J. Mar. Biol. Ass. U.K. E2000), 80, 485^499 Printed in the United Kingdom Food sources, behaviour, and distribution of hydrothermal vent shrimps at the Mid-Atlantic Ridge A.V. Gebruk*O, E.C. Southward*, H. KennedyP and A.J. Southward* *Marine Biological Association, The Laboratory, Citadel Hill, Plymouth, PL1 2PB. OP.P. Shirshov Institute of Oceanology, Russian P Academy of Sciences, Nakhimovsky pr. 36, Moscow, 117851, Russia. School of Ocean Sciences, University of Wales^Bangor, Menai Bridge, Anglesey, LL59 5EY. Corresponding author, e-mail:
[email protected] Five species of bresilioid shrimp were investigated at seven hydrothermal sites on the Mid-Atlantic Ridge: Menez Gwen, Lucky Strike, Rainbow, Broken Spur, TAG, Snake Pit and Logatchev. Samples were prepared for analysis of stable isotopes, elemental composition and lipids. Shrimp behaviour was observed from the submersible `Alvin'and in the laboratory aboard RV `Atlantis'.The distribution and zonation of the shrimp species was recorded. Juvenile shrimp of all species arrive at the vents carrying reserves of photo- synthetic origin, built-up in the pelagic larval stages. These reserves are used while the shrimp metamorphose to the adult form and, in Rimicaris exoculata and Chorocaris chacei, while they develop epibiotic bacteria supporting structures, the modi¢ed mouthparts and the inside of the carapace. The main food of adult R. exoculata is ¢lamentous bacteria that grow on these structures. The intermediate sizes of C. chacei also feed on such bacteria, but the ¢nal stage gets some food by scavenging or predation. Mirocaris species scavenge diverse sources; they are not trophically dependent on either R.