Distribution and ecology of the tube-dweller Ampelisca ledoyeri (Amphipoda: Ampeliscidae) associated with the hydrothermal field off Panarea island (Tyrrhenian sea, Mediterranean)

The distribution and ecology of the Ampelisca ledoyeri population at the hydrothermal field off Panarea Island, Aeolian Archipelago (NE Sicily), were investigated during four cruises in June and November 2010, and June 2011, 2013. Extensive patches of emerging tubes were observed during ROV dives and subsequently grab sampled. The tubes were inhabited by the amphipod A. ledoyeri and were located close to the hydrothermal structures, with average densities ranging from 14.5 to 108.9 tubes/m2. A. ledoyeri dominated the benthic community in terms of abundance (44.4 %), monopolizing the thin layer of fine sediment covering a Fe-rich crustose substratumfrom80 to 120 m depth. The evidenced bathymetric gradient, with decreasing numbers of individuals from 80–85 m (184±266.01 individuals) to 120 m (6.95±16.08 individuals), respectively, corresponded to Ferich sediments due to geothermal lower energy and higher energy hydrothermal crusts and chimneys. The gut contents of A. ledoyeri, consisting of a fine, rusty matter similar to the seep-surface deposits, suggested that such a deposit feeder might play a key role in the hydrothermal food web, both interms of secondary production and “detrital” organic matter stored in the sediment as mucus tubes.