scholarly journals Distribution, diet and relationships of the invasive ctenophore Mnemiopsis leidyi with anchovies and zooplankton, in the northeastern Adriatic Sea

2021 ◽  
Author(s):  
ANDREA BUDIŠA ◽  
PAOLO PALIAGA ◽  
TEA JURETIĆ ◽  
DAVOR LUČIĆ ◽  
NASTJENJKA SUPIĆ ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Adriatic Sea ◽  
Monitoring Program ◽  
Mnemiopsis Leidyi ◽  
Western Coast ◽  
Northern Adriatic ◽  
Fish Stocks ◽  
Marine Food Webs ◽  
International Monitoring ◽  
Marine Food

Blooms of invasive ctenophore Mnemiopsis leidyi can have massive consequences on fish stocks and marine food webs. The distribution, abundance and diet of this ctenophore were investigated in the northeastern (NE) Adriatic between 2016 and 2019. The abundance of M. leidyi was determined daily along the coast of Rovinj (Croatia), and its spatial distribution monitored by visual census from research vessels and by pelagic trawl during acoustic surveys in September of each year. Mesozooplankton samples were collected along the western coast of Istria by vertical tows from the bottom to the surface. Spatial distribution and abundance of anchovy (Engraulis encrasicolus) assemblages were determined by geo-referenced hydro-acoustic sampling using a scientific echosounder. Large swarms of M. leidyi covering several km2 were regularly reported between July and November extending up to 25 NM from the western coast of the Istrian peninsula and reaching maximum offshore densities of 270 individuals per m2. The abundance of anchovy in the areas where M. leidyi was present evidently decreased. The content of M. leidyi’s digestive tract and plankton samples consisted both mainly of cladocerans, copepods, pteropods, echinodermata and bivalvia larvae. Results indicate that M. leidyi may accumulate and increase its abundance in the stagnant and trophically rich areas of the northern Adriatic gyres, spreading to the surrounding larger areas with currents. We assume that M. leidyi presence correlates with a decrease in anchovy population due to competition for food (zooplankton). Our findings support the importance of implementing an international monitoring program throughout the Adriatic Sea and demonstrate the ability of current MEDIAS surveys to detect changes in the pelagic ecosystem throughout surveyed areas.

scholarly journals Numerical modelling of sediment transport in the Adriatic Sea

2014 ◽  
Vol 11 (3) ◽  
pp. 1391-1433 ◽  
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.

scholarly journals Spatial distribution of suspended solids during short-term high river discharge in the Bay of Koper, northern Adriatic Sea

2018 ◽  
Vol 19 (1) ◽  
pp. 36 ◽  
Author(s):  
ROK SOCZKA MANDAC ◽  
DUŠAN ŽAGAR
Keyword(s):  
Spatial Distribution ◽  
River Discharge ◽  
Suspended Solids ◽  
Adriatic Sea ◽  
Anthropogenic Influences ◽  
Short Term ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
River Flooding ◽  
The Impact

The Bay of Koper (BoK) located in the Gulf of Trieste (northern Adriatic Sea) is subject to a variety of anthropogenic influences; pollutants from inland are transported to the sea by the local rivers. The impact of high river discharge on suspended solids distribution was assessed by analysing results of an extensive measurement campaign conducted during two episodes of river flooding. The spatial analysis demonstrated the area influenced by fresh water and the distribution of inorganic suspended solids (ISS). The results were then used to calibrate the PCFLOW3D model and to simulate two episodes. A correlation was identified between the measurements and short-term simulations found in the central part of the bay. The results confirm the methods and the model used in this study to be appropriate for studying complex suspended solids processes in coastal areas.

scholarly journals Disinfection By-Products (DBPs) in Seawaters, Sediments and Biota near a Marine Terminal for Regasifying Liquefied Natural Gas (LNG) in the Northern Adriatic Sea (Italy)

Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2175
Author(s):  
Federica Cacciatore ◽  
Marina Amici ◽  
Giulia Romanelli ◽  
Valentina Bernarello ◽  
Gianluca Franceschini ◽  
...  
Keyword(s):  
Environmental Impact ◽  
Adriatic Sea ◽  
Monitoring Program ◽  
Fish Fauna ◽  
Liquefied Natural Gas ◽  
Marine Waters ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Operation Phase ◽  
By Products

In 2009, the first Italian offshore LNG terminal, located approximately 12 km from the coast of Italy in the Northern Adriatic Sea, started its operation phase. Even if the active chlorine concentration in the discharged seawater is within limits set by Italian regulations (0.2 mg/L), to verify the environmental impact of disinfection by-products (DBPs) on the ecosystem, a specific monitoring program was scheduled from 2010 to 2015. The present study is the first displaying results of DBPs in marine waters of the Adriatic Sea. During the first two years of monitoring activities, DBPs were slightly above limit of quantifications (LOQs) in all investigated matrices and limited to the nearest area around the terminal. In these surveys, bromoform was the most frequently detected compound in seawaters, while haloacetic acid presence, as well as transplanted mussels and fish fauna, mostly characterized sediments. In the following surveys, levels were mostly negligible in all matrices investigated, with values mostly below the specific LOQs of the different compounds.

scholarly journals Scyphomedusae and Ctenophora of the Eastern Adriatic: Historical Overview and New Data

Diversity ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 186
Author(s):  
Branka Pestorić ◽  
Davor Lučić ◽  
Natalia Bojanić ◽  
Martin Vodopivec ◽  
Tjaša Kogovšek ◽  
...  
Keyword(s):  
Adriatic Sea ◽  
Seasonal Pattern ◽  
Geographical Location ◽  
Distribution Patterns ◽  
Mnemiopsis Leidyi ◽  
Future Studies ◽  
Phenological Data ◽  
Pelagia Noctiluca ◽  
Regional Trends ◽  
Clear Seasonal Pattern

One of the obstacles to detecting regional trends in jellyfish populations is the lack of a defined baseline. In the Adriatic Sea, the jellyfish fauna (Scyphozoa and Ctenophora) is poorly studied compared to other taxa. Therefore, our goal was to collect and systematize all available data and provide a baseline for future studies. Here we present phenological data and relative abundances of jellyfish based on 2010–2019 scientific surveys and a “citizen science” sighting program along the eastern Adriatic. Inter-annual variability, seasonality and spatial distribution patterns of Scyphomedusae and Ctenophore species were described and compared with existing historical literature. Mass occurrences with a clear seasonal pattern and related to the geographical location were observed for meroplanktonic Scyphomedusae Aurelia solida, Rhizostoma pulmo, and to a lesser extent Chrysaora hysoscella, Cotylorhiza tuberculata and Discomedusa lobata. Holoplanktonic Pelagia noctiluca also formed large aggregations, which were seasonally less predictable and restricted to the central and southern Adriatic. Four species of Ctenophora produced blooms limited to a few areas: Bolinopsis vitrea, Leucothea multicornis, Cestum veneris and the non-native Mnemiopsis leidyi. However, differences between Adriatic subregions have become less pronounced since 2014. Our results suggest that gelatinous organisms are assuming an increasingly important role in the Adriatic ecosystem, which may alter the balance of the food web and lead to harmful and undesirable effects.

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