1,720,996 research outputs found
Caratterizzazione dei popolamenti associati agli habitat dominati da Eunicella cavolini (Koch, 1887) e Paramuricea clavata (Risso, 1826) dell’Isola del Giglio, Toscana
No full textThe present work aimed at assessing the structure of coralligenous assemblages dominated by Eunicella cavolini (Koch, 1887) and Paramuricea clavata (Risso, 1826) in the Tyrrhenian Sea. A standardized non-destructive method was applied through photoquadrat sampling. A hierarchical sampling design was used. A total of 64 species belonging to 9 morphological groups were identified and percentage cover of conspicuous morphological groups was calculated. Results suggests that coralligenous communities dominated by E. cavolini and P. clavata constitute highly diverse habitats and they present several similarities to their counterparts in the Aegean Sea
Effects of ocean acidification on phenology and epiphytes of the seagrass Posidonia oceanica at two CO2 vent systems of Ischia (Italy)
Full text linkMorphological features of the seagrass Posidonia oceanica (L.) Delile and its epiphyte community were studied in three acidified stations located in two CO2 vents systems and one control station under normal pH conditions off the island of Ischia (Italy) to highlight the possible effects of ocean acidification. Plant phenology was analyzed every two months for one-year cycle (June 2016-April 2017), while epiphytes were studied in the period of highest development of both the leaf canopy and the epiphytic community (June, August, and October 2016). The shoot density of Posidonia beds in the acidified stations of the studied sites was significantly higher than that in the control area. Significant differences in the mean leaf length according to the pH condition, month, and the interaction of these two factors were observed (PERMANOVA); the mean leaf width differed also among pH conditions and months. We recorded lower leaf lengths and widths in the acidified stations in all the considered months, compared to those in the control station. These differences are consistent with the higher impact of grazing by the herbivorous fish Sarpa salpa observed on the leaves in the acidified stations. However, the overall leaf surface available for epiphytes was similar among stations because of the higher shoot density under ocean acidification conditions. Overall, the composition and structure of the epiphytic community on the Posidonia leaves showed significant differences in relation to acidification: in both acidified sites, all the calcareous forms, both encrusting red algae (Corallinales) and animals (bryozoans, foraminiferans, and spirorbids), disappeared or were strongly reduced, in favor of encrusting or erect fleshy algae, and non-calcifying invertebrates (hydrozoans, tunicates) which dominated the assemblage. Coralline algae are early species in the epiphytic colonization of P. oceanica and therefore their absence can further modify the pattern of leaf colonization by other species. Therefore, the changes found in the epiphyte community in low pH areas could have potential cascading effects on the seagrass trophic network and the functioning of the system
How algae influence sessile marine organisms. The tube worms case of study
No full textTube worms and phytobenthic assemblages in three infralittoral and shallow circalittoral Mediterranean benthic communities developed between 5 and 35 m depth at Punta del Lazzaretto (Giglio Island, Central Thyrrenian sea) were investigated. Despite being three algae-dominated habitats, these displayed different covering both in terms of algal layers and algal morphologies, reflecting different structural
organizations. Twenty-eight serpulid taxa have been reported, increasing both diversity and density values from most photophilic to most sciaphilous habitats. Multivariate analyses showed how algal thalli
and tube worm assemblages were strongly correlated; substrata are influenced both physically and biologically, providing different conditions for tube worm settlement
When scientists and industry technologies mitigate habitat loss. The first bioconstruction relocation in the Mediterranean Sea
Full text linkThe need for habitat recovery in coastal areas, especially those subjected to intensive exploitation, has increased because of significant historical loss and alteration of habitats and, therefore, adverse ecological impacts. The present study defines a stepwise approach to mitigate habitat loss in deep coastal environments, describing the planning, intervention, and monitoring phases following the Trans Adriatic Pipeline (TAP) laying along the Apulian coast
(Adriatic Sea, Italy). Preliminary field activities encompassed morpho-bathymetric data (MBES and SSS), SCUBA and ROV observations to accurately map and characterize the mesophotic reefs built by invertebrates found in the area. The pipeline route interfered with 30 outcrops between 50 and 80 m depth, mostly colonized by 15 taxa/morphological groups. A functional/conservative approach was adopted to recognize the taxa/ morphological groups on which to focus the removal and following relocation activities based on their abundance, conservation status, and functional traits. Saturation divers teams, ROV pilot technicians, and researchers collaborated to minimize the physical impact and the loss of organisms due to the pipeline installation. They relocated a total of 899 living portions (nuclei) from the 30 interfered reefs on the top of the pipeline. The following monitoring activities, carried out after fourteen months since the intervention, revealed a high mean survival rate (88.1%) and slight variations in the structure of the nuclei assemblages. This study represents a paradigmatic case of involvement and support of the private oil and gas sector to mitigate habitat loss in the Mediterranean Sea, and stresses the need for integrated management involving different stakeholders to mitigate the effects of the exploitation of marine resources through ante operam assessment and active restoration actions
Un nuovo strumento per lo studio ed il monitoraggio dei reefs a coralligeno
No full textA novel photo-mosaic sampling method is here proposed and tested on coralligenous reefs. Camera calibration, image acquisition, image processing and image analysis represent the different stages to create large and detailed pictures. The tool allows to increase the sampling area and to gather more information and data with reasonable effort in underwater surveys
Double trouble. Synergy between habitat loss and the spread of the alien species Caulerpa cylindracea (Sonder) in three Mediterranean habitats
Full text linkThe role of habitat degradation on the spread of the alien green alga Caulerpa cylindracea is reported here by comparing observations achieved through a multi-year assessment on three
