Temperature is a critical environmental variable for ecosystem processes, since metabolic rates of organisms increase with temperature, which could potentially elevate their excretion rates. In a warming climate, it is imperative to understand how temperature influences consumers' nutrient excretion, especially nitrogen (N) and phosphorus (P). Here, we review, quantify and synthesize the effect sizes of temperature on nutrient excretion rates of freshwater fishes through a meta‐analysis. Because there are too few studies measuring fish P excretion under different temperatures, we could only test the temperature effect on N excretion rates. Overall, our results show that fish N excretion increases with temperature, but there is considerable variability between studies. We investigated the nature of this heterogeneity by testing the influence of fish body size, climate (tropical, subtropical, temperate), delta temperature (difference between the lowest and highest temperature used in the experiment), acclimatization time, and feeding status (being fed or starved before excretion measurements) as moderators (predictors in meta‐analysis). We found that delta temperature and feeding status significantly influenced the magnitude of the effect, with studies applying the highest delta temperatures, and studies with starved fish, showing the highest effect sizes. Our meta‐analysis suggests that the magnitude of temperature increase and food availability can partly determine how global warming will affect fishes' N excretion in freshwater ecosystems.

In tropical ecosystems impacted by deforestation, isolated trees play a critical role in sustaining terrestrial biodiversity, but their effects on aquatic communities remain poorly understood. These trees create a unique microclimate that can influence pond formation, benefiting amphibians that rely on water bodies for reproduction, in turn affecting community structure, trophic networks, and energy cycling. In this study, our goal was to assess how isolated trees influence tadpole assemblage structure and secondary production. We established an experimental system with 12 artificial ponds in a pasture area of the Atlantic Forest in Brazil, divided into 3 treatments: 4 in open pasture, 4 near the edge of continuous forest, and 4 under isolated trees. We recorded 12 anuran species, mostly belonging to the Hylidae family, and calculated the secondary production of the entire assemblage over a full breeding season. Isolated trees increased resource diversity but did not affect species composition or secondary production. However, we found a temporal effect on species composition, suggesting rapid turnover in assemblage structure that maintained secondary production similarly across treatments. This study, which is the 1st tropical study to provide assemblage-wide estimates of tadpole secondary production, provides higher secondary production values than previous species-level studies because of this study's greater tadpole densities and biomass, and because of the high water temperatures (up to 35 degrees C). Although isolated trees did not boost overall production, they modulated environmental conditions that may affect broader ecosystem processes beyond tadpole assemblages. Our findings emphasize conserving ponds and different elements of the pasture-dominated landscape to ensure habitat heterogeneity to support species-specific reproductive strategies and preserve aquatic-terrestrial linkages, which are critical for ecosystem resilience amid deforestation and amphibian declines. Em ecossistemas tropicais impactados pelo desmatamento, & aacute;rvores isoladas desempenham um papel cr & iacute;tico na manuten & ccedil;& atilde;o da biodiversidade terrestre, mas seus efeitos sobre as comunidades aqu & aacute;ticas ainda s & atilde;o pouco compreendidos. Essas & aacute;rvores criam um microclima singular que pode influenciar a forma & ccedil;& atilde;o de po & ccedil;as, beneficiando anf & iacute;bios que dependem de corpos d'& aacute;gua para a reprodu & ccedil;& atilde;o e, consequentemente, afetando a estrutura da comunidade, as redes tr & oacute;ficas e a ciclagem de energia. Neste estudo, nosso objetivo foi avaliar como & aacute;rvores isoladas influenciam a estrutura da assembleia de girinos e a produ & ccedil;& atilde;o secund & aacute;ria. Estabelecemos um sistema experimental com 12 po & ccedil;as artificiais em uma & aacute;rea de pastagem na Mata Atl & acirc;ntica, no Brasil, divididas em 3 tratamentos: 4 em pastagem aberta, 4 pr & oacute;ximas & aacute; borda de uma floresta cont & iacute;nua e 4 sob & aacute;rvores isoladas. Registramos 12 esp & eacute;cies de anuros, predominantemente da fam & iacute;lia Hylidae, e calculamos a produ & ccedil;& atilde;o secund & aacute;ria de toda a assembleia ao longo de uma estac & ccedil;& atilde;o reprodutiva completa. As & aacute;rvores isoladas aumentaram a diversidade de recursos, mas n & atilde;o afetaram a composi & ccedil;& atilde;o de esp & eacute;cies nem a produ & ccedil;& atilde;o secund & aacute;ria. No entanto, observamos um efeito temporal sobre a composi & ccedil;& atilde;o de esp & eacute;cies, sugerindo uma r & aacute;pida substitui & ccedil;& atilde;o na estrutura da assembleia que manteve a produ & ccedil;& atilde;o secund & aacute;ria semelhante entre os tratamentos. Este estudo, o primeiro em ambiente tropical a fornecer estimativas de produ & ccedil;& atilde;o secund & aacute;ria em n & iacute;vel de assembleia de girinos, apresenta valores de produ & ccedil;& atilde;o secund & aacute;ria mais elevados do que estudos anteriores em n & iacute;vel de esp & eacute;cie, devido & aacute;s maiores densidades e biomassa de girinos observadas, bem como & aacute;s altas temperaturas da & aacute;gua (at & eacute; 35 degrees C). Embora as & aacute;rvores isoladas n & atilde;o tenham aumentado a produ & ccedil;& atilde;o total, elas modularam as condi & ccedil;& otilde;es ambientais, o que pode afetar processos ecossist & ecirc;micos mais amplos para al & eacute;m das assembleias de girinos. Nossos resultados ressaltam a import & acirc;ncia da conserva & ccedil;& atilde;o de po & ccedil;as e de diferentes elementos da paisagem dominada por pastagens para garantir a heterogeneidade de habitats, apoiar estra & eacute;gias reprodutivas espec & iacute;ficas das esp & eacute;cies e preservar as conex & otilde;es aqu & aacute;tico-terrestres, fundamentais para a resili & ecirc;ncia dos ecossistemas diante do desmatamento e do decl & iacute;nio de anf & iacute;bios.

