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David Walters

Research Ecologist

Columbia Environmental Research Center

Office Phone: 573-876-1815
Fax: 573-876-1863
ORCID: 0000-0002-4237-2158

CERC - Tech Center
4200 New Haven Road
Columbia , MO 65201

Supervisor: Rip S Shively
We measured turbidity along transects from channel to marsh interior for 4 sites along the east coast of the United States at: Mockhorn Island, on the Eastern Shore of VA, USA; Plum Island in MA, USA; Goodwin Islands on the York River, VA USA; and the Altamaha River estuary, in GA, USA.
Survival and size of mayflies at each life stage, as well as MeHg concentrations in diatoms and mayflies exposed to low and high MeHg concentrations and a range of selenomethione (SeMet) concentrations.
Description of Work This work will investigate linkages between sediment PCB concentrations and subsequent exposure in riparian organisms living on land next to the river and harbor. This is an extension of prior work at the site that has been used by the Manistique River and Harbor Remediation Team (comprised of managers and scientists from USEPA GLNPO, USEPA ORD, NOAA, USACOE, USGS and the state of Michigan) to guide plans for delisting activities. Riparian spiders are important mediators of contaminant flux from aquatic systems to nearby terrestrial habitats. Aquatic insects accumulate contaminants in their larval form, and transport these contaminants to terrestrial ecosystems in their adult bodies. Spiders...
The St Louis River (SLR) is the second largest tributary to Lake Superior and a designated area of concern (AOC) due to past industrial contamination of organic chemicals and heavy metals, including mercury (Hg). Sediments, prey items (odonates, mixed benthic invertebrates, and spiders), and game fish were targeted within this study to determine if industrial sources of Hg were bioaccumulating into the food web. Samples from SLR were directly compared to a reference site in the Bad River, WI to assess if legacy contamination resulted in elevated Hg concentrations in comparisons to background regions with no known point sources. Carbon and nitrogen isotopes were also employed as food web tracers to determine if dietary...
We measured turbidity along a transect from channel to marsh interior for 1 year, beginning in June 2016 at a salt mash in the Altamaha River estuary. We measured turbidity (NTU) with three optical back scatter sensors to in a shore normal transect, with one in the channel (YSI 6600), and two on the marsh surface. The “marsh edge sensor” was 2.4m from the channel edge (Seapoint, RBR Solo) and the “marsh interior sensor” was 18m from the edge (Seapoint, RBR Duo; Figure 1c). The sensors measured every 15 minutes and were equipped with automatic wipers to reduce biofouling. Following retrieval, the turbidity time series data was filtered to remove any erroneous points and times when the sensors were fouled or exposed...
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