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Between global climate change and anthropogenic water needs, freshwater systems are becoming more intermittent, stressing organisms adapted to perennial waters. Drought‐induced intermittency concentrates aquatic organisms into drying pools. These pools represent refugia from desiccation but apply other stressors, such as extreme temperatures and increased competition for dwindling resources. In the Southern United States, fishes and freshwater mussels are often concentrated together in drying pools during seasonal, summer droughts. This can result in increased competition for food among invertivorous fish, but also increased food abundance for these fish because mussels increase macroinvertebrate abundance. Further, since mussels require fish as hosts for their ectoparasitic larval phase, glochidia, competition with their host during this biologically active time is detrimental to mussels. We conducted an experiment to examine the effects of freshwater mussels on trophic resources and fish survival in drying pools. We stocked mesocosms with juvenile largemouth bass that were infected or uninfected with glochidia and tracked abiotic conditions, trophic resources and fish survival for 10 days. We found that fish survived longer in the presence of adult mussels, regardless of their infection status. We suspect that prey items supplemented by adult freshwater mussels increased the survival of fish. Thus, the presence of adult mussels and the resources that increase in their presence potentially mitigate stress to fish in "ecological crunch times." By conserving mussels, fish populations might withstand droughts more easily. [ABSTRACT FROM AUTHOR]

Foliar nyctinasty is a plant behaviour characterised by a pronounced daily oscillation in leaf orientation. During the day, the blades of nyctinastic plant leaves (or leaflets) assume a more or less horizontal position that optimises their ability to capture sunlight for photosynthesis. At night, the positions that the leaf blades assume, regardless of whether they arise by rising, falling or twisting, are essentially vertical. Among the ideas put forth to explain the raison d'être of foliar nyctinasty are that it: (i) improves the temperature relations of plants; (ii) helps remove surface water from foliage; (iii) prevents the disruption of photoperiodism by moonlight; and (iv) directly discourages insect herbivory. After discussing these previous hypotheses, a novel tritrophic hypothesis is introduced that proposes that foliar nyctinasty constitutes an indirect plant defence against nocturnal herbivores. It is suggested that the reduction in physical clutter that follows from nocturnal leaf closure may increase the foraging success of many types of animals that prey upon or parasitise herbivores. Predators and parasitoids generally use some combination of visual, auditory or olfactory cues to detect prey. In terrestrial environments, it is hypothesised that the vertical orientation of the blades of nyctinastic plants at night would be especially beneficial to flying nocturnal predators (e.g. bats and owls) and parasitoids whose modus operandi is death from above. The movements of prey beneath a plant with vertically oriented foliage would be visually more obvious to gleaning or swooping predators under nocturnal or crepuscular conditions. Such predators could also detect sounds made by prey better without baffling layers of foliage overhead to damp and disperse the signal. Moreover, any volatiles released by the prey would diffuse more directly to the awaiting olfactory apparatus of the predators or parasitoids. In addition to facilitating the demise of herbivores by carnivores and parasitoids, foliar nyctinasty, much like the enhanced illumination of the full moon, may mitigate feeding by nocturnal herbivores by altering their foraging behaviour. Foliar nyctinasty could also provide a competitive advantage by encouraging herbivores, seeking more cover, to forage on or around non‐nyctinastic species. As an added advantage, foliar nyctinasty, by decreasing the temperature between plants through its effects on re‐radiation, may slow certain types of ectothermic herbivores making them more vulnerable to predation. Foliar nyctinasty also may not solely be a behavioural adaptation against folivores; by discouraging foraging by granivores, the inclusive fitness of nyctinastic plants may be increased. [ABSTRACT FROM AUTHOR]

The ungulate-carnivore-vulture complex is a key trophic module of many terrestrial ecosystems, but one that is globally under threat. Few have explored cross-species dependencies in this module, and the degree to which vultures rely on trophic facilitation by apex carnivores is rarely known and almost never quantified., We investigated the importance of puma Puma concolor predation on its native camelid prey, vicuñas Vicugna vicugna and guanacos Lama guanicoe, in food provisioning for Andean condors Vultur gryphus in the high Andes of north-western Argentina. We evaluated the origin of wild food sources through carcass surveys. We quantified condor feeding habits via foraging observations and through the analysis of pellet contents and stable isotopes from moulted feathers., Of the 102 fresh camelid carcasses we monitored, nearly all (94%) resulted from puma predation, and the majority (85%) of camelid carcasses used by condors were killed by pumas. Camelids represented 88% of the prey items identified from 183 condor pellets, and isotopic analyses of moulted feathers from 86 individuals identified via multilocus genotyping revealed that camelids and Small livestock were the most important prey items, representing 45-58% and 28-38% of condor assimilated biomass, respectively., Synthesis and applications. Our results show that puma predation plays a key role in the foraging ecology of Andean condors, and highlight the importance of predatory processes that make carrion available to scavengers. We contend that targeting the conservation of ungulate-carnivore-vulture modules, rather than a species-specific approach, will be a more effective strategy to ensure the long-term persistence of Andean condors and other obligate scavengers. [ABSTRACT FROM AUTHOR]

Across diverse ecosystems, greater climatic variability tends to increase wildfire size, particularly in Australia, where alternating wet-dry cycles increase vegetation growth, only to leave a dry overgrown landscape highly susceptible to fire spread. Aboriginal Australian hunting fires have been hypothesized to buffer such variability, mitigating mortality on small-mammal populations, which have suffered declines and extinctions in the arid zone coincident with Aboriginal depopulation. We test the hypothesis that the relationship between climate and fire size is buffered through the maintenance of an anthropogenic, fine-grained fire regime by comparing the effect of climatic variability on landscapes dominated by Martu Aboriginal hunting fires with those dominated by lightning fires. We show that Aboriginal fires are smaller, more tightly clustered, and remain small even when climate variation causes huge fires in the lightning region. As these effects likely benefit threatened small-mammal species. Aboriginal hunters should be considered trophic facilitators, and policies aimed at reducing the risk of large fires should promote land-management strategies consistent with Aboriginal burning regimes. [ABSTRACT FROM AUTHOR]

Abstract: This study investigated the role of the American oystercatcher (Haematopus palliatus) as a resource subsidizer for the scavenger snail Buccinanops globulosum in a northern Patagonian bay (40°45′S, 64°56′W, San Antonio Bay, Argentina). The most frequent food item for the snails was dead crabs Cyrtograpsus angulatus Dana, and the snails preferred this item. In the field, most dead crabs (78%) resulted from oystercatcher predation. Field densities of dead crabs were within the 95% confidence limits of the estimated densities produced by oystercatcher foraging activity, suggesting that a large proportion of carrion available for snails is a byproduct of oystercatcher predation. Dead crabs with injuries were more rapidly detected and consumed by snails, probably because injuries produced by oystercatchers increase leakage of body fluids and facilitate penetration of the proboscis of the snails. Our results suggest that oystercatcher predation subsidize this scavenger snail by increasing availability of food, decreasing variability in their provision and facilitating their consumption. [Copyright &y& Elsevier]