Figure

Average concentrations and trends of surface chlorophyll-a in transitional, coastal and marine waters surrounding Europe

Figure Created 24 Jan 2024 Last modified 21 Mar 2024

2 min read

Topics: Water and marine environment

Average summer surface chlorophyll-a concentration (left) and trends (right), in locations recently updated (last update>2016) with at least 5 years of observations, in the period between 1980 and 2021. Green circles indicate stations with significant (p<0.05) decreasing trends (i.e., improving); orange circles show stations with significant (p<0.05) increasing trends (i.e., deteriorating); and grey circles show stations with no significant trends. Colour keys of symbols and values are included in the legend.

https://www.eea.europa.eu/data-and-maps/figures/average-concentrations-left-and-trends-1/fig1-259751-mar006-v3.eps/image_large

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Metadata

Units:: Chl-a status in µg/l; trends have no units
Rights:: Copyrights of the datasets: please take a look at https://www.ices.dk/data/guidelines-and-policy/Pages/ICES-data-policy.aspx
and https://www.emodnet-chemistry.eu/data/acknowledgement
Copyrights of the figure: EEA standard re-use policy: unless otherwise indicated, re-use of content on the
EEA website for commercial or non-commercial purposes is permitted free of charge, provided that the source is acknowledged
(https://www.eea.europa.eu/legal/copyright). Copyright holder: European Environment Agency (EEA).
Owners:: European Environment Agency (EEA)
Processors:: NIVA Denmark
Figure type:: Map

Additional information

• Average concentrations of chlorophyll-a (µg/l) and trends were calculated using data from observations in summer from the upper 10m of the water column, in locations with annual data for the last 5-year period (2016-2021).
• Growing season months considered are June-September for stations in the Baltic Sea north of 59 N and May–September for all other stations.
• Data were aggregated into squares with sides of 1.375km for coastal stations within 20km from the coastline and 5.5km for open water stations (more than 20km away from the coastline). A masking of 5km inwards from the coast was also applied.
• Temporal trends were estimated in locations with data for at least 5 years in the period 1980-2021 and updated in the last 5-year period (2017-2021), using the non-parametric Mann-Kendall test. A p-value <0.05 was considered to indicate a statistically significant trend.
• Results reflect data availability, which vary significantly across regions and over time.

Temporal coverage
1980-2021 (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).