Franco Andaloro

First evidence of presence of plastic debris in stomach of large pelagic fish in the Mediterranean Sea

This study focuses, for the first time, on the presence of plastic debris in the stomach contents of large pelagic fish (Xiphias gladius, Thunnus thynnus and Thunnus alalunga) caught in the Mediterranean Sea between 2012 and 2013. Results highlighted the ingestion of plastics in the 18.2% of samples. The plastics ingested were microplastics (<5mm), mesoplastics (5-25mm) and macroplastics (>25mm). These preliminary results represent an important initial phase in exploring two main ecotoxicological aspects: (a) the assessment of the presence and impact of plastic debris on these large pelagic fish, and (b) the potential effects related to the transfer of contaminants on human health.

Food and feeding habits of pearly razorfish, Xyrichtys novacula (Linnaeus, 1758), in the southern Tyrrhenian Sea: variation by sex and size

We collected pearly razorfish, Xyrichtys novacula (Labridae), from a sandy bottom of Capo d’Orlando (Tyrrhenian Sea) to study their feeding habits. We caught fish by hand-lines and seine nets and identified, counted and weighed food items in their stomachs. We evaluated the importance of the different prey types by calculating the frequency of occurrence, abundance and mass. We used these values to calculate the index of relative importance (IRI) for each taxonomic category and a modified index (MI) which did not incorporate %N into the formula. Gammarideans were dominant food items in terms of %F but showed a very low MI value; the bivalve Acanthocardia tubercolata was the dominant species in terms of %W and MI value. The prey items were mostly benthic organisms belonging to the assemblage of fine, well-sorted sands showing that X. novacula is a benthic feeder. Despite the large number of prey taxa found, few species accounted for most of the prey consumed, indicating specialist feeding, as confirmed by the low value of the Levins’ standardised index. We found significant differences in prey distribution among size classes, with the highest prey diversity recorded in 120–140 mm TL size classes. Correspondence analysis showed a trend of increasing predator size classes among prey items, with small prey, such as copepods and amphipods, in the smallest predator size classes and bigger prey in the larger ones. Prey caught by larger predators differed significantly in weight from those taken by smaller specimens. There was a significant positive correlation of fish length with bivalves, decapods and echinoids, and a negative one with copepods, ostracods, caprellids, gammarideans. There were no significant differences between males and females of overlapping sizes. Juveniles are able to exploit only small, vulnerable prey, while adults take few, large prey, thereby avoiding competition with juveniles.

Resource partitioning among early colonizing Siganus luridus and native herbivorous fish in the Mediterranean: an integrated study based on gut-content analysis and stable isotope signatures

The present study attempts to give timely information on the resource partitioning between the lessepsian migrant Siganus luridus and two ecological native analogues, Sarpa salpa and Sparisoma cretense. Sampling was carried out in concomitance with the first record of Siganus luridus in Linosa and fish were caught simultaneously, allowing direct comparison of diets. Gut-contents analyses provided a snapshot of the feeding habits of the three species: Siganus luridus fed on 34 taxa of benthic algae (mostly represented by Dictyota dichotoma) and a total of 27 taxa was identified in the stomach of Sarpa salpa, with the predominance of Sargassum vulgare. For the first time, a detailed picture of Sparisoma cretense diet was given (N=22 taxa of identified algae) albeit, due to the high percentage of digested food, this species was excluded from gut-content comparisons. A certain resource partitioning between Siganus luridus and Sarpa salpa was resolved on the basis of trophic indices and multivariate analyses, these latter also highlighting a more dispersed diet for Siganus luridus with respect to Sarpa salpa. Isotopic signatures were important towards defining the trophic level of the three species and particularly of Sparisoma cretense, whose gut-contents analysis was only partially informative. The values of δ 15 N confirmed a strictly vegetal diet for Siganus luridus and Sparisoma cretense while Sarpa salpa was significantly more enriched. According to δ 13 C, observed values matched the predicted ones for Siganus luridus and Sarpa salpa while both species presented less enriched δ 15 N values than expected.

