Andreu Santín

Sponge assemblages dominate several distinctive, hard-bottom environments, being one of the most important structural organisms at several locations around the world. Although the Mediterranean sponge fauna is among the world's most studied, information is minimal for sponges from Mediterranean deep-sea areas compared to shallow waters, with most of the data deriving from indirect sampling methods or from by-catch specimens collected by bottom trawlers. Taking advantage of the footage and material collected during the Life + INDEMARES, ABIDES and ABRIC projects, the present thesis aims to shed light, by means of non-invasive methods, into the sponge communities occurring in two remarkable sites of the Catalano-Balearic Sea (northwestern Mediterranean Sea): The Site of Community Interest (SCI) of the Menorca Channel (Balearic archipelago), which is to become a future Marine Protected Area (MPA), and the Cold Water-Coral (CWC) communities recently discovered in the Blanes Canyon. Regarding the Menorca Channel SCI, this thesis characterized, by means of quantitative analyses of video transects, the main sponge assemblages occurring in the area, with a special focus on the geographical, bathymetrical and size-structure distribution of its most relevant habitat-forming sponge. Quantitative analysis of 85 video-transects (a total linear distance of 75 km), together with representative collections to confirm species identifications, allowed to discriminate six major assemblages, which mainly corresponded to differences in substrate type and depth. Highest sponge densities and abundances were concentrated in areas of high hydrodynamism, namely the rocky shoals offshore Cap Formentor and the Menorca Canyon’s head. Most of the studied species were dominated by small to medium size classes, suggesting pulse recruitment events. A clear depth-zonation pattern has been observed, going from the inner continental shelf to the upper slope. At the same time, the continental shelf harbored the presence of diverse and contrasting growth morphologies, yet the biggest forms occurred at the shelf edge and the upper slope. Regarding the identified assemblages, on the inner continental shelf, a semi-sciaphilous Axinellid assemblage dominated the rocky outcrops. Maërl beds on the inner continental shelf were dominated by Haliclona (Reniera) mediterranea, whereas the horny sponge Aplysina cavernicola and several other haliclonids mostly dominated maërl beds and rocky substrates of the outer shelf. Soft sediments on the shelf break hosted a monospecific Thenea muricata assemblage, whereas rocky substrates of the shelf break were characterized by a mixture of encrusting, columnar and fan-shaped sponges. Finally, the upper slope was dominated by Hamacantha (Vomerula) falcula and the hexactinellid Tetrodictyum reiswigi. This thesis highlights the presence of dense, well-preserved sponge populations in the Menorca Channel, and provides a baseline for their future monitoring once the MPA is declared, potentially serving as reference for other areas across the Atlanto-Mediterranean region. Regarding the Blanes canyon, the present thesis provides the first insight on the associated sponge fauna of its recently discovered CWC communities, while also reviewing the current knowledge of the sponge fauna dwelling in all the Mediterranean CWC provinces. In regards to the studied area, some rare species are cited for the first time in the Mediterranean or redescribed, while two of them, Hamacantha (Hamacantha) hortae and Hamigera bibiloni are new to science. At a basin scale, Mediterranean CWC appear as poriferan biodiversity hotspots, yet current diversity values on each site rather represent a small fraction of its actual fauna. Additionally, the existence of an endemic sponge fauna exclusively dwelling on CWC is refuted. Nonetheless, the sponge fauna thriving in Mediterranean CWC appears to be unique, and different from that of other Atlantic regions. Las comunidades de esponjas dominan multitud de entornos de fondo duros, siendo uno de los organismos estructurales dominantes en varias áreas del mundo. Aunque la fauna de esponjas mediterráneas se encuentra entre las más estudiadas del mundo, la información disponible actualmente es mínima para las esponjas que se encuentran en las zonas más profundas del mediterráneo en comparación con sus aguas más someras, y la mayoría de los datos disponibles han sido obtenidos mediante métodos de muestreo indirectos o de capturas accidentales por pesquerías de fondo. Aprovechando el metraje y material recogido durante los proyectos Life + INDEMARES, ABIDES y ABRIC, la presente tesis pretende arrojar luz, mediante métodos no invasivos, sobre las comunidades de esponjas que se dan en dos áreas destacadas del Mar Catalano-Balear (mar Mediterráneo noroccidental): el Sitio de Interés Comunitario (SCI) del Canal de Menorca (archipiélago balear), que se convertirá en un futuro Área Marina Protegida (AMP), y las comunidades de corales de agua fría recientemente descubiertas en el cañón de Blanes. En cuanto al SIC del Canal de Menorca, esta tesis caracterizó, mediante análisis cuantitativos de video-transectos, las principales comunidades de esponjas de la zona, con especial énfasis en la distribución geográfica, batimétrica y estructural de las especies formadoras de hábitat más relevantes. El análisis cuantitativo de 85 video-transectos (una distancia lineal total de 75 km), junto con el análisis de especímenes para confirmar la identificación de especies, permitió discriminar seis comunidades principales, que correspondían principalmente a diferencias en el tipo de sustrato y profundidad. Las mayores densidades y abundancias de esponjas se concentraron en áreas de alto hidrodinamismo, a...

