Publications

Knowledge of the habitats occupied by species is fundamental for the development of effective conservation and management actions. The collapse of pelagic fish species in the Sacramento–San Joaquin Delta, California, has triggered a need to better understand factors that drive their distribution and abundance. A study was conducted in summer–fall 2014 in an attempt to identify physical and biologi

Widespread mercury (Hg) contamination of aquatic systems in the Sierra Nevada of California, U.S., is associated with historical use to enhance gold (Au) recovery by amalgamation. In areas affected by historical Au mining operations, including the western slope of the Sierra Nevada and downstream areas in northern California, such as San Francisco Bay and the Sacramento River–San Joaquin River Del

Nitrapyrin is a bactericide that is co-applied with fertilizer to prevent nitrification and enhance corn yields. While there have been studies of the environmental fate of nitrapyrin, there is no documentation of its off-field transport to streams. In 2016, 59 water samples from 11 streams across Iowa were analyzed for nitrapyrin and its degradate, 6-chloropicolinic acid (6-CPA), along with three

Anthropogenic climate change amounts to a rapidly approaching, “new” stressor in the Sacramento–San Joaquin Delta system. In response to California’s extreme natural hydroclimatic variability, complex water-management systems have been developed, even as the Delta’s natural ecosystems have been largely devastated. Climate change is projected to challenge these management and ecological systems in

Stable isotopes present in water (δ2H, δ18O) have been used extensively to evaluate hydrological processes on the basis of parameters such as evaporation, precipitation, mixing, and residence time. In estuarine aquatic habitats, residence time (τ) is a major driver of biogeochemical processes, affecting trophic subsidies and conditions in fish-spawning habitats. But τ is highly variable in estuari

A data set was acquired on a shallow mudflat in south San Francisco Bay that featured simultaneous, co-located optical and acoustic sensors for subsequent estimation of suspended sediment concentrations (SSC). The optical turbidity sensor output was converted to SSC via an empirical relation derived at a nearby site using bottle sample estimates of SSC. The acoustic data was obtained using an acou

Reducing uncertainty in data inputs at relevant spatial scales can improve tidal marsh forecasting models, and their usefulness in coastal climate change adaptation decisions. The Marsh Equilibrium Model (MEM), a one-dimensional mechanistic elevation model, incorporates feedbacks of organic and inorganic inputs to project elevations under sea-level rise scenarios. We tested the feasibility of deri

The Potomac River is a large source of N to Chesapeake Bay, where reducing nutrient loads is a focus of efforts to improve trophic status. Better understanding of NO3– loss, reflected in part by diel variation in NO3– concentrations, may refine model predictions of N loads to the Bay. We analyzed 2 y of high-frequency NO3– sensor data in the Potomac to quantify seasonal variation in the magnitude

Seedling establishment is a critical step that may ultimately govern tree species’ distribution shifts under environmental change. Annual variation in the location of seed rain and microclimates results in transient “windows of opportunity” for tree seedling establishment across the landscape. These establishment windows vary at fine spatiotemporal scales that are not considered in most assessment

The occurrence of pesticide mixtures is common in stream waters of the United States, and the impact of multiple compounds on aquatic organisms is not well understood. Watershed Regressions for Pesticides (WARP) models were developed to predict Pesticide Toxicity Index (PTI) values in unmonitored streams in the Midwest and are referred to as WARP-PTI models. The PTI is a tool for assessing the rel

This paper reviews and highlights recent research findings on foodweb processes since an earlier review by Kimmerer et al. (2008). We conduct this review within a conceptual framework of the Delta-Suisun food web, which includes both temporal and spatial components. The temporal component is based on knowledge that the landscape has changed markedly from historical conditions. The spatial componen

Managed aquifer recharge is used to augment natural recharge to aquifers. It can be used to replenish aquifers depleted by pumping or to store water during wetter years for withdrawal during drier years. Infiltration from ponds is a commonly used, inexpensive approach for managed aquifer recharge.At some managed aquifer-recharge sites, the time when infiltrated water arrives at the water table is