Sicilian Waters Research Articles

The simultaneous stable isotope analysis of skin and blood gives insights on habitats shifts in Mediterranean loggerhead turtles (Caretta caretta, Linneus 1758)

Marine turtles are key indicator species of ecosystem function and environmental health, however, many of their life-history features remain cryptic. Particularly, the understanding of their year-round feeding habits is critical to establish the effect of contaminants exposure through the marine food web and their adverse health consequences. Here, 24 Mediterranean loggerhead turtles (Caretta caretta) with problems related to plastic ingestion were wild-caught alive in the Tyrrhenian Sea (Central Mediterranean), their bloods and epidermis were sampled, and their carbon and nitrogen isotope ratios analyzed. Generally, δ13C values did not correlate between tissues, while δ15N values showed a linear relationship, suggesting more variability in feeding habitats than in trophic levels among turtles. For all animals, the calculated stable isotope niche was wider for skin than for blood, which support a temporal difference in feeding locations. Blood probably indicated the consumption of recent pelagic food, and skin of older more neritic prey. Bayesian mixing models were implemented for turtles sampled in Sicilian waters and results suggested that, generally, prey at low trophic levels were preferred to those at higher trophic positions. Our results support the utility of sampling blood and epidermis from alive and wild animals to investigate simultaneously newer and older ecological features of sea turtles. Further studies should aim on investigating animals in both good health and with detectable disease issues, to understand how much different threats and healthy status can influence Mediterranean loggerhead turtles’ feeding ecology.

Cultural Encounter, Race, and a Humanist Ideology of Empire in the Art of Trecento Venice

Cultural Encounter, Race, and a Humanist Ideology of Empire in the Art of Trecento Venice

Isolation and Identification of Luminescent Bacteria in Deep Sea Marine Organisms from Sicilian Waters (Mediterranean Sea)

Luminescent bacteria are a fascinating component of marine microbial communities, often related to the light emissions in deep sea marine organisms. They are mainly affiliated with specific phylogenetic groups, such as Photobacterium, Vibrio, and Photorhabdus, and are sometimes involved in symbiotic relationships. However, the luminescence of some marine organisms remains a poorly understood process, and it is not always certain whether their luminescence is attributable to associated luminescent bacteria. In this study, for the first time, luminescent bacteria were isolated from two deep sea organisms, namely, the cephalopod Neorossia caroli and the teleost Chlorophthalmus agassizi. The isolation was carried out on glycerol-supplemented medium, and the search for the luxAB gene was performed on all isolates as a complementary tool to the culture-dependent techniques to detect bioluminescence by molecular approach. The optimum of salinity, temperature, and pH was evaluated by physiological tests for all isolates. The production of extracellular polymeric substances was also preliminarily screened. A total of 24 luminescent isolates were obtained, with an abundance from C. agassizi specimens. All the isolates were taxonomically characterized and were related to different species of Photobacterium, with the exception of Vibrio sp. CLD11 that was from C. agassizi. The luxAB gene was detected in about the 90% of the analysed strains.

Bottlenose Dolphins and Seabirds Distribution Analysis for the Identification of a Marine Biodiversity Hotspot in Agrigento Waters

The aim of this study is to evaluate the presence of biodiversity hotspots in Agrigento waters (Mediterranean Sea) to define the conservation area for bottlenose dolphins (Tursiops truncatus) and seabirds (Calonectris diomedea, Puffinus yelkouan, and Hydrobates pelagicus), according to European directives. With this purpose, the maximum entropy algorithm (MaxEnt) was applied to the sighting points of the focal species. They co-occur in the study area and have been documented to forage behind trawlers. In this study, a fishing rate was designed and used as an explanatory variable of the species distribution, together with physiographic variables. Data were collected during 68 surveys in the waters off Agrigento province. MaxEnt models showed a strong predictive power, with distance from the coast being the greatest predicting variable, followed by slope, depth, and fishing rate. For all the species considered, the probability of presence increased as the fishing rate grew. Cartographic analysis revealed one area shared by the species, which occupies 529 km2, from the shoreline to 100 m depth. This study increases knowledge on the distribution and habitat preferences of the target species in the Sicilian waters. Evaluating the influence of fisheries is a promising method that needs further testing to apply effective management measures.

