PREY DENSITIES VS PREDATORS DRIVERS

Finally, the “ecology of fear” framework posits that the presence of predators can mobilize stress hormone secretion and consequently decrease prey energetic reserves 19, 20. This feeding behaviour is an important component of consumer-resource interactions that can influence population dynamics and predator-prey co-evolution 15, 16, 17, 18. Predators can also abandon or only partially consume some of the killed prey, a widespread behaviour in many invertebrate and vertebrate predators referred to as surplus killing 12, 13, 14. Predator attacks are not always successful and injured prey sometime escape and die later away from the predator 10, 11. However, prey also face predation-induced types of death other than direct consumption by predators.

Altogether, these temperature- and density-dependent effects on predation rates can alter population dynamics and species persistence by modifying trophic interaction strengths 9. The effects of prey density are caused by the non-linearity of the predator feeding rate that increases with prey density and reaches a plateau at high prey densities (i.e., saturating Holling type II or III functional responses). Thermal effects on predation rate are mainly driven by the acceleration of physiological processes (metabolism and digestion) leading to higher energetic demands of the predators, and by more frequent predator-prey encounters due to faster movement of predators or prey with warming. For example, previous studies have shown that predation rate often increases with temperature but decreases with prey density 5, 6, 7, 8.

PREY DENSITIES VS PREDATORS DRIVERS

A growing number of studies have thus investigated the effects of global change drivers such as temperature, enrichment, pollutants, and habitat fragmentation on trophic interactions 1, 2, 3, 4. Investigating the effects of environmental drivers on food webs is crucial to better understand global change impacts on energy and nutrient fluxes across trophic levels. This suggests that environmental changes such as climate warming and reduced resource availability could increase the efficiency of energy transfer in food webs only if functionally diverse predator communities are conserved. Our results indicate that energy transfer across trophic levels is more efficient due to lower NCM in functionally diverse predator communities, at lower resource densities and at higher temperatures. Warming significantly reduced NCM only in the dragonfly larvae but the magnitude depended on dragonfly larvae density. We found that NCM increased with prey density and depended on the functional diversity and density of the predator community. virginalis) preying on common carp ( Cyprinus carpio) fry. We investigated the effects of temperature, prey density, and predator diversity and density on NCM in an aquatic food web module composed of dragonfly larvae ( Aeshna cyanea) and marbled crayfish ( Procambarus fallax f.

However, the biotic and abiotic factors influencing this mortality component remain largely unexplored, leaving a gap in our understanding of the impacts of environmental change on ecological communities. Nonconsumptive predator-driven mortality (NCM), defined as prey mortality due to predation that does not result in prey consumption, is an underestimated component of predator-prey interactions with possible implications for population dynamics and ecosystem functioning.

Prey densities vs predators