Eutrophication has become one of the most widespread anthropogenic forces impacting freshwater biological diversity. One potentially important mechanism driving biodiversity changes in response to eutrophication is alteration seasonal patterns succession, particularly among species with short, synchronous, life cycles. We tested hypothesis that reduces seasonally driven variation assemblages by focusing on an understudied aspect biodiversity: temporal beta diversity (βt ). estimated effect...

Coupled production between algae and bacteria in stream epilithon was assessed along a nutrient-enrichment gradient 8 Texas streams with open canopies. Photosynthesis (PS) bacterial biomass (BBP) were measured simultaneously using dual-label radioassay (14C-HCO3– uptake 3H-L-leucine incorporation into protein) on multiple samples within reach. PS BBP after light (1200–1500 μmol m−2 s−1) dark incubations. The degree of coupled estimated as the covariation (i.e., correlation or covariance)...

C, N, and P content were measured across the ontogeny of lotic aquatic insects representing a diversity life-history characteristics. The relationship between individual mass nutrient was used to show ontogenetic patterns by species. Species analyzed for C N exhibited quasihomeostatic pattern ontogeny. Percent %N varied among taxa irrespective ontogeny, with %C ranging from 47.4 56.2% 9.6 11.6%. also species but declined nonlinearly best represented power function. >7% in 1st-instar Tabanus...

Climatological influences on site-specific ecohydrology are particularly germane in semiarid regions where instream flows strongly influenced by effluent discharges. Because many traditional and emerging aquatic contaminants, such as pharmaceuticals, ionizable, we examined diel surface water pH patterns (i.e., change over a 24-h period) at 23 wadeable streams central Texas, USA, representing gradient of nutrient enrichment during consecutive summers 2006 2007. The years our study were...

The authors performed a multiple-pulsed atrazine experiment to measure responses of autotrophic endpoints in outdoor stream mesocosms. was designed synthetically simulate worst-case chemographs from streams agricultural catchments achieve 60-d mean concentrations 0 μg/L (control), 10 μg/L, 20 and 30 μg/L. dosed triplicate with pulses 50 100 150 for 4 d, followed by 7 d without dosing. This 11-d cycle occurred 3 times, recovery (untreated) period day 34 60. Mean ± standard error were 0.07...

Grass litter can be a dominant detritus type in many streams. However, use of this C source stream food webs often is viewed as insignificant because its relatively slow breakdown rates and low nutritional quality. We deployed leaf packs containing senesced bluejoint grass (Calamagrostis canadensis) across natural nutrient gradient 6 salmon-rearing headwater streams on the lower Kenai Peninsula, Alaska. hypothesized that litter-colonizing microbes would dissolved nutrients enhance rates,...

Abstract Nutrient over‐enrichment increasingly threatens global water resources. Stressor‐response studies specifically designed to identify levels of nutrients strongly associated with undesirable ecological conditions are needed inform numeric nutrient criteria that protect inland waters. Diatoms important components aquatic life, which support higher trophic and sensitive enrichment. We tested a framework relies on stressor‐response modelling phosphorus (P) enrichment stream diatom...

We used dual-isotope mixing models (δ13C/δ15N and δ2H/δ15N) in a Bayesian framework to partition allochthonous autochthonous energy sources for salmonids 2 headwater streams the Kenai Lowlands, Alaska (USA). Our 1st objective was estimate production base juvenile coho salmon (Oncorhynchus kisutch) Dolly Varden (Salvelinus malma). hypothesized that consumers would be reliant on both (filamentous algae periphyton) sources, but dominate because of open canopy lower-quality litter inputs...

Wastewater-based epidemiology (WBE) provides an early warning and trend analysis approach for determining the presence of COVID-19 in a community complements clinical testing assessing population level, even as viral loads fluctuate. Here, we evaluate combinations two wastewater concentration methods (i.e., ultrafiltration composite supernatant-solid), four pre-RNA extraction modifications, three nucleic acid kits using different sampling locations. These consisted quarantine facility...

The effects of co-occurring nutrient and contaminant stressors are very likely to interact in aquatic systems, particularly at the level primary producers. Site-specific nitrogen (N) phosphorus (P) concentrations often much lower differ relative availability than those used nutrient-saturated laboratory assays for plants, which can introduce uncertainty prospective ecological hazard risk assessments. Because triclosan, an antimicrobial agent included personal care products, potentially...

We contrasted the carbon, nitrogen, and phosphorus (C: N: P) stoichiometry of Caenis spp. (Ephemeroptera:Caenidae) nymphs from 2 stream reaches differing in P enrichment. also estimated growth rates reared on algae different content across four development classes a laboratory experiment. C: N ratios field-collected exhibited variable responses between sites whereas showed clear unimodal response, increasing II through IV but then declining sharply class V (nymphs nearing eclosion) at both...

Conservation and management of headwater streams amid rapid global change require an understanding the spatial environmental factors that drive species distributions associated ecosystem processes. We used a hierarchical analytical framework to model effects catchment-scale topography wetland geomorphic classes on stream physical habitat, chemistry, macroinvertebrate fish communities in 30 across Kenai Lowlands, southcentral Alaska, USA. identified 135 taxa, 122 which were aquatic insects,...

Excessive nutrient inputs and grazers can influence biomass elemental composition of primary producers in freshwater ecosystems. How interactions between enrichment grazing fish alter benthic habitats through effects on periphyton autotrophy, biomass, has been studied rarely. We compared the by central stonerollers (Campostoma anomalum) autotrophic total sediment mass, C, N, P stoichiometry 12 flow-through stream mesocosms randomly assigned to 1 3 different PO4-P concentrations (control: 8...

Abstract Comprehension of basic stream ecosystem function relies on an understanding aquatic–terrestrial linkages. One major component such linkages is the incorporation landscape‐derived energy and nutrients into aquatic food web via microbes. In many boreal streams, wetlands alder are known to be primary sources dissolved organic carbon ( DOC ) inorganic nitrogen DIN ), respectively. To simulate influence highly labile portion wetland‐derived subsidies microbial production processes in a...

Fish-mediated nutrient recycling influences dynamics in stream ecosystems, but its consequences for smaller-scale microbial processes benthic habitats are not well understood. We quantified the effect of by grazing fish, Campostoma anomalum, on downstream periphyton 12 flow-through mesocosms. compared ratios and algal biomass (as chlorophyll a [chl a]) between tiles upstream enclosures with without fish to measure nutrient-cycling effects streams low (11) high (177) surface-water dissolved...

Freshwater ecosystems are exposed to engineered nanoparticles through municipal and industrial wastewater-effluent discharges agricultural nonpoint source runoff. Because previous work has shown that from these sources can accumulate in freshwater algal assemblages, we hypothesized may affect the biology of primary consumers by altering processing two critical nutrients associated with growth survivorship, nitrogen phosphorus. We tested this hypothesis measuring excretion rates phosphorus...

Alder (Alnus spp.) is a woody plant with bacterial symbionts that fix atmospheric N2 into bioavailable N. We studied 12 North American boreal headwater streams spanning steep gradient of catchment alder cover (0–27%) to test the hypothesis increasing inputs inorganic N associated would reduce or eliminate in-stream benthic fixation. measured fixation rates, chlorophyll a, and ash-free dry mass (AFDM) periphyton in early (May) late (August) summer 2011. Dissolved (DIN) concentrations,...