John D. Wehr


John Wehr, Department of Biological Sciences, Calder Center
Department of Biological Sciences
Fordham University
Larkin Hall - 100B
441 East Fordham Road
Bronx, NY 10458

Louis Calder Center
53 Whippoorwill Rd., Box 887
Armonk, NY 10504

Phone: 914-273-3078, ext. 11
Fax: 914-273-2167


BS - Biology, Northern Arizona University
MS - Botany, University of British Columbia
PhD - Botany, University of Durham

Research Opportunities

Algal Biodiversity, Ecosystem Function and Bioassessment in Streams and Rivers

We are conducting an ecoregion survey of freshwater algae across New York State. Our aims are to catalog the New York algal diversity, assess the influence of ecological conditions that favor or threaten biodiversity, and establish a GIS database to identify geographic and ecological trends. With these data we aim to examine how algal diversity affects ecosystem services, such as primary productivity, CO2 absorption, decomposition, and nutrient cycling in streams.

Ecological Stoichiometry and Nutritional Ecology of Benthic Algae in Streams

We have been questioning the current paradigm that allochthonous matter –terrestrial and detrital carbon sources – is of primary importance to stream consumers. We are investigating quantitative and qualitative differences between terrestrial (e.g. forest leaves) and aquatic (algae and bryophytes) food sources. Algae offer significantly greater P (lower C:P ratios) and N (lower C:N ratios) than detritus sources, and have substantially richer supply of essential fatty acids required by invertebrate consumers. Current work is focusing on both benthic and transported matter and the relative importance of aquatic and detrital matter in these fractions.

Dynamics and Role of Phytoplankton Communities in Large Rivers

Research on phytoplankton in large rivers has had a long history, yet their importance in these enormous ecosystems is still not well known or appreciated. Our work began with longitudinal studies on a geologically restricted, 360 km long region of the Ohio River, and examined the effects of navigation (“low-head”) dams, tributaries and littoral zones on the abundance and species composition of phytoplankton. We have begun collaborating with scientists at the US Geological Survey in La Crosse, Wisconsin to examine factors affecting phytoplankton production in the upper Mississippi River, using a 10-year sample program coupled with data on discharge, nutrient conditions, backwaters, and other landscape variables.

Ecology, Classification and Biogeography of Freshwater Brown Algae

The Phaeophyceae is a large and diverse class of algae, but less than one percent of the species occur in freshwater environments. We are investigating the genetic relationships among these taxa using 18S rDNA SSU and rbcL information. We are currently examining the origin and speciation of freshwater browns, and their likely invasion from marine environments. Some species have clear (recent and ancient) origins in marine environments, yet little is known of the rate of their invasions and ecological or genetic adaptations. Others have no close marine relatives. A combination of biogeographic and molecular studies seems the likely approach to these questions.

Selected Publications

Copies are available for articles indicated by the links.

Feel free to contact me ( if you have any questions about our work.

  1. Wehr, J.D. 1981. Analysis of seasonal succession of attached algae in a mountain stream, the North Alouette River, British Columbia. CanJ Botany 59: 1465-1474.

  2. Wehr, J.D., Say. P.J. & Whitton, B.A. 1981. Heavy metals in an industrially polluted river, the Team. pp. 99-107. In: Heavy Metals in Northern England: Environmental and Biological aspects. P.J. Say & B.A. Whitton (eds.), University of Durham Press, England.

  3. Whitton, B.A., Say, P.J. & Wehr, J.D. 1981. Use of plants to monitor heavy metals in rivers. pp. 125-145. In: Heavy Metals in Northern England: Environmental and Biological aspects. P.J. Say & B.A. Whitton (eds.), University of Durham Press, England.

  4. Wehr, J.D. & Whitton, B.A. 1983. Aquatic cryptogams of natural acid springs enriched with heavy metals: the Kootenay Paint Pots, British Columbia. Hydrobiologia 98:97-105.

  5. Wehr, J.D., Empain, A., Mouvet, C., Say, P.J. & Whitton, B.A. 1983. Methods for process­ing aquatic mosses used as monitors of heavy metals. Water Res 17: 985-992.

  6. Wehr, J.D. & Whitton, B.A. 1983. Accumulation of heavy metals by aquatic mosses. 2. Rhynchostegium riparioides. Hydrobiologia 100: 261-284.

  7. Wehr, J.D. & Whitton, B.A. 1983. Accumulation of heavy metals by aquatic mosses. 3. Seasonal changes. Hydrobiologia 100: 285-291.

  8. Wehr, J.D., & Stein, J.R. 1985. Studies on the autecology and biogeography of the freshwater brown alga Heribaudiella fluviatilis (Aresch.) Sved. Journal of Phycology 21: 81-93.

