People | Mark E. Warner

• B.S., Zoology, University of Georgia, 1992.
• Ph.D., Ecology, University of Georgia, 1998.

The physiological ecology of marine algae, algal-invertebrate symbioses, and the biochemical and molecular maintenance and regulation of photosynthesis in relation to changing environmental conditions.

Coral bleaching

Many reef-building corals contain endosymbiotic algae of the genus Symbiodinium, commonly called zooxanthellae. These algae provide a substantial amount of energy to the coral from translocation of photosynthetically fixed carbon. The past two decades has been a time of unprecedented coral bleaching, when corals loose significant numbers of these algae during physical stress. Cellular mechanisms that lead to bleaching are now currently investigated in my laboratory, with an emphasis on understanding how thermal stress effects the light reactions of photosynthesis. Current analyses include investigating the stability and repair of photosystem II (PSII), from measurements that probe a number of indices from gene transcription to protein stability and the biophysics of energy transfer via chlorophyll fluorescence.

Comparing algal diversity to physiology

Our current knowledge of the phylogeny and distribution of symbiotic dinoflagellates is growing rapidly, yet much less is known with regards to the physiological forces that may influence the ecological distribution of these algae within a single species of coral as well as across an entire reef system. We are currently investigating the physiology of several lineages of symbiotic dinoflagellates in the context of photosynthetic productivity and maintenance as well as the stability of their symbiotic relationship with particular host coral species. Currently funded research projects are underway in the Florida Keys, Bahamas, western Caribbean, and the eastern Pacific.

Photobiology of harmful algal blooms