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Long-term baseline data that allow tracking how predator–prey interactions have responded to intensifying human impacts are often lacking. Here, we assess temporal changes in benthic community composition and interactions between drilling predatory gastropods and their molluscan prey using the Holocene fossil record of the shallow northern Adriatic Sea, which is characterized by a long history of human transformation. Molluscan assemblages differ between the Isonzo and Po prodelta, but both show consistent temporal trends in the abundance of dominant species. Samples of mollusc prey collected at high stratigraphic resolution indicate that drilling frequencies have drastically declined in the Po prodelta since the mid-twentieth century, while a weaker trend in the more condensed sediments of the Isonzo prodelta is not statistically significant. The decrease in drilling predation intensity and the community turnover are linked to the loss of predatory gastropods and the increased relative abundance of less-preferred prey during the most recent decades. Our results align with data showing the substantial depletion of marine resources at higher trophic levels in the region and indicate that the strong simplification of the food web initiated in the late nineteenth century accelerated further since the mid-twentieth century. [ABSTRACT FROM AUTHOR]

The effects of the climate crisis are affecting ecosystems at different scales and magnitudes. This paper focuses on a massive Mediterranean mussel die-off observed along the middle Italian Adriatic coast in the summer of 2022. We considered the possible environmental causes of this phenomenon and carried out a climatic analysis of the last decade. We performed field surveys in different locations along a 16 km coastal stretch from Martinsicuro (TE) in the south, to Grottammare (AP) in the north. The study area includes two marine Sites of Community Importance under the European Natura 2000 network. The die-off of the mussels was observed in practically all the natural mussel beds colonizing the study area. As sessile filter-feeding organisms inhabiting the intertidal zone, mussels are highly exposed to variations in environmental conditions such as temperature and nutrient load. We discuss the possible causes of this die-off, proposing that high temperature and the scarce availability of food acted simultaneously as stress factors, generating local unsustainable living conditions for this species. [ABSTRACT FROM AUTHOR]

This paper described the implementation of a forecasting system of the coupled physical and biogeochemical state of the northern Adriatic Sea and discussed the preliminary results. The forecasting system is composed of two components: the NEMO general circulation model and the BFM biogeochemical model. The BFM component includes an explicit benthic pelagic coupling providing fluxes at the sediment–water interface and the dynamic of the major benthic state variables. The system is forced by atmospheric forcing from a limited-area model and by available land-based (river runoff and nutrient load) data. The preliminary results were validated against available remote and in situ observations. The validation effort indicated a good performance of the system in defining the basin scale characteristics, while locally the forecasting model performance seemed mostly impaired by the uncertainties in the definition of the land-based forcing. [ABSTRACT FROM AUTHOR]

This study sheds light on the influence of dissolved oxygen (DO) and temperature on fine-scale zooplankton vertical distribution in a seasonally stratified, enclosed marine lake on the Croatian island of Mljet. Unusually high precipitation during the spring and summer of 2014 caused extended hypoxia above the bottom in the autumn. Nauplii, copepodites, Oithona nana and appendicularians strictly avoided the layers of reduced DO. Copepods Oithona similis, Mesaiokeras hurei, oncaeids, and polychaeta trochophore comprised a community adapted to the hypoxic bottom layer (10%-14% dissolved oxygen). Oncaeids were the most abundant and were presented by two small species: Oncaea zernovi and the more numerous Monothula subtilis. Polychaeta larvae were extraordinary numerous, too. Proliferation of ocaeids and polychaeta larvae in hypoxic zone could be related to their ability to feed on detrital matter and associated microbial community. Contrary, low abundance of other copepod developmental stages were found in the whole water column suggesting that the high load of organic material and hypoxic events inhabited their reproduction. Our study has documented the dramatic impact of local environmental changes on the planktonic community, providing additional evidence that low oxygen has an effect on the distribution and abundance of zooplankton. [ABSTRACT FROM AUTHOR]

In sediment cores spanning ~500 years of history in the Gulf of Trieste, down-core changes in molluscan community structure are characterized by marked shifts in species and functional composition. Between the 16th and 19th century, a strong heavy metal contamination of the sediments, most notably by Hg, together with the effects of natural climatic oscillations (increased sedimentation and organic enrichment) drive community changes. Since the early 20th century up to 2013, the combined impacts of cultural eutrophication, frequent hypoxic events and intensifying bottom trawling replace heavy metal contamination and climatic factors as the main drivers. The pollution-tolerant and opportunistic bivalve Corbula gibba and the scavenging gastropod Nassarius pygmaeus significantly increase in abundance during the 20th century, while species more sensitive to disturbances and hypoxia such as Turritella communis and Kurtiella bidentata become rare or absent. An infaunal life habit and scavenging emerge as the dominant life strategies during the late 20th century. Down-core shifts in the proportional abundances of molluscan species and functional groups represent a sensitive proxy for past ecological changes and reveal a century-long anthropogenic impact as the main driver behind these processes in the northern Adriatic Sea, offering also a unique perspective for other shallow marine ecosystems worldwide. [ABSTRACT FROM AUTHOR]

