La Llegada de la Crisis

Based on this evaluation of the physical setting, nutrient sources and trends, ecosystem responses, experience related to reversing eutrophication and the Swedish strategy, the Panel draws the following findings and recommendations:

1) Sweden’s progress in assessing and combating the deleterious over- enrichment of the seas along its West Coast is commendable from both an international and a regional perspective. However, despite the fact that nutrient loadings and environmental concentrations have been reduced, the ecosystems have yet seen little improvement and in some cases, for example the proliferation of filamentous algae, seem to be undergoing progressive decline. While some of this recalcitrance is related to the time lags for ecosystem recovery, greater reductions of human nutrient inputs will be required in order to meet the Zero Eutrophication objective.

a. Because substantial reductions in nutrient loading from point sources have already been achieved and the opportunity for further

reductions from these sources are limited, reductions in diffuse- source and atmospheric emissions from Sweden will be required. b. Reducing Swedish nutrient emissions alone will be insufficient to

achieve the Zero Eutrophication objective because a large share of the human nutrient inputs emanates from Denmark or are brought into the West Coast seas by flows from the Baltic and North seas and by atmospheric transport. Parallel efforts to reduce nutrient

emissions from Baltic and North Sea nations will be required. 2) There is compelling evidence that both nitrogen and phosphorus are important contributors to over-enrichment of the West Coast seas and management strategies should address both nutrients. In contrast to the Baltic Sea, where there remains some scientific disagreement about the efficacy of reducing nitrogen because of the prevalence of seasonal N2

fixation by cyanobacteria, there is abundant evidence and no significant disagreement that reductions of nitrogen loads are essential for reversing regional eutrophication. Further reductions in phosphorus loadings are likely to produce mostly localized benefits.

3) There are indications that the ecosystem is beginning to respond to nutrient controls, as evidenced in measured declines in point and diffuse source emissions, atmospheric deposition, environmental nutrient concentrations and phytoplankton biomass and production. However, it is difficult to predict to what degree and how rapidly ecosystem recovery will proceed.

a. Achievement of environmental objective of Zero Eutrophication will be slow and be manifest by gains and setbacks. Complete recovery of some pre-existing conditions, such as bottom oxygen levels, may not be possible.

b. Progress is delayed because nutrients are retained and recycled in ecosystem and biological processes (e.g. abundant filamentous algae and the paucity of deeply burrowing benthos) create positive

feedbacks that make the ecosystem resistant to recovery.

c. Kattegat hypoxia, recovery of coastal vegetation (Zostera and algal mats) and benthic animal communities should be considered key ecological indicators of ecosystem recovery.

4) Other ecosystem interactions also affect recovery, including fishery declines and associated top-down controls. In addition, climate change effects may make achievement of objective more difficult by increasing runoff and stratification, warming temperatures (affecting algal growth and composition), and altering boundary conditions with the North and Baltic seas. These will require periodically redefining achievable endpoints for ecosystem recovery.

5) Better coordination of monitoring, research and assessment is required in order to pursue the Zero Eutrophication objective through adaptive management. Elements include:

a. Improved effectiveness and efficiency of local, subregional (counties), national and international monitoring to assess key indicators of pressures and responses.

b. Greater attention to quality assurance and standardization of techniques, particularly for biological measurements (e.g. benthic vegetation), and to the development of “leading indicators” of ecosystem recovery.

c. An appropriate balance in monitoring efforts devoted to achieving balance between national strategy and EU-directives.

d. Better integration of modeling, monitoring and research, including facilitating the use of monitoring results in research, supporting research on critical processes to help interpret monitoring, and integrated assessments using both models and monitoring results. More effective collaboration among SEPA, SMHI and universities in research, modeling, monitoring and assessment. The newly

established “marine research institute” at the University of Göteborg holds promise in this regard.

e. Contextual relationships with broader ecosystem-based management efforts, particularly related to fisheries and agricultural landscapes. 6) Research and syntheses of knowledge on the causes and consequences of

eutrophication of West Coast seas have provided an adequate basis for determining the requirements for reversing eutrophication and the benefits of achieving the Zero Eutrophication objective. In many ways this science has led the world related to understanding coastal eutrophication. While there is a solid basis on which to act, strategic research designed to narrow

key uncertainties would be helpful and should be pursued. Among those critical questions which require more research for better understanding and quantification are the following:

a. The recycling of nitrogen and phosphorus, particularly the sediment- water column coupling, and the biogeochemical processes that regulate recycling. These affect nutrient limitation of phytoplankton production, rates of nutrient removal from the ecosystem

(particularly with regard to denitrification), release of internally stored loads, positive feedbacks and associated thresholds that limit the extent and rate of ecosystem recovery.

b. The role of the Jutland Coastal Current in supplying nutrients to the West Coast seas. This requires further resolution, because of conflicting views in the literature, in order to determine the load reductions from North Sea-draining rivers required to achieve the Zero Eutrophication objective.