The effects of salinity and N:P on N-rich toxins by both an N-fixing and non-N-fixing cyanobacteria.

Freshwater ecosystems are experiencing increased salinization. Adaptive management of harmful algal blooms (HABs) contribute to eutrophication/salinization interactions through the hydrologic transport of blooms to coastal environments. We examined how nutrients and salinity interact to affect growth, elemental composition, and cyanotoxin production/release in two common HAB genera. Microcystis aeruginosa (non-nitrogen (N)-fixer and microcystin-LR producer; MC-LR) and Aphanizomenon flos-aquae (N-fixer and cylindrospermopsin producer; CYN) were grown in N:phosphorus (N:P) 4 and 50 (by atom) for 21 and 33 days, respectively, then dosed with a salinity gradient (0 - 10.5 g L-1). Both total MC-LR and CYN were correlated with particulate N. We found Microcystis MC-LR production and release was affected by salinity only in the N:P 50 treatment. However, Aphanizomenon CYN production and release was affected by salinity regardless of N availability. Our results highlight how cyanotoxin production and release across the freshwater - marine continuum are controlled by eco-physiological differences between N-acquisition traits.

Diazotrophy modulates cyanobacteria stoichiometry through functional traits that determine bloom magnitude and toxin production.

Harmful cyanobacterial blooms are an increasing threat to water quality. The interactions between two eco-physiological functional traits of cyanobacteria, diazotrophy (nitrogen (N)-fixation) and N-rich cyanotoxin synthesis, have never been examined in a stoichiometric explicit manner. We explored how a gradient of resource N:phosphorus (P) affects the biomass, N, P stoichiometry, light-harvesting pigments, and cylindrospermopsin production in a N-fixing cyanobacterium, Aphanizomenon. Low N:P Aphanizomenon cultures produced the same biomass as populations grown in high N:P cultures. The biomass accumulation determined by carbon, indicated low N:P Aphanizomenon cultures did not have a N-fixation growth tradeoff, in contrast to some other diazotrophs that maintain stoichiometric N homeostasis at the expense of growth. However, N-fixing Aphanizomenon populations produced less particulate cylindrospermopsin and had undetectable dissolved cylindrospermopsin compared to non-N-fixing populations. The pattern of low to high cyanotoxin cell quotas across an N:P gradient in the diazotrophic cylindrospermopsin producer is similar to the cyanotoxin cell quota response in non-diazotrophic cyanobacteria. We suggest that diazotrophic cyanobacteria may be characterized into two broad functional groups, the N-storage-strategists and the growth-strategists, which use N-fixation differently and may determine patterns of bloom magnitude and toxin production in nature.

Sustaining University Operations During the COVID-19 Pandemic.

Colleges and universities around the world engaged diverse strategies during the COVID-19 pandemic. Baylor University, a community of ˜22,700 individuals, was 1 of the institutions which resumed and sustained operations. The key strategy was establishment of multidisciplinary teams to develop mitigation strategies and priority areas for action. This population-based team approach along with implementation of a "Swiss Cheese" risk mitigation model allowed small clusters to be rapidly addressed through testing, surveillance, tracing, isolation, and quarantine. These efforts were supported by health protocols including face coverings, social distancing, and compliance monitoring. As a result, activities were sustained from August 1 to December 8, 2020. There were 62,970 COVID-19 tests conducted with 1435 people testing positive for a positivity rate of 2.28%. A total of 1670 COVID-19 cases were identified with 235 self-reports. The mean number of tests per week was 3500 with approximately 80 of these positive (11/d). More than 60 student tracers were trained with over 120 personnel available to contact trace, at a ratio of 1 per 400 university members. The successes and lessons learned provide a framework and pathway for similar institutions to mitigate the ongoing impacts of COVID-19 and sustain operations during a global pandemic.

Comparative Analysis of RNA-Extraction Approaches and Associated Influences on RT-qPCR of the SARS-CoV-2 RNA in a University Residence Hall and Quarantine Location.

