The alternative stable state concept and the management of Apennine mountain ponds

1. In mountainous areas of the central Apennines, permanent ponds and small lakes show high concentrations of nutrients causing algal blooms and fish kills. Their degraded condition is at odds with their conservation status since most of them are located within protected areas. Therefore, urgent remedial measures and management of these valuable habitats is required. 2. The concept of alternative equilibria potentially provides a scientific framework for management actions in shallow freshwater ecosystems. However, little is known regarding how this concept applies to Apennine ponds. 3. This paper examines nutrient, phytoplankton biomass, transparency and macrophyte data from 30 Apennine ponds and shallow lakes. Patterns of soluble reactive phosphorus, dissolved inorganic nitrogen, chlorophyll a and water transparency are consistent with the existence of alternative stable states. The extent of macrophyte cover plays a key role in stabilizing one of the alternative stable states. 4. Reducing nutrient inputs from the catchment, adopting measures to increase and/or restore macrophyte beds, and manipulating fish assemblages are potentially promising strategies for the restoration and conservation of Apennine ponds. Copyright © 2005 John Wiley & Sons, Ltd.