Abstract All organisms contain carbon, nitrogen, and phosphorus in widely ranging amounts and proportions. Integrating existing datasets enables quantification of this variation at global scales. Such efforts could leverage ecological stoichiometry theory, the study of elemental supply and imbalances in ecological interactions, to connect ecological drivers and taxonomic constraints to ecosystem structure and function. Towards this goal, we developed the Limnology Stoichiometric Traits of Organisms In their Chemical Habitats (Limno‐STOICH) database. The Limno‐STOICH database includes 51,576 observations of organismal elemental stoichiometry from >3100 rivers, lakes, wetlands, and other aquatic ecosystem sites on seven continents, derived from 190+ sources. It also includes extensive spatial and temporal metadata to link elemental stoichiometry with ecosystem type, trophic status, etc., and information on organismal data (body size, taxonomic classifications, stable isotope composition) and water physicochemical parameters. The Limno‐STOICH database sets the stage for significant applications across food web ecology, evolutionary ecology, biogeochemistry, and other disciplines.

The demanding nature of conservation biology, with extensive fieldwork and travel, disproportionately affects work-life balance, exacerbating gender disparities in leadership. Diversity and inclusivity enhance conservation outcomes, yet women remain underrepresented in senior roles, facing intersectional barriers tied to gender, race, and socioeconomic factors, especially in the Global South. To better understand the factors influencing women’s success in conservation science leadership, we analyzed the career experiences of professionals across the globe. Our study compared the professional journeys of men and women leaders while identifying the main obstacles they encounter in reaching leadership positions. We identified 556 research leaders based on criteria related to high-impact publications, awards, conference attendance, and academic affiliation. Among them, fewer than 30% were women. We sent an online questionnaire by email to all leaders, addressing both personal and professional aspects (e.g., demographic and academic background). A total of 118 researchers responded (54 women and 64 men). We found that men and women in conservation science leadership recognize distinct challenges on their journey to leadership. While 62% of women cited family balance and gender issues as key hurdles, men reported systematic challenges like funding and academic constraints. Men and women had similar life histories with no differences in age at marriage, parenthood timing, or partner’s career. A higher proportion of women (22%) than men (14%) were childless. Our findings call for institutions to adopt inclusive policies, such as work-life balance measures, fair promotions, and stronger mentorship networks, to alleviate women’s disproportionate burdens, close gender gaps, and retain women leaders.