Wastewater-based epidemiology (WBE) provides an early warning and trend analysis approach for determining the presence of COVID-19 in a community and complements clinical testing in assessing the population level, even as viral loads fluctuate. Here, we evaluate combinations of two wastewater concentration methods (i.e., ultrafiltration and composite supernatant-solid), four pre-RNA extraction modifications, and three nucleic acid extraction kits using two different wastewater sampling locations. These consisted of a quarantine facility containing clinically confirmed COVID-19-positive inhabitants and a university residence hall. Of the combinations examined, composite supernatant-solid with pre-RNA extraction consisting of water concentration and RNA/DNA shield performed the best in terms of speed and sensitivity. Further, of the three nucleic acid extraction kits examined, the most variability was associated with the Qiagen kit. Focusing on the quarantine facility, viral concentrations measured in wastewater were generally significantly related to positive clinical cases, with the relationship dependent on method, modification, kit, target, and normalization, although results were variable-dependent on individual time points (Kendall's Tau-b (τ) = 0.17 to 0.6) or cumulatively (Kendall's Tau-b (τ) = -0.048 to 1). These observations can support laboratories establishing protocols to perform wastewater surveillance and monitoring efforts for COVID-19.

Differential influences of (±) anatoxin-a on photolocomotor behavior and gene transcription in larval zebrafish and fathead minnows.

BACKGROUND: Though anatoxin-a (antx-a) is a globally important cyanobacterial neurotoxin in inland waters, information on sublethal toxicological responses of aquatic organisms is limited. We examined influences of (±) antx-a (11-3490 µg/L) on photolocomotor behavioral responses and gene transcription associated with neurotoxicity, oxidative stress and hepatotoxicity, in two of the most common alternative vertebrate and fish models, Danio rerio (zebrafish) and Pimephales promelas (fathead minnow). We selected environmentally relevant treatment levels from probabilistic exposure distributions, employed standardized experimental designs, and analytically verified treatment levels using isotope-dilution liquid chromatography tandem mass spectrometry. Caffeine was examined as a positive control. RESULTS: Caffeine influences on fish behavior responses were similar to previous studies. Following exposure to (±) antx-a, no significant photolocomotor effects were observed during light and dark transitions for either species. Though zebrafish behavioral responses profiles were not significantly affected by (±) antx-a at the environmentally relevant treatment levels examined, fathead minnow stimulatory behavior was significantly reduced in the 145-1960 µg/L treatment levels. In addition, no significant changes in transcription of target genes were observed in zebrafish; however, elavl3 and sod1 were upregulated and gst and cyp3a126 were significantly downregulated in fathead minnows. CONCLUSION: We observed differential influences of (±) antx-a on swimming behavior and gene transcription in two of the most common larval fish models employed for prospective and retrospective assessment of environmental contaminants and water quality conditions. Sublethal responses of fathead minnows were consistently more sensitive than zebrafish to this neurotoxin at the environmentally relevant concentrations examined. Future studies are needed to understand such interspecies differences, the enantioselective toxicity of this compound, molecular initiation events within adverse outcome pathways, and subsequent individual and population risks for this emerging water quality threat.

Nitrogen form, concentration, and micronutrient availability affect microcystin production in cyanobacterial blooms.

Harmful algal blooms (HABs) are increasing in magnitude, frequency, and duration caused by anthropogenic factors such as eutrophication and altered climatic regimes. While the concentrations and ratios of nitrogen (N) and phosphorus are correlated with bloom biomass and cyanotoxin production, there is less known about how N forms and micronutrients (MN) interact to regulate HABs and cyanotoxin production. Here, we used two separate approaches to examine how N and MN supply affects cyanobacteria biomass and cyanotoxin production. First, we used a Microcystis laboratory culture to examine how N and MN concentration and N form affected the biomass, particulate N, and microcystin-LR concentration and cell quotas. Then, we monitored the N, iron, molybdenum, and total microcystin concentrations from a hypereutrophic reservoir. From this hypereutrophic reservoir, we performed a community HAB bioassay to examine how N and MN addition affected the biomass, particulate N, and microcystin concentration. Microcystis laboratory cultures grown in high urea and MN conditions produced more biomass, particulate N, and had similar C:N stoichiometry, but lower microcystin-LR concentrations and cell quotas when compared to high nitrate and MN conditions. Our community HAB bioassay revealed no interactions between N concentration and MN addition caused by non-limiting MN background concentrations. Biomass, particulate N, and microcystin concentration increased with N addition. The community HAB amended with MN resulted in greater microcystin-LA concentration compared to non-MN amended community HABs. Our results highlight the complexity of how abiotic variables control biomass and cyanotoxin production in both laboratory cultures of Microcystis and community HABs.

