On the biology of submarine caves with sulphur springs: Appraisal of

A.J. Southward, M.C. Kennicutt II, J. Alcalà-Herrera, M. Abbiati, L. Airoldi, F. Cinelli, C.N. Bianchi, C. Morri, E.C. Southward

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Submarine caves with sulphurous springs at Cape Palinuro, Campania, Italy, have a richer fauna than expected from the known oligotrophic nature of the cave habitat. Warm water containing sulphide issues from springs and rises above the cooler ambient seawater with a sharp thermocline/chemocline between. The warm water then escapes from the caves mixed with cooler sea- water, probably inducing an inflow of ambient sea-water. Bacterial mats, often dominated by large species of attached bacteria resembling Beggiatoa, line the upper parts of the inner caves and act as primary producers, fixing CO2by means of the autotrophic enzyme ribulosebisphosphate carboxylase. Many of the animals in the innermost parts of the caves live close to the chemocline or just below, where they would experience fall-out of bacterial organic matter, and some carry filamentous bacteria on their tubes and hard parts. Dominant members of the community include sponges, cnidarians, and tubicolous polychaetes. The inner caves form a two compartment system, with production in the upper layer of sulphurous water and consumption below. The carbon isotope ratio in the bacterial mats (range of δ13C-30.1 to-31.8‰) is a good 'marker' for tracing carbon flow, contrasting with the usual enhancement of carbon-13 in benthic photoautotrophs. Animal tissue isotope ratios confirm that bacterial carbon is entering the food chain and that this is a source of food for some cave biota. The contribution from bacteria ranges from zero to virtually 100%, depending on species and variation in local habitat. Animals living close to the bacterial mats benefit most, notably a polychaete Phyllochaetopterus, an oligochaete Thalassodrilides, a podocopid ostracod Paracypris and certain echinoderms and bivalves. The large sponges (Geodia, Petrosia) may not benefit from bacterial production.
Original languageEnglish
Pages (from-to)265 - 285
Number of pages21
JournalJournal of the Marine Biological Association of the United Kingdom
Issue number2
Publication statusPublished - May 1996
Externally publishedYes


All Science Journal Classification (ASJC) codes

  • Aquatic Science

Cite this

Southward, A. J., Kennicutt II, M. C., Alcalà-Herrera, J., Abbiati, M., Airoldi, L., Cinelli, F., ... Southward, E. C. (1996). On the biology of submarine caves with sulphur springs: Appraisal of. Journal of the Marine Biological Association of the United Kingdom, 76(2), 265 - 285.