Innovative Vibrating Hydraulic Dredge for Striped Venus (Chamelea gallina) Fishing

This work proposes the experimentation of an innovative hydraulic dredge for clam fishing (Chamelea gallina) in the Adriatic Sea (Italy). This innovative gear aimed at increasing the selectivity of the typical hydraulic dredge used currently, while at the same reducing the impact on benthos through the conception, installation, and experimentation of innovative technological solutions, consisting mainly of a vibrating bottom panel on the dredge and a “warning device” on the dredge mouth. Comparative experiments of the traditional vs. the modified gear, employing two boats fishing in parallel on the northern coast of Abruzzi (Adriatic Sea) and contrasting the catch with both paired comparisons and through modelling, showed that the innovative hydraulic dredge retains fewer undersize clams while yielding similar amounts of commercial product, moreover of higher quality; at the same time, it takes on board less discard, and catches significantly less vagile fauna. In short, the innovative gear is gaining five times over a list of six parameters considered as positive and/or advantageous for the clam fishery. The results allow proposals of potential improvements to clam-fishing instruments to make the selection processes more effective while promoting a lower impacting fishery, which is essential for clam management.

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Impact of mechanized clam dredging on the discarded megabenthic fauna on the Catalan coast (NW Mediterranean)

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315421000369 ◽

2021 ◽

pp. 1-9

Author(s):

Marc Baeta ◽

Claudia Rubio ◽

Françoise Breton

Keyword(s):

Small Scale ◽

Fishing Activity ◽

Lethal Damage ◽

Catalan Coast ◽

Nw Mediterranean ◽

Chamelea Gallina ◽

Level Scale ◽

Nw Mediterranean Sea ◽

The Impact ◽

Partial Damage

Abstract There is an important small-scale fishery using mechanized dredges and targeting clams (mainly wedge clam Donax trunculus and striped venus clam Chamelea gallina) along the Catalan coast (NW Mediterranean Sea). This study evaluated for the first time the discards and impact of mechanized clam dredging on the Catalan coast. To this end, three surveys were performed on board standard clam vessels (September and November 2016 and January 2017). Surveys were conducted in the three main clam fishing areas (Rosas Bay, South Barcelona and Ebro Delta). The composition of discards and the impact caused to discarded species was assessed using a three-level scale (undamaged; minor or partial damage; and lethal damage). Our study revealed that a large proportion of the catch (between 67–82% weight) is discarded. Even though about 63% of the discarded species were undamaged, 11% showed minor or partial damage and 26% lethal damage. Infaunal and epifaunal species with soft-body or fragile shells were the most impacted by the fishing activity (e.g. the sea urchin Echinocardium mediterraneum (~89%) and the bivalve Ensis minor (~74%)). Our results showed different levels of impact by target species and fishing area.

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Numerical modelling of sediment transport in the Adriatic Sea

Ocean Science Discussions ◽

10.5194/osd-11-1391-2014 ◽

2014 ◽

Vol 11 (3) ◽

pp. 1391-1433 ◽

Cited By ~ 1

Author(s):

A. Guarnieri ◽

A. J. Souza ◽

N. Pinardi ◽

P. Traykovski

Keyword(s):

