Streamwater nutrients stimulate respiration and breakdown of standardized detrital substrates across a landscape gradient: Effects of nitrogen, phosphorus, and carbon quality

Usher, Rachel L.; Wood, James; Bumpers, Phillip M.; Wenger, Seth J.; Rosemond, Amy D.

doi:10.1086/707598

Cited by 9 publications

(9 citation statements)

References 33 publications

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“…Although nutrient content increased on all OM types with enrichment, there were greater magnitude changes in %P than in %N. Greater change in P vs. N content of substrates in our study is consistent with others conducted at Coweeta (Rosemond et al 2008; Tant et al 2013; Kominoski et al 2015) and across nutrient gradients elsewhere in the United States (O'Brien and Wehr 2010; Taylor et al 2014; García et al 2017; Usher et al 2020). Greater effects on P than on N occurred in both algal and detrital substrates, likely due to greater potential for sequestration of P than N when both were available (Gulis et al 2017; Danger 2020).…”

Section: Discussionsupporting

confidence: 89%

Experimental nutrient enrichment of forest streams reduces ecosystem nitrogen and phosphorus storage

Bumpers

Rosemond

Manning

et al. 2023

Limnology & Oceanography

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Streams store nutrients in standing stocks of organic matter (OM) and associated biologically sequestered elements. Unlike standing stocks of autotrophs, detritus is depleted by nutrient enrichment, potentially reducing areal storage of detritus‐associated nutrients. To test effects of nutrient‐loading on storage of nitrogen (N) and phosphorus (P) by autotrophic and detrital‐pool compartments, we quantified the effects of 2 yr of continuous experimental N and P additions on fine benthic organic matter (FBOM), leaves, wood, and biofilms in five forest streams. Our design tested the relative strength of N vs. P on OM nutrient content, areal OM storage, and areal nutrient storage in OM types. Enrichment increased nutrient content of all OM types; %P increased more than %N in leaves, wood, and biofilms, but not FBOM. Biofilm %P and %N increased more than in all detrital types. Areal FBOM and leaf storage declined with nutrient enrichment. Biofilm standing stocks were generally higher with enrichment but were not related to the streamwater N and P gradients. Despite increased OM nutrient content, total areal nutrient storage in leaves and wood decreased due to reduced OM storage. Although annual nutrient storage was stabilized by FBOM, seasonal variation in nutrient storage increased with enrichment. Leaf‐associated nutrient storage was reduced in most seasons, whereas FBOM and biofilm nutrient storage increased in winter and spring, respectively, relative to pretreatment. Overall, the combined responses of all OM types to enrichment resulted in reduced storage and altered seasonal availability of carbon and nutrients, which has implications for consumers and downstream processes.

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Section: Discussionsupporting

confidence: 89%

Experimental nutrient enrichment of forest streams reduces ecosystem nitrogen and phosphorus storage

Bumpers

Rosemond

Manning

et al. 2023

Limnology & Oceanography

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“…This would occur in any ecosystem in which other factors such as altered hydrology or excess contaminants did not otherwise suppress microbial uptake and sequestration of nutrients. Such patterns have been shown to be robust in studies determining nutrient‐resource stoichiometry relationships for both biofilms and wood across moderate land‐use gradients (O'Brien & Wehr, 2010; Usher, Wood, Bumpers, Wenger, & Rosemond, 2020).…”

Section: Discussionmentioning

confidence: 87%

Experimental N and P additions relieve stoichiometric constraints on organic matter flows through five stream food webs

