Implications of species addition and decline for nutrient dynamics in freshwaters.

In terrestrial and aquatic ecosystems, organisms directly affect nutrient storage and cycling by sequestering nutrients via growth and remineralizing nutrients via excretion and egestion. Therefore, species introductions and extirpations can profoundly affect nutrient storage and remineralization rates, and present a challenge for conserving ecosystem function in fresh waters. The literature of consumer-driven nutrient dynamics is growing rapidly, but studies of consumer effects on nutrient storage and remineralization across species and among ecosystems are limited. We compared the effects of 3 grazing taxa, nonnative armored catfish in Mexican streams, native mussels in Oklahoma streams, and native tadpoles in Panamanian streams, on nutrient storage and remineralization. We examined interactions among organismal stoichiometry and biomass, nutrient storage, remineralization rates, and ecosystem size across these 3 groups following species decline (tadpoles and mussels) or introduction (armored catfish) to gain a better understanding of organism-specific effects on nutrient dynamics among freshwater ecosystems. Collectively, our results suggest that the ecosystem-level effect of consumer-driven nutrient dynamics is strongly influenced by environmental variables and is taxon specific. Major changes in biomass of stoichiometrically distinctive organisms can lead to subsequent changes in the flux and storage of elements in an ecosystem, but the overall effect of aquatic animals on nutrient dynamics also is determined by discharge and nutrient-limitation patterns in streams and rivers

Thermal stress analysis of a directionally solidified Al-1 wt%Ni alloy casting

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)As the development of thermal stresses is closely related to the cooling history of castings, it is essential to consider the thermal evolution from the molten state up to the solid condition at the room temperature. This work develops a thermal analysis solution applying the ANSYS software (ANSYS Inc., Southpointe, PA, USA). As a result, an integrated system of thermal stress analysis during the solidification process was developed. A solidification experiment was carried out in order to directionally solidify an Al-1wt%Ni hypoeutectic alloy casting under upward unsteady-state heat flow conditions. The experimental cooling curves were compared with the temperature fields provided by ANSYS, and a good agreement has been observed. The thermal stresses were determined in the solid zone of the directionally solidified casting. (C) 2010 Elsevier B.V. All rights reserved.4610889895Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FAEPEX-UNICAMPFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Emerging towards a more diverse community of freshwater scientists, using the 4DEE framework

Presented at the Ecological Society of America Virtual Annual Meeting

Can’t stop, won’t stop – Continuing the journey to full inclusivity in freshwater science with the Emerge Program

Presented at the Society for Freshwater Science Annual Meeting

A global database of nitrogen and phosphorous excretion rates of aquatic animals

Animals can be important in modulating ecosystem-level nutrient cycling, although their importance varies greatly among species and ecosystems. Nutrient cycling rates of individual animals represent valuable data for testing the predictions of important frameworks such as the Metabolic Theory of Ecology (MTE) and ecological stoichiometry (ES). They also represent an important set of functional traits that may reflect both environmental and phylogenetic influences. Over the past two decades, studies of animal-mediated nutrient cycling have increased dramatically, especially in aquatic ecosystems. Here we present a global compilation of aquatic animal nutrient excretion rates. The dataset includes 10,534 observations from freshwater and marine animals of N and/or P excretion rates. These observations represent 491 species, including most aquatic phyla. Coverage varies greatly among phyla and other taxonomic levels. The dataset includes information on animal body size, ambient temperature, taxonomic affiliations, and animal body N:P. This data set was used to test predictions of MTE and ES, as described in Vanni and McIntyre (2016; Ecology DOI: 10.1002/ecy.1582). © 2017 Ecological Society of Americ