Resource Pulses Research Articles

Resource pulses increase the diversity of successful competitors in a multi‐species stream fish assemblage

AbstractFood resources are often patchily distributed through space and time and are classified as resource pulses when hyperabundant. Resource pulses can benefit growth, reproduction, and abundance of various consumers. Yet, it is relatively unknown how such resources are partitioned among competing consumers and how this is influenced by the magnitude of the pulse. Here, we examined how the magnitude of a pulsed resource influences resource partitioning among diverse sizes and species of consumers in a natural setting over small spatial and temporal scales. We focused on salmon egg subsidies to stream fish consumers. We experimentally added different quantities of pink salmon eggs to five meter long experimental stream sections. Egg additions spanned three orders of magnitude from 6 to 3575 eggs. Stream fish (egg consumers) were captured and gastric lavaged at each experimental section to determine how many eggs each individual fish consumed. We modeled taxon‐specific individual egg consumption as a function of egg availability, individual mass, community composition, number of competitors, and stream velocity using hurdle models in a Bayesian framework. We found that there were diminishing returns for increasing egg abundance increasing egg consumption (i.e., type II functional response) for individual size classes of fish, but that higher egg numbers were needed to benefit diverse consumers. Top models indicated that egg availability and individual fish characteristics (size and taxon) drove egg consumption, while community characteristics (species composition and number of competitors) were not supported. Our results suggest that resource pulses can provide rare opportunities for less dominant sizes and species of fish to consume abundant resources. The current paradigm in the stream fish literature suggests that stream fish communities are structured by dominance hierarchies; however, dominance hierarchies may be less influential where pulsed resources comprise a large portion of the resource base.

Chasing the sun: When to migrate, when to breed

Chasing the sun: When to migrate, when to breed

Consumer Responses to Experimental Pulsed Subsidies in Isolated versus Connected Habitats.

AbstractIncreases in consumer abundance following a resource pulse can be driven by diet shifts, aggregation, and reproductive responses, with combined responses expected to result in faster response times and larger numerical increases. Previous work in plots on large Bahamian islands has shown that lizards (Anolis sagrei) increased in abundance following pulses of seaweed deposition, which provide additional prey (i.e., seaweed detritivores). Numerical responses were associated with rapid diet shifts and aggregation, followed by increased reproduction. These dynamics are likely different on isolated small islands, where lizards cannot readily immigrate or emigrate. To test this, we manipulated the frequency and magnitude of seaweed resource pulses on whole small islands and in plots within large islands, and we monitored lizard diet and numerical responses over 4 years. We found that seaweed addition caused persistent increases in lizard abundance on small islands regardless of pulse frequency or magnitude. Increased abundance may have occurred because the initial pulse facilitated population establishment, possibly via enhanced overwinter survival. In contrast with a previous experiment, we did not detect numerical responses in plots on large islands, despite lizards consuming more marine resources in subsidized plots. This lack of a numerical response may be due to rapid aggregation followed by disaggregation or to stronger suppression of A. sagrei by their predators on the large islands in this study. Our results highlight the importance of habitat connectivity in governing ecological responses to resource pulses and suggest that disaggregation and changes in survivorship may be underappreciated drivers of pulse-associated dynamics.

Sex- and context-specific associations between personality and a measure of fitness but no link with life history traits

