Macro- and megafauna were recorded in the submarine Bari Canyon (southern Adriatic Sea, Mediterranean Sea) during an oceanographic cruise carried out in May-June 2012 and an experimental fishing survey conducted in November 2013. During the former, a total of 20 benthic samples were taken using a Van Veen grab at depths between 268 and 770 m and 4 deployments of a baited lander, for about 43 hours of video records, were carried out at depths between 443 and 788 m. During the latter, 8 longline fishing operations were conducted from 338 down to 612 m. Eighty-five living benthic and benthopelagic species were recorded: 29 Porifera, 1 Cnidaria, 2 Mollusca, 11 Annelida, 1 Arthropoda, 19 Bryozoa, 3 Echinodermata and 19 Chordata. A total of 51 species are new records for the Bari Canyon, 29 new records for the Adriatic Sea. Among the Porifera Cerbaris curvispiculifer is a new addition for the Italian Sponge Fauna. The first certain record of living specimens for the bryozoan Crisia tenella longinodata is reported. A total of 6 Mediterranean endemic species have been identified: 4 Porifera and 2 Annelida. The bathymetric range of some species has been extended. New information acquired for deep sea species confirms their importance in the structure of cold-water coral communities. This study has updated the knowledge on the biodiversity of the Adriatic Sea, as well as of the Bari Canyon in particular, one of the sites designated as “jewels of the Mediterranean” for which urgent conservation measures are needed.
Two experimental longline surveys were carried out in the Santa Maria di Leuca (SML) cold-water coral province (Mediterranean Sea) during May–June and September–October 2010 to investigate the effect of corals on fish assemblages. Two types of “megahabitat” characterized by the virtual absence of fishing were explored. One was characterized by complex topography including mesohabitats with carbonate mounds and corals. The other type of megahabitat, although characterized by complex topographic features, lacks carbonate mounds and corals. The fishing vessel was equipped with a 3,000 m monofilament longline with 500 hooks and snoods of 2.5 m in length. A total of 9 hauls, using about 4,500 hooks, were carried out both in the coral megahabitat and in the non-coral megahabitat during each survey. The fish Leucoraja fullonica and Pteroplatytrygon violacea represent new records for the SML coral province. The coral by-catch was only obtained in the coral megahabitat in about 55% of the stations investigated in both surveys. The total catches and the abundance indices of several species were comparable between the two habitat typologies. The species contributing most to the dissimilarity between the two megahabitat fish assemblages were Pagellus bogaraveo, Galeus melastomus, Etmopterus spinax and Helicolenus dactylopterus for density and P. bogaraveo, Conger conger, Polyprion americanus and G. melastomus for biomass. P. bogaraveo was exclusively collected in the coral megahabitat, whereas C. conger, H. dactylopterus and P. americanus were found with greater abundance in the coral than in the non-coral megahabitat. Differences in the sizes between the two megahabitats were detected in E. spinax, G. melastomus, C. conger and H. dactylopterus. Although these differences most probably related to the presence-absence of corals, both megahabitats investigated play the role of attraction-refuge for deep-sea fish fauna, confirming the important role of the whole SML coral province as a refuge area from fishing.
New cold‐water coral (CWC) sites were recorded along the Apulian margin (Central Mediterranean). The species composition and depth distribution of CWCs were updated. A distribution of the CWC sites coincident with the course of the dense‐water masses that flow between the Southern Adriatic and Northern Ionian was confirmed. The faunal assemblages of five of these CWC sites were investigated and compared using experimental longlines during the spring–summer and autumn–winter seasons, between 2010 and 2014. Differences in ecological variables amongst the sites in each season were evaluated by means of a set of univariate and multivariate methods (analysis of variance, permutational multivariate analysis of variance, non‐metric multidimensional scaling). Although some differences were detected in relation to the different depths examined during spring–summer, the CWC sites showed similar features in terms of species richness and diversity as well as in the abundance of the same fish species (Galeus melastomus, Conger conger, Helicolenus dactylopterus, Merluccius merluccius, Phycis blennoides and Pagellus bogaraveo) most probably because of the distribution of adult specimens in structurally complex and heterogeneous habitats, which act as a potential ‘refuge network’ with respect to commercial fishing. The presence of maturing and mature individuals as well as post‐reproductive females indicates that these CWC sites also act as spawning areas, representing a potential ‘renewal network’ for the fish populations. The term ‘network’ used here refers to several similar subsystems (CWC sites) that play the same ecological role in a wider system (Apulian margin). These CWC communities need coherent conservation measures and management strategies according to the Ecosystem Approach to Fisheries.
