About this Research Topic
The Baltic Sea is a geologically and evolutionary young coastal ocean that in its past underwent several severe environmental changes. Environmental gradients, both horizontal and vertical, characterise the present Baltic Sea. A west to east surface salinity gradient (south to north, respectively) from 24 in Kattegat to nearly freshwater conditions in the Bothnian Bay, and in particular a vertical salinity and oxygen gradient resulting in a stratification which causes hypoxic and sulfidic anoxic deep basins. These gradient systems undergo natural and anthropogenically impacted changes due to varying physico-chemical driving forces. They have an imprint both on structure and function of the biological systems and influence on biogeochemical cycling. Besides, coastal seas in general and the Baltic Sea in particular, undergo constant and direct influence from land with consequences to matter cycles, biogeochemical interactions, energy fluxes and sediment dynamics. Today’s important question is which of the effects, which we can detect, occur naturally, and which are stimulated by human activities. Deciphering past environmental changes and their causes provide keys to understand and simulate possible future scenarios - all of it relevant for societal awareness and the consecutive implementation of marine and coastal policies.
Under the Research Topic “Living along gradients: past, present, future” we are aiming to discuss:
• contributions to the dynamics of gradient systems,
• study results on processes that affect the coastal sea systems and on the results of interaction between coastal seas and society,
• the detection or reconstruction of past and present changes on time scales from interannual to millennial,
• future change models.
We would like to especially encourage interdisciplinary contributions and those tackling the following crosscutting topics:
Hypoxia: Hypoxia is one of the most severe threats to the Baltic Sea. To thoroughly understand all related processes is an ongoing task, especially what determines the extent and duration of oxic-hypoxic conditions. We are looking for new results explaining the development of hypoxic areas as well as for reports on process studies at hypoxic-oxic boundaries.
Major Baltic Inflows: Contributions regarding processes and phenomena associated with recent salt-water inflows are requested: The major salt-water inflows starting in 2014 had different effects compared to such major inflow events in the past. What happened following this inflow? How did the small inflow events following later change the effects (geographically and in terms of geochemistry) of the major inflow.
Monitoring and Assessment: Contributions highlighting new monitoring and assessment concepts and the necessary tools for implementing them are requested. This may include modelling, operational oceanography and observational approaches like sensor development and in situ technology, autonomous and moored technology, gliders, ROVs, remote sensing, and general contributions to new monitoring strategies.
Influences of the catchment: Contributions considering land-ocean interactions including hydrology are welcome: role of coastal processes influencing enclosed marine systems, and vice versa; effects of ground water inflow and river drainage to matter fluxes on changes in system structure and subsequent variations in energy budget; effects of riverine nutrient inputs and eutrophication, atmospheric inputs; regional differences of these processes in the Baltic Sea.
The Topic Editors declare that they are part of a large collaborative network working on the Baltic Sea.
Keywords: Baltic Sea research, coastal seas research, hypoxia, Major Baltic Inflow, eutrophication
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.