The pace-of-life syndrome hypothesis posits that personality traits (i.e. consistent individual differences in behaviour) are linked to life history and fitness. Specifically, fast-paced individuals are predicted to be proactive (i.e. active and aggressive) with an earlier age at first reproduction, a shorter life span and higher fecundity than slow-paced individuals. Environmental conditions and sex differences may be important in maintaining behavioural and life history variation in populations and may influence the covariance of personality with life history or lifetime fitness. However, these effects are rarely tested together. We investigated whether the occurrence of a resource pulse (called a mast year) during adulthood altered the associations between personality and life history traits or lifetime offspring production in adult North American red squirrels, Tamiasciurus hudsonicus. Despite accounting for environmental context during adulthood, we found no evidence of an overall pace-of-life syndrome in this population as personality was not associated with age at first reproduction or longevity in either sex. Males and females had similar activity levels, but females were more aggressive, potentially due to the fitness benefits of protecting their offspring from predation. In all females, regardless of mast experience, there was no association between activity and lifetime pup production, but there was a positive association between aggression and lifetime pup production. In males that experienced a mast, there was a positive association between lifetime pup production and both activity and aggression. In males that did not experience a mast, there was no association between activity and lifetime pup production, but there was a negative association between aggression and lifetime pup production. Lifetime recruit production (number of adult offspring recruited into the breeding population) in either sex was not influenced by activity or aggression regardless of mast experience. Overall, our results suggest that the infrequent occurrence of mast years may contribute to maintaining variation in personality traits in red squirrels.

Nutrient fluctuation has different effects on a tropical invader in communities from the native and non-native range

Invader success might depend on both nutrient availability and species richness of the resident community. Here, we combine these ideas in a single experiment, testing whether the Fluctuating resource and biotic resistance hypotheses might be contingent upon one another. The fluctuating resource hypothesis proposes that resource fluctuation might facilitate the successful invasion of exotic plants if invaders are better than natives at taking advantage of resource pulses. The biotic resistance hypothesis proposed that more species rich communities might be more resistant to invasion, due to greater competition for resources with greater native richness. Here, we use an experiment with the invader, Chromolaena odorata in 315 artificial communities with resident plants from native and non-native ranges. We found that resident origin, nutrient treatment and species richness of artificial community have significant effects on invasion success of C. odorata. The effect of nutrient fluctuation on invasion success was contingent on resident origin (native vs. non-native range), and this effect was weaker in more species rich communities. In addition, the invasion success of C. odorata was negatively related with biomass of resident plants, suggesting competition as a mechanism governing invader success. Our results suggest a novel twist on the fluctuating resource hypothesis: fluctuating resources may favor invaders more in species poor communities of non-native origin. This also suggests that competition for fluctuating resources may be one mechanism governing biotic resistance because the effects of richness were greater when resources were fluctuating. Our results suggest that the fluctuating resource hypothesis will apply only to resident communities with lower resource acquisition strategies, relative to the invader.

Timing of Resource Availability Drives Divergent Social Systems and Home Range Dynamics in Ecologically Similar Tree Squirrels

Intraspecific variation in home range size has important implications for the distribution of animals across landscapes and the spatial structuring of population, community and ecosystem processes. Among species of similar trophic guild and body mass, differences in home range size can reflect extrinsic variables that exert divergent selective forces upon spacing behavior and social organization. We tested predictions about how resource availability and timing influence social system, home range size and territoriality in two tree squirrel species of similar size and ecological niches but that differ in foraging strategy and social organization. We estimated home range size and intraspecific home range core overlap in the Mt. Graham red squirrel (Tamiasciurus fremonti grahamensis; Arizona USA; MGRS) and the Eurasian red squirrel (Sciurus vulgaris; Alps, Italy; ERS) as functions of species, sex, season, and individual’s body mass. However, body mass did not explain differences found between the two species. We found MGRS home ranges being 3 times smaller with higher core area exclusivity compared to ERS in all seasons. In fact, territorial MGRS evolved in a system of brief resource pulses and are larder hoarders, whereas ERS experience prolonged resource availability and are non-territorial. Only male MGRSs increased their home range during the breeding season, reflecting interspecific differences in social organization and mating behavior. Male ERS home ranges always overlap with several females to enhance mating success, while male and female MGRS maintain nearly exclusive territories throughout the year. Only during spring and summer males temporarily leave their food-based territory to increase mating opportunities with neighboring estrus females. Home range comparisons between ecologically similar species emphasized the importance of divergent extrinsic factors in shaping variability in body size – home range size scaling relationships. Timing in resource availability influenced the social structure and space use in tree squirrels of similar body size, highlighting how the coevolution of arboreal squirrels with conifer tree species has shaped their natural history.

