## 4 Final Considerations, and Future Directions  
The Northern Adriatic Sea has experienced significant changes in eutrophication pressure over the past decades. From the 1970s to the mid-1980s, eutrophication increased, but it reversed course in the 2000s. This shift can be attributed to the combination of factors. Firstly, there was a reduction in anthropogenic impact, mainly due to a substantial decrease in phosphorus loads. Additionally, climatic changes played a role, leading to a decline in atmospheric precipitation and, subsequently, a decrease in runoff into the Northern Adriatic Sea. During the period 2000-2009, there was a significant decrease in the Po River outflow, which caused altered circulation patterns. As a consequence, there was a more frequent inflow of high salinity and oligotrophic water from the central Adriatic, resulting in a change in salinity and nutrient budget of the entire Northern Adriatic [15; 33]. A four-decadal data set was analyzed to gain a better perspective of the driving pressures of phytoplankton in the Northern Adriatic. It was found that spring is the more critical season for the overproduction of organic matter [16; 80; 81]. Consequently, during the period 2000-2009, the intensity of phytoplankton blooms diminished, as evidenced by the decrease in chlorophyll \(a\) concentration [82]. [PERSON] et al. [83] analyzed spatio-temporal distribution data extracted from a long-term phytoplankton in situ monitoring data set conducted by monthly to quarterly sampling between the years 1978 and 2020 offshore in the Northern Adriatic Sea. The analysis revealed hydrodynamic regime shifts in the system which had altered the phytoplankton abundance, community composition, and seasonal cycle. Notably, appearance and frequency alterations of some prominent taxa (e.g., _Pseudo-nitzschia delicatsisima_ group and _Pseudo-nitzschia seriata_ group) were detected. [PERSON] et al. [84] described the changes in phytoplankton time series along the western coast of the Northern Adriatic Sea, showing a regular annual period in the composition structure of the coastal strip. The research indicates that the phytoplankton composition is influenced by various environmental factors, including physical variables and nutrient availability. The persistence of species in phytoplankton communities over the long term is normally affected by factors such as nutrient loads, climate change, and human pressures, while still maintaining a stabile structure. In the Northern Adriatic Sea, this may impact the succession of functional groups of species and overall productivity of the ecosystem. However, due to stochastic environmental and climate changes, as well as enhanced environmental pressures, the time series have lost their regularity, causing changes in the succession and species composition of phytoplankton communities. [PERSON] et al. [85] conducted a comparison between one coastal strip station and one offshore station along a transect along the western coast. The Western Adriatic Current (WAC, [14; 20; 86]), combined with river inflows, exerts a direct impact on coastal stations, resulting in heightened variability, as illustrated in the comparison with an offshore station. This disparity is particularly evident during winter and autumn, whereas similarity increases during the summer months when river waters spread outwards into the open sea. Owing to its oligotrophic nature, the offshore phytoplankton community demonstrated a greater level of biodiversity in contrast to observations along the coastline, where more prominent algal blooms tend to take place. Over the past four decades, a gradual depletion of N and P has been observed along the coastal strip of the Northern Adriatic [23; 87], compared to the previous period (1969-1992) [80]. This trend is expected to continue in the coming decades [19; 79], due to lower flows from rivers with minor anthropic impact, resulting in reduced N and P loads. The study conducted by [PERSON] et al.