  9. Wehr, J.D., Brown, L.M. & O'Grady, K, 1985. Physiological ecology of the bloom-forming alga Chrysochromulina breviturrita Nich. (Prymnesiophyceae) from lakes influenced by acid precipitation. Can J Botany 67: 2231-39.

  10. Wehr, J.D. & Brown, L.M. 1985. Selenium requirement of a bloom-forming planktonic alga from softwater and acidified lakes. Can J Fish Aquat Sci 42: 1783-1788.

  11. Wehr, J.D. & Brown, L.M. 1986. Hydrogen ion buffering of culture media for algae from moderately acidic, oligotrophic waters. J Phycology 22: 88-94.

  12. Brown, L.M. and Wehr, J.D. 1986. Development of selenium analysis methodology at ng/L levels for soft waters subject to acidic precipitation. Proc Technol Transfer Conf 7: 97-110.

  13. Wehr, J.D. and Whitton, B.A. 1986. Ecological factors relating to morphological variation in the aquatic moss Rhynchostegium riparioides. J Bryology 14: 269-280.

  14. Wehr, J.D., Brown, L.M. & O'Grady, K. 1987. Highly specialized nitrogen metabolism in a freshwater phytoplankter, Chrysochromulina breviturrita. Can J Fish Aquat Sci 44: 736-742.

  15. Wehr, J.D., Kelly, M.G. & Whitton, B.A. 1987. Factors affecting accumulation and loss of zinc by the aquatic moss Rhynchostegium riparioides (Hedw.) C. Jens. Aquat Bot 29: 261-274.

  16. Wehr, J.D. 1989. Experimental tests of nutrient limitation in freshwater picoplankton. Appl Environ Microbiol 55: 1605-1611.

  17. Wehr, J.D. 1990. Predominance of picoplankton and nanoplankton in eutrophic Calder Lake. Hydrobiologia 203: 35-44.

  18. Wehr, J.D. 1991. Nutrient- and grazer-mediated effects on picoplankton and size structure in phytoplankton communities. Int Rev Ges Hydrobiol 76: 643-656.

  19. Toolan, T., Findlay, S., & Wehr, J.D. 1991. Inorganic phosphorus stimulation of bacterio­plankton production in a meso-eutrophic lake. Applied and Environmental Microbiology 57: 2074-2078.

  20. Samaritan, J.M., J.D. Wehr, A. Buccafuri, & M. Sahn. 1992. Automated measurement of aque­ous aluminum by the pyrocatechol violet method. International Journal of Environmental Analytical Chemistry 50: 173-182.

  21. Wehr, J.D. 1992. Effects of experimental manipulations of light and phosphorus supply on competition among picoplankton and nanoplankton in an oligotrophic lake. Can J Fish Aquat Sci 50: 936-945.

  22. Wehr, J.D. 1993. [Review of] Progress in phycological research, Volumes 7 and 8. J Appl Phycol 5: 477-480.

  23. Wehr, J.D. J. Le, & Campbell, L 1994. Does microbial biomass affect pelagic ecosystem efficiency? An experimental study. Microb Ecol 27: 1-17.

  24. Le, J., J.D. Wehr, & Campbell, L. 1994. Uncoupling of bacterioplankton and phytoplankton production in fresh waters is affected by inorganic nutrient limitation. Appl Environ Microbiol 60: 2086-2093.

  25. Thorp, J.H., A.R. Black, K.H. Haag, & J.D. Wehr. 1994. Zooplankton assemblages in the Ohio River: seasonal, tributary, and navigation dam effects. Can J Fish Aquat Sci 51: 1634-1643.

  26. Wehr, J.D. & J.H. Thorp. 1997. Impacts of navigation dams, tributaries and littoral zones on phytoplankton communities in the Ohio River. Can J Fish Aquat Sci 54: 378-395.

  27. Wehr, J.D., S.P. Lonergan,& J.H. Thorp. 1997. Concentrations and controls of dissolved organic matter in a constricted-channel region of the Ohio River. Biogeochemistry 38: 41 – 65.

  28. Wehr, J.D. & Descy, J.-P. 1998. Use of phytoplankton in large river management. Journal of Phycology 34: 741-749.

  29. Wehr, J.D., Holen, D.A. MacDonald, M.M.& Lonergan, S.P. 1998. Effects of different carbon sources on a freshwater plankton community. Can. J. Fish. Aquat. Sciences 55: 2150-2160.

  30. Wehr, J.D., Petersen, J., & Findlay, S. 1999. Influence of three contrasting detrital carbon sources on planktonic bacterial metabolism in a mesotrophic lake. Microb Ecol 37: 23-35.

  31. Wigand, C., Wehr, J.D., Limburg, K., Gorham, B., Lonergan, S., & Findlay, S. 2000. Effect of Vallisneria americana on community structure and ecosystem function in lake mesocosms. Hydrobiologia 418: 137-146.

