Résumé
High species richness is thought to support the delivery of multiple
ecosystem functions and services under changing environments. Yet, some
species might perform unique functional roles while others are redundant.
Thus, the benefits of high species richness in maintaining ecosystem
functioning are uncertain if functions have little redundancy, potentially
leading to high vulnerability of functions. We studied the natural
propensity of assemblages to be functionally buffered against loss prior
to fishing activities, using functional trait combinations, in coral reef
fish assemblages across unfished wilderness areas of the Indo-Pacific:
Chagos Archipelago, New Caledonia and French Polynesia. Fish functional
diversity in these wilderness areas is highly vulnerable to fishing,
explained by species- and abundance-based redundancy packed into a small
combination of traits, leaving most other trait combinations (60%)
sensitive to fishing, with no redundancy. Functional vulnerability peaks
for mobile and sedentary top predators, and large species in general.
Functional vulnerability decreases for certain functional entities in New
Caledonia, where overall functional redundancy was higher. Uncovering
these baseline patterns of functional vulnerability can offer early
warning signals of the damaging effects from fishing, and may serve as
baselines to guide precautionary and even proactive conservation actions.