Good times, bad times: Resource pulses influence mammal diversity in meridional Brazilian highlands

Understanding spatiotemporal patterns of species distributions and their determinants is paramount in ecology. Here, we explore the relationship between the diversity of surviving mammals and two of the main alimentary resources (araucaria seeds and feijoa fruits) across the Araucaria Forest (FOM) in South America. First, we investigated the influence of landscape and environment on the species distribution and pulse of forest productivity. Then, we evaluated how these spatiotemporal pulses in resource availability influence the mammalian diversity. We analyzed the data via diversity descriptors, Morisita index and multiple regressions. Our findings highlighted that climate, tree density, and other environmental variables explained the pulses of productivity. Mammalian diversity of first-order consumers mammals—all those immediately feeding on seeds and fruits—was partially related to resource pulses. Our results revealed that the pulses of forest resources can influence mammal diversity over the years, including delayed responses and asynchronous oscillations. The integrity of vegetal elements of the FOM is key to maintain several mammal-mediated ecological processes. Maintaining the viability of tree populations, encouraging the sustainable use of non-timber resources, and promoting the conservation of the mammalian fauna, which is undergoing an unprecedented diversity crisis worldwide, can help to preserve the remaining ecological processes.

How does oak mast seeding affect the feeding behavior of sympatric red and roe deer?

Oak reproduction is characterized by mast seeding with high inter-annual fluctuations in fruit production. Such resource pulses can greatly affect ecosystem functioning and may cause seed consumers to alter their mobility, demography, or diet. Consequences of mast seeding for seed consumers remain poorly understood as their long timescale makes them difficult to study. We investigated impacts of oak mast seeding on the feeding behavior of two sympatric European deer species: red deer (Cervus elaphus) and roe deer (Capreolus capreolus). We analyzed their rumen content over a 31-year period in tandem with 10 years of data on oak fructification (i.e. 8 years of field monitoring and two modelled years). Acorn production is strongly correlated with consumption by both deer species. In years of high fructification, acorns represent more than 50% and 35% of red and roe deer diet, respectively, confirming assumptions that deer favor acorns when these are available. Red deer eat more acorns than roe deer both between and within years. High acorn production in mast years appears to saturate the capacity of deer to consume acorns. As the proportion of acorns increase in their diet, red deer eat more grasses and less conifer browse. No dietary shift was found for roe deer. By inducing dietary shifts in consumers, oak mast seeding can have cascading effects on ecosystem processes, notably on the damages on conifers caused by red deer and the consequences for forest dynamics.

Mast seeding patterns are asynchronous at a continental scale.

Resource pulses are rare events with a short duration and high magnitude that drive the dynamics of both plant and animal populations and communities1. Mast seeding is perhaps the most common type of resource pulse that occurs in terrestrial ecosystems2, is characterized by the synchronous and highly variable production of seed crops by a population of perennial plants3,4, is widespread both taxonomically and geographically5, and is often associated with nutrient scarcity6. The rare production of abundant seed crops (mast events) that are orders of magnitude greater than crops during low seed years leads to high reproductive success in seed consumers and has cascading impacts in ecosystems2,7. Although it has been suggested that mast seeding is potentially synchronized at continental scales8, studies are largely constrained to local areas covering tens to hundreds of kilometres. Furthermore, summer temperature, which acts as a cue for mast seeding9, shows patterns at continental scales manifested as a juxtaposition of positive and negative anomalies that have been linked to irruptive movements of boreal seed-eating birds10,11. Here, we show a breakdown in synchrony of mast seeding patterns across space, leading to asynchrony at the continental scale. In an analysis of synchrony for a transcontinental North America tree species spanning distances of greater than 5,200 km, we found that mast seeding patterns were significantly asynchronous at distances of greater than 2,000 km apart (all P < 0.05). Other studies have shown declines in synchrony across distance, but not asynchrony. Spatiotemporal variation in summer temperatures at the continental scale drives patterns of synchrony in mast seeding, and we anticipate that this affects the spatial dynamics of numerous seed-eating communities, from insects to small mammals to the large-scale migration patterns of boreal seed-eating birds.

