Eric D. Stein

Watershed‐based sources of polycyclic aromatic hydrocarbons in urban storm water

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic and mutagenic compounds, ubiquitous in the air and water of urban environments, and have been shown to accumulate in coastal estuarine and marine sediments. Although previous studies have documented concentrations and loads of PAHs in urban runoff, little is known about the sources and temporal patterns of PAH loading from storm water. This study characterized the sources and temporal patterns of PAHs in urban storm water by analyzing PAH concentrations and loads from a range of homogeneous land use sites and in-river mass emission sites throughout the greater Los Angeles, California, USA, region. Samples were collected at 30- to 60-min intervals over the course of a storm during multiple storm events over a four-year period in order to investigate PAH sources and inter- and intrastorm patterns in loading. Polycyclic aromatic hydrocarbon storm fluxes ranged from 1.3 g/km2 for the largely undeveloped Arroyo Sequit watershed to 223.7 g/km2 for the highly urbanized Verdugo Wash watershed, with average storm fluxes being 46 times higher in developed versus undeveloped watersheds. Early-season storms repeatedly produced substantially higher loads than comparably sized late-season storms. Within individual storms, PAHs exhibited a moderate first flush with between 30 and 60% of the total PAH load being discharged in the first 20% of the storm volume. The relative distribution of individual PAHs demonstrated a consistent predominance of high-molecular-weight compounds indicative of pyrogenic sources.

Watershed and land use–based sources of trace metals in urban storm water

Trace metal contributions in urban storm water are of concern to environmental managers because of their potential impacts on ambient receiving waters. The mechanisms and processes that influence temporal and spatial patterns of trace metal loading in urban storm water, however, are not well understood. The goals of the present study were to quantify trace metal event mean concentration (EMC), flux, and mass loading associated with storm water runoff from representative land uses; to compare EMC, flux, and mass loading associated with storm water runoff from urban (developed) and nonurban (undeveloped) watersheds; and to investigate within-storm and within-season factors that affect trace metal concentration and flux. To achieve these goals, trace metal concentrations were measured in 315 samples over 11 storm events in five southern California, USA, watersheds representing eight different land use types during the 2000 through 2005 storm seasons. In addition, 377 runoff samples were collected from 12 mass emission sites (end of watershed) during 15 different storm events. Mean flux at land use sites ranged from 24 to 1,238, 0.1 to 1,272, and 6 to 33,189 g/km(2) for total copper, total lead, and total zinc, respectively. Storm water runoff from industrial land use sites contained higher EMCs and generated greater flux of trace metals than other land use types. For all storms sampled, the highest metal concentrations occurred during the early phases of storm water runoff, with peak concentrations usually preceding peak flow. Early season storms produced significantly higher metal flux compared with late season storms at both mass emission and land use sites.

Is DNA Barcoding Actually Cheaper and Faster than Traditional Morphological Methods: Results from a Survey of Freshwater Bioassessment Efforts in the United States?

Taxonomic identification accounts for a substantial portion of cost associated with bioassessment programs across the United States. New analytical approaches, such as DNA barcoding have been promoted as a way to reduce monitoring costs and improve efficiency, yet this assumption has not been thoroughly evaluated. We address this question by comparing costs for traditional morphology-based bioassessment, the standard Sanger sequencing-based DNA barcoding approach, and emerging next-generation (NGS) molecular methods. Market demand for molecular approaches is also assessed through a survey of the level of freshwater bioassessment effort in the United States across multiple habitat types (lakes, streams, wetlands) and indicators (benthic invertebrates, fish, algae). All state and regional level programs administered by public agencies and reported via agency web sites were included in the survey. Costs were based on surveys of labs and programs willing to provide such information. More than 19,500 sites are sampled annually across the United States, with the majority of effort occurring in streams. Benthic invertebrates are the most commonly used indicator, but algae and fish comprise between 35% and 21% of total sampling effort, respectively. We estimate that between

How effective has the Clean Water Act been at reducing pollutant mass emissions to the Southern California Bight over the past 35 years

