Updated checklist of the marine gelatinous macrofauna from the Azores

• ¹ OKEANOS Center, University of the Azores, Portugal
• ² Centre for Molecular and Environmental Biology, University of Minho, Portugal

The marine macroplankton and micronekton fauna of the Azores, which includes jellatinous creatures, have been little investigated, despite their recognized importance in trophic interactions, both as preys or predators. Probably, such lack of knowledge reflects the difficulty of sampling these fragile animals, associated with a lack of taxonomic expertise. The Azorean jellies may thus be referred as “forgotten fauna”. Jellies are characterized by the gelatinous transparent body with high water levels and low carbon content. These oceanic drifters, ranging from small to large-sized organisms or colonies, comprehend several taxonomic groups of invertebrates: cnidarians (hydromedusae, scyphomedusae and siphonophores), ctenophores and pelagic tunicates (appendicularians, doliolids, pyrosomes and salps). Some jellies are voracious predators of zooplankton (competing for food with fish) and ichthyoplankton (eggs, larval and juvenile stages of fish), affecting recruitment of commercial important species. Therefore, they may severely impact fisheries. On the other hand, many jellyfish species may represent an important component of the diet of several species with commercial interest or sensitive conservation status, such as the loggerhead sea-turtle Caretta caretta and the sunfish Mola mola, which are specialized predators of these organisms. Additionally, for example salps are efficient filter-feeders, which may consume most of primary production in short time periods, responding quickly to microalgae blooms. Some gelatinous species with stinging capability may severely affect tourism activities. We therefore intended to update the checklist of the marine gelatinous macrofauna occuring within the Azores EEZ (exclusive economic zone). We reviewed and analyzed the ocorrence of gelatinous macrofauna biodiversity in the Azores Sea, through available records in scientific literature, taxonomic collections, databases of photographs and video footages, and online digital platforms. Our updated list of jellies occurring in the Azores comprehends around 80 species (cnidarians, ctenophores and chordates), ranging from very common species as the mauve stinger (Pelagia noctiluca) and the Portuguese man-o-war (Physalia physalis), to more unusual species such as pyrosomes (Pyromoma sp.) and deep-sea medusae (Deepstaria enigmatica). To the best of our knowledge, the first report of jellies for the Azores was given by Maas (1904), who curiously registered three scyphozoan species (Atolla wyvillei, Periphylla periphylla and Aurelia aurita) not that common, presently, in the archipelago. Some important contributions to our knowledge on Azorean jellies were provided in the last half of the last century, highlighting works of Kramp (1959), Baker (1967) and Soest (1973). The most recent species checklists including pelagic jellies in the Azores reported solely a total of twenty two species (Morton et al. 1998, Costa 2010, ImagDOP 2013, SRMCT 2014). Although, our own investigations of total reports/sights indicate: 41 species of Hydrozoa (nine Antoathecata, 10 Leptothecata, nine Narcomedusae, 13 Trachymedusae), seven Scyphozoa (four Coronatae and three Semaeostomeae), 21 Siphonophora (16 Calycophorae, one Cystonectae, four Physonectae), four Ctenophora (one Nuda and three Tentaculata), two Thaliacea (one Pyrosomatida and one Salpida). While we expect much more biodiversity to be found in the archipelago, the hydrozoans and siphonophores thus seem the most specious groups of jellies in Azorean waters. This study has relevant impact in fisheries and tourism, representing an important leap forward towards the comprehension of the jelatinous faunistic diversity and associated dynamics in Azorean waters.