Canyons play a fundamental role in enhancing the abundance and diversity of marine organisms through the transport of organic matter and food resources, the presence of complex physical habitats and the absence of trawl fishing. During four baited lander deployments carried out in the Bari Canyon (Southern Adriatic Sea, Central Mediterranean), at depths of 443–788 m, about 43 h of video records were taken, for a total of 619,200 video frames. A total of 12 benthopelagic fish species (five chondrichthyes and seven osteichthyes) were identified. The blackspot seabream (Pagellus bogaraveo) was the most often observed fish species. The depth of 787 m represents a new depth record for this fish in the Adriatic Sea. Groups of up to 40 individuals of P. bogaraveo were attracted to the bait and were shown in single frames. The individuals were observed both exploring the area and feeding actively on the bait. The European conger (Conger conger) was recorded at each deployment. Clear scavenger behaviour was also observed in this teleost fish and in the shark Etmopterus spinax. The shark species Centrophorus granulosus and Hexanchus griseus, which are considered ‘vulnerable’ on the published IUCN Mediterranean Regional Red List, were also recorded but, although attracted by the bait, they were never seen feeding on it. Other fish species, harvested on fishing grounds, such as Merluccius merluccius, Helicolenus dactylopterus and Polyprion americanus, were also recorded. This study represents the first in situ documentation, at very low impact, of the fish fauna in the Bari Canyon, providing new insights into its small scale distribution and behaviour, the first in situ direct observation of the variable feeding behaviour of P. bogaraveo and its gregarious habits, as well as indicating that this canyon could act as a refuge area for species that are vulnerable to fishing on the open slope.
In the last two decades, many new living cold-water coral (CWC) sites throughout the Mediterranean basin have been discovered and investigated. As part of oceanographic cruises, using ROVs and towed cameras, and trawl and longline surveys as well as records from fishermen, a belt of CWC communities has been identified along the Apulian continental margin (Central Mediterranean). The most investigated CWC communities are those of the Santa Maria di Leuca (SML) CWC province (northern Ionian Sea) and Bari Canyon (BC) (southern Adriatic Sea). These communities are mainly structured by the habitat-former species Madrepora oculata and, to a lesser extent, by Lophelia pertusa together with Dendrophyllia cornigera, solitary species, such as Desmophyllum dianthus, black coral, such as Leiopathes glaberrima, sponges (e.g., Pachastrella monilifera, Poecillastra compressa), serpulids, boring clams and colonies of bryozoans. CWC sites are biodiversity hot-spots, that act as "Essential Fish Habitats" for commercial species and through the spill-over effect might contribute to the renewal of stocks in neighbouring fishing grounds, providing ecosystems' goods and services. Despite their particular features, CWC areas along the Apulian slope are impacted by different anthropogenic activities. Fishermen operate close and around these areas with the aim of obtaining greater catches and sizes of commercial species. Although there are many conservation proposals for CWC habitats and a Fisheries Restricted Area established for Santa Maria di Leuca CWC province, human pressure is still very strong, due to the lack of adequate conservation measures. An effective system of monitoring, control and surveillance will be fundamental to meet the conservation objectives and to reach the Good Environmental Status as part of the Marine Strategy Framework Directive.
The objective of this study is to provide additional evidence of the utilization of Cold-Water Corals (CWC) and Submarine Canyons (SC) by fishes as areas for growing to maturity and to reproduce and thus for the classification of CWC as Essential Fish habitats (EFH). Data were collected with longline experimental surveys carried out during spring-summer and autumn-winter from 2010 to 2014, in different CWC sites distributed along the Apulian margin: Gondola Slide (GS), Bari Canyon (BC), Monopoli (Mn) and Santa Maria di Leuca (SML). In the present study the reproductive phase of Galeus melastomus, Conger conger, Helicolenus dactylopterus, Merluccius merluccius, Pagellus bogaraveo and Phycis blennoides collected in the abovementioned CWC communities has been analysed with respect to fish size. Maturing and mature individuals as well as post-reproductive specimens of G. melastomus, H. dactylopterus and M. merluccius were observed in all the investigated CWC sites. Mature gonads were also found in the other three species, although the investigated period was outside their reproductive peak, indicating that these CWC sites act as spawning areas and therefore as a potential 'renewal network' for fish species exploited in the neighbouring fishing grounds. This provides a strong argument for the categorization of CWC as EFH in the design of management programs.
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