Modelling species distributions in dynamic landscapes: The importance of the temporal dimension

AbstractAimTemporal variation in environmental conditions merits greater consideration in species distribution models (SDMs), and is especially relevant in dynamic systems, such as arid and semi‐arid environments, where precipitation and resource pulses are unpredictable in space and time. Species responses to this spatio‐temporal variation include tracking resource availability with nomadic life histories or reliance on refugia that provide stable, high‐quality habitat. This study evaluated whether inclusion of temporal variables representing short‐ and long‐term environmental variation improves SDMs.LocationGreat Western Woodlands, Western Australia.TaxonBirds.MethodsTemporal information was added to SDMs of 36 bird species with two types of environmental predictor variables: (a) time‐specific estimates of gross primary productivity (GPP) and precipitation paired to survey dates; and (b) estimates of the temporal stability of GPP over the MODIS archive, providing an index of the degree to which sites might function as habitat refugia from disturbance and drought. Predictions were compared with those from SDMs using static variables from single time points.ResultsModel predictions revealed considerable temporal variation in species distributions and various spatio‐temporal responses to environmental variation. Temporal variables modestly improved model performance overall, but results were species‐specific. Time‐specific environmental variables were most important to models of nomadic and nectivorous species, which experienced the greatest improvements in model performance when including temporal variables, and showed the greatest disagreement between temporal and static model predictions, and the predictions of temporal models applied to different time points. Long‐term environmental variation was relevant across species groups, though the chosen measure of variability differed between species.Main ConclusionsTemporal variation influences species distributions and may need to be explicitly included in SDMs. However, the nature and degree of species' responses to environmental dynamics depends on species movement behaviours; appropriate selection of temporal variables for SDMs requires ecological understanding of the species of interest. Results of spatio‐temporal SDMs can identify the extent to which landscape management must account for temporal variability to achieve conservation goals.

The necessity of tailored control of irrupting pest populations driven by pulsed resources

Resource pulses are widespread phenomena in diverse ecosystems. Irruptions of generalist consumers and corresponding generalist predators often follow such resource pulses. This can have severe implications on the ecosystem and also on the spread of diseases or on regional famines. Suitable management strategies are necessary to deal with these systems. In this study, we develop a general model to investigate optimal control for such a system and apply this to a case study from New Zealand. In particular, we consider the dynamics of beech masting (episodic synchronous seed production) leading to rodent outbreaks and subsequent stoat (Mustela erminea) irruptions. Here, stoat control happens via secondary poisoning. The results show that the main driver of the optimal control timing (June) is the population density of the control vector. Intermediate control levels are superior to higher levels if the generalist consumer is necessary as a control vector. Finally, we extend the model to a two-patch metapopulation model, which indicates that, as a consequence of the strong vector dependence, a strategy of alternating control patches yields better results than static control. This highlights that besides control level, also the design impacts the control success. The results presented in this study reveal important insights for proper pest management in the New Zealand case study. However, they also generally indicate the necessity of tailored control in such systems.

Temporal shifts in intraspecific and interspecific diet variation among 3 stream predators

