scholarly journals Sediment Carbon Variations in the Venice Lagoon and Other Transitional Water Systems of the Northern Adriatic Sea

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3430
Author(s):  
Adriano Sfriso ◽  
Alessandro Buosi ◽  
Yari Tomio ◽  
Abdul-Salam Juhmani ◽  
Stefania Chiesa ◽  
...  
Keyword(s):  
Inorganic Carbon ◽  
Anthropogenic Impacts ◽  
Venice Lagoon ◽  
Total Carbon ◽  
Central Basin ◽  
Northern Adriatic Sea ◽  
Biological Origin ◽  
Northern Adriatic ◽  
High Concentrations ◽  
Shell Fragments

The concentrations of inorganic, organic and total carbon, and some sedimentary parameters (sediment density, fines, pH, and shell fragments), have been analyzed in surface sediments of the Venice Lagoon since 1987. Environmental scenarios, characterized by different anthropogenic impacts, have been considered, especially in the central basin where more information is available. Data collected in 2009 in the lagoons and ponds of Po Delta, in Comacchio Valleys and Pialassa della Baiona have been also considered and analyzed together with those recorded in the whole Venice Lagoon in 2011. The results show a strong correlation of the inorganic carbon (Cinorg) with the carbonatic or siliceous origins of the sediments and changes of both Cinorg and organic carbon (Corg) according to different anthropogenic impacts, especially eutrophication and clam-fishing activities. Higher sediment density, grain-size, and pH were associated to good-high ecological conditions and the higher presence of inorganic carbon of biological origin (shell fragments and calcified macroalgal fragments). Conversely, Corg, which is associated to eutrophic conditions, was strongly affected by the sediment disturbance and the presence of high concentrations of bivalves which enhance its consumption.

scholarly journals Trends of Nitrogen and Phosphorus in Surface Sediments of the Lagoons of the Northern Adriatic Sea as a Study Case

Water ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 2914
Author(s):  
Adriano Sfriso ◽  
Alessandro Buosi ◽  
Yari Tomio ◽  
Abdul-Salam Juhmani ◽  
Michele Mistri ◽  
...  
Keyword(s):  
Surface Sediments ◽  
Adriatic Sea ◽  
Organic Phosphorus ◽  
Anthropogenic Impacts ◽  
Venice Lagoon ◽  
Nutrient Concentrations ◽  
Nitrogen And Phosphorus ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Po Delta

The analysis of nutrient concentrations in surface sediments is a reliable tool for assessing the trophic status of a water body. Nitrogen and phosphorus concentrations are strongly related to the sediment characteristics but are mainly driven by anthropogenic impacts. The results of the determination of total nitrogen and total inorganic and organic phosphorus in surface sediments of the lagoons and ponds of the northwestern Adriatic Sea (Marano-Grado, Venice, Po Delta, Comacchio Valleys, Pialassa della Baiona) show the merit of this approach. Indeed, when previous data are available, the ratio between the actual and background values can provide useful information on the trophic changes that have occurred in the most recent times, and the results can also explain the conditions present in less studied environments. In this context, numerous studies performed in the Venice lagoon since the second half of the 20th century during different environmental scenarios provide mean concentration ranges and propose the main causes of changes. The results of single datasets available for the other lagoons fall into scenarios that occurred in the Venice lagoon. At present, the most eutrophic basins are Pialassa della Baiona, the Po Delta lagoons and ponds and the Comacchio valleys due to industrial effluents, fish farming and clam harvesting, respectively, whereas the Venice lagoon is now experiencing environmental recovery.

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

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

<p>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’s Ark shell (<em>Arca noae </em>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 <em>A. noae</em> 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.</p><p>The abundance and shell length of <em>A. noae</em> remained low in the lower part of the cores but increased strongly within the oyster-<em>Arca</em> 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) <em>A. noae</em> shells. Moreover, no living individuals were found in grab samples taken from the two stations suggesting that the dense populations of <em>A. noae, </em><span>persisting </span><span>there</span> <span>for</span><span> several thousand years, </span>were locally extirpated in the 20<sup>th</sup> century. To evaluate population recovery in other parts of the NE Adriatic, we compared the size distribution of<em> </em>fossil<em> </em><em>A. noae</em> from the shell bed interval to the previously published data on living populations of this species sampled<em> </em>along Istrian peninsula between 1966 and 1978. Both fossil and extant populations were characterized by similar <span>median </span><span>size, </span><span>modal size </span><span>class and</span><span> proportion of </span><span>specimens > 50 mm </span><span>(minimal legal landing size). </span><span>These results suggest that within few </span><span>decades</span><span> after the </span><span>1949-1950 </span><span>mass mortality event </span><span>the size structure of populations </span><span>of</span> <span><em>A. noae</em></span> <span>have largely returned to their earlier, natural state.</span><span> The recovery was </span><span>spatially variable, however, as attested by</span><span> the decline of</span> <span><em>A. noae</em></span> <span>populations </span><span>due to loss of </span><span>suitable shell-bed habitat</span><span>s</span><span> in</span><span> the two </span><span>studied</span><span> station</span><span>s</span><span> off Piran.</span></p>

scholarly journals Climatic and Anthropogenic Impacts on Environmental Conditions and Phytoplankton Community in the Gulf of Trieste (Northern Adriatic Sea)

