Understory low compositional stability enhances functional stability in response to bull kelp removal in southern Chile

Abstract

Background and Aims.Ecological stability is central to understand the ability of natural systems to respond to disturbances, especially when these occur directly over important species within communities, such as foundational species. The bull kelp Durvillaea incurvata is common in intertidal and shallow subtidal rocky shores, supporting a diverse understory. The direct harvesting of Durvillaea constitute a common practice along the Chilean coast able to disrupts the abundances of the understory community and as well aggregated properties such as overall community biomass. Thus, we investigated the resistance, resilience, and recovery of the understory community of Durvillaea subjected to an experimental kelp removal in two sites from the temperate Chilean coast. Methods.We simulated a pulse removal of Durvillaea cause by direct harvesting, by removing once all the individuals within experimental plots and then we monitored the composition and biomass of the sessile and mobile understory community for 25 months. Key Results.After the disturbance we observed a rapid recovery of Durvillaea cover and varying stability responses of the understory community. Community composition showed a low resistance to the disturbance but returned rapidly within 5 - 7 months to pre disturbance levels (high resilience), however showed an incomplete recovery compared to controls. While community biomass displayed high resistance to the disturbance and then remained constant across time (resilience = 0), showing a complete recovery compared to control communities. Conclusions.Differing from Durvillaea dominated communities from other regions, our analyzed communities showed rapid recovery dynamics in compositional and functional aspects, resulting highly resilient to the type of disturbance applied. In addition, since varying stability responses reported, we encourage the use of multiple dimensions of stability to exhaustively characterize the responses of Durvillaea dominated communities and other kelps, when exposed to disturbances.