Value of artificial ponds for aquatic beetle and bug conservation in the Cape Floristic Region biodiversity hotspot

摘要

1. Freshwater insect species and their host ecosystems are widely threatened. This is particularly so within the agricultural and urban landscapes of Mediterranean-type ecosystems, including those of the Cape Floristic Region (CFR), South Africa. The value of 18 artificial ponds in the CFR was determined for aquatic beetle and bug abundance and species richness, a topic that has been little explored in Africa in general. 2. In total, 17 814 aquatic beetle and bug individuals were sampled, from 94 taxa, representing 37 genera and 57 species. Bugs were much more abundant than beetles, representing 82% of all the individuals collected. The beetle and bug fauna showed high levels of endemism, with 36% restricted to the Western Cape Province. 3. Five distinct groupings based on species abundances were identified, revealing overall high dissimilarities between groups, ranging from 65% to 82%. 4. The associated physico-chemical characteristics of these sites were also investigated. The most important characteristics structuring pond communities were elevation, temperature, pH, pond size and flow regime. For bugs alone, the same variables, except elevation, were important. For beetles, only three variables were found to be most important in explaining community structure: elevation, pH, and flow regime. 5. Artificial ponds in the CFR increase the area of occupancy of these insects, and therefore play a major role in conserving them