Influenced by one of the largest Mediterranean rivers, Po, the northern Adriatic (NA) production is highly variable seasonally and interannually. The changes are especially pronounced between winters and seemingly reflect on total Adriatic bioproduction of certain species (anchovy).We analysed the long-term changes in the phytoplankton production in the region, as derived from monthly oceanographic cruises, in relation to concomitant geostrophic currents distribution in the area and to Po River discharge rates in days preceding the cruises. In winter and early spring the phytoplankton abundances depended on existing circulation fields, in summer and autumn they were related to Po River discharge rates 1-15 days earlier and on concomitant circulation fields, while in late spring phytoplankton abundances increased 1-3 days after high Po River discharge rates regardless of the circulation fields. During the entire year the phytoplankton abundances were dependent on forcing of the previous 1-12 months of surface fluxes and/or Po River rates. The role of wind was uncertain but that was partly due to unmatched sampling time frames between meteorological and sea data. Low evaporation rates in November reflected significantly on the next February circulation pattern and, although with somewhat lower significance, on large phytoplankton blooms in the same month.We showed that the role of wind in evaporative flux enhancements is not straightforward as evaporative fluxes are highly dependent on other factors, e.g. air-sea temperature difference. Wind-induced vertical mixing was only sporadically related to phytoplankton abundances. From 1990 to 2004 a shift towards large winter bioproduction induced by circulation changes appeared. The investigations performed represent the preliminary actions in the construction of an empirical ecological model of the NA which can be used in the sustainable economy of the region, as well as for validation of the numerical ecological model of the region, which is currently being developed. [ABSTRACT FROM AUTHOR]

Influenced by one of the largest Mediterranean rivers, Po, the northern Adriatic production is highly variable seasonally and interannually. The changes are especially pronounced between winters and seemingly reflect on total Adriatic bioproduction of certain species (anchovy). We analysed the long-term changes in the phytoplankton production at the transect in the region, as derived from monthly oceanographic cruises, in relation to concomitant geostrophic currents distribution in the area and in the Po River discharge rates in days preceding the cruises. In winter and early spring the phyto-abundances depended on existing circulation fields, in summer and autumn they were related to 1-15 days earlier Po River discharge rates and on concomitant circulation fields, while in late spring phyto-abundances increased 1-3 days after high Po River discharge rates regardless of circulation fields. During the entire year the phytoabundances were dependant on forcing of the previous 1-12 months of surface fluxes and/or Po River rates. Large February blooms are, as well as February circulation patterns, precondited by low evaporation rates in previous November. From 1990 to 2004 a shift towards large winter bioproduction induced by circulation changes appeared. Performed investigations represent the preliminary actions in building of an empirical ecological model of the northern Adriatic which can be used in the sustainable economy of the region, however also in validation of the numerical ecological model of the region, which is currently being developed. [ABSTRACT FROM AUTHOR]

The article discusses the role of hydrophobic interactions in the gel network formation by applying atomic force microscopy (AFM) to image marine gel samples taken during episodes of macroscopic gel phase formation in the northern Adriatic Sea and to follow initial stages of the gel network formation in a mesocosm phytoplankton bloom experiment. Sampling was done on board a research vessel during regular cruises along the transect Po River Delta-Rovinj, Istrian coast. It suggests that AFM is a powerful technique for characterizing marine gel network.

In the last century, large watersheds in Southern Europe have been impacted by a combination of anthropogenic and climatic pressures, which have rapidly evolved to change the ecological status of freshwater and coastal systems. A comparative analysis was performed for Ebro, Rhône, Po and Danube rivers, to investigate if they exhibited differential dynamics in hydrology and water quality that can be linked to specific human and natural forces acting at sub-continental scales. Flow regime series were analyzed from daily to multi-decadal scales, considering frequency distributions, trends (Mann–Kendall and Sen tests) and discontinuities (SRSD Method). River loads of suspended matter, nutrients and organic matter and the eutrophication potential of river nutrients were estimated to assess the impact of river loads on adjacent coastal areas. The decline of freshwater resources largely impacted the Ebro watershed on annual (−0.139 km3 yr−1) and seasonal (−0.4% yr−1) scales. In the other rivers, only spring–summer showed significant decreases of the runoff coupled to an exacerbated flow variability (0.1–0.3% yr−1), which suggested the presence of an enhanced regional climatic instability. Discontinuities in annual runoff series (every 20–30 years) indicated a similar long-term evolution of Rhône and Po rivers, differently from Ebro and Danube. Higher nutrient concentrations in the Ebro and Po (+50%) compared to Rhône and Danube and distinct stoichiometric nutrient ratios may exert specific impacts on the growth of plankton biomass in coastal areas. The overall decline of inorganic phosphorus in the Rhône and Po (since the 1980s) and the Ebro and Danube (since the 1990s) mitigated the eutrophication in coastal ecosystems inducing, however, a phase in which the role of organic phosphorus loads (Po > Danube > Rhône > Ebro) on coastal productivity could be more relevant. Overall, the study showed that the largest South European watersheds are differently impacted by anthropogenic and climatic forces and that this will influence their vulnerability to future changes of flow regime and water quality. [ABSTRACT FROM AUTHOR]