1,720,986 research outputs found
Filling a Gap: a population of Eunicella verrucosa (Pallas, 1766) (Anthozoa, Alcyonacea) in the Tavolara-Punta Coda Cavallo Marine Protected Area (NE Sardinia, Italy)
No full textAmong Mediterranean habitat-forming alcyonaceans, the sea fan Eunicella verrucosa is
known to form dense forests at circalittoral depths, providing seascape complexity and sustaining
a rich associated fauna. Its occurrence in the Tavolara–Punta Coda Cavallo Marine Protected Area
(NE Sardinia) has never been deeply investigated despite this area being well known from a biocoenotic
point of view. This study provides new information on the size of the colonies settled between
35 and 59 m depth on granitic outcrops and represents a contribution to highlighting the hotspot of
megabenthic diversity enclosed in the protected area. The presence of 100 colonies was assessed by
photographic samplings performed between 2015 and 2020, in a small area characterized by peculiar
ecological conditions. The morphometric descriptions and age estimation showed a persistently
isolated population probably derived from a stochastic event of settling of larvae presumably coming
from the Tuscany Archipelago. A richly associated epibiotic community, composed of 18 species/
OTUs, showed how branched bryozoans, particularly Turbicellepora avicularis, and the parasitic
octocoral Alcyonium coralloides, affected the colonies’ branches, suggesting a putative anthropogenic
impact related to fishing activity. This study indicates that proper protection and management strategies
are mandatory for the Marine Protected Area, in order to conserve this unique population and
the whole associated benthic assemblage
Placogorgia coronata first documented record in Italian waters: Use of trawl bycatch to unveil vulnerable deep-sea ecosystems
No full textDespite the pluri-decennial history of bottom trawling monitoring in the Italian Sea, limited attention has been given to the study of cold water corals (CWCs) present in the bycatch. As a result, trawl samples still hold a great potential to reveal information about deep-water biodiversity. The rare Mediterranean CWC species Placogorgia coronata was repeatedly found in the bottom trawl discards of the red shrimp fishery in Santa Margherita Ligure (Ligurian Sea). The supposed rarity of this species is strongly biased by taxonomic problems within the genus as well as by the limited exploration of these deep habitats. Scientific literature as well as remotely operated vehicle surveys highlighted the presence, in the investigated trawled area, of a dead white coral framework, supporting the hypothesis that the CWC studied, probably thriving on coral rubble, occurs here due to the natural protection to trawling offered by the coral matrix. Trawlers, however, may accidentally affect these secondary hard grounds, as demonstrated by the discard content. The long-term monitoring of the catches highlighted a removal rate of up to one colony every two trawling operations; based on the anecdotal fishing effort in this area and the status of the discarded specimens, it is possible to estimate an average catch rate of about 18 live colonies per year per fisherman. The occurrence of rare CWC species with low resilience to fishing disturbance is among the required information for the identification of fishing restriction zones designed to protect deep vulnerable marine ecosystems
Local Conditions Influence the Prokaryotic Communities Associated With the Mesophotic Black Coral Antipathella subpinnata
Full text linkBlack corals are important habitat-forming species in the mesophotic and deep-sea zones of the world’s oceans because of their arborescent colony structure and tendency to form animal forests. Although we have started unraveling the ecology of mesophotic black corals, the importance of the associated microbes to their health has remained unexplored. Here, we provide in-depth assessments of black coral-microbe symbioses by investigating the spatial and temporal stability of these associations, and make comparisons with a sympatric octocoral with similar colony structure. To this end, we collected samples of Antipathella subpinnata colonies from three mesophotic shoals situated along the Ligurian Coast of the Mediterranean Sea (Bordighera, Portofino, Savona) in the spring of 2017. At the Portofino shoal, samples of A. subpinnata and the gorgonian Eunicella cavolini were collected in November 2016 and May 2017. Bacterial communities were profiled using 16S rRNA gene amplicon sequencing. The bacterial community of E. cavolini was consistently dominated by Endozoicomonas. Contrastingly, the black coral microbiome was more diverse, and was primarily composed of numerous Bacteroidetes, Alpha- and Gammaproteobacterial taxa, putatively involved in all steps of the nitrogen and sulfur cycles. Compositional differences in the A. subpinnata microbiome existed between all locations and both time points, and no phylotypes were consistently associated with A. subpinnata. This highlights that local conditions may influence the bacterial community structure and potentially nutrient cycling within the A. subpinnata holobiont. But it also suggests that this coral holobiont possesses a high degree of microbiome flexibility, which may be a mechanism to acclimate to environmental change
