CALYX NICAEENSIS (RISSO, 1826) (PORIFERA, DEMOSPONGIAE). IS IT A RARE AND THREATENED SPECIES? C. Cerrano 1*, A. Molinari 2, P. Bernat 2, R. Baldacconi 3, B. Calcinai 1 and V. Macic 4 1 DISVA, Università Politecnica delle Marche - [email protected] 2 RSTA, Cooperative Research Society, Genova, Italy 3 Reef Check Italia onlus, Italy 4 IMBK, Kotor, Montenegro Abstract As for many other benthic organisms, sponges are disappearing from several areas. The climate warming seems to be one of the most important causes involved in the phenomenon. Here we gather information on the distribution of the cup-shaped demosponge Calyx nicaeensis furnishing a first baseline for future monitoring and first observations regarding its natural history. Keywords: Porifera, Conservation, North-Western Mediterranean Introduction setacea. In conclusion, this species has a distribution highly fragmented, Climate warming is altering the phenology and the distribution of a wide limited in few spots of the Mediterranean, asking for adequate and urgent number of species both on land and underwater. To define which species are conservation measures at Mediterranean level [5]. more vulnerable it is urgent to draw future scenarios for possible mitigation measures. In the Mediterranean Sea,filter feeders such as sponges and octocorals are among the phyla most affected by extended mortality events [1, Tab. 1. Tab. 1. Historical and present finding of Calyx nicaeensis. 2]. Here we gather all the reports we found on the demosponge Calyx nicaeensis (Haplosclerida, Phloeodictyidae), a species that seems to be under fast regression in the NW Mediterranean Basin. The lack of a documented baseline does not allow knowing if this species is rare or actually endangered by anthropogenic impacts. Material and Methods To supply information about the distribution of Calyx nicaeensis, a detailed bibliographic study was performed, adding also unpublished record available on the web and recent records from Apulian coasts and Montenegro. Photo documentations allowed to highlight some peculiar aspects of the natural history of this species related to the collection of rolling coarse sediments and its asexual reproductive strategies (Fig. 1). Fig. 1. Fig.1 Calyx nicaeensis. A) Sediment accumulation in the exhalant cavity B) Asexual reproduction by basal buds. Results Distribution. This sponge has a wide bathymetric range (down to 400 m depth) [4] but is mainly reported from 5 to 55 m depth in many areas of Mediterranean Sea (Tab.1). Its habitat is both Posidonia oceanica meadows References and coralligenous concretions. When shallow, it is found in pre-cave 1 - Huete-StaufferC, et al. 2011. Paramuricea clavata (Anthozoa, conditions. C. nicaeensis, being with a vertical growth, in several cases was Octocorallia) loss in the MPA of Tavolara (Sardinia, Italy) due to a mass noted damaged by lost fishing lines. Sediment collection. Cup-shaped sponges mortality event. Mar. Ecol. 32: 107-116. inevitably entrap coarse sediments. These sponges have different strategies to 2 - Di Camillo C.G., et al. 2013. Sponge disease in the Adriatic Sea. Mar. Ecol. manage this mound of coarse particles in the exhalant cavity. C. nicaeensis 34: 62–71 likely tend to collapse the osculum when filled by sediments (Fig. 1A). 3 - Tortonese E., 1958. Bionomia marina della regione costiera fra punta della Asexual reproduction. This species shows a peculiar strategy of asexual Chiappa e Portofino (Riviera Ligure di Levante). Arch. Oceanogr. Limnol., 11 reproduction, producing buds from the sponge base (Fig. 1B). (2): 167-209. 4 - Vacelet J., 1960, Éponges de la Méditerrannée Nord-Occidentale récoltées Conclusions par le «Président Théodore Tissier » (1958), Revue des Travaux de l'Institut The findings of Calyx nicaeensis here reported cannot confirm an actual des Pêches Maritimes, 24(2), 258-272. regression phase, anyway this species is certainly disappeared from the 5 - De la Linde, A., Moreno, D., Maldonado, Manuel, 2008. RedBooK of Ligurian Sea after its finding in the ‘60s [3]. A recent documentation from Andalucian Invertebrates (in Spanish). Volumes I -IV Montenegro, allows mentioning as a threat for this species areas with human impacts (e.g. artisanal fishery, coastal constructions, diving, sewage) and invasive species such as the algae Caulerpa racemosa and Womersleyella 771 Rapp. Comm. int. Mer Médit., 40, 2013.