Sunlight concurrently reduces Prymnesium parvum elicited acute toxicity to fish and prymnesins.

Prymnesium parvum continues to spread globally, producing harmful algal blooms that release toxins known to cause fish kills. While previous work has identified possible P. parvum toxin(s) (e.g., prymnesins, fatty acids, fatty acid amides) and investigated treatment strategies targeted at minimizing cell abundance, studies examining efficacy of treatment approaches to remove toxins are lacking. To understand influences of sunlight on toxins stability and toxicity to fish, acutely toxic P. parvum cultures were exposed to three light scenarios (lab dark control, field dark, and field light) and then evaluated for acute toxicity to fish and prymnesins abundance. Previous work showed acute toxicity to fathead minnow larvae was ameliorated after 2 h of sunlight exposure, and results observed herein found an identical trend. Acute toxicity disappeared in light exposed filtrate, but filtrate exposed to 35 °C without sunlight remained acutely toxic to fish. Additionally, six prymnesins were identified through high-resolution mass spectrometry and abundance corresponded to acute toxicity levels. Prymnesins were present at the highest level in filtrate that was acutely toxic but diminished in filtrate that was exposed to light and correspondingly ameliorated acute toxicity to fish. These findings suggest prymnesins are responsible for measured acute toxicity and are photo-labile, which represents an important implication for treatment strategies.

Periphyton, bivalves and fish differentially accumulate select pharmaceuticals in effluent-dependent stream mesocosms.

Pharmaceuticals and other ionizable contaminants from municipal wastewater treatment plant effluent can bioaccumulate in fish, particularly in effluent dominated and dependent systems in semi-arid and arid regions. However, invertebrate bioaccumulation of these compounds has been less studied. Using municipal wastewater effluent as source water in outdoor stream mesocosms to simulate effluent-dependent lotic systems, we examined bioaccumulation of several widely-used pharmaceuticals including acetaminophen (nonsteroidal anti-inflamatory), caffeine (stimulant), carbamazepine (anti-epileptic), diltiazem (calcium channel blocker), diphenhydramine (anti-histamine), fluoxetine (anti-depressant), norfluoxetine (anti-depressant metabolite), and sertraline (anti-depressant) in freshwater clams (Corbicula fluminea), periphyton and stoneroller minnows (Campostoma anomalum), a commonly studied grazer in stream ecology, during a replicated outdoor stream mesocosm study at the Baylor Experimental Aquatic Research facility. Target analytes were determined in tissues, source effluent and stream water by isotope dilution LC-MS/MS. After an 8-day uptake period, clams accumulated a number of pharmaceuticals, including acetaminophen, carbamazepine, diltiazem, diphenhydramine, fluoxetine, norfluoxetine and sertraline with maximum concentrations reaching low µg/kg. We observed uptake rates in clams for acetaminophen at 2.8 µg/kg per day, followed by diphenhydramine (1.2 µg/kg per day) and carbamazepine (1.1 µg/kg per day). Caffeine, carbamazepine, diltiazem and diphenhydramine were measured in periphyton. Diphenhydramine was the only compound detected in all matrices, where bioaccumulation factors (BAFs) were elevated in bivalves (1631 ± 589 L/kg), compared to stoneroller minnows (247 ± 84 L/kg) and periphyton (315 ± 116 L/kg). Such BAF variability across multiple biological matrices highlight the need to understand bioaccumulation differences for ionizable contaminants among freshwater biota, including threatened and endangered species (e.g., unionids), commercially important bivalves (e.g., estuarine and marine bivalves), and fish.

Effects of Environmentally Relevant Concentration Exposure Profiles on Polar Organic Chemical Integrative Sampler (POCIS) Sampling Rates.

Polar organic chemical integrative sampler (POCIS) is a passive sampling device that offers many advantages over traditional discrete sampling methods, but quantitative time-weighted average (TWA) concentrations rely heavily on the robustness of sampling rates. The effects of changing chemical concentration exposures on POCIS sampling rates and its ability to operate in an integrative regime were investigated for 12 pesticides across a range of environmentally relevant concentrations. In five independent 21-day experiments, POCIS devices were exposed to these compounds at constant concentrations ranging from 3 to 60 µg/L and multiple pulsed concentrations with maximum peaks ranging from 5 to 150 µg/L (TWA concentrations = 3 to 92 µg/L). For the 21-day exposures to constant and pulsed concentrations, there were no significant differences in the POCIS sampling rates between corresponding TWA concentrations. Similarly, there was no significant effect on POCIS ability to operate in an integrative regime. However, loss of linearity was visible for some replicates when exposed to higher pulsed concentrations over an extended period. Modeling and Freundlich isotherms did not predict sorbent saturation, but the extraction and reconstitution protocol likely contributed to atrazine dissolution and subsequent underestimation of sorbed chemical mass when HLB adsorption exceeded 400 µg.