Plastic litter in sediments from a marine area likely to become protected (Aeolian Archipelago's islands, Tyrrhenian sea)

This research aims to define for the first time levels and patterns of different litter groups (macro, meso and microplastics) in sediments from a marine area designed for the institution of a new marine protected area (Aeolian Archipelago, Italy). Microplastics resulted the principal group and found in all samples analyzed, with shape and colours variable between different sampling sites. MPs levels measured in this study are similar to values recorded in harbour sites and lower than reported in Adriatic Sea, while macroplastics levels are notably lower than in harbor sites. Sediment grain-size and island extent resulted not significant in determining levels and distribution of plastic debris among islands. In the future, following the establishment of the MPA in the study area, these basic data will be useful to check for potential protective effects on the levels and distribution of plastic debris.

An insight into the status of the striped dolphins, Stenella coeruleoalba , of the southern Tyrrhenian Sea

Drift-nets are known to result in high incidental catches of some cetacean species. Despite a UN moratorium on their use in the high seas and a ban in the Mediterranean by all European Union countries, including Italy (EC Reg. 1239/98), some fisheries continue to operate illegally. In 2002 and 2003 three line-transect surveys were conducted in the southern Tyrrhenian Sea around the Aeolian archipelago. These transects were designed to assess the presence, distribution and population size of cetacean species likely to be affected by accidental captures in this area. Data were only sufficient to estimate abundance for the striped dolphin. The best estimate (and first such estimate for this area) was 4030 individuals (CV=0.30, 95% CI=2239-7253) for May 2003. A rough estimate of striped dolphin by-catch, based on floating carcases, was calculated as 36 by-caught animals over a period of 12 days (CV=0.58, 95% CI=11-113). These results, although approximate, are a cause for concern. Conservation and management implications of the results are discussed.

Feeding habits of the bullet tuna Auxis rochei in the southern Tyrrhenian Sea

A total of 235 bullet tunas ( Auxis rochei ) was caught off the north-eastern coast of Sicily between March 2003 and March 2004 for the purpose of studying their feeding habits. The fish were caught by means of an experimental surface gill-net during fishing surveys carried out on a monthly basis. The stomach contents were analysed and the prey identified, counted and weighed. The importance of the different prey types was assessed utilizing several feeding indices while possible size-related changes of the diet composition were highlighted by means of hierarchical cluster analysis, nMDS and SIMPER analysis. The results of this study showed that the bullet tuna is an epipelagic off-shore predator feeding on whatever abundant resource is available in the environment with a preference for planktonic crustaceans, small cephalopods and fish larvae. Among crustaceans, hyperiidean amphipods were the most important prey, with Anchylomera blossevillei as the dominant species, followed by the euphausiacean Stylocheiron maximum . Among cephalopods, Heteroteuthis dispar was recorded frequently while fish larvae showed high values of all indices. All prey were pelagic organisms. A size-related change in the diet composition was observed, even if it seemed related to the temporal fluctuations of the zooplanktonic assemblage in the environment. The average prey weight per stomach increased significantly in the larger predators which mostly fed on fish larvae belonging to several commercially important demersal and pelagic species.

Feeding ecology of little tunny Euthynnus alletteratus in the central Mediterranean Sea

The feeding habits of Euthynnus alletteratus and its variations compared to predator size in the central Mediterranean Sea were investigated. The stomach contents of 187 specimens were analysed, ranging from 26.8 to 50.3 cm total length, caught by authorized experimental drift-nets. The difference in food items found in the stomachs was evaluated by occurrence of prey frequency, prey weight, and prey abundance; these criteria were used to calculate an index of relative importance. Fish were the dominant food detected according to all numerical indicators examined and were mainly represented by Maurolicus muelleri and larval stages of teleosts. Hyperiid amphipods, dominated by Anchylomera blossevillei and Phrosina semilunata, were well represented in terms of frequency of occurrence. Variations in the diet composition compared to fish size were observed. Comparative analysis performed on prey abundance highlighted a trend of increasing predator size-classes among prey items. The specimens of the smallest sizes ate mainly adult clupeiforms and larvae or other juvenile teleosts. As fish grew, there were increased amounts of adult teleosts, crustaceans (hyperiids and isopods) and cephalopods. Maurolicus muelleri was the most important prey for the largest specimens analysed. Significant differences among size-classes, both in prey abundance and in prey weight, were confirmed by non-parametric multivariate analysis of variance (NP-MANOVA).