The cold-water coral province of the eastern Ligurian Sea (NW Mediterranean Sea): historical and novel evidences
Full text linkSeveral bathyal cold-water coral provinces, characterized by a lush growth of habitat-forming scleractinians, have been recognized in the Mediterranean Sea. However, the search for this biogenic habitat only marginally targeted the Italian coast of the Ligurian Sea (NW Mediterranean basin) despite historical and a few recent local studies in the region reporting the presence of corals. This study used bathymetry maps, side-scan sonar profiles, historical charts, and trawling routes to identify sites that could potentially host coral habitats in the eastern sector of the Ligurian Sea. Remotely operated vehicle video footage from various projects (2015-2021, 20 dives) was then used to characterize four sub-areas (Genoa Plateau, Portofino, Deiva Marina, and Monterosso) where corals were detected between 450 m and 750 m depth. Radiocarbon dating was used to trace back the geological history of the coral structures. A small coral mound, impacted by trawling activities, was found on the Genoa Plateau, while four massive coral structures were found in the other sub-areas, mainly located in a morphologically complex and highly energetic canyon region. High levels of megafaunal biodiversity, including rarely reported alcyonaceans as Placogorgia coronata, were observed together with moderate fishing impact. Overall, the identified coral areas potentially account for 9 km(2) of both subfossil mounds (as old as 13300 years BP), dominated by Desmophyllum pertusum, and living reefs, dominated by Madrepora oculata, the latter representing up to 23% of the substrate coverage. The few living colonies of D. pertusum in the area represent the first documented records for the Ligurian Sea. These data support the presence of a distinct eastern Ligurian cold-water coral province
Massive strandings of Velella velella (Hydrozoa: Anthoathecata: Porpitidae) in the Ligurian Sea (North-western Mediterranean Sea)
No full textVelella velella, the so-called by-the-wind sailor, is a common member of the open-ocean pleustonic fauna, worldwide distributed in tropical and temperate regions. Thanks to their sail protruding above the sea surface, floating polymorphic colonies of this hydrozoan are carried by winds, and tend to aggregate in large swarms, that often get stranded along the shores. Although these events are commonly observed in springtime along the Ligurian coasts (North-western Mediterranean Sea), no quantitative characterization was ever made. The aim of this study was to characterize the stranding events that occurred in spring 2016 along the Ligurian coast, by evaluating the influence of the local sea conditions and by quantifying the abundance of the stranded colonies in each event. Their size-frequency distribution and biomass were examined, and the associated mollusc fauna identified and counted. The magnitude of these episodes was so relevant that, along the Ligurian coasts, the V. velella strandings constitute one of the most important biological deposition of organic matter; nevertheless, the ecological role of these remarkable and stochastic accumulations of chitin along the coast is still unexplored
Optimization of scuba diving activities in a Mediterranean marine protected area based on benthic vulnerability assessment
No full textScuba diving has become an increasingly popular recreational activity, involving approximately 6 million active divers worldwide.The high frequency of diving can impact the benthic communities of marine protected areas (MPAs), possibly jeopardizing the beneficial effects of protection.The Portofino MPA, in the Ligurian Sea, is one of the main scuba diving destinations in Europe, with up to 40,000 dives per year concentrated along 6.5 km of coast.The vulnerability of megabenthic (i.e. animals larger than 5 cm) communities to scuba diving impacts was evaluated at four different depths at all MPA diving spots with close attention to the fragility of all observed species, their frequency in the transects and the inclination and type of substrates.The most vulnerable spots lie below 30-m depth and are characterized by complex coralligenous biocoenoses rich in erect, fragile carbonatic species.The results allowed scuba diving management within the MPA to be optimized. Two main responses have already been put in place: (i) the promotion of a mandatory course for 'Underwater Environmental Supervisors' directed at local divemasters, instructors and owners of diving centres; and (ii) the proposal for the application of conservation measures to scuba diving activities
Fate of lost fishing gears: Experimental evidence of biofouling colonization patterns from the northwestern Mediterranean Sea.
