Pelagic cephalopods of the central Mediterranean Sea determined by the analysis of the stomach content of large fish predators

The pelagic cephalopod fauna of the central Mediterranean Sea was investigated through stomach content analyses of large fish predators. A total of 124 Xiphias gladius, 22 Thunnus thynnus, 100 Thunnus alalunga, and 25 Tetrapturus belone were analyzed. Overall, 3,096 cephalopods belonging to 23 species and 16 families were identified. The cephalopod fauna in the study area is dominated by Sepiolidae, Ommastrephidae, and Onychoteuthidae. The sepiolid Heteroteuthis dispar was the most abundant species (n = 1,402) while the ommastrephid Todarodes sagittatus showed the highest biomass. They can be considered key-species in the pelagic food web of the study area. The neutrally buoyant Histioteuthis bonnellii, H. reversa, and Chiroteuthis veranyi seem to characterize the deeper water layers. Given the difficulty in sampling pelagic cephalopods, the presence of cephalopod beaks in the stomach of predators represents a fundamental tool to assess the biodiversity and the ecological importance of these taxa in the marine ecosystem

Molecular identity of the non-indigenous Cassiopea sp. from Palermo Harbour (central Mediterranean Sea)

The upside-down jellyfish Cassiopea is a benthic scyphozoan, considered a non-indigenous invasive species in the Mediterranean, forming large blooms in eutrophic areas. Taxonomy of the genus Cassiopea is extremely difficult because morphological/meristic characters used are variable within the same species, overlapping among different species, and cryptic species have been identified by molecular markers; nine Cassiopea species are recognized on the basis of molecular study. Mediterranean records of Cassiopea have been ascribed to andromeda species on the basis of a hypothesized invasion pathway from the Suez Canal. In the current study, an analysis of the main morphological characters of the sampled Cassiopea jellyfish from Palermo (Tyrrhenian Sea) was carried out and subsequently, molecular analyses were performed by using COI barcode in order to identify the species. Molecular data were compared with published information in GenBank. Morphological characters were highly variable, but molecular analyses confirmed that Mediterranean Cassiopea specimens belong to andromeda species. Moreover, high values of sequence divergence were found between Mediterranean Cassiopea and the other C. andromeda from the Red Sea, Hawaii and Florida. These results lead to a discussion of possible explanations linked to life history features of the species. Two different explanations are proposed; the first is that Mediterranean C. andromeda, finding a suitable ecological niche good for colonization and proliferation, could have been isolated in Palermo Harbour. The second considers the possibility of multiple introduction events by human transport as demonstrated for other non-indigenous jellyfish; in this case Cassiopea genetic differences increased in the invaded area

Using local ecological knowledge to search for non-native species in Natura 2000 sites in the central Mediterranean sea : an approach to identify new arrivals and hotspot areas

The management of biological invasions is among the most urgent of global challenges and requires a significant monitoring effort to obtain the information needed to take the appropriate decisions. To complement standard monitoring, citizen science is increasingly being used. Within citizen science, the approach of collecting and investigating Local Ecological Knowledge (LEK) proved to be useful in the monitoring of non-native species. A LEK survey was carried out in 10 Sicilian and Maltese Natura 2000 sites in order to help in the early detection of non-native species. The survey was addressed to local fishers and SCUBA divers in order to investigate the occurrence of 24 selected marine non-native species and to identify potential hotspot areas of invasion through the use of six indicators: the occurrence of newly introduced nonindigenous species, the cumulative impacts of invasive alien species (CIMPAL) and the relative importance of species on the cumulative impacts (D1, D2, D3, and D4). The respondents confirmed the presence of 22 species since the year 2000 and reported 10 new ones registered in the investigated areas. The highest CIMPAL value was observed in two Sicilian Natura 2000 sites (ITA090028 and ITA040014) and the lowest on the western coast of Malta (MT0000101, MT0000102, MT0000103, and MT0000104) The four top-priority species according to indicators D1–D4 were Caulerpa cylindracea, C. taxifolia, Siganus luridus and S. rivulatus. The study produced a valid and useful scientific output to suggest and address management strategies to monitor the establishment of the non-native species.peer-reviewe

The Blue Swimming Crab Portunus segnis in the Mediterranean Sea: Invasion Paths, Impacts and Management Measures