Sediment Transport ◽

Adriatic Sea ◽

Transport Model ◽

Data Availability ◽

Western Coast ◽

Po River ◽

Northern Adriatic ◽

Coastal Belt ◽

Italian Coasts ◽

The Impact

Abstract. A new sediment transport model, considering currents, tides and waves is presented for the Adriatic Sea basin. The simulations concentrate on the winter of 2002–2003 because of field data availability and interesting intermittent processes occurrence. A process oriented analysis is performed to investigate the impact that Sirocco and Bora wind regimes have on sediment transport. The comparisons of the simulations with the observed data show that the model is capable to capture the main dynamics of sediment transport along the Italian coasts and the sediment concentration within the water column. This latter can reach values up to several g L−1, especially within the first centimetres above the bottom. The sediments are transported mainly southwards along the Italian coasts, consistently with the known literature results, except during Sirocco wind events, which can be responsible for reversing the coastal circulation in the northern area of the basin, and consequently the sediment transport. The resuspension of sediments is also related to the specific wave regimes induced by Bora and Sirocco, the former inducing resuspension events near the coasts while the latter causing a more diffused resuspension regime in the Northern Adriatic basin. Beside the realistic representation of short timescales resuspension/deposition events due to storms, the model was also used to investigate persistent erosion or deposition areas in the Adriatic Sea. Two main depocenters were identified: one, very pronounced, in the surroundings of the Po river delta, and another one a few kilometres off the coast in front of the Ancona promontory. A third region of accumulation, even if less intense, was found to be offshore the southernmost limit of the Gargano region. On the contrary the whole western coast within a distance of a few kilometres from the shore was found to be subject to prevailing erosion. The comparison with observed accumulation and erosion data shows that the model captures well the main depocenters in the domain and the erosion within the very coastal belt of the western side of the basin, but seems to be too erosive in a few areas, in particular those where the contribution of sediment inflow to the sea of some minor but intermittently important rivers is not considered in a realistic way as input to the model.

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“Sermo eorum sicut cancer serpit”. Chromatius of Aquileia against heresies

Vox Patrum ◽

10.31743/vp.3369 ◽

2018 ◽

Vol 68 ◽

pp. 443-455

Author(s):

Miran Sajovic

Keyword(s):

20Th Century ◽

Adriatic Sea ◽

Conference Paper ◽

The North ◽

Trade Center ◽

The Impact ◽

North End

Bishop Chromatius (in office from 388 to 407), whose episcopal see was a cosmopolitan trade-center at the north end of the Adriatic Sea with the name of Aquileia, was one of the most prominent bishops in the period. He is acquainted with notable figures such as Ambrosius, Hieronymus, Rufinus, and Ioannes Chrysostomus and forth. Before being created a bishop, he was the secretary of bishop Valerianus and in the occasion of Council of Aquileia in 381, he had spoken against Arians. This Council was presided by Ambrosius and with its scale it could almost be considered as an ecumenical one. As shown in some of the Chromatius’ sermons, which are unearthed in the 20th century, he opposed not only to the ideas of Arians but also to the teaching of Fotinus, bishop of Sirmium. Chromatius was a very zealous fighter and he practically succeeded to uproot all heretical ideas in his diocese. The academia usually sees him as an anti-Arian theologian. After the Council of Constantinople (381), the Arian heresy seemed to be abated, but Chromatius said in one of his Tractatus, “Cuius (sc. Arii) discipuli hodieque oues Dei fallere ac decipere conantur per aliquantas ecclesias, sed iamdudum, magistro perfidiae prodito, discipuli latere non possunt”; it is evident that, the followers of Arius could still be found (with the mentioning of “hodie”, i.e. today) in the area of Aquileia, meanwhile one must not neglect the presence of the followers of Fotinus of Sirmium. The first part of my conference paper would be a general presentation of the religious situation in Aquileia at the time where Chromatius served as the local bishop; thus I will proceed with an in-depth reading on several passages of the Aquilerian bishop’s sermons (Sermones and Tractatus), in order to show the impact of the those heresies on his works and to identity his theological arguments against them. Among those teachings, there is the “unconquerable faith (invicta fide)”, which led to the surmounting (suppression) of heresies.

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On Abnormally Strong Currents Observed on the Northern Coast of Peru during the 2015-2016 El Niño

Korea Society of Coastal Disaster Prevention ◽

10.20481/kscdp.2021.8.4.205 ◽

2021 ◽

Vol 8 (4) ◽

pp. 205-210

Author(s):

Chang-Woong Shin ◽

Dimitri Gutiérrez

Keyword(s):

Mixed Layer ◽

El Niño ◽

El Nino ◽

Current Data ◽

Kelvin Waves ◽

Coastal Current ◽

Northern Coast ◽

El Niño Event ◽

Strong Current ◽

The Impact

The northern coast of Peru is a region that can rapidly detect the impact of an El Niño. To investigate the effects of the 2015-2016 El Niño on the oceanographic environment of the northern coast of Peru, the temperature and current data obtained from moored equipment at an oil platform were analyzed. Strong coastal along-shore currents of more than 0.60 m·s-1 were observed three times, although the mean current speed was 0.10 m·s-1 flowing toward the south-southwest. After the first strong current, the bottom temperature increased and the mixed layer deepened and remained there during the El Niño event. The temperature reached a maximum after the strong coastal current, then decreased gradually. An analysis of wind and sea surface height anomalies revealed that the coastal strong current was caused by Kelvin waves and the deepening of the mixed layer was not related to local winds, but to coastal Kelvin waves from the equator during the El Niño event.