  32. Wehr, J.D. 2002. Phylum Phaeophyta. In: John, D., A.J. Brook, & B.A. Whitton [Eds.], Freshwater Algal Flora of the British Isles, Cambridge Univ. Press; pp. 278-280. [ISBN 0-521-77051-3]

  33. Sheath, R.G, & Wehr, J.D. 2003. Introduction to Freshwater Algae, pp. 1-9, In: Freshwater Algae of North America: Ecology and Classification. Academic Press, San Diego, CA. [ISBN 0-12-741550-5]

  34. Wehr, J.D. & Sheath, R.G. 2003. Freshwater Habitats of Algae. pp. 11-57, In: Freshwater Algae of North America: Ecology and Classification. Academic Press, San Diego, CA. [ISBN 0-12-741550-5]

  35. Wehr, J.D. 2003. Brown Algae. pp. 757-773, In: Freshwater Algae of North America: Ecology and Classification. Academic Press, San Diego, CA. [ISBN 0-12-741550-5]

  36. Wehr, J.D. & A.A. Perrone. 2003. A new record of Heribaudiella fluviatilis, a freshwater brown alga (Phaeophyceae) from Oregon. Western North Am Naturalist.63: 517-523.

  37. Huss, A.A. & Wehr, J.D. 2004. Strong indirect effects of a submersed aquatic macrophyte, Vallisneria americana, on bacterioplankton densities in a mesotrophic lake. Microb Ecol 47: 305-315.

  38. Kostel-Hughes, F., T. P. Young, and J. D. Wehr. 2005. Effects of leaf litter depth on the emergence and seedling growth of deciduous forest tree species in relation to seed size. Journal of the Torrey Botanical Society 132:50-61.

  39. Wehr, J.D. 2007. [Review of] Algae: Anatomy, Biochemistry and Biotechnology, by L. Barsanti & P. Gualtieri. (CRC Press). Journal of Phycology 43: 412-414.

  40. McCauley, L. A. R., and J. D. Wehr. 2007. Taxonomic reappraisal of the freshwater brown algae Bodanella, Ectocarpus, Heribaudiella, and Pleurocladia (Phaeophyceae) on the basis of rbcL sequences and morphological characters. Phycologia 46:429-439. (DOI: 10.2216/05-08.1)

  41. Torres-Ruiz, M., J. D. Wehr, and A. A. Perrone. 2007. Trophic relations in a stream food web: importance of fatty acids for macroinvertebrate consumers. Journal of the North American Benthological Society 26:509-522.

  42. O'Brien, P.J. & Wehr, J.D. 2009. Periphyton biomass and ecological stoichiometry in streams within an urbanto rural land-use gradient. Hydrobiologia.

  43. Torres-Ruiz, M., Wehr, J.D. & Perrone, A.A. 2010. Are net-spinning caddisflies what they eat? An investigation using controlled diets and fatty acids. Journal of the North American Benthological Society 29: 803-813.

  44. Torres-Ruiz, M., & Wehr, J.D.2010. Changes in the nutritional quality of decaying leaf litter in a stream based on fatty acid content. Hydrobiologia 651: 265-278.

  45. Wehr, J.D. 2010. Xanthophyta and Phaeophyta, pp. 271-287, in: Algae: Source to Treatment Manual of Water Supply Practices M57. American Water Works Association, Denver, CO. [ISBN 978-1-58321-787-0].

  46. Wehr, J.D. 2011. Phylum Phaeophyta (Brown Algae). In: John, D., A.J. Brook, & B.A. Whitton [Eds.], Freshwater Algal Flora of the British Isles, Second Edition, Cambridge University Press, U.K.

  47. Gabel, K.W. Wehr, J.D., & Truhn, K.M. 2012. Assessment of the effectiveness of best management practices for streams draining agricultural landscapes using diatoms and macroinvertebrates. Hydrobiologia 680: 247-264. (DOI 10.1007/s10750-011-0933-8).

  48. Wehr, J. 2012. Benthic cyanobacteria in streams of New York State, USA. Chapter 32, In: Ecology of Cyanobacteria II. Their Diversity in Space and Time. 2nd ed. Whitton BA (ed.), Springer, Dordrecht.

  49. Wehr, J.D., Stancheva, R., Sheath, R.G., Truhn, K. 2013. Discovery of new populations of the rare freshwater brown alga Pleurocladia lacustris A. Braun in California streams. Western North American Naturalist 73: 148-157.

  50. Cashman, M.J., Wehr, J.D., Truhn, K. 2013. Elevated light and nutrients alter the nutritional quality of stream periphyton. Freshwater Biology 58: 1447-1457. (DOI: 10.1111/fwb.12142).


Wehr, J.D. & Sheath, R.G. [Eds.] 2003. Freshwater Algae of North America: Ecology and Classification. Academic Press, San Diego, CA. 950 pp.