Oceanography and Marine Biology: an Annual Review 2003, 41, 311–354 © R.N. Gibson and R.J.A. Atkinson, Editors Taylor & Francis ECOLOGY OF WHALE FALLS AT THE DEEP-SEA FLOOR CRAIG R. SMITH1 & AMY R. BACO1,2 1Department of Oceanography, University of Hawaii at Manoa, 1000 Pope Road, Honolulu, HI, 96822, USA e-mail:
[email protected] 2present address: Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA e-mail:
[email protected] Abstract The falls of large whales (30–160t adult body weight) yield massive pulses of labile organic matter to the deep-sea floor. While scientists have long speculated on the ecological roles of such concentrated food inputs, observations have accumulated since the 1850s to suggest that deep-sea whale falls support a widespread, characteristic fauna. Interest in whale- fall ecology heightened with the discovery in 1989 of a chemoautotrophic assemblage on a whale skeleton in the northeast Pacific; related communities were soon reported from whale falls in other bathyal and abyssal Pacific and Atlantic sites, and from 30mya (million years ago) in the northeast Pacific fossil record. Recent time-series studies of natural and implanted deep- sea whale falls off California, USA indicate that bathyal carcasses pass through at least three successional stages: (1) a mobile-scavenger stage lasting months to years, during which aggregations of sleeper sharks, hagfish, rat-tails and invertebrate scavengers remove whale soft tissue at high rates (40–60kgdϪ1); (2) an enrichment opportunist stage (duration of months to years) during which organi- cally enriched sediments and exposed bones are colonised by dense assemblages (up to 40000mϪ2) of opportunistic polychaetes and crustaceans; (3) a sulphophilic (“or sulphur-loving”) stage lasting for decades, during which a large, species-rich, trophically complex assemblage lives on the skeleton as it emits sul- phide from anaerobic breakdown of bone lipids; this stage includes a chemoau- totrophic component deriving nutrition from sulphur-oxidising bacteria.