Intraspecific variation is increasingly recognized as an important factor in ecological interactions that can exceed the role of interspecific variation. Few studies, however, have examined how variation in intra- and interspecific resource use affect trophic interactions over time within a seasonally-dynamic food web. We compared diets with respect to predator body size and predator species identity over 3 seasons by collecting stomach contents from 2028 Reticulate Sculpin (Cottus perplexus), 479 Coastal Cutthroat Trout (Oncorhynchus clarkii clarkii), and 107 Pacific Giant Salamanders (Dicamptodon tenebrosus) in western Oregon streams. In each season, predator body size was strongly associated with dietary composition and positively related to taxonomic breadth and the size of individual prey. Intra- and interspecific diet variation changed substantially across seasons, with much greater interspecific variation in spring than in summer and autumn. Interspecific differences in foraging mode (e.g., benthic vs drift feeding) were associated with predator-specific responses to a seasonal pulse in the availability of terrestrial thrip larvae (Thysanoptera) and contributed to temporal variation in trophic niche differentiation. These findings show that the relative magnitudes of intra- and interspecific diet differentiation can change over time in systems that receive seasonal resource pulses. Our results highlight the dynamic nature of food webs and the need to incorporate sampling over relevant temporal scales to understand species interactions.

Nine months in the Simpson Desert: The anatomy of a letter-winged kite breeding irruption

Highly mobile animals in the world's drylands can have distinct core and irruptive ranges with the latter being occupied only during population outbreaks driven by resource pulses. Breeding events occur within the irruptive range during these periods of high resource availability. Here we quantify such an event involving the letter-winged kite (Elanus scriptus) in the Simpson Desert, Australia; a region that experiences major rainfall-driven pulses in primary productivity. The irruption of kites lasted for a minimum of nine months (12 July 2016 to 24 May 2017). Breeding was confined to July–October 2016. Population size rose from an initial count of 22 adults in July to a peak of 38 adults and 19 juveniles in October 2016. The pattern of aggregation during 2016 consisted of dispersed breeding individuals whereas by 2017 this pattern was replaced by larger non-breeding aggregations. Kites arrived in the area when small mammal abundance was relatively low, but was increasing, and bred as the abundance of small mammals reached its peak. Unexpectedly, kites departed the area when abundance of small mammals was still high and sufficient to support an additional breeding event in winter-spring 2017. Our study provides insights in to the duration and size of breeding events in the irruptive range of nomadic birds. From a management perspective it identifies the importance of the keystone tree species, Acacia peuce, as a nesting site.

An unseen synchrony or recurrent resource pulse opportunity? linking fisheries with aeroecology

AbstractUnderstanding insect and fish interactions from a spatial and temporal perspective can have implications on large‐scale phenology in freshwater systems, yet current information is limited. We employed a novel approach of combining information from acoustic telemetry for six freshwater fish species and weather radar to assess the phenology of mayfly emergence and foraging patterns of freshwater fish. We hypothesized that freshwater fish conduct synchronous movements with annual mayfly hatches as a pulse resource opportunity. Generalized additive models were developed to assess movement distance as a function of species and time; before, during, and after annual mayfly hatch events. A cross‐section abundance index was also employed to quantify dynamics of aerial mayflies. Hatch dynamics revealed nocturnal emergence behaviour with annual variations in intensity, spatial extent, and origin. We found that the hatch was likely a pulse resource feeding opportunity for channel catfish, common carp, freshwater drum, and walleye instead of a synchronized feeding event. Bigmouth buffalo and lake sturgeon utilized riverine habitat away from the hatch and did not likely forage on the emerging mayflies. Remote sensing of fishes and emergent insects using our approach is the first attempt at bridging the capabilities of fisheries ecology and aeroecology to advance movement ecology.

Microbiome Dynamics Associated With the Atacama Flowering Desert.

