Abstract

This work presents the outcomes from five semi-quantitative loop models of different levels of complexity, built to explore and quantify the stability and resilience (used as proxies for sustainability) of the ecological and eco-social systems where intensive artisanal fishing activity of the algae Durvillaea incurvata (Di) and Lessonia spicata (Ls) is occurring in central Chile (Maule Region). The average values for Routh-Hurwitz local stability criterion 1 (Fs) and for Levins' criterion (Fn) showed that the model systems achieved the desired stability and resilience only when both algae exhibit asymmetric level of abundance (avoiding symmetric competition). Furthermore, both species should exhibit self-negative feedback, that is, their abundances should fluctuate between k/2 and maximum abundance (according to logistic growth). The latter results imply that both algae were the most sensitive to perturbations, regardless of their level of complexity, which limits exploitation strategies and emphasizes the need for integrated management. The substrate (S) also emerged as sensitive in the system. When fishers (F) and demand (D) are dominated by self-negative feedback, the average values of local stability (Fs) and resilience (Fn) were higher than when F and D exhibited self-positive feedback. Therefore, to ensure a sustainable exploitation of both algae, it would be necessary to: maintain the asymmetry of abundance (regardless of which of the two dominates), monitor the quality of the coastal rocky substrate to ensure the colonization of new plants, particularly L. spicata and D. incurvata, and design and implement policies that promote control over the activity of fishers and demand.