104 and

Validation of a Wetland Rapid Assessment Method: Use of Epa's Level 1-2-3 Framework for Method Testing and Refinement

193 million is spent annually on routine freshwater bioassessment in the United States. Approximately 30% of the bioassessment costs are comprised of the cost to conduct traditional morphology-based taxonomy. Current barcoding costs using Sanger sequencing are between 1.7 and 3.4 times as expensive as traditional taxonomic approaches, excluding the cost of field sampling (which is common to both approaches). However, the cost of NGS methods are comparable (or slightly less expensive) than traditional methods depending on the indicator. The promise of barcoding as a cheaper alternative to current practices is not yet realized, although molecular methods may provide other benefits, such as a faster sample processing and increased taxonomic resolution.

Cryptic Biodiversity in Streams: A Comparison of Macroinvertebrate Communities Based on Morphological and DNA Barcode Identifications

The Clean Water Act (CWA) has regulated discharges of contaminants since 1972. However, evaluations of the CWA’s effectiveness at improving regional water quality are lacking, primarily because integration of monitoring data from multiple dischargers to assess cumulative effects is not required. A rare opportunity exists to assess CWA effectiveness by integrating mass emissions data from all major sources of contaminants to the Southern California Bight from 1971 to 2000. While the coastal population grew by 56% and total effluent volume increased 31% since 1971, mass emissions of nearly all constituents decreased since passage of the CWA, most by greater than 65%. Publicly owned treatment works were the dominant point source of many contaminants, but also accounted for the greatest reductions in pollutant discharge since 1971. As point source treatment has improved, the relative contribution of non-point sources, such as storm water runoff has increased. Despite the increased importance of storm water discharges, regional monitoring and data compilation of this source is lacking, making it difficult to accurately assess trends in non-point source discharge.

INFLUENCE OF GEOLOGIC SETTING ON SLOPE WETLAND HYDRODYNAMICS

Wetland rapid assessment has become popular in a variety of applications. Because rapid assessments rely on observable field indicators as surrogates for direct measures of condition, they must be validated against independent data. Here we present a case study of the validation of the riverine and estuarine modules of the California Rapid Assessment Method (CRAM). We evaluated responsiveness of the method to “good” vs. “poor” wetland condition, ability to represent a range of conditions, internal redundancy, alternative combination rules for constituent metrics, and reproducibility of results. Because no independent, concurrently collected measure of condition directly reflecting the same elements comprising CRAM was available for validation, we demonstrate the use of existing monitoring and assessment data on avian diversity, benthic macroinvertebrate indices, and plant community composition. Results indicate that CRAM is an effective tool for assessing general riverine and estuarine wetland condition based on its correspondence with multiple independent assessments of condition. Reproducibility analysis revealed several problematic metrics where ambiguous language or metric construction led to high inter-team error rates. Addressing these issues improved overall average error to within 5%. This study demonstrates that, when validated, rapid assessment methods provide a meaningful and reliable tool for assessing wetland condition.

Does DNA barcoding improve performance of traditional stream bioassessment metrics

Abstract: Species-level identifications are difficult or impossible for many larval aquatic macroinvertebrates. We described the taxonomic composition of macroinvertebrate communities from 5 coastal streams in 3 neighboring catchments in southern California. We compared taxonomic identifications based on deoxyribonucleic acid (DNA) barcoding (cytochrome c oxidase subunit I [COI]) with morphological identifications of the same specimens. We examined 5870 individuals, and barcodes with sequence lengths >350 base pairs (bp) for 91% of those specimens. We used the naturally occurring gaps in divergence frequencies for each order (usually 2% level of genetic divergence) to delimit putative species for all taxonomic groups except Simulium (3%) and Baetis (1%). We identified 200 species across these 5 streams. We identified 104 more species via barcodes than via morphology (200 vs 96, a 108% increase). Richness increases were greatest for Chironomidae (60 more species), Ephemeroptera (10 species), Acari (10 species), and Trichoptera (6 species). Forty-five percent of the genera/species identified morphologically represented >2 species. Many (86) species identified with barcodes were represented by only 1 or 2 specimens and were found at only 1 stream. Thus, species rarity (either spatially or numerically) appears to be a common characteristic of these streams. Barcoding increased total richness at each site by 12 to 40 taxa over morphology alone, and increased the difference between reference and impact sites in terms of lost taxa. These results suggest that macroinvertebrate biodiversity in streams has been underestimated substantially in the past, as has the biodiversity lost in response to environmental stress. The potential of DNA barcoding will not be fully realized until we can assign traits, such as habitat preference, ecological function, and pollution tolerance, at the species level.