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2652 ◽  
Author(s):  
Stefano Cozzi ◽  
Marina Cabrini ◽  
Martina Kralj ◽  
Cinzia De Vittor ◽  
Massimo Celio ◽  
...  
Keyword(s):  
Management Practices ◽  
Phytoplankton Community ◽  
Anthropogenic Impacts ◽  
Nutrient Balance ◽  
Environmental Data ◽  
Data Series ◽  
Nutrient Loads ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Gulf Of Trieste

During the last century, human activities have exerted an increasing pressure on coastal ecosystems, primarily inducing their eutrophication, with a more recent partial mitigation of this phenomenon where improvements of environmental management practices were adopted. However, a reanalysis of the pressures on coastal zones and surrounding drainage basins is needed because of the alterations induced nowadays by the climate changes. A comparative analysis of long-term oceanographic and environmental data series (1986–2018) was performed, in order to highlight the effects of anthropogenic and climatic disturbances on the phytoplankton community in the Gulf of Trieste (GoT). After the 1980s, the decline in phytoplankton abundance was matched to increasing periods of low runoff, an overall deficit of the precipitation and to a decrease in phosphate availability in the coastal waters (−0.003 µmol L−1 yr−1), even in the presence of large riverine inputs of nitrogen and silicates. This trend of oligotrophication was reversed in the 2010s by the beginning of a new and unexpected phase of climatic instability, which also caused changes of the composition and seasonal cycle of the phytoplankton community. Beyond the management of nutrient loads, it was shown that climatic drivers such as seawater warming, precipitation and wind regime affect both nutrient balance and phytoplankton community in this coastal zone.

scholarly journals Variability of currents in front of the Venice Lagoon, Northern Adriatic Sea

2008 ◽  
Vol 26 (4) ◽  
pp. 731-746 ◽  
Author(s):  
S. Cosoli ◽  
M. Gačić ◽  
A. Mazzoldi
Keyword(s):  
Water Column ◽  
Wind Stress ◽  
Time Scale ◽  
Adriatic Sea ◽  
Sea Breeze ◽  
Venice Lagoon ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Modes Of Variability ◽  
Tidal Signal

Abstract. Time scales and modes of variability of the flow in the water column in the Northern Adriatic Sea for late summer 2002 are described based on current record from a single bottom-mounted ADCP in the shallow-water area in front of the Venice Lagoon. The time averaged flow was directed 277° E (CCW), roughly aligned with the coastline, with typical magnitudes in the range 4–6 cm/s and a limited, not significant clockwise veering with depth. Tidal forcing was weak and mainly concentrated in the semidiurnal frequency band, with a barotropic (depth-independent) structure. On a diurnal time scale, tidal signal was biased by the sea-breeze regime and was characterized by a clockwise veering with depth according to the Ekman spiral. A complex EOF analysis on the velocity profile time series extracted two dominant spatial modes of variability, which explained more than 90% of the total variance in the current field. More than 78% of the total variance was accounted for by the first EOF mode, with a barotropic structure that contained the low-frequency components and the barotropic tidal signal at semidiurnal and diurnal frequencies. The second mode had a baroclinic structure with a zero-crossing at mid-depth, which was related with the response of the water column to the high-frequency wind-driven diurnal sea breeze variability. The response of low-passed non-tidal currents to local wind stress was fast and immediate, with negligible temporal lag up to mid-depth. Currents vectors were pointing to the right of wind stress, as expected from the surface Ekman veering, but with angles smaller than the expected ones. A time lag in the range 10 to 11 h was found below 8 m depth, with current vectors pointing to the left of wind stress and a counterclockwise veering towards the bottom. The delay was consistent with the frictional adjustment time scale describing the dynamics of a frictionally dominated flow in shallow water, thus suggesting the importance of bottom friction on the motion over the entire water column.

scholarly journals Dynamics of environmental conditions during the decline of a <i>Cymodocea nodosa</i> meadow

2020 ◽  
Vol 17 (12) ◽  
pp. 3299-3315 ◽  
Author(s):  
Mirjana Najdek ◽  
Marino Korlević ◽  
Paolo Paliaga ◽  
Marsej Markovski ◽  
Ingrid Ivančić ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Light Availability ◽  
Plant Performance ◽  
Regular Growth ◽  
Cymodocea Nodosa ◽  
Negative Effects ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Light Reduction ◽  
High Concentrations

