Sujan M. Henkanaththegedara
Degree Program: Ph.D. in Environmental and Conservation Sciences
Major Advisor: Dr. Craig Stockwell
Office/Lab: Stevens 105
B.S., Zoology. University of Kelaniya, Sri Lanka (2004)
Thesis research: Investigation of species diversity of aquatic birds in seasonal reservoirs in Anuradhapura and Monaragala districts, Sri Lanka.
- Ecological interactions between native and non-native fish
- Evolutionary ecology of life history evolution in fish
- Systematics and ecology of native desert fish in south-western USA
Thesis/ Dissertation Research
My dissertation research is focused on ecological interactions between endangered Mohave tui chub (Siphateles bicolor mohavensis) and non-native western mosquitofish (Gambusia affinis). Mohave tui chub is a native cyprinid fish species in southern California. This species is listed as an endangered species federally and in state of California mainly due to its restricted range and possible impacts of non-native species. Two of four existing populations of Mohave tui chubs have been contaminated by non-native western mosquitofish. Local eliminations and population reductions of native fish species have been reported after introduction of mosquitofish in to non-native habitats. The mechanisms of elimination of native fish species by mosquitofish are associated with resource competition or by predating eggs, larvae, young or even adult fish. Primary goal of my research is to evaluate the possible impacts of mosquitofish on Mohave tui chubs. We conducted a series of mesocosm experiments (2007-09) to evaluate any possible impacts of mosquitofish on Mohave tui chub larval survival and body growth. We hypothesized that there are negative impacts of mosquitofish on Mohave tui chub larval survival via predation on chub eggs/larvae and body growth via resource competition. In contrary to our hypotheses, we failed to detect a significant difference on the average number of chub larvae produced between control and treatment. Further the mean instantaneous growth rate of individual chubs was significantly higher in the presence of mosquitofish compared to the control. Interestingly, mosquitofish populations declined significantly in treatment. This suggested that Mohave tui chub may predate on mosquitofish. Continuing laboratory experiments are focused on studying the predatory interactions between Mohave tui chubs and mosquitofish. Any life history trait evolution of this reciprocal predaor-prey system will also be investigated.
Awards and Honors
2008 Outstanding Ph.D. student Award, Department of Biological Sciences, North Dakota State University
2008 Bob Adams Memorial Award for best student oral presentation, 23rd Annual Desert Symposium, Desert Studies Center, California State University, California, 18-21 April.
2008 Best Oral Presentation, Fifth Annual Northern Plains Biological Symposium, Skills and Technology Training Center, North Dakota State University, Fargo, 11 April.
2004 Gold medal for the best performance in B.S. Zoology degree, Alumni Association of the Faculty of Science, University of Kelaniya, Sri Lanka.
- Stockwell, C.A. and S.M. Henkanaththegedara (In Review) Evolutionary conservation biology of Poeciliids. In. Evan, J., A. Pilastro and I. Schlupp (editors). Ecology and Evolution of Livebearing Fishes (Poeciliidae). 2nd Edition.
- Henkanaththegedara, S.M., B.J. Herath and D.J.A. Korala. 2006. Butterfly fauna of Bellanwila-Attidiya sanctuary and its environs, Sri Lanka Naturalist. 7 (1 and 2): 1-8.
- Maduranga, H.G.S. 2005. Ichthyofauna of Bellanwila-Attidiya sanctuary and its environs in Colombo, Sri Lanka. Tigerpaper. FAO. 32: 26-32.
- Jayaneththi, H.B. and H.G.S. Maduranga. 2004. A Preliminary Study on the diversity of Ichthyofauna of Kukulugala Proposed Forest Reserve, Ratnapura District. Sri Lanka Naturalist 6(1&2): 17-23.
- Maduranga, H.G.S. 2004. A new record of the White wagtail Motacilla alba Sykes from Wellawaya, Monaragala district. Sri Lanka Naturalist. 6(1 and 2): 15-16.
