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 ◽  
...  

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.

Water ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 2280 ◽  
Author(s):  
Federica Grilli ◽  
Stefano Accoroni ◽  
Francesco Acri ◽  
Fabrizio Bernardi Aubry ◽  
Caterina Bergami ◽  
...  

Long-term data series (1971–2015) of physical and biogeochemical parameters were analyzed in order to assess trends and variability of oceanographic conditions in the northern Adriatic Sea (NAS), a mid-latitude shallow continental shelf strongly impacted by river discharges, human activities and climate changes. Interpolation maps and statistical models were applied to investigate seasonal and spatial variability, as well as decadal trends of temperature, salinity, chlorophyll-a and nutrients. This analysis shows that sea surface temperature increased by +0.36% year−1 over four decades. Annual mean flow of the Po River markedly changed due to the occurrence of periods of persistent drought, whereas the frequency of flow rates higher than 3000 m3 s−1 decreased between 2006 and 2015. Moreover, we observed a long-term decrease in surface phosphate concentrations in Po River water (−1.34% year−1) and in seawater (in summer −2.56% year−1) coupled, however, to a significant increase in nitrate concentration in seawater (+3.80% year−1) in almost all seasons. These changes indicate that the nutrient concentrations in the NAS have been largely modulated, in the last forty years, by the evolution of environmental management practices and of the runoff. This implies that further alteration of the marine environment must be expected as a consequence of the climate changes.


Author(s):  
Elena Pavoni ◽  
Elisa Petranich ◽  
Sergio Signore ◽  
Giorgio Fontolan ◽  
Stefano Covelli

Mercury (Hg) contamination in the Gulf of Trieste (northern Adriatic Sea) due to mining activity in Idrija (Slovenia) still represents an issue of environmental concern. The Isonzo/Soča River’s freshwater inputs have been identified as the main source of Hg into the Gulf, especially following periods of medium-high discharge. This research aims to evaluate the occurrence and distribution of dissolved (DHg) and particulate (PHg) Hg along the water column in the northernmost sector of the Gulf, a shallow and sheltered embayment suitable for the accumulation of fine sediments. Sediment and water samples were collected under unperturbed and perturbed environmental conditions induced by natural and anthropogenic factors. Mercury in the sediments (0.77–6.39 µg g−1) and its relationship to grain size were found to be consistent with previous research focused on the entire Gulf, testifying to the common origin of the sediment. Results showed a notable variability of DHg (<LOD–149 ng L−1) and PHg (0.39–12.5 ng L−1) depending on the interaction between riverine and marine hydrological conditions. Mercury was found to be mainly partitioned in the suspended particles, especially following periods of high discharge, thus confirming the crucial role of the river inputs in regulating PHg distribution in the Gulf.


2021 ◽  
Author(s):  
Saskia Macharia ◽  
Rafał Nawrot ◽  
Michaela Berensmeier ◽  
Ivo Gallmetzer ◽  
Alexandra Haselmair ◽  
...  

&lt;p&gt;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&amp;#8217;s Ark shell (&lt;em&gt;Arca noae &lt;/em&gt;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 &lt;em&gt;A. noae&lt;/em&gt; 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.&lt;/p&gt;&lt;p&gt;The abundance and shell length of &lt;em&gt;A. noae&lt;/em&gt; remained low in the lower part of the cores but increased strongly within the oyster-&lt;em&gt;Arca&lt;/em&gt; 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 (&lt; 10 mm) &lt;em&gt;A. noae&lt;/em&gt; shells. Moreover, no living individuals were found in grab samples taken from the two stations suggesting that the dense populations of &lt;em&gt;A. noae, &lt;/em&gt;&lt;span&gt;persisting &lt;/span&gt;&lt;span&gt;there&lt;/span&gt; &lt;span&gt;for&lt;/span&gt;&lt;span&gt; several thousand years, &lt;/span&gt;were locally extirpated in the 20&lt;sup&gt;th&lt;/sup&gt; century. To evaluate population recovery in other parts of the NE Adriatic, we compared the size distribution of&lt;em&gt; &lt;/em&gt;fossil&lt;em&gt; &lt;/em&gt;&lt;em&gt;A. noae&lt;/em&gt; from the shell bed interval to the previously published data on living populations of this species sampled&lt;em&gt; &lt;/em&gt;along Istrian peninsula between 1966 and 1978. Both fossil and extant populations were characterized by similar &lt;span&gt;median &lt;/span&gt;&lt;span&gt;size, &lt;/span&gt;&lt;span&gt;modal size &lt;/span&gt;&lt;span&gt;class and&lt;/span&gt;&lt;span&gt; proportion of &lt;/span&gt;&lt;span&gt;specimens &gt; 50 mm &lt;/span&gt;&lt;span&gt;(minimal legal landing size). &lt;/span&gt;&lt;span&gt;These results suggest that within few &lt;/span&gt;&lt;span&gt;decades&lt;/span&gt;&lt;span&gt; after the &lt;/span&gt;&lt;span&gt;1949-1950 &lt;/span&gt;&lt;span&gt;mass mortality event &lt;/span&gt;&lt;span&gt;the size structure of populations &lt;/span&gt;&lt;span&gt;of&lt;/span&gt; &lt;span&gt;&lt;em&gt;A. noae&lt;/em&gt;&lt;/span&gt; &lt;span&gt;have largely returned to their earlier, natural state.&lt;/span&gt;&lt;span&gt; The recovery was &lt;/span&gt;&lt;span&gt;spatially variable, however, as attested by&lt;/span&gt;&lt;span&gt; the decline of&lt;/span&gt; &lt;span&gt;&lt;em&gt;A. noae&lt;/em&gt;&lt;/span&gt; &lt;span&gt;populations &lt;/span&gt;&lt;span&gt;due to loss of &lt;/span&gt;&lt;span&gt;suitable shell-bed habitat&lt;/span&gt;&lt;span&gt;s&lt;/span&gt;&lt;span&gt; in&lt;/span&gt;&lt;span&gt; the two &lt;/span&gt;&lt;span&gt;studied&lt;/span&gt;&lt;span&gt; station&lt;/span&gt;&lt;span&gt;s&lt;/span&gt;&lt;span&gt; off Piran.&lt;/span&gt;&lt;/p&gt;


Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3430
Author(s):  
Adriano Sfriso ◽  
Alessandro Buosi ◽  
Yari Tomio ◽  
Abdul-Salam Juhmani ◽  
Stefania Chiesa ◽  
...  

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.


Nutrients ◽  
2018 ◽  
Vol 10 (3) ◽  
pp. 278 ◽  
Author(s):  
Jadran Faganeli ◽  
Ingrid Falnoga ◽  
Milena Horvat ◽  
Katja Klun ◽  
Lovrenc Lipej ◽  
...  

2008 ◽  
Vol 64 (2) ◽  
pp. 219-229 ◽  
Author(s):  
Alessandro Paoli ◽  
Mauro Celussi ◽  
Paola Del Negro ◽  
Serena Fonda Umani ◽  
Laura Talarico

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