Fish assemblages inhabiting a complex of south Tyrrhenian seamounts and banks were characterized using a remotely operated vehicle (ROV). Fish distribution was assessed through surveying 15 ROV ...transects. Video segments of each transect were split into two bathymetric ranges, above and below 200 m depth. In total 28 fish taxa belonging to 22 families were recorded. The number of species observed at the Marettimo Banks and the Aceste Seamount was higher compared with the Tiberio and Scuso Seamounts. The number of species recorded in the shallow part (<200 m depth) of the Marettimo Banks and the Aceste Seamount was higher than in the deeper zone (>200 m). Assemblages were numerically dominated by Anthias anthias, Callanthias ruber and Helicolenus dactylopterus. The occurrence of some elasmobranchs of conservation concern, such as Squatina aculeata, Hexanchus griseus, Squalus blainville and Galeus melastomus, was noteworthy. Differences in fish assemblage composition were observed between the Aceste Seamount and the other sites and especially between the two bathymetric ranges. The fish distribution pattern showed significant relationships with bottom slope and some substrate types. A large occurrence of lost fishing gear characterized the sites closest to the coast (the Marettimo Banks and the Scuso Seamount), providing, along with scanty observations of commercially important fishes, evidence of heavy fishing activities. The adoption of conservation and management actions in the investigated seamounts and banks, such as their inclusion in the Natura 2000 network, would be very helpful to protect some threatened elasmobranchs and restore valuable deep-sea habitats.
Every 6 years, the European Commission requires Member States to report on their progress in implementing the Habitats Directive through a process involving the assessment of the conservation status ...(CS) of the Directive’s species and habitats. The results of the marine species assessment undertaken by Italy in the fourth report (2013–2018) are presented and discussed. Twenty-seven species of vertebrates (14 mammals and 5 sea turtles), invertebrates (1 echinoderm, 1 crustacean decapod, 3 molluscs and 1 cnidarian) and algae (2 rhodophytes) were examined through the analysis of different parameters. The distribution pattern of the investigated species was very heterogeneous, ranging from wide, in highly mobile and migratory species (e.g.
Stenella coeruleoalba
and
Caretta caretta
), to narrow or extremely narrow in some rare species (e.g.
Patella ferruginea
and
Monachus monachus
). Data from aerial surveys provided reliable estimates of population size for one sea turtle and three cetacean species. The absence of adequate data time series hampered the evaluation of temporal trends of the species’ evaluation parameters. Human-induced pressures were recognised as the most relevant drivers influencing the CS of all the species. The amount of marine species currently considered in favourable CS increased from 12.5 to 38.9% compared to the 2007–2012 reporting cycle. However, almost 40% of species are still classified as unknown and three species (
M. monachus
,
Pinna nobilis
and
Scyllarides latus
) are considered in an unfavourable (inadequate or bad) CS, stressing the need of implementing long-term monitoring programs coordinated at regional or sub-regional scales to inform management and conservation measures.
Identification of the factors influencing the distribution of vulnerable species can be useful for predicting their occurrence at a local to regional scale and for identifying the most suitable ...measures of management and conservation. We used generalized additive models to assess the effects of spatiotemporal, environmental, and operational factors on the catches of two myliobatids: the Common Eagle Ray Myliobatis aquila and the Bull Ray Pteromylaeus bovinus. Fishing data were collected from commercial midwater trawlers operating in the north-central Adriatic Sea during 2006–2013. Presence/absence and abundance (CPUE) data were modeled separately, and eachmodel was then validated by using a test data set. The presence/absence and abundance of Common Eagle Rays and Bull Rays were mostly influenced by spatial (haul location) and temporal predictors. The major occurrences of Common Eagle Rays and Bull Rays were observed in the upper Adriatic Sea between late spring and early autumn. During winter, a southward shift in the catch was recorded for both species. In accordance with a significant effect of depth, Common Eagle Rays were more likely to be caught in hauls conducted between 10- and 60-m depths. The CPUEs of Common Eagle Rays and Bull Rays declined significantly with haul duration and net vertical opening. The validation procedure indicated that the predictive accuracy of the models was rather good. Giving new insight into the ecological requirements of Common Eagle Rays and Bull Rays, the results of this studymay contribute to the development of conservation strategies and can be used to direct future monitoring and research programs.
