Trophic architecture as a predictor of ecosystem resilience and resistance in the eastern Pacific

Abstract

The intricate trophic structure of marine ecosystems defines their ecological properties and network metrics; it has been used extensively to assess the development and maturity of ecosystems. The Eastern Pacific is warming due to climate change, and added human stressors are affecting the trophic architecture of its marine ecosystems. We aimed to explore the maturity of ecosystems in this region under the assumption that the trophic architecture of an ecosystem is a proxy of maturity, and that there is a direct relationship between resistance and maturity and an inverse one with resilience. We applied ecosystem network analysis to model runs of published rebuilt Ecopath models to explore the potential effects of oceanographic variables and human disturbance on the trophic architecture of 13 ecosystem models, 11 models within three different Large Marine Ecosystems (LMEs) and two models describing oceanic islands, that have an array of oceanographic conditions and are subject to different human stressors. We conclude that even when ecosystem attributes cannot conclusively assert maturity stage, they can suggest how close or far the ecosystems are from maturity. We found that the ecosystems in the Gulf of California are resilient because they have a high median trophic level, high Production/Biomass ratio, and median ascendency/capacity ratio, and because they are subject to natural variations of productivity. Upwelling ecosystems are in an intermediate stage of maturity, followed by ecosystems from the Pacific Central American Coastal LME. As expected, oceanic islands, which have a production deficit, must optimize their energy transfer. Our analysis suggests that although trophic architecture cannot serve as a direct indicator of maturity, it can help estimate ecosystem resilience and identify those systems that can withstand future impacts.