Passive acoustic monitoring (PAM) of the brown meagre Sciaena umbra was conducted in a northern Adriatic Sea mussel farm. The level of acoustic activity was found to be constantly high from June to August before declining sharply in September and there was significantly higher acoustic activity in the structured habitats within the mussel farm than in the bare sandy bottom outside the farm. Results are discussed in the context of the use of this species as an indicator species of artificial rocky habitats along the Mediterranean coastal environments.

During the summer of 2015, four Passive Acoustic Monitoring (PAM)surveys were carried out over a\ud mussel farm in the Venetian (Italy) littoral zone at night-time hours. A qualitative and quantitative\ud analysis of the soundscape was carried out. The high frequencies component of the soundscape (i.e.\ud above 2 kHz) was dominated by snapping shrimps sounds, while the low frequency component (i.e.\ud below 2 kHz) was characterized by fish vocalization, mainly emitted by Sciaena umbra (Sciaenidae),\ud with less frequent occurrences emitted by Gobidae spp. S. umbra highest vocal activity was recorded\ud from June to August inside the mussel farm. The low frequency component of the soundscape was\ud dominated by boat noise; in particular, low frequency noise (i.e. below 4 kHz) emitted by commercial\ud ships and passenger cruises. The Acoustic Complexity Index (ACI) was found to increase concurrently\ud with the number of S. umbra vocalizations: ACI highest values corresponded with S. umbra chorus\ud recorded during July. The results of this study suggest that the mussel farm may function as a Fishery\ud Aggregated Device (FAD), where fish might utilize it for different ecosystem services. Despite this,\ud man-made noise was present in most of the acoustic samples, suggesting a potential impact on the local\ud fauna

Artisanal fisheries represents an important source of employment and income for many Mediterranean coastal communities, as well as an important cultural and traditional identity factor at a regional level. However, despite its importance, it is generally under-studied, in both ecological and socio-economic terms, so hampering the chance of developing sustainable and integrated management measures. At present, on the West coast of the Adriatic Sea, within the three-mile area, artisanal fisheries and hydraulic dredging are the only approved commercial fishing activities. This study confirmed the importance of the artisanal fisheries in this area, representing a multitarget and multigear activity. Despite the 39 exploited species, however, we found high vulnerability both for species (76% of total catches depend upon only three species-cuttlefish, mantis shrimp, and sole) and thermal affinity groups (cold and temperate species contributed to the entire catches). Furthermore, our data showed that fishing effort and CPUE values were greater than those reported at the regional level, and also indicated that the discard rate was lower than in other Adriatic areas. Regarding ecological effects, the two trophodynamic indicators that we applied showed a sustainable situation, but scenarios of possible changes in environmental or fishing effort conditions highlighted the proximity of the stock to the unsustainability threshold. Our findings suggest the need for an adequate management strategy to cope with possible future changes in population boundaries and conditions

The marine recreational fishing (MRF) represents one of the most popular activities along the coasts of numerous countries around the world, in particular in the Mediterranean Sea. Despite the evidences of potential effects on the marine biodiversity and commercially exploited stocks, a sound information base and adequate management plans are still lacking, both at the national and basin level. An analysis of the MRF on the West coasts of the Adriatic Sea was carried out, in 2014, by using a standardized questionnaires approach, aiming to describe the state of the art and to preliminarily assess catches, in comparison with the commercial ones, at the regional scale. Gilt-headed seabream, European seabass, cuttlefish, squid and Atlantic bluefin tuna resulted the anglers' preferred species, even if the top five in term of caught biomass were bluefin tuna, seabream, cuttlefish, common dolphinfish and little tunny, in the order (accounting up to 60% of total catches). The exploitation level resulted to be significant, as confirmed by the comparison with commercial fisheries, being the MRF captures 30% or 45% of the artisanal fishery in the same area, with some species, such as bluefish, bonito, pandora and picarel, showing larger values. The preliminary assessment of ecological effects, highlighted that the exploitation use about 10%-16% of energy fixed by the primary production (Primary Production Required to sustain fishery), but the ecosystem effects are still sustainable (Lindex and probability to be sustainable fished). However, combining catches by MRF with those by small scale fishery completely changes the situation, showing an unsustainable condition, suggesting the need for taking into the account also MRF in the future management planning for the Adriatic coastal area

