My principal basic research interest at the present time is the transport of suspended particles by turbulent fluids—especially the transport of fine particulate organic matter, microorganisms, and invertebrate larvae in streams. In addition, I am continuing my earlier work on theoretical problems dealing with the role of basic physiological processes in the dynamics of size-structured populations. Both of these themes also have important applied aspects, and I am pursuing some of these in my applied research program (see below).

My work on turbulent transport of suspended particles was originally inspired by a paper by Denny and Shibata (1989), which dealt with transport of invertebrate larvae in the marine surf zone. I have developed a stochastic diffusion model, called the Local Exchange Model, to describe the random-like dynamics of individual particles suspended in a turbulent fluid. The model can be applied to the transport of molecules, seston, microorganisms, and many invertebrates in streams, estuaries, and marine systems, to the transport of microorganisms, pollen, seeds, and spores in terrestrial systems, and to a variety of other transport problems.

As noted by McNair et al. (1997), a complete theory of particle transport in turbulent aquatic systems can be decomposed into at least four problems: (1) the entrainment problem (how does a particle on the bottom—or other solid surface—become entrained into the water column?), (2) the travel-time problem (how long does a suspended particle take to hit the bottom for the first time, following release from a given initial elevation?), (3) the travel-distance problem (how far does a suspended particle travel before hitting the bottom for the first time, following release from a given initial elevation?), and (4) the settlement problem (what determines whether a particle settles on the bottom when it hits, rather than bouncing off and immediately returning to the water column?). Thus far, I have derived equations governing the probability distribution and moments of the hitting time, hitting distance, settling time, and settling distance (the hitting time and distance are the travel time and distance at which a suspended particle hits the bottom for the first time; the settling time and distance are the travel time and distance at which a suspended particle settles for the first time). I have applied these theoretical results to empirical settling-distance distributions for ¹⁴C-labeled natural FPOM in streams, and I am currently appling them to data for additional types and sizes of particles in streams and flumes.

At the present time, my principal applied research interests are in the individual- and population-level effects of novel chemical stressors (e.g., antibiotics, nanoparticles) on populations of aquatic and soil organisms, watershed-scale modeling of effects of landcover- and landuse-derived stressors on stream health, and the ecology and control of exotic invasive plants in urban parks. A guiding belief underlying this work is that applied research can and should be conducted in essentially the same way as basic research; i.e, using the same methods and the same level of rigor, and structured around a theory of how the system under study works.

My research on chemically stressed populations employs both theoretical and experimental approaches and is a natural extension of my basic research in the area of physiologically structured population models. Key components of this research include the relationship between individual-level and population-level effects of stressors, and methods for quantifying and predicting effects of chemical mixtures from known effects of constituent compounds.

My work on landcover- and landuse-derived stressors on stream health is related to my interest in predicting effects of chemical stressors. Several colleagues and I are developing alternative modeling approaches for routing stressors such as sediment and nutrients from terrestrial source areas to streams and then to watershed outlets. Stressor loads or concentrations can then be predicted at any location in a stream network, and stressor-response modeling techniques can be used to predict impacts on components of stream health, such as various indexes of ecological integrity based on periphyton, macroinvertebrate, and fish assemblages.

My research on the ecology and control of invasive plants involves rigorous, experimentally based assessment of management techniques, as well as empirical and theoretical studies of factors determining the rate of spatial spread of an invading population. Several colleagues and I recently completed a four-year study of Japanese knotweed (Polygonum cuspidatum) and Norway maple (Acer platanoides) invasions of riparian and upland natural areas in Philadelphia's urban parks.

Araujo, A. and McNair, J.N. 2007. Individual- and population-level effects of antimicrobials on the rotifers, Brachionus calyciflorus and B. plicatilis. Hydrobiologia 593: 185–199.

Johnson, T.E., McNair, J.N., Srivastava, P., and Hart, D.D. 2007. Stream ecosystem responses to spatially variable landcover: a model for developing riparian restoration strategies. Freshwater Biology 52: 680–695.

O’Connor, M.P., Agosta, S.J., Hansen , F., Kemp, S.J., Sieg, A.E., McNair, J.N. and Dunham, A.E. 2007. Phylogeny, regression, and the allometry of physiological traits. American Naturalist 170: 431–442.

O’Connor, M.P., Agosta, S.J., Hansen , F., Kemp, S.J., Sieg, A.E., Wallace, B.P., McNair, J.N. and Dunham, A.E. 2007. Size, selection, and physiology: Reconsidering the mechanistic basis of the metabolic theory of ecology. Oikos 116: 1058–1072.

McNair, J.N. 2006. Probabilistic settling in the Local Exchange Model of turbulent particle transport. Journal of Theoretical Biology 241: 420–437.

Srivastava, P., McNair, J.N., and Johnson, T.E. 2006. Comparison of process-based and artificial neural network approaches for streamflow modeling in an agricultural watershed. Journal of the American Water Resources Association 42: 545–563.

Fingerut, J.T., Hart, D.D. and McNair, J.N. 2006. Silk use enhances benthic invertebrate settlement. Oecologia 150: 202–212.

Bram, M.R. and McNair, J.N. 2004. Seed germinability and its seasonal onset in three populations of Japanese knotweed. Weed Science 52: 759–767.

McNair, J.N., and Newbold, J.D. 2001. Turbulent transport of suspended particles and dispersing benthic organisms: the hitting-distance problem for the Local Exchange Model. Journal of Theoretical Biology 209: 351–369.

McNair, J.N. 2000. Turbulent transport of suspended particles and dispersing benthic organisms: the hitting-time distribution for the Local Exchange Model. Journal of Theoretical Biology 202: 231–246.

Goulden, C.E., Moeller, R.E., McNair, J.N., and Place, A.R. 1999. Lipid dietary dependencies in zooplankton. Pages 91–108 in: Arts, M.T. and Wainman, B.C. (Eds.) Lipids in Freshwater Ecosystems. New York: Springer-Verlag.

McNair, J.N., Boraas, M.E., and Seale, D.B. 1998. Size-structure dynamics of the rotifer chemostat: a simple physiologically structured model. Hydrobiologia 387/388: 469–476.

Boraas, M.E., Seale, D.B., Boxhorn, J.E., and McNair, J.N. 1998. Rotifer size distribution changes during transient phases in open cultures. Hydrobiologia 387/388: 477–482.

McNair, J.N., Newbold, J.D., and Hart, D.D. 1997. Turbulent transport of suspended particles and dispersing benthic organisms: how long to hit bottom? Journal of Theoretical Biology 188: 29–52.

McNair, J.N. 1995. Ontogenetic patterns of density-dependent mortality: contrasting stability effects in populations with adult dominance. Journal of Theoretical Biology 175: 207–230.

McNair, J.N., Goulden, C.E., and Ziegenfuss, M.C. 1995. Is there a place for ecotoxicology? Setac News 15: 18–21.

McNair, J.N. and Goulden, C.E. 1991. The dynamics of age-structured populations with a gestation period: density-independent growth and egg ratio methods for estimating the birth rate. Theoretical Population Biology 39: 1–29.

McNair, J.N. 1989. Stability effects of a juvenile period in age-structured populations. Journal of Theoretical Biology 137: 397–422.