Abstract. The dynamics of the physicochemical and biological parameters were followed during the decline of a Cymodocea nodosa meadow in the northern Adriatic Sea from July 2017 to October 2018. During the regular growth of C. nodosa from July 2017 to March 2018, the species successfully adapted to the changes in environmental conditions and prevented H2S accumulation by its reoxidation, supplying the sediment with O2 from the water column and/or leaf photosynthesis. The C. nodosa decline was most likely triggered in April 2018 when light availability to the plant was drastically reduced due to increased seawater turbidity that resulted from increased terrigenous input, indicated by a decrease in salinity accompanied with a substantial increase in particulate matter concentration, combined with resuspension of sediment and elevated autotrophic biomass. Light reduction impaired photosynthesis of C. nodosa and the oxidation capability of belowground tissue. Simultaneously, a depletion of oxygen due to intense oxidation of H2S occurred in the sediment, thus creating anoxic conditions in most of the rooted areas. These linked negative effects on the plant performance caused an accumulation of H2S in the sediments of the C. nodosa meadow. During the decay of aboveground and belowground tissues, culminating in August 2018, high concentrations of H2S were reached and accumulated in the sediment as well as in bottom waters. The influx of oxygenated waters in September 2018 led to the re-establishment of H2S oxidation in the sediment and remainder of the belowground tissue. Our results indicate that if disturbances of environmental conditions, particularly those compromising the light availability, take place during the recruitment phase of plant growth when metabolic needs are at a maximum and stored reserves minimal, a sudden and drastic decline of the seagrass meadow occurs.

scholarly journals Macrophytes: A Temporary Sink for Microplastics in Transitional Water Systems

Water ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3032
Author(s):  
Andrea Augusto Sfriso ◽  
Yari Tomio ◽  
Abdul-Salam Juhmani ◽  
Adriano Sfriso ◽  
Cristina Munari ◽  
...  
Keyword(s):  
Adriatic Sea ◽  
Venice Lagoon ◽  
Water Systems ◽  
Specific Pattern ◽  
Fresh Weight ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Marine Macrophytes ◽  
Species Specific ◽  
A Site

Marine macrophytes are hypothesized to be a major temporary sink for microplastics. In this study, microplastic contamination was investigated in 15 macroalgal species and one seagrass from different sites in two lagoons of the northern Adriatic Sea: the Goro lagoon and the Venice lagoon. A high percentage (94%) of the macrophyte samples contained microplastics, ranging from 0.16 to 330 items g−1 fw, with the prevalent size in the range 30–90 µm and an average contamination per unit of fresh weight of 14 items g−1 fw. Microplastic contamination displayed a site-specific, rather than a species-specific, pattern of accumulation. In addition, exopolysaccharides (EPS) displayed a significant positive correlation with the microplastics ononcontamination on macrophytes acting as glue for the plastic particles available in the water column.

scholarly journals Tracing the effects of eutrophication on molluscan communities in sediment cores: outbreaks of an opportunistic species coincide with reduced bioturbation and high frequency of hypoxia in the Adriatic Sea

Paleobiology ◽  
2018 ◽  
Vol 44 (4) ◽  
pp. 575-602 ◽  
Author(s):  
Adam Tomašových ◽  
Ivo Gallmetzer ◽  
Alexandra Haselmair ◽  
Darrell S. Kaufman ◽  
Martina Kralj ◽  
...  
Keyword(s):  
Twentieth Century ◽  
Adriatic Sea ◽  
Anthropogenic Impacts ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
Macrobenthic Communities ◽  
Opportunistic Species ◽  
Early Twentieth Century ◽  
Late Twentieth ◽  
Late Twentieth Century

AbstractEstimating the effects and timing of anthropogenic impacts on the composition of macrobenthic communities is challenging, because early twentieth-century surveys are sparse and the corresponding intervals in sedimentary sequences are mixed by bioturbation. Here, to assess the effects of eutrophication on macrobenthic communities in the northern Adriatic Sea, we account for mixing with dating of the bivalve Corbula gibba at two stations with high accumulation (Po prodelta) and one station with moderate accumulation (Isonzo prodelta). We find that, first, pervasively bioturbated muds typical of highstand conditions deposited in the early twentieth century were replaced by muds with relicts of flood layers and high content of total organic carbon (TOC) deposited in the late twentieth century at the Po prodelta. The twentieth century shelly muds at the Isonzo prodelta are amalgamated but also show an upward increase in TOC. Second, dating of C. gibba shells shows that the shift from the early to the late twentieth century is characterized by a decrease in stratigraphic disorder and by an increase in temporal resolution of assemblages from ~25–50 years to ~10–20 years in both regions. This shift reflects a decline in the depth of the fully mixed layer from more than 20 cm to a few centimeters. Third, the increase in abundance of the opportunistic species C. gibba and the loss of formerly abundant, hypoxia-sensitive species coincided with the decline in bioturbation, higher preservation of organic matter, and higher frequency of seasonal hypoxia in both regions. This depositional and ecosystem regime shift occurred in ca. a.d. 1950. Therefore, the effects of enhanced food supply on macrobenthic communities were overwhelmed by oxygen depletion, even when hypoxic conditions were limited to few weeks per year in the northern Adriatic Sea. Preservation of trends in molluscan abundance and flood events in cores was enhanced by higher frequency of hypoxia that reduced bioturbation in the late twentieth century.

