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Procedures to obtain skin secretions in frogs may induce stress from handling or injection with stress-associated hormones (norepinephrine). We investigated the metabolic costs of procedures used to assess amphibian antimicrobial capacity and skin microbiome. We randomly assigned 48 adult coqui frogs (Eleutherodactylus coqui) to four treatments: microbiome depletion, antimicrobial peptide (AMP) depletion, microbiome and AMP depletion, and an unmanipulated control group. Microbiome depletion was achieved by soaking frogs in an antibiotic cocktail bath, whereas the AMP depletion was done by injection of norepinephrine followed by a buffer bath. We used a flow-through Sable Systems Field Metabolic System to collect respirometry data following a 30-minute acclimation period to respirometry chambers. Respirometry data were collected at three timepoints: (1) Baseline at 2-3 weeks prior to treatment; (2) Post-treatment representing 2 days after AMP depletion and 4 days after microbiome depletion; and (3) Final data at 6 weeks post-treatment. Then, to assess the effects of norepinephrine injection at a shorter timescale, a subset of 24 frogs that had not previously experienced AMP depletion were assigned to either AMP depletion or a buffer bath-only control group. Respirometry data collection began without acclimation to respirometry chambers, immediately after removing frogs from buffer baths. Over the 6-week period, we found no consistent treatment effects on metabolism in coqui frogs. At the shorter timescale, metabolism increased with time-since-handling and after norepinephrine injection. Our results show that standard procedures predicted to increase stress at the individual level do not have a lasting effect on whole-frog metabolism. 

Abstract Earth System Models (ESMs) are essential tools for understanding and predicting global change, but they cannot explicitly resolve hillslope‐scale terrain structures that fundamentally organize water, energy, and biogeochemical stores and fluxes at subgrid scales. Here we bring together hydrologists, Critical Zone scientists, and ESM developers, to explore how hillslope structures may modulate ESM grid‐level water, energy, and biogeochemical fluxes. In contrast to the one‐dimensional (1‐D), 2‐ to 3‐m deep, and free‐draining soil hydrology in most ESM land models, we hypothesize that 3‐D, lateral ridge‐to‐valley flow through shallow and deep paths and insolation contrasts between sunny and shady slopes are the top two globally quantifiable organizers of water and energy (and vegetation) within an ESM grid cell. We hypothesize that these two processes are likely to impact ESM predictions where (and when) water and/or energy are limiting. We further hypothesize that, if implemented in ESM land models, these processes will increase simulated continental water storage and residence time, buffering terrestrial ecosystems against seasonal and interannual droughts. We explore efficient ways to capture these mechanisms in ESMs and identify critical knowledge gaps preventing us from scaling up hillslope to global processes. One such gap is our extremely limited knowledge of the subsurface, where water is stored (supporting vegetation) and released to stream baseflow (supporting aquatic ecosystems). We conclude with a set of organizing hypotheses and a call for global syntheses activities and model experiments to assess the impact of hillslope hydrology on global change predictions.