Positive feedbacks in seagrass ecosystems: Implications for success in conservation and restoration

Seagrasses are threatened by human activity in many locations around the world. Their decline is often characterized by sudden ecosystem collapse from a vegetated to a bare state. In the 1930s, such a dramatic event happened in the Dutch Wadden Sea. Before the shift, large seagrass beds (Zostera marina) were present in this area. After the con-struction of a large dam and an incidence of the ‘‘wasting disease‘ ‘ in the early 1930s, these mead-ows became virtually extinct and never recovered despite restoration attempts. We investigated whether this shift could be explained as a critical transition between alternative stable states, and whether the lack of recovery could be due to th