Jim Heffernan, Marco Marani, and Brad Murray, along with Matt Kirwan at the Virginia Institute of Marine Sciences, have received a new grant to measure and model the spatial extent of coastal wetlands at the continental scale. The basic idea is to extend our current understanding of salt marsh evolution up into watersheds, and explicitly link sediment delivery from the uplands with the internal estuarine processes that shape marsh distributions. This grant is based in large part on Anna Braswell's PhD research.
River Center PIs Emily Bernhardt, Brian McGlynn, and Jim Heffernan received a new grant to study the metabolic patterns of rivers at continental scales. Press release here.
Some new publications from the lab:
Two papers from our macrosystems project on Urban Homogenization
Resident attitudes toward ecosystem services in lawns
The convergence of residential microclimates across US cities
A fun and important paper led by Matt Ross, with Emily Bernhardt and Martin Doyle:
The history and importance of design in ecology
Megan Fork published this review paper, which arose from a special session in which she presented her MS research:
The effects of dissolved organic matter in aquatic ecosystems
Yikes! It has really been a long time since this page got updated.
Since our last post, a lot of things have happened. First, some news about people in the lab:
In August, Cathy Chamberlin joined the lab as a new PhD student. Cathy just submitted her first NSF Graduate Research Fellowship application.
In October, Xiaoli Dong joined the lab as a new post-doc. Xiaoli is working on spatial pattern formation in wetland landscapes, with a particular focus on the karst landscape of Big Cypress preserve.
Megan Fork spent the summer studying the effects of urban runoff on reservoirs, through a GO! Fellowship from Oak Ridge National Laboratory. A local newscast did a brief story about Megan, which you can see here.
Chelsea Clifford spent the summer characterizing the ecological structure of ditches throughout the coastal plain of North Carolina.
Anna Braswell spent the summer collecting sediment cores from wetlands along the NC coast.
Jim Heffernan visited the University of Wyoming, where collaborator and former sabbatical visitor Bob Hall played host. He also spent a few days at a SESYNC workshop, trying to understand innovation in urban socio-ecosystems.
I'll post other exciting news shortly.
We are pleased to announce that Cathy Chamberlin will join the Heffernan Lab in Fall of 2015 as a PhD student in the University Program in Ecology. Cathy graduated Summa Cum Laude from Yale University in 2012 with her BA in Chemistry. Her honors research addressed the use of geochemical proxies for paleoclimatology and paleoaltimetry, and was based on field work in New Zealand. After graduation, she worked in a molecular biology lab focused on circadian rhythms (and then came racing back to environmental science!) She has also taught English in Russia through a Fulbright fellowship. Based on her outstanding accomplishments and potential, Cathy was awarded a James B. Duke Fellowship. Congratulations Cathy and welcome aboard!
More good news on the funding front! PhD student Anna Braswell has received support from NC Sea Grant to conduct a geospatial analysis of wetland distributions along the SE coast of the US. Anna's work is focused on understanding how land-ocean links, coastal morphology, and marsh vegetation feedbacks influence the broad-scale distribution of salt marshes, and this more regionally focused award will allow us to develop some additional data analysis approaches. As part of the award, the NC Chapter of Student Wetland Scientists will be organizing a symposium about the drivers of marsh resilience and the selection of sites for ecological restoration. Way to go Anna!
I've been a bit quiet posting about the lab, but that's not because we haven't had any exciting news. A month or so ago, Megan Fork applied was awarded a GO fellowship to work at Oak Ridge National Laboratories. Megan's work there will focus on the metabolic dynamics of reservoirs and how they are influenced by pulses of urban run-off. Congratulations, Megan!
See the ad here. Review of applications will begin October 15th.
Alison Appling's paper on the theory of fine-scale nutrient dynamics is now available online at American Naturalist. The goal of the paper is to provide biological theory for the interpretation of passively-observed patterns such as diel variation and experimental manipulations such as pulsed nutrient additions. To do so, Alison developed a physiological model of nutrient uptake and growth, based on existing models that have been used to understand competition and productivity in aquatic ecosystems. The major findings are that 1) the presence of diel variation is a potential indicator of nutrient limitation status (with diel variation in a solute indicating that the varying nutrient is not limiting), 2) the shape of diel curves (or pulse responses) can vary strongly depending on physiological characteristics of biota, and 3) that differential lags among nutrients can de-couple them over diel or experimental time scales. We think this paper will inform the growing number of studies that use in situ nutrient sensors to characterize these fine-scale patterns.
The first chapter Dina Liebowitz's dissertation work is now available online in Freshwater Biology. This paper examines the relationships among environmental conditions (especially dissolved oxygen concentrations), the abundance of grazing snails, and the presence of benthic algae in Florida springs. By comparing data from field surveys both within and across springs, Dina showed that the abundance of snails (especially the genus Elimia) is the primary determinant of the abundance of algae in Florida springs. In addition, we found that algal abundance is generally either very high or very low, a pattern that is consistent with alternative stable states. Finally, our field survey also shows that oxygen concentrations, among other environmental controls, influences the abundance of snails. Putting these findings together, we suggest that even temporary declines in oxygen concentrations, which occur commonly in springs, could suppress snail populations and activity and allow algae to escape grazer control.
Most of the management attention in springs has emphasized nutrient concentrations as the major driver of algal mats, a hypothesis which we have challenged pretty strongly in an earlier paper that first articulated the oxygen-grazer-algae cascade. Dina's other chapters examine these processes experimentally, and lead to similar conclusions. Very exciting to have this work out, and congratulations Dina!
This is the homepage of the Heffernan Lab at Duke University. Here you can find all sorts of information about our research, teaching, and outreach. If you have any questions, contact Dr. Heffernan.
Dr. Jim Heffernan
I am an Assistant Professor in the Nicholas School of the Environment at Duke University. My research is focused on the causes and consequences of major changes in ecosystem structure, mostly in streams and wetlands.
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