Plastics and biofilm metabolism in urban streams
Plastic pollution (anthropogenic litter) is a ubiquitous issue in aquatic ecosystems. The ever increasing abundance of these materials raises a number of questions about their stability, habitability for biofilms, and long-term impacts of their persistence for ecosystem structure and function. My work examines the roles of plastic substrates in influencing the colonization and eventual structure and function of biofilms. Initial experiments are wrapping up and follow up work is in progress, so stay tuned for more!
Trace gas emissions from the Loch Vale Watershed
In conjunction with the Loch Vale Watershed project I am quantifying the emissions of CO2, CH4, and N2O from stream reaches along a topographical and ecological sequence in Rock Mountain National Park. Alpine and subalpine ecosystems are unique places to study stream ecology due to the great amount of variability within the streams in terms of discharge, biota, etc that can exist within a small area. This project has two main goals: 1) To determine the magnitude of emissions of important traces gasses over space and time within the watershed, and 2) Determine, for each site studied within the system, the relative roles of both biology and physics in creating these emissions. In addition to field work , I conducted extensive incubation experiments to determine the production and consumption potentials for each of these gasses by the microbes that reside within and on the sediments.
Siberian streams are strong sources of methane and carbon dioxide to the atmosphere
I quantified the dissolved load and diffusive flux of methane and carbon dioxide in a small, permafrost-underlain watershed near the town of Cherskiy in northeastern Siberia. The Arctic is a very heterogeneous environment that we know little about. What we do know is mostly based on measurements taken in Western Europe and Alaska...which unfortunately excludes most of the Arctic. This study was the first to quantify the diffusive flux of methane and carbon dioxide from a stream system in the Kolyma river basin. We found that methane fluxes from the streams can contribute up to 32% of the total watershed methane emission budget and conclude that these streams, unlike their counterparts in other systems worldwide, are potentially important sources of these gasses to the atmosphere.
For more information, check out the Polaris Project
All images and text © Sam Dunn 2011-2016