Pharmaceutical uptake kinetics in rainbow trout: In situ bioaccumulation in an effluent-dominated river influenced by snowmelt.

Whether seasonal instream flow dynamics influence bioaccumulation of pharmaceuticals by fish is not well understood, specifically for urban lotic systems in semi-arid regions when flows are influenced by snowmelt. We examined uptake of select pharmaceuticals in rainbow trout (Oncorhynchus mykiss) caged in situ upstream and at incremental distances downstream (0.1, 1.4, 13 miles) from a municipal effluent discharge to East Canyon Creek in Park City, Utah, USA during summer and fall of 2018. Fish were sampled over 7-d to examine if uptake occurred, and to define uptake kinetics. Water and fish tissues were analyzed via isotope dilution liquid chromatography tandem mass spectrometry. Several pharmaceuticals were consistently detected in water, fish tissue and plasma, including carbamazepine, diphenhydramine, diltiazem, and fluoxetine. Pharmaceutical levels in water ranged up to 151 ng/L for carbamazepine, whereas the effluent tracer sucralose was consistently observed at low µg/L levels. During both summer and fall experiments at each of three downstream locations from effluent discharge, rainbow trout rapidly accumulated these pharmaceuticals; tissue levels reached steady state conditions within 24-96 h. Spatial and temporal differences for pharmaceutical levels in rainbow trout directly corresponded with surface water exposure concentrations, and uptake kinetics for individual pharmaceuticals did not vary among sites or seasons. Such observations are consistent with recent laboratory bioconcentration studies, which collectively indicate inhalational exposure from water governs rapid accumulation of ionizable base pharmaceuticals by fish in inland surface waters.

Suspect and non-target screening of acutely toxic Prymnesium parvum.

Harmful algal blooms (HABs) are increasing in frequency, magnitude, and duration around the world. Prymnesium parvum is a HAB species known to cause massive fish kills, but the toxin(s) it produces contributing to this acute toxicity to fish have not been confirmed. In the present study, a 2 × 2 factorial design was employed to examine influences of salinity (2.4 or 5 ppt) and nutrient limitation (f/2 or f/8) on P. parvum acute toxicity to fish and produced molecules. Acute toxicity (LC50) of these cultures, following a 48-h mortality assay, ranged from 10,213 to 96,816 cells mL-1. Non-targeted analysis was performed using liquid chromatography high-resolution mass spectrometry (LC-HRMS) to investigate compounds contributing to the differential toxicological responses. When P. parvum elicited toxicity to fish, suspect screening confirmed the presence of several prymnesins, and the peak area of PRM-A (3 Cl; prymnesin2aglycone) was significantly (p < 0.05) and positively related to acute toxicity. In addition, a non-targeted approach to highlighting peaks that differ between two chemical fingerprints was developed, termed a relative difference plot, and used to search for peaks co-varying with P. parvum induced acute toxicity to fish. Several peaks were highlighted along with the prymnesins identified through suspect screening when acute toxicity to fish was observed.

Low dissolved oxygen increases uptake of a model calcium channel blocker and alters its effects on adult Pimephales promelas.

