Recruitment variation can be a major source of fluctuation in populations and communities, making it difficult to generalize results. Determining the scales of variation and whether spatial patterns in the supply of individuals are persistent over time can provide insight into spatial generality and the application of conservation and metacommunity models. We examined these issues using eight‐year‐long data sets of monthly recruitment of intertidal mussels (Mytilus spp., Perumytilus purpuratus, Semimytilus algosus, Brachidontes granulata) and barnacles (Balanus glandula, Chthamalus dalli, Jehlius cirratus, Notochthamalus scabrosus) at sites spanning >900 km along the coasts of Oregon–northern California (OR–NCA, 45.47–39.43° N) and central Chile (CC, 29.5–34.65° S). We evaluated four general “null” hypotheses: that despite different phylogenies and great spatial separation of these taxa, their similar life history strategies and environmental settings lead to similar patterns of recruitment (1) between hemispheres, (2) in time, (3) in space, and (4) at larger and smaller spatial scales. Hypothesis 1 was rejected: along the OR–NCA coast, rates of recruitment were between two and three orders of magnitude higher, and patterns of seasonality were generally stronger and more coherent across space and time than along CC. Surprisingly, however, further analysis revealed regularities in both time and space for all species, supporting hypotheses 2 and 3. Temporal decorrelation scales were 1–3 months, and characteristic spatial scales of recruitment were ∼250 km. Contrary to hypothesis 4, for the ecologically dominant species in both hemispheres, recruitment was remarkably persistent at larger mesoscales (kilometers) but was highly stochastic at smaller microscales (meters). Across species, increased recruitment variation at large scales was positively associated with increased persistence. Our results have several implications. Although the two regions span distinct latitudinal ranges, potential forcing processes behind these patterns include similar large‐scale climates and topographically locked hydrographic features, such as upwelling. Further, spatial persistence of the recruitment patterns of most species at the mesoscale supports the view that marine protected areas can be powerful conservation and management tools. Finally, persistent and yet contrasting spatial patterns of recruitment among competing species suggest that recent metacommunity models might provide useful representations of the mechanisms involved in species coexistence.

Early naturalists suggested that predation intensity increases toward the tropics, affecting fundamental ecological and evolutionary processes by latitude, but empirical support is still limited. Several studies have measured consumption rates across latitude at large scales, with variable results. Moreover, how predation affects prey community composition at such geographic scales remains unknown. Using standardized experiments that spanned 115° of latitude, at 36 nearshore sites along both coasts of the Americas, we found that marine predators have both higher consumption rates and consistently stronger impacts on biomass and species composition of marine invertebrate communities in warmer tropical waters, likely owing to fish predators. Our results provide robust support for a temperature-dependent gradient in interaction strength and have potential implications for how marine ecosystems will respond to ocean warming.

Investigating how food supply regulates the behavior and population structure of predators remains a central focus of population and community ecology. These responses will determine the strength of bottom‐up processes through the food web, which can potentially lead to coupled top‐down regulation of local communities. However, characterizing the bottom‐up effects of prey is difficult in the case of generalist predators and particularly with predators that have large dispersal scales, attributes that characterize most marine top predators. Here we use long‐term data on mussel, barnacle, limpet, and other adult prey abundance and recruitment at sites spread over 970 km to investigate individual‐ and population‐level responses of the keystone intertidal sunstar Heliaster helianthus on the coast of Chile. Our results show that this generalist predator responds to changes in the supply of an apparently preferred prey, the competitively dominant mussel Perumytilus purpuratus. Individual‐level parameters (diet composition, per capita prey consumption, predator size) positively responded to increased mussel abundance and recruitment, whereas population‐level parameters (density, biomass, size structure) did not respond to bottom‐up prey variation among sites separated by a few kilometers. No other intertidal prey elicited positive individual predator responses in this species, even though a large number of other prey species was always included in the diet. Moreover, examining predator–prey correlations at ∼80, 160, and 200 km did not change this pattern, suggesting that positive prey feedback could occur over even larger spatial scales or as a geographically unstructured process. Thus individual‐level responses were not transferred to population changes over the range of spatial scales examined here, highlighting the need to examine community regulation processes over multiple spatial scales.

Marine coastal habitats are being increasingly impacted by human activities. In addition, there are dramatic climatic disruptions that could generate important and irreversible shifts in coastal ecosystems. Long-term monitoring plays a fundamental and irreplaceable role to establish general baselines from which we can better address current and future impacts and distinguish between natural and anthropogenic changes and fluctuations. Here we highlight how over 25 years of monitoring the coastal marine ecosystem within the no-take marine protected area of Las Cruces has provided critical information to understand ecological baselines and build the necessary ecological literacy for marine management and conservation. We argue that this understanding can only be gained with simultaneous monitoring of reserves and human-impacted areas, and the development of complementary experimental studies that test alternative hypothesis about driving processes and mechanisms. In this contribution we selected four examples to illustrate long-term temporal fluctuations at all trophic levels including taxa from algae to sea birds. From these examples we draw a few general lessons: a) there is co-occurrence of rapid- and slowly- unfolding ecological responses to the exclusion of humans within the same rocky shore community. The sharp differences in the pace at which depleted populations recover is at least partly related to differences in life history (dispersal capabilities) of the targeted species. b) Long-term monitoring of the supply-side of marine communities is critical to evaluate the potential feedback effects of local changes in abundance into the arrival of new individuals and to correctly evaluate environmental and human-induced perturbations. c) Unexpected changes in local population dynamics can occur in “independent” and apparently non-interactive modules of the marine ecosystem, such as roosting sea birds inside the reserve. In addition we discuss the way in which ecological data generated from long-term monitoring at marine reserves was institutionalized in a national marine management policy. At the same time, we highlight the mismatch between the gained scientific information and principles from these studies and the current concept of marine protected areas that is being implemented by some government agencies in Chile. Information from long term monitoring programs has proved essential to understand how marine environments respond to anthropogenic and/or natural disturbances, however funding these schemes, which generally have no short term gains for funding agencies in both developing and developed countries, still remain a major challenge.