Top-down and bottom-up forces determine ecosystem function and dynamics. Fisheries as a top-down force can shorten and destabilize food webs, while effects driven by climate change can alter the bottom-up forces of primary productivity. We assessed the response of a highly-resolved intertidal food web to these two global change drivers, using network analysis and bioenergetic modelling. We quantified the relative importance of artisanal fisheries as another predator species, and evaluated the independent and combined effects of fisheries and changes in plankton productivity on food web dynamics. The food web was robust to the loss of all harvested species but sensitive to the decline in plankton productivity. Interestingly, fisheries dampened the negative impacts of decreasing plankton productivity on non-harvested species by reducing the predation pressure of harvested consumers on non-harvested resources, and reducing the interspecific competition between harvested and non-harvested basal species. In contrast, the decline in plankton productivity increased the sensitivity of harvested species to fishing by reducing the total productivity of the food web. Our results show that strategies for new scenarios caused by climate change are needed to protect marine ecosystems and the wellbeing of local communities dependent on their resources.

Resumen.-En los últimos 50 años, el rol trófico de los consumidores se convirtió en un tópico importante en la ecología de costas rocosas de Chile, centrándose en especies de equinodermos, crustáceos y moluscos tipificadas como herbívoros y carnívoros principales del sistema intermareal. Sin embargo, la dieta y comportamiento de muchos consumidores aún no son bien conocidos, dificultando abordar problemas clave relativos por ejemplo a la importancia de la omnivoría, competencia intra-e inter-específica o especialización individual. Intentando corregir algunas deficiencias, ofrecemos a los investigadores un registro dietario exhaustivo y descriptores ecológicos relevantes para 30 especies de amplia distribución en el Pacífico sudeste, integrando muestreos estacionales entre 2004 y 2007 en 4 localidades distribuidas en 1.000 km de costa en el norte de Chile. Basados en el trabajo de terreno y laboratorio, se presenta : (a) una matriz de consumidores-recursos generada por análisis de alta resolución del contenido intestinal de 6.377 individuos, incluyendo 222 presas (80% identificadas a nivel de especie o género), (b) estimaciones de densidad, tamaño corporal (longitud y peso), amplitud dietaria (a nivel de individuo y especie), y diversidad intra-individual de los consumidores, (c) una ordenación nMDS de la similitud en composición dietaria entre consumidores, e información para cada consumidor sobre importancia relativa y frecuencia de ocurrencia de las presas más comunes. Considerando la amplia dieta omnívora y alta superposición de los consumidores, discutimos su potencial competitivo y el rol de la especialización individual en su carácter generalista, destacando la necesidad de reevaluar su comportamiento y efectos ecológicos en la comunidad intermareal.Palabras clave: Dieta, amplitud de nicho, especialización individual, omnivoría, tamaño corporal Abstract.-In the last 50 years, the trophic role of consumers has become a main research topic in the ecology of Chilean rocky shores, and in other regions. Several studies have typified species of echinoderms, crustaceans and mollusks as the most important herbivores and carnivores of intertidal assemblages. Unfortunately, little is known about the diet and behavior of many consumers, making difficult addressing key issues related to the importance of omnivory, intra-and inter-specific competition, or individual specialization. The goal of this paper is to fill some gaps in the available information and provide researchers with an exhaustive dietary analysis and relevant ecological descriptors for a suite of 30 consumer species distributed along the southeastern Pacific coast. Our data integrate information collected through seasonal samplings conducted between 2004 and 2007 at 4 localities distributed over 1,000 km of coast in northern Chile. Based on laboratory and field work analysis, we present: (a) a consumer-resource matrix obtained from high-resolution analyses of gut contents of 6,377 individuals, including 222 prey items (80% identified at species or genu...

Earth's biosphere is undergoing drastic reorganization due to the sixth mass extinction brought on by the Anthropocene. Impacts of local and regional extirpation of species have been demonstrated to propagate through the complex interaction networks they are part of, leading to secondary extinctions and exacerbating biodiversity loss. Contemporary ecological theory has developed several measures to analyse the structure and robustness of ecological networks under biodiversity loss. However, a toolbox for directly simulating and quantifying extinction cascades and creating novel interactions (i.e. rewiring) remains absent. Here, we present NetworkExtinction—a novel R package which we have developed to explore the propagation of species extinction sequences through ecological networks and quantify the effects of rewiring potential in response to primary species extinctions. With NetworkExtinction, we integrate ecological theory and computational simulations to develop functionality with which users may analyse and visualize the structure and robustness of ecological networks. The core functions introduced with NetworkExtinction focus on simulations of sequential primary extinctions and associated secondary extinctions, allowing user‐specified secondary extinction thresholds and realization of rewiring potential. With the package NetworkExtinction, users can estimate the robustness of ecological networks after performing species extinction routines based on several algorithms. Moreover, users can compare the number of simulated secondary extinctions against a null model of random extinctions. In‐built visualizations enable graphing topological indices calculated by the deletion sequence functions after each simulation step. Finally, the user can estimate the network's degree distribution by fitting different common distributions. Here, we illustrate the use of the package and its outputs by analysing a Chilean coastal marine food web. NetworkExtinction is a compact and easy‐to‐use R package with which users can quantify changes in ecological network structure in response to different patterns of species loss, thresholds and rewiring potential. Therefore, this package is particularly useful for evaluating ecosystem responses to anthropogenic and environmental perturbations that produce nonrandom and sometimes targeted, species extinctions.