Europa is one of the Eparses Islands, French islands scattered in the Mozambique Channel. They are isolated islands of coral origin, without permanent human population. This situation makes them good candidates to evaluate the evolution of biodiversity without direct anthropogenic influences. Knowledge is still scarce because their accessibility is limited. With the idea of classifying them as Marine Protected Areas, a management plan is required based on the coral reef communities. Among several aims, the program BioReCIE (Biodiversity, Resources and Conservation of Eparses Islands) was to complete the inventories of several marine groups, including the echinoderms, which had never been assessed before. In November 2011, a multidisciplinary team explored the reef slopes of the island by scuba diving down to 20 meters (10 sites), and the reef flats at low tide (14 sites, including the lagoon surrounded by mangrove), collecting and taking photos of the organisms which have been preserved in 95% ethanol and identified. The total species richness for echinoderms was 39 including 4 Crinoidea, 8 Echinoidea, 5 Asteroidea, with Aquilonastra chantalae a new species, 13 Ophiuroidea and 9 Holothuroidea. Twenty three species were collected on the slopes and 21 on the reef flats. Given the limited number of sites studied, the occurrence of the different species in each class is presented as frequent, infrequent or rare. The semi quantitative measure of abundance identified populations with high densities, as Stichopus chloronotus, Ophiocoma scolopendrina and Echinometra mathaei on the reef flats. Several species were only collected as juveniles. On the slopes Echinostrephus molaris, Ophiothela danae and diadematids were frequent, but with lower densities. On the whole the echinoderm fauna is not very diverse, nor abundant, except on the reef flats; the presence of holothurians near the lagoon entrance, in a mangrove habitat is notable. |
