The value of novel ecosystems: Disclosing the ecological quality of quarry lakes.

Intense sand and gravel mining has created numerous man-made lakes around the world in the past century. These small quarry lakes (1-50 ha) are usually hydrologically isolated, often deep (6-40 m) and stratify during summer and in cold winters. Due to their small size, these deep man-made lakes are usually not included in the regular monitoring campaigns, e.