Panel 1
Patrizia Borrello, Emanuela Spada
The "chlorophyll" parameter is the only direct indicator of phytoplankton biomass available and has taken on the role of a metric for classifying ecological status according to the Biological Quality Element (BQE) – Phytoplankton in coastal waters (Ministerial Decree 260/2010). Chlorophyll is particularly sensitive to changes in trophic levels determined by nutrient (N and P) inputs from catchment basins flowing into the coastal area.
In 2020, high status was recorded in 71.4% of cases, good status in 12.3%, and sufficient status in 16.2%. A general improvement in status was observed in Campania and Marche, while Emilia-Romagna and Sardinia saw a worsening. Marche, Liguria, and Abruzzo maintained all stations at high status.
Chlorophyll a is a primary indicator of phytoplankton biomass. As such, it is sensitive to changes in trophic levels determined by nutrient (N and P) loads from catchment basins affecting the examined coastal area. The chlorophyll parameter is commonly measured fluorometrically, using a multiparameter probe. This allows the measurement results to be graphically presented as vertical profiles along the water column.
The availability of nutrients, in their dissolved mineral form, elicits a response from the coastal ecosystem in terms of increased primary production. The key role of the chlorophyll a parameter is to document this increase.
In this sense, chlorophyll a ceases to be merely the photosynthetic pigment contained in the chloroplasts—organelles present in every phytoplankton cell—and becomes the most important of the trophic indicators. Although the functional relationships between chlorophyll and autotrophic phytoplankton biomass (in terms of cell count per liter, weight, etc.) are complex, this parameter is nonetheless the only directly measurable and widely monitored indicator of phytoplankton biomass in coastal water quality control programs.
In accordance with Legislative Decree 152/2006 and subsequent amendments, the classification used to represent the indicator is based on the water body's typology. Specifically:
- For macrotype 1 (coastal sites heavily influenced by freshwater inflows), the “chlorophyll a” value is calculated using the geometric mean.
- For macrotypes 2 and 3 (moderately influenced or not influenced by freshwater inflows), the 90th percentile of the normalized data distribution is used.
The high/good class threshold for macrotypes 1 and 2 is 2.4 mg/m³, while for macrotype 3 it is 1.1 mg/m³.
The good/sufficient class thresholds are 3.5, 3.6, and 1.8 mg/m³ for macrotypes 1, 2, and 3, respectively.
To assess the ecological status of coastal waters based on the BQE Phytoplankton, in accordance with Legislative Decree 152/2006 and subsequent amendments. This allows for the setting of quality objectives to be maintained and/or achieved. Spatial analysis of the indicator enables the establishment of relationships between nutrient loads in coastal systems and their response in terms of phytoplankton biomass production.
Time series analysis of chlorophyll a data also enables monitoring of the effectiveness of strategies and actions taken for nutrient control and removal.
Legislative Decree 152/2006 and subsequent amendments. In accordance with Legislative Decree 152/2006, which mandates biological monitoring per Directive 2000/60/EC and Ministerial Decree 260/2010, which defines the ecological status classification criteria, every surface water body, including coastal waters, must achieve and maintain “good” environmental quality status by 2015.
Panel 2
Devlin, M., Best, M., Coates, D., Bresnan, E., O'Boyle, S., Park, R., Silke, J., Cusack, C. & Skeats, J. (2007). Establishing boundary classes for the classification of UK marine waters using phytoplankton communities. Marine Pollution Bulletin 55: 91-103. Giovanardi, F., Finoia, M.G., Russo, S., Amori, M. and B. Di Lorenzo, 2006. Coastal waters monitoring data: frequency distributions of the principal water quality variables. J. Limnol., 65(2): 65-82 Giovanardi, F. and E. Tromellini, 1992. Statistical Assessment of Trophic Conditions. Application of the OECD Methodology to the Marine Environment. Proc. Int. Conf. Marine Coastal Eutrophication. Sci. Total Environ. Suppl. 1992: p. 211-233. OECD – Vollenweider, R.A. and J.J. Kerekes Eds, 1982. Eutrophication of Waters, Monitoring, Assessment and Control-O.E.C.D.-Paris. WFD Intercalibration Phase 2: Milestone 5 report, 2011
Data quality assessment
Coastal ARPA
The basic information is accessible through the SINTAI system - http://www.sintai.sinanet.apat.it/ used by coastal ARPA to transmit data using shared information standards at national level.
