Bldg, Glasgow G12 8QQ, Lanark, Scotland, UK)