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Reconstructing the baseline population structure of the exploited bivalve Arca noae in the Northern Adriatic Sea

10.5194/egusphere-egu21-7694 ◽

2021 ◽

Author(s):

Saskia Macharia ◽

Rafał Nawrot ◽

Michaela Berensmeier ◽

Ivo Gallmetzer ◽

Alexandra Haselmair ◽

...

Keyword(s):

Adriatic Sea ◽

Size Structure ◽

Anthropogenic Impacts ◽

Natural State ◽

Published Data ◽

Northern Adriatic Sea ◽

Important Species ◽

Northern Adriatic ◽

Shell Bed ◽

The Impact

The Northern Adriatic Sea is one of the most impacted ecosystems worldwide with a long history of anthropogenic impacts, ranging from overfishing and bottom trawling to eutrophication, deoxygenation and pollution. The impact of these multiple pressures on populations of economically important species is often difficult to evaluate due to paucity of long-term monitoring data. The edible bivalve Noah&#8217;s Ark shell (Arca noae L.) was intensively harvested in the eastern Adriatic Sea until 1949-1950 when it suffered a catastrophic population collapse due to unknown agents. The assessment of its subsequent recovery is hindered by the lack of data on the population size structure prior to that event. To reconstruct the natural baseline state of populations of A. noae before the onset of extensive harvesting, we studied fossil assemblages from two 1.5-m-long sediment cores collected in the southern Gulf of Trieste (off Piran, Slovenia), both recording the last ~9,500 years.The abundance and shell length of A. noae remained low in the lower part of the cores but increased strongly within the oyster-Arca shell bed corresponding to maximum flooding and early highstand sea-level phases (6,500-1,000 years ago). In contrasts, the top 8 cm of the core (the late highstand phase), marked by high concentration of pollutants and organic enrichment, contained only few and small (< 10 mm) A. noae shells. Moreover, no living individuals were found in grab samples taken from the two stations suggesting that the dense populations of A. noae, persisting there for several thousand years, were locally extirpated in the 20th century. To evaluate population recovery in other parts of the NE Adriatic, we compared the size distribution of fossil A. noae from the shell bed interval to the previously published data on living populations of this species sampled along Istrian peninsula between 1966 and 1978. Both fossil and extant populations were characterized by similar median size, modal size class and proportion of specimens > 50 mm (minimal legal landing size). These results suggest that within few decades after the 1949-1950 mass mortality event the size structure of populations of A. noae have largely returned to their earlier, natural state. The recovery was spatially variable, however, as attested by the decline of A. noae populations due to loss of suitable shell-bed habitats in the two studied stations off Piran.

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Chamelea gallina reproductive biology and Minimum Conservation Reference Size: implications for fishery management in the Adriatic Sea

BMC Zoology ◽

10.1186/s40850-021-00096-4 ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

Giada Bargione ◽

Fortunata Donato ◽

Giulio Barone ◽

Massimo Virgili ◽

Pierluigi Penna ◽

...

Keyword(s):

