Reply to Bryhn and Håkanson: Models for the Baltic agree with our experiments and observations in lakes

As Bryhn and Håkanson state (1), their mass-balance modeling yields results that agree with our observations (2) based on a long-term lake experiment and a recovery in part of the Baltic resulting from phosphorus control (3). Other recent papers (4) also support our conclusion that phosphorus control deserves a second look in coastal systems, at least those containing brackish water. As the authors (1) point out, control of nitrogen in runoff could be costly enough to cripple agriculture in some areas. We agree with them that until ecosystem-scale evidence is obtained, “N abatement is a very expensive shot in the dark that may favor cyanobacteria instead of the water quality.”