In a desert, plants as holobionts quickly respond to resource pulses like precipitation. However, little is known on how environment and plants modulate the rhizosphere-associated microbiome. As a model species to represent the Atacama Desert bloom, Cistanthe longiscapa (Montiaceae family) was selected to study the influence of abiotic and biotic environment on the diversity and structure of the microbiota associated to its rhizosphere. We analyzed the rhizosphere and soil microbiome along a North-South precipitation gradient and between a dry and rainy year by using Illumina high−throughput sequencing of 16S rRNA gene fragments and ITS2 regions for prokaryotes and fungi, respectively. In the rhizosphere of C. longiscapa the microbiota clearly differs in composition and structure from the surrounding bulk soil. The fungal and bacterial communities respond differently to environmental conditions. The diversity and richness of fungal OTUs were negatively correlated with aridity, as predicted. The community structure was predominantly influenced by other soil characteristics (pH, organic matter content) but not by aridity. In contrast, diversity, composition, and structure of the bacterial community were not influenced by aridity or any other evaluated soil parameter. These findings coincide with the identification of mainly site-specific microbial communities, not shared along the sites. These local communities contain a group of OTUs, which are exclusive to the rhizosphere of each site and presumably vertically inherited as seed endophytes. Their ecological functions and dispersal mechanisms remain unclear. The analysis of co-occurrence patterns highlights the strong effect of the desert habitat over the soil- and rhizosphere-microbiome. The site-independent enrichment of only a small bacterial cluster consistently associated with the rhizosphere of C. longiscapa further supports this conclusion. In a rainy year, the rhizosphere microbiota significantly differed from bulk and bare soil, whereas in a dry year, the community structure of the former rhizosphere approximates to the one found in the bulk. In the context of plant–microbe interactions in desert environments, our study contributes new insights into the importance of aridity in microbial community structure and composition, discovering the influence of other soil parameters in this complex dynamic network, which needs further to be investigated.

Systematic prey preference by introduced mice exhausts the ecosystem on Antipodes Island

House mice (Mus musculus) are a widespread invasive species on islands. Where they are the sole introduced mammal they can have particularly strong negative impacts on recipient ecosystems. House mice impacts have been documented on almost every component of the terrestrial ecosystem on Southern Ocean islands, including plants, invertebrates, birds and ecosystem function. We undertook a comprehensive study to determine the impacts of house mice on Antipodes Island, New Zealand. This study was done prior to mouse eradication to inform monitoring and restoration. We used invertebrate pitfall trapping on the main Antipodes Island and neighbouring mouse-free offshore islands together with mouse stomach contents and stable isotope analyses of mouse livers to examine dietary preferences. We identified directly impacted and consumed invertebrate Orders relative to their abundance and provided a comprehensive picture of resource flow and overlap in the invaded terrestrial ecosystem. The remote terrestrial ecosystem of Antipodes Island was tightly circumscribed with strong resource overlap. Mouse diet varied seasonally with resource availability, dominated by invertebrates and land birds in summer, and plants and seabirds in winter. Invertebrates that were preferentially preyed upon were Amphipoda, Lepidoptera and some species of Coleoptera. These patterns suggest the ecosystem is annually driven by a seasonal bottom-up resource pulse over summer, where mice are a selective predator, differentially preying on invertebrates relative to invertebrate abundance. Mice appear to be exhausting preferred prey as they systematically consume their way through the terrestrial ecosystem. Land bird diet also varied seasonally and some of these birds likely competed with mice for invertebrate prey. Eradication of mice from Antipodes Island should reduce the predation on invertebrates and reduce the effects of competition and predation on land birds. This should have flow-on effects to the abundance of invertebrates and endemic land bird sub-species of pipit and snipe.

The effect of resource pulses on the competitiveness of a tropical invader depends on identity of resident species and resource type

Different species have differential physiological requirements and ecological strategies, and the resident species and resource type may affect invasiveness of alien plants. Resource pulse is an important factor influencing the invasion status of alien plants. Here, we tested the effects of irradiance and nutrient pulse on the competitiveness of the invasive plant Chromolaena odorata when cultured with two resident plants, Abelmoschus manihot and Xanthium sibiricum. Our results suggest that the response of competitiveness to a resource pulse (nutrient and irradiance) depended on species identity – Chromolaena odorata was more competitive with Abelmoschus manihot than with Xanthium sibiricum under resource pulse. Moreover, Chromolaena odorata has higher advantage than resident species in competitive conditions but not in monoculture conditions. This study provided information for controlling the future spread of invasive C. odorata.

