Leaf-litter stoichiometry is affected by streamwater phosphorus concentrations and litter type

Scott, Erin E.; Prater, Clay; Norman, Eric J.; Baker, Bryant C.; Evans‐White, Michelle A.; Scott, J. Thad

doi:10.1899/12-215.1

Cited by 31 publications

(35 citation statements)

References 49 publications

(72 reference statements)

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“…Increased P concentrations often stimulate microbial biomass and nutrient content, lowering litter C:P and C: N over decomposition (Scott et al, 2013;Manning et al, 2015). In our study, litter C:P stabilised late into decomposition in the moderate-and high-P treatments under both light regimes, achieving minimum C:P of 1050 and 495 under low light, respectively and 1930 and 194 under high light, respectively. In the high-P treatments, the significantly lower C:P of leaf litter from high light versus low light indicates greater total P content in microbial biofilm, presumably due to enhanced total microbial biomass and/or enhanced storage of P by algae.…”

Section: Responsesupporting

confidence: 46%

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Light and dissolved phosphorus interactively affect microbial metabolism, stoichiometry and decomposition of leaf litter

et al. 2016

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Summary In aquatic settings, light can stimulate algal growth to affect microbial transformation of organic substrates. These effects may depend on dissolved nutrients that differentially constrain microbial autotrophy and heterotrophy to drive contrasting carbon (C) and phosphorus (P) dynamics during decomposition. We incubated sugar maple (Acer saccharum) litter under three dissolved P amendments (0, 50 or 500 μg L−1 P) and two light levels (14 or 475 μmol photons m−2 s−1) in laboratory microcosms. We measured litter chlorophyll a, microbial respiration and net metabolism, carbon:nitrogen (C:N) and C:P content, microbial P uptake and release and litter decomposition over 134 days. Elevated dissolved P increased algal biomass in the high‐light treatment and magnified net heterotrophy and autotrophy in the low‐ and high‐light treatments, respectively. Litter C:P and C:N declined as dissolved P increased, and litter C:P was further reduced by high light only in the highest P treatment. Microbial P uptake fluxes peaked under moderate P and high light, whereas P release fluxes were consistently low throughout the experiment. The percent of P uptake that was released was significantly higher under low light. High light stimulated decomposition under low P but slowed decomposition under high P, suggesting increased nutrients weakened algal priming of litter decomposition. Our study suggests factors controlling the degree of autotrophy versus heterotrophy on organic matter, such as light and nutrient availability, may interactively shift litter C and P dynamics during decomposition.

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Section: Responsesupporting

confidence: 46%

“…We expected that (ii) litter C:P and C:N content would decrease through time and in proportion to the level of P enrichment (Scott et al, 2013). We conducted a fully-factorial laboratory experiment with sugar maple (Sapindaceae: Acer saccharum) litter incubated for 134 days under three dissolved P amendments and two light regimes.…”

Section: Introductionmentioning

confidence: 99%

Light and dissolved phosphorus interactively affect microbial metabolism, stoichiometry and decomposition of leaf litter

et al. 2016

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“…Fungi assimilate nutrients from the water column to overcome the high C:nutrient ratios typical of dead organic matter and meet their elemental requirements, as shown by both laboratory and field experiments on fungi from streams (Cross et al, 2007;Cheever et al, 2012;Scott et al, 2013;Pastor et al, 2014). Increasing N and P concentrations of decomposing leaf litter generally correspond to increases in fungal biomass (Kaushik and Hynes, 1971;Gessner, 1991;Gessner et al, 1993).…”

Section: Effects Of Aquatic Fungi On Leaf Litter Stoichiometrymentioning

confidence: 99%

Ecological stoichiometry of aquatic fungi: current knowledge and perspectives

2016

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“…However, below C ∶ P = 1620, diets may induce C limitation to reduce growth. This induction may occur at ecologically relevant levels of P enrichment because diets fed to P. lepida spanned the range in mixed litter C ∶ P in Ozark streams (Scott et al 2013). The mechanism of reduced growth below diet C ∶ P = 1620 is unclear, but slight decreases in consumption may play a role, perhaps because of nutrient satiation (Plath and Boersma 2001).…”

Section: Volume 34mentioning

confidence: 99%

A stream insect detritivore violates common assumptions of threshold elemental ratio bioenergetics models

et al. 2015

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Ecologists increasingly use threshold elemental ratios (TERs) to explain and predict organism responses to altered resource C ∶ P or C ∶ N. TER calculations are grounded in diet-dependent growth, but growth data are limited for most taxa. Thus, TERs are derived instead from bioenergetics models that rely on simplifying assumptions, such as fixed organism C ∶ P and no P excretion at peak growth. We examined stoichiometric regulation of the stream insect detritivore Pycnopsyche lepida to assess bioenergetics model assumptions and compared bioenergetics TER C ∶ P estimates to those based on growth. We fed P. lepida maple and oak leaf diets along a dietary C ∶ P gradient (molar C ∶ P range = 950-4180) and measured consumption, growth, stoichiometric homeostasis (H), and elemental assimilation and growth efficiencies over a 5-wk period in the laboratory. Pycnopsyche lepida responses to varying resource C ∶ P depended on litter identity and were strongest among oak diets, on which growth peaked at diet C ∶ P = 1620. Pycnopsyche lepida fed oak litter exhibited flexible body C ∶ P during growth and in response to altered diet C ∶ P (non-strict homeostasis; H = 4.74), low P use efficiencies, and P excretion at peak growth. These trends violated common bioenergetics model assumptions and caused deviation of estimated TER C ∶ P from C ∶ P = 1620. Bioenergetics TER C ∶ P further varied among P. lepida of differing growth status on varying diet C ∶ P (overall TER C ∶ P range = 1030-9540). Our study identifies novel effects of nutrient enrichment and litter identity on detritivore stoichiometric regulation and supports growth-based approaches for future TER calculations.

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Leaf-litter stoichiometry is affected by streamwater phosphorus concentrations and litter type

Cited by 31 publications

References 49 publications

Light and dissolved phosphorus interactively affect microbial metabolism, stoichiometry and decomposition of leaf litter

Light and dissolved phosphorus interactively affect microbial metabolism, stoichiometry and decomposition of leaf litter

Ecological stoichiometry of aquatic fungi: current knowledge and perspectives

A stream insect detritivore violates common assumptions of threshold elemental ratio bioenergetics models

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