Marine Alliance for Science and Technology for Scotland: Annual Science Meeting 3-5 September 2014 Hidden diversity: Coral/carbonate - faunal associations Bhavani E Narayanaswamy 1 , Tom Rea 2 , Natalia Serpetti 1 and Peter Lamont 1 1 Deep-Seas Group, Scottish Association for Marine Science, Oban, Argyll, PA35 1HY Bhavani.Narayanaswamy@sams.ac.uk 2 Marine & Freshwater Research Centre, GMIT, Galway, Dublin, Ireland Area being submitted to (delete as appropriate): 1) General science session; Preferred presentation medium (delete as appropriate): (i) oral Are you a student? (Delete as appropriate): No Most deep water biological research focuses on the fauna that can be seen either living on/within the sediment or the animals living on hard substrates such as exposed bedrock/carbonates. Very little work has been undertaken on the animals that actually reside inside carbonate structures e.g. coral, as it is often not realized that these animals exist. When sampling Senghor and Ampere seamounts in the North Atlantic, coral/carbonate samples were sometimes collected as a by-product when attempting to collect soft-sediment for infaunal analysis. On several occasions when sampling the summit plateau of Ampere seamount, large pieces of coral/carbonate were snagged when using long line hooks. By contrast in the South West Indian Ocean carbonate structures and corals were actively sampled to investigate the diversity of the associated fauna living on the outside of the corals. Samples were collected using the Kiel 6000 ROV, as well as the HYBIS. In the laboratory fauna that were visibly attached to or inhabiting the branches of the carbonates and corals were removed and identified. The large coral and carbonate pieces were broken into smaller more manageable pieces then weighed individually prior to dissolution in acetic acid. The coral/carbonate was left in the acid for a set period of time before the acid being poured through a stack of 250 μm and 32 μm sieves to collect the macro- and meio- fauna. Photographs were taken of the partially dissolved material prior to being returned to the acid solution. This process continued until no coral/carbonate material remained. The results show a wide ranging number of individuals and fauna collected (even after standardization). The age of the coral/carbonate appeared to influence the number of fauna found inside it. The older the appearance of the coral the more fauna generally found. In general polychaetes, sipunculids and sponges were the most abundant fauna. The polychaetes were mostly dominated by the syllids, sabellids and polynoids. Preliminary results from Ampere seamount indicate that ~50% of the total number of individuals collected came from dissolving the coral/carbonate material, yet they only contributed to 7% of the total biomass. This is in contrast to the results of Hutchings and Weate (1978) who found that fauna collected from crushing the coral material and also from acid dissolution contributed to <27% of the total fauna collected. Acknowledgements We would like to thank all those involved in the collection of the material. The research leading to these results has received funding from two Natural Environment Research Council grants (awarded to BN) (NE/G006415/1; NE/F005563/1) and the European Community’s Seventh Framework Programme (FP7/2007-2013) under the HERMIONE project, grant agreement no. 226354 (awarded to BN). References Hutchings PA & Weate PB (1978). Comments of the technique of acid dissolution of coral rock to extract endo- cryptolithic fauna. Aust. Zool. 19(3) 315-320.