Batoid Abundances, Spatial Distribution, and Life History Traits in the Strait of Sicily (Central Mediterranean Sea): Bridging a Knowledge Gap through Three Decades of Survey.

Simple SummaryBatoid species are cartilaginous fish commonly known as rays, but they also include stingrays, electric rays, guitarfish, skates, and sawfish. These species are very sensitive to fishing, mainly because of their slow growth rate and late maturity; therefore, they need to be adequately managed. Regrettably, information on life history traits (e.g., length at first maturity, sex ratio, and growth) and abundance are still scarce, particularly in the Mediterranean Sea. In this regard, the present study focuses on the Strait of Sicily (Central Mediterranean) and aims to improve knowledge gained through scientific survey data. In particular, abundance data, spatial distribution, and some life history traits are herein presented. In the investigated area, the biomass trends of the batoids indicated a slight recovery even if few species showed a depletion. Considering the importance of this taxon for maintaining the marine ecosystem equilibrium, management measures are desirable.Batoid species play a key role in marine ecosystems but unfortunately they have globally declined over the last decades. Given the paucity of information, abundance data and the main life history traits for batoids, obtained through about three decades of bottom trawl surveys, are presented and discussed. The surveys were carried out in two areas of the Central Mediterranean (South of Sicily and Malta Island), in a timeframe ranging from 1990 to 2018. Excluding some batoids, the abundance trends were stable or increasing. Only R. clavata, R. miraletus, and D. oxyrinchus showed occurrence and abundance indexes notable enough to carry out more detailed analysis. In particular, spatial distribution analysis of these species highlighted the presence of two main hotspots in Sicilian waters whereas they seem more widespread in Malta. The lengths at first maturity (L50) were 695 and 860, 635 and 574, and 364 and 349 mm total length (TL), respectively, for females and males of D. oxyrinchus, R. clavata, and R. miraletus. The asymptotic lengths (L∞) and the curvature coefficients (K) were 1365 and 1240 (K = 0.11 and 0.26), 1260 and 1100 (K = 0.16 and 0.26), and 840 and 800 mm TL (K = 0.36 and 0.41), respectively, for females and males of D. oxyrinchus, R. clavata, and R. miraletus. The lack of detailed quantitative historical information on batoids of Sicily and Malta does not allow to analytically judge the current status of the stocks, although the higher abundance of some species within Malta raises some concern for the Sicilian counterpart. In conclusion, suitable actions to protect batoids in the investigated area are recommended.

Türkiye'nin Akdeniz Kıyılarında Nadir Görülen Echeneis naucrates'in Son Kaydı

One specimen of live sharksucker was caught with a bottom trammel net in Taşucu Bay, south-eastern coast of Turkey, at 1 m depth on May, 2021. Meristic parameters were determined by fin ray counts and metric parameters were measured from the photos of the specimen. Excluding the recent record in Antalya Gulf, previous records of this species occurred later than May, generally in July in the Mediterranean Sea as well as in the Aegean Sea. The biometrical measurements were different in Taşucu Bay compared to those caught from the Aegean Sea and the central Mediterranean Sea (Tunisian and Sicilian waters), but relatively similar to those reported from Croatia. Major discriminative variables, albeit less significant in individuals from the central Mediterranean, were the number of anal, pectoral and dorsal fin rays. Numbers of suction disc laminae were higher in individuals from the central Mediterranean Sea and New Zealand than those from the Turkish coasts (all 21 disc laminae). The statistical analyses (Principal Component and Discriminant analyses) affirmed successful use of meristic parameters to differentiate the biometric characteristics of the species from the Aegean Sea, the central and eastern Mediterranean Sea. The length-weight relationship showed that the species had a negative allometric growth.