Human population growth accompanied with urbanization is urbanizing the water cycle in many regions. Urban watersheds, particularly with limited upstream dilution of effluent discharges, represent worst case scenarios for exposure to multiple environmental stressors, including down the drain chemicals (e.g., pharmaceuticals) and other stressors (e.g., dissolved oxygen (DO)). We recently identified the calcium channel blocker diltiazem (DZM) to accumulate in fish plasma exceeding human therapeutic doses (e.g., Cmin) in coastal estuaries impaired due to nonattainment of DO water quality standards. Thus, we examined whether DO influences DZM uptake by fish, and if changes in DO-dependent upatke alter fish physiological and biochemical responses. Low DO (3.0 mg DO/L) approximately doubled diltiazem uptake in adult fathead minnows relative to normoxic (8.2 mg DO/L) conditions and were associated with significant (p < 0.05) increases in fish ventilation rate at low DO levels. Decreased burst swim performance (Uburst) of adult fathead minnows were significantly (p < 0.05) altered by low versus normal DO levels. DO × DZM studies reduced Uburst by 13-31% from controls, though not significantly (p = 0.06). Physiological responses in fish exposed to DZM alone were minimal; however, in co-exposure with low DO, decreasing trends in Uburst appeared inversely related to plasma lactate levels. Such physiological responses to multiple stressors, when paired with internal tissue concentrations, identify the utility of employing biological read across approaches to identify adverse outcomes of heart medications and potentially other cardiotoxicants impacting fish cardiovascular function across DO gradients.

Effects of suspended sediment on POCIS sampling rates.

Effects of chemical uptake onto polar organic chemical integrative samplers (POCIS) exposed to total suspended solid (TSS) sediment concentrations of 0 and 3600 ppm were investigated for 12 pesticides at constant concentration, temperature, and flow velocity. The effects of sediment exposure on POCIS uptake were negligible for compounds with polyethersulfone-water partition coefficients greater than three (i.e., log KPESW > 3). However, significant effects were observed for 3 of 12 compounds tested, and the maximum effect was an approximate 4-fold increase in sampling rate for the sediment experiment relative to the control. Effects of sediment on the pesticide distribution between polyethersulfone (PES) membranes and Oasis HLB sorbent were also investigated. The fraction of pesticide accumulated on PES membranes was relatively low for most compounds and ranged from 0 to 33%. In contrast, four compounds with higher affinity for PES accumulated preferentially on the membranes (fraction ranging from 64 to 96%), suggesting that a sampling rate derived from the additive contribution of membrane extraction and the more typical extraction of analytes from HLB sorbent would improve the sensitivity of sampling rate estimations for these compounds. However, for these same compounds, the combined sampling rate, Rs (HLB + PES), was considerably more susceptible to a sediment effect than the traditional sampling rate determination, relying solely on extraction from HLB sorbent.

Biological Stoichiometry Regulates Toxin Production in Microcystis aeruginosa (UTEX 2385).

Harmful algal blooms (HABs) are increasing in magnitude, frequency, and duration globally. Even though a limited number of phytoplankton species can be toxic, they are becoming one of the greatest water quality threats to public health and ecosystems due to their intrinsic toxicity to humans and the numerous interacting factors that undermine HAB forecasting. Here, we show that the carbon:nitrogen:phosphorus (C:N:P) stoichiometry of a common toxic phytoplankton species, Microcystis, regulates toxin quotas during blooms through a tradeoff between primary and secondary metabolism. Populations with optimal C:N (< 8) and C:P (< 200) cellular stoichiometry consistently produced more toxins than populations exhibiting stoichiometric plasticity. Phosphorus availability in water exerted a strong control on population biomass and C:P stoichiometry, but N availability exerted a stronger control on toxin quotas by regulating population biomass and C:N:P stoichiometry. Microcystin-LR, like many phytoplankton toxins, is an N-rich secondary metabolite with a C:N stoichiometry that is similar to the optimal growth stoichiometry of Microcystis. Thus, N availability relative to P and light provides a dual regulatory mechanism that controls both biomass production and cellular toxin synthesis. Overall, our results provide a quantitative framework for improving forecasting of toxin production during HABs and compelling support for water quality management that limit both N and P inputs from anthropogenic sources.

Influence of salinity and pH on bioconcentration of ionizable pharmaceuticals by the gulf killifish, Fundulus grandis.

