The Bernhardt and Heffernan labs were fortunate to have our friend and mentor Nancy Grimm as our guest this past week.  Nancy is a world-renowned expert in biogeochemistry, stream and riparian ecology, and urban ecosystems.  She is currently on leave from Arizona State Unviersity, where she was a collaborator and unofficial committee member, while she serves as program director for the National Science Foundation's Ecosystem Science Program.  

Nancy's first talk addressed her work in desert streams and their past and future response to climate variability.  Some of her lab's current work builds on my dissertation research on desert wetlands, which was very exciting to see!

Nancy's second talk focused on funding opportunities at NSF, covering programs as small as supplemental support for high school students to programs as large as the new foundation-wide sustainability initiatives.  There are lots of new programs at NSF as well as changes to how proposals and panels are working, so this was really helpful and interesting.

We also got a chance to take Nancy out to the Eno River, which runs through north Durham and eventually in to Falls Lake.  The land surrounding the Eno is largely undeveloped, thanks to the Eno River Land Trust, and the Eno River State Park is just beautiful.  We spent lots of time talking about floods, vegetation, and nitrogen in rivers; turning over rocks to see mayfly, stonefly and caddisfly larvae; and spooking turtles sunning on boulders and logs.  Good times.

Our paper describing diel and longitudinal patterns of nitrogen isotopes in the Ichetucknee River was just published in the Journal of Geophysical Research - Biogeosciences.  You can get it here.  

Building on our previous studies of diel variation in nutrient chemistry, we found large variation in N isotopes in the Ichetucknee River, FL.  Unfortunately, it appears that uptake by plants (autotrophic assimilation) and denitrifying microbes have similar effects in this system, so we were not able to discriminate between these pathways.  On the plus side, we observed some novel behaviors such as diel hysteresis, and found evidence that denitrification varies over the course of the day.  Check it out!