Introduction for the SI “Understanding the Baltic Sea”

Estuarine, Coastal and Shelf Science 195 (2017) 1e3 Contents lists available at ScienceDirect Estuarine, Coastal and Shelf Science journal homepage: www.elsevier.com/locate/ecss Introduction for the SI “Understanding the Baltic Sea” The Baltic Sea is a semi-enclosed sea with a low salinity, slow changing the oceanographic conditions and influencing marine water exchange and distinguished stratification. Natural properties environment. Changes in the oceanographic situation are reflected of the Baltic thus promote development of anoxic areas at the deep- in the cold intermediate layer (CIL) of the Baltic Proper. It has been est parts of the sea. In addition, the coasts of the Baltic Sea are found that CIL is heterogenous and has three basic elements with heavily populated - 85 million inhabitants living in the drainage ba- differing salinity and temperature. Probably CIL should be consid- sin and 9 countries surrounding the sea, most of them highly indus- ered not as a seasonal phenomena but as a permanent process of trially developed. Anthropogenic activities consequently add water exchange (Stepanova, 2017). considerable pressure on the already vulnerable environment of Continuous freshwater input and shallow depth are features the sea. Eutrophication, over-fishing and changed food-web, oil typical for the Baltic Sea coastal areas known also as the most com- pollution, occurrence of hazardous substances, damage of seafloor plex zones of the sea. Effort to estimate linkage between freshwater by trawling and construction works are all present in the Baltic Sea. and marine ecosystems on the level of trophic network is depicted Therefore to keep the ecosystem of the Baltic Sea viable and to by Arturas Razinkovas-Baziukas and co-authors. A macroscopic satisfy economic needs of the population at the same time, a food web network for the exposed sandy coastal zone of the continuous research on marine environmental processes is of south-eastern Baltic Sea was reconstructed to assess the matter utmost importance. Obtained knowledge then should be incorpo- and energy balance in the ecosystem and incorporating 40 living rated into sound management, coordinated on international scale. functional groups. The results indicate net heterotrophy of the Neither proper information nor valid expertise can be based on coastal zone due to strong influences from the nearby river - lagoon vague and quickly driven assumptions. The Baltic Sea countries system (Curonian Lagoon). The majority of fish species and water- are well aware of these needs and series of international science birds were present in the coastal system on a seasonal basis and congresses devoted to holistic understanding of the sea has been their migrations contributed to heterotrophic conditions. There started in 1996. was a clear negative balance for the biomass of small marine The 10th Baltic Sea Science Congress (BSSC) “Science and inno- pelagic fishes such as smelt, sprat and Baltic herring which repre- vation for future of the Baltic and the European regional seas” was sent the main prey items in this system (Razinkovas-Baziukas held in Riga, Latvia, during 15e19 June 2015 and aimed at empha- et al., 2017). sising the importance of coastal seas for inhabitants of their shores. BSSC also was a forum for presenting the results of large Health of the Baltic Sea largely depends on the activities at its research cooperation event in the northern part of the Baltic Sea catchment area as the sea receives a considerable freshwater input. e the international Gulf of Finland year 2014. In this volume results More than 250 rivers inflow into the Baltic Sea bringing nutrients, on detailed oceanographic studies in the Gulf of Finland are hazardous substances, new species to the sea. Thus the manage- included by Madis Jaak Lilover on observed flow variability and ment and governance activities should ensure the sustainable de- by Urmas Lips on wind-driven residual circulation. Different flow livery of ecosystem services and their resulting societal benefits regimes are present along the thalweg of the elongated basin in from the sea while at the same time protecting and enhancing summer and in winter, depending on the dominant wind regime the natural marine structure and functioning. during the respective year. In the vertical the flow exhibits a layered Selection of papers included in this special issue represent both structure in both the winter and summer seasons. On the coastal achievements in scientific understanding of the Baltic Sea and slopes the speed of the currents are lower than in the thalweg re- accomplished innovations in the research of the sea. gion, and they decay with depth (Lilover et al., 2017). Wind events A novel study on sea spray aerosoles by Markuszewski et al. influenced also vertical stratification in the Gulf of Finland. When (2017) reveals the difference of areosol generation and estimation strong and long enough, they caused a collapse of vertical stratifica- between the Baltic Sea and oceanic waters. Three different sea tion. A saltwater wedge in the near-bottom layer penetrated ac- spray generation models are compared - two based on