Q Is there disagreement within the research community as to whether we have the right to interfere with the ecosystem of the Baltic Sea. What’s your view on this?
A The Baltic Sea has been subject to different anthropogenic activities already several decades or even longer: nutrient load from activities on land, dredging and constructions, marine traffic etc. We should be able to use all efforts to fix the damage caused by this activity, and, therefore, also the measures taken in the sea should at least be investigated as potential means to help the ecosystems of the Baltic Sea to recover.
Q What are the benefits and risks in sea-based measures?
A Only few of the sea-based measures discussed have been actually tested in marine environment. Therefore, the benefits can only be evaluated when there is enough information existing on potential effects. In small scale pilot tests, environmental risks remain very local and relatively low, as long as pilot locations are thoroughly monitored, and their selection is based on environmental criteria. Other risks, e.g. related to financing, will be evaluated based on the results from pilot tests.
Q What are the main measures that can be used to reduce the nutrient load already in the Sea?
A For now, the only proven measure to remove nutrients from the sea is fishing, and when targeted to underutilized, low value species like cyprinids it can also bring added value in addition to commercial fisheries. Mussel cultivation is also being tested in several projects, but the cost-efficiency of the measure remains relatively low so far. Chemical treatment of the sediment with aluminium has been used in lakes and also in one bay in Sweden, but the measure is, however quite efficient, very expensive. In addition, oxygenation of deep water layer or the sediment surface has been piloted with varying results.
Some potential new measures, that are being tested in the SEABASED project, include binding phosphorus into the sediment with marl (limestone-based material) and removal of top layer of bottom sediment, which could help the natural processes to bind nutrients in the seabed.
Q Can we take any learnings from the measures that have been used to curb eutrophication in the lakes?
A Several methods for lake restoration have been utilized for decades in Finland and Sweden, e.g. management fishing, oxygenation, dredging and chemical treatment. The experiences from lakes can partly be utilized, however, the sea is a very different environment from lakes – not only by size but also by its physics, chemistry, ecology and interactive processes taking place in marine environment.
Q What is the amount of phosphorus stored in the main basin of the Baltic Sea?
Currently, there are only estimates existing, however, most researches agree on the fact that the amount of phosphorus in the main basin is significant compared to the annual phosphorus load entering the sea from land-based sources. Estimates are updated as research about this progresses.
Q What is the load from land-based sources as opposed to this tonne phosphorus bomb – which should we focus on, which is more important?
A The total land-based phosphorus load to the Baltic Sea is approximately 36 000 tonnes annually (Helcom, 2017). However, it must be kept in mind, that all so called internal load is actually land-based by its origin. Therefore, the priority should still be in reducing nutrient load from land, and, in addition, some complementary measures could locally be taken into use also the in sea, if found efficient and applicable.
Q What’s the use of any land-based measures, if there’s this much phosphorus already stored in the sea?
A In natural conditions, nutrients are stored in the bottom sediment, it is part of the nutrient cycles in the sea. Problems are arising, when the natural processes are interfered by external activities, e.g. excess anthropogenic nutrient loads that are causing eutrophication of the sea and, as a symptom, anoxia in the seafloor. In such conditions, the nutrients stored in the seabed are released back to the water, causing the so called “internal load”. By reducing nutrient inputs from land, the natural processes will eventually have the possibility to recover. However, it will take time, even several decades, before considerable positive trends in the environment can be seen.
Q How much phosphorus is removed from the Baltic Sea as a result of the SEABASED project?
A The first and foremost goal is to test and pilot new procedures and measures, and therefore concrete reductions are difficult to estimate before knowing the results from pilots. Although there is a possibility that reductions will remain relatively moderate within this project, the current estimate is that a reduction of approximately 5 tonnes of phosphorus could be achieved with the pilot activities. However, if proven feasible, the piloted measures could have a potential to remove several tonnes of phosphorus in future projects.
Q How can you make sure that the pilot projects do not cause permanent damage to the ecosystem?
A The possible risks are thoroughly assessed beforehand, and the pilot sites will be selected according to their environmental status: heavily eutrophied areas, with anoxic, dead bottoms where no more damage can be caused are the most suitable for project pilots. Also, the potential habitats of endangered species will be mapped beforehand, to avoid any potential damage. The pilots will be small scale and focused in closed bays, so the impacts, also positive ones, will as well remain very local.
Q Sounds like whatever is tested in the SEABASED project is only first-aid measures. Wouldn’t it be better to try to identify sustainable measures to reduce the nutrient load of the Sea?
A The John Nurminen Foundation is constantly working also on reducing nutrient load from land, with the most cost-efficient measures, as are also the countries around the Baltic Sea. The recovery of the sea is a slow process, and for example some coastal areas offering valuable ecosystem services to coastal habitats and livelihoods, could potentially benefit also from efficient first-aid measures.
Q According to the report made by Vahanen Environment, commissioned by Finnish Ministry of Environment, large-scale measures to control internal nutrient load to the Sea can cause permanent damage to the Sea.
A The focus of SEABASED Project is in local, small scale measures, and thus, no permanent damage to the sea ecosystem as a whole can be caused.