Carbon dynamics in freshwater experimental aquatic systems: implications of climate warming

Bibliography: p. 111-141Some pages are in colour

Experimental warming increases CO2 saturation in a shallow prairie pond

There is an urgent need to understand the effect of climate warming on the carbon dynamics of lakes and ponds in order to assess contributions to global carbon budgets. Currently, we are unable to predict how the exchange of carbon gases (i.e. CO2) across the air–water boundary and organic carbon storage in the sediments will be altered with realistic warming scenarios downscaled from climatic models. Given the prevalence of shallow systems and tight atmospheric coupling, we conducted a mesocosm experiment to test the impacts of warming on CO2 saturation in a shallow prairie pond. We outline and test three possible scenarios for the effect of warming on the CO2 saturation of ponds, resulting in either an increase, decrease or no net effect for CO2 saturation. We show that with approximately a two-degree (ºC) increase in average water temperature, the pCO2 of the warmed mesocosms was nine times greater than the ambient temperature mesocosms by the end of the 5-week experiment. Changes in water colour (a measure of dissolved organic carbon) in warmed systems indicate that decomposition of organic matter in the sediments and water column was the main contributor to the increase in pCO2 in the warmed mesocosms. Our results show that with warming, the release of CO2 from shallow ponds to the atmosphere will increase and carbon storage in the sediments will decrease, altering the current functioning of shallow prairie ponds and influencing the contribution of ponds to the global carbon cycle

Caribou Conservation Conundrum

The National Center for Case Study Teaching in Science has worked with dozens of scientists over the years to bring forth a range of wonderful teaching resources. The case study method is well-known in the field, and the offerings on the main website cover biology, ecology, zoology, and other disciplines. This particular case study was authored by Kyla Flanagan of the University of Calgary and Jalene M. LaMontagne of DePaul University, and it looks at how scientists and others might work to preserve the habitat of the caribou in northern Alberta. On the site, visitors can read an abstract of the case study, peruse its objectives, and then dive right in. Users will find a set of Teaching Notes, Supplemental Materials, and comments from those who have utilized the materials. It's a rather useful teaching tool, especially for those in the biological sciences

Global patterns and drivers of ecosystem functioning in rivers and riparian zones

Abstract River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to conduct a global-scale field experiment in greater than 1000 river and riparian sites. We found that Earth’s biomes have distinct carbon processing signatures. Slow processing is evident across latitudes, whereas rapid rates are restricted to lower latitudes. Both the mean rate and variability decline with latitude, suggesting temperature constraints toward the poles and greater roles for other environmental drivers (e.g., nutrient loading) toward the equator. These results and data set the stage for unprecedented “next-generation biomonitoring” by establishing baselines to help quantify environmental impacts to the functioning of ecosystems at a global scale