Anno 2018: Coastal regions 12/15 Anno 2019: Coastal regions 11/15 Anno 2020: Coastal regions 14/15
2018-2019-2020
Indicator assessment
Within the framework of the works for the Intercalibration of the methods and classification criteria related to the BQE (Biological Quality Element) phytoplankton, as provided by Directive 2000/60 WFD, the Member States belonging to the Mediterranean Eco-Region have mainly adopted two types of metrics based on chlorophyll a: the value of the 90th percentile for distributions of chlorophyll a normalized through logarithmic transformation and referring to a period of at least 5 years, and the value of the geometric mean, calculated over a period of at least one year. For further details, reference is made to the technical annex of the Classification Decree (Ministerial Decree Environment 260/2010).
In accordance with what is provided in Legislative Decree 152/2006 and subsequent amendments and additions, the classification to represent the indicator is carried out based on the type of water body. In particular, for macrotype 1, corresponding to coastal sites strongly influenced by inputs of continental freshwater, the value of “chlorophyll a” is calculated using the geometric mean. For the types included in macrotopes 2 and 3, corresponding respectively to coastal sites moderately influenced or not influenced by inputs of continental freshwater, the 90th percentile is considered for the normalized distribution of data for the calculation of the “chlorophyll a” value.
The high/good class boundary limit for macrotopes 1 and 2 is 2.4 mg/m³, while it is 1.1 mg/m³ for macrotype 3; the good/moderate class boundary limits are 3.5, 3.6, and 1.8 mg/m³ for macrotopes 1, 2, and 3 respectively.
In 2020, high status was recorded in 71.4%, good status in 12.3%, and sufficient status in 16.2% of stations (Table 1, Figure 1). Campania and Marche saw general improvements, while Emilia-Romagna and Sardinia worsened. Friuli Venezia Giulia remained stable. Liguria, which nearly doubled its stations, along with Marche and Abruzzo, had all stations in high status. Stations classified as high and good totaled about 88.5%, but the increase in stations with sufficient status prevented achievement and maintenance of “good” environmental quality status.
Trend
In 2018, 72% of coastal stations across 12 reporting regions were in high status, 20% in good, and 8% in sufficient status. In 2019, high status stations reached nearly 80%, good status dropped to 11.3%, and sufficient status decreased to 4%, favoring the high status category. In 2020, there was a slight decline in high status (71.4%), a slight increase in good status (12.3%), and a notable increase in sufficient status (16.2%) compared to previous years.
Data
Table 1: Number of stations by quality classes - Organic Quality EQB Fitoplancton Chlorophylla a
ISPRA processing on data from coastal ARPA
/data not received
Figure 1: Classification EQB Fitoplankton - Chlorophyll a (2020)
ISPRA processing on ARPA data
The processed data (Table 1) refer only to stations from regions that formally and completely submitted ecological status classification information for the BQE Phytoplankton in Coastal Waters to SINTAI. Each region reports its stations classified on a “high – good – sufficient – poor – bad” scale based on the “chlorophyll a” index value, considering the macrotipo of the water body each station belongs to.
From 2018 to 2020, despite a decrease in the number of stations, there was an increase in stations rated sufficient (from 23 to 42) (Table 1 and Figure 1). The sufficient status rating mainly pertains to Sicily, Sardinia, and the northern Adriatic coast (Emilia-Romagna), which belongs to macrotipo I (High Stability). For the latter, the direct role of the Po River and other catchments flowing into the northern Adriatic in maintaining high trophic levels is confirmed.
As for Sicily and Sardinia, the cause is likely nutrient inputs from smaller rivers, which can locally elevate trophic levels.
For the Tyrrhenian coastal regions, from 2018 to 2020, there was a clear improvement in Lazio and Campania. Lastly, the significant percentage of stations in high status is consistent with the general oligotrophic nature of Tyrrhenian coastal waters (Table 1).