Richard L. Kiesling

GROWTH AND TOXICITY OF PRYMNESIUM PARVUM (HAPTOPHYTA) AS A FUNCTION OF SALINITY, LIGHT, AND TEMPERATURE

The growth rate, stationary cell concentration, and toxicity of Prymnesium parvum N. Carter were measured using a strain isolated from Texas inland waters. We used a multifactor experimental approach with multiple regression analysis to determine the importance of environmental factors, including temperature, light, and salinity to these algal measurements. Exponential growth rate was unimodal in relation to temperature, salinity, and irradiance, with an estimated maximal growth of 0.94 d−1 occurring at 27°C, 22 practical salinity units (psu), and 275 μmol photons·m−2·s−1. Stationary cell concentrations also had unimodal responses to temperature and salinity but increased with irradiance. Maximal cell concentrations were estimated to occur at 26°C and 22 psu. Both maximum growth rate and highest stationary cell concentrations were measured at levels of each factor resembling warm, estuarine conditions that differ from the conditions under which blooms occur in inland waters in the southwestern United States. Acute toxicity to fish was highest at the lowest salinity and temperature levels, conditions not optimal for exponential growth but similar to those under which blooms occur in inland waters. Our results imply that summer blooms could occur in inland waters of the southwestern United States. Generally, they have not, suggesting that factors other than those investigated in this research influence bloom dynamics.

Anthropogenic tracers, endocrine disrupting chemicals, and endocrine disruption in Minnesota lakes

Concentrations of endocrine disrupting chemicals and endocrine disruption in fish were determined in 11 lakes across Minnesota that represent a range of trophic conditions and land uses (urban, agricultural, residential, and forested) and in which wastewater treatment plant discharges were absent. Water, sediment, and passive polar organic integrative samplers (POCIS) were analyzed for steroidal hormones, alkylphenols, bisphenol A, and other organic and inorganic molecular tracers to evaluate potential non-point source inputs into the lakes. Resident fish from the lakes were collected, and caged male fathead minnows were deployed to evaluate endocrine disruption, as indicated by the biological endpoints of plasma vitellogenin and gonadal histology. Endocrine disrupting chemicals, including bisphenol A, 17β-estradiol, estrone, and 4-nonylphenol were detected in 90% of the lakes at part per trillion concentrations. Endocrine disruption was observed in caged fathead minnows and resident fish in 90% of the lakes. The widespread but variable occurrence of anthropogenic chemicals in the lakes and endocrine disruption in fish indicates that potential sources are diverse, not limited to wastewater treatment plant discharges, and not entirely predictable based on trophic status and land use.

Identifying Non-point Sources of Endocrine Active Compounds and Their Biological Impacts in Freshwater Lakes

Contaminants of emerging concern, particularly endocrine active compounds (EACs), have been identified as a threat to aquatic wildlife. However, little is known about the impact of EACs on lakes through groundwater from onsite wastewater treatment systems (OWTS). This study aims to identify specific contributions of OWTS to Sullivan Lake, Minnesota, USA. Lake hydrology, water chemistry, caged bluegill sunfish (Lepomis macrochirus), and larval fathead minnow (Pimephales promelas) exposures were used to assess whether EACs entered the lake through OWTS inflow and the resultant biological impact on fish. Study areas included two OWTS-influenced near-shore sites with native bluegill spawning habitats and two in-lake control sites without nearby EAC sources. Caged bluegill sunfish were analyzed for plasma vitellogenin concentrations, organosomatic indices, and histological pathologies. Surface and porewater was collected from each site and analyzed for EACs. Porewater was also collected for laboratory exposure of larval fathead minnow, before analysis of predator escape performance and gene expression profiles. Chemical analysis showed EACs present at low concentrations at each study site, whereas discrete variations were reported between sites and between summer and fall samplings. Body condition index and liver vacuolization of sunfish were found to differ among study sites as did gene expression in exposed larval fathead minnows. Interestingly, biological exposure data and water chemistry did not match. Therefore, although results highlight the potential impacts of seepage from OWTS, further investigation of mixture effects and life history factor as well as chemical fate is warranted.

