Predator control of ecosystem nutrient dynamics

Abstract

Predators are predominantly valued for their ability to control prey, as indicators of high levels of biodiversity and as tourism attractions. This view, however, is incomplete because it does not acknowledge that predators may play a significant role in the delivery of critical life-support services such as ecosystem nutrient cycling. New research is beginning to show that predator effects on nutrient cycling are ubiquitous. These effects emerge from direct nutrient excretion, egestion or translocation within and across ecosystem boundaries after prey consumption, and from indirect effects mediated by predator interactions with prey. Depending on their behavioural ecology, predators can create heterogeneous or homogeneous nutrient distributions across natural landscapes. Because predator species are disproportionately vulnerable to elimination from ecosystems, we stand to lose much more from their disappearance than their simple charismatic attractiveness.

Caught in the web: Spider web architecture affects prey specialization and spider–prey stoichiometric relationships

“…Some studies also suggest that nonprotein energy (carbohydrates and lipids) may play an important role in predator population dynamics (Simpson et al., 2015). Furthermore, recent research is beginning to show the strong effects that predators have on ecosystem‐level processes (Schmitz, Hawlena, & Trussell, 2010), and the consequences of elemental imbalances in predator–prey interactions on the ratios of elements recycled by predators (Munshaw, Palen, Courcelles, & Finlay, 2013). As shown in this study, stoichiometric differences between spiders and prey caused elemental imbalances in predator–prey interactions.…”

Predator‐driven elemental cycling: the impact of predation and risk effects on ecosystem stoichiometry

“…2007; Leroux and Loreau 2010; Schmitz et al. 2010). Our focus here is on how predators affect the distribution of elements among trophic compartments within ecosystems.…”

“…2009; Schmitz et al. 2010). The quantity of C or N egested and excreted can vary because of differential assimilation to maintain homeostasis.…”

“…1979; DeAngelis 1992; Vanni 2002; Schmitz et al. 2010; Dalton and Flecker 2014). Ecological stoichiometry has enhanced understanding of the mechanisms driving consumer‐mediated elemental transfer and recycling by explicitly connecting organismal‐based physiology to this whole ecosystem process (Sterner and Elser 2002).…”

“…1979; Pomeroy 2001; Schmitz et al. 2008, 2010). Evading predation can reduce foraging effort, which may also constrain the transfer rate of elements up the trophic chain (Trussell et al.…”