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1. Fish feces reveal diverse nutrient sources for coral reefs

   https://doi.org/10.1002/ecy.4119  

   Van_Wert, Jacey_C; Ezzat, Leïla; Munsterman, Katrina_S; Landfield, Kaitlyn; Schiettekatte, Nina_M_D; Parravicini, Valeriano; Casey, Jordan_M; Brandl, Simon_J; Burkepile, Deron_E; Eliason, Erika_J (June 2023, Ecology)

   Abstract Consumers mediate nutrient cycling through excretion and egestion across most ecosystems. In nutrient‐poor tropical waters such as coral reefs, nutrient cycling is critical for maintaining productivity. While the cycling of fish‐derived inorganic nutrients via excretion has been extensively investigated, the role of egestion for nutrient cycling has remained poorly explored. We sampled the fecal contents of 570 individual fishes across 40 species, representing six dominant trophic guilds of coral reef fishes in Moorea, French Polynesia. We measured fecal macro‐ (proteins, carbohydrates, lipids) and micro‐ (calcium, copper, iron, magnesium, manganese, zinc) nutrients and compared the fecal nutrient quantity and quality across trophic guilds, taxa, and body size. Macro‐ and micronutrient concentrations in fish feces varied markedly across species. Genera and trophic guild best predicted fecal nutrient concentrations. In addition, nutrient composition in feces was unique among species within both trophic guilds (herbivores and corallivores) and genera (AcanthurusandChaetodon). Particularly, certain coral reef fishes (e.g.,Thalassoma hardwicke,Chromis xanthura,Chaetodon pelewensisandAcanthurus pyroferus) harbored relatively high concentrations of micronutrients (e.g., Mn, Mg, Zn and Fe, respectively) that are known to contribute to ocean productivity and positively impact coral physiological performances. Given the nutrient‐rich profiles across reef fish feces, conserving holistic reef fish communities ensures the availability of nutritional pools on coral reefs. We therefore suggest that better integration of consumer egestion dynamics into food web models and ecosystem‐scale processes will facilitate an improved understanding of coral reef functioning. 

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2. Disentangling the role of ectomycorrhizal fungi in plant nutrient acquisition along a Zn gradient using X-ray imaging

   https://doi.org/10.1016/j.scitotenv.2021.149481  

   Zhang, Kaile; Tappero, Ryan; Ruytinx, Joske; Branco, Sara; Liao, Hui-Ling (December 2021, Science of the total environment)

   Zinc (Zn) is a plant essential micronutrient involved in a wide range of cellular processes. Ectomycorrhizal fungi (EMF) are known to play a critical role in regulating plant Zn status. However, how EMF control uptake and translocation of Zn and other nutrients in plant roots under different Zn conditions is not well known. Using X-ray fluorescence imaging, we found the EMF species Suillus luteus increased pine root Zn acquisition under low Zn concentrations and reduced its accumulation under higher Zn levels. By contrast, non-mycorrhizal pine roots exposed to high Zn indiscriminately take up and translocate Zn to root tissues, leading to Zn stress. Regardless of S. luteus inoculation, the absorption pattern of Ca and Cu was similar to Zn. Compared to Ca and Cu, effects of S. luteus on Fe acquisition were more marked, leading to a negative association between Zn addition and Fe concentration within EMF roots. Besides, higher nutrient accumulation in the fungal sheath, compared to hyphae inhabiting between intercellular space of cortex cells, implies the fungal sheath serves as a barrier to regulate nutrient transportation into fungal Hartig net. Our results demonstrate the crucial roles EMF play in plant nutrient uptake and how fungal partners ameliorate soil chemical conditions either by increasing or decreasing element uptake. 

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3. Transition metal-doped MgO nanoparticles for nutrient recycling: an alternate Mg source for struvite synthesis from wastewater

   https://doi.org/10.1039/D0EN00660B  

   Silva, Manoj; Murzin, Vadim; Zhang, Lihua; Baltrus, John; Baltrusaitis, Jonas (November 2020, Environmental Science: Nano)

   null (Ed.)