Evaluation of internal loading and water level changes: implications for phosphorus, algal production, and nuisance blooms in Kabetogama Lake, Voyageurs National Park, Minnesota

Abstract Hydrologic manipulations have the potential to exacerbate or remediate eutrophication in productive reservoirs. Dam operations at Kabetogama Lake, Minnesota, were modified in 2000 to restore a more natural water regime and improve water quality. The US Geological Survey and National Park Service evaluated nutrient, algae, and nuisance bloom data in relation to changes in Kabetogama Lake water levels. Comparison of the results of this study to previous studies indicates that chlorophyll a concentrations have decreased, whereas total phosphorus (TP) concentrations have not changed significantly since 2000. Water and sediment quality data were collected at Voyageurs National Park during 2008–2009 to assess internal phosphorus loading and determine whether loading is a factor affecting TP concentrations and algal productivity. Kabetogama Lake often was mixed vertically, except for occasional stratification measured in certain areas, including Lost Bay in the northeastern part of Kabetogama Lake. Stratification, higher bottom water and sediment nutrient concentrations than in other parts of the lake, and phosphorus release rates estimated from sediment core incubations indicated that Lost Bay is one of several areas that may be contributing to internal loading. Internal loading of TP is a concern because increased TP may cause excessive algal growth including potentially toxic cyanobacteria.

Trace organic contaminant (TOrC) mixtures in Minnesota littoral zones: Effects of on-site wastewater treatment system (OWTS) proximity and biological impact

On-site wastewater treatment systems (OWTSs) are an international wastewater management strategy for rural and semi-rural communities without access to centralized sewage treatment. These systems are a suspected source of trace organic contaminants (TOrCs) that may be responsible for endocrine disrupting effects to resident fish species in Minnesota Lakes. This study assessed localized porewater concentrations of TOrCs in near-shore environments across five Minnesota Lakes. Sampling sites were designated as either likely (HOME) or unlikely (REF) to receive OWTS discharges based on their proximity to shoreline households. Sampling sites also served as sunfish spawning habitats concurrently studied for biological impacts to resident adult males. Two-group hypothesis tests demonstrated significantly (p = .02) higher total TOrC concentrations in HOME (Mean = 841 ng/L) versus REF (Mean = 222 ng/L) sites. HOME sites also contained a wider suite of TOrC detections relative to REF sites. The distance to the nearest household (most proximal distance; MPD) negatively correlated (r = -0.62) with total TOrC concentrations. However, 2,4-D and DEET were major contributors to these total concentrations, suggesting that anthropogenic influence from households may not be exclusively attributed to OWTS discharges. Further, TOrC presence and elevated nitrogen concentrations in REF site porewater suggest additional, non-household TOrC discharges to these lakes. Significantly higher blood concentrations of vitellogenin (p = .03) and 11-ketotestosterone (p = .01) were observed in adult male sunfish captured from HOME versus REF sites. Comparisons between chemical and biological data indicate enhanced bioactive effects of co-contaminants. The findings from this study demonstrate multiple diffuse transport pathways contribute to the presence of biologically active TOrC mixtures in Minnesota Lakes, and mitigation efforts should consider minimizing residential inputs of chemicals associated with both outdoor and OWTS activity.

