Diversity of Porifera in the Mediterranean coralligenous accretions, with description of a new species

Abstract

Temperate reefs, built by multilayers of encrusting algae accumulated during hundreds to thousands of years, represent one of the most important habitats of the Mediterranean Sea. These bioconstructions are known as “coralligenous” and their spatial complexity allows the formation of heterogeneous microhabitats offering opportunities for a large number of small cryptic species hardly ever considered.Although sponges are the dominant animal taxon in the coralligenous rims with both insinuating and perforating species, this group is until now poorly known. Aim of this work is to develop a reference baseline about the taxonomic knowledge of sponges and, considering their high level of phenotypic plasticity, evaluate the importance of coralligenous accretions as a pocket for biodiversity conservation.Collecting samples in four sites along the coast of the Ligurian Sea, we recorded 133 sponge taxa (115 of them identified at species level and 18 at genus level). One species, Eurypon gracilis is new for science; three species, Paratimea oxeata, Clathria (Microciona) haplotoxa and Eurypon denisae are new records for the Italian sponge fauna, eleven species are new findings for the Ligurian Sea. Moreover, seventeen species have not been recorded before from the coralligenous community. The obtained data, together with an extensive review of the existing literature, increase to 273 the number of sponge species associated with the coralligenous concretions and confirm that this habitat is an extraordinary reservoir of biodiversity still largely unexplored, not only taxonomically, but also as to peculiar adaptations and life histories.

Comparison between the sponge fauna living outside and inside the coralligenous bioconstruction. A quantitative approach

“…Our results are related to a small spatial scale, and a wider sample design could lead to different patterns (Andrew & Mapstone, 1987) and ratio between inner and outer sponges as evidenced for example in Bertolino et al (2013). In general, coralligenous assemblages can show a wide homogeneity at a large-scale, resulting in a lack of significant differences between separate locations (Piazzi et al, 2004), while at small scale, a high heterogeneity is always evident, limiting the definition of a standardized monitoring protocol valid at Mediterranean level (Zapata et al, 2013).…”

“…Just like the coral reefs, also for coralligenous accretions, it is possible to hypothesise that cryptic fauna may play a crucial functional role. The holes and crevices of this biogenic structure support a complex community dominated by suspension feeders (sponges, hydrozoans, tunicates, bryozoans, serpulids, mollusks), with sponges representing the most abundant taxon (Ballesteros, 2006;Bertolino et al, 2013). Bertolino et al (2013), sectioning big coralligenous blocks into slices identified the presence of 27 exclusively endolithic species giving an idea of the richness of this group inside the coralligenous substrata.…”

“…The holes and crevices of this biogenic structure support a complex community dominated by suspension feeders (sponges, hydrozoans, tunicates, bryozoans, serpulids, mollusks), with sponges representing the most abundant taxon (Ballesteros, 2006;Bertolino et al, 2013). Bertolino et al (2013), sectioning big coralligenous blocks into slices identified the presence of 27 exclusively endolithic species giving an idea of the richness of this group inside the coralligenous substrata. Moreover, it was stated that the diversity of coralligenous sponges has remained stable over a millennial span of time, and this extended stability may be related to the en- vironmental stability of the inner habitat of the conglomerates (Bertolino et al, 2014).…”

“…The coralligenous habitat is the most important biogenic structure in the Mediterranean Sea in terms of biodiversity, ecological and economic values (Boudouresque, 2004;Ballesteros, 2006;Bertolino et al, 2013).…”

Integración de el índice ESCA por medio de los macro-invertebrados sésiles

“…It is one of the most important coastal ecosystems of the Mediterranean Sea for distribution, biodiversity, productivity and role in the CO 2 cycle (Bertolino et al 2013, Martin et al 2014, Casas-Guell et al 2015. Coralligenous habitat is considered sensitive to human activities (Piazzi et al 2012, Cánovas Molina et al 2016) and has been included in the protection programme of European legislation (e.g.…”