ReviewOCEANOGRAPHY

The Baltic Sea as a time machine for the future coastal ocean

See allHide authors and affiliations

Science Advances  09 May 2018:
Vol. 4, no. 5, eaar8195
DOI: 10.1126/sciadv.aar8195
  • Fig. 1 The Baltic Sea time machine.

    (A) The Baltic Sea, its neighboring countries, and the catchment area. (B) Sea surface temperature (SST) change per decade since 1980. The Baltic Sea is at the center of the map. (C) Left: High-resolution surface seawater CO2 variability in 2014 at a coastal Baltic Sea site (Kiel Fjord Time Series, 54.2°N, 10.9°E; red symbols) in comparison to an oceanic site close to Hawai’i (Woods Hole—Hawaii Ocean Time-series Site, 22.7°N, 157.9°W; blue symbols) and coastal sites in Florida (Cheeca Rocks, 24.9°N, 80.6°W), California [California Current Ecosystem Mooring 2 (CCE2), 34.3°N, 120.8°W; green symbols], Alaska (Kodiak, 57.7°N, 152.3°W; black symbols), and Washington (Twanoh, 47.4°N, 123°W; orange symbols). Right: Mean Pco2/xco2 values and SD for 2014 data from selected time series stations (see above). All data are seawater (SW) Pco2 (in microatmospheres) except for station Twanoh [xco2, in parts per million (ppm), dry]. Kie, Kiel; Twa, Twanoh, Kod, Kodiak; Cal, CCE2; Che, Cheeca Rocks; Haw, Hawai’i. (D) Expansion of hypoxic zones in the Baltic Sea during 115 years of monitoring. Black shading shows the situation for the period 1900–1910, whereas red shading indicates the period 2001–2010. Coastal hypoxia is depicted by red dots. For data sources, see data S3.

  • Fig. 2 Examples of long-term time series available for the Baltic Sea.

    (A) Temperature (0 to 10 m). (B) Pco2 in the bottom waters (>150 m) for station BY15 in the central Gotland Basin. (C) Secchi depths after Baltic Sea Environmental Proceedings no. 133. (D) Benthic area with anoxic conditions (<2 mg O2 liter−1). (E) Abundance of cyanobacteria in the Gulf of Finland. (F) Abundance of zooplankton (Acartia spp.) in Pärnu Bay, Estonia. (G) Eastern Baltic cod total spawning stock biomass. (H) Herring total spawning stock biomass data. (I) DDT concentration in liver of sea eagles. (J) Counts of NIS. Green-, red-, and blue-colored areas indicate the time period when policies for fisheries management, the reduction of nutrients, and the ban of DDT were implemented, respectively. For data sources, see data S3.

  • Fig. 3 Governance structure in the Baltic Sea region.

    (A) Baltic fisheries management is an exclusive EU competence under the Common Fisheries Policy (2013). Fishing is based on the maximum sustainable yield principle resulting in total allowable catches (TACs) and national quotas. TACs are developed in a process involving the following steps: Advice from stakeholder groups is collected by Advisory Councils (ACs), and scientific advice is provided by ICES and communicated to the EU Commission by the EU Scientific, Technical, and Economic Committee for Fisheries (STECF). The EU Commission suggests TACs to the EU Council of Ministers that makes the final decisions. On the basis of the TACs, national quotas are distributed, implemented, and monitored by member states. Bilateral agreements integrate Russia into the EU environmental management. (B) In the management of hazardous substances, HELCOM carries a significant role for monitoring, assessing, and agenda setting, whereas the EU provides legal basis and enforcement. HELCOM works through its recommendations, the BSAP, and ministerial declarations. The EU has addressed the issue via, for example, the Registration, Evaluation, Authorization and restriction of Chemicals (REACH) regulation, the Marine Strategy Framework Directive (MSFD), and the Water Framework Directive (WFD). The EU Commission initiates and proposes new legislation to be approved by both the Council of Ministers and the European Parliament. The EU and HELCOM closely interact. For example, the BSAP was initiated in 2007 following the EU MSFD. ICES provides scientific data to HELCOM and was involved in the development of the MSFD. (C) Governance of eutrophication. HELCOM targets the sources of eutrophication via several recommendations (for example, Rec 28E/4 on measures to hinder land-based pollution) and the BSAP with reduction targets for emissions of nitrogen and phosphorus. EU has adopted several directives to deal specifically with eutrophication including the Urban Waste Water Treatment Directive (UWWTD), the Nitrate Directive (ND), and the National Emission Ceilings Directive (NECD). The EU Common Agricultural Policy (CAP) strongly influences nutrient management. Within the CAP, member states implement specific agricultural measures targeted at nutrient reduction from agriculture that (partly) reflect measures recommended by HELCOM. For detailed references and sources, see data S3.