Sponges are amongst the most difficult benthic taxa to properly identify, which has led to a prevalence of cryptic species in several sponge genera, especially in those with simple skeletons. This is particularly true for sponges living in remote or hardly accessible environments, such as the deep-sea, as the inaccessibility of their habitat and the lack of accurate descriptions usually leads to misclassifications. However, species can also remain hidden even when they belong to genera that have particularly characteristic features. In these cases, researchers inevitably pay attention to these peculiar features, sometimes disregarding small differences in the other “typical” spicules. The genus Melonanchora Carter, 1874, is among those well suited for a revision, as their representatives possess a unique type of spicule (spherancorae). After a thorough review of the material available for this genus from several institutions, four new species of Melonanchora, M. tumultuosa sp. nov., M. insulsa sp. nov., M. intermedia sp. nov. and M. maeli sp. nov. are formally described from different localities across the Atlanto-Mediterranean region. Additionally, all Melonanchora from the Okhotsk Sea and nearby areas are reassigned to other genera; Melonanchora kobjakovae is transferred to Myxilla (Burtonanchora) while two new genera, Hanstoreia gen. nov. and Arhythmata gen. nov. are created to accommodate Melonanchora globogilva and Melonanchora tetradedritifera, respectively. Hanstoreia gen. nov. is closest to Melonanchora, whereas Arhythmata gen. nov., is closer to Stelodoryx, which is most likely polyphyletic and in need of revision.

The jellyfish species that inhabit the Mediterranean coastal waters are not lethal, but their stings can cause severe pain and systemic effects that pose a health risk to humans. Despite the frequent occurrence of jellyfish stings, currently no consensus exists among the scientific community regarding the most appropriate first-aid protocol. Over the years, several different rinse solutions have been proposed. Vinegar, or acetic acid, is one of the most established of these solutions, with efficacy data published. We investigated the effect of vinegar and seawater on the nematocyst discharge process in two species representative of the Mediterranean region: Pelagia noctiluca (Scyphozoa) and Carybdea marsupialis (Cubozoa), by means of (1) direct observation of nematocyst discharge on light microscopy (tentacle solution assay) and (2) quantification of hemolytic area (tentacle skin blood agarose assay). In both species, nematocyst discharge was not stimulated by seawater, which was classified as a neutral solution. In P. noctiluca, vinegar produced nematocyst discharge per se, but inhibited nematocyst discharge from C. marsupialis. These results suggest that the use of vinegar cannot be universally recommended. Whereas in case of a cubozoan C. marsupialis sting, the inhibitory effect of vinegar makes it the ideal rinse solution, in case of a scyphozoan P. noctiluca sting, vinegar application may be counterproductive, worsening the pain and discomfort of the stung area.

Although the jellyfish species that inhabit the Mediterranean coastal waters are not lethal, their sting can cause severe pain and systemic effects that pose a health risk to humans. Despite the frequent occurrence of jellyfish stings, currently no consensus exists regarding the most appropriate first aid protocol among the scientific community. Over the years, several different rinse solutions have been proposed of which vinegar, or acetic acid, is one of the most noticeable as a rinse solution with efficacy data published. We investigated the effect of vinegar and seawater on the nematocyst discharge process in species representative of the Mediterranean region such as Pelagia noctiluca (Scyphozoa) and Carybdea marsupialis (Cubozoa) by means of: (1) direct observation on the nematocyst discharge by light microscope (Tentacle solution assay) and (2) the quantification of hemolytic area (Tentacle skin blood agarose assay). The nematocyst discharge of both species was not stimulated by seawater, and it was classified as a neutral solution. In P. noctiluca, vinegar produced nematocyst discharge per ser while inhibiting the nematocyst discharge of C. marsupilais. These results suggest that the use of vinegar cannot be universally recommended. While in case of a cubozoan C. marsupialis sting, the inhibitory effect of vinegar makes it the best rinse solution par excellence, in case of a scyphozoan P. noctiluca sting, its application can be counterproductive, worsening the pain and discomfort of the stung area.