The ARCHYD dataset, which have been collected since 1988, represents the longest long-term hydrologic data sets in Arcachon Bay. The objectives of this monitoring programme are to assess the influence of oceanic and continental inputs on the water quality of the bay and their implications on biological processes. It also aims to estimate the effectiveness of management policies in the bay by providing information on trends and/or shifts in pressure, state, and impact variables. Sampling is carried on stations spread across the entire bay, but since 1988, the number and location of stations have changed slightly to better take into account the gradient of ocean and continental inputs. In 2005, the ARCHYD network was reduced to 8 stations that are still sampled by Ifremer to date. All the stations are sampled at a weekly frequency, at midday, alternately around the low spring tide and the high neap tide. Data are complementary to REPHY dataset. Physico-chemical measures include temperature, salinity, turbidity, suspended matters (organic, mineral), dissolved oxygen and dissolved inorganic nutrients (ammonium, nitrite+nitrate, phosphate, silicate). Biological measures include pigment proxies of phytoplankton biomass and state (chlorophyll a and phaeopigment). 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.

The investigations of Blekinge coast started in 1978. In 1990 the program "Blekinge Kustvattenkontrollprogram" Blekinge Coastal water control programme, was formed, building on the stations sampled earlier, but with extended sampling.

Secchi depth (m) measurements in Mersrags polygon were performed within the project "AQUAFIMA – Integrating Aquaculture and Fisheries Management towards a sustainable regional development in the Baltic Sea Region". Observations were made at a potential fish spawning and nursing site in the coastal area near Mersrags in August -September 2013.

Secchi depth (m) measurements in Skulte polygon were performed within the project "AQUAFIMA – Integrating Aquaculture and Fisheries Management towards a sustainable regional development in the Baltic Sea Region". Observations were made at a potential fish spawning and nursing site in the coastal area near Skulte in August -September 2013.

Weekly/biweekly monitoring of temperature, salinity, nutrients ( nitrates, nitrites, ammonnia, phosphates, DIN), sestone and chlorophyll-a in coastal waters from Sozopol Bay, Bulgarian Black Sea coast done by the Laboratory of Marine Ecology, IBER-BAS.

Monthly monitoring data of physico-chemical parameters of the water column in the coastal zone of Burgas Bay, Bulgaria

Physical ( temperature, salinity, turbidity), chemical (nitrites, nitrates, ammonia, DIN, phosphates) and biological ( chl-a) in Sozopol Bay, Black Sea. Data collected in the framework of the BalkanMed RECONNECT project ( 2017-2020)

Data from paper mill in the Baltic between 2006-2012

Data from paper mill between 2013-2017.

The dataset include expeditionary materials of Secchi data for the Baltic sea -cruise 5004920.