The effects of sewage outfalls on subtidal fish assemblages were studied along the NW coasts of Malta (Sicily channel, Mediterranean Sea) by means of underwater visual census. The presence of two ...spatially distinct outfalls discharging untreated wastewaters allowed to use a balanced symmetrical after control/impact (ACI) design that consisted of two putatively impacted locations and two controls, with four sites nested in each location. Surveys were performed in 2006 at two random dates. The study highlighted significant changes at both assemblage and individual species levels. Fish assemblages structures were different between controls and sewages, where total abundance of fish were higher. The responses of individual species to sewage pollution were mostly related to an anomalous increase of two small opportunistic species i.e.
Gobius bucchichii and
Parablennius rouxi and to a decrease of species of the genus
Symphodus, particularly
S. roissali and
S. ocellatus. Moreover in correspondence of the outfalls, significant changes of the fish size distribution were detected for several species. These results support the use of fish assemblages as biological indicators for marine coastal waters and demonstrated the possibility to obtain sharp signals of environmental impact from some individual fish species.
Seven demersal shark species belonging to six families, obtained from the southern Mediterranean Sea, were selected as representative of different putative swimming modes, inhabited depths and ...trophic levels. Caudal fin morphometrics (caudal fin span, area and aspect ratio), hepatosomatic index and muscular-skeletal amount per unit length were estimated and compared within and among species by means of both parametric and non-parametric multivariate and univariate statistical procedures. Intra-specific variation was related to size and, for one species only, also to sex. Two inter-specific patterns of variation were observed: the first pattern was interpreted as a swimming ability gradient between slow benthic and more pelagic species, as a function of caudal morphometry and body characteristics; the second pattern is related to the depth the species inhabit and/or their trophic level. These two hypotheses were tested with the current data and literature information, and discussed in the context of shark swimming modes, habit and environment. Based on observed differences in caudal fin morphometrics, liver and muscular masses, this paper is the first to provide a quantitative and comparative dataset for demersal sharks as a group, and attempts to describe sample variability as a function of expected swimming ability and occupied niche (depth inhabited and/or trophic level).
A pilot experiment of stock enhancement based on the release of hatchery- reared juveniles of dusky grouper, Epinephelus marginatus, was carried out at two artificial reefs located 0.9 km offshore ...the south-western Sicilian coast (Central Mediterranean). The fish assemblages inhabiting the reefs were characterized using underwater visual census (UVC) surveys. Despite some differences in fish species richness, diversity and abundance, both artificial reefs provide suitable feeding resources and shelter opportunities for the settlement of dusky grouper juveniles. A total of 95 dusky grouper juveniles, which were 3 and 4 years old, were released. No stress-related effects on fish swimming or behaviour were observed during the step by step transportation to the sea-bottom at 20 m depth. After release, several groupers showed very low reactivity; freezing and schooling were the most common behaviours. The sighting rate after one month of UVC surveys was 15.7% and 20% at the two artificial reefs. No effect of fish size at release on grouper survival was observed. Some groupers were not recorded on the pyramid of release but elsewhere in the same artificial reef, which demonstrated their ability to move around the reef. The extent of dispersal of the released juveniles largely exceeded the area encompassed by the reefs, which was shown by recaptures of tagged groupers by local fishermen up to 13 km from the release site. This result provides a first insight into the potential of stock enhancement of hatchery reared dusky grouper juveniles for marine ranching and conservation purposes.