Sexual Maturity ◽

Adriatic Sea ◽

Seawater Temperature ◽

Reproductive Capacity ◽

Great Effort ◽

Important Species ◽

Spawning Period ◽

The Past ◽

Chamelea Gallina ◽

Size At Sexual Maturity

Abstract Background The striped venus clam Chamelea gallina is an economically important species in Adriatic Sea fisheries. The use of hydraulic dredging for its catch has a long history in Italy and its management faced several stages of development in the last 40 years. A great effort has been made in the past two decades to move from poorly or weakly managed fisheries to a well-structured co-management system to improve the sustainability of this fishery. However, a prerequisite for appropriate resource management is a sound knowledge of the biology and reproductive strategy of the species. Results We investigated three major biological features– the gametogenic cycle, size at sexual maturity and partial fecundity – by microscopic, histological and video analysis techniques. We demonstrated that its breeding season is driven by rises in seawater temperature and chlorophyll-a concentration and that its spawning period lasted from March to September. Size at sexual maturity was reached very early in the life cycle. As regards partial fecundity – the number of mature oocytes potentially released by females with ripe gonads in a single release event – varied in relation to size. Nevertheless, the reduction on the Minimum Conservation Reference Size (MCRS) from 25 to 22 mm (Delegated Regulation (EU) 2020/2237) lead to a 40% reduction in the number of emitted eggs. Conclusions We suggest that the ability of Adriatic clam stocks to withstand the strong fishing pressure of the past 40 years and the present one is due to their high reproductive potential and multiple spawning events combined with the effect of management measures (closed areas/seasons, quota, MCRS) and technical constraints on the gear and the sieve on board. Moreover, since the reduced MCRS for Venus shells is still larger than the size at maturity, it will probably not be detrimental to the reproductive capacity of the stock.

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Investigating triggering mechanisms for the large hailstorm event of July 10th, 2019 on the Adriatic Sea

10.5194/egusphere-egu21-3662 ◽

2021 ◽

Author(s):

Antonio Ricchi ◽

Vincenzo Mazzarella ◽

Lorenzo Sangelantoni ◽

Gianluca Redaelli ◽

Rossella Ferretti

Keyword(s):

Adriatic Sea ◽

Initial Conditions ◽

Central Italy ◽

Radar Data ◽

Sensitivity Study ◽

Convective Cell ◽

Sea Surface ◽

Microphysics Scheme ◽

The Balkans ◽

The Impact

<div> A severe weather events hit Italy on July 9-10, 2019 causing heavy damages by the falling of large-size hail. A trough from Northern Europe affected Italy and the Balkans advecting cold air on the Adriatic Sea. The intrusion of relatively cold and dry air on the Adriatic Sea, in a first stage through the "Bora jets" generated by the Dinaric Alps gave rise to a frontal structure on the ground, which rapidly moved from North to South Adriatic. The large thermal gradient (also with the sea surface), the interaction with the complex orography and the coastal zone, generated several storm structures along the eastern Italian coast. In particular, on 10 July 2019 between 8UTC and 12UTC a deep convective cell (probably a supercell) developed along the coast North of the city of Pescara, producing intense rainfall (accumulated rainfall reaching 130 mm/3h) and a violent hailstorm with hailstones larger than 10 cm in diameter. The storm quickly moved southward, evolving into a complex multicellular structure clearly visible by observing radar data. In this work the frontal dynamics and the genesis of the storm cell are investigated using the numerical model WRF (Weather Research and Forecasting system). Numerical experiments are carried out using a 1 km grid on Central Italy, initialized using the ECMWF dataset and the Sea Surface Temperature (SST) taken by MFS-CMEMS Copernicus dataset. The sensitivity study investigated both the impact of the initial conditions, the quality and the anomaly of the SST on the Adriatic basin in those days. Furthermore, in order to quantify the importance of the use of different microphysics, Planetary boundary Layer (PBL) and radiative schemes, several experiments are performed. The role of orography in the development and location of the convective cell is also investigated. Preliminary results show that initialization and SST played a fundamental role. In particular, the initialization several hours before the event, coupled with a detailed SST allows to correctly reproduce the atmospheric fields. The microphysics scheme turned out to play a key role for this event by showing a significant greater impact than the PBL, in terms of frontal genesis on both the synoptic and local scale. </div>

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Orographic influences on the Adriatic sirocco wind

Annales Geophysicae ◽

10.5194/angeo-25-1263-2007 ◽

2007 ◽

Vol 25 (6) ◽

pp. 1263-1267 ◽

Cited By ~ 30

Author(s):

Z. Pasarić ◽

D. Belušić ◽

Z. B. Klaić

Keyword(s):

Adriatic Sea ◽

Meteorological Model ◽

Mesoscale Meteorological Model ◽

Western Adriatic Current ◽

Ecmwf Model ◽

The Impact

Abstract. Differences between meteorological fields over the Adriatic Sea as predicted by the mesoscale meteorological model ALADIN/HR and global ECMWF model, for sirocco episodes between November 2002 and September 2003, are analysed. Results indicate that the orography, namely Gargano Mountains and Apennines, may have a significant effect on the sirocco airflow. A brief discussion is given on the impact of the sirocco wind curl on the Western Adriatic Current (WAC).

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