  • Fig. 4 Nutrient input into the Baltic Sea.

    Five-year moving average values of N and P loads (in 1000 metric tons per year) to the Baltic Sea together with the BSAP targets. Along the x axis, the timing of countries joining the EU and the introduction of key EU environmental legislation are shown. WWTP, wastewater treatment plans; HELCOM, signing of the Helsinki Convention; UWWD, urban wastewater directive. Key developments of the EU CAP are indicated by arrows at top of the diagram. Supply mgmt, supply management; DE, Germany; DK, Denmark; SE, Sweden; FI, Finland; EST, Estonia; LIT, Lithuania; LT, Latvia; PL, Poland. For detailed references and sources, see data S3.

  • Table 1 Summary of abiotic and biotic changes in the Baltic Sea in comparison to other coastal areas worldwide.

    Red coloration in the heat map depicts drivers that are above average in severity/impact; yellow, average; and green, below average. Gray: No assessment possible. NIS, nonindigenous species. For full documentation on how scores for each system and parameter were obtained, including all references underlying the assessment, see data S1.

    SystemWarming of
    surface water
    Increased
    nutrient load
    Oxygen depletion in
    bottom waters
    Shipping intensityProportion of NISOrganochlorines
    in organisms
    Status of marine
    fish stocks
    Baltic Sea
    North Sea
    Mediterranean Sea
    Black Sea
    Gulf of Mexico
    East China Sea
    Barents Sea
  • Table 2 Summary of data availability, system understanding, and management/governance regime in the Baltic Sea compared to other coastal areas worldwide.

    Green coloration in the heat map indicates good scientific knowledge/effective management/governance structures, red denotes the opposite, and yellow indicates intermediate. For full documentation on how scores for each system and parameter were obtained, including all references underlying the assessment, see data S1.

    SystemResearch activitiesMonitoring activitiesData availability for fish
    stock assessments
    Governance
    structure
    Baltic Sea
    North Sea
    Mediterranean Sea
    Black Sea
    Gulf of Mexico
    East China Sea
    Barents Sea

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/4/5/eaar8195/DC1

    data S1. Methods and references used for the assembly of Tables 1 and 2 of the main text.

    table S1A. Detailed assessment of the qualitative status of environmental pressures/drivers in the Baltic Sea region compared to other worldwide coastal seas.

    table S1B. Detailed assessment of scientific knowledge, management regimes, and governance structures in the Baltic Sea region compared to other worldwide coastal seas/areas.

    table S2. Valuation of benefits of environmental intervention or management measurements in the Baltic Sea area.

    data S2. Box: Genetic knowledge in marine management—The recovery of Baltic salmon.

    data S3. Data sources for figures.

    References (121224)

  • Supplementary Materials

    This PDF file includes:

    • data S1. Methods and references used for the assembly of Tables 1 and 2 of the main text.
    • table S1A. Detailed assessment of the qualitative status of environmental pressures/drivers in the Baltic Sea region compared to other worldwide coastal seas.
    • table S1B. Detailed assessment of scientific knowledge, management regimes, and governance structures in the Baltic Sea region compared to other worldwide coastal seas/areas.
    • table S2. Valuation of benefits of environmental intervention or management measurements in the Baltic Sea area.
    • data S2. Box: Genetic knowledge in marine management—The recovery of Baltic salmon.
    • data S3. Data sources for figures.
    • References (121–224)

    Download PDF

    Files in this Data Supplement:

Navigate This Article