On the brink – investigating biodiversity in endangered crater lakes of the Amber Mountains National Park (Madagascar)

Abstract

ABSTRACT Madagascar's biodiversity is vanishing at an alarming pace. The documentation of this loss has so far focused on terrestrial habitats and organisms. Eight volcanic crater lakes in the Amber Mountains National Park (Northern Madagascar) and surroundings were investigated for the first time to describe limnological conditions and aquatic biodiversity. Seven of the lakes were affected by deforestation/logging and fish introduction and only one lake was assumed to have remained in pristine condition. In the deeper lakes (> 5 m) steep physico‐chemical gradients and anoxic hypolimnia were observed. Algae, hydrozoans, nematodes, rotifers, annelids, copepods, cladocerans, ostracods, and mites were identified to genus or species level. The majority were taxa with a cosmopolitan or tropicopolitan distribution. The highest number of afrotropical and endemic species were recorded within the crustaceans. Multivariate analysis of species communities revealed significant differences between lakes in deforested and forested catchments. Introduced alien fish had no detectable effect on species assemblages. Illegal harvest of timber was observed within the National Park and drug plantations are less than 1 km away from the last pristine crater lake. If deforestation continues at the current rate, which is likely under the prevailing political situation, the last undisturbed lake communities may be altered in the near future. There is an urgent need for taxonomic research to assess the biodiversity of algae and micrometazoa. Highest priority should be given to pristine freshwater ecosystems within protected areas. Copyright © 2012 John Wiley & Sons, Ltd.