Extraordinary abundance of hydrocorals (Cnidaria, Hydrozoa, Stylasteridae) in shallow water of the Patagonian fjord region

During two scuba-diving expeditions in 2005 and 2006, stylasterids were documented and sampled from fjords and channels in the Central Patagonian Zone, Chile. At 15 of a total of 33 sampling sites we found colonies of Errina antarctica. We discuss the observed distribution patterns and the variability of colony shapes. In some regions we found E. antarctica to occur in extraordinary high densities on primary and secondary hard substratum below 10 m. In the archipelago Madre de Dios we discovered large colonies of E. antarctica covering areas of more than 10,000 m2 with coverage exceeding 80%. The dense accumulations of E. antarctica have reef-like structure and form complex habitats. At one site we observed extensive mechanical damage to the corals that may result from coral extraction by divers and/or from boat anchors. Slow growth, fragility, scarceness and the lack of knowledge on their ecology make these spectacular and unique biocenoses very susceptible for damages and require protection and further studies.