New contribution on the distribution and ecology of Dendrophyllia ramea (Linnaeus, 1758): abundance hotspots off north‐eastern Sicilian waters

Abstract Dendrophyllia ramea is a poorly known arborescent scleractinian coral, whose worldwide distribution is limited to the southern part of the Mediterranean basin, and to the Atlantic Ocean between Macaronesia and Gulf of Cadiz. The geographical distribution and abundance of D. ramea were herein updated, considering a total of 19 records, seven of which have never previously been reported in scientific papers. Between 2010 and 2017, five Remotely Operative Vehicle surveys carried out along the Sicilian coast recorded 89 colonies. No exhaustive data on density and ecology of this species have been published to date. Data for two areas off the north‐eastern Sicilian waters (Aeolian Island and Gulf of Patti) are reported, including the species’ bathymetric distribution, abundance, population density, colony morphometry, population size structure and surrounding habitat description. Size structure and density of D. ramea populations were compared with lost fishing gear density. Around the Aeolian Islands, where little lost fishing gear was observed, the D. ramea population was denser compared with the populations at two sites within the Gulf of Patti, where a greater amount of lost fishing gear was observed. The analysis of D. ramea size classes (single corallite, 2–5 polyps, >5 polyps) at different sites showed that impact varied with fishing gear typology: while lines damage the branches of larger colonies, nets can completely remove them. The limited distribution of D. ramea in some areas also makes this species very vulnerable to impacts such as changes in the chemical–physical characteristics and circulation of sea water. Dendrophyllia ramea is classified as ‘Vulnerable’ according to the Mediterranean IUCN Red List, and it is listed in the Barcelona Convention (Annex B). Data on the distribution of D. ramea allows us to review the species’ classification and propose that its status be changed to ‘Endangered’.

A mycobacterial disease is associated with the silent mass mortality of the pen shell Pinna nobilis along the Tyrrhenian coastline of Italy

Disease is an increasing threat for marine bivalves worldwide. Recently, a mass mortality event (MME) impacting the bivalve Pinna nobilis was detected across a wide geographical area of the Spanish Mediterranean Sea and linked to a haplosporidian parasite. In 2017–2018, mass mortality events affecting the pen shell Pinna nobilis were recorded in two different regions of Italy, Campania and Sicily, in the Tyrrhenian Sea (Mediterranean Sea). Histopathological and molecular examinations of specimens showed the presence of Haplosporidium sp. in only one specimen in one area. Conversely, in all of the surveyed moribund animals, strong inflammatory lesions at the level of connective tissue surrounding the digestive system and gonads and linked to the presence of intracellular Zhiel-Neelsen-positive bacteria were observed. Molecular analysis of all of the diseased specimens (13) confirmed the presence of a Mycobacterium. Blast analysis of the sequences from all of the areas revealed that they were grouped together with the human mycobacterium M. sherrisii close to the group including M. shigaense, M. lentiflavum and M. simiae. Based on pathological and molecular findings, it is proposed that a mycobacterial disease is associated with the mortality episodes of Pinna nobilis, indicating that, at this time, Haplosporidium sp. is not responsible for these events in Campanian and Sicilian waters.

Water quality assessment of transitional and coastal marine Sicilian waters (Italy): Ecological and epidemiological significance of multiple antimicrobial resistant Enterococcus spp.

The water quality of Sicilian transitional and coastal marine areas was investigated by evaluating the distribution of Enterococcus spp.; as a reference, two sewage samples were also analysed. The epidemiological implications of their presence were considered. Enterococcal strains isolated by culture methods were phenotypically and molecularly identified and their susceptibility to antibiotics tested. High phenotypic variability was detected, with low specific identification for 46% of the isolated strains. E. casseliflavus, isolated from transitional environments only, predominated; in coastal and sewage waters E. faecium prevailed, occurring also in transitional environments, where multiple antibiotic resistances were found. Ampicillin and vancomycin resistant enterococci were isolated exclusively from transitional environments. The dynamics of dissemination of antibiotic resistant enterococci in aquatic environments located across the South-North migration route of many wild birds could be very complex, emphasising the relevance of epidemiological studies on transitional aquatic environments as reservoirs of pathogenic enterococci, as well as on sedentary seagulls and migratory wild birds as carriers and spreaders of antibiotic resistant enterococci.