Metaecosystem dynamics drive community composition in experimental, multi‐layered spatial networks

Cross‐ecosystem subsidies are studied with a focus on resource exchange at local ecosystem boundaries. This perspective ignores regional dynamics that can emerge via constraints imposed by the landscape, potentially leading to spatially‐dependent effects of subsidies and spatial feedbacks. Using miniaturized landscape analogues of river dendritic and terrestrial lattice spatial networks, we manipulated and studied resource exchange between the two whole networks. We found community composition in dendritic networks depended on the resource pulse from the lattice network, with the strength of this effect declining in larger downstream patches. In turn, this spatially‐dependent effect imposed constraints on the lattice network with populations in that network reaching higher densities when connected to more central patches in the dendritic network. Consequently, localized cross‐ecosystem fluxes, and their respective effects on recipient ecosystems, must be studied in a perspective taking into account the explicit spatial configuration of the landscape.

Tracking the resource pulse: Movement responses of fish to dynamic floodplain habitat in a tropical river.

Natural river floodplains are among the Earth's most biologically diverse and productive ecosystems but face a range of critical threats due to human disturbance. Understanding the ecological processes that support biodiversity and productivity in floodplain rivers is essential for their future protection and rehabilitation. Fish assemblage structure on tropical river floodplains is widely considered to be driven by dispersal limitation during the wet season and by environmental filtering and interspecific interactions during the dry season. However, the individual-level movement behaviours (e.g. site attachment, nomadism, homing) that regulate dispersal of fish on floodplains are poorly understood. We combined radiotelemetry and remote sensing to examine the movement behaviour of two large-bodied fishes (barramundi Lates calcarifer, forktail catfish Neoarius leptaspis) over the flood cycle in a tropical river-floodplain system in northern Australia to: (a) quantify movement responses in relation to dynamic habitat resources at a landscape scale; and (b) determine the extent of spatial 'reshuffling' of individual fish following the wet season. Both species altered their behaviour rapidly in response to changes in the availability and distribution of aquatic habitat, with most individuals undertaking extensive movements (up to ~27km from the tagging location) on the inundated floodplain during the wet season. Although there was considerable individual variation in movement patterns, overall barramundi distributions closely tracked the extent of floodplain primary productivity, whereas catfish distributions were most closely associated with the extent of flooded area. Most individuals of both species exhibited homing back to previously occupied dry season refugia during the wet-to-dry transition, even though other potential refugia were available in closer proximity to wet season activity areas. We postulate that homing behaviour modulates temporal variation in fish assemblage composition and abundance and limits the transfer of aquatic-derived energy and nutrients into terrestrial food webs by reducing fish mortality on drying floodplains. Our study demonstrates the importance of quantifying individual-level behaviour across the three stages of dispersal (emigration, inter-patch movement, immigration) for our understanding of how animal movement influences energetic subsidies and other large-scale ecosystem processes.

The consequences of mass mortality events for the structure and dynamics of biological communities

Mass mortality events (MMEs) are rapidly occurring, substantial population losses that transpire within a short time interval relative to the generation time of the affected organism. Previous work has established that MMEs appear to be increasing in frequency and magnitude; however, currently, there is little understanding of the consequences of MMEs for biological communities. Here, we use theory and empirical data from observed MMEs to understand how MMEs impact the structure and dynamics of communities. To do so, we build upon existing resource pulse and trophic cascade theory to show that MMEs both share similarities and diverge from these ecological phenomena, producing distinct short‐ and long‐term impacts by jointly altering the effects of species interactions across trophic levels and providing an influx of resources from decaying biomass. Second, we investigate how the magnitude of MMEs, trophic level of the impacted species, overall food web structure and ecosystem type may mediate the resulting ecological response. Third, we compare the understanding gained by our models to existing observational data on MMEs. Our synthesis, offers an empirical path forward for understanding MMEs through experimentation and improved observational data collection. While complex, resolving the consequences of MMEs should be a high research priority due to their role in determining how ecological systems respond to environmental change driven by rare events.