The capacity of sentinel species to detect changes in environmental conditions and ecosystem structure.
Abstract
A major obstacle to preventing and reversing biodiversity loss in the Anthropocene lies in the scarcity of tools and data for monitoring the health and trajectory of ecosystems. Sentinel species can provide insight into unobserved ecosystem change, but it is unclear how effective sentinels are due to the local, context-dependent nature of past research. Here, we present the first global evaluation on the effectiveness of sentinel species as indicators of ecosystem change. We conducted a meta-analysis on 372 case studies to identify the ecological and methodological factors that correlate with the most effective sentinel species. Sentinel performance did not vary consistently across taxa or system; instead, sentinels that were more directly linked to ecosystem change due to their trophic role as predators were more effective. In addition, sentinel responses that were measured on a shorter timescale were more effective at indicating ecosystem change. Policy Implications. These results contribute to the longstanding debate on "what makes a good sentinel" and demonstrate the importance of both ecological and methodological factors when selecting sentinels to detect ecosystem change. For example, sentinel species which are trophically linked and measured on short timescales may be more effective for managers seeking to monitor ecosystem change than other species. By identifying effective traits for the use of sentinel species, scientists and policymakers will be able to develop rapid and adaptable management plans in response to global change.