The elemental content of organisms links cellular biochemistry to ecological processes, from physiology to nutrient dynamics. While plant stoichiometry is thought to vary with climate and nutrient availability across latitudes, the consistency of these patterns across trophic groups and realms remains unclear. Using the StoichLife database, which includes nitrogen and phosphorus content data for 5443 species across 1390 sites, we examine how solar energy (temperature, radiation) and nutrients (nitrogen and phosphorus) influence stoichiometric variation. We find that plant stoichiometry in terrestrial and freshwater ecosystems is more strongly associated with environmental gradients, particularly nitrogen deposition, than animal stoichiometry. Contrary to expectations, temperature, radiation, and labile P show limited global effects. Latitudinal patterns in stoichiometry are more closely associated with species turnover rather than intraspecific variation. Given the strong links between stoichiometry and organismal performance, these findings underscore the need to predict the ecological consequences of anthropogenic disruption to global biogeochemical cycles. Organisms vary in their nitrogen and phosphorus content, shaping ecological and evolutionary processes. This study shows that nitrogen deposition is a consistent global factor associated with plant and animal stoichiometry.

Understanding the factors shaping trophic niche breadth is crucial for predicting species interactions, community assembly, and ecological responses to environmental change. Several hypotheses have been proposed to explain global variation in species' trophic niches, but empirical tests are limited. Here, we used stable isotope analysis (δ13C and δ15N) to quantify trophic niche breadth of 541 fish populations (358 species, 82 families) from freshwater ecosystems encompassing diverse environmental conditions and six biogeographic regions. Fourteen hypotheses relating niche breadth to environmental factors, traits, and sampling scale were tested. Fish isospaces were broader in regions with warmer temperatures, higher humidity, and precipitation variability, suggesting that more productive, diverse, and seasonal ecosystems are associated with broader trophic niches. Conversely, isospace size declined with increasing basin fish richness, which may reflect the role of competitive interactions. Within-population variation in body size was strongly and positively associated with isospace size, indicating ontogenetic dietary shifts. Fish with truncate-rounded fins had broader isospaces than those with forked-lunate fins, likely reflecting differences in foraging behavior and movement. Primary consumers had larger isospaces than intermediate and top consumers. Predators showed patterns similar to those across all trophic guilds, but non-predators differed in relation to solar radiation, richness, body size, and fin shape. Isospace size increased with the number of sampled individuals, habitats and years surveyed. Although isospace patterns have well-documented limitations as trophic ecology metrics, our findings nonetheless conform with several longstanding hypotheses for trophic niche variation and stimulate new ideas about environmental and biological drivers of niche breadth.

Understanding the mechanisms driving parallel evolution across species and populations is fundamental to evolutionary biology. We investigated the parallel phenotypic divergence of trophic morphology in response to predation pressure in two recently described congeneric species of poeciliid fish, Phalloceros harpagos and Phalloceros anisophallos. By comparing populations from high and low predation environments with similar environmental characteristics, we aimed to isolate the effect of predation on trophic traits while controlling the effect of other sources of environmental variation. We found that populations experiencing high predation pressure had shorter guts, which is indicative of a more carnivorous diet, compared to populations in low predation environments. This parallel divergence in trophic morphology suggests that predation indirectly influences per-capita resource availability, driving convergent ecological characteristics in different species of Phalloceros. Our study highlights the importance of considering indirect effects of predation on trophic traits and provides insights into the mechanisms underlying parallel phenotypic divergence. This is one of the few field studies that has directly tested parallel phenotypic divergence, within and between species, focusing on one agent of selection and minimizing the confounding effect of other environmental sources of variation.

Length-weight relationships are useful tools for estimating biomass and understanding ecological roles of aquatic species. In this study, we present parameters of these relationships for nine tadpole species, one tadpole family, and a general model for pond tadpoles. Tadpoles in the Atlantic Forest in Brazil were collected using active search, and their length (L in cm) and dry weight (W in g) were measured to estimate the parameters alpha and beta using the equation log10(W)= log10(alpha) + beta log10(L). The parameter beta ranged from 1.38 to 3.41 across species, with r2 values ranging from 0.45 to 0.97, reflecting the substantial morphological variation among tadpole families and species. The coefficients for the general model for pond tadpoles were beta = 2.33 and alpha = 0.019 (r2= 0.71), providing a reliable estimate when species-specific data are unavailable. This is the first study to report length-weight relationships for tropical tadpoles, providing valuable data for estimating tadpole biomass in Atlantic Forest aquatic ecosystems. These relationships enable researchers to rapidly assess tadpole biomass from length measurements alone, facilitating research on their ecological roles and the potential impacts of their decline on aquatic ecosystem functioning in one of the world's most threatened biodiversity hotspots.

