Influence of Hydroscape Configuration on Watershed Carbon Signatures
The movement of water across a landscape links aquatic ecosystems together as cohesive networks or hydroscapes. Consequently, the biogeochemical signatures of any individual aquatic ecosystem represent not only in situ processes, but also processes occurring in upstream linked systems. Despite the prevalence of linkages among aquatic ecosystems, very little is known regarding how configurations of aquatic elements embedded in the terrestrial landscape function to control the movement of chemicals and energy. Thus, the overarching goal of this research is to address how the configuration of different aquatic ecosystems embedded in a hydroscape influences watershed carbon signatures (more).
Interactions between Geomorphology and Wrack Disturbance in Tidal Creeks
Disturbance is often regarded as playing a central role in determining ecosystem structure and function. In many cases, disturbances can create spatial heterogeneity within an ecosystem. Tidal creeks provide corridors for wrack transport into and deposition on salt marshes. Deposited wrack mats often create bare spots by killing not only the surface vegetation, but also the sub-surface root structure, and the bare spots may persist for long periods of time. Fisher et al (2000) along with others have argued that wrack mats, dead vegetation scoured and deposited in salt marshes, may be a primary mechanism for establishing patches of non dominant vegetation within a tidal creek marsh. Here we focus on how tidal creek geomorphology may influence the spatial distribution of disturbance patches and how ecological disturbances may provide a mechanism for geomorphic change along tidal creeks.
East Branch of the Pecetonica Stream Restoration Project
Humans have left a lasting fingerprint on the landscape. In agriculturally dominated landscapes such as the midwest, agriculture activities have resulted in the deposition of up to several meters of soil in valley floors along many streams. Consequently, streams in these regions are often severely insized, heavily shaded, dominated by fine anthropogenic sediments, and disconnected from their natural floodplain. A recent approach to restore these systems has been to excavate the anthropogenic floodplain sediments in order to reconnect the streams to their historic floodplain. The primary focus of my research is to examine how restoration techniques like this influence ecosystem structure and function, and, more specifically, the potential for these techniques to enhance instream nutrient retention.
Brinton Arsenic Mine Study
On October 31, 2001, the U.S. EPA announced that the drinking water standard for arsenic will be lowered from 50 to 10 mg/L, due to the carcinogenic and toxic effects of arsenic on humans. It is well-known that arsenic is readily transported in natural waters and that its form, speciation, and concentration are affected by biogeochemical reactions. This project focuses broadly on the hydrologic, geochemical, and biological controls on the mobility of arsenic in a stream-aquifer system impacted by past mining activities. Within this broad umbrella, my research has focused specifically on how natural and anthroprogenic disturbances interact to alter basic ecosystem structure and function