Threshold elemental ratios of carbon and phosphorus in aquatic consumers

Abstract

Inadequate supply of one or more mineral elements can slow the growth of animal consumers and alter their physiology, life history and behaviour. A key concept for understanding nutrient deficiency in animals is the threshold elemental ratio (TER), at which growth limitation switches from one element to another. We used a stoichiometric model that coupled animal bioenergetics and body elemental composition to estimate TER of carbon and phosphorus (TER(C:P)) for 41 aquatic consumer taxa. We found a wide range in TER(C:P) (77-3086, ratio by atoms), which was generated by interspecific differences in body C : P ratios and gross growth efficiencies of C. TER(C:P) also varied among aquatic invertebrates having different feeding strategies, such that detritivores had significantly higher threshold ratios than grazers and predators. The higher TER(C:P) in detritivores resulted not only from lower gross growth efficiencies of carbon but also reflected lower body P content in these consumers. Supporting previous stoichiometric theory, we found TER(C:P) to be negatively correlated with the maximum growth rate of invertebrate consumers. By coupling bioenergetics and stoichiometry, this analysis revealed strong linkages among the physiology, ecology and evolution of nutritional demands for animal growth.

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

“…(2004), for example, the C:N TER in a predator–prey interaction is given by: ${\text{TER}}_{\mathrm{C}:\mathrm{N}}=false(\text{C:N prey}false/\text{C:N predator}false)>{\mathrm{normal\alpha }}_{\mathrm{normalN}}/{\mathrm{normal\alpha }}_{\mathrm{normalC}}$where C:N prey and C:N predator are the C:N in prey and predator biomass, and α N is the maximum gross growth efficiency for N (i.e., fraction of ingested N that the predator converts into new biomass), α C is the maximum gross growth efficiency for C (i.e., fraction of ingested C that the predator converts into new biomass). To calculate the TER for each spider, we used a gross growth efficiency α C  = 0.65 C and α N  = 0.70 (Fagan & Denno, 2004; Fagan et al., 2002; Matsumura et al., 2004; Wiesenborn, 2013), and two values for α PL  = 0.6 (low maximum gross growth efficiency; Lehman, 1993) and α PH (high maximum gross growth efficiency; DeMott, Gulati, & Siewertsen, 1998; Frost et al., 2006). Values for α N /α C  = 1.077, α PL /α C  = 0.923, α PH /α C  = 1.333, and α PL /α N  = 0.857, and α PH /α N  = 1.143.…”

Unifying ecological stoichiometry and metabolic theory to predict production and trophic transfer in a marine planktonic food web

“…Such a short time span was presumably not sufficient to lead to strong food quality effects on reproduction and thus abundance. While low food quality may induce enhanced (compensatory) feeding immediately, the 9 days of grazing in our experiment might not have been sufficient for the counteracting negative effects on consumer growth efficiency [11,21] to offset compensatory feeding via reduced population size for most consumer treatments and temperatures. At 248C, consumer growth was most strongly negatively affected by low food quality in the experiment (see below).…”

“…Phototrophs, unlike herbivores, can adjust their elemental composition depending on nutrient stoichiometry, resulting in different food quality and thus affecting consumption rates and consumer nutrient recycling [8]. In community ecology, ES has successfully been used to explain consumer performance (food uptake rate, assimilation, growth rate and efficiency; [9][10][11]), competition between consumer species [12,13], and consumer effects on prey nutrient composition [14,15]. In contrast to ES, MTE [16] focuses on consumer body mass and temperature as determinants of metabolic rates, which control growth and consumption rates as well as population and community productivity.…”

Interactive effects of predation risk and conspecific density on the nutrient stoichiometry of prey

“…The rationale behind this hypothesis derives from the notion of organism threshold elementary ratio (TER) (Frost et al. 2006), which represents the elementary ratio of resources that shifts the nutrient limitation of an organism. The explicit formulation of an organism's TER of C to nutrients is ${\text{TER}}_{\mathrm{C}:\mathrm{N}}=\frac{A_{\mathrm{N}}}{{\text{GGE}}_{\mathrm{C}}}\frac{Q_{\mathrm{C}}}{Q_{\mathrm{N}}}$where A N represents nutrient assimilation efficiency, GGE C represents the gross growth efficiency of C, and Q C and Q N represent the organism's body quantity of C and nutrients, respectively.…”