Gulf of Finland Pilot Supersite

Main characteristics of the Baltic Sea

The BALTIC SEA (to which the Gulf of Finland is a subpart) is seasonally ice covered, enclosed and brackish sea area, with harsh climatic conditions, and it is affected by various anthropogenic pressures. Riverine load of nutrients, dissolved carbon and freshwater largely modifies the coastal ecosystems. The salinity gradient shapes the physical, chemical and biological characteristics of the sea area. The seasonal thermocline and permanent halocline separate water layers and affect the vertical fluxes and biogeochemical cycles, and form barriers reducing the atmospheric forcing.

The Baltic Sea is highly productive, due to its high nutrient load, and several areas suffer from eutrophication, related algae blooms, and shifts in species composition and ecosystem functioning. As a combination of high algae production, high sedimentation, and reduced mixing, large areas with anoxic bottoms have developed. Oxygen depletion in the seafloor is accompanied by a release of inorganic nutrients. Occasional intrusions of oxygen-rich high saline water from the North Sea ventilate the deep parts of the Baltic Sea, reducing the extent of anoxic bottoms. Sub-basin differences in alkalinity loads lead to different buffer capacities and an increase of alkalinity over the last decades might partly mitigate the effect of acidification. Climate change, increasing the occurrence of mild winters, intensifies carbon load from land, affecting also carbon cycling, the balance of autotrophy vs. heterotrophy and brownification, all having cascading effects in the ecosystem.

Map showing the key GoF PSS sustained platforms. Red lines represent FerryBox lines, stars are for profiling buoys, EX stands for experimental facility or calibration lab and the orange oval symbol is for Utö Atmospheric and Marine Station.

Platforms in Gulf of Finland Pilot Supersite

Operational observation systems & platforms in the region   Operational status  Parameters
FerryBox: Silja Serenade and Finnmaid (SYKE, FMI, IOW), Silja Europa (TALTECH) Operational (Silja Serenade and Silja Europa not running at the time of writing 11/2020 due to Covid) T, S, Chla-Fluo, CDOM-Fluo, Turbidity, Phycocyanin-Fluo, Phycoerythrin-Fluo, O2, pH, CO2, sampler
Utö Observatory (FMI, SYKE), Keri Observatory (TALTECH) Operational Utö: T, S, Chla-Fluo, CDOM-Fluo, Turbidity, Phycocyanin-Fluo, O2, pH, CO2, Meteorology, IFCB, Cytosense, FRRF, discrete samples
Keri: T, S, Chla-Fluo, Turbidity, Phycocyanin-Fluo, O2, Meteorology
Gliders (FMI, TALTECH) Operational  T, S, Chla-Fluo, CDOM-Fluo
Argo floats (FMI) Operational T, S, Chla-Fluo, O2
Profiling buoys (FMI, SYKE, TALTECH) Operational, some components under maintenance T, S, Chla-Fluo, CDOM-Fluo, O2, Phycocyanin-Fluo
Wave riders (TALTECH, FMI) Operational Wave height
Monitoring by R/V (All). Occasional Annual program with several cruises & stations in the GoF area. 
Experimental and calibration facilities (SYKE) As needed  

Actions

There are 10 actions for the Gulf of Finland Pilot Supersites.