The elemental content of life is a key trait shaping ecology and evolution, yet organismal stoichiometry has largely been studied on a case-by-case basis. This limitation has hindered our ability to identify broad patterns and mechanisms across taxa and ecosystems. To address this, we present StoichLife, a global dataset of 28,049 records from 5,876 species spanning terrestrial, freshwater, and marine realms. Compiled from published and unpublished sources, StoichLife documents elemental content and stoichiometric ratios (%C, %N, %P, C:N, C:P, and N:P) for individual plants and animals. The dataset is standardized and, where available, includes information on taxonomy, habitat, body mass (for animals), geography, and environmental conditions such as temperature, solar radiation, and nutrient availability. By providing an unprecedented breadth of organismal stoichiometry, StoichLife enables the exploration of global patterns, ecological and evolutionary drivers, and context-dependent variations. This resource advances our understanding of the chemical makeup of life and its responses to environmental change, supporting progress in ecological stoichiometry and related fields.

Metacommunity studies have demonstrated that local macroinvertebrate communities are structured not only by local environmental conditions but also by spatial processes. Effective bioassessment tools should account for spatial processes while doing so with the least amount of cost. In this study, we applied variance partition techniques based on redundancy analysis to assess the performance of three sets of benthic invertebrate metrics in detecting agricultural land-use effects in a SE Brazil rainforest watershed. Macroinvertebrate data were analyzed separately regarding their taxonomic, functional structure and bioindicator metrics developed for the study region. We stipulated that groups of metrics most sensitive to land-use effects should have the highest amount of variance explained by the joint effects of land use and environmental variation, independently of spatial structuring. Statistical analyses were repeated removing rare taxa in order to assess the effects of their inclusion in the responsiveness of each group of metrics. Traditional bioindicator metrics were more responsive to environmental variation associated with agriculture than taxa abundances and functional attributes. Furthermore, a few common taxa drove a high proportion of the variation observed in invertebrate communities, regardless of how invertebrate data were organized. Similar analytic approaches have the potential to be useful in curtailing sorting and identification efforts when developing macroinvertebrate-based biomonitoring protocols, especially in areas where information regarding the taxonomy of benthic communities is still poorly described.

Animal stoichiometry affects fundamental processes ranging from organismal physiology to global element cycles. However, it is unknown whether animal stoichiometry follows predictable scaling relationships with body mass and whether adaptation to life on land or water constrains patterns of elemental allocation. To test both interspecific and intraspecific body-size scaling relationships of the nitrogen (N), phosphorus (P), and N:P content of animals, we used a subset of the StoichLife database encompassing 9,933 individual animals (vertebrates and invertebrates) belonging to 1,543 species spanning 10 orders of magnitude of body size from terrestrial, freshwater, and marine realms. Across species, body mass did not explain much variation in %N and %P composition, although the %P of invertebrates decreased with size. The effects of body size on species elemental content were small in comparison to the effects of taxonomy. Body size was a better predictor of intraspecific than interspecific elemental patterns. Between 42 to 45% in intraspecific stoichiometric variation was explained by body size for 27% of vertebrate species and 35% of invertebrate species. Further, differences between organisms inhabiting aquatic and terrestrial realms were observed only in invertebrate interspecific %N, suggesting that the realm does not play an important role in determining elemental allocation of animals. Based on our analysis of the most comprehensive animal stoichiometry database, we conclude that (i) both body size and realm are relatively weak predictors of animal stoichiometry across taxa, and (ii) body size is a good predictor of intraspecific variation in animal elemental content, which is consistent with tissue-scaling relationships that hold broadly across large groups of animals. This research reveals a lack of general scaling patterns in the elemental content across animals and instead points to a large variation in scaling relationships within and among lineages.### Competing Interest StatementThe authors have declared no competing interest.