Effects of urban stormwater and iron‐enhanced sand filtration on Daphnia magna and Pimephales promelas

Urban stormwater is an important but incompletely characterized contributor to surface-water toxicity. The present study used 5 bioassays of 2 model organisms (Daphnia magna and fathead minnow, Pimephales promelas) to investigate stormwater toxicity and mitigation by full-scale iron-enhanced sand filters (IESFs). Stormwater samples were collected from major stormwater conveyances and full-scale IESFs during 4 seasonal events (winter snowmelt and spring, early summer, and late summer rainfalls) and analyzed for a diverse range of contaminants of emerging concern including pharmaceuticals, personal care products, industrial chemicals, and pesticides. Concurrently, stormwater samples were collected for toxicity testing. Seasonality appeared more influential and consistent than site type for most bioassays. Typically, biological consequences were least in early summer and greatest in late summer and winter. In contrast with the unimproved and occasionally reduced biological outcomes in IESF-treated and late summer samples, water chemistry indicated that numbers and total concentrations of detected organic chemicals, metals, and nutrients were reduced in late summer and in IESF-treated stormwater samples. Some potent toxicants showed more specific seasonality (e.g., high concentrations of polycyclic aromatic hydrocarbons and industrial compounds in winter, pesticides in early summer and spring, flame retardants in late summer), which may have influenced outcomes. Potential explanations for insignificant or unexpected stormwater treatment outcomes include confounding effects of complex stormwater matrices, IESF nutrient removal, and, less likely, unmonitored toxicants. Environ Toxicol Chem 2018;37:2645-2659.

Predicting the occurrence of chemicals of emerging concern in surface water and sediment across the U.S. portion of the Great Lakes Basin

Chemicals of emerging concern (CECs) are introduced into the aquatic environment via various sources, posing a potential risk to aquatic organisms. Previous studies have identified relationships between the presence of CECs in water and broad-scale watershed characteristics. However, relationships between the presence of CECs and source-related watershed characteristics have not been explored across the Great Lakes basin. Boosted regression tree (BRT) analyses were used to develop predictive models of CEC occurrence in water and sediment throughout 24 U.S. tributaries to the Great Lakes. Models were based on the distribution of both broad-scale and source-related watershed characteristics. Twenty-one upstream watershed characteristics, including land cover, number of permitted point sources, and distance to point sources were used to develop models predicting the probability of CEC occurrence in surface water and bottom sediment. Total accuracy of BRT models ranged from 66% to 94% for both matrices. All 21 watershed characteristics were important predictor variables in at least one surface-water model; twenty were important in at least one bottom-sediment model. Among the model variables, developed land use and distance to point sources were important predictors of the presence of CEC classes in both water and sediment. Although limitations exist, BRT models are one tool available for assessing vulnerability of fisheries and aquatic resources to CEC occurrences.

Environmentally relevant chemical mixtures of concern in waters of United States tributaries to the Great Lakes

The North American Great Lakes are a vital natural resource that provide fish and wildlife habitat, as well as drinking water and waste assimilation services for millions of people. Tributaries to the Great Lakes receive chemical inputs from various point and nonpoint sources, and thus are expected to have complex mixtures of chemicals. However, our understanding of the co-occurrence of specific chemicals in complex mixtures is limited. To better understand the occurrence of specific chemical mixtures in the US Great Lakes Basin, surface water from 24 US tributaries to the Laurentian Great Lakes was collected and analyzed for diverse suites of organic chemicals, primarily focused on chemicals of concern (e.g., pharmaceuticals, personal care products, fragrances). A total of 181 samples and 21 chemical classes were assessed for mixture compositions. Basin wide, 1664 mixtures occurred in at least 25% of sites. The most complex mixtures identified comprised 9 chemical classes and occurred in 58% of sampled tributaries. Pharmaceuticals typically occurred in complex mixtures, reflecting pharmaceutical-use patterns and wastewater facility outfall influences. Fewer mixtures were identified at lake or lake-influenced sites than at riverine sites. As mixture complexity increased, the probability of a specific mixture occurring more often than by chance greatly increased, highlighting the importance of understanding source contributions to the environment. This empirically based analysis of mixture composition and occurrence may be used to focus future sampling efforts or mixture toxicity assessments. Integr Environ Assess Manag 2018;14:509-518.