Letizia Sion

Comparing Deep-Sea Fish Fauna between Coral and Non-Coral “Megahabitats” in the Santa Maria di Leuca Cold-Water Coral Province (Mediterranean Sea)

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.

The demersal faunal assemblage of the north-western Ionian Sea (central Mediterranean): current knowledge and perspectives

Data reported in this article were collected in the context of several trawl surveys carried out in the north-western Ionian Sea in the last 25 years. An overview of the available information on the demersal resources in the area and an historical analysis at population and community levels is reported with the aim of identifying eventual significant changes over time. During the study period 1985–2006, a total of 365 species (41 cephalopods, 76 crustaceans, 33 chondroichthyes and 215 osteichthyes) were collected in the investigated area from 10 to 4000 m, updating the faunal lists of this area with 18 new records and one alien species for the Mediterranean. An increase in the species richness was observed throughout the study period. The historical analysis showed a low abundance of chondroichthyes and significant increases over time for cephalopods, crustaceans and osteichthyes during the study period 1985–2006. An increasing trend in density over time was also detected for some target species (Illex coindetii and Nephrops norvegicus) and an inverse significant correlation with the fishing effort was also shown. Nevertheless, a significant decrease in the median lengths over time was depicted for N. norvegicus and Parapenaeus longirostris. A decreasing trend in the total mortality (Z) and exploitation rates (E) with time was only observed for Mullus barbatus. An overexploitation condition was shown by P. longirostris and Merluccius merluccius during time while a moderate overexploitation was detected for M. barbatus and Aristaeomorpha foliacea over time. A state of almost equilibrium and an optimal exploitation were observed for N. norvegicus and Aristeus antennatus, respectively. The authors give rise to discussion on the fishing effort-exploitation rate-recruitment process to explain the trends shown in the north-western Ionian Sea.

The bathyal benthopelagic fauna in the north-western Ionian Sea: structure, patterns and interactions

The main knowledge acquired on the structure, patterns and interactions in the bathyal benthopelagic fauna in the north-western Ionian Sea is summarised in this article. Using faunal sampling along a depth range between 200 and 4000 m, a total of 41 cephalopods, 64 crustaceans and 183 fishes have been collected. Some are new findings for the study area and for many of the species the bathymetric distribution has been updated. Distinct faunal assemblages related to the upper slope (400–800 m), middle slope (800–1200 m) and lower slope (>1200 m) were identified using Abundance Biomass Comparison curves. Species abundance decreases across the bathymetric gradient, whereas the biomass increases to ∼1000 m and then decreases again. Beyond this bathymetry, species richness, evenness and diversity index decrease with depth. The distribution pattern ‘bigger–deeper’ was observed in some species and ‘smaller–deeper’ in others. Roccella canyon and the Santa Maria di Leuca coral bank were investigated in relation to the distribution of fauna, highlighting migration phenomena in the former and a refuge effect in the latter. The effects of hydrographic conditions and fishing were also examined for the deep-water commercial shrimps Aristaeomorpha foliacea and Aristeus antennatus.

Improving the Conservation of Mediterranean Chondrichthyans: The ELASMOMED DNA Barcode Reference Library

Cartilaginous fish are particularly vulnerable to anthropogenic stressors and environmental change because of their K-selected reproductive strategy. Accurate data from scientific surveys and landings are essential to assess conservation status and to develop robust protection and management plans. Currently available data are often incomplete or incorrect as a result of inaccurate species identifications, due to a high level of morphological stasis, especially among closely related taxa. Moreover, several diagnostic characters clearly visible in adult specimens are less evident in juveniles. Here we present results generated by the ELASMOMED Consortium, a regional network aiming to sample and DNA-barcode the Mediterranean Chondrichthyans with the ultimate goal to provide a comprehensive DNA barcode reference library. This library will support and improve the molecular taxonomy of this group and the effectiveness of management and conservation measures. We successfully barcoded 882 individuals belonging to 42 species (17 sharks, 24 batoids and one chimaera), including four endemic and several threatened ones. Morphological misidentifications were found across most orders, further confirming the need for a comprehensive DNA barcoding library as a valuable tool for the reliable identification of specimens in support of taxonomist who are reviewing current identification keys. Despite low intraspecific variation among their barcode sequences and reduced samples size, five species showed preliminary evidence of phylogeographic structure. Overall, the ELASMOMED initiative further emphasizes the key role accurate DNA barcoding libraries play in establishing reliable diagnostic species specific features in otherwise taxonomically problematic groups for biodiversity management and conservation actions.

Bioecological Study of the Benthic Communities on the Soft Bottom of the Vlora Gulf (Albania)

Abstract Data on the soft bottom benthic communities of the Vlora Gulf along the Albanian coast were collected in the context of the international Centro Internazionale di Scienze del Mare (CISM) project funded by the Apulian region. The present study investigated and mapped the different communities inside the Gulf of Vlora, Albania, which are continuously affected by various natural and anthropogenic sources. Two research cruises were carried out in the Vlora Gulf during May 2007 and January 2008. During the first exploratory survey, the depth and morphology of the soft bottom was identified with a multibeam echo sounder and the Side-Scan–Sonar system; a preliminary map of the biocoenosis was created and a sampling plan was defined. In the second survey, 58 sampling stations were established in the study area using Van Veen grabs and scuba dives. A total of 151 taxa were identified (1 Foraminifera, 6 Cnidaria, 3 Nemertea, 2 Sipuncula, 36 Mollusca, 53 Annelida, 25 Crustacea Decapoda, 7 Bryozoa, 15 Echinodermata, 1 Hemichordata, and 2 Tunicata); 54 species were reported for the first time in Albania. The analyses showed there were three main habitats in the investigated area: the biocoenosis of terrigenous mud; a wide, muddy matte of Posidonia oceanica; and the narrow residual areas of P. oceanica meadows. The present study represents the first experience in mapping the benthic biocoenosis of the Vlora Gulf of Albania and shows a progressive decay of the benthic communities in the area, especially if compared with the previous few studies.

