Assessment of the eutrophication status at Mediterranean sub-basin scale, within the European Marine Strategy Framework Directive.

The aim of this work is to define harmonized reference conditions and assessment thresholds for selected criteria elements of the Marine Strategy Framework Directive (MSFD) Descriptor 5 (Eutrophication) in the Eastern Mediterranean Sea and to test if a tool for integrated assessment of the status of marine systems can be used as a common methodological approach. In this frame, we tested two statistical approaches in order to set threshold values for four criteria of Descriptor 5: nutrients, chlorophyll a, transparency and dissolved oxygen in the bottom waters. It is noteworthy that this work revealed the need to apply common procedures in data treatment and assessment evaluation. This is the first attempt to set common methods for the assessment of eutrophication in the Eastern Mediterranean, which is essential in marine environments, especially those shared by several countries. To this end, we have applied common criteria and metrics and established thresholds "Good" and "Moderate" for nutrients, chlorophyll a, transparency and dissolved oxygen in the bottom waters for the different Water Types of the Adriatic and Aegean Seas (I, II, IIIW, IIIE), based on datasets provided by Italy, Slovenia, Croatia and Greece. The selected criteria elements were common for all countries, providing a unified approach to GES assessment of two case study areas: the Adriatic Sea and the Saronikos Gulf. Dissolved Inorganic Nitrogen (DIN) threshold values of 15.6, 6.85, 1.61 and 2.11 µmol L-1 were set for the Water Types I, II, IIIW and IIIE, respectively. We also tested if an aggregation tool for GES assessment, such as Nested Environmental status Assessment Tool (NEAT), could be used as a common methodological approach. The comparison of NEAT with TRIX showed good comparability. In this end, NEAT can be used as a useful and much needed assessment tool for assessing eutrophication status of the marine.

Phytoplankton community and physical-chemical data measured in the Gulf of Trieste (northern Adriatic Sea) over the period March 2006-February 2007.

Biological, hydrological and chemical data were acquired at monthly intervals from March 2006 to February 2007, at the Long-Term Ecological Research site C1 in the Gulf of Trieste, in the northernmost part of the Adriatic Sea. The biological dataset comprises total chl a and phaeopigment concentrations, and the distinction of the total phytoplankton biomass into three photoautotrophic community fractions, i.e. cyanobacteria, nano- and microphytoplankton, collected at discrete depths. Hydrological data encompass the thermohaline properties of the water column (temperature and salinity profiles from CTD casts). Chemical data consist of silicate and phosphate concentrations obtained from discrete seawater samples collected with Niskin bottles at four depths (0.5-5-10-15 m). Data presented here are related to the paper "Structural and functional response of phytoplankton to reduced river inputs and anomalous physical-chemical conditions in the Gulf of Trieste (northern Adriatic Sea) by Cibic et al. (2018) [1].

Plankton dynamics across the freshwater, transitional and marine research sites of the LTER-Italy Network. Patterns, fluctuations, drivers.

A first synoptic and trans-domain overview of plankton dynamics was conducted across the aquatic sites belonging to the Italian Long-Term Ecological Research Network (LTER-Italy). Based on published studies, checked and complemented with unpublished information, we investigated phytoplankton and zooplankton annual dynamics and long-term changes across domains: from the large subalpine lakes to mountain lakes and artificial lakes, from lagoons to marine coastal ecosystems. This study permitted identifying common and unique environmental drivers and ecological functional processes controlling seasonal and long-term temporal course. The most relevant patterns of plankton seasonal succession were revealed, showing that the driving factors were nutrient availability, stratification regime, and freshwater inflow. Phytoplankton and mesozooplankton displayed a wide interannual variability at most sites. Unidirectional or linear long-term trends were rarely detected but all sites were impacted across the years by at least one, but in many case several major stressor(s): nutrient inputs, meteo-climatic variability at the local and regional scale, and direct human activities at specific sites. Different climatic and anthropic forcings frequently co-occurred, whereby the responses of plankton communities were the result of this environmental complexity. Overall, the LTER investigations are providing an unparalleled framework of knowledge to evaluate changes in the aquatic pelagic systems and management options.