scholarly journals Expected Shifts in Nekton Community Following Salinity Reduction: Insights into Restoration and Management of Transitional Water Habitats

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1354 ◽  
Author(s):  
Luca Scapin ◽  
Matteo Zucchetta ◽  
Andrea Bonometto ◽  
Alessandra Feola ◽  
Rossella Boscolo Brusà ◽  
...  
Keyword(s):  
Community Structure ◽  
Shallow Water ◽  
Coastal Lagoons ◽  
Venice Lagoon ◽  
Northern Adriatic Sea ◽  
Management Tools ◽  
Important Species ◽  
Northern Adriatic ◽  
Functional Perspective ◽  
Salinity Reduction

A restoration project is planned to take place in the northern Venice lagoon (northern Adriatic Sea, Italy), aiming at introducing freshwater into a confined shallow water lagoon area and recreating transitional water habitats. This work describes the shifts in the nekton (fish and decapods) community structure to be expected following the future salinity decrease in the restoration area. Nekton was sampled at a series of natural shallow water sites located along salinity gradients in the Venice lagoon. A multivariate GLM approach was followed in order to predict species biomass under the salinity and environmental conditions expected after restoration. Biomass of commercially important species, as well as species of conservation interest, is predicted to increase following salinity reduction and habitat changes. From a functional perspective, an increase in biomass of hyperbenthivores-zooplanctivores, hyperbenthivores-piscivores and detritivores is also expected. This study emphasises the efficacy of a predictive approach for both ecological restoration and ecosystem management in transitional waters. By providing scenarios of community structure, the outcomes of this work could be employed in future evaluations of restoration success in the Venice lagoon, as well as to develop management tools to forecast the effects of alterations of salinity regimes in coastal lagoons due to climate change.

scholarly journals Molluscan benthic communities at Brijuni Islands (northern Adriatic Sea) shaped by Holocene sea-level rise and recent human eutrophication and pollution

The Holocene ◽  
2018 ◽  
Vol 28 (11) ◽  
pp. 1801-1817 ◽  
Author(s):  
Sara-Maria Schnedl ◽  
Alexandra Haselmair ◽  
Ivo Gallmetzer ◽  
Anna-Katharina Mautner ◽  
Adam Tomašových ◽  
...  
Keyword(s):  
Sea Level ◽  
Adriatic Sea ◽  
Environmental Changes ◽  
Anthropogenic Impacts ◽  
Benthic Communities ◽  
Marine Species ◽  
Benthic Assemblages ◽  
Northern Adriatic Sea ◽  
Northern Adriatic ◽  
The Impact

The effects of and the interplay between natural and anthropogenic influences on the composition of benthic communities over long time spans are poorly understood. Based on a 160-cm-long sediment core collected at 44 m water depth in the NE Adriatic Sea (Brijuni Islands, Croatia), we document changes in molluscan communities since the Holocene transgression ~11,000 years ago and assess how they were shaped by environmental changes. We find that (1) a transgressive lag deposit with a mixture of terrestrial and marine species contains abundant seagrass-associated gastropods and epifaunal suspension-feeding bivalves, (2) the maximum-flooding phase captures the establishment of epifaunal bivalve-dominated biostromes in the photic zone, and (3) the highstand phase is characterized by increasing infaunal suspension feeders and declining seagrass-dwellers in bryozoan-molluscan muddy sands. Changes in the community composition between the transgressive and the highstand phase can be explained by rising sea level, reduced light penetration, and increase in turbidity, as documented by the gradual up-core shift from coarse molluscan skeletal gravel with seagrass-associated molluscs to bryozoan sandy muds. In the uppermost 20 cm (median age <200 years), however, epifaunal and grazing species decline and deposit-feeding and chemosymbiotic species increase in abundance. These changes concur with rising concentrations of nitrogen and organic pollutants due to the impact of eutrophication, pollution, and trawling in the 20th century. The late highstand benthic assemblages with abundant bryozoans, high molluscan diversity, and abundance of soft-bottom epi- and infaunal filter feeders and herbivores represent the circalittoral baseline community largely unaffected by anthropogenic impacts.

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