Short term response of dung beetle communities to disturbance by road construction in the Ecuadorian Amazon

In the tropics, human disturbance continuously challenges initiatives for habitat conservation. In these regions, as economical budgets for conservation shrink, conservation planning requires precise information on when and how different kinds of disturbance may affect natural populations, but also on adequate experimental designs to monitor them. Due to their high diversity, ecological role, stable taxonomy and facilities to sample, dung beetles are used in biodiversity surveys for conservation purposes worldwide. Here we studied the short-term effects of dung beetle communities to an important and widespread ecological disturbance due to road construction in the Amazon basin. We surveyed the dung-beetle community in a spatio-temporal context, i.e. in transects located at 10, 50 and 100-m from a newly constructed, 10-m wide, paved road. The sampling periods took place 1, 3 and 6 months after the construction. During the survey, we collected 4895 specimens that belong to 69 species in 19 dung beetles genera. Six dung beetles species (Canthon aequinoctialis, C. luteicolis, Dichotomius fortestriatus, Eurysternus caribaeus, E. con fusus and Onthophagus haematopus) accounted for 55% of all individuals collected. Both species diversity and abundance tended to decrease during the 6 months after the opening of the road, but not with distance from the road. Accordingly, an NMDS analysis revealed clear differences in dung beetle community composition and biomass among the three sampling periods, but not with respect to transect location. However, the number of rare species tended to increase toward the forest interior. A detailed analysis of dung beetle species among transects revealed that 5 species (Sylvicanthon bridarollii Canthidium sp. 2, C. sp. 6, C. sp. 7 and Ontherus diabolicus) were more abundant when getting further from the road. On the contrary 6 species (Eurysternus hamaticollis, E. velutinus, E. con fusus, E. caribaeus, Deltochilum oberbengeri and D. orbiculare) increased in abundance in the transect next to the road. Our study therefore confirmed that while overall community metrics did not respond to road construction, several rare dung beetle species did, within an incredibly rapid time frame. While pattern based descriptions of dung beetle responses to anthropogenic activities are common in the literature, our findings suggest that effect of roads is certainly under emphasized.