Stormwater contaminant loading following southern California wildfires

Slope wetlands exist where topographic or stratigraphic conditions allow ground water to intersect the surface, creating a zone of perennial or near-perennial moisture. The condition and resiliency of slope wetlands are, therefore, controlled by their hydrodynamics (i.e., the movement and action of water in the wetland) and recharge mechanisms. Understanding the mechanisms by which water flows into and through the wetland is essential for accurate assessment of potential indirect impacts and for the development of management measures geared toward preserving slope wetland functions. We investigated the physical and biological properties of twenty slope wetlands in southern California, USA to gain a better understanding of how their geologic setting influenced water movement through the wetlands and of the plant community composition in the wetland. Principle Components Analysis (PCA) separated the slope wetlands into three distinct groups based on geologic setting: those located in bedrock landslides, those associated with faults, and those associated with alluvial/colluvial deposits. Ground-water monitoring and hydrogeologic analysis showed that wetlands in alluvial/colluvial deposits respond quickly to precipitation, and subsurface water levels stay near the ground-surface elevation for extended periods of time. In contrast, subsurface water levels in bedrock landslide slope wetlands respond more slowly to precipitation, show greater variation over time, and ultimately decline more quickly after the cessation of recharge events. These observations (along with analysis of ground-water chemistry) indicate that wetlands in alluvial/colluvial deposits are likely supported by large, relatively stable volumes of ground water. In contrast, wetlands located in bedrock landslides are likely recharged from relatively localized ground-water sources with smaller storage volumes and greater interannual variability. Wetlands located along faults have an intermediate level of variation in moisture regime, indicating that their association with a fault may be providing a conduit for water delivery to the wetland. Plant species diversity did not differ between subclasses, although wetlands in alluvial/colluvial deposits supported slightly greater proportions of alkaline plant species. Understanding the different recharge characteristics of each subclass will allow for more informed decision-making regarding protection and management of slope wetlands.

Fecal indicator bacteria (FIB) levels during dry weather from Southern California reference streams

Abstract: Benthic macroinvertebrate community composition is used to assess wetland and stream condition and to help differentiate the effects of stressors among sites. Deoxyribonucleic acid (DNA) barcoding has been promoted as a way to increase taxonomic resolution and, thereby, to increase the sensitivity of bioassessment metrics. We compared the ability of several commonly used bioassessment metrics calculated with data derived from morphology and from DNA barcoding to detect differences in stream condition of 6 paired sites in southern California with relatively subtle impacts to habitat. At each site, we sampled an upstream (reference) reach and a downstream (impact) reach with armored stream banks. We counted and identified ∼600 organisms/ sample based on morphology (generally to species, but to genus for midges). We then extracted mitochondrial (mt)DNA from each individual and sequenced the ∼658-base pair (bp) barcoding region of the cytochrome c oxidase subunit I (COI) gene. Most (91%) organisms yielded sequences >350 bp in length, but high failure rates for all taxa collected from 1 stream required that we exclude it from analysis. Sixteen metrics calculated with morphological data showed subtle but not significant differences in community composition between armored and unarmored reaches. The statistical power of 10 of the 16 metrics was substantially higher when calculated with DNA than with morphological data, and we were able to discern differences between armored and unarmored reaches with the DNA data. These differences were associated with increased taxonomic richness detected for midges, mayflies, noninsects, caddisflies, and black flies when DNA data were used. Our results suggest that identifications based on DNA barcoding have the potential to improve power to detect small changes in stream condition.