Ecological networks are theoretical abstractions that represent ecological communities. These networks are usually defined as static entities, in which the occurrence of a particular interaction between species is considered fixed despite the intrinsic dynamics of ecological systems. Trophic interactions, in particular, are often temporally dynamic in nature, ranging from so-called first-order dynamics to cyclical. However, empirical analysis of the temporal variation of trophic interactions is constrained by the lack of data with high spatial, temporal, and taxonomic resolution. Here, we evaluate the spatiotemporal variability of multiple consumer-resource interactions of large marine intertidal rockyshore networks. In order to generate the networks, more than 1,000 km of the coast of northern Chile was monitored seasonally over 3 years. The trophic interactions of all of the analyzed networks had low temporal persistence, which was well described by a common exponential decay in the rankfrequency relationship of consumer-resource interactions. This common pattern of low temporal persistence was evident despite the dissimilarities of environmental conditions among sites. Betweensite rank correlations of frequency of occurrence of interactions ranged from 0.59 to 0.73. After removing the interactions with <50% frequency, the between-site correlations decreased to values between 0.60 and 0.28, indicating that low-frequency interactions accounted for the apparent similarities between sites. Our results demonstrate, therefore, that the communities studied were characterized by few persistent interactions and a large number of transient trophic interactions. We suggest that consumer-resource temporal asynchrony in addition to varying local environmental conditions and opportunistic foraging could be among the mechanisms generating the observed rankfrequency relationship of trophic interactions. Therefore, our results question the analysis of ecological communities as static and persistent natural entities and stress the need for strengthening the analysis of temporal variability in ecological networks and long-term studies.

The ecological consequences of human‐driven overexploitation and loss of keystone consumers are still unclear. In intertidal rocky shores over the world, the decrease of keystone macrograzers has resulted in an increase in the dominance of herbivores with smaller body (i.e., “mesograzers”), which could potentially alter community assembly and structure. Here, we experimentally tested whether mesograzers affect the structure of rocky intertidal communities during the period of early colonization after the occurrence of a disturbance. A manipulative field experiment was conducted to exclude mesograzers (i.e., juvenile chitons, small snails, amphipods, and juvenile limpets) from experimental areas in an ecosystem characterized by the overexploitation of keystone macrograzers and predators. The results of multivariate analyses suggest that mesograzers had significant effects on intertidal community structure through negative and positive effects on species abundances. Mesograzers had negative effects on filamentous algae, but positive effects on opportunistic foliose algae and barnacles. Probably, mesograzers indirectly favored the colonization of barnacles and foliose algae by removing preemptive competitors, as previously shown for other meso‐ and macrograzer species. These results strongly support the idea that small herbivores exert a firm controlling effect on the assembly process of natural communities. Therefore, changes in functional roles of top‐down controllers might have significant implications for the structure of intertidal communities.

Improving our understanding of stability across spatial scales is crucial in the current scenario of biodiversity loss. Still, most empirical studies of stability target small scales. We experimentally removed the local space‐dominant species (macroalgae, barnacles, or mussels) at eight sites spanning more than 1000 km of coastline in north‐ and south‐central Chile, and quantified the relationship between area (the number of aggregated sites) and stability in aggregate community variables (total cover) and taxonomic composition. Resistance, recovery, and invariability increased nonlinearly with area in both functional and compositional domains. Yet, the functioning of larger areas achieved a better, albeit still incomplete, recovery than composition. Compared with controls, smaller disturbed areas tended to overcompensate in terms of total cover. These effects were related to enhanced available space for recruitment (resulting from the removal of the dominant species), and to increasing beta diversity and decaying community‐level spatial synchrony (resulting from increasing area). This study provides experimental evidence for the pivotal role of spatial scale in the ability of ecosystems to resist and recover from chronic disturbances. This knowledge can inform further ecosystem restoration and conservation policies.

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