Habitat suitability modelling for a key small pelagic fish species (Sardinella aurita) in the central Mediterranean sea

The study presents the biomass and spatial distribution of Sardinella aurita in the Libyan, Maltese and southern Sicily waters, estimated during four acoustic surveys in summer 2008 and 2010. Strong differences in terms of both spatial distribution and total biomass between years and areas were found, with higher total biomass in 2010 than in 2008 in both southern and northern areas of the central Mediterranean. Habitat suitability and changes in the spatial dynamics of round sardinella among areas and years are then explored in relation to total biomass variation and environmental factors. The area of presence of S. aurita increased in the Maltese and Sicilian waters in 2010 with respect to 2008, while most of the total biomass observed in the two years occupied the same proportion of the continental shelf in Libyan waters. The link between environmental conditions and S. aurita area of presence and aggregation was investigated by means of generalized additive models (GAM). The application of GAM singled out the key role of depth and temperature in driving higher round sardinella aggregations, as they were able to explain in both years about the 48% of total deviance in the case of strictly positive values. Favourable habitat for round sardinella was found in waters shallower than 60 m depths, with a clear peak around 40 m depth. Favourable temperature values were above 22°C for presence/absence case and above 24°C when GAM was applied on strictly positive values. Overall S. aurita biomass and distribution were discussed in the light of the classical models proposed to describe the fish spatial dynamics in relation to an increase in total biomass.

Recent records of swordfish attacks on harpoon vessels in the Sicilian waters (Mediterranean Sea)

Recent cases of swordfish attacks on harpoon fishing vessels of the Sicilian fleet were examined and the particular behavior adopted by this fish during the approach to fishermen was described.The information was collected in the period between 1999 and 2014 in Sicilian waters (Mediterranean Sea) through interviews with harpoon fishermen and through direct observations during research activities. Additional cases of the attacks from the previous years are also reported. Overall, 29 cases of swordfish aggressive behavior against fishing boats were documented. Swordfish usually attacked when provoked or when wanted to defend its mate and in several cases, it tried to pierce the boat by the bill. Some attacks culminated with a damage to the target, whereas no injuries to humans were recorded.

Different key roles of mesoscale oceanographic structures and ocean bathymetry in shaping larval fish distribution pattern: A case study in Sicilian waters in summer 2009

Fish larvae data collected in year 2009 were used to examine the effects of particular environmental conditions on the structure of larval assemblages in two oligotrophic Mediterranean areas (the Southern Tyrrhenian Sea and the Strait of Sicily). For this purpose, relationships with environmental variables (temperature, salinity and fluorescence), zooplankton biomass, water circulation and bathymetry are discussed. Hydrodynamic conditions resulted very differently between two study areas. The Southern Tyrrhenian Sea was characterized by moderate shallow circulation compared to the Strait of Sicily. In this framework, distribution pattern of larval density in the Tyrrhenian Sea was mainly driven by bathymetry, due to spawning behavior of adult fish. There, results defined four assemblages: two coastal assemblages dominated by pelagic and demersal families and two oceanic assemblages dominated by mesopelagic species more abundant in western offshore and less abundant in eastern offshore. The assemblage variations in the western side was related to the presence of an anti-cyclonic gyre in the northern side of the Gulf of Palermo, while in the eastern side the effect of circulation was not very strong and the environmental conditions rather than the dispersal of species determined the larval fish communities structure. Otherwise in the Strait of Sicily the currents were the main factor governing the concentration and the assemblage structure. In fact, the distribution of larvae was largely consistent with the branch of the Atlantic Ionian Stream (AIS). Moreover, very complex oceanographic structures (two cyclonic circulations in the western part of the study area and one anti-cyclonic circulation in the eastern part) caused the formation of uncommon spatial distribution of larval fish assemblages, only partially linked to bathymetry of the study area. Typically coastal larvae (pelagic families: Engraulidae and Clupeidae) were mostly concentrated in the offshore areas and off Capo Passero, where the presence of a thermo-haline front maintained their position in an area with favourable conditions for larval fish feeding and growth.

