Epizoic diatom community on marine turtles from Omani coasts: an ultrastructural and biogeographical analysis

Benthic unicellular algae (microphytobenthos) live in different habitats: exposed beaches, lagoons, salt marshes, saline lakes, muddy and sandy sediments of intertidal and subtidal zones and hard substrates, such as macroalgae seagrasses, animals and anthropogenic substrates. The microphytobenthic community significantly contributes to primary production in shallow waters, mainly along continental shelves where it can reach values exceeding phytoplankton biomass in the overlying water column. Diatom communities are among the dominant components in the microphytobenthos and their species composition is strongly influenced by the nature of substrate and by their biogeographic distribution. On the other hand, these communities appear to be composed by a limited number of genera, belonging to different growth forms that can be considered fully adapted to the epibenthic lifestyle. Despite to their crucial ecological role in the trophic chain, the biodiversity of epibenthic diatom communities is poorly studied and greatly underestimated. Taxonomic studies at species or intraspecific level are rare since most of these species exhibit mean dimensions lower than 20 micrometers with taxonomic features often below the solving power of the light microscope. Therefore, a floristic and quantitative analysis of these communities needs scanning electron microscopy (SEM) as routinary approach. The proposed project aims to describe for the first time the biodiversity of epizoic diatom communities of Olive ridley, Green, Loggerhead and Hawksbill turtles nesting along Omani coasts and to compare it with those of Mediterranean, Atlantic and Pacific populatios of same turtle species. Moreover, given the high level of endemism that characterizes epibenthic diatom communities worldwide, we aspect to discover new species with potential biotechnological properties.