Consumers vary in their excretion of nitrogen and phosphorus, altering nutrient cycles and ecosystem function. Traditional mass balance models that focus on dietary and tissue nutrients have poorly explained such variation in excretion. Here, we contrast diet and tissue nutrient models for nutrient excretion with predation risk, an often overlooked factor, using the Trinidadian guppy (Poecilia reticulata) as our model system. We surveyed guppies at 12 sites spread across two streams with parallel gradients in food quality and predation risk. At each site, we assessed guppy diet, tissue nitrogen (N), and phosphorus (P) content, and N and P excretion. Predation risk best explained guppy excretion, especially P: guppies excreted less in sites with a dominant predator, while traditional models for excretion rate based on diet quality and tissue nutrients failed to explain it. Guppy tissue N (but not P) most closely correlated with guppy diet quality, showing evidence for flexible homeostasis. Our work extends previous laboratory studies’ results to natural streams and shows that predation risk alters feeding behavior and physiology, driving substantial variation in guppy nutrient, particularly P, excretion rates. We suggest that predation risk is an important factor determining nutrient excretion variation, warranting further attention. Our results also show that tissue nutrients and excretion nutrients are decoupled.

Our study aims to investigate the longitudinal effects of two land-cover transitions on the periphytic algal community. We utilized datasets from three different studies conducted over a 5-year interval in a tropical headwater stream. The studied stream traverses two abrupt adjacent transitions from an upstream forest to a pasture and back to a downstream forest remnant. We performed a high-spatial resolution sampling and used generalized additive models (GAMs) to capture the non-linear gradient response of algal metrics to distance from land-cover transitions. Algal biomass presented a lagged response to increased light availability along the pasture section and decreased along a shorter distance in the downstream forest. Most algal metrics presented a lagged response to transitions, with chlorophyll-a taking up to 375 m to reach the maximum values inside the pasture and up to 300 m to return to reference conditions inside the downstream forest. In the downstream forested section, diatom richness and abundance were similar to the upstream forested section but did not return to reference conditions. The results were consistent across years. Our results indicate that, while riparian forest remnants can play an important role in buffering impacts related to land-cover changes in low order streams, both the magnitude and directionality of these effects might be influenced by longitudinal effects caused by the flow of water. Riparian forest remnants can have a longitudinal effect in stream conditions, influencing environmental characteristics even over non-forested reaches, to where the forest conditions can be propagated downstream by the flow of water.

The elucidation of mechanisms responsible for the reproductive isolation of species is a fundamental part of speciation research. South American poeciliid fishes in the genus Phalloceros represent a promising system in which to study the evolution of reproductive barriers between closely related species. Phalloceros are often found in sympatry with non-sister congeners, and most such species pairs have morphologically divergent female and male genitalia. In recent studies, it has been hypothesized that mismatched genitalia between co-occurring Phalloceros species might act as mechanical barriers to prevent hybridization and might help to explain the diversification of this group. However, this idea has not yet been evaluated empirically with genetic data. Here, we tested this hypothesis using morphological data in conjunction with mitochondrial and nuclear DNA sequence data. Our study focused on Phalloceros anisophallos and Phalloceros leptokeras, two non-sister species that have mismatched genitalia and that occur together in at least four rivers in south-eastern Brazil. Despite the prevalence of hybridization between closely related non-sister species of animals, especially fish, our phylogenetically-based results detected no evidence of mitonuclear discordance and (hence historical hybridization) between the two focal species. Our findings are therefore consistent with the hypothesis that mismatched genitalia prevent hybridization between sympatric species of Phalloceros fishes.

Worldwide, parenthood remains a major driver for the reduced participation of women in the job market, where discrimination stems from people's biases against mothers, based on stereotypes and misconceptions surrounding the vision of motherhood in our society. In academia, parenthood may be perceived as negatively affecting scientists' commitment and dedication, especially women's. We conducted a survey amongst Brazilian scientists and found that mothers self-reported a higher prevalence of negative bias in their workplace when compared to fathers. The perception of a negative bias was influenced by gender and career status, but not by race, scientific field or number of children. Regarding intersections, mothers with less than 15 years of hiring reported having suffered a higher rate of negative bias against themselves. We discuss implications of these results and suggest how this negative bias should be addressed in order to promote an equitable environment that does not harm women in science.

