18 - Resilience in reef fish communities

Summary

Resilience is a utilitarian concept developed to help resource managers avoid unfavorable ecological states and maintain ecosystem functions and services when exposed to human and other disturbances. And conversely, resilience is also a conceptual approach for promoting the reversal of degraded ecological states. High biodiversity, including species, traits, and phylogenetic diversity, is predicted to increase ecological redundancy and therefore create an ecological portfolio that will increase resilience. Reef fishes have redundancy characteristics and could therefore be resilient to disturbances. Despite this potential, there is evidence for rapid and threshold-like ecological change arising from disturbances. The observed ecological change is driven less by the endogenous community organization – the usual focus of resilience theory, but more by environmental gradients or changing forces of fishing, nutrients, temperatures anomalies, and storms. Diverse life histories of reef species create the potential to reverse these ecological states through fisheries management but often slowly and only when stressors are reduced. While reef communities do shift, sometimes greatly, this high diversity can potentially resist and prevent degraded equilibrium states. Nonetheless, high biodiversity is not clearly related to high ecological services. Rather, fisheries production and reef calcification are often inversely related and frequently driven by key species or functional groups. Consequently, recognizing the key roles of species and maintaining a spatial and taxonomic portfolio that protects these roles makes good management sense. There are inherent trade-offs in ecological services, which may require promoting and managing for novel species and life-history configurations at the seascape level.

Coral reef fishes have persisted as recognizable, compared to the current species assemblages, since the Late Miocene ∼ 12 Mya [2095]. Consequently, this stasis suggests that species have evolved effectively into stable niches and assemblages that have worked out many of the conundrums of coexistence. Does this then mean that reef fishes are highly coevolved, resilient, and capable of resisting and recovering from disturbances?