Demi

Benstead

Rosemond

et al. 2020

Journal of Animal Ecology

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1. Human activities have dramatically altered global patterns of nitrogen (N) and phosphorus (P) availability. This pervasive nutrient pollution is changing basal resource quality in food webs, thereby affecting rates of biological productivity and the pathways of energy and material flow to higher trophic levels.2. Here, we investigate how the stoichiometric quality of basal resources modulates patterns of material flow through food webs by characterizing the effects of experimental N and P enrichment on the trophic basis of macroinvertebrate production and flows of dominant food resources to consumers in five detritus-based stream food webs.3. After a pre-treatment year, each stream received N and P at different concentrations for 2 years, resulting in a unique dissolved N:P ratio (target range from 128:1 to 2:1) for each stream. We combined estimates of secondary production and gut contents analysis to calculate rates of material flow from basal resources to macroinvertebrate consumers in all five streams, during all 3 years of study.4. Nutrient enrichment resulted in a 1.5× increase in basal resource flows to primary consumers, with the greatest increases from biofilms and wood. Flows of most basal resources were negatively related to resource C:P, indicating widespread P limitation in these detritus-based food webs. Nutrient enrichment resulted in a greater proportion of leaf litter, the dominant resource flow-pathway, being consumed by macroinvertebrates, with that proportion increasing with decreasing leaf litter C:P. However, the increase in efficiency with which basal resources were channelled into metazoan food webs was not propagated to macroinvertebrate predators, as flows of prey did not systematically increase following enrichment and were unrelated to basal resource flows.5. This study suggests that ongoing global increases in N and P supply will increase organic matter flows to metazoan food webs in detritus-based ecosystems by reducing stoichiometric constraints at basal trophic levels. However, the extent to which those flows are propagated to the highest trophic levels likely depends on responses of individual prey taxa and their relative susceptibility to predation. K E Y W O R D S detritus, ecological stoichiometry, food webs, nitrogen, nutrient pollution, phosphorus, secondary production, streams Additional supporting information may be found online in the Supporting Information section. How to cite this article: Demi LM, Benstead JP, Rosemond AD, Maerz JC. Experimental N and P additions relieve stoichiometric constraints on organic matter flows through five stream food webs.

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“…All SHI geometries had a volume of 231 cm 3 , such that mass (a metric of energy availability) was constant among them. Cellulose sponges were chosen because this carbon-based material may be readily utilised by marine microbes as an energetic (food) source (Royer et al, 2021;Usher et al, 2020), allowing bacterial films to develop that in turn serve as an energy source for non-cellulose-consuming species.…”

Section: Sample Preparationmentioning

confidence: 99%

Isolating the drivers of the species‐area relationship in experimental habitat islands

Hanks,

Clay,

Herrmann

et al. 2023

Journal of Biogeography

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AimConsidered one of ecology's laws, the species‐area relationship (SAR) is among the most intensively studied ecological phenomena, yet the mechanisms through which the SAR arises and under what circumstances remain poorly understood. Here, we experimentally test the effects of area alone in the absence of commonly invoked mechanistic drivers of the SAR in both sub‐tidal bay and inter‐tidal marsh habitats.LocationLouisiana, U.S.A.TaxonInvertebrate macrofauna.MethodsTo determine if surface area alone may generate the SAR, we conducted a small‐scale, ephemeral habitat island experiment in a subtidal soft‐bottom bay and in an intertidal soft‐bottom coastal salt marsh. Cellulose sponge habitat islands of varying surface areas, but with constant energy content and habitat diversity, were deployed in each location to isolate the effects of surface area on the SAR in the absence of species‐energy relationships and habitat diversity.ResultsArea alone, likely through passive sampling, generated significant SARs in both habitats, with the salt marsh producing the strongest relationship, likely due to differential physical structuring between habitats. Communities of low surface area sponges were generally nested within those of high surface area sponges, and dispersal limitation may have increased the importance of nestedness relative to species replacements in structuring communities between habitats.Main ConclusionsThat area alone, in the absence of covariates such as energy availability and habitat diversity may, significantly impact the species richness of experimental and ephemeral marine benthic habitat island communities. Our methodology may provide a new avenue for SAR research, allowing for the isolation and simultaneous testing of potential drivers through the physical manipulation of ephemeral habitats.

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Streamwater nutrients stimulate respiration and breakdown of standardized detrital substrates across a landscape gradient: Effects of nitrogen, phosphorus, and carbon quality

Cited by 9 publications

References 33 publications

Experimental nutrient enrichment of forest streams reduces ecosystem nitrogen and phosphorus storage

Experimental nutrient enrichment of forest streams reduces ecosystem nitrogen and phosphorus storage

Experimental N and P additions relieve stoichiometric constraints on organic matter flows through five stream food webs

Isolating the drivers of the species‐area relationship in experimental habitat islands

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