Dr. Brian Roberts
Associate Professor; REU Program Director

Mailing Address:
Louisiana Universities Marine Consortium
DeFelice Marine Center
8124 Highway 56
Chauvin, Louisiana 70344

Phone: 985-851-2821

Educational Background

  • Ph.D., 2004, Ecology and Evolutionary Biology
    Cornell University, Ithaca, NY
  • M.A., 1996, Marine Biology
    Boston University Marine Program, Marine Biological Laboratory, Woods Hole, MA
  • B.S., 1995, Biology and Philosophy
    College of William and Mary, Williamsburg, VA

Research Interests

  • The Roberts Lab is interested in understanding how ecosystems transform and retain nutrients and energy. We are particularly interested in examining how the mechanisms regulating the autotrophic/heterotrophic balance and the biogeochemical cycling and transport of materials along the continuum from headwater streams and lakes to large rivers, wetlands, estuaries and open-ocean ecosystems are altered as a result of human perturbations to the landscape (e.g. land use changes, fertilizer applications, climate change, oil spills, etc.). We are also interested in examining how restoration efforts might mitigate some of these deleterious impacts.
  • In our work, we seek to "open the black box" of ecosystems by attempting to understand the biotic and abiotic interactions occurring within them so we can better understand the factors that regulate important biological fluxes. Specifically, we have been involved in several projects studying the influence of particular species or communities at regulating ecosystem-scale processes [e.g. studying 1) the relative contribution of autotrophs and heterotrophs to ecosystem respiration and 2) the role of snails in both regulating periphyton communities as well as contributing to ecosystem-scale rates of nutrient cycling and respiration in stream ecosystems].

Current Projects

  • Current research in the Roberts Lab is broadly focused in three areas: 1) ecosystem ecology and biogeochemistry (particularly focused on terrestrial-aquatic and community-ecosystem linkages along the aquatic continuum), 2) human-induced environmental impacts on aquatic ecosystems and 3) restoration ecology. Our research team is currently involved in projects in multiple ecosystem types including headwater streams, rivers, baldcypress swamps, saltmarshes, estuaries and coastal oceans. The interdisciplinary and collaborative nature of our research lends itself to providing numerous research opportunities to students.
  • Estuarine Biogeochemistry: My research lab is leading a collaborative research project examining biogeochemical processing in the Atchafalaya River Delta Estuary Ecosystem. In our multi-faceted approach, we quantify important rates of nutrient and organic matter loading and processing over multiple time scales as water travels from the Atchafalaya River to the northern Gulf of Mexico. This project was originally funded by a LA BoR Support Fund RSC Grant and is currently supported by a NSF RAPID grant to examine the impact of the 2011 Mississippi and Atchafalaya River Flood. Collaborators: Nancy Rabalais (LUMCON), Brad Rosenheim (Tulane), Alex Kolker (LUMCON) and Gene Turner (LSU - BR).
  • Coastal Hypoxia in the northern Gulf of Mexico: The Roberts Lab is part of a team of scientists from LUMCON, LSU-BR, University of Michigan and NOAA studying and modeling the causes and consequences of hypoxia in the northern Gulf of Mexico. Our group is leading the effort to quantify rates and determine controls on carbon, oxygen and nutrient cycling processes in the region. This project is funded by NOAA.
  • Sediment dynamics and biogeochemical cycling in a developing deltaic system: Alex Kolker (LUMCON) and I have recently been awarded a grant from LA Sea Grant to examine the interaction of sediment dynamics and biogeochemistry in the Wax Lake Delta to better understand land building and habitat quality in river diversions.
  • Influences on ecosystem processes maintaining elevation in Gulf Coast Baldcypress swamps: We are collaborating with Beth Middleton (USGS NWRC) on a NSF RAPID grant studying the effects of hydrologic remediation efforts to prevent oil inundation of wetlands following the Deepwater Horizon Oil Spill. Specifically, we are examininig wetland soil decomposition, respiration, and greenhouse gas emission rates over an annual cycle in baldcypress swamps in Texas, Louisiana and Florida.
  • Effects of the Macondo Oil Spill on Coastal Ecosystems: I am one of the executive members of the steering committee for our recently funded GRI project (26 PIs from 12 institutions) to study the effects of the 2010 oil spill on coastal ecosystems. My research team, in collaboration with Anne Giblin (MBL) and Anne Bernhard (Connecticut College), is leading the wetland biogeochemistry and microbial ecology component of the larger project.
  • Stream Ecosystem Metabolism and Biogeochemistry: We have been measuring ecosystem metabolism (Gross Primary Production [GPP] and Ecosystem Respiration [ER] continuously in the West Fork of Walker Branch (Tennessee) since January 2004. This long-term record allows us to examine the ecosystem metabolism and nutrient cycling interactions and to improve our understanding of controls on these important processes at multiple temporal scales. Collaborators: Pat Mulholland (ORNL), Walter Hill (Illinois) and Natalie Griffiths (ORNL).
  • Kinetics and Dynamics of Coupled Carbon and Nitrogen Metabolism: Biogeochemical Capacity and Plasticity in Stream Ecosystems: My lab is collaborating with Jim Heffernan (FIU), Emily Bernhardt (Duke), Matt Cohen (Florida), Brian McGlynn (Montana State) and Bill McDowell (UNH) on a project using an integrated set of observational and experimental approaches, enabled by in-situ sensors, that provide novel descriptors of the coupling of metabolism and nutrient dynamics in stream ecosystems (NSF proposal pending).


