You cannot conserve a species that has not been found: The case of the marine sponge Axinella polypoides in Liguria, Italy

Abstract

Detailed knowledge about the distribution of species in need of protection is required for the management of Marine Protected Areas, a major tool to reduce marine biodiversity loss. Such knowledge is deficient for most marine invertebrates. Axinella polypoides is a marine sponge included on the list of protected species by the Barcelona Convention (1976) and the Bern Convention (1987). This large and erect species has an important ecological role in habitat forming and benthic–pelagic coupling. Bathymetrical, geographical and ecological data over the last 60 years were collated from publications and reports, together with new surveys to assess the distribution and protection status in Liguria of A. polypoides. It identified a more widespread distribution than previously thought, which points at a general need for dedicated investigations on the occurrence of species that require protection. Bathymetrical distribution was trimodal, with peaks corresponding to different geomorphological settings: coastal cliff bases (around 38 m depth), inner shelf shoals (52 m) and rocks amidst coarse sediment on the outer shelf (79 m). Density was significantly greater at the shallowest depths. The species was mostly found in the coralligenous biocoenosis, in association with other characteristic species or forming a monospecific facies. On (sub)vertical cliffs, A. polypoides often exhibited an unusual cane shape, rather than the typical bushy morphology, thus causing confusion with the congeneric A. cannabina, a more southern species. Records of the latter in the Ligurian Sea therefore need confirmation. Only a minority (22.6%) of A. polypoides records were in Marine Protected Areas, the remainder being located in areas with no current environmental protection plans in place. While the occurrence of this species in MPAs remained stable over the decades, the only quantitative historical data available indicated that populations in non‐protected areas were declining owing to anthropogenic impacts (fishing and anchoring).

Structure from Motion Photogrammetry as an Effective Nondestructive Technique to Monitor Morphological Plasticity in Benthic Organisms: The Case Study of Sarcotragus foetidus Schmidt, 1862 (Porifera, Demospongiae) in the Portofino MPA

“…Sponges are well represented in the Mediterranean Sea, reaching their highest diversity in coralligenous and marine cave assemblages [19,20,42]. Although taxonomic assessments of the sponge communities in the Portofino MPA have been conducted since the 1990s [43,44], little is known about the conservation status and distribution of a wide range of these species [45]. In this context, the presence of a small population of S. foetidus, likely all arising from the same recruitment event, and therefore considered of the same age, provided a unique opportunity to (i) evaluate fine-scale changes at the individual level over time and (ii) observe negative effects potentially related to the unfolding of the current climate crisis.…”

Biodiversity Management in a Mediterranean National Park: The Long, Winding Path from a Species-Centred to an Ecosystem-Centred Approach

“…Management issues and responses from the PCNP and N-PCNP in the terrestrial realm (numbered T27 through T34) and the marine realm (numbered M21 through M29). These operations were not taken into account by Boudouresque et al ( [92]; see Tables 1 and 2 Although scientific research is an essential tool for management (we only protect well what we know well) [105], and although the PCNP has-since its establishment-been a hotbed for scientific research [4,93], we have not considered here the research programmes.…”

Biodiversity Monitoring in Mediterranean Marine Protected Areas: Scientific and Methodological Challenges

“…It is obviously impossible to establish conservation plans for something that has not been found yet [136]. To maximise the probability of finding what is searched for, inventories of species and habitats may benefit from suitability modelling, which allows predicting their occurrence on the basis of known environmental variables, such as depth, distance from the coast, bottom type, etc.…”