Impact of altitude on spring macroinvertebrates and water quality in South West region of Cameroon

Abstract

We evaluated the impact of altitude on the biodiversity and water quality of 13 springs located from 82 to 1,189-m a.s.l. on Mount Cameroon. The springs were of good chemical and ecological quality whatever the altitude. The analysis of the physicochemical variables showed low temperature levels (19.50-±-2.09 C), high turbidity (13.0-±-7.17 FTU), and an acceptable mineralization level (324.95-±-260.0-μS/cm), with high amounts of phosphate nutrients (0.83-±-0.47-mg/L). We observed a strong seasonal effect, with a decrease in temperature and nutrient content during the dry season whereas pH and dissolved oxygen increased. A total of 10,265 organisms, distributed into 56 families, were collected. They mostly included insects (47.8%), closely followed by Arachnida (34.8%). Only two stygobite taxa were recorded, namely Darwinulidae and Stenasellidae. Total diversity slightly decreased with altitude, especially during the dry season. Despite lower temperature and more oxygen at higher altitudes, diversity, including EPT did not increase. Therefore, African fauna are less sensitive to rising temperature than the faunas of other areas of the world. This result may be explained either by the fact that African species are better adapted to warm, low-oxygen waters than species from other parts of the world, or by the absence of refuges in Mount Cameroon that are home to temperature-sensitive species. Consequently, the impact of climate change on aquatic macroinvertebrates in tropical Africa could be reduced.