Trends in chlorophyll-a concentrations in European seas (1980-2019)

• Oceanographic database, International Council for the Exploration of the Sea (ICES)
• Chemistry data - Data & products on marine water quality, European Marine Observation and Data Network (EMODnet)

• Baltic Sea
• Bay of Biscay
• Black Sea
• Celtic Sea
• Greater North Sea
• Iberian Coast
• Macaronesia
• Mediterranean Sea
• North-East Atlantic Ocean

• Temporal trends were estimated in locations with data for at least 5 years in the period 1980-2019 and updated in the last 5-year period (2015-2019), using the non-parametric Mann-Kendall test. A p-value of <0.05 was considered to indicate a statistically significant trend.
• Results reflect data availability, which may vary significantly across regions and over time.

Temporal coverage
1980-2019 (the temporal range specified is the maximum range of dates for raw observations but this range varies upon the availability of observations at each location).

Methodology
Based on datasets produced for the CSI032_MAR006_Chlorophyll in transitional, coastal and marine waters_2021 Indicator, the percentage of the number of locations with significant decreasing trend (green), no trend (grey) and increasing trend (orange) were calculated by marine region and plotted in a bar-type chart.