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

Abstract

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

Linking lifestyle and foraging strategies of marine bacteria: selfish behaviour of particle‐attached bacteria in the northern Adriatic Sea

“…The set of FLA‐PS used in the present study includes some of the most abundant or readily hydrolysed polysaccharides in the ocean (Arnosti, 2011; Becker et al ., 2020), which are likely derived from primary producers (Mühlenbruch et al ., 2018; Bäumgen et al ., 2021). The study area is heavily influenced by riverine inputs, representing the major source of inorganic nutrients (Cozzi et al ., 2020), driving seasonal and interannual changes in both autochthonous and allochthonous OM standing stocks and, consequently, in microbial OM utilization patterns (Celussi and Del Negro, 2012; Manna et al ., 2021).…”

Bacterial Indicators Are Ubiquitous Members of Pelagic Microbiome in Anthropogenically Impacted Coastal Ecosystem

“…River discharges, mainly regulated by precipitation with peaks in early spring and autumn, importantly influence nutrient dynamics in this area ( Klun et al, 2019 ). The greatest discharge source is the Soča (Isonzo) River, whereas minor rivers along the southern Slovenian coast, such as Rižana, have an impact on turbidity, freshwater, and nutrient content at a smaller spatial scale ( Faganeli and Turk, 1989 ; Mandac and Faganeli, 2015 ; Cozzi et al, 2020 ; Figure 1 ). In recent years, a decrease in river loads of nutrients was observed, indicating that other allochthonous sources, such as wastewater loads, might become more important for this system ( Cozzi et al, 2012 ).…”

Global-scale parameters for ecological models

“…In the Aegean Sea, this parameter had a higher weight in 2020 and 2019 than in 2018 and 2017, and its distribution resembled the one of the Adriatic Sea in 2020 and 2019. The parameter contribution rankings in 2018 and 2017 in the Aegean Sea changed with respect to 2020 and 2019, in correspondence of the anticyclonic Bimodal Oscillating System regime effect 86 , 99 – 101 .…”

“…These regions also have generally similar parameter trends and are geographically connected. Habitat dissimilarity between the Aegean and Adriatic seas in 2018 and 2017 corresponds to a known effect of an anticyclonic Bimodal Oscillating System regime that prevented eastern waters from entering the Adriatic in those years 86,[99][100][101] . General habitat similarity between the North Sea and the Baltic Sea has also been highlighted by other studies, unless regime shifts occur [102][103][104] .…”