whitecaps cording to the cumulative wind stress and determined the analysis and the third based on in-situ gradient measurements nutrient conditions in the near-bottom layer. The lateral transport with the function dependent on wind speed. of phosphorus, strengthened vertical stratification in the Northern The two first models occur to be insufficient as the research Baltic Proper and suggested increase in the frequency of stratifica- shows strong relation between aerosol emission and wind speed tion collapses in the Gulf of Finland in winter predict that the eutro- history. Aerosol fluxes are still one of the least understood and phication effects would not diminish significantly in this estuary in investigated issues in the Baltic Sea atmospheric studies and the nearest future (Lips et al., 2017). regional climate. Seabed and sediments are between the most explored and At the very beginning of 2015 an outstanding phenomena - researched compounds of marine ecosystem and the Baltic Sea is large-scale inflow of saline water was observed in the Baltic Sea, not an exception. Several geological studies are also part of this http://dx.doi.org/10.1016/j.ecss.2017.07.021 0272-7714/© 2017 Published by Elsevier Ltd. 2 A. Ikauniece et al. / Estuarine, Coastal and Shelf Science 195 (2017) 1e3 issue discussing the features of sediment formation and transport assessing the feasibility of remote sensing of dispersed oil in in the Southeastern Baltic e may it be impact of quasi- seawater has been taken by performing radiative transfer simula- geostrophic currents and waves (by Golenko et al.), distribution tions in visible band for natural seawater in the coastal zone of patterns of heavy-mineral-rich sand (Pupienis et al.) or interaction the Southern Baltic Sea and for a model of polluted seawater. The with coastal vegetation (Buynevich et al.). Intense quasi- results of radiative transfer modelling showed that the typically geostrophic currents may cause very high velocities in the near bot- considered concentration of 1 ppm of oil droplets can locally affect tom layer so that the elution of bottom sediments and transport of the remote sensing reflectance, causing up to a 6-fold increase or 2- their fine fractions occurs. The effect of elution can intensify due to fold decrease, depending on the droplet size distribution. It was the generation of inertial internal waves penetrating into the bot- demonstrated that the optically significant oil droplet sizes are tom layer. Areas with the highest velocities that were formed under <100 mm, as long as oil concentration does not exceed 5 ppm the western and northeastern winds in most cases coincide with (Haule et al., 2017). New data on the use of red macroalga Ceramium the areas where the bottom sediments are presented by coarse frac- tenuicorne growth inhibition test are compiled on toxicity of single tions: gravel and sands (Golenko et al., 2017). An option to assess substances, waste waters from pulp mills, leachates from anti- the patterns of longshore transport is to estimate heavy-mineral fouling paints, harbour sediments and soil used for maintenance concentration (HMC) trends and grain-size statistical parameters of leisure boats. The growth inhibition test is a robust test that as indicators. So an existence of a longshore particle flux is sug- has high repeatability and reproducibility and easily can be applied gested at the Curonian spit and temporally constrained HMC distri- on water, soil and sediment samples without being too costly. The bution along the middle of the beach reflects the cumulative effect overall results show that contaminants from boat activities and the of antecedent geologic framework, longshore sediment transfer, use of antifouling paints in particular pose a threat to the environ- erosional and accretionary processes, wave and wind climate, and ment (Eklund, 2017). local coastal protective structures (Pupienis et al., 2017). Curonian Studies of this volume indicate that although the Baltic Sea is spit is also famous for its dunes and when explored with ground- considered to be one of the best studied seas in the world, there penetrating radar (GPR), interaction of windblown sand and vege- is still place for applying new approaches, investigating less known tation becomes visible. Along the Curonian Spit, Lithuania, dune elements of the ecosystem and producing new knowledge for sus- reactivation phases resulted in massive invasion of siliciclastic tainable use of marine resources. The role of natural (and also so- sand triggered by natural perturbations and land clearance. cial) sciences is to formulate research questions and seek the Massive (>30 m high) dunes entombed mature pine, oak, and alder answers in order to inform and guide human actions. In the case stands and this process is ongoing. Mid-frequency (200 MHz) of the Baltic Sea science and scientists have to engage in the georadar surveys reveal landwarddipping lateral accretion surfaces decision-making process for the safe future of marine environment. interrupted by high-amplitude pointsource anomalies produced by Cross-border cooperation of interdisciplinary research should be recently buried trees (Buynevich et al., 2017). the backbone of the upcoming Baltic Sea science. Benthic substrates and their inhabitants are also successfully used for developing novel research approaches as demonstrated in a study by Andis Kalv
