Tourism and urban development as drivers for invertebrate diversity loss on tropical islands

Oceanic islands harbour a disproportionately high number of endemic and
threatened species. Rapidly growing human populations and tourism are
posing an increasing threat to island biota, yet the ecological
consequences of these human land uses on small oceanic island systems have
not been quantified. Here, we investigated and compared the impact of
tourism and urban island development on ground-associated invertebrate
biodiversity and habitat composition on oceanic islands. To disentangle
tourism and urban land uses, we investigated Indo-Pacific atoll islands,
which either exhibit only tourism or urban development, or remain
uninhabited. Within the investigated system, we show that species
richness, abundance, and Shannon diversity of the ground-associated
invertebrate community are significantly decreased on islands used for
tourism and on islands with urban development, relative to uninhabited
islands. Remote-sensing-based spatial data suggests that habitat
fragmentation and a reduction in vegetation density are having significant
effects on biodiversity on urban islands, whereas land use/ cover changes
could not be linked to the documented biodiversity loss on tourist
islands. This offers first direct evidence for a major terrestrial
invertebrate loss on remote oceanic islands due to different human land
uses with yet unforeseeable long-term consequences for the stability and
resilience of oceanic island ecosystems.