{"id":6557,"date":"2024-03-07T01:00:45","date_gmt":"2024-03-07T00:00:45","guid":{"rendered":"https:\/\/vidamarina.info\/?p=6557"},"modified":"2025-01-10T09:33:29","modified_gmt":"2025-01-10T08:33:29","slug":"heterobranch-sea-slugs-from-blanes-costa-brava-ne-spain","status":"publish","type":"post","link":"https:\/\/vidamarina.info\/?p=6557","title":{"rendered":"Heterobranch sea slugs from Blanes (Costa Brava, NE Spain)"},"content":{"rendered":"

Manuel Ballesteros 1, 2<\/sup> & Miquel Pontes 2
\n<\/sup><\/strong>1<\/sup> Emeritus Professor, Universitat de Barcelona, mballesteros@ub.edu
\n2<\/sup> VIMAR, Vida Marina<\/p>\n

Abstract<\/strong><\/h4>\n

The coast of Blanes represents the southern entrance to the famous Catalan Costa Brava, a rugged, steep and very jagged rocky coast, with numerous inlets with beaches of coarse sand and which meanders for just over 200 km up to the French border. Its extraordinary submerged fauna and flora have attracted numerous SCUBA divers from all over the world for decades. Sea slugs in a broad sense (formerly \u201copisthobranchs\u201d) from the Blanes coast have been studied for more than 40 years by researchers of the University of Barcelona. In this work we present a compilation of the biodiversity of sea slugs cited in the coast of Blanes and observed or collected since 1976 to the present day. We also present the results of an unpublished work carried out at Punta de Santa Anna on a rocky wall located off the Blanes port breakwater, where quantitative visual censuses of sea slug populations were carried out for 14 months, analyzing their absolute abundance, the distribution of the species during the different seasons of the year and the biodiversity index of the different censuses. In total, 139 species of sea slugs have been determined to live on the Blanes coast, making this locality one of the best known for this type of fauna on all the Iberian coast.<\/p>\n

Introduction<\/strong><\/h4>\n

Blanes is a small village located at 65 km North of Barcelona, Spain. It is the southern limit of the famous \u201cCosta Brava\u201d that runs from Blanes to the north, for more than 100 km, until the French border. Possibly one of the richest hard bottom marine communities from the western Mediterranean are located at the Costa Brava littoral, specially at the Medes Islands (Ros et al<\/em>., 1984). Being Blanes the Costa Brava diving spot nearest to Barcelona, and the fact that it holds the CEAB (Centre d\u00b4Estudis Avan\u00e7ats de Blanes) scientific station, made the marine hard and soft bottoms off Blanes ones the best known for the whole Catalonia coast (Bibiloni, 1980; Pinedo et al<\/em>., 1997; Sard\u00e1 et al<\/em>., 1999).<\/p>\n

The \u201copisthobranch\u201d fauna of Catalan coast (NE Spain) begins to be well known since the 1970\u00b4s when several scientists conduct systematic samplings mainly as research for their PhD (Ros, 1973; Ballesteros, 1980). Subsequently, other researchers have emerged from the so-called citizen science and Internet platforms (M@re Nostrum; GROC; OPK) dedicated to the biodiversity of these mollusks that have greatly increased their knowledge. These samplings have allowed the Catalan littoral to be the best known of biodiversity \u201copisthobranch\u201d fauna (257 different species, Ballesteros et al<\/em>., 2016) from the whole Spanish Iberian littoral. Just one of these groups of \u00abopisthobranchs\u00bb, the nudibranchs, accounts for more than 150 species already known in Catalan waters (Ballesteros et al<\/em>, 2019).<\/p>\n

Some studies on the biodiversity of \u201copisthobranchs\u201d in specific localities have been carried out on the Catalan coast (NE Spain): Ballesteros (1984) who reported 21 species in the locality of Cubelles (Costa Daurada); Dom\u00e8nech et al. (2002) carried out in Port Lligat (Cadaqu\u00e9s, N Costa Brava), where they recorded 45 species; Dacosta et al. (2010) who recorded a total of 48 different species in Es Caials (Cadaqu\u00e9s, N Costa Brava); Ballesteros et al. (2015) with 94 species recorded at PNMMBT Marine Protected Area (L\u2019Estartit, Girona, Spain); Parera et al. (2020), who observed 73 species in the coastline of the city of Barcelona or VIMAR Vida Marina research group unpublished records, accounting for 110 species at PNMMBT Marine Protected Area (L\u2019Estartit, Girona, Spain) in 2023.<\/p>\n

In the case of \u201copisthobranchs\u201d more than 40 years of collecting samples at the Punta de Santa Anna and the very close Cala Sant Francesc, both from the Blanes littoral, together with specimens collected in the extensive commercial trawling grounds off Blanes (Dom\u00e8nech et al<\/em>., 2006) and the specimens from the malacological collection of Llu\u00eds Dantart (Toll & Ballesteros, 2017) have permitted to us to list 139 \u201copisthobranch\u201d species, meaning that 54% of all the known species for the whole Catalan littoral (Ballesteros et al<\/em>. 2016) are recorded in just one locality.<\/p>\n

Although sea slugs have been intensively studied in numerous coastal or marine areas in all oceans, few studies have been carried out at an ecological level in specific areas. To point out, for example, the work by Miller (1962) on the life cycles of some intertidal nudibranchs on the Isle of Man (U.K.), the extensive work by Nybakken (1978) on the ecology of intertidal nudibranch populations off the coast of California, or that of Goddard et al. (2020, 2021) who carried out a twelve-year long study on the abundance and presence of marine heterobranch species in a couple of locations of the Californian coast. There are no known data on subtidal ecological studies dedicated to \u201copisthobranchs\u201d.<\/p>\n

Here we present the list of the \u201copisthobranch\u201d species that have been recorded or collected in Blanes littoral and the results of an unpublished quantitative study about the ecology of \u201copisthobranch\u201d populations throughout a year cycle, made in a sublittoral sciophyllic vertical wall from 0 to 10 m depth.<\/p>\n

In this article, the term \u201copisthobranchs\u201d is repeatedly cited, which is the traditional taxonomic name applied to sea slugs in a broad sense. For the last two decades, and with the knowledge provided by molecular biology, the different groups of \u00abopisthobranchs\u00bb have been integrated into the Gastropoda subclass of Heterobranchia. For the nomenclature and taxonomy of the different species, we follow the proposals indicated in the WoRMS (2023) database.<\/p>\n

Methodology<\/strong><\/h4>\n

The \u201copisthobranchs\u201d species in the present list have been collected and\/or observed:<\/p>\n