Elevational variation of dung beetle (Coleoptera: Scarabaeidae: Scarabaeinae) communities on Bioko Island, Equatorial Guinea

Abstract

Dung beetles are important for the healthy functioning of tropical forest  ecosystems, performing essential roles, including nutrient recycling and secondary seed dispersal. Sensitive to changes in both habitat quality and vertebrate diversity, dung beetles are ideal taxa for monitoring ecosystem health. The current study provides the first documentation of dung beetle diversity on the Central African island of Bioko, Equatorial Guinea, which lies off of mainland Cameroon and is characterised by a rugged topology and an elevation of more than 3 000 m. Dung beetles were sampled from three elevations (at ~102 m, 623 m and 1 000 m) along an elevational transect, using pitfall traps baited with human dung. A total of 32 species were captured and identified. Species diversity and composition were similar to that recorded on the mainland site of Mount Cameroon, which is part of the same volcanic chain as Bioko Island. Species richness and abundance declined with increasing elevation, consistent with the inverse relationship between diversity and elevation commonly observed in other systems. Elevational preferences were apparent in several species, suggesting ecological segregation between species along the elevational gradient. The current study also provides valuable baseline data that can be used to monitor changes in ecosystem functioning and community structure, important given the potential long-term impacts of excessive bushmeat hunting on ecosystem health of Bioko Island.

Keywords: bush meat hunting, elevational gradient, diversity, species richness, west-central Africa