No full textALDFGs (abandoned, lost or otherwise discharged fishing gears) represent a major pollutant in the
world’s oceans, including the Mediterranean Sea, but very little is known about their long-term fate in
the underwater environment. Here we investigate the destiny of ALDFGs in a coralligenous benthic
community by studying the biofouling growing on them at 30 m depth over a three-year period. Results
indicate that ALDFGs are quickly covered by biofouling, reaching maximum values of cover in one year. At
this depth, the biofouling community results highly influenced by light-dependent seasonal cycles and a
general four-steps colonization scheme is tentatively depicted: i) biofouling community is initially
dominated by fast-growing organisms, with algae and hydrozoans settling after two weeks; ii) smallsized
carbonatic organisms (e.g. bryozoans) appear after two months; iii) the same organisms
(including coralline algae) become abundant after five to eight months; iv) conspicuous carbonatic
skeletons (serpulids, bivalves and bryozoans) occur after one year increasing in complexity in the
following months. The biofouling settled on ALDFGs, as well as growth rates of large carbonatic species,
could provide useful information to estimate the age of lost lines and nets in retrieved material and in
situ photo footage complementing the overview of the fishing impact in this specific environment.
Finally, no signs of nylon degradation are reported, suggesting that the prevailing physical conditions and
the biofouling cover extent could alter microplastics release from nylon ALDFGs
Artisanal fishing impact on deep coralligenous animal forests: A Mediterranean case study of marine vulnerability
No full textVulnerable Marine Ecosystems (VMEs) are characterized by prominent biological features susceptible to anthropogenic
disturbances. Following international guidelines, the identification and protection of VMEs require
a detailed documentation regarding both the community structure and the fishing footprint in the area. This
combined information is lacking for the majority of the Mediterranean mesophotic rocky reefs that, similarly to
deep-seabottoms, are known to host valuable animal forests.
A deep coralligenous site exploited by artisanal fishermen in the NW Mediterranean Sea is here used as a
model to assess the vulnerability of animal forests at mesophotic depths and evaluate the sustainability of artisanal
fishing practices, particularly lobster trammel net. The Remotely Operated Vehicle (ROV) footage is used
to document the biodiversity and health status of the megabenthic communities, while discard data are employed
to quantify the entanglement risk, discard rates of fragile species and threats to sea floor integrity.
A multidisciplinary approach is proposed for the assessment of the vulnerability criteria of an EU Special Area
of Conservation, leading to specific management measures, including the delineation of fishing restrictions
Outstanding Aggregation of the Atlantic Brisingid Hymenodiscus coronata (Sars, 1871) (Echinodermata: Asteroidea) in the Strait of Sicily
No full textThe sea star Hymenodiscus coronata is the only Mediterranean representative of the deepsea
order Brisingida. In the North-eastern Atlantic Ocean, this species is known to create dense
aggregations, while, in the Mediterranean basin, it is generally reported as scattered individuals.
Through the analysis of the video footage obtained from an extensive ROV campaign carried out in
the northern Strait of Sicily in 2021, over 2850 specimens were counted. The specimens, observed
between 310 m and 714 m depth, showed a large variability in size and number of arms. It was
noted that 17% of the specimens displayed the peculiar “sail position”, with all the arms extended
vertically in the water column, possibly increasing the filtration rate. Almost the totality of the
individuals was noted on soft bottoms, in accordance with the ecological preferences of the species.
The density of H. coronata in each site varied between 0.01 and 0.81 individuals m−2, with the highest
densities reported in sites characterized by large muddy areas among rocky outcrops and turbulent
hydrodynamic conditions. Although the trawling areas exploited in 2021 did not seem to interfere
with the presence of H. coronata in the study area, a precautionary approach should be assumed to
protect the largest ever reported Mediterranean aggregation of this poorly known species
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