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San Diego, CA, United States

Carpenter K.D.,Oregon Water Science Center | Kuivila K.M.,Oregon Water Science Center | Hladik M.L.,California Water Science Center | Haluska T.,Oregon Water Science Center | Cole M.B.,Cole Ecological Inc.
Environmental Monitoring and Assessment | Year: 2016

Insecticide use in urban areas results in the detection of these compounds in streams following stormwater runoff at concentrations likely to cause toxicity for stream invertebrates. In this 2013 study, stormwater runoff and streambed sediments were analyzed for 91 pesticides dissolved in water and 118 pesticides on sediment. Detections included 33 pesticides, including insecticides, fungicides, herbicides, degradates, and a synergist. Patterns in pesticide occurrence reveal transport of dissolved and sediment-bound pesticides, including pyrethroids, from upland areas through stormwater outfalls to receiving streams. Nearly all streams contained at least one insecticide at levels exceeding an aquatic-life benchmark, most often for bifenthrin and (or) fipronil. Multiple U.S. EPA benchmark or criterion exceedances occurred in 40 % of urban streams sampled. Bed sediment concentrations of bifenthrin were highly correlated (p < 0.001) with benthic invertebrate assemblages. Non-insects and tolerant invertebrates such as amphipods, flatworms, nematodes, and oligochaetes dominated streams with relatively high concentrations of bifenthrin in bed sediments, whereas insects, sensitive invertebrates, and mayflies were much more abundant at sites with no or low bifenthrin concentrations. The abundance of sensitive invertebrates, % EPT, and select mayfly taxa were strongly negatively correlated with organic-carbon normalized bifenthrin concentrations in streambed sediments. Our findings from western Clackamas County, Oregon (USA), expand upon previous research demonstrating the transport of pesticides from urban landscapes and linking impaired benthic invertebrate assemblages in urban streams with exposure to pyrethroid insecticides. © 2016, The Author(s). Source

Mahardja B.,University of California at Davis | May B.,University of California at Davis | Feyrer F.,Bureau of Reclamation | Feyrer F.,California Water Science Center | And 4 more authors.
Conservation Genetics | Year: 2015

The discovery of two genetically distinct splittail populations within the San Francisco Estuary, one which spawns in the rivers of the Central Valley and another in the Petaluma and Napa Rivers of the San Pablo Bay, prompted the need to evaluate their degree of connectivity and relative sizes. We genotyped multiple age-0 splittail cohorts using 19 microsatellite loci to assess any spatiotemporal changes in the distribution of the two populations and estimate their effective population sizes (Ne). Genetic population assignments demonstrated that while age-0 splittail are predominantly spatially segregated by populations, substantial geographical overlap may occur during years of high precipitation. However, despite this periodic range overlap, the original observed population structure has persisted for nearly a decade which has included a similarly wet year. This suggests that the present population structure will likely persist in the future due to strong philopatry and/or adaptive differences. We also found that Ne estimates were generally lower for the San Pablo Bay population than the Central Valley population, which is consistent with the relative amount of habitat availability in the two locations and genetic diversity indices. The relative isolation and apparent lower Ne of the San Pablo Bay splittail population indicates a higher vulnerability to extinction. A more consistent monitoring effort of splittail in the Petaluma and Napa Rivers may be necessary in order to better understand the future viability of this less studied population. © 2014, Springer Science+Business Media Dordrecht. Source

Zamani K.,University of California at Davis | Bombardelli F.A.,University of California at Davis | Wuertz S.,University of California at Davis | Smith P.E.,California Water Science Center
World Environmental and Water Resources Congress 2010: Challenges of Change - Proceedings of the World Environmental and Water Resources Congress 2010 | Year: 2010

A deterministic 3D model for simulating hydrodynamics and salinity, based on the code Si3D, was implemented for San Francisco Bay. Several scenarios were modeled involving different months with varying estuarine conditions between October 2007 and June 2008. Bay bathymetry, coastal and river water levels, and salinity were used as input. This paper presents preliminary results of the modeling project. The paper discusses results obtained with two meshes and addresses the effects of boundary conditions on the numerical results. Predictions of tidal current patterns were developed for a study of water quality and quantitative pathogen monitoring in the sub-embayment of San Pablo Bay. © 2010 ASCE. Source

Nowell L.H.,California Water Science Center | Moran P.W.,Washington Water Science Center | Gilliom R.J.,California Water Science Center | Calhoun D.L.,Georgia Water Science Center | And 4 more authors.
Archives of Environmental Contamination and Toxicology | Year: 2013

Organic contaminants and trace elements were measured in bed sediments collected from streams in seven metropolitan study areas across the United States to assess concentrations in relation to urbanization. Polycyclic aromatic hydrocarbons, polychlorinated biphenyls, organochlorine pesticides, the pyrethroid insecticide bifenthrin, and several trace elements were significantly related to urbanization across study areas. Most contaminants (except bifenthrin, chromium, nickel) were significantly related to the total organic carbon (TOC) content of the sediments. Regression models explained 45-80 % of the variability in individual contaminant concentrations using degree of urbanization, sediment-TOC, and study-area indicator variables (which represent the combined influence of unknown factors, such as chemical use or release, that are not captured by available explanatory variables). The significance of one or more study-area indicator variables in all models indicates marked differences in contaminant levels among some study areas, even after accounting for the nationally modeled effects of urbanization and sediment-TOC. Mean probable effect concentration quotients (PECQs) were significantly related to urbanization. Trace elements were the major contributors to mean PECQs at undeveloped sites, whereas organic contaminants, especially bifenthrin, were the major contributors at highly urban sites. Pyrethroids, where detected, accounted for the largest share of the mean PECQ. Part 2 of this series (Kemble et al. 2012) evaluates sediment toxicity to amphipods and midge in relation to sediment chemistry. © 2012 Springer Science+Business Media New York (outside the USA). Source

Kemble N.E.,Columbia Environmental Research Center | Hardesty D.K.,Columbia Environmental Research Center | Ingersoll C.G.,Columbia Environmental Research Center | Kunz J.L.,Columbia Environmental Research Center | And 6 more authors.
Archives of Environmental Contamination and Toxicology | Year: 2013

Relationships between sediment toxicity and sediment chemistry were evaluated for 98 samples collected from seven metropolitan study areas across the United States. Sediment-toxicity tests were conducted with the amphipod Hyalella azteca (28 day exposures) and with the midge Chironomus dilutus (10 day exposures). Overall, 33 % of the samples were toxic to amphipods and 12 % of the samples were toxic to midge based on comparisons with reference conditions within each study area. Significant correlations were observed between toxicity end points and sediment concentrations of trace elements, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), or organochlorine (OC) pesticides; however, these correlations were typically weak, and contaminant concentrations were usually below sediment-toxicity thresholds. Concentrations of the pyrethroid bifenthrin exceeded an estimated threshold of 0.49 ng/g (at 1 % total organic carbon) in 14 % of the samples. Of the samples that exceeded this bifenthrin toxicity threshold, 79 % were toxic to amphipods compared with 25 % toxicity for the samples below this threshold. Application of mean probable effect concentration quotients (PECQs) based on measures of groups of contaminants (trace elements, total PAHs, total PCBs, OC pesticides, and pyrethroid pesticides [bifenthrin in particular]) improved the correct classification of samples as toxic or not toxic to amphipods compared with measures of individual groups of contaminants. © 2012 Springer Science+Business Media New York (outside the USA). Source

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