   Nutrient nitrogen (N) and phosphorus (P) recovery from wastewater is an important challenge for enhanced environmental sustainability. Herein we report the synthesis and properties of mesoporous MgO nanoparticles doped with copper (Cu), iron (Fe), and zinc (Zn) as an alternative low-solubility high-abundance magnesium (Mg) source for crystalline struvite precipitation from nutrient-laden wastewater. Undoped MgO was shown to have the fastest phosphate (PO 4 3− ) adsorption kinetics with a k 2 value of 0.9 g g −1 min −1 at room temperature. The corresponding rate constant decreased for Cu–MgO (0.175 g g −1 min −1 ), Zn–MgO (0.145 g g −1 min −1 ), and Fe–MgO (0.02 g g −1 min −1 ). Undoped MgO resulted in the highest PO 4 3− removal at 94%, while Cu–MgO, Fe–MgO, and Zn–MgO resulted in 90%, 66% and 66%, respectively, under equivalent reaction conditions. All dopants resulted in the production of struvite as the main product with the incorporation of the transition metals into the struvite crystal lattice. X-ray absorption spectroscopy (XAS) showed that the majority of the Cu, Fe, and Zn were primarily in the +2, +3, and +2 oxidation states, respectively. XAS also showed that the Cu atoms exist in elongated octahedral coordination, while Fe was shown to be in octahedral coordination. Zn was shown to be in a complex disordered environment with octahedral sites coexisting with the majority of the tetrahedral sites. Finally, X-ray photoelectron spectroscopy data suggest a two-fold struvite surface enrichment with dopant metals, with Cu exhibiting an interesting new local binding structure. The dopant concentrations utilized were consistent with those found in natural Mg minerals, suggesting that (a) utilizing natural mineral periclase as the Mg source for struvite production can result in struvite formation, albeit at the expense of the reaction kinetics and overall yields, while also (b) supplying essential micronutrients, such as Zn and Cu, necessary for balanced nutrient uptake. 

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4. Productivity and Nutrient Quality of Lemna minor as Affected by Microbiome, CO2 Level, and Nutrient Supply

   https://doi.org/10.3390/stresses3010007  

   Zenir, Madeleine C.; López-Pozo, Marina; Polutchko, Stephanie K.; Stewart, Jared J.; Adams, William W.; Escobar, Adam; Demmig-Adams, Barbara (March 2023, Stresses)

   Rising atmospheric carbon dioxide (CO2) levels can impact plant photosynthesis and productivity and threaten food security, especially when combined with additional environmental stressors. This study addresses the effects of elevated CO2 in combination with low nutrient supply on Lemna minor (common duckweed). We quantified plant growth rate and nutritional quality (protein content) and evaluated whether any adverse effects of elevated CO2, low nutrients, or the combination of the two could be mitigated by plant-microbe interaction. Plants were grown under controlled conditions and were either uninoculated or inoculated with microorganisms from a local pond that supported L. minor populations. Under low nutrients in combination with high CO2, growth (plant area expansion rate) decreased and biomass accumulation increased, albeit with lower nutritional quality (lower percentage of protein per plant biomass). Inoculation with plant-associated microorganisms restored area expansion rate and further stimulated biomass accumulation while supporting a high protein-to-biomass ratio and, thus, a high nutritional quality. These findings indicate that plant-microbe interaction can support a higher nutritional quality of plant biomass under elevated atmospheric CO2 levels, an important finding for both human and non-human consumers during a time of rapid environmental change. 

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5. Time series of total metal and nutrient loads into Falling Creek Reservoir in southwestern Virginia, USA from 2019-2024

   https://doi.org/10.6073/pasta/5a77855d308043f20f953d258b570fb7  

   Schreiber, Madeline E; Bauer, Carly E; Wood, Cecelia E; Breef-Pilz, Adrienne; Hammond, Nicholas W; Iannuci, Frances; Woelmer, Whitney M; Howard, Dexter W; Wander, Heather L; Niederlehner, Barbara R (June 2025, Environmental Data Initiative)

   Metal and nutrient loads were calculated from 2019-2024 from the inflow stream to Falling Creek Reservoir (FCR), a drinking water reservoir located in Vinton, Virginia, USA. The reservoir is owned and operated by the Western Virginia Water Authority and is managed as a secondary drinking-water source for the city of Roanoke, VA. Only Fe, Mn, and nutrients (TN and TP) were analyzed and calculated in 2019. The full suite of metals (Li, Na, Mg, Al, K, Ca, Fe, Mn, Cu, Sr, Ba) and nutrients were analyzed from 2020-2024. The loads that were collected using an ISCO automated sampler located at the main inflow tributary to FCR. Sampling frequency was approximately fortnightly from spring to fall (March - November). Load calculations were performed using the calculated cumulative flow over the sampling period from the ISCO and the analyzed total metal and nutrient concentrations. Please note we are publishing this data package before the nutrient samples have been analyzed, but will be included in later versions. 

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