Spreading factors of a globally invading coastal copepod

The Mediterranean Sea is one of the areas most affected by alien invasions, which are continuously increasing also due to intense human activities and environmental changes that favor the introduction of species previously unable to colonize the basin. This is the case of the copepods of the genus Pseudodiaptomus, first described in the Indian Ocean and considered one of the most resistant to unfavorable conditions but never recorded in the Mediterranean until 2011 though present in adjacent seas. Pseudodiaptomus marinus, in particular, is common in shallow marine-brackish waters and is one of the species often found in ballast waters and in aquaculture plants. Native of Japan, it has started spreading since 1950s and its populations have established in several harbours, eutrophic inlets and lagoons along the coasts of the Pacific and Indian Oceans. In the last few years, P. marinus has been increasingly reported in European Seas (Mediterranean Sea and North Sea). In this paper, we review the invasion history of this species with a special emphasis on its records in the Mediterranean Sea, and its occurrence and establishment in Sicilian waters. We also compare the biological traits and population dynamics of P. marinus with those of other representative of the genus and discuss about the possible mechanisms of introduction in new environments. Aim of our work is to understand the reasons of successful invasion of P. marinus and the environmental and biological factors that may lead to its further biogeographic expansion.

Distribution of natural populations of the killifish Aphanius fasciatus (Valenciennes, 1821) (Teleostei: Cyprinodontidae) in Italy: past and current status, and future trends

The census of natural populations provides relevant information for both conservation purposes and environmental monitoring. In the present work, natural populations of the killifish Aphanius fasciatus (Teleostei: Cyprinodontidae) were censused in the Italian territory. The historical distribution of the species was reconstructed with the aid of bibliographic material and museal samples, in order to evaluate the extent of changes in its distribution. Three periods (pre-1990s, 1990s, post-1990s) and five habitat types (lagoons/coastal ponds, saltworks, canals, river mouths, inland water bodies) were considered. Overall, we recorded the presence of A. fasciatus in 82 localities, the majority of which are lagoons/ponds. The species showed a widespread decline and sometimes local population extinction, due to habitat degradation and competition with the introduced poeciliid Gambusia holbrooki. With a few exceptions, A. fasciatus is currently extinct in inland waters, being mainly present in coastal brackish-water habitats. The occurrence of stable populations along the central Tyrrhenian, northern Adriatic, Sardinian and Apulian coastal biotopes is confirmed. The populations of Sicilian inland waters, considered extinct, showed recovery capabilities. In northern Tuscany, where the species was also considered extinct, there are also recent records. From a temporal perspective, the present work shows that A. fasciatus experienced population reductions throughout its range in the 1990s, when the species appeared locally extinct, or strongly rarefied, in several localities. Since then, the species recovered in the majority of the native range. However, careful monitoring is needed in order to control the effects of habitat alterations and competition with G. holbrooki on natural populations of A. fasciatus. Given the importance of brackish-water habitats as both biodiversity hotspots and buffer areas against rainfalls and floods, A. fasciatus may be raised to the status of “umbrella species” with regard to these habitats.

Sicilian transitional waters: current status and future development

To appraise the current knowledge of Sicilian transitional waters (TWs), a review was undertaken of the information available on these ecosystems. In detail, a synthesis of the current status is reported, highlighting for each area the ecological features and status, historical data, conservation regime, environmental emergencies and anthropic pressures to which they are subject. The Sicilian TWs reviewed include coastal ponds and lakes, mires and areas with active and nonactive saltworks. Almost all of these ecosystems are affected by several protection regimes because of their high naturalistic value, although current knowledge is limited and fragmented. A few areas have received more attention from the scientific community, whereas others are consistently less studied. The overall picture is one of high heterogeneity in terms of origin, typology, surface, animal and vegetal communities, marine and freshwater exchanges, anthropic pressure and intended use.

