Branden L Johnson

The Dragonfly Mercury Project is a collaborative initiative that utilizes dragonfly larvae as biosentinels to monitor mercury concentrations across 180 national parks and other protected lands, including Grand Canyon National Park (GRCA). These indicators serve as surrogates for environmental risk and can indicate where fish consumption could pose health risks through exposure to mercury...

Significant variation in mercury (Hg) bioaccumulation is observed across the diversity of freshwater ecosystems in North America. While there is support for the major drivers of Hg bioaccumulation, the relative influence of different external factors can vary widely among waterbodies, which makes predicting Hg risk across large spatial scales particularly challenging. We modeled Hg...

The global prevalence of mercury (Hg) contamination and its complex biogeochemical cycling has resulted in elevated Hg concentrations in biota in remote and pristine environments. However, there is uncertainty in the relative importance of Hg deposition and landscape factors that control Hg cycling and bioaccumulation. To address this, we measured total mercury (THg) concentrations in...

The increasing frequency and severity of wildfires are among the most visible impacts of climate change. However, the effects of wildfires on mercury (Hg) transformations and bioaccumulation in stream ecosystems are poorly understood. We sampled soils, water, sediment, in-stream leaf litter, periphyton, and aquatic invertebrates in 36 burned (one-year post fire) and 21 reference...

Supplementary food resources (e.g., subsidies) associated with agriculture can benefit wildlife species, increasing predictability and availability of food. Avian scavengers including raptors often utilize subsidies associated with both recreational hunting and pest shooting on agricultural lands. However, these subsidies can contain lead (Pb) fragments if they are culled with Pb‐based...

Remote high-elevation lakes represent unique environments for evaluating the bioaccumulation of atmospherically deposited mercury through freshwater food webs, as well as for evaluating the relative importance of mercury loading versus landscape influences on mercury bioaccumulation. The increase in mercury deposition to these systems over the past century, coupled with their limited...

Invasive species are important drivers of environmental change in aquatic ecosystems and can alter habitat characteristics, community composition, and ecosystem energetics. Such changes have important implications for many ecosystem processes, including the bioaccumulation and biomagnification of contaminants through food webs. Mercury concentrations were measured in 2 nonnative and 1...

Mercury (Hg) is a globally distributed pollutant that poses considerable risks to human and wildlife health. Over the past 150 years since the advent of the industrial revolution, approximately 80 percent of global emissions have come from anthropogenic sources, largely fossil fuel combustion. As a result, atmospheric deposition of Hg has increased by up to 4-fold above pre-industrial...

Several polybrominated biphenyl ether (PBDE) congeners were found in all 175 osprey (Pandion haliaetus) eggs collected from the Columbia River Basin between 2002 and 2009. ΣPBDE concentrations in 2008–2009 were highest in osprey eggs from the two lowest flow rivers studied; however, each river flowed through relatively large and populous metropolitan areas (Boise, Idaho and Spokane...

Osprey (Pandion haliaetus) populations were adversely affected by DDT and perhaps other contaminants in the United States and elsewhere. Reduced productivity, eggshell thinning, and high DDE concentrations in eggs were the signs associated with declining osprey populations in the 1950s, 1960s, and 1970s. The species was one of the first studied on a large scale to bring contaminant...

We evaluated the effects of contaminants on osprey (Pandion haliaetus) nesting along the lower Duwamish River (LDR), Washington, and used the upper reach of the Willamette River (WR), Oregon, as a reference site. Osprey eggs and nestling blood (plasma) were collected at nests along the LDR (11 eggs, 7 plasmas) and WR (10 eggs, 6 plasmas) in 2006-07 and analyzed for contaminants...

Spatial and temporal assessments and reports of polybrominated diphenyl ether (PBDE) flame retardants in birds remain sparse. In the present study, PBDEs were detected in all 120 osprey (Pandion haliaetus) eggs collected. The eggs were collected from nests along the Columbia, Willamette and Yakima rivers of Oregon (OR) and Washington (WA) and in Puget Sound (WA) between 2002 and 2007...