Action # Title Objective
1 Harmonised observations The Action aims in improving the harmonisation of GoF PSS data, produced by various institutes. Such harmonisation is the first step in merging data from different sources and the creation of consistent datasets for multiple uses. Harmonisation protocols are demonstrated especially for observations on phytoplankton communities, HABs, oxygen, and carbonate system dynamics. Shared management actions and communication schemes, and joint QC/QA practices for key observations will allow unified data flows and products, which will also facilitate their discovery, access, and use.
2 The performance of operational forecast models  The Action will analyse and disseminate discrepancies in hydrography and biogeochemistry between in-situ and CMEMS operational forecast model products at the GoF PSS. The main outcome of the topic is the conclusive report of the model performances in the area. Possible sources of the discrepancies will be discussed and instructions for users of the products will be provided.
 3 Optical data for Ocean Color product validation Ocean Colour algorithm development and product validation benefit largely from in situ measurements of optically active compounds, their concentrations and/or specific optical properties, and match-up (synoptic) measurements at different sites. Key challenges with some optical sensors (fluorescence, turbidity) are that results are not clearly traceable and in effect they are represented in the relative scale. The lack of standards for sensors and their calibration and validation make the intercomparison between sensors difficult. This task builds on the results of GoF PSS #1, inter-calibration between sensors, and improved QC. It provides Regional Data, as consistent as possible within technological limits, to Ocean Colour groups for evaluation. 
 4 Detection of cyanobacterial blooms The Action aims to improve transnational and trans-institutional joint observations for HAB detection and creating concepts and mechanisms for sharing the information and production of HAB reviews. The task will gather comparable and complementary data to analyse spatiotemporal variability of cyanobacteria blooms in the Gulf of Finland. The collected online data will support weekly HAB reviews, carried out by SYKE. These reviews are targeted for public and different marine users and are distributed through SYKE web pages and press releases. The concept of HAB reviews will be demonstrated to other partners within the PSS and between PSSs. In addition, QC data will promote scientific analyses of the causes and consequences of the blooms. 
 5 Mapping the deep-water oxygen conditions  Sub-surface oxygen conditions in the Gulf of Finland are very sensitive to atmospheric forcing. The area occupied by hypoxic water varies between 0 – 7000 km2 and considerable changes can occur within a few days, i.e. in much shorter time scales than conventional monitoring can capture. The main aim of the topic is to estimate oxygen distribution in the gulf with at least weekly temporal resolution. Latter allows calculation of statistics of the near-bottom oxygen conditions.
Biological interplay with the carbonate system Eutrophication, and with it changes in primary production and mineralization, are of major concern for the Baltic Sea and the GoF PSS area in particular. The inorganic carbon cycle can be used as a powerful quantitative indicator in this complex interplay, as it is the major constituent of organic biomass, and the oxidation of organic carbon is by far the largest contributor to the oxygen demand in deeper waters. It becomes more and more evident that not only the summer N-fixation period but also the later part of the spring bloom show high variability in C/N/P ratios, thus the link of production of biomass to oxygen demand requires tracing of the carbon cycle. Homogenization of data flows and data quality, the definition of gaps, and integrated assessment and interpretation are essential to make full use of these data for ecosystem assessment in the GoF PSS target area.
 7 Forecast models for cyanobacterial blooms Forecast modelling of cyanobacteria growth and their blooms are challenging tasks but there is a growing demand for such action. Depending on the time horizon, different modelling tools may be used. Long-term scenario models (months) are based on ecosystem models supported by observations of nutrients as a key driver of blooms and expert opinions. The short-term models (days-weeks) may include more detailed parameterization of cyanobacteria vs. other algae groups and taking into account the weather as key drivers. This Action will analyse the performance of the forecast models for cyanobacterial blooms in the Gulf of Finland by comparing to in-situ data obtained from the GoF PSS. Estimate the performance and greatest challenges of the current models and develop ideas on how the models could be advanced.
 8 Extreme events affecting phytoplankton – AQUACOSM collaboration I  Plankton ecosystem reacts rapidly to the shifts in various environmental pressures. These responses may be tracked using high-resolution observations with state-of-art sensors, but still many of the interactions in the planktonic realm may remain hidden. For example, rate measurements and food web interactions are hard to measure without enclosing the plankton communities for the period when measurements are done. As well, understanding the responses of planktonic systems to some specific perturbations may require that part of the ecosystem is isolated and studied experimentally. This topic will study how the Baltic Sea phytoplankton communities are affected by extreme climatic forcing, in collaboration with experimental work of AQUACOSM-plus and supported by long-term observational data.
 9 Promotion of the use of PSS data and products  Aims of PSSs are to harmonize regional observations, integrate transnational operations, jointly steer data collection, provide joint products with added value and to connect to other regions. Such actions have a strong need for regional coordination, which is not only the task for JERICO-RI, but also other regional initiatives. This action will disseminate the results from GoF PSS to major regional actors and ask for their feedback to develop observation strategies further. The integrated coastal observations done within GoF PSS, as well as the overall sampling strategy of coastal JERICO-RI Supersites, will be communicated to regional actors, especially HELCOM, EUBSR, and BOOS. 
 10 Connecting the other RIs in the region  Many of the Grand Environmental Challenges affect several environmental domains (land-sea-air) and cannot be studied in isolation within one domain only. Streamlining observations, experimentation, and data analysis within European RI-landscape requires that regional and practical bottom-up collaborations between RIs develop parallel to higher level and strategic top-down collaborations (which are dealt in WP2). Connecting RIs at the regional level will highlight existing synergies, helps to identify overlaps and research topics where collaboration needs to be strengthened. Specifically, in GoF PSS we seek to establish connections to other RIs by contributing to carbonate system measurement guidelines for coastal seas (ICOS ERIC), sharing data (AQUACOSM-plus, EURO-ARGO ERIC, ICOS ERIC), and seeking possibilities for future joint activities (ACTRIS PPP, EMBRC-ERIC, EUROFLEETS+, MINKE).