Macrophytobenthos and the ecological status of coastal waters around Sicily

This article gives a picture of recent studies on the phytobenthos of Sicily, paying particular attention to research carried out in the last 10–15 years. Twenty new taxa have been described from Sicily, and floristic studies have recorded 823 taxa at the specific and infraspecific levels. Vegetational studies have been used to verify changes that have possibly occurred in Sicilian areas over the last 30 years. Particular attention was also paid to 22 taxa considered to have been introduced into the Mediterranean Sea and which are found along the Sicilian coast. Applied research dealt mainly with management of the territory, promotion of a sustainable development model for the coastal zone, and using macroalgal communities to assess the quality of Sicilian waters. Finally, some suggestions for studies that should be carried out to increase phytobenthic knowledge of Sicilian coastal waters are made.

Ecological characterization and cladocerans, calanoid copepods and large branchiopods of temporary ponds in a Mediterranean island (Sicily, southern Italy)

Temporary waters have been sporadically investigated in Sicily. These environments reflect the climatic features of the Mediterranean area with a winter ponding phase and a more or less prolonged dry period in summer. Their biota, especially those organisms strictly linked to aquatic environments and without any terrestrial life stage, have to exhibit special adaptations to survive the dry phases that are recurrent in such ecosystems. This study included more than 250 water bodies distributed on the whole Sicilian territory and on the small circum-Sicilian islands. This paper represents a first attempt to characterize Sicilian temporary waters from an ecological point of view and is mainly based on some of their limnological features and on the crustacean components of their communities. In particular, the groups which have been taken into consideration are those of cladocerans, calanoid copepods, and large branchiopods (notostracans, anostracans, and spinicaudatans).

The marine Crustacea Decapoda of Sicily (central Mediterranean Sea): A checklist with remarks on their distribution

A checklist of the Crustacea Decapoda of Sicily, based on previously published records and on original data, is presented. The Sicilian waters were divided into three sectors to account for the different habitats present along the northern and western (sector A), eastern (B) and southern (C) coasts, for the sake of a better interpretation of the species distribution. A total of 186 species was recorded between 0 and 800 m depth, 31 of which are reported here for the first time. Sector A hosted 153 species, B 105 species, and C 117 species. The dissimilarities among the habitats present in the shallow waters of the three sectors accounted for the low co‐occurrence of species: 30 species were common to A and C, 13 to A and B, and 2 to B and C. Seventy‐two species co—occurred in the three sectors, recorded mainly in offshore soft bottoms investigated by trawl surveys. The importance of the aid given by such surveys, as well as by stomach contents analysis, in support of faunistic studies is highlighted. Lastly the affinity of the Mediterranean decapod fauna with that of the northeastern Atlantic is briefly discussed.

An Outline Of The Biology of the Squid Illex Coindetii in the Sicilian Channel (Central Mediterranean)

INTRODUCTIONThe genus Illex is likely to constitute a large portion of the annual world ommastrephid squid catches (Roper et al, 1984), even though specific official statistics are difficult to obtain. The broad-tail short-fin squid Illex coindetii is a widespread species ranging from the western to the eastern Atlantic (Roper et al., 1984) and east through the whole Mediterranean Sea (Mangold & Boletzky, 1987). Usually a by-catch of important fisheries, it is caught mainly by trawlers. Although its economic value is lower than that of other squid species (i.e. Loligo spp.), in the Sicilian Channel Illex coindetii may represent a valuable resource due to its abundance.In Italian waters, the available statistics (Cingolani et al., 1986) report that 2680 tonnes of ommastrephid squid were landed in 1982 (0.5% of the total landed catch). The main component of these was landed in Sicily (2183 tonnes), a consistently large part of which was no doubt Illex coindetii (Ragonese & Jereb, 1992). The catches came mainly from southern Sicilian waters (Sicilian Channel) where one of the major Mediterranean landing places is in Mazara del Vallo. Large trawlers (up to 200 gross tonnage) usually carry out long fishing trips (15–20 d), and Illex coindetii is caught mainly by those targeting Parapenaeus longirostris and Merluccius merluccius (Jereb & Ragonese, 1991).