Abstract. This work presents the result of a study carried out in the north-western Adriatic Sea, by combining two different types of biogeochemical models with field sampling efforts. A longline mussel farm was taken as a local source of perturbation to the natural particulate organic carbon (POC) downward flux. This flux was first quantified by means of a pelagic model of POC deposition coupled to sediment trap data, and its effects on sediment bioirrigation capacity and organic matter (OM) degradation pathways were investigated constraining an early diagenesis model by using original data collected in sediment porewater. The measurements were performed at stations located inside and outside the area affected by mussel farm deposition. Model-predicted POC fluxes showed marked spatial and temporal variability, which was mostly associated with the dynamics of the farming cycle. Sediment trap data at the two sampled stations (inside and outside of the mussel farm) showed average POC background flux of 20.0-24.2 mmol C m −2 d −1 . The difference of organic carbon (OC) fluxes between the two stations was in agreement with model results, ranging between 3.3 and 14.2 mmol C m −2 d −1 , and was primarily associated with mussel physiological conditions. Although restricted, these changes in POC fluxes induced visible effects on sediment biogeochemistry. Observed oxygen microprofiles presented a 50 % decrease in oxygen penetration depth (from 2.3 to 1.4 mm), accompanied by an increase in the O 2 influx at the station below the mussel farm (19-31 versus 10-12 mmol O 2 m −2 d −1 ) characterised by higher POC flux. Dissolved inorganic carbon (DIC) and NH + 4 concentrations showed similar behaviour, with a more evident effect of bioirrigation underneath the farm. This was confirmed through constraining the early diagenesis model, of which calibration leads to an estimation of enhanced and shallower bioirrigation underneath the farm: bioirrigation rates of 40 yr −1 and irrigation depth of 15 cm were estimated inside the shellfish deposition footprint versus 20 yr −1 and 20 cm outside. These findings were confirmed by independent data on macrofauna composition collected at the study site. Early diagenesis model results indicated a larger organic matter mineralisation below the mussel farm (11.1 versus 18.7 mmol m −2 d −1 ), characterised by similar proportions between oxic and anoxic degradation rates at the two stations, with an increase in the absolute values of oxygen consumed by OM degradation and reduced substances re-oxidation underneath the mussel farm.

No abstract

This work presents the result of a study carried out in the north-western Adriatic Sea, by combining two different types of biogeochemical models with field sampling efforts. A longline mussel farm was taken as a local source of perturbation to the natural POC downward flux. This flux was first quantified by means of a pelagic model of POC deposition coupled to sediment traps data, and its effects on sediment bioirrigation capacity and OM degradation pathways were investigated by constraining an early diagenesis model, linked to new data in sediment porewaters. The measurements 15 were performed at stations located inside and outside the area affected by mussel farm deposition. Model-predicted POC fluxes showed marked spatial and temporal variability, which were mostly associated with the dynamics of the farming cycle. Sediment traps data at the two sampled stations (in and out of the mussel farm) showed average POC background flux of 20.0-24.2 mmol C m -2 d -1 . The difference of OC fluxes between the two stations was in agreement with model results, ranging between 3.3 and 14.2 mmol C m -2 d -1 , and primarily associated with mussel physiological conditions. Although 20 restricted, these changes in POC fluxes induced visible effects on sediment biogeochemistry. Observed oxygen microprofiles presented a 50 % decrease in oxygen penetration depth (from 2.3 to 1.4 mm), accompanied by an increase in the O 2 influx at the station below the mussel farm (19-31 versus 10-12 mmol O 2 m -2 d -1 ) characterized by higher POC flux. DIC and NH 4 + concentrations had similar behavior, with a more evident effect of bioirrigation underneath the farm. This was confirmed through constraining the early diagenesis model, which calibration leads to an estimation of enhanced and shallower 25 bioirrigation underneath the farm: bioirrigation rates of 40 y -1 and irrigation depth of 15 cm were estimated inside the shellfish deposition footprint versus 20 y -1 and 20 cm outside. These findings were confirmed by independent data on macrofauna composition collected at the study site. Early diagenesis model results indicated a larger organic matter mineralization below the mussel farm (11.1 versus 18.7 mmol m -2 d -1 ), characterized by similar proportions between oxic and anoxic degradation pathways at the two stations, with an increase in the absolute values of oxygen consumed by OM 30 degradation and reduced substances re-oxidation underneath the mussel farm.

No abstract