a53ad03f-3938-9383-3831-000000098111 Ifremer Centre de Nantes Rue de l'Ile d'Yeu BP 21105 NANTES CEDEX 3 44311 France Relations publiques : Morgan.Le.Moigne@ifremer.fr https://wwz.ifremer.fr/atlantique web site 2026-04-02T00:00:00 ISO 19115:2003/19139 1.0 WGS 1984 Map of Chlorophyll a concentrations trend between 1998 and 2019 in the Gulf of Biscay 2023-11-28 2024-06-26 2024-12-19 a53ad03f-3938-9383-3831-000000098111 DOI:10.17882/98111 Huguet Antoine (2023). Map of Chlorophyll a concentrations trend between 1998 and 2019 in the Gulf of Biscay. SEANOE. https://doi.org/10.17882/98111 For the 21 years of the study, an examination of trends in chlorophyll concentration revealed a general decline throughout the Gulf over the production period. These trends, extracted from dynamic linear model, also allowed this decline to be quantified. Expressed as a percentage, a large part of the area below the 50 m bathymetric line showed a decrease of at least 10% over the period, corresponding to a value of at least 0.1 µg.l-1. However, the spatial distribution reveals some more local phenomena. In southern Brittany, from Quimper to Vannes, a particular feature appears, with an upward trend over several kilometres along the coast, followed by a pronounced gradient along the coast. This gradient includes a zone where a continuous monotonic increasing trend is observed, then a zone where the trend becomes not significant and finally, about 15 km from the coast, a new zone where a significant continuous monotonic decreasing trend is observed. The increase in chlorophyll a concentration in the very coastal part is greater than 0.1 µg.l-1 over the period. Another peculiarity concerns the central part, located at the edge of the plateau at Cap Ferrat and Pente Aquitaine, where an increase in chlorophyll a was observed, but the variations remained small, being less than 0.1 µg.l-1. About a hundred kilometres south-west of Saint Nazaire, an area of about 40 by 50 km shows a decrease in chlorophyll a of more than 20%, quantified as more than 0.1 µg.l-1 over the period. Important Note: This submission has been initially submitted to SEA scieNtific Open data Edition (SEANOE) publication service and received the recorded DOI. The metadata elements have been further processed (refined) in EMODnet Ingestion Service in order to conform with the Data Submission Service specifications. SEA scieNtific Open data Edition By address: IFREMER / IDM / SISMER - Scientific Information Systems for the SEA, IFREMER Centre de Bretagne, ZI Pointe du diable CS 10070 PLOUZANE 29280 France data@seanoe.org https://www.seanoe.org/ web site Ifremer, Scientific Information Systems for the sea IFREMER Centre de Bretagne ZI Pointe du diable CS 10070 PLOUZANE 29280 France sismer@ifremer.fr https://data.ifremer.fr/Centre-de-donnees web site Ifremer, Scientific Information Systems for the sea IFREMER Centre de Bretagne ZI Pointe du diable CS 10070 PLOUZANE 29280 France sismer@ifremer.fr https://data.ifremer.fr/Centre-de-donnees web site Oceanographic geographical features GEMET - INSPIRE themes, version 1.0 2008-06-01 geonetwork.thesaurus.external.theme.httpinspireeceuropaeutheme-theme North Atlantic Ocean Atlantic Ocean European mainland Northeast Atlantic Ocean (40W) SeaVoX salt and fresh water body gazetteer 2024-01-15 SeaVoX salt and fresh water body gazetteer Pigments SeaDataNet Agreed Parameter Groups 2023-07-04 SeaDataNet Agreed Parameter Groups radiometers SeaDataNet device categories 2024-01-16 SeaDataNet device categories SeaVoX Device Catalogue 2024-01-29 SeaVoX Device Catalogue Chlorophyll pigment concentrations in water bodies SeaDataNet Parameter Discovery Vocabulary 2023-12-12 SeaDataNet Parameter Discovery Vocabulary CRUISE SUMMARY REPORT INVENTORY (CSR) 2023-10-02 satellite SeaVoX Platform Categories 2024-01-16 SeaVoX Platform Categories ICES Platform Codes 2024-01-16 ICES Platform Codes EUROPEAN DIRECTORY OF MARINE ENVIRONMENTAL RESEARCH PROJECTS (EDMERP) 2020-06-05 Delimited MEDIN data format categories 2024-01-29 MEDIN data format categories World Register of Marine Species (WORMS) 2024-02-07 SeaDataNet Measurement Periodicity Categories 2024-01-29 SeaDataNet Measurement Periodicity Categories BODC-approved data storage units (Spatial Unit) 2023-10-12 BODC-approved data storage units (Spatial Unit) BODC-approved data storage units (Vertical Unit) 2023-10-12 BODC-approved data storage units (Vertical Unit) no limitations to public access Conditions for access and use apply CC-BY 4.0 Oceans 1998-01-01 2019-12-31 -7.915473 0.173522 40.457753 48.708403 Delimited 1 https://cloud.emodnet-ingestion.eu/index.php/s/jiYqpwHsIWzCwpa WWW:DOWNLOAD-1.0-http--download WWW:LINK-1.0-http--link COMMISSION REGULATION (EC) No 1205/2008 of 3 December 2008 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards metadata 2010-12-08 See the referenced specification false Corrigendum to INSPIRE Metadata Regulation published in the Official Journal of the European Union, L 328, page 83 2010-12-08 See the referenced specification false Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services 2010-12-08 See the referenced specification false Processed data|For the 21 years of the study, an examination of trends in chlorophyll concentration revealed a general decline throughout the Gulf over the production period. These trends, extracted from dynamic linear model, also allowed this decline to be quantified. Expressed as a percentage, a large part of the area below the 50 m bathymetric line showed a decrease of at least 10% over the period, corresponding to a value of at least 0.1 µg.l-1. However, the spatial distribution reveals some more local phenomena. In southern Brittany, from Quimper to Vannes, a particular feature appears, with an upward trend over several kilometres along the coast, followed by a pronounced gradient along the coast. This gradient includes a zone where a continuous monotonic increasing trend is observed, then a zone where the trend becomes not significant and finally, about 15 km from the coast, a new zone where a significant continuous monotonic decreasing trend is observed. The increase in chlorophyll a concentration in the very coastal part is greater than 0.1 µg.l-1 over the period. Another peculiarity concerns the central part, located at the edge of the plateau at Cap Ferrat and Pente Aquitaine, where an increase in chlorophyll a was observed, but the variations remained small, being less than 0.1 µg.l-1. About a hundred kilometres south-west of Saint Nazaire, an area of about 40 by 50 km shows a decrease in chlorophyll a of more than 20%, quantified as more than 0.1 µg.l-1 over the period.