ans on significance of grain-size of varved References clays when studying the history of the Baltic Sea or in the attempt by Josephine Emma and co-authors to capture genetic diversity of Buynevich, I., Savarese, M., Curran, H.A., Bitinas, A., Glumac, B., Pupienis, D., Karen Kopcznski, K., Dobrotin, N., Gnivecki, P., Park Boush, L., Damusyte, A., 2017. Sand blue mussel populations. The grain size distribution of varved gla- incursion into temperate (Lithuania) and tropical (the Bahamas) maritime vege- ciolacustrine sediments was tested as a proxy for estimation of the tation: georadar visualization of target-rich aeolian lithosomes. Estuar. Coast. water depth and the duration of winter in glacial varves from Shelf Sci. 195, 69e75. Pa€rnu. The coarsest particle size found on top of the winter layer Eklund, B., 2017. Review of the use of Ceramium tenuicorne growth inhibition test for testing toxicity of substances, effluents, products sediment and soil. Estuar. is calculated for each varve from measured grain size distributions Coast. Shelf Sci. 195, 88e97. using a novel methodology and compared to the reconstructed wa- Emma, J., Larsson, B., Lind, E., Corell, H., Grahn, M., Smolarz, K., Lo € nn, M., 2017. ter depth of the Baltic Ice Lake to constrain the likely duration of the Regional genetic differentiation in the blue mussel from the Baltic Sea area. Estuar. Coast. Shelf Sci. 195, 98e109. winter. The average constrained winter length was close to the Golenko, M.N., Golenko, N.N., Emelyanov, E.M., Nekrasov, M.A., 2017. Role of quasi- duration of a calendar year (Kalva
ns et al., 2017). An innovative geostrophic currents and inertial waves in elution of fine sediments in the combination of various methods - high-resolution genetic markers, southeastern part of the Baltic. Estuar. Coast. Shelf Sci. 195, 60e68. Haule, K., Freda, W., Darecki, M., Toczek, H., 2017. Possibilities of optical remote species hybridization data and biophysical modeling - allows to sensing of dispersed oil in coastal waters. Estuar. Coast. Shelf Sci. 195, 76e87. have a comprehensive picture of the evolutionary landscape for a Kalva
ns, A., Hang, T., Kohv, M., 2017. Grain-size of varved clays from the north- keystone species in the Baltic Sea, the blue mussel. Distinct genetic eastern Baltic Ice Lake: insight to the sedimentary environment. Estuar. Coast. Shelf Sci. 195, 51e59. differentiation between the West Coast, Baltic Proper and Bothnian Lilover, M.-J., Elken, J., Suhhova, I., Liblik, T., 2017. Observed flow variability along Sea regions, with lower gene diversity in the Bothnian Sea has been the thalweg, and on the coastal slopes of the Gulf of Finland, Baltic Sea. Estuar. found. Oceanographic connectivity together with salinity and to Coast. Shelf Sci. 195, 23e33. Lips, U., Laanemets, J., Lips, I., Liblik, T., Suhhova, I., Suursaar, Ü., 2017. Wind-driven some extent species identity provides explanations for the genetic residual circulation and related oxygen and nutrient dynamics in the Gulf of differentiation between the West Coast and the Baltic Sea (Baltic Finland (Baltic Sea) in winter. Estuar. Coast. Shelf Sci. 195, 4e15. Proper and Bothnian Sea), while the poorer connectivity to the Markuszewski, P., Kosecki, S., Petelski, T., 2017. Sea spray aerosol fluxes in the Baltic Bothnian Sea may explain the lower gene diversity (Emma et al., Sea region: comparison of the WAM model with measurements. Estuar. Coast. Shelf Sci. 195, 16e22. 2017). Pupienis, D., Buynevich, I., Ryabchuk, D., Jarmalavi  cius, D., Zilinskas, G., Fedorovi c, J., In addition to gaining more knowledge on environmental pro- Kovaleva, O., Sergeev, A., Cichon-Pupienis, A., 2017. Spatial patterns in heavy- cesses the protection and conservation aspect of the Baltic Sea shall mineral concentrations along the Curonian Spit coast, southeastern Baltic Sea. Estuar. Coast. Shelf Sci. 195, 41e50. never be forgotten and innovations are in place there. Use of remote Razinkovas-Baziukas, A., Morku
ne, _ R., Bacevi
naite, cius, E., Gasiu _ Z.R., 2017. Trophic optical sensing in detecting oil pollution by Kamila Haule and Network Model of Exposed Sandy Coast: Linking Continental and Marine Water further development of red algae as ecotoxicological indicator by Ecosystems, 195, 110e123. Stepanova, N., 2017. Vertical structure and seasonal evolution of the cold interme- Britta Eklund are examples included in this issue. The first step in diate layer in the Baltic Proper. Estuar. Coast. Shelf Sci. 195, 34e40.  A. Ikauniece et al. / Estuarine, Coastal and Shelf Science 195 (2017) 1e3 3 Anda Ikauniece, Guest Editor* Laimdota Kalniņa, Guest Editor Latvian Institute of Aquatic Ecology, Voleru 4, Riga LV1007, Latvia University of Latvia, Jelgavas 1, Riga LV1004, Latvia E-mail address: laimdota.kalnina@lu.lv. H.E. Markus Meier, Guest Editor Swedish Meteorological and Hydrological Institute, SE-601 76 * Norrko €ping, Sweden Corresponding author. E-mail address: Markus.Meier@smhi.se. E-mail address: anda.ikauniece@lhei.lv (A. Ikauniece).