A Holistic Approach to Fishery Management: Evidence and Insights from a Central Mediterranean Case Study (Western Ionian Sea)

The new Common Fisheries Policy (CFP) is designed to represent an appropriate response to the uncertainties and challenges facing the fisheries sector. It also adopts a holistic approach to fisheries management, considering all factors driving fishers’ behavior, and ultimately, the long-term maintenance of living resources. The most reliable way to pursue these aims could be represented by a change in the exploitation pattern, in order to guarantee the sustainability of fisheries without compromising their socioeconomic viability. In this paper, the demersal fisheries of the Ionian Sea (Geographic Sub-area [GSA] 19) were analyzed with respect to their spatial, temporal, economic, and biological characteristics in terms of four key species for fisheries, namely European hake, red mullet, giant red shrimp, and deep-water rose shrimp. Specifically, 1) a quantitative procedure was applied to break down the whole system (including small-scale fleet components) into a series of fishing grounds using input data about fishing efforts; 2) the different fleet segments were defined as a combination of main gear and fishing grounds; 3) the effort and production by fleet segment were derived according to biological samplings of commercial data (Data Collection Framework for the collection and management of fisheries data, DCF), information on localization of nursery and spawning grounds, and expert knowledge; and 4) all this information was used to feed a bioeconomic modelling tool (BEMTOOL), and to explore alternative exploitation patterns. A series of scenarios including the status quo were defined, starting from the actual management approach based on temporal fishing closure. The results showed that significant improvements in the exploitation pattern could be achieved by setting up spatial and/or temporal gear-specific bans of the fishing activity. More specifically, scenarios based on a 3-month fishing ban for trawlers are expected to provide high rebuilding of the spawning stock biomass (SSB) for all target stocks, and at the same time, result in a remarkable reduction of discards. When combined with a seasonal fishing ban for small-scale fleets equipped with nets and longlines, this approach could lead to a significant improvement in all indicators, but especially the SSB of the exploited species.

Distribution and bio-ecological features of Posidonia oceanica meadows along the coasts of the southern Adriatic and northern Ionian Seas

An update of the spatial distribution and bio-ecological features of Posidonia oceanica (L.) Delile meadows spread along the coasts of the southern Adriatic and northern Ionian Seas (Apulia region, southern Italy) is reported. Mapping carried out in 2004 indicated a remarkable reduction in the spatial distribution of P. oceanica meadows in the southern Adriatic Sea, mostly northwards of Bari, when compared with 1991 data. By contrast, in the northern Ionian Sea, the spatial distribution seems to be more stable. The P. oceanica meadows covered ∼330 km2 distributed along a total of 320 linear km coastline, mostly on the southern side of Apulia. Within natural variability, the differences in bio-ecological features could be due mainly to the presence of anthropic disturbance (urban, industrial and tourist pressure) rather than a significant geographical gradient between the Adriatic and Ionian Seas. However, the mean density values recorded in almost all the Adriatic stations fall within the ‘lower sub-normal density’ (LSD) range. By contrast, the mean density values observed in the Ionian meadows were generally within the ‘normal density’ (ND) range.

Occurrence of the basking shark Cetorhinus maximus (Gunnerus, 1765) (Lamniformes: Cetorhinidae) in the central-eastern Mediterranean Sea

Abstract The presence of the basking shark Cetorhinus maximus (Lamniformes: Cetorhinidae) in the central-eastern Mediterranean Sea has been documented by means of 15 sightings and two accidental catches which occurred from February 2011 to January 2014 in the northwestern Ionian and southern Adriatic Sea. Specimens were observed exhibiting typical feeding behaviour, swimming slowly on the surface, during each sighting. In the case of the accidental catches, the basking shark specimens were released still alive by local fishermen. The observed specimens measured between 4 and 9 m in total length (TL). The sightings could be due to an increase in effort in the monitoring of the species occurring in the Mediterranean Sea as a consequence of a rise interest in the conservation of threatened species.

Review of the literature on age and growth of grenadiers in the Mediterranean and new data on age of Trachyrincus scabrus (Macrouridae) in the Ionian Sea

This paper reviews the existing literature on the age and growth of grenadiers in the Mediterranean Sea and provides new data on ageing of Trachyrincus scabrus in the North-western Ionian Sea (Central Mediterranean). Most studies have been carried out through otolith readings. Seasonal otolith formation also appears to be a general trend in grenadier fish in the Mediterranean even though it seems to be related to fluctuations in feeding and activity patterns. From examined literature age ranges of macrourids in the Mediterranean Sea varied from young-of-the-year (age 0) to a maximum ages of 23 years. There is a general agreement on the growth pattern of the species in the different geographic areas. T. scabrus was collected in the North-western Ionian Sea at depths between 400 and 1200 m during four seasonal trawl surveys. The minimum and maximum sizes of the whole sampled population were between 58 and 217 mm PAL. Otoliths were removed from 216 specimens. Backcalculation was performed and a maximum age of 10 years was determined. The following von Bertalanffy growth parameters were estimated for the whole sampled population: L∞ = 247.44 ± 8.39 mm PAL; k = 0.125 ± 0.010/year; t0 = −1.921 ± 0.127.

Cold-water coral communities in the Central Mediterranean: aspects on megafauna diversity, fishery resources and conservation perspectives

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.