Network analysis challenges the functional importance of charismatic and commercial species in the Gulf of California food web

Abstract

Ecosystem-based management for marine life conservation is of growing consensus, although the focus on protecting either charismatic or commercially important species still persist, understating species playing key functional roles. Here we quantified the topological importance of species with high economic or conservation value by simulating extinction scenarios in the Gulf of California trophic network. We found food web robustness against removals of charismatic or commercially important species. Instead, other species suggest strong roles on food web functioning. Invertebrates such as squids and crustaceans are in crucial intermediate positions, making them key bottlenecks for energy transfers. A mixed ecosystem control is at play in the food web, which is dominated by species controlling the indirect effects in top-down forcing as white sharks and hammerheads and bottom-up forcing imposed by the phytoplankton. Direct effect transmission is regulated by the silky shark due to its diverse diet. Only two charismatic removals, blue whale and white shark affected the closeness centrality patterns, whereas only blue shrimp and Monterrey sardine are commercially important species with functional relevance roles in the food web. We hope our network analysis will help decision makers in the development of novel conservation policies. Our results highlight in fact the importance of loliginid squid and blue shrimp populations, having beneficial indirect effects for the protection of charismatic species. This study is particularly timing since islands and protected areas of the Gulf of California were upgraded to the highest level of concern by the UNESCO World Heritage Convention in 2020.