Estuaries routinely receive discharges of contaminants of emerging concern from urban regions. Within these dynamic estuarine systems, salinity and pH can vary across spatial and temporal scales. Our previous research identified bioaccumulation of the calcium channel blocker diltiazem and the antihistamine diphenhydramine in several species of fish residing in multiple urban estuaries along the Gulf of Mexico in Texas, where field-measured observations of diltiazem in fish plasma exceeded human therapeutic plasma doses. However, there remains a limited understanding of pharmaceutical bioaccumulation in estuarine environments. Here, we examined the influence of pH and salinity on bioconcentration of three pharmaceuticals in the Gulf killifish, Fundulus grandis. F. grandis were exposed to low levels of the ionizable pharmaceuticals carbamazepine, diltiazem, and diphenhydramine at two salinities (5 ppt, 20 ppt) and two pH levels (6.7, 8.3). pH influenced bioconcentration of select weak base pharmaceuticals, while salinity did not, suggesting that intestinal uptake via drinking does not appear to be a major exposure route of these pharmaceuticals in killifish. Compared to our previous pH dependent uptake observations with diphenhydramine in the fathead minnow model, killifish apparent volume of distribution values were markedly lower than fatheads, though killifish bioconcentration factors were similar at high pH and four fold higher at low pH than freshwater fish. Advancing an understanding of environmental gradient influences on pharmacokinetics among fish is necessary to improve bioaccumulation assessments and interpretation of toxicological observations for ionizable contaminants.

Determination of microcystins, nodularin, anatoxin-a, cylindrospermopsin, and saxitoxin in water and fish tissue using isotope dilution liquid chromatography tandem mass spectrometry.

Cyanobacteria can form dense blooms under specific environmental conditions, and some species produce secondary metabolites known as cyanotoxins, which present significant risks to public health and the environment. Identifying toxins produced by cyanobacteria present in surface water and fish is critical to ensuring high quality food and water for consumption, and protectionn of recreational uses. Current analytical screening methods typically focus on one class of cyanotoxins in a single matrix and rarely include saxitoxin. Thus, a cross-class screening method for microcystins, nodularin, anatoxin-a, cylindrospermopsin, and saxitoxin was developed to examine target analytes in environmental water and fish tissue. This was done, due to the broad range of cyanotoxin physicochemical properties, by pairing two extraction and separation techniques to improve isolation and detection. For the first time a zwitterionic hydrophilic interaction liquid chromatography column was evaluated to separate anatoxin-a, cylindrospermopsin, and saxitoxin, demonstrating greater sensitivity for all three compounds over previous techniques. Further, the method for microcystins, nodularin, anatoxin-a, and cylindrospermopsin were validated using isotopically labeled internal standards, again for the first time, resulting in improved compensation for recovery bias and matrix suppression. Optimized extractions for water and fish tissue can be extended to other congeners in the future. These improved separation and isotope dilution techniques are a launching point for more complex, non-targeted analyses, with preliminary targeted screening.

Corbicula fluminea rapidly accumulate pharmaceuticals from an effluent dependent urban stream.

Freshwater bivalve populations are stressed by watershed development at the global scale. Though pharmaceuticals released from wastewater treatment plant effluent discharges are increasingly reported to bioaccumulate in fish, an understanding of bioaccumulation in bivalves is less defined. In the present study, we examined accumulation of 12 target pharmaceuticals in C. fluminea during a 42 day in situ study in Pecan Creek, an effluent dependent wadeable stream in north central Texas, USA. Caged clams were placed at increasing distances (5 m, 643 m, 1762 m) downstream from a municipal effluent discharge and then subsampled on study days 7, 14, 28 and 42. Acetaminophen, caffeine, carbamazepine, diltiazem, diphenhydramine, fluoxetine, norfluoxetine, sertraline, desmethylsertraline, and methylphenidate were identified in C. fluminea whole body tissue homogenates via isotope dilution liquid chromatography-tandem mass spectrometry. Tissue concentrations ranged from low µg/kg (methylphenidate) to 341 µg/kg (sertraline). By study day 7, rapid and apparent pseudo-steady state accumulation of study compounds was observed in clams; this observation continued throughout the 42 d study. Notably, elevated bioaccumulation factors (L/kg) for sertraline were observed between 3361 and 6845, which highlights the importance of developing predictive bioaccumulation models for ionizable contaminants with bivalves. Future research is also necessary to understand different routes of exposure and elimination kinetics for pharmaceutical accumulation in bivalves.

Spatial and temporal influence of onsite wastewater treatment systems, centralized effluent discharge, and tides on aquatic hazards of nutrients, indicator bacteria, and pharmaceuticals in a coastal bayou.

