Chapter 1 MEDITERRANEAN MARINE CAVES:

oceanography, climate change, reefs, marine science, marine conservation, marine researc

Esponjas como “hoteles vivientes” en cuevas submarinas del Mediterráneo

Although sponges constitute the dominant sessile organisms in marine caves, their functional role as ecosystem engineers has received little attention in this habitat type. In this study the associated macrofauna of the massive/tubular ecosystem-engineering sponges Agelas oroides and Aplysina aerophoba was studied across distinct ecological zones of two eastern Mediterranean caves. Our results revealed that the examined sponges supported a considerable associated macrofauna. A total of 86 associated taxa were found, including species reported for the first time as sponge symbionts and typical cave dwellers. Crustaceans predominated in terms of abundance but polychaetes showed the highest number of taxa. A clear differentiation was observed in the structure of the associated assemblage between the two sponges, attributed not only to the sponge species but also to differences in the surrounding environment. Density, diversity and the trophic structure of the sponge-associated macrofauna did not vary significantly along the horizontal axis of the surveyed caves. These findings suggest that sponges form a quite stable habitat, maintaining their functional role as ecosystem engineers across the studied marine caves and increasing habitat complexity in the impoverished inner dark cave sectors.A pesar de que las esponjas constituyen el grupo sésil dominante en cuevas submarinas, su papel como ingenieros del ecosistema dentro de estos ambientes ha recibido muy poca atención. En el presente trabajo, se ha estudiado la macrofauna asociada a las especies Agelas oroides y Aplysina aerophoba (ambas con una morfología masiva-tubular y consideradas como especies ingenieras del ecosistema) a lo largo de diferentes ambientes situados en dos cuevas marinas del Mediterráneo oriental. Nuestros resultados ponen de manifiesto que las dos especies de esponjas consideradas albergan una abundante fauna asociada. Se encontró un total de 86 taxones diferentes, muchos de los cuales son citados por primera vez como simbiontes de esponjas y habitantes de cuevas submarinas. Aunque los crustáceos fueron el grupo dominante en términos de abundancia, fueron los poliquetos los que presentaron la mayor riqueza taxonómica. Las comunidades asociadas a una y otra esponja presentaron claras diferencias, lo cual se atribuye no solo a diferencias relacionadas con las especies hospedadoras sino también al ambiente circundante. La densidad, diversidad y estructura trófica de la macrofauna asociada a las esponjas no varió significativamente a lo largo del eje horizontal de las cuevas muestreadas. Estos resultados sugieren que las esponjas forman un hábitat bastante estable, manteniendo su papel funcional como ingenieros del ecosistema a lo largo de las cuevas submarinas y, por tanto, incrementando la complejidad del hábitat en los sectores más internos, empobrecidos y oscuros de las cuevas

Mysida and Lophogastrida of Greece: a preliminary checklist

Abstract Backgroun

Comparing sessile benthos on shallow artificial versus natural hard substrates in the Eastern Mediterranean Sea

Artificial structures cover a considerable part of the Mediterranean coasts. In the Aegean Sea, most studies related to artificial structures have focused in vagile fauna on harbors and marinas but little attention has been given to the sessile biota on coastal defense structures. The aim of this work was to describe for the first time the shallow sublittoral sessile benthos on coastal defense structures in Crete (Eastern Mediterranean Sea) in order to identify potential differences in comparison to natural rocky substrates, adopting both a taxonomic and functional (i.e. macroalgal structural complexity) approach. Three shallow (1-3 m) localities were studied in the north coast and three in the south coast of the island (six localities in total). At each locality, two types of hard substrate were selected: an artificial coastal defense structure (rip-rap) and the nearest natural rocky substrates. The percent cover of sessile taxa was calculated using random points counts over photoquadrats (20 x 20 cm). The structure of the assemblage differed between artificial and natural habitats. Values of Shannon-Wiener’s diversity index and number of taxa were higher in natural substrates. In addition, cover of arborescent macroalgae was lower on artificial substrates. In conclusion, rip-raps do not function as surrogates of natural hard substrates in the study area since their shallow subtidal assemblages differ in terms of community structure, diversity and functionality. The deficient performance of such artificial structures could be attributed to the combined effects of abiotic factors and biotic processes, including substrate nature and roughness as well as differential grazing pressure

Estimation of mesospheric gravity wave momentum flux using Hybrid Doppler Interferometry

15th MST Radar WorkshopSession M6: Middle atmosphere dynamics and structureMay 31 (Wed), NIPR Auditoriu

Preliminary assessment of methanogenic microbial communities in marine caves of Zakynthos Island (Ionian Sea, Greece)

Mediterranean marine caves remain largely unexplored, while particularly limited information is available about the microbial life existing in these unique environments. The present study is a preliminary assessment of the composition of the active anaerobic microbial community colonizing the walls of newly explored systems of underwater caves and small cavities in Zakynthos Island. The interior of these caves is densely coated with egg-shaped, foam-shaped and filamentous biological structures that are characterised by a strong odor of hydrogen sulfide gas. A total of twelve structures scrapped from cave rocks were subjected to anaerobic cultivation for up to 208 days. Strong to moderate methanogenesis was observed in two different types of egg-shaped structures and one foam-like structure. Interestingly, this was observed in experiments that were performed at room temperature (i.e. 25oC) which is substantially lower than those typically considered optimum for methane production (e.g. 35oC). Analysis of the 16S rRNA genes revealed a clear dominance of archaea and bacteria closely related to known methane producers and sulfate reducers, including members of the families Methanomicrobiaceae, Desulfobulbaceae, Desulfobacteraceae, Desulfuromonaceae, Campylobacteraceae, Marinifilaceae, Clostridiaceae, Incertae Sedis – Family I & II. These results show that Mediterranean marine caves can host members of archaea and bacteria with potential biotechnological interest that deserve further investigation

Assessing the regional conservation status of sponges (Porifera): the case of the Aegean ecoregion

Sponges are among the less-studied benthic invertebrates as regards their extinction risk and conservation status. Herein, we evaluate the regional conservation status of sponges in the Aegean ecoregion (Eastern Mediterranean Sea), using the IUCN Red List criteria. We examined 20 sponge taxa falling into three categories: i) threatened species listed in Annex II of the Barcelona Convention, ii) bath sponge species (Annex III of the Barcelona Convention), and iii) Aegean endemics. The regional geographic range of the examined taxa was depicted on detailed distribution maps, based mostly on recent observations by the authors and literature data. When possible, population trends were estimated based on historical data, and threats were identified. The suggested regional conservation status of the examined sponge species is as follows: i) nine species were characterised as ‘Data Deficient (DD)’ due to limited available information; ii) seven species were assigned to the ‘Least Concern (LC)’ category; iii) the four harvested bath sponge species were assigned to the Endangered (EN) category, based on their population decline in the Aegean region during the past decades. The present evaluation, besides providing scientific data for the regional protection and management of sponge populations, can form a basis for wider assessment and consequent conservation of Porifera