- Maduranga, H.G.S. 2003. Endemic freshwater fishes of Sri Lanka (Sirilaka awenika miridiya mason in Sinhala). Department of National Zoological Gardens, Sri Lanka. 108 pp. (ISBN 955-8513-03-2)
- Maduranga, H.G.S. 2002. Evidence of nesting of Wooly-necked Stork Ciconia episcopus episcopus (Boddaert) near human habitation in Sri Lanka. Sri Lanka Naturalist. 5(3 and 4): 50-52.
- Henkanaththegedara, S.M. 2002. Sharp-tailed Sandpiper Calidrias acuminate (Horsefield) 1821; A sight record at Maha Lewaya, Hambantota district. Sri Lanka Naturalist. 5(1): 8-10.
- Henkanaththegedara, S.M., S. Jayaweera and N. Perera. 2001. A new record of Red neck Goby Schismatagobius deraniyagalai Kottelet & Pethiyagoda, 1991 from Bentota river basin. Sri Lanka Naturalist. 4(1): 14-17.
- Henkanaththegedara, S.M. and B.J. Herath. 2000. Notes on the Glossy Ibis Plegadis falcinellus (Linn.). Sri Lanka Naturalist. 3(2): 23-28.
- Maduranga, H.G.S. and U.S. Amarasinghe. 2004. Species diversity of aquatic birds in seasonal reservoirs in Anuradhapura and Monaragala districts, Sri Lanka. Sri Lanka Association for the Advancement of Science. Colombo, Sri Lanka, December 17-22. Proceedings of 60th Annual Session.
- Henkanaththegedara, S.M. and C.A. Stockwell. 2006. Biotic Evaluation of Mohave tui chub (Siphateles bicolor mohavensis) Habitats, Lake Tuendae and MC Spring, Mojave National Preserve, CA. Desert Fishes Council 62nd Annual Meeting, Death Valley, California, 15-19 November.
- Henkanaththegedara, S.M. and C.A. Stockwell. 2007. Relative effectiveness of horizontal Van Dorn water sampler and vertical tow net in sampling zooplankton. Fourth Northern Plains Biological Symposium. Grand Forks, North Dakota, 14 April.
- Henkanaththegedara, S.M., C.A. Stockwell, S. Parmenter and D.L. Hughson. 2008. Population size and structure of endangered Mohave tui chub (Siphateles bicolor mohavensis) in three habitats, southern California. Fifth Northern Plains Biological Symposium. Skills and Technology Training Center, North Dakota State University, Fargo, North Dakota, 11 April 2008.
- Henkanaththegedara, S.M. 2008. The fish of the Mojave Valley: Current research and recent findings. 23rd Annual Desert Symposium, Desert Studies Center, California State University Zzyzx, California, 18-21 April.
- Hughson, D.L., N. Darby, J. Dungan, S. Henkanaththegedara, B. Hilborn, J. Hohman, and S. Parmenter. 2008. Recovering the endangered Mohave tui chub (Siphateles bicolor mohavensis). 23rd Annual Desert Symposium, Desert Studies Center, California State University, Zzyzx, California, 18-21 April.
- Henkanaththegedara, S.M and C. Stockwell. 2008. Impacts of mosquitofish, Gambusia affinis on endangered Mohave tui chub, Siphateles bicolor mohavensis growth and population dynamics: A mesocosm study approach. 40th Annual Meeting of the Desert Fishes Council. Cuatro Cienegas, Coahuila, Mexico, November 12-16.
- Henkanaththegedara, S. M., W. Clark and C.A. Stockwell. 2008. Precision of aging of endangered Mohave tui chub (Siphateles bicolor mohavensis) using scales and three different hard structures. Annual meeting of Minnesota Chapter of American Fisheries Association, Holiday Inn Hotel and Suites, Alexandria, Minnesota, 3-5 March (POSTER)
- Henkanaththegedara, S.M., J. Seigel, D. Hughson, S. Parmenter, M. Huffine and C. Stockwell. 2008. Freshwater fishes of Mojave River, California: past and present. 40th Annual Meeting of the Desert Fishes Council. Cuatro Cienegas, Coahuila, Mexico, November 12-16 (POSTER)