Contribution of echinoderms to keystone species complexes and macroscopic properties in kelp forest ecosystems (northern Chile)

Abstract

Quantitative and semi-qualitative multispecies trophic network models were used to evaluate the importance of echinoderms to keystone species complexes (KSCs) and their contribution to macroscopic properties in kelp forest ecosystems in the northern Chilean coast. The KSC is a core of species and functional groups playing a key role in the ecosystems. The macroscopic properties quantify the ecosystem’s development, organisation and ‘health’. Dynamical simulations were used to determine the most sensitive species of echinoderms compared to the main carnivores and herbivores in the networks. The echinoderms were present in all the studied KSCs, and their contribution to macroscopic properties was low, except their influence to the ecosystem complexity in comparison to the remaining components of KSCs. The sea star Meyenaster gelatinosus and the sea urchins Tetrapygus niger and Loxechinus albus were the most sensitive species in response to an increase of their total mortality, and the ecosystems would take more time to return to initial steady-state after disturbances. The results indicated that echinoderms play a key role in the benthic ecosystems of kelp forests along northern Chile and principally contribute to the complexity and resistance against perturbations in such ecosystems.