In the rapidly urbanizing watersheds and estuaries flowing to the Gulf of Mexico in Texas, USA, instream flows are increasingly influenced by point source and nonpoint source discharges. Spatial and temporal tidal influences on water quality, especially for contaminants of emerging concern (CECs), is poorly understood in estuaries and coastal systems. We selected Dickinson Bayou, an urban estuary in Galveston County, Texas, for study because it has historically impaired water quality, receives point source discharge from one major wastewater treatment plant (WWTP), while also being influenced by high densities of onsite sewage facilities upstream in the watershed. We explored the occurrence and potential hazards of aquatic contaminants, including nutrients, indicator bacteria for pathogens, and CECs, in relation to this point source discharge, across seasons and at high and low tides. Aquatic contaminants and associated hazards varied significantly in relation to the WWTP discharge, and were influenced by onsite systems. In fact, spatiotemporal water quality varied by class of contaminants (e.g., nutrients, indicator bacteria, CECs), which indicates that traditional surface water monitoring activities should account for such environmental complexity. This study provides a diagnostic approach for future studies of emerging water quality challenges across gradients of rapidly urbanizing coastal bays and estuaries.

Spatio-temporal bioaccumulation and trophic transfer of ionizable pharmaceuticals in a semi-arid urban river influenced by snowmelt.

Bioaccumulation of pharmaceuticals in aquatic organisms is increasingly reported in the peer-reviewed literature. However, seasonal instream dynamics including occurrence and bioaccumulation across trophic positions are rarely studied, particularly in semiarid streams with flows influenced by seasonal snowmelt and municipal effluent discharges. Thus, we selected East Canyon Creek in Park City, Utah, USA to examine spatio-temporal bioaccumulation of select ionizable pharmaceuticals across trophic positions using trophic magnification factors calculated at incremental distances (0.15, 1.4, 13 miles) downstream from a municipal effluent discharge during spring (May), Summer (August), and fall (October). Nine target analytes were detected in all species during all sampling events. Trophic dilution was consistently observed for amitriptyline, caffeine, diphenhydramine, diltiazem, fluoxetine, and sertraline, regardless of seasonal instream flows or distance from effluent discharge. Calculated TMFs ranged from 0.01-0.71 with negative slopes observed for all regressions of chemical residue in tissue and trophic position. We further presents the first empirical investigation of normalizing pharmaceutical concentrations to lipid, phospholipid or protein fractions using pair matched fish samples. Empirical results identify that normalization of ionizable pharmaceutical residues in aquatic tissues to neutral lipids, polar lipids, or the total protein fraction is inappropriate, though bioaccumulation studies examining influences of internal partitioning (e.g., plasma proteins) are needed.

Influence of Diltiazem on Fathead Minnows Across Dissolved Oxygen Gradients.

Water resources in many arid to semi-arid regions are stressed by population growth and drought. Growing populations and climatic changes are influencing contaminant and water chemistry dynamics in urban inland waters, where flows can be dominated by, or even dependent on, wastewater effluent discharge. In these watersheds, interacting stressors such as dissolved oxygen and environmental contaminants (e.g., pharmaceuticals) have the potential to affect fish physiology and populations. Recent field observations from our group identified the calcium channel blocker (CCB) diltiazem in fish plasma exceeding human therapeutic doses (e.g., Cmin ) in aquatic systems impaired because of nonattainment of dissolved oxygen water quality standards. Therefore our study objectives examined: 1) standard acute and chronic effects of dissolved oxygen and diltiazem to fish, 2) influences of dissolved oxygen at criteria levels deemed protective of aquatic life on diltiazem toxicity to fish, and 3) whether sublethal effects occur at diltiazem water concentrations predicted to cause a human therapeutic level (therapeutic hazard value [THV]) in fish plasma. Dissolved oxygen × diltiazem co-exposures significantly decreased survival at typical stream, lake, and reservoir water quality standards of 5.0 and 3.0 mg dissolved oxygen/L. Dissolved oxygen and diltiazem growth effects were observed at 2 times and 10 times lower than median lethal concentration (LC50) values (1.7 and 28.2 mg/L, respectively). Larval fathead minnow (Pimephales promelas) swimming behavior following low dissolved oxygen and diltiazem exposure generally decreased and was significantly reduced in light-to-dark bursting distance traveled, number of movements, and duration at concentrations as low as the THV. Individual and population level consequences of such responses are not yet understood, particularly in older organisms or other species; however, these findings suggest that assessments with pharmaceuticals and other cardioactive contaminants may underestimate adverse outcomes in fish across dissolved oxygen levels considered protective of aquatic life. Environ Toxicol Chem 2018;37:2835-2850. © 2018 SETAC.