Environmental quality assessment of Grand Harbour (Valletta, Maltese Islands): a case study of a busy harbour in the Central Mediterranean Sea

Contamination levels by plastic debris, trace elements and persistent organic pollutants were assessed and related to macrobenthic diversity within soft bottoms of Grand Harbour (Malta, Central Mediterranean). Sediment toxicity was evaluated by ecotoxicological method, deploying Bacteria (Vibrio fischeri), Echinodermata (Paracentrotus lividus) and Crustacea (Corophium orientale). Univariate analysis (Pearson’s test) was used to test relationships between biodiversity indices, pollutants and grain size. A multivariate approach (PERMANOVA) was applied to investigate for any significant differences among sampling stations concerning plastic abundances and to test the relationship between infaunal abundances and pollutant concentrations (the BIOENV test). Significant differences in the plastic abundances were found between sampling stations. The lowest value for Shannon-Wiener biodiversity index was associated to the highest sediment pollution level. Multivariate analyses suggest that MBT and TBT were factors that most influenced macrozoobenthic abundance and biodiversity. The bivalve Corbula gibba and the introduced polychaete Monticellina dorsobranchialis were the most abundant found species

Differences among fish assemblages associated with a nearshore vermetid reef and two other rocky habitats along the shores of Cape Milazzo (northern Sicily, central Mediterranean Sea)

Fish assemblages associated with shallow rocky bottoms along the coast of Cape Milazzo were investigated within three selected habitats, each represented by a different degree of complexity and namely vermetid reef (VR), rocky-algal reef (RR) and boulder and pebbles (BP). The area, located along the northern coast of Sicily (southern Tyrrhenian Sea) was studied by using a non-destructive diver visual census methodology evaluating species composition and abundance. A total of 39 fish taxa belonging to 15 families were recorded over the three habitats investigated. Multivariate and univariate approaches detected significant differences among the three habitats. These differences were either in fish assemblage structure, in the assemblage parameters or in the abundances of some common species. A multidimensional scaling performed on the entire fish density data set showed distinct groupings for the three habitats. The highest values of mean species richness (S), diversity (H′), evenness (J) and density (N) occurred over the more complex habitat, represented by VR, than over rocky-algal reef habitat or BP. Different habitat preferences were evidenced for several fish species. Diplodus sargus , Serranus scriba , Tripterygion tripteronotus , T. delaisi and T. melanurus were significantly more abundant over VR whereas Thalassoma pavo and Symphodus tinca were more abundant both over VR and BP habitats. Statistical comparison did not detect habitat preferences in Symphodus roissali , Oblada melanura , Diplodus vulgaris and Sarpa salpa . As far as the size is concerned, small, medium and large-sized specimens of D. sargus and only large-sized individuals of D. vulgaris were significantly more abundant over the VR habitat side than over the other two. These results suggest that differences in assemblage parameters are related to habitat structure. Greater habitat complexity means greater surface available, thus providing additional resources for adults and juveniles of many species: food, cavities, caves and then new niches, refuges from predation, from artisan fishery nets, as well as resting or mating sites, boosting the total number of individuals and species. The results of this study highlight the importance of VR in sustaining the biodiversity of fish assemblages and emphasize the need for their careful management in an area already proposed as a Site of Community Interest.

Ecological assessment of a heavily human-stressed area in the Gulf of Milazzo, Central Mediterranean Sea: an integrated study of biological, physical and chemical indicators.

Marine environmental disturbance can be assessed directly from physical and chemical parameters, or indirectly by the study of indicator species. In this study, an integrated approach to monitor the Gulf of Milazzo, labeled as a highly contaminated site, is presented. A total of 83 samples were collected from hard and soft bottoms in 2010. In sum, 2739 specimens belonging to 246 taxa, two first records for the Tyrrhenian Sea (Micronephthys stammeri and Nicomache lumbricalis) and three nonindigenous species (Brachidontes pharaonis, Crassostrea gigas and Notomastus aberans) were recorded. Biodiversity and biotic indices and their relationship with sediment parameters and the level of pollutants were assessed to describe faunal assemblage and evaluate environmental quality. Pearson tests evidenced significant negative correlation between polychlorinated biphenyls (PCBs) and specific richness (p<0.10). A comparison of the standard and recorded biotic values showed that M-AMBI seems to be the index more representative of ecological quality status (EcoQ) in the Gulf of Milazzo. No evident signs were highlighted on the complex.