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Richard Horowitz

Richard Horwitz, PhD

Associate Professor, Department of Biodiversity, Earth & Environmental Science
Senior Scientist, Fisheries Section Leader, Ruth Patrick Chair of Environmental Sciences, Academy of Natural Sciences of Drexel University
Department of Biodiversity, Earth and Environmental Science
Office: Patrick Center, Academy of Natural Sciences
Phone: 215.299.1092

Additional Sites: Fisheries Group


  • BS, Biology, Cornell University, 1971
  • PhD, Evolutionary Biology, The University of Chicago, 1976

Research Interests:

My primary focus is the ecology of freshwater and estuarine fishes. I am interested in factors controlling the abundance and distribution of stream fishes. Such factors include historical and ecological effects, as well as recent human influences, such as changes in hydrology, connectivity, and watershed conditions. For example, I am currently using molecular genetics to assess regional and fine-scale population structure of a rare minnow. The genetic structure reflects long term effects of glaciation, drainage evolution and recolonization, as well as recent effects of population fragmentation due to habitat degradation. I have been part of project teams in a number of studies of the effects of riparian vegetation, dams and dam removals, watershed development, point and non-point source contamination and other factors on stream biota, chemistry, and geomorphology.


Richard Horwitz, PhD is the Fisheries Section Leader in the Patrick Center for Environmental Research at the Academy of Natural Sciences of Drexel University. He currently occupies the Ruth Patrick Chair in Environmental Research. He has also been the leader of the Biometry Section within the Patrick Center. He has extensive experience studying freshwater and estuarine fishes in the Eastern United States, and has also conducted fish surveys in Peru and Nepal. In addition to projects mentioned under research focus, he has studied the effects of B.t.i., a biological control for black flies, on fishes, participated in watershed management planning in New York, and led the preparation of a master plan for ecological restoration of Fairmount Park.

Selected Publications:

  • Horwitz, R.J. T.E. Johnson, P.F. Overbeck, T. Kevin O’Donnell, W. C. Hession and B.W. Sweeney. 2008. Effects of riparian vegetation and land use on fishes in mid-Atlantic streams. J. American Water Resources Assoc.44:724-741.
  • Flinders, C.A., R.J. Horwitz, and T. Belton. 2008. Relationship of fish and macroinvertebrate communities in the mid-Atlantic uplands: implications for integrated assessments. Ecological Indicators. 8:588-598.
  • Hession, C.W., J. Pizzuto, T. Johnson, R. Horwitz and B. Sweeney. 2003. Influence of bank vegetation on channel morphology in rural and urban watersheds. Geology 31(1):147-150.
  • Jackson, J.J. and R.J. Horwitz. 2002. Effects of Bacillus thuringiensis israelensis in black flies and nontarget macroinvertebrates and fish in a large river. Transactions of the American Fisheries Society 131: 910-930.
  • Horwitz, R.J. , B.W. Thompson, C. Cianfrani, N.C. Coulter, W.C. Hession, J.E. Pizzuto, A. Rhoads, and A.E. Schuyler. 1999-2001 Master Plan for Natural Lands Restoration in Fairmount Park, Philadelphia. Three Volumes.
  • Fairchild, G.M., R.J. Horwitz, D.A. Nieman, M.R. Boyer and D.F. Knorr. 1998 Effects of habitat quality, and historical change, on fish communities of the Schuylkill River drainage, southeast Pennsylvania. American Midland Naturalist 139:282-295.