Invasive alien species represent one of the main environmental emergencies and are considered by the scientific community as being among the leading causes of biodiversity loss on a global scale. Therefore, detecting their pathways, hotspot areas and invasion trends becomes extremely important also for management purposes. A systematic review on presence of Portunus segnis in the Suez Canal and Mediterranean Sea was carried out in order to study the invasion paths from its entry from the Red Sea into the Suez Canal (1886) until recently (2021) through ecological indicators elaborated with GIS spatial–temporal statistics. Arrival, establishment and expansion phases and areas of P. segnis in the Mediterranean were identified. Settlement areas were detected along the Suez Canal as well as in the Levantine Sea, western Ionian Sea and Tunisian plateau ecoregions. Since 2015 a persistent area has formed in Tunisia from where the species is spreading northward and eastward. The study provides an insight on the impact of P. segnis on biodiversity and ecosystem services and proposes a series of desirable management actions to mitigate the expansion of its population. Following the 8Rs model that introduces the rules to mitigate non–indigenous species pollution, six of them (Recognize, Reduce, Replace, Reuse, Remove, and Regulate) have been identified as applicable and are discussed

Species and habitats of conservation interest in the Ecologically and Biologically Significant Area of the Strait of Sicily: a contribution towards the creation of a Specially Protected Area of Mediterranean Importance

In 2015, the Strait of Sicily, which includes several banks, was candidate as a future Specially Protected Area of Mediterranean Importance (SPAMI) by the Contracting Parties of the Barcelona Convention. In this context, the present study aims to provide the first biological and ecological characterisation of this poorly known area, focusing on habitats and species of conservation concern. Surveys were carried through a remotely operated vehicle (ROV) and allowed the identification of 19 habitat types, mostly considered of priority interest by the SPA/BD Protocol of the Barcelona Convention. A total of 269 taxa were also identified, mostly Porifera, Cnidaria and Pisces, among which 115 species are of conservation concern according to the IUCN (IUCN) Red Lists, the Habitats Directive, the Bern Convention, the SPA/BD Protocol and CITES. ROV surveys allowed some interesting observations on poorly known species and habitats. Results underlined that remarkable discrepancies in species conservation status assessment exist between the several lists of protected species considered. The IUCN Red Lists, although not legally binding for European States, are the most complete, but, in spite of this, the conservation policies in the EU are largely focused on the Habitats Directive, which is really not exhaustive. An exhaustive and legally binding instrument to protect species of conservation concern at European scale is highly recommended. Acquired results could be useful for the delimitation of a future SPAMI or a network of Marine Protected Areas (including the investigated banks) and the identification of zones within them suitable for different area-based management measures

Snapshot of the Distribution and Biology of Alien Jellyfish Cassiopea andromeda (Forsskål, 1775) in a Mediterranean Touristic Harbour

Harbors are hotspots for the introduction of alien species, and, usually, investigations on their host populations help fill the knowledge gap in their pathways of invasion and in their impacts on marine biodiversity and ecosystems. In 2014, the upside-down alien jellyfish Cassiopea andromeda invaded a Mediterranean touristic harbor (“Cala”), and its abundance has since increased over time. In the present study, the distribution and trophic behavior of C. andromeda in Cala were investigated for the years 2017–2018 through visual sampling, and GIS-based statistical and stable isotope analyses. Since Cala is a hard-to-reach area (with many anchor cables and boats), Megabenthos Underwater Video was used to count the number and estimate the size of jellyfishes. The variations in size throughout the study period suggest that the population of C. andromeda is quite established in Cala at depths lower than 7.5 m. The ranges of the environmental parameters recorded (temperature, salinity, and transparency) were consistent with the ideal conditions for maintaining a Cassiopea population, but they did not seem to influence aggregation. Additionally, the carbon and nitrogen isotopic signatures studied highlight the mixotrophic behavior of this species. These preliminary results confirm the capacity of C. andromeda to live and reproduce in heavily anthropized areas

Multidimensional Scaling (MDS) of the composition of fish assemblages among different degrees of habitat complexity.

<p>Circle = low complexity; triangle = medium complexity; rhombus = high complexity.</p

Multidimensional Scaling (MDS) of the composition of fish assemblages among different depth ranges.

<p>Triangle = 0–50 m; square = 51–100 m; rhombus = 101–500 m; circle = 151–200 m.</p