Research Group

  • Matthew Rich, Research Assistant
    • B.S., 2013, Environmental, Soil and Water Science
      University of Arkansas - Fayetteville, Fayetteville, AR

  • Hillary Sullivan, Research Assistant
    • B.A., 2013, Environmental Science Conservation Biology
      Clark University, Worcester, MA

    • M.S., 2014, Biology
      Clark University, Worcester, MA

  • Regina Bledsoe, Student worker
    • B.S., 2015, Environmental Science
      Nicholls State University, Thibodaux, LA

  • Ciara Chambers, MS Student (Tulane)
    • B.S., 2012, Environmental Science
      Rensselaer Polytechnic Institute, Troy, NY

  • Lindsey Green, MS Student (LSU)
    • B.S., 2010, Biology
      McNeese State University, Lake Charles, LA


  • PDFs are available for all of the published articles listed below. The PDF links at the end of each article will take you directly to the article on the journal's website. If the article is a free-acess publication or if you or your library has an on-line subscription to the journal, you will be able to download and/or print the article directly from the link. If you do not have access to the pdf and would like a reprint of the article, please send me an email.
  • Marton JM and Roberts BJ. 2014. Spatial variability in phosphorus sorption dynamics in Louisiana salt marshes.JGR-Biogeosciences. doi: 10.1002/2013JG002486.[pdf]
  • Rosenheim B.E., Roe K.E., Roberts B.J., Kolker A.S, Allison M.A., Johannesson K.H. 2013. River discharge influences on particulate organic carbon age structure in the Mississippi/Atchafalaya River System. Global Biogeochemical Cycles 27:1-13. doi: 10.1029/2012GB004339.[pdf]
  • Lutz BD, Bernhardt ES, Roberts BJ, Mulholland PJ, Cory RM. 2012 Distinguishing terrestrial and autochthonous organic matter dynamics in a forested stream using kinetic enrichments and fluorescence spectroscopy. Limnology and Oceanography 57(1): 76-89.[pdf]
  • Lutz BD, Bernhardt ES, Roberts BJ, Mulholland PJ. 2011. Examining the coupling of carbon and nitrogen cycles in Appalachian streams: the role of dissolved organic nitrogen. Ecology 92(3): 720-732.[pdf]
  • Hill WR, Roberts BJ, Francoeur SN, Fanta SE. 2011. Resource energy and the autotrophic: heterotrophic balance in experimental streams. Journal of Ecology 99:454-463. DOI: 10.1111/j.1365-2745.2010.01785.x[pdf]
  • Fanta SE, Hill WR, Smith TB, Roberts BJ. 2010. Applying the light : nutrient hypothesis to stream periphyton. Freshwater Biology doi:10.1111/j.1365-2427.2009.02309.x[pdf]
  • Hill WR, Fanta SE, Roberts BJ. 2009. Combined effects of phosphorus and light on stream algae: implications for establishing stream nutrient criteria. Limnology and Oceanography 54(1):368-380.[pdf]
  • Mulholland PJ, Roberts BJ, Hill WR, Smith JG. 2009. Stream ecosystem responses to the 2007 spring freeze in the Southeastern United States: unexpected effects of climate change. Global Change Biology 15(7): 1767-1776. doi: 10.1111/j.1365-2486.2009.01864.x[pdf]
  • Hill WR, Fanta SE, Roberts BJ. 2008. 13C dynamics in benthic algae: effects of light, phosphorus, and biomass development. Limnology and Oceanography 53(4): 1217-1226. [pdf]
  • Roberts BJ, Mulholland PJ. 2007. In-stream biotic control on nutrient biogeochemistry in a forested headwater stream, West Fork of Walker Branch. JGR-Biogeosciences 112, G04002, doi:10.1029/2007JG000422 [pdf]
  • Roberts BJ, Mulholland PJ, Hill WR. 2007. Multiple scales of temporal variability in ecosystem metabolism rates: results from two years of continuous monitoring in a forested headwater stream. Ecosystems 10(4): 588-606. doi: 10.1007/s10021-007-9059-2[pdf]
  • Roberts BJ, Mulholland PJ, Houser JN. 2007. Effects of upland disturbance and in-stream restorations on hydrodynamics and ammonium uptake in headwater streams. Journal of the North American Benthological Society 26(1):38-53. [pdf]
  • Roberts BJ, Howarth RW. 2006. Nutrient and light availability regulate the relative contribution of autotrophs and heterotrophs to respiration in freshwater pelagic ecosystems. Limnology and Oceanography 51(1): 288-298. [pdf]
  • Roberts BJ, Russ ME, Ostrom NE. 2000. Rapid and precise determination of δ18O of dissolved and gaseous di-oxygen via gas chromatography-isotope ratio mass spectrometry. Environmental Science and Technology 34(11):2337-2341.[pdf]
  • Heberlig L, Valiela I, Roberts BJ. 1997. A field verification of the Waquoit Bay Nitrogen Loading Model. Biological Bulletin 193: 294-295.[pdf]
  • Lee RY, Joye SB, Roberts BJ, Valiela I. 1997. Release of N2 and N2O from salt marsh sediments subject to different land-derived nitrogen loads. Biological Bulletin 193:292-293.[pdf]