Mediterraneans habitats, namely Posidonia oceanica meadows, Phyllophora crispa turf, and coralligenous reefs. Due to the peculiarity of the study site, both natural-reference and impacted conditions
were investigated. C. cylindracea occurred in all the studied habitats under impacted conditions. High susceptibility to the invasion characterized impacted P. oceanica, where Caulerpa cover reached 70.0% in summer months. C. cylindracea cover did not differ significantly among conditions in P. crispa turf, where values never exceeded 5.0%. Conversely, the invasive green algae was low in abundance and patchily distributed in coralligenous reefs. Our results confirmed that habitat loss enhances the spread of C. cylindracea, although with different magnitudes among habitats. Dead matte areas of
P. oceanica represented the most vulnerable habitat among those analyzed, whereas coralligenous reefs were less susceptible to the invasion under both the studied conditions
Mediterranean Red Macro Algae Mats as Habitat for High Abundances of Serpulid Polychaetes
Full text linkThe Mediterranean Sea harbors more than 17,000 eukaryotic marine species, with several ecosystems recognized as biodiversity hotspots, such as Posidonia oceanica meadows. Recent research indicates that benthic mats formed by the fleshy red alga Phyllophora crispa are also associated with high species richness. Among key groups found in these mats are sessile polychaetes, which live as epiphytes on the red algae thalli. Knowledge of abundance, species richness, and spatial variation of polychaetes associated with these habitats is still scarce. We carried out a comparative assessment focusing on serpulid polychaetes within samples from P. crispa mats and neighboring P. oceanica meadows at six different sampling sites around Giglio Island (Tyrrhenian Sea, Italy). A total of 17 serpulid taxa were identified. The abundance of serpulids (5665 individuals m−2 of P. crispa mat) were similar to neighboring P. oceanica meadows (2304 individuals m−2 leaves and 5890 individuals m−2 shoots). The number of serpulid taxa was significantly higher in P. crispa mats (average 6.63 ± 1.32 taxa) compared to P. oceanica beds (average 1.56 ± 0.63 and 1.84 ± 1.04 taxa in leaves and shoots, respectively). Within habitat type, there were no significant differences in species richness between sites. The most abundant species found was Josephella marenzelleri (61% of individuals), while Vermiliopsis spp. and Bathyvermilia sp. were exclusively found in P. crispa samples. Our results highlight that P. crispa mats host an exceptional diversity and that these habitats should be included in conservation strategies. Further research should focus on the significance of other important taxonomic groups within these mats and evaluate the distribution of P. crispa in different regions of the Mediterranean Sea
Colonization dynamic on experimental limestone substrata. The role of encrusting epilithics favouring boring polychaetes
No full textPolychaetes inhabit all the marine benthic communities and play a significant role in the degradation of calcareous substrates in marine environment. Colonization dynamics of encrusting epibenthos and polychaete assemblages on limestone experimental substrates were studied over a 3-year period in a Marine Protected Area: the Underwater Archaeological Park of Baiae (central Tyrrhenian Sea). Competitive and encrusting organisms replaced the pioneer species, dominating the epilithic community, and increasing the available surface. Polychaetes increased in species number over time. Several boring specimens of the species Polydora ciliata and Dodecaceria concharum were responsible for the bioerosion of the calcareous material. The former species characterized the early stage of the succession, whereas the latter settled during the late stages, together with the nestler species Lysidice unicornis, whose boring activity has been hypothesized. Four different surface trace morphologies attributable to boring polychaetes are here reported and described. The number of the polychaete boring traces increased according to the surface covered by ascidians, barnacles, and bryozoans. The present work provides evidence regarding positive interactions between encrusting epibenthic organisms and endolithic worms
Impact and colonization dynamics of the bivalve Rocellaria dubia on limestone experimental panels in the submerged Roman city of Baiae (Naples, Italy)
No full textThe present study describes the role of the bivalve Rocellaria dubia Pennant, 1777 in the bioerosion process of submerged limestone artificial panels. The research was carried out in the central Mediterranean
sea, in the Underwater Archaeological Park of Baiae (Naples, Italy). During the three year experimental period, the panels were submerged at 5 m depth and sequentially removed after 12, 24 and 36 months. R. dubia boreholes strongly affected stone material. The rate of bioerosion increased over time. After 36 months settlement still occurred with hundreds of boreholes and the shells were up to 13 mm in length. The results obtained concerning the impact of R. dubia on the experimental panels help to evaluate the bioerosive role of this species on submerged calcareous archaeological structures
Scuba diving damage on coralligenous builders. Bryozoan species as an indicator of stress
No full textThe effects of scuba diving activities on coralligenous concretions builders in the Mediterranean Sea are reported for a non-marine protected area (non-MPA). Five erect bryozoan species, which are particularly vulnerable due to their fragile structure, were investigated: Adeonella calveti, Myriapora truncata, Pentapora fascialis, Reteporella grimaldii, and Smittina cervicornis. These species were sampled at frequently and rarely visited diving sites to the maximum depths reachable with the most common recreational diving certifications (i.e., 40 m). To do this, a non-destructive photographic sampling technique was used to minimize any impact on the benthic communities. For each sample, the number of colonies, their width, coverage, type of injury and degree of exposure were quantified using image analysis software. The number of species differed between the frequently and rarely visited diving sites, and frequently visited sites had significantly lower number of colonies and reduced colony width. Species-specific response to stress was associated with colony morphology and skeleton rigidity. Both the type of injury and colony position within the coralligenous habitat were affected by the presence of scuba divers. A linear model was proposed to analyse the response of bryozoans to scuba diving pressure. The results reported here suggest that P. fascialis and R. grimaldii could serve as robust species indicators of diving stress
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