Cost Effectiveness of Ecosystem-Based Nutrient Targets—Findings from a Numerical Model for the Baltic Sea

Ing-Marie Gren,Wondmagegn Tirkaso

doi:10.3390/w12102679

Abstract

An ecosystem-based management of a large sea can give heterogeneous nutrient load targets for different parts of the sea. Cost effective solutions to heterogeneous nutrient reductions targets based on ecological conditions are compared with the same overall nutrient reductions to the Baltic Sea. To this end, a numerical programming model is used, which includes eight different nutrient abatement measures (fertilizer and livestock reduction, cultivation of catch crops, reduced airborne nitrogen emissions, improved cleaning at sewage treatment plants, construction of wetlands and buffer strips, and mussel farming) in 21 catchments of the Baltic Sea. The results indicate that the cost for the international agreement on maximum load targets to different marine basins amounts to 5.3 billion euro. This is more than twice as large as the cost for the same total nutrient load targets to the Baltic Sea without specific targets for the marine basins. However, the resulting nutrient loads to the different marine basins deviate from the basin targets where the loads are lower for some basins but can exceed that for one basin, Baltic Proper, by approximately 22 per cent. Whether or not the ecological costs and benefits from deviations in basin targets under the Baltic Sea targets exceed the excess abatement cost of 2.9 billion euro for achieving the marine basin targets remains to be verified.

Highlights

The EU Marine Strategy Framework Directive envisages that the management of marine waters shall be guided by an ecosystem-based approach (EU [1])
The resulting nutrient loads to the different marine basins deviate from the basin targets where the loads are lower for some basins but can exceed that for one basin, Baltic Proper, by approximately 22 per cent
The main purpose of this study was to calculate costs of achieving overall and ecosystem-based heterogeneous targets for nutrient loads to the Baltic Sea, and to compare the dispersal of nutrient loads. This was made with a static cost minimization model, which included eight different abatement measures in each of the 21 catchments

Summary

Introduction

The EU Marine Strategy Framework Directive envisages that the management of marine waters shall be guided by an ecosystem-based approach (EU [1]). The management can be focused on marine regions or subregions, such as different marine basins in a sea. This could imply different nutrient targets within a sea, which is the case for nutrient load targets for the Baltic Sea [2]. Movements of nutrients in the sea makes it difficult to target nutrient reductions from land to specific marine basins (e.g., [3]). It is well-known in economics that detailed targets at the spatial scale imply high costs for reaching a given overall pollutant reduction target (e.g., [4]). Despite the large literature on cost effective nutrient reductions (e.g., [5,6,7]), there is no study comparing costs and spatial outcomes between overall and ecosystem-based targets

Objectives

Findings

Discussion

Conclusion