A photographic seabed survey conducted off the Antarctic Peninsula region provided the opportunity to study spatial patterns, abundance and behaviour of the notothenioid benthic fish fauna. Overall, ...a total of 12,715 images taken with the Ocean Floor Observation System (OFOS) along 26 transects in three ecoregions (Joinville Island, Bransfield Strait and Drake Passage) were analysed. The fish fauna consisted of at least 34 species belonging to four families of both low-Antarctic and high-Antarctic origin. Nototheniids showed the highest relative abundance and species richness, followed by channichthyids, bathydraconids and artedidraconids. Direct in-situ observations in OFOS seabed images allowed descriptions of fish behaviour, such as aggregation of individuals (
Notothenia coriiceps
), specific body postures (
Cygnodraco mawsoni
and
Cryodraco antarcticus
) and parental care (
Chaenodraco wilsoni
,
Chionodraco rastrospinosus
,
Pagetopsis macropterus
and
Trematomus hansoni
). Fish density and species richness was primarily correlated with the occurrence of bryozoans, ascidians, and large cup-shaped sponges, providing a three-dimensional habitat suitable for fish settling, foraging, breeding and refuge from predators. Fish diversity was higher (a) off Joinville Island and in Bransfield Strait than in Drake Passage, where almost exclusively low-Antarctic species were recorded, and (b) between 100 and 600 m than at greater depths. Overall, the benthic fish fauna off the northern Antarctic Peninsula is zoogeographically composite and widespread, with well-structured spatial partitioning.
•Scleractinian CWCs were discovered through ROV imaging in the southern Tyrrhenian Sea.•Healthy coral patches were observed on a seamount and bank at depths of 240–310 m.•Sparse and dense coral ...colonies were found dwelling on rocky outcrops and on a wreck.•Longline fishing activities have direct and significant impacts on CWC communities.•The establishment of an offshore Natura 2000 site (Habitat 1170) is proposed.
Scleractinian cold-water corals (CWCs) are among the main habitat engineers of the deep Mediterranean Sea, hosting a high diversity of species and playing a significant ecological role. In the last two decades, many new living scleractinian CWC sites throughout the Mediterranean Basin have been recorded and their distribution has been updated. In the summer of 2018, new scleractinian CWC assemblages were discovered by means of remotely operated vehicle (ROV) and multibeam echosounder (MBES) surveys on the Aceste–Tiberio seamount and Marettimo bank in the southern Tyrrhenian Sea, at depths ranging from 240 to 310 m. In the explored areas, megabenthic communities were dominated by habitat-forming species, some of which have never been reported before on these submarine structures. Healthy patches of Madrepora oculata and Desmophyllum pertusum, together with the solitary coral D. dianthus, were found on rocky pinnacles between inclined silted bottoms, as well as on a wreck. Deep-water fishing activities, mainly longline fishing, negatively affected these communities, particularly coral species. The discovery of these new sites adds new knowledge about the distribution of scleractinian CWCs in the Mediterranean Sea. Moreover, the documented negative effect of fishing activities on CWC species further stresses the need for urgent and specific conservation measures. In this regard, the co-occurrence of several long-lived, slow-growing, and vulnerable species on these seamounts and banks supports the establishment of specific marine protected areas i.e., offshore Natura 2000 sites, in accordance with the Habitats Directive (92/43/EEC) - Habitat 1170 - Reefs.
Every 6 years, the European Commission requires Member States to report on their progress in implementing the Habitats Directive through a process involving the assessment of the conservation status ...(CS) of the Directive's species and habitats. The results of the marine species assessment undertaken by Italy in the fourth report (2013-2018) are presented and discussed. Twenty-seven species of vertebrates (14 mammals and 5 sea turtles), invertebrates (1 echinoderm, 1 crustacean decapod, 3 molluscs and 1 cnidarian) and algae (2 rhodophytes) were examined through the analysis of different parameters. The distribution pattern of the investigated species was very heterogeneous, ranging from wide, in highly mobile and migratory species (e.g. Stenella coeruleoalba and Caretta caretta), to narrow or extremely narrow in some rare species (e.g. Patella ferruginea and Monachus monachus). Data from aerial surveys provided reliable estimates of population size for one sea turtle and three cetacean species. The absence of adequate data time series hampered the evaluation of temporal trends of the species' evaluation parameters. Human-induced pressures were recognised as the most relevant drivers influencing the CS of all the species. The amount of marine species currently considered in favourable CS increased from 12.5 to 38.9% compared to the 2007-2012 reporting cycle. However, almost 40% of species are still classified as unknown and three species (M. monachus, Pinna nobilis and Scyllarides latus) are considered in an unfavourable (inadequate or bad) CS, stressing the need of implementing long-term monitoring programs coordinated at regional or sub-regional scales to inform management and conservation measures.
PDF