The length-weight relationship parameter is important for obtaining fish weight and biomass data with relevant implications about species role on ecosystem functioning. Here we report the length-weight relationship (LWR) for 24 fish species from three streams located in the Atlantic Forest in the Rio de Janeiro State, Brazil. Fish were collected with electrofishing and standard length (cm) and wet weight (g) were measured to obtain the a and b parameters of the Log (W) = Log (a) + b Log (SL) equation. Length-weight relationships for seven out of 24 species (Hypostomus punctatus, Deuterodon taeniatus, Deuterodon hastatus, Deutorodon janeiroensis, Characidium vidali, Characidium interruptum and Rineloricaria zawadiskii) are reported for the first time. The length-weight relationships reported here contribute to the database that can support fish diversity conservation, fisheries management plans and studies on fish biology.

The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications.

Frontiers in Ecology and the EnvironmentVolume 20, Issue 6 p. 343-344 Write Back Open Access perpetuates differences between higher- and lower-income countries Pilar Santidrián Tomillo, Corresponding Author Pilar Santidrián Tomillo psantidrian@imedea.uib-csic.es Animal Demography and Ecology Unit, Institut Mediterrani d’Estudis Avançats, Esporles, Spain The Leatherback Trust, Goldring-Gund Marine Biology Station, Playa Grande, Costa Rica*E-mail: psantidrian@imedea.uib-csic.esSearch for more papers by this authorEugenia Zandonà, Eugenia Zandonà Departamento de Ecologia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, BrazilSearch for more papers by this authorJuan Pablo Iñamagua, Juan Pablo Iñamagua Facultad de Ciencias Agropecuarias y Departamento de Recursos Hídricos y Ciencias Ambientales, Universidad de Cuenca, Cuenca, EcuadorSearch for more papers by this authorAna Payo-Payo, Ana Payo-Payo School of Biological Sciences, University of Aberdeen, Aberdeen, UKSearch for more papers by this author Pilar Santidrián Tomillo, Corresponding Author Pilar Santidrián Tomillo psantidrian@imedea.uib-csic.es Animal Demography and Ecology Unit, Institut Mediterrani d’Estudis Avançats, Esporles, Spain The Leatherback Trust, Goldring-Gund Marine Biology Station, Playa Grande, Costa Rica*E-mail: psantidrian@imedea.uib-csic.esSearch for more papers by this authorEugenia Zandonà, Eugenia Zandonà Departamento de Ecologia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, BrazilSearch for more papers by this authorJuan Pablo Iñamagua, Juan Pablo Iñamagua Facultad de Ciencias Agropecuarias y Departamento de Recursos Hídricos y Ciencias Ambientales, Universidad de Cuenca, Cuenca, EcuadorSearch for more papers by this authorAna Payo-Payo, Ana Payo-Payo School of Biological Sciences, University of Aberdeen, Aberdeen, UKSearch for more papers by this author First published: 01 August 2022 https://doi.org/10.1002/fee.2538Citations: 1Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume20, Issue6August 2022Pages 343-344 RelatedInformation

Discussions of the factors regulating nutrient recycling by consumers have focused on predictions from Ecological Stoichiometry (ES) and the Metabolic Theory of Ecology (MTE). ES posits that imbalances between the composition of an animal’s body tissues and its diet should determine its nutrient excretion rates, whereas the MTE predicts that excretion should directly reflect metabolic activity arising from body size and temperature. Each framework has been supported by data, but they are rarely tested together. In this study, we measured excretion rates of nitrogen (NH4), phosphorus (SRP) and N:P excretion ratio, body N:P stoichiometry, body size, and temperature for 12 species of fish from an Atlantic rainforest stream in Brazil. We fitted 8 competing models reflecting different combinations of ES (body N:P, armor classification, diet group) and MTE (body size, temperature) variables. For both N and P excretion, as well as excreted N:P ratio, only body size was included in the best model, and interspecific differences in size-scaling were greater for N than for P. Fitted size scaling coefficients were lower than the MTE prediction of 0.75 for both N (0.59, 95% CI = 0.45, 0.73) and P (0.56, 95% CI = 0.40, 0.77). There was only weak evidence that body armor in 3 of 12 species led to more retention of P, and there was no discernable effect of diet group, body N:P, or water temperature. We conclude that differences in nutrient excretion among species within a shared environment primarily reflect contrasts in metabolic rates arising from body size, rather than disparities between consumer and resource stoichiometry. Our findings align with those from other ecosystems and synthesis across aquatic taxa, expanding support for the MTE as the primary framework for predicting nutrient excretion rates. Key words: ecological stoichiometry, metabolic ecology, animals, nitrogen, phosphorus, freshwater.