Biodiversity and ecology of Bryozoa from Iberian seamounts

Seamounts, which are geological structures that do not reach the present-day sea surface, are ubiquitous and striking features in all oceans. Contrasting with the vast surrounding abyssal plains that are covered by fine sediments and are inhabited by detritivore communities, seamounts are often characterised by diverse, epibenthic, filter-feeder assemblages that colonise the exposed rocks and coarse sediment. Although research on seamount ecosystems was intensified during the last two decades, little is known about these benthic assemblages to date. Of the c. 800 seamounts that are recorded in the North Atlantic, only very few of them can be regarded as thoroughly investigated. The geographic isolation of seamounts and their exceptional ecosystems have raised a number of different hypotheses concerning the biogeography and ecology of seamount biota. For instance, it has previously been suggested that seamounts are island habitats with highly diverse and endemic faunas, and that they act as stepping- stones in the dispersal of species across ocean basins. However, an accumulating amount of data and modern analytical techniques mostly yielded contradictory results concerning levels of endemism and biogeographic patterns of seamount biota. The Bryozoa, which comprise exclusively colonial, filter-feeding, benthic animals, are ideal model organisms to test these hypotheses. Bryozoans occur abundantly from shallow shelf to bathyal depths, and their species have a relatively restricted geographic occurrence. Despite these advantages, bryozoans have not been included in any major ecology or biogeography analysis. In this project, the bryozoan species collected during historical and recent scientific expeditions to three large geological structures off the Atlantic coasts of Iberia (Le Danois Bank, Galicia Bank and Gorringe Bank) will be revised or newly described. Based on this faunal inventory, a number of biodiversity and ecological analyses will be conducted. The species distribution on the seamounts, as well as between seamounts and the Iberian shelf, will be investigated in order to estimate the level of endemism and faunal connectivity between these sites. The seamount habitats will be characterised, and the controlling factors for bryozoan species distributions and faunal gradients be determined to test whether seamount faunas are ecologically distinct from those occurring on the continental shelf. Additionally, ecological niche modelling will be applied to the most conspicuous faunal elements to predict their occurrence in hitherto unsampled areas. The outcome of this project will significantly add to our understanding of the natural history of the Iberian seamounts in particular, and of seamount biota in general.