Coralligenous habitat results from a multi-stratified accumulation of crustose coralline algae and animal builders in a dynamic equilibrium with disruptive agents. The result is a complex architecture crossed by crevices and holes. Due to this three-dimensional structure, the coralligenous habitat may host a rich and diversified fauna, more abundant than in any other Mediterranean habitat. Unfortunately, very few data are available about the cryptic fauna that lives inside the conglomerate. As already reported for coral reefs, the cryptic fauna plays an important role in the exchange of material and energy between water column and benthic assemblages. In this study, we compare the sponge community present inside and outside the coralligenous framework of the Portofino Promontory (Ligurian Sea) at different depths (15 and 30 meters) not only in terms of taxonomic diversity but, for the first time, also in terms of biomass. Sponges present on the surface of each block were collected, weighed and identified; after the dissolution of blocks in HCl, target cryptic sponges were separated from other organisms, weighed, and identified. We recorded a total of 62 sponge species. The average number of sponge taxa occurring outside the coralligenous accretions is lower than the number of taxa identified inside. This pattern is confirmed also regarding sponge biomass. These results underline that studies focused on coralligenous functioning should take into account the important contribution of cryptic fauna, as recently evidenced also for tropical reef habitats.

Depth range
15- 30 m

Mesophotic “mentions”
0 x (total of 2985 words)

Classification
* Presents original data
* Focused on 'mesophotic' depth range
* Focused on 'temperate mesophotic ecosystem'

Fields
Biodiversity

Focusgroups
Porifera (Sponges)

Locations
Italy - Ligurian-Tyrrhenian

Platforms
SCUBA (open-circuit or unspecified)