Freshwater endemic species and the ecological status of streams in the Canary Islands

Abstract

An inventory has been made of endemic aquatic macroinvertebrates in streams of the Canary Islands. The inventory shows that of 31 pristine endemic species, 10 are now extinct. From the remaining 21 species, only 12 occur in streams with undisturbed hydromorphology and natural background conditions, and among these, there are 6 species that only occur in a single body of water on a single island, so they are very near to extinction. The main reason for this development is the dramatic decrease in the number of streams on the Canary Islands due to unsustainable consumption of water for agriculture and tourism and the transformation of most of the remaining streams to canals. However, natural reaches of streams with an endemic macroinvertebrate fauna still exist in specially protected areas of Tenerife, La Gomera, and La Palma. These reaches serve as reference status for the development of a specific assessment method for streams on the islands. This method takes into account common parameters such as water quality and hydromorphology, though to biodiversity and island-specific endemism is given greater emphasis. These last two concepts of stream development could be important tools in both nature conservation and protection of the remaining endemic and sensitive species.