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TheScientificWorldJOURNAL - Volume 1 2001, Pages 371-377

Research Article Stockholm University, Department of Systems Ecology, Sweden



Academic Editor: Joe Wisniewski

Copyright © 2001 R. Elmgren and U. Larsson.

Abstract

The Baltic is a large, brackish sea 4 x 105 km2 extending from 54

N to ~66

N, with a fourfold larger drainage area population 8 x 107. Surface salinity 2 to 8 PSU and hence biodiversity is low. In the last century, annual nutrient loads increased to 10

metric tons N and 5 x10

ton P. Eutrophication is evident in the N-limited south, where cyanobacteria fix 2 to 4 x 10

ton N each summer, Secchi depths have been halved, and O2-deficient bottom areas have spread. Production remains low in the P-limited north. In nutrient-enriched coastal areas, phytoplankton blooms, toxic at times, and filamentous macroalgae reduce amenity values. Loads need to be reduced of both N, to reduce production, and P, to limit N-fixing cyanobacterial blooms. When large N-load reductions have been achieved locally, algal biomass has declined. So far, P loads have been reduced more than N loads. If this continues, a P-limited Baltic proper may result, very different from previous N-limited conditions. Reaching the management goal of halved anthropogenic N and P loads at minimum cost will require better understanding of biogeochemical nutrient cycles, economic evaluation of proposed measures, and improved stakeholder participation.





Autor: R. Elmgren and U. Larsson

Fuente: https://www.hindawi.com/



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