Search

Copyright of People & Nature is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The evolution of alluvial megafans has mainly been investigated in unconfined settings; however, at the boundary of these large depositional systems, the development of fluvial channels can be affected by structural constraints with regional extent. Here we present the study of the eastern sector of the megafan of Isonzo River, in the Gulf of Trieste, where this system fed through the southern Alps is constrained by the Karst and Istria cliffs. Although this area is now submerged under the northern Adriatic Sea, stratigraphy from seismo-acoustic profiles, drill cores and multi-beam bathymetry allows us to reconstruct the paleochannel system of the Isonzo River in detail, which was likely active within the period of 21–17.5 ka cal BP, at the end of LGM. This was reconstructed for over 50 km and currently represents the longest abandoned fluvial channel in the Mediterranean seabed. The occurrence of the mountain fringe and competition with nearby alluvial systems forced the paleochannel to follow the present coastline and conditioned the slope of its thalweg to decrease almost to null, resulting the transformation from the megafan to the undifferentiated alluvial plain. [ABSTRACT FROM AUTHOR]

A specimen of a sixgill bluntnose shark, Hexanchus griseus (Bonnaterre, 1788), was caught 1.5 NM north of Cape Ronek (Izola, Slovenia) in a fishing net for large-sized flatfish (such as turbot) on 28 January 2018. Three other older cases of catch of sixgill bluntnose sharks were recorded in Slovenia and the Gulf of Trieste. Among these, the finding of the specimen in the Lagoon of Marano and Grado is unusual although there are reported cases of sixgill bluntnose sharks in rivers. An analysis of the available data on the bluntnose sixgill shark in the Adriatic Sea, obtained from different published papers, social media and other sources, was done to understand whether the occurrence of H. griseus in the northern Adriatic differs from other parts. A generalised linear model (GLM) approach revealed that larger specimens are more frequently sighted across the Adriatic Sea, while in the Northern Adriatic part, significantly smaller specimens (juveniles) were recorded in comparison to the Central and Southern parts. It seems that the bluntnose sixgill shark is not in conjunction with a common large shark decreasing trend across the whole Mediterranean Sea. [ABSTRACT FROM AUTHOR]

• Okadaic acid (OA) is the predominant DSP toxin in Slovenian mussels. • The period with the highest risk of human intoxication is from September to November. • OA is strongly associated with the abundance of Dinophysis fortii in seawater. • Introduction of the LC-MS/MS method has improved the management of aquaculture activities. This article presents the first results on shellfish toxicity in the Slovenian sea (Gulf of Trieste, Adriatic Sea) since the analytical methods for the detection of biotoxins (PSP, ASP, DSP and other lipophilic toxins) in bivalve molluscs were included in the national monitoring program in 2013. In addition to toxins, the composition and abundance of toxic phytoplankton and general environmental characteristics of the seawater (surface temperature and salinity) were also monitored. During the 2014–2019 study period, only lipophilic toxins were detected (78 positive tests out of 446 runs), of which okadaic acid (OA) predominated in 97 % of cases, while dinophysistoxin-2 and yessotoxins only gave a positive result in one sampling event each. The number of samples that did not comply with the EC Regulation for the OA group was 17 or 3.8 % of all tests performed, all of which took place from September to November, while a few positive OA tests were also recorded in December, April, and May. This toxicity pattern was consistent with the occurrence pattern of the five most common DSP-producing dinoflagellates, which was supported by the development of warm and thermohaline stratified waters: Dinophysis caudata, D. fortii, D. sacculus, D. tripos and Phalacroma rotundatum. The strong correlation (r = 0.611, p < 0.001) between D. fortii , reaching abundances of up to 950 cells L −1, and OA suggests that D. fortii is the main cause of OA production in Slovenian waters. Strong interannual variations in OA and phytoplankton dynamics, exacerbated by the effects of anthropogenic impacts in this coastal ecosystem, reduce the predictability of toxicity events and require continuous and efficient monitoring. Our results also show that the introduction of the LC-MS/MS method for lipophilic toxins has improved the management of aquaculture activities, which was not as accurate based on mouse bioassays. [ABSTRACT FROM AUTHOR]

The Mediterranean common dolphin (Delphinus delphis), considered to have been very common in the past, had undergone a dramatic decline across most of the basin by the end of 1970s. In the northern Adriatic Sea, one of the regions with most available historical information, the common dolphin is thought to have been the most common and abundant cetacean throughout most of the 20th century. However, by the end of 1970s, it had virtually disappeared from the region and is now considered generally absent from the entire Adriatic Sea.This contribution summarizes the occurrence of common dolphins in the Gulf of Trieste and provides a brief review of published records in other parts of the Adriatic Sea.Systematic boat surveys in the wider area of the Gulf of Trieste between 2002 and 2019 confirmed that the common bottlenose dolphin (Tursiops truncatus) is the only regularly occurring cetacean species in this area. Despite this, several records of common dolphins were documented in the Gulf of Trieste between 2009 and 2012, through sightings of live animals or recovery of dead stranded animals.Dorsal fin markings allowed the photo‐identification of some of these, suggesting that at least four different live individuals (three adults and one calf) occurred here in recent times. Most cases involved single adult individuals, but one included a mother‐calf pair that was temporarily resident in a port for several months, a behaviour atypical for this species. Photo‐identification showed that the presumed mother had previously been sighted in the Ionian Sea in Greece, over 1,000 km from the Gulf of Trieste, making this the longest documented movement for this species worldwide.At present, the common dolphin continues to be rare in the region. [ABSTRACT FROM AUTHOR]

This study aims to explore the spatial and temporal patterns in biomarker responses during early spring and late summer in Mytilus galloprovincialis using samples from two Adriatic Sea ecosystems between 2009 and 2012. The condition index was higher in September at all sampling sites and suggests that mussels can store energy during summer for wintertime spawning and survival through the winter. Over the entire study period, higher values of metallothioneins indicated sites with higher levels of heavy metals (Boka Kotorska Bay), while acetylcholine esterase activity was inhibited at the Gulf of Trieste. Genotoxicity was similar among sampling sites. We summarized biomarker responses in a stress index, IBRv2, and found that sampling sites in the Gulf of Trieste had lower stress levels while the highest stress levels were detected in the Boka Kotorska Bay. [ABSTRACT FROM AUTHOR]

On 3rd June 2018 three juvenile specimens of Polyprion americanus were captured in the Gulf of Trieste. The wreckfish is a long-lived deep-water demersal species characterized by an extended pelagic juvenile phase. The juvenile forms are recurrently recorded in the northern Adriatic and due to data deficiency for this species, original morphometric data are shown. The occurrence of P. americanus in the Gulf of Trieste is not a typical case of thermophilic species moving northward due to Mediterranean tropicalization, rather its recurrent appearance could be investigated for specific hydrological conditions coupled to its peculiar life span. [ABSTRACT FROM AUTHOR]

Physical and chemical data collected in three stations, with time series ranging from 1983, 1986 and 1989 to 2016, were analyzed in order to detect trends and frequency of occurrence of hypoxia events in bottom waters of the Gulf of Trieste (Adriatic Sea). The results of the analysis of 30-years data show a tendency toward increasing oxygen concentration in the bottom waters, nevertheless two hypoxic events were recorded during the summers of 2015 and 2016 even in a relatively shallow area of the Gulf. The spatial and temporal extent of these events was analyzed by coupling oceanographic surveys with automatic oceanographic measurements. During both summers, the area was characterized by high seawater temperature (up to 28.4 °C at the surface) and salinity (38.1 at the bottom) and a marked stratification of the water column, which prevented the mixing of oxygen-rich surface water with oxygen-poor deep water. The main contribution to oxygen depletion in the bottom waters was attributed to plankton respiration (54–61%) and to benthic oxygen consumption (39–46%), which exceeded the oxygen produced by planktonic and benthic microalgae and the one diffused from the overlying oxygenated water. These events of marked oxygen depletion in shallow coastal ecosystems are possibly favored by the positive temperature trend in bottom waters, coupled with the increase in riverine discharges in late spring, limiting vertical mixing and bottom water renewal. [ABSTRACT FROM AUTHOR]

Abundance and composition of the planktonic tintinnid ciliates were studied in the Gulf of Trieste (Northern Adriatic Sea, NE Mediterranean Sea) from July 1998 to July 2016. Tintinnids were collected biweekly-monthly from the LTER station C1 (200 m offshore, 17.5 m depth) at four depths (surface, 5 m, 10 m and 15 m). The maximum tintinnid abundance reached 4476 ind. L-1 at surface in February 2016. The tintinnid community comprised a maximum of 35 species and was dominated by the genera Stenosemella, Tintinnopsis, Codonellopsis, Salpingella and Eutintinnus. The most abundant species were Stenosemella nivalis, Tintinnopsis nana, Codonellopsis schabi, Salpingella rotundata and Eutintinnus apertus. We found a species-specific correlation with the abiotic factors considered, i.e., temperature and salinity. Temperature was positively correlated with S. rotundata and E. apertus and negatively with S. nivalis. Salinity was negatively correlated with the majority of the detected species. Agglutinated species presented winter maxima while hyaline species showed higher abundance in summer-autumn. Some key species were present over the whole period studied. Significant differences within the water column were not seen in the species composition, but were seen in the relative abundances of the same species at different depths. Stenosemella nivalis, S. ventricosa and Tintinnopsis beroidea can be considered as keystone species in the area and their possible loss can be seen as a signal of changes in the structure of the entire planktonic system. [ABSTRACT FROM AUTHOR]

We use multibeam sonar scanning of the seafloor and high-resolution sub-bottom sonar profiling to investigate pre-Holocene geomorphic features in the Gulf of Trieste that are visible in seafloor topography. We focus on two channel-like features, the Paleorižana and Paleoreka. Sub-bottom profiles and published core log data reveal that these features represent the transgressive surface at the boundary between Pleistocene continental and Holocene marine sedimentation. The geometry of the paleosurface, the architecture, and the acoustic facies of underlying sediment bodies clearly show that this surface represents an alluvial plain containing a moderate- to low-energy floodplain. The Paleorižana feature represents a meander belt with multiple meander scars and oxbow lakes, while the Paleoreka is a single, slightly sinuous channel river with well-developed levees. Geomorphic characteristics of the two rivers are replicated in the seafloor topography in astonishing detail, despite being draped by up to 10 m of Holocene marine sediments. We extract Paleoreka thalweg depths from sub-bottom profiles to construct a longitudinal channel profile, which runs approximately perpendicular to the main tectonic structures of the Gulf. We find no evidence of long-term mm-scale localized relative vertical tectonic movements which were previously inferred from repeated geodetic levelling surveys along the SW-NE oriented Slovenian coastline. We speculate that the geodetic data may instead indicate short-term interseismic deformation along the Slovenian coast, which would necessitate further investigation of tectonic activity and seismic hazard in the Gulf area. [ABSTRACT FROM AUTHOR]

A juvenile male of porbeagle (Lamna nasus) was caught in waters off Piran (Slovenia, northern Adriatic) on December 22, 2015. The specimen was accurately measured and weighed. Cephalopods and fish remains were found in its stomach contents. This is the first record of a porbeagle in the waters of Slovenia and in the Gulf of Trieste, and one of the few records up to date reported in the northern Adriatic Sea. The presence of this juvenile specimen arises a question whether the Adriatic Sea is a reproductive ground of this species. According to an older record from 1910, a female porbeagle with four embryos was caught on Ugljan Island, confirming the fact that porbeagles reproduced at least in the past in the Adriatic Sea. [ABSTRACT FROM AUTHOR]

Shallow and sheltered marine embayments in urbanized areas are prone to the accumulation of pollutants, but little is known about the historical baselines of such marine ecosystems. Here we study foraminiferal assemblages, geochemical proxies and sedimentological data from 1.6m long sediment cores to uncover ~500 years of anthropogenic pressure from mining, port and industrial activities in the Gulf of Trieste, Italy. From 1600 to 1900 AD, normalized element concentrations and foraminiferal assemblages point to negligible effects of agricultural activities. The only significant anthropogenic activity during this period was mercury mining in the hinterlands of the gulf, releasing high amounts of mercury into the bay and significantly exceeding the standards on the effects of trace elements on benthic organisms. Nonetheless, the fluctuations in the concentrations of mercury do not correlate with changes in the composition and diversity of foraminiferal assemblages due to its non-bioavailability. Intensified agricultural and maricultural activities in the first half of the 20th century caused slight nutrient enrichment and a minor increase in foraminiferal diversity. Intensified port and industrial activities in the second half of 20th century increased the normalized trace element concentrations and persistent organic pollutants (PAH, PCB) in the topmost part of the core. This increase caused only minor changes in the foraminiferal community because foraminifera in Panzano Bay have a long history of adaptation to elevated trace element concentrations. Our study underlines the importance of using an integrated, multidisciplinary approach in reconstructing the history of environmental and anthropogenic changes in marine systems. Given the prolonged human impacts in coastal areas like the Gulf of Trieste, such long-term baseline data are crucial for interpreting the present state of marine ecosystems. [ABSTRACT FROM AUTHOR]

Shallow and sheltered marine embayments in urbanized areas are prone to the accumulation of pollutants, but little is known about the historical baselines of such marine ecosystems. Here we study foraminiferal assemblages, geochemical proxies and sedimentological data from 1.6 m long sediment cores to uncover ~ 400 years of anthropogenic pressure from mining, port and industrial zones in the Gulf of Trieste, Italy. From 1600 to 1900 AD, element concentrations and foraminiferal assemblages point to negligible effects of agricultural activities. The only significant anthropogenic activity during this period is mercury mining in the hinterlands of the gulf, releasing high amounts of mercury into the bay and significantly exceeding today's Italian sediment quality guidelines (SQG) and the standards on the effects of trace elements to benthic organisms (ERL and ERM). Nonetheless, the fluctuations in the concentrations of mercury do not correlate with changes in the composition and diversity of foraminiferal assemblages due to its nonbioavailability. Intensified agricultural and maricultural activities in the first half of the 20th century caused slight nutrient enrichment and a minor increase in foraminiferal diversity. Intensified port and industrial activities in the second half of 20th century increased the normalised trace element concentrations and persistent organic pollutants (PAH, PCB) in the topmost part of the core, with solely Ni exceeding Italian SQG, ERL and ERM. This increase caused only minor changes in the foraminiferal community because foraminifera in Panzano Bay have a long history of adaptation to naturally elevated trace element concentrations. Our study underlines the importance of using an integrated, multidisciplinary approach in reconstructing the history of environmental and anthropogenic changes in marine systems. Given the prolonged human impacts in coastal areas like the Gulf of Trieste, such long term baseline data are crucial for interpreting the present state of marine ecosystems. [ABSTRACT FROM AUTHOR]

In this paper we investigated, for two years and with a bi-monthly frequency, how physical, chemical, and biological processes affect the marine carbonate system in a coastal area characterized by high alkalinity riverine discharge (Gulf of Trieste, northern Adriatic Sea, Mediterranean Sea). By combining synoptic measurements of the carbonate system with in situ determinations of the primary production ( 14 C incorporation technique) and secondary prokaryotic carbon production ( 3 H-leucine incorporation) along a river–sea gradient, we showed that the conservative mixing between river endmember and off-shore waters was the main driver of the dissolved inorganic carbon (DIC) distribution and seasonal variation. However, during spring and summer seasons also the influence of biological uptake and release of DIC was significant. In the surface water of June 2012, the spreading and persistence of nutrient-rich freshwater stimulated the primary production (3.21 μg C L − 1 h − 1 ) and net biological DIC decrease (− 100 μmol kg − 1 ), reducing the dissolved CO 2 concentration and increasing the pH T . Below the pycnocline of August 2012, instead, an elevated bacterial carbon production rate (0.92 μg C L − 1 h − 1 ) was related with net DIC increase (92 μmol kg − 1 ), low dissolved oxygen concentration, and strong pH T reduction, suggesting the predominance of bacterial heterotrophic respiration over primary production. The flux of carbon dioxide estimated at the air–sea interface exerted a low influence on the seasonal variation of the carbonate system. A complex temporal and spatial dynamic of the air–sea CO 2 exchange was also detected, due to the combined effects of seawater temperature, river discharge, and water circulation. On annual scale the system was a sink of atmospheric CO 2 . However, in summer and during elevated riverine discharges, the area close to the river's mouth acted as a source of carbon dioxide. Also the wind speed was crucial in controlling the air–sea CO 2 exchange, with strong Bora events (a typical ENE wind of the Gulf of Trieste) that drastically increased the absorption (− 32.2 mmol m − 2 day − 1 ) or the release (5.34 mmol m − 2 day − 1 ) of carbon dioxide. [ABSTRACT FROM AUTHOR]

Bougainvillia triestina was described by Hartlaub in 1911 from specimens collected in the Gulf of Trieste (North Adriatic, Italy). Two years later, after re-examination of the same specimens, Neppi & Stiasny (1913) concluded that these were in fact juvenile medusae of Bougainvillia autumnalis (now synonymized with Bougainvillia muscus). Based on unique morphological traits and genetic analyses (16S rRNA, 18S rRNA, COI) of specimens of different stages recently collected in the shallow and enclosed coastal area of Ploče Harbour and Mali Ston Bay (South Adriatic, Croatia), we can confirm, 100 years after its first description, B. triestina as a valid, distinct species, clearly distinguishable from B. muscus (Allman 1863). Based on its occurrence in the Adriatic Sea, B. triestina seems to prefer productive coastal areas with a wide range of temperatures and salinities. Therefore, we expect that this species inhabits other coastal areas of the Mediterranean Sea as well as those of other seas and oceans. Given this, it is probable that in previous investigations some records of B. triestina were incorrectly attributed to B. muscus. [ABSTRACT FROM AUTHOR]

In the marine environment, underwater noise is one of the most widespread input of man-made energy. Recently, the European Commission has stressed the necessity of establishing threshold levels as a target for the descriptor 11.2.1 “Continuous low frequency sounds” in the Marine Strategy Framework Directive (MSFD). In 2012, a monthly underwater noise monitoring programme was conducted in the Gulf of Trieste (Northern Adriatic Sea, Italy); the collected acoustic samples (frequency range: 10–20,000 Hz) were analysed in the 1/3 octave bands. The stations have been further clustered following the 63 and 125 Hz bands noise levels. Average SPL levels resulted similar to those previously computed for proximate areas, indicating that the Adriatic Sea sub-region experiences high noise pressure in the marine waters. In its turn this claims for a scientific and technical international cooperation, as requested by the EU programme. No seasonal variation in local noise levels has been found. [ABSTRACT FROM AUTHOR]

The effect of short and long-term induced anoxia on a benthic nematode community and its potential for recovery after reoxygenation were investigated in an in situ experiment on a silty-sand bottom in the Gulf of Trieste, the northern Adriatic Sea. Anoxia was created artificially by three underwater benthic Plexiglas chambers at a depth of 24 m. Treatments lasted for 2, 23 and 307 days. Control samples (Normoxia) were taken on 3 (Normoxia 1) and 25 (Normoxia 2) August 2010 outside the chambers (4–5 m further). After opening the chambers, recovery cores were taken after 7 days (Anoxia 2D), 30 days (Anoxia 23D) and 90 days (Anoxia 307D). Our results revealed that short-term anoxia (Anoxia 2D) did not affect nematode total density and diversity, community structure and their vertical distribution in the sediment. However, total and vertical nematode density, species richness and diversity decreased at 23 days and decreased further at 307 days anoxia. Some nematode species like Metalinhomoeus effilatus, Paralinhomoeus caxinus and Terschellingia longicaudata even survived at 307 days anoxia treatment. Our results also demonstrated that nematode community exposed to 23 days anoxia did not recover after 30 days sediment reoxygenation but, a full recovery was observed after 90 days for nematode community exposed to 307 days anoxia. Feeding type contribution (functional aspect) of the nematode community also changed at the anoxia treatments and during the recovery process. This change was most drastic at the Anoxia 23D and 307D treatments. At both Normoxia and Anoxia 2D treatments, selective deposit feeders (1A), non-selective deposit feeders (1B) and epistrate (diatom) feeders (2A) nematodes were observed in the dominant nematode community. Epistrate feeders disappeared from in the Anoxia 23D treatment epistrate and also selective deposit feeders did not belong to the dominant nematode species in the Anoxia 307D treatment. After the recovery process, epistrate feeders and selective deposit feeding nematodes reappeared again amongst the dominant nematode species after 30 and 90 days of recovery, respectively. [ABSTRACT FROM AUTHOR]

The distribution of the endemic brown alga Fucus virsoides was assessed along the northern Adriatic coastline. A high-resolution geographic information system database was created using visual census methods to identify the presence and abundance of algae, including the geomorphology of the substrate. Samples of F. virsoides were collected for analysis of the quantitative spatial distribution. The abundance of F. virsoides was related to several environmental variables, including the relative exposure index (REI). The results support the hypothesis that the distribution of F. virsoides in the Gulf of Trieste is influenced mainly by the stability of mediolittoral substrata, wave exposure and the vicinity of freshwater inputs. Populations of this species are widespread in the Gulf of Trieste. Many of them were found growing inside small harbours or along a boatyard, where fluctuations in salinity and nutrient concentrations are frequent. Therefore, we conclude that F. virsoides cannot be considered an ecological indicator for seawater pollution nor for climate change, since it is subjected naturally to high pollution levels and environmental variability. [ABSTRACT FROM AUTHOR]

In our research the concentrations of major and minor elements were determined in natural sea salts from the Sečovlje salina (Piran salts, Slovenia) and compared to those of selected samples of commercially available unrefined salts with different geographical origins (Croatia, Austria, Italy, Portugal, India, and Pakistan). In the case of major element contents such as sodium (Na), iron (Fe), aluminum (Al), manganese (Mn), and titanium (Ti) many similarities were observed among the analysed salt samples. On the other hand, Piran salts are characterized by lower silicon (Si) values. Among the salts from the Sečovlje salina, the salt with the trade name Piran salt has a higher Mg content while Flower of salt has a lower concentration of calcium (Ca). In Slovenian samples the majority of trace element values were lower than 0.5 μg g-1 which was comparable to the results from commercially available unrefined salts. The salt composition differences observed indicate area-specific signatures related to geographic origin and diverse salt production processes. The quality of the studied salt samples is in accordance with standards established by the Codex Alimentarius Commission and the Piran salts are also suitable regarding issues of national food control. [ABSTRACT FROM AUTHOR]

Combined in situ and laboratory studies were conducted to document the effects of anoxia on the structure and functioning of meiobenthic communities, with special focus on harpacticoid copepods. In a first step, anoxia was created artificially by means of an underwater chamber at 24m depth in the Northern Adriatic, Gulf of Trieste (Mediterranean). Nematodes were found as most abundant taxon, followed by harpacticoid copepods. While nematode densities were not affected by treatment (anoxia/normoxia) or sediment depth, these factors had a significant impact on copepod abundances. Harpacticoid copepod family diversity, in contrast, was not affected by anoxic conditions, only by depth. Ectinosomatidae and Cletodidae were most abundant in both normoxic and anoxic samples. The functional response of harpacticoid copepods to anoxia was studied in a laboratory tracer experiment by adding 13C pre-labelled diatoms to sediment cores in order to test (1) if there is a difference in food uptake by copepods under normoxic and anoxic conditions and (2) whether initial (normoxia) feeding of harpacticoid copepods on diatoms results in a better survival of copepods in subsequent anoxic conditions. Independent of the addition of diatoms, there was a higher survival rate in normoxia than anoxia. The supply of additional food did not result in a higher survival rate of copepods in anoxia, which might be explained by the presence of a nutritionally better food source and/or a lack of starvation before adding the diatoms. However, there was a reduced grazing pressure by copepods on diatoms in anoxic conditions. This resulted in a modified fatty acid composition of the sediment. We concluded that anoxia not only impacts the survival of consumers (direct effect) but also of primary producers (indirect effect), with important implications for the recovery phase. [ABSTRACT FROM AUTHOR]

Abstract: By measuring a broad suite of physical, chemical, and biological parameters coupled with experiments on grazing efficiency of mesozoo-, microzoo- and heteronano-plankton we were able to depict the seasonal trophic status of the pelagic system in the Gulf of Trieste over a period of 8 years from 1998 to 2005. In winter and spring, primary production exceeded respiration, the autotrophic fraction biomass was higher than the heterotrophic biomass. Moreover, predation on microphytoplankton and autotrophic nanoplankton largely structured the ecosystem and bacterial carbon production accounted for <50% of primary production. The ratio of primary production/respiration was higher than 1 in winter and spring suggesting that pelagic ecosystem was autotrophic whereas in summer and in autumn the ratio was lower than 1 suggesting a shift towards net heterotrophic status. Carbon export was possible in winter and in autumn, and the few data from the sediment trap supported the theoretical rates. Thus since spring most of the C fixed by photosynthesis remained segregated in the surface layer and possibly it was exported to the bottom through grazer fecal pellets. In summer the system was dominated by heterotrophic picoplankton, which showed the highest production rate. In this scenario we hypothesize that the DOC produced during the winter-spring period can sustain a high and active bacterial biomass that is the primary energy source for the whole system. Picoplankton communities were heavily grazed by microzooplankton and heteronano-plankton, moreover predation rates of mesozooplankton on microzooplankton were particularly high in summer. Despite the high variability typical of the coastal areas, the pelagic ecosystem during these 8 years has shifted seasonally from a nutrient-excited state (winter–spring) to a background state (summer–autumn) as it has been observed from open-ocean ecosystem. Understanding the dynamic and the magnitude of this variability-shift is rather compelling in order to give guidance in managing the Gulf area in the context of CO2 sequestration mitigation programs (carbon export downward flux) as well as for fishery economy. [Copyright &y& Elsevier]

Abstract: Abundance and composition of microzooplankton were studied over a 15 years period (from March 1986 to December 1990 and from July 1998 to December 2010) in the Gulf of Trieste (Adriatic Sea, NE Mediterranean Sea). Sampling was conducted biweekly-monthly at the surface at the historical station C1, 200 m offshore (bottom depth 17.5 m). Aloricate ciliates dominated in both periods (median 117 and 243 ind. L−1 in the first and second period respectively) while tintinnids were more abundant in the first period (median 55 ind. L−1 vs 16 ind. L−1). For heterotrophic dinoflagellates there are no data during the first period and in the second one they represented the second major group. Micrometazoans remained almost constant over time. In the first period all microzooplankton groups showed a maximum in April, while in the last period the peak has shifted to September. This is particularly evident for both aloricate ciliates and micrometazoans. Tintinnids, that in the past had the absolute maximum in spring, in the second period maintained the only, lower peak in October. Tintinnids in the first period were constituted by 27 species and dominated by the genera Tintinnopsis, Stenosemella and Salpingella. In the last 10 years we registered a dramatic decrease in abundance, paralleling an increase in species (40) with some “new entries” as well as the almost complete disappearance of genera Helicostomella, Favella, Coxiella and Steenstrupiella. The observed changes of the seasonal dynamics of microzooplankton abundance, as well as of the tintinnids composition over the long period considered in our study, might suggest a climatic forcing together with the known anthropogenic oligotrophication of the entire North Adriatic. [Copyright &y& Elsevier]

Abstract: The seasonal variability of the carbonate system in the waters of the Gulf of Trieste (GoT) was studied at PALOMA station from 2008 to 2009, in order to highlight the effects of biological processes, meteorological forcings and river loads on the dynamics of pHT, CO2 partial pressure (pCO2), dissolved inorganic carbon (DIC), carbonate ion concentration , aragonite saturation state (ΩAr) and total alkalinity (A T). During winter, low seawater temperature (9.0 ± 0.4 °C) and a weak biological activity (−10.7 < AOU < 15.7 μmol O2 kg−1) in a homogeneous water column led to the lowest average values of pCO2 (328 ± 19 μatm) and ΩAr (2.91 ± 0.14). In summer, the water column in the area acted as a two-layer system, with production processes prevailing in the upper layer (average AOU = −29.3 μmol O2 kg−1) and respiration processes in the lower layer (average AOU = 26.8 μmol O2 kg−1). These conditions caused the decrease of DIC (50 μmol kg−1) and the increase of ΩAr (1.0) values in the upper layer, whereas opposite trends were observed in the bottom waters. In August 2008, during a hypoxic event (dissolved oxygen DO = 86.9 μmol O2 kg−1), the intense remineralisation of organic carbon caused the rise of pCO2 (1043 μatm) and the decreases of pHT and ΩAr values down to 7.732 and 1.79 respectively. On an annual basis, surface pCO2 was mainly regulated by the pronounced seasonal cycle of seawater temperature. In winter, surface waters in the GoT were under-saturated with respect to atmospheric CO2, thus acting as a sink of CO2, in particular when strong-wind events enhanced air–sea gas exchange (FCO2 up to −11.9 mmol m−2 d−1). During summer, the temperature-driven increase of pCO2 was dampened by biological CO2 uptake, as consequence a slight over-saturation (pCO2 = 409 μatm) turned out. River plumes were generally associated to higher A T and pCO2 values (up to 2859 μmol kg−1 and 606 μatm respectively), but their effect was highly variable in space and time. During winter, the ambient conditions that favour the formation of dense waters on this continental shelf, also favour a high absorption of CO2 in seawater and its consequent acidification (pHT decrease of −0.006 units during a 7-day Bora wind event). This finding indicates a high vulnerability of North Adriatic Dense Water to atmospheric CO2 increase and ocean acidification process. [Copyright &y& Elsevier]

Abstract: To obtain more insight into the effects of severe forcing factors on a shallow coastal system, the elemental stoichiometry and the availability and partition of nitrogen, phosphorus and carbon in dissolved and particulate pools were assessed during events of particularly strong inputs of freshwater, high salinity anomalies, wind storms, algal blooms and elevated heterotrophic respiration processes. The research is based on data collected in the Long Term Ecological Research station of the Northern Adriatic Sea (Gulf of Trieste), from January 1999 to December 2010. During all considered events, stoichiometric ratios were higher than Redfield, due to an excess of carbon and nitrogen in relation to phosphorus. The particularly intense meteorological and biological events considered in this study altered the abundance, the relative availabilities of C, N and P and the stoichiometric ratios in different directions. Freshwater inputs and phytoplankton blooms caused a rise in the ratio between dissolved organic carbon and phosphorus, in N:P and C:P in the particulate compartment and, in the case of high freshwater only, in dissolved inorganic N:P, while the opposite was observed during events dominated by ingression of south-eastern waters and heterotrophic processes, when stoichiometric ratios decreased. Strong wind events, which are mainly due to north-easterly winds, did not seem to significantly modify the biogeochemical properties in the bottom layer. [Copyright &y& Elsevier]

Abstract: Freshwater and nutrient discharges by rivers were analysed in the northeastern Adriatic continental shelf from 1998 to 2008, in order to assess their role in the biogeochemistry of this coastal zone, as well as their potential future changes due to the effects of climate variability and anthropogenic pressure. River water loads (up to 6.05 km3 yr−1) and transport of nutrients (up to 13,200 t N yr−1 for TN, 86 t P yr−1 for TP and 12,400 t Si yr−1 for Si(OH)4) were high from 1998 to 2002, but they decreased by over 70% during the driest years 2003, 2005, 2006 and 2007. The precipitation in the surrounding continental region (average of 1371 mm yr−1) is the major forcing that regulates the runoff in this area, with peaks in early spring and autumn that are associated respectively to negative phases of Mediterranean Oscillation index and positive phases of West Mediterranean Oscillation index. This finding, together with the minor contribution of snowmelt in early spring (up to 3.2·10−5 kg m−2 s−1), indicates that the dynamics of the natural water cycle still overtake in this coastal zone the effects of anthropogenic usage of continental waters. During the last four decades, the northeastern Adriatic continental shelf has been subjected to an increasing pressure due to a high river transport of nitrogen and, currently, only a deep phosphorus deficiency in total (TN/TP = 49–405) and inorganic (DIN/PO4 = 37–418) river nutrient pools prevents its severe eutrophication. By contrast, the decrease of river loads of nutrients from 2003 to 2007 indicates that recurrent water crisis might significantly lower the trophic level in this coastal zone in the future. In this perspective, other allochthonous sources of nutrients, like sewage loads, atmospheric deposition and benthic fluxes might become more important for their balance, with possible implications on the structure of this ecosystem. [Copyright &y& Elsevier]

The purpose of this preliminary study was to define the vertical migration pattern in the dinoflagellate community in the shallow coastal sea. Migrations were followed in an area of mussel farming, through two 24-hour samplings, first during mixed and second during stratified water column conditions. Despite variable physical environment we were able to follow vertical migrations of some autotrophic dinoflagellate species in the period of stratified water column. The results also suggest that Heterocapsa sp. may preserve its vertical migration pattern also under mixed conditions. Migrations were observed also for Dinophysis sacculus that can cause DSP problems in the area. [ABSTRACT FROM AUTHOR]

Purpose: The Gulf of Trieste (northern Adriatic Sea) is an example of a coastal environment contaminated with mercury (Hg). Contamination is a consequence of nearly 500 years of activity at the Idrija Mine (western Slovenia), which is the second largest Hg mine in the world. Oxygen depletion can be common in the Gulf of Trieste due to late summer stratification of the water column and accumulation of labile organic matter. Since changing redox conditions can have an impact on Hg transformations, we studied the effect of oxygen depletion, in parallel with sulphide, iron (Fe), manganese (Mn), fluorescent dissolved organic matter (FDOM) and nitrogen (N) and phosphorus (P) availability, on total Hg and methylmercury (MeHg) fluxes from sediments. Materials and methods: Pore water concentrations and benthic fluxes of total dissolved Hg and MeHg were studied in situ and in microcosm laboratory experiments using flux chambers encompassing three different stages: oxic, anoxic and reoxidation. Results and discussion: Our experiments showed that in the oxic stage there were small effluxes of MeHg to the water column, which increased in the anoxic stage and dropped rapidly in a subsequent reoxic stage, showing influx. Our results support the hypothesis that MeHg desorption from reduced metal hydroxides under anoxic conditions, and co-precipitation with Fe-oxides and MeHg demethylation in the reoxidation stage, may play a major role in determining MeHg benthic fluxes. For Hg and MeHg, it appears that there is little relationship between their pore water distribution and flux and that of FDOM, i.e. humics. Conclusions: The results indicate that there was no significant difference in Hg and MeHg pore water levels and their benthic fluxes between the contaminated northern and central parts of the Gulf of Trieste and the pristine southern part. This suggests that shallow and stratified coastal marine environments, in general, represent areas with a risk of high benthic release of toxic MeHg. [ABSTRACT FROM AUTHOR]

The state of knowledge on marine alien molluscan species from the Gulf of Trieste and neighbouring areas is presented based on a critical review of records compiled from an extensive literature survey and from unpublished data obtained from 2006 to 2011, and enriched by older material preserved in private collections. Based on the IUCN definition of 'alien', 13 valid alien molluscan taxa (3 Gastropoda and 10 Bivalvia) are reported here, for each of which the following information (collected up to August 2011) is provided: published and unpublished records from the coastal and offshore territorial seawaters of the Gulf of Trieste and neighbouring areas, including lagoons; establishment status; vector(s) of introduction. The area was characterized by the presence of eight established alien species, while another four were considered as casual and one was, with caution, considered not established. Specimens of Anadara transversa (Say, 1822) and Limnoperna securis (Lamarck, 1819) are first reported here from the Gulf of Trieste, thus reaching the extreme northern point of the Mediterranean Sea. Old distribution data on Mercenaria mercenaria (Linnaeus, 1758) and Mya arenaria Linnaeus, 1758 are considered unreliable, also according to the recent literature. Accurate analysis of bibliographic data as well as re-identification of specimens preserved in private collections or collected from the same published sampling sites led to the exclusion of Assiminea grayana Fleming, 1828 and Conomurex persicus (Swainson, 1821)from the resident fauna of the Gulf of Trieste. Concerning Arcuatula senhousia (Benson in Cantor, 1842), its first record from Slovenia came from bibliographic misreading, so that the original record of this bivalve from the area is considered more recent. Finally, natural dispersal accounts for 46% of the plausible vectors of introduction, while shipping/maritime transport and aquaculture for 23%. [ABSTRACT FROM AUTHOR]

Abstract: The growth, activity and structure of a marine plankton assemblage from the Gulf of Trieste (NE Adriatic Sea) were monitored in a short-term mesocosm experiment (25L) in order to investigate the influence of phosphorous availability on the production and utilization of organic matter. The coastal community, dimensionally selected (<200μm), was grown under different P-concentrations. The results obtained from the nutrient enriched enclosures highlighted the microbial food web potential in high productivity systems: the phytoplankton community grew to a bloom-like state and resulted particularly productive enhancing the development of the prokaryotic population (especially of its active fraction). Glucidic exoenzymes operated at high hydrolysis rates in order to recycle extracellular carbohydrate/exudates produced by the abundant phytoplankton community. Intense prokaryotic production, directed prevalently to replication rather than to biomass production, increased the density of prokaryotic cells on levels that particularly favoured virus proliferation, acting thus as feedback control on the bacterial population. Different P concentrations also strongly influenced the structure of the bacterial community (either directly or indirectly) analyzed through denaturing gradient gel electrophoresis (DGGE), by selecting two diverse assemblages at the end of the experiment. Conversely to high N:P ratios observed throughout the year in the Northern Adriatic Sea, our study simulated a phosphorous-balanced condition and pointed out how nutrient limitation affects the entire microbial plankton community, reducing the trophic status of the environment through the control of phytoplankton production. [ABSTRACT FROM AUTHOR]

Culturable vibrios were isolated from seawater collected during an annual sampling study performed along the Gulf of Trieste coast (Northern Adriatic Sea), and conventional culturing and identification methods were used to investigate the presence of Vibrio parahaemolyticus. Biochemically selected Vibrio strains were subjected to phenotypical identification performed using Alsina's scheme, API 20E and API 20NE. PCR and sequence analysis of the 16S rRNA gene and detection of the species-specific toxR and tlh genes were carried out on strains presumptively identified as V. parahaemolyticus and on a set of unidentified strains to confirm biochemical characterizations. In addition, PCR assays targeting the virulence genes, tdh and trh, were carried out to detect pathogenic strains. PCR results were compared with phenotypic characterizations to evaluate the accuracy of the biochemical methods applied. False-negative identifications were obtained by all phenotypic-based procedures, while API 20E yielded only one false positive. Because the amplification of the 16S rRNA gene produced uncertain results, toxR and tlh gene detections were necessary to confirm the biochemical identifications. Finally, molecular characterization demonstrated the presence of V. parahaemolyticus trh-positive strains and underlined the difficulty in the recognition of the pathogenic environmental organism using conventional methods. [ABSTRACT FROM AUTHOR]

Abstract: Although the temporal and spatial variability of virioplankton in the northernmost part of the Adriatic Sea has been repeatedly explored suggesting that viruses constitute an extremely dynamic component of the plankton community and hypothesizing their importance in marine food webs and mucilage events, there is still no information about viral replication rates. Hence, the contribution of viruses to bacterial mortality and the cycling of organic matter in this part of the Adriatic basin are still not fully comprehended. Assessment of the role of viral lysis requires a robust means of estimating viral production. Since, up to now, none of the available methods evolved to a state of a standard yet, in this preliminary study 3 different experimental approaches were simultaneously assayed (viral production estimated by radiotracer incorporation method [TdR], dilution technique for the estimate of viral production in already infected bacteria [DIL] and serial dilution method in manipulated phage-host assemblage [SER]). The present study provided the first evidence of viral production rates in this study area, that resulted in comprising between ∼3.5–15×108 viruses L−1 h−1 and critically faced up the results obtained by different techniques with the consideration that they suffer from different biases. Based on TdR and DIL viral proliferation estimates, viral lysis was responsible for the loss of 54 to 95% of the bacterial standing stock, while the viral-induced mortality by SER (325%d−1) was likely consistently overestimated. These results indicate that viral lysis is a significant factor for prokaryotic mortality suggesting its implication as an important pathway for the cycling of dissolved organic matter in the Gulf of Trieste. [Copyright &y& Elsevier]

Abstract: Drilling predation is one of the most studied biotic interactions in the fossil record and potentially controls biodiversity, but its history may be confounded by natural patchiness across environments. This aspect has been inconsistently evaluated. The current study contributes to our understanding of drilling predation in the Northern Adriatic, which has been previously classified as a low-predation setting, and examines the roles of environment, patchiness, and ecology of prey organisms in modern seas. Nearly 49,000 molluscs from two intertidal and six sublittoral bulk samples along a transect in the Gulf of Trieste were analysed for drill frequency (DF) and prey effectiveness (PE), a measure of prey''s ability to resist predatory attacks. DF across all samples was 20.6%, but varied between the intertidal (1.4%) and sublittoral (27.4%). Among the latter, DF differed between the delta foreset beds (18.1%) and level bottom muds and sands (∼28% each). PE was low in the intertidal (1.1%) and sublittoral (4.5%). Overall DF and PE among the three mud samples varied by nearly 10%, while that within the two sand samples varied little; however, significantly different DFs were observed only among the families Nuculidae, Galeommatidae and Corbulidae in level bottom mud and Cerithiidae in level bottom sand samples. Only Corbulidae displayed significant variation in PE among level bottom mud samples (16.5–43.7%). PE varied significantly between level bottom sand samples only within the families Cerithiidae and Trochidae. Suspension-feeding bivalves and gastropods had the highest DFs (24.3% and 39.1%, respectively), and the value of epifaunal bivalves (32.0%) was nearly twice as high as that of infaunal bivalves (17.9%). DFs of cementing (43.0%) and byssate (27.0%) bivalves were higher than that of recliners (9.9%). Considering their cryptic life habits, parasitic gastropods (20.3%) and commensal bivalves (40.6%) had exceptionally high DF. For each ecological category, PE was highest on suspension-feeding (11.1%), infaunal (15.8%) and cementing (10.5%) bivalves, and on parasitic gastropods (11.9%). DF did not correlate with diversity indices or predator abundance in the sublittoral; therefore, drilling predation probably does not control diversity on the local scale here. DFs support paleoecological theory relating predation to changes in ecological guilds through the Phanerozoic. DFs were highest on suspension feeders, parasites and sessile prey, and were lowest on predators, recliners, and endobenthic molluscs. While cementation likely reduces bivalve susceptibility to durophages, it apparently does not to impede drilling predators. Finally, DF did not vary across size classes in any species examined except Venerupis rhomboides, where the smallest fraction was drilled more often. Additionally, as the proportion of large individuals in our samples was small, disparities in DF across size classes probably did not influence our results. With respect to predation intensity the relatively high DF in the sublittoral, as well as high DF and PE for various taxa and guilds, places the Northern Adriatic Sea among typical Cenozoic shelf environments. [Copyright &y& Elsevier]

Abstract: This paper reports the rate of change of mesozooplankton biomass on seasonal, inter-annual and decadal time scale in the Gulf of Trieste (NE Mediterranean, Northern Adriatic). We measured variability in mesozooplankton dry weight (mg DW m−3), organic carbon and nitrogen contents of the DW in relation to mesozooplankton taxonomic structure and some environmental parameters. The study is based on data obtained from mesozooplankton samples collected monthly by a vertical WP2 net (200 µm) from January 1986 to September 2005 at one monitoring station, a coastal site in the Gulf of Trieste. We considered mesozooplankton DW in relation to copepods, phytoplankton taxonomic structure, water temperature and North Atlantic Oscillation. For further analyses we counted also on data for DW for the period 1972–1980, monthly data for organic carbon (mg C m−3) and nitrogen contents (mg N m−3) of the DW for the period 1991–2005, determined by a CHN Elemental Analyzer. We explored statistically our high temporal resolution time series data picking out the main features: seasonal components and trends. Mesozooplankton DW ranged from only 1 mg m−3 (January 1977) to 95 mg m−3 (March 1990) in the coastal ecosystem of the Northern Adriatic during the period 1972–2005. The annual cycle of the DW was found to be bimodal with maximum in late winter–spring and a weaker one in late summer. Maximum DW were regularly recorded when Copepods prevailed the mesozooplankton community structure. Similarly, high organic carbon and nitrogen contents were detected when copepods dominated, although wide-ranging on a seasonal scale. Irregular intra- and inter-annual fluctuations were typical mostly during the 1990s. Mesozooplankton DW sharply shifted since 2001–2002 to the level exceeding the observed one during the regime of the 1980s. Our results indicate substantial changes in the seasonal timing of mesozooplankton DW, which together with decadal inter-annual fluctuations match significantly with shifts in copepods, phytoplankton taxonomic structure, temperature and NAO index. The discussed zooplankton descriptors (DW, C and N contents and C:N ratio) being to a certain degree predictive of phyto- and mesozooplankton composition, in essence might foretell the phenological response of plankton communities to environmental changes in the coastal ecosystem, including climate change. [Copyright &y& Elsevier]

Abstract: Carbon and nitrogen stable isotope ratios of particulate organic matter (POM) were studied approximately weekly during spring and summer 2003 and 2004 in the Gulf of Trieste (northern Adriatic Sea) in order to track the temporal variations and differences between two years. In parallel, particulate organic carbon (POC) and particulate nitrogen (PN), phytoplankton biomass (chlorophyll a), and N and P nutrients were monitored. All studied parameters, especially N and P nutrients and chlorophyll a, showed higher concentrations and larger variability in spring 2004. As a consequence the macroaggregates were produced in late spring 2004. The C and N isotope composition of POM was not directly linked to phytoplankton biomass dynamics. The δ 13CPOC values covaried with temperature. In 2004, δ 13CPOC variations followed the δ 15NPN values as well as the δ 13CDIC values which were probably more dependent on the photosynthetic use of 12C. Variations in δ 15NPOM values were most probably the consequence of variations in N nutrient sources used in phytoplankton assimilation. The significant correlation between δ 15NPN values and nitrate concentrations in 2004 implies intense nitrate assimilation in the presence of higher nitrate concentration. This suggests nitrate as the key nutrient in the »new primary production«, later producing macroaggregates with a mean δ 13C and δ 15N values of −19‰ and 5‰, respectively. A low fractionation factor ε, <1‰, lower than that reported in other marine and lacustrine systems, was found probably to be a consequence of distinct phytoplankton species, i.e. several classes of autotrophic nanoflagellates, and specific growth conditions present in the Gulf of Trieste. The tentative use of C isotope composition of POM revealed a higher contribution of allochthonous organic matter in 2004 compared to 2003 due to higher riverine inflow. [Copyright &y& Elsevier]

Abstract: Hexaplex trunculus (Linnaeus, 1758) is one of the most abundant and widespread muricid gastropods in the Northern Adriatic Sea, but relatively little is known about the feeding ecology of this predator. We examined the activity of H. trunculus on a sublittoral mussel bed at 24 m depth through in situ time-lapse observations and bulk samples. The camera photographed a 0.25 m2 section of the mussel bed at 6-min intervals for ~23 h. Photos were examined frame-by-frame for gastropod movement and activities, especially interactions between H. trunculus and Mytilus galloprovincialis (Lamarck, 1819). Our survey indicates high activity-levels of H. trunculus on the sea floor: all gastropods made minor movements, most made major movements, and most left the field of view during the study-interval. On average, individuals remained stationary for only 7.3 h. Two predation attempts on Mytilus involving conspecific competition were documented, and one Hexaplex was consuming a mussel at the onset of the deployment. Additionally, 487 M. galloprovincialis from four diver-taken 0.25 m2 quadrates were measured and examined for traces of marginal chipping and drilling predation. Mytilus from surface samples ranged from 11.1 mm to 95.5 mm in length, and one of the four samples had a significantly different average shell length from the others. 114 H. trunculus were collected and measured. Hexaplex ranged from 22.1 mm to 86.1 mm and the mean shell length did not differ among samples, though they were overwhelmingly medium and large. Predation frequency (the ratio of successfully preyed upon bivalves to the total number of bivalves sampled) is high at the studied site (>55%), and large gastropods preferred a chipping mode of predation to drilling, supporting earlier laboratory studies showing a preference for M. galloprovincialis and this predation strategy. Prey effectiveness (the ratio of failed predatory attacks to total predatory attacks) is also high (63.8%), and no evidence of a size refuge was found. Feeding in H. trunculus is highly facultative, calling for caution when using drill holes to estimate predation intensities; whenever possible, traces of multiple predation modes should be considered. [Copyright &y& Elsevier]

Abstract: Monthly sediment sampling was carried out from February 1999 to December 2001 at a 21-m deep station. Benthic diatom biomass and meiobenthic abundance were estimated together with abiotic parameters (PAR irradiance, temperature, salinity and dissolved oxygen). During the three-year study average microphytobenthic abundance (ABU) and biomass (BIOM) were 4.7±2.6×104 cell cm−3 and 14.3±8.1 µg C cm−3, respectively, while the mean meiofaunal abundance was 923±210 ind 10 cm−2. The microphytobenthic community was mainly composed of Bacillariophyceae (99.3%) with a smaller percentage of phytoflagellates (0.7%). Among diatoms 39 genera were observed with a total of 110 taxa and 100 species. The main benthic diatom genera were Navicula, Paralia, Nitzschia and Diploneis. A total of 18 meiobenthic taxa were detected: 7 taxa belonged to permanent meiofauna (Nematoda, Copepoda Harpacticoida and their nauplius stages, Kinorhyncha, Turbellaria, Gastrotricha, Ostracoda and Acarina). The remaining 11 taxa belonged to temporary meiofauna (juvenile macrofauna: Polychaeta, Cumacea, Amphipoda, Isopoda, Nemertea, Decapoda, Sipunculida, Ophiurida, Gastropoda, Bivalvia and Cnidaria). Positive correlations between PAR and the biomass of the major diatom genera were revealed. Temperature did not seem to influence the microphytobenthic community as a whole, although we found statistically significant correlation between temperature and the genera Nitzschia and Amphora. Salinity showed significant positive correlation only with the genus Pleurosigma, in contrast, dissolved oxygen did not seem to affect the microalgal community. The major meiofaunal taxa were not correlated with abiotic variables, but were positively correlated with most diatom genera. Paralia was negatively correlated with the three main meiofaunal taxa. The three-point moving average applied to our biotic data allowed us to better the signal without the background noise which hid the actual variations of the studied communities. Applying the three-point moving average to the main taxa, it resulted that microphyto- and meiobenthos were in phase. The principal component analysis (PCA), constructed considering both biotic and abiotic variables, accounted for 58% of the total variance. PC1 axis explained 39.74% of the total variance and was correlated with Navicula, Diploneis and Nitzschia. PC2 axis explained 18.40% of the remaining variance and was correlated with Copepoda, Paralia and PAR. In contrast to 1999 and 2001, a mucilage event occurred in 2000, which resulted in the formation of a false bottom and a decrease in the abundance of microphyto- and meiobenthos. [Copyright &y& Elsevier]

The Adriatic Sea is vulnerable to pollution due to its low bathymetry, intense industrial activity, and tourism. In this context, a good depuration plant activity could play a key role for the maintenance of a good environmental quality. In the framework of the AdSWiM project, "Managed use of treated urban wastewater for the quality of the Adriatic Sea", a study on dissolved potentially toxic element (PTE) levels was carried out to assess the impact of treated urban wastewaters on the quality of the bathing waters in the Adriatic Sea during the 2019 and 2020 summer period. In the present study, three areas along the Italian–Croatian coastline (Gulf of Trieste, Zadar, and Split) were identified for the monitoring of five depuration plant (DP) outflows. Water samples were collected after the treatment inside the DPs, and coastal seawater was sampled in the proximity of the discharging pipelines. Dissolved Hg, Cd, and As levels were determined with an atomic fluorescence spectrometer. Results did not show statistically significant differences between treated wastewater and seawater samples (Hg 10 ± 6 and 10 ± 4, Cd 14 ± 6 and 21 ± 8, As 610 ± 176 and 687 ± 140 ng L−1, respectively), while the geographical area and the seasonality affected the PTE concentration. Furthermore, the levels detected were lower than the European and national limits, indicating a good environmental status of the northern Adriatic Sea waters. The determination of further parameters (nutrients, microbiological indicators) must be investigated to identify possible synergistic effects. However, our results demonstrate the efficiency of DPs investigated, underlining the importance of the wastewater treatment for the protection of the Adriatic Sea. [ABSTRACT FROM AUTHOR]

In coastal seas, a variety of environmental variables characterise the average annual pattern of the physico-chemical environment and influence the temporal and spatial variations of phytoplankton communities. The aim of this study was to track the annual and interannual variability of phytoplankton biomass in different size classes in the Gulf of Trieste (Adriatic Sea) using phytoplankton pigments. The seasonal pattern of phytoplankton size classes showed a co-dominance of the nano and micro fractions during the spring peak and a predominance of the latter during the autumn peak. The highest picoplankton values occurred during the periods with the lowest total phytoplankton biomass, with chlorophytes dominating during the colder months and cyanobacteria during the summer. The highest number of significant correlations was found between phytoplankton taxa and size classes and temperature, nitrate and nitrite. The most obvious trend observed over the time series was an increase in picoplankton in all water layers, with the most significant trend in the bottom layer. Nano- and microplankton showed greater variation in biomass, with a decrease in nanoplankton biomass in 2011 and 2012 and negative trend in microplankton biomass in the bottom layer. These results suggest that changes in trophic relationships in the pelagic food web may also have implications for biogeochemical processes in the coastal sea. [ABSTRACT FROM AUTHOR]

The present research aimed at evaluating the importance of endolithic holes for the spawning of blennies and at studying the selection and utilization of holes by blennies in the Gulf of Trieste. The study was conducted using the all-occurrence sampling method, a non-destructive visual census method, aided by SCUBA. Resident, egg-guarding males of Lipophrys dalmatinus, Lipophrys canevae, Aidablennius sphynx, Parablennius incognitus, Parablennius zvonimiri and Parablennius rouxi were caught. Species-specific differences in the utilization of holes were found for species that nest in endolithic holes. Smaller species (e.g. Lipophrys dalmatinus and Lipophrys canevae) choose holes that are little larger than their heads and approximately as long as their body, which prevent small males from being dislodged by bigger ones. Bigger species that are probably less exposed to interspecific competition for holes, choose mostly holes with an entrance diameter twice as big as their head diameter and much longer than their body. Species living in shallow waters (e.g. Aidablennius sphynx) prefer hole positions exposed to daylight, while species living in deeper waters were mostly found in the shade of boulders and rocks. [ABSTRACT FROM AUTHOR]

A case study was carried out in 2000 in the shallow coastal area of the Northern Adriatic Sea (Gulf of Trieste) where untreated domestic sewage and industrial wastes are discharged at rate of 5500 m3·day−1. The sewage plume above the outfall was followed using faecal coliforms (FC) and overturning length scale (lT). The latter was rejected as a marker as the discharge conditions prohibit following the turbulence of sewage water. Intermittent sewage discharge is reflected in the minimal effect of eutrophication. Increase of phytoplankton biomass is thus only minor compared with the unpolluted area regardless of elevated concentrations of sewage-derived nutrients (confirmed by correlation coefficients between FC and NH4+, TP, PO43−: 0.78, 0.71 and 0.67, respectively). Deteriorated trophic status, determined by the TRIX index, was observed only in the surface layer (average TRIX: 5.67). High FC content well above the regulation limit (up to 2.6 × 105 FC·100 ml−1) represents, therefore, the major negative impact of the improperly treated waste for the risk to human health. [ABSTRACT FROM AUTHOR]

Abstract: The variability of dissolved organic carbon (DOC) over days to a multi-year time span has been investigated in the Gulf of Trieste (northern Adriatic Sea) over a period of 5years (January 1999 to December 2003). Samples were collected in a grid of 9 to 12 stations on monthly frequency and in one station on weekly (2003) and daily (1-month) frequency. DOC samples were analyzed by the HTCO method. DOC concentration varied over the five years in the range of 50 to 194μM with annual median values ranging from 88 to 98μM. Over the years 1999–2002, DOC showed a clear annual periodicity with winter minima and late summer maxima, higher in 1999 and 2000. During 2003 no seasonality was detected. The absence of DOC seasonality and the lower DOC concentrations during 2003 are most likely related to the drought that characterized the whole year. Accumulation was calculated as the difference between averaged winter minima (59±7μM) and the monthly averaged integrated value. DOC that had accumulated from spring to summer totally disappeared from the water column in winter when DOC concentrations reached the background value. The Gulf of Trieste, as with the rest of the Northern Adriatic each year, seems to be able to bring back DOC concentrations at low levels despite the significant external (mainly Isonzo River inputs) and internal organic matter loads. DOC concentration exhibited quite wide fluctuations weekly and daily, suggesting there might be DOC of different turnover time through production, consumption, migration and accumulation. [Copyright &y& Elsevier]

A preliminary study was carried out on a picocyanobacterial mixed culture harvested from the Gulf of Trieste (Northern Adriatic) and identified as Synechococcus spp. both by transmission electron microscopy observations, biliprotein composition and molecular analyses. Absorption and fluorescence spectra revealed phycourobilin and phycoerythrobilin chromophores, suggesting the presence of both CU- and C-phycoerythrin, besides phycocyanobilin chromophores typical for phycocyanins and allophycocyanins. Both biliprotein analyses and molecular identification indicated the presence of at least two Synechococcus subgroups presumably differing either in phycoerythrin type or in physiological traits. Among the exoenzymatic activities acting on different substrates, only aminopeptidase showed high hydrolysis rates and the uptake of organic molecules was positive for leucine but not for thymidine. The protein carbon mobilized was high compared with the leucine incorporation rates, resulting in low percentages of newly mobilized carbon utilized by cultures. The organic carbon incorporated as leucine was compared with the photosynthetically produced one, and the balance between the phototrophic- and heterotrophic-like processes was c. 3 : 1. Our findings suggest that the Synechococcus heterotrophy plays an important role in cell's metabolism, and that the photoheterotrophic behavior, together with their chromatic adaptation capability, might represent the key for the absolute dominance of this genus in the Adriatic Sea. [ABSTRACT FROM AUTHOR]

Field measurements of atmospheric mercury and related species were carried out during an intensive cruise campaign performed over the Adriatic sea from October 26th to November 12th, 2004 on board the R/V Urania. Hg0 ranged between 0.8 and 3.3 ng/m3 with an average of 1.6 ± 0.4 ng/m3 over the entire period. Hg(II) concentrations ranged from 0.1 to 62.8 pg/m3 with an average of 6.7 ± 11.7 pg/m3 whereas Hg-p levels were in a range of 0.04 and 51 pg/m3 with an average of 4.5 ± 8 pg/m3. Higher Hg0 and Hg-p concentrations were observed in the Gulf of Venice and Gulf of Trieste due primarily to air masses transported from the mainland reflecting the contribution from anthropogenic sources. In contrast, higher Hg(II) concentrations observed during the first period of the cruise campaign were likely due to the occurrence of photo-oxidants production which are the main players of the gas phase oxidation of $${\rm H}{\rm g}^{0}_{({\rm g})}$$ to Hg(II)(g). These findings have been confirmed by the backward trajectories analysis of air masses crossing the studied area during selected days. [ABSTRACT FROM AUTHOR]

The established geographical name Bay of Piran refers to the largest bay in the Gulf of Trieste at the extreme north end of the Adriatic Sea. After the collapse of Yugoslavia and the emergence of independent countries demarcated along the borders of the former Yugoslav republics, the previously undemarcated body of water between Slovenia and Croatia became the focus of a border dispute between the two countries. One of the basic principles of proper treatment of geographical names is not to change established and widely used names. The name 'Bay of Piran' (Sln. Piranski zaliv, Cro. Piranski zaljev) is derived from the Italian name Vallone di Pirano 'Bay of Piran', which replaced the Italian name Valle di Sicciole 'Bay of Sečovlje' (as well as Ital. Valle di Siciole, Sln. Sečoveljski zaliv) a century and half ago. This in turn was established towards the end of the 18th century, replacing the Italian name Largon 'Broad' or Golfo Largone 'Broad Bay'. Since 2000 there have been Croatian attempts to establish the completely new name 'Bay of Savudrija' (Cro. Savudrijska vala, Sln. Savudrijski zaliv). [ABSTRACT FROM AUTHOR]

To reconstruct a history of polycyclic aromatic hydrocarbon (PAH) pollution in the Gulf of Trieste, one of the largest urbanized areas in the Adriatic Sea, we analyzed three long sediment cores collected between 1996 and 1997. Concentrations of total PAHs, the sum of 16 PAH compounds and six of their methylated analogues, in all three cores show a decrease from 600–800 ng g−1, at the surface, to levels below 250 ng g−1 in deepest layers (down to 3 m). The same trend was shown with separate representative pyrogenic PAHs (pyrene, benzofluoranthene and phenanthrene). Using Hg as a recent geochronological tracer, we observe an increasing input of PAHs since the beginning of the 20th Century and, especially, after the Second World War coinciding with increasing industrialization and urbanization of the region. This correlation is supported by PAH ratios that are indication of combustion processes and represent a marker for anthropogenic inputs. No correlation exists between PAHs and black carbon within the core profiles, indicating two different fractions of the ‘black carbon continuum’. [ABSTRACT FROM AUTHOR]

Three burrow systems produced by Jaxea nocturna and one cluster of burrows produced by Upogebia pusilla where investigated in the Bay of Panzano, Northern Adriatic Sea, to determine preferred orientations. The distributions of dip directions differ between both producers. Steep shafts into the consolidated mud followed by large, shallowly inclined tunnels oriented in a manner similar to a spiral are characteristic for Jaxea nocturna burrows. In contrast, the Y-shaped burrows of Upogebia pusilla have entrance shafts that are less steep which are connected by a near-horizontal section, where a blind ending tunnel branches. Orientations of the dominating, shallowly inclined burrow parts are not randomly distributed in either Jaxea or in Upogebia burrows. Three preferred axial orientations with almost equal proportions in each direction are characteristic for the Jaxea burrow from the centre of the bay. This system transforms to a squared structure near the coast, where one direction parallels the shoreline and the other is oriented at right angles to the coast. The latter orientation demonstrates significant constancy in all investigated burrows. Upogebia burrow clusters coincide with the three preferred orientations of the Jaxea burrow from the bay centre, but the proportions of the directions are unequal. Burrow segments connecting the steep entrance shafts in Upogebia are oriented almost parallel to the shoreline, whereas at right angles to the coast the flat blind-ending tunnels incline towards the open sea. The study shows a strong coincidence between empirical and theoretical distributions of the dominating orientations in both species. [ABSTRACT FROM AUTHOR]

Abstract: According to bioassay studies and high dissolved nutrient N/P ratios in the seawater column, phosphorus (P) is thought to control marine productivity in the northern Adriatic Sea. P in near-shore marine sediments of the Gulf of Trieste, the northernmost part of the Adriatic Sea, was investigated using pore water P distributions, and benthic P flux studies under oxic and anoxic conditions. The data show that P regeneration is up to three-fold more extensive in sediments overlain by oxygen-depleted waters and proceeds in parallel with Fe and Mn enhanced benthic fluxes. It appears from the incubation experiments that degradation of sedimentary organic matter is the main contribution to the flux of P at the sediment–water interface, while the release of phosphate adsorbed on the iron oxide surface is of minor importance. It appears that about 50% of P in the Gulf of Trieste is retained within in the sediments, probably bonded to clay minerals and carbonate grains or precipitated as fluoroapatite. In these sediments total P (Ptot) is preserved preferentially over organic C (Corg). P regenerated from surficial sediments contributes about 1/3 of the P that is assimilated by benthic microalgae. The phytoplankton P requirement should be entirely supplied from fresh-water sources. These results suggest that oxygen depletion in coastal areas caused by eutrophication enhances P regeneration from sediments, providing the additional P necessary for increased biological productivity. The development of anoxic bottom waters in coastal areas enhances the recycling of P, exacerbating the nutrient requirement in the area. A geochemical record of P burial in a longer sedimentary sequence revealed an increasing trend of Ptot and organic P (Porg) contents occurring approximately 50 years BP (after 1950), probably due to increasing use of inorganic fertilizers and detergents in the area. [Copyright &y& Elsevier]

Species composition, richness and abundance of the fish assemblage were studied over six different inshore macrohabitats in the southern part of the Gulf of Trieste (Northern Adriatic Sea) using the visual counts technique. Fifteen environmental variables were taken into consideration in order to determine microhabitat preferences of fish species, using canonical correspondence analysis and electivity indices. The results suggest that the structure of the fish assemblage in shallow habitats is affected by a large number of interplaying factors. Depth, type of bottom and vegetation cover– incorporating both abiotic and biotic variables– are some of the factors responsible for coastal fish distribution. Microhabitat preferences for 29 fish species are presented in the depth range from 0.5 to 3 m. [ABSTRACT FROM AUTHOR]

In the shallow and landlocked northeast Adriatic Sea, environmental factors have changed in recent decades. Their influence on seasonal and inter-annual variability of phytoplankton has been documented in the recent literature. Here, we decipher the long-term variability of phytoplankton phenology at a Long-Term Ecological Research site (Gulf of Trieste, Slovenia). Structural changes in the phytoplankton community (period 2005–2017) were analysed using a multivariate protocol based on Bayesian clustering. The protocol was modified from the literature to fit the needs of the study, using correspondence analysis and k-means clustering. A novel index for ordination and selection of taxa based on frequency and evenness was developed. The Total Inertia analysis showed that this index better preserved the available information. Typical seasonal assemblages were highlighted by applying the Indicative Value index in conjunction with likelihood ratio values. We obtained a rough picture of the seasonal separation of the diatom-dominated community from the mixed community and a refined picture of the phenology of the assemblages and bloom events. The spring diatom peak proved to be inconstant and short-lived, while the autumn bloom was generally long and diverse. As expected for nearshore environments, the average life span of the assemblages was found to be short-periodic (2–4 months). The second part of the year and the last part of the series were more prone to changes in terms of typical assemblages. [ABSTRACT FROM AUTHOR]

Seasonal and inter-annual variability of environmental characteristics and of plankton were analysed based on monthly surveys of the physical structure of the water column, nutrients, phytoplankton, and zooplankton biomass and abundance in the Gulf of Trieste (1989–1995). Seasonal plankton dynamics were related to Soĉa River run-off, the main freshwater source, and peaks of autotrophic biomass were associated with extended periods of high freshwater inflow. Our results indicate that the freshwater discharge during spring was more important for annual phytobiomass than total yearly input. In 1993, which was characterized by a relatively high total annual freshwater input but by a dry spring, the lowest average chlorophyll biomass (0.85 μg l−1) and cumulative monthly mesozooplanktonic biomass (123 mg AFDW m−3) were observed over the entire period. Annual peaks of phytoplankton biomass were mainly due to increases in diatom abundance, while small-sized cells (microflagellates, coccolithophores) dominated during periods of low Chl a concentrations. Consumer community patterns followed autotrophic biomass evolution with high abundance of herbivores and mixed feeders in spring, and fine-filter feeders and planktonic protists during summer. A large inter-annual variability emphasizes the importance of long-term monitoring in areas like the Gulf of Trieste for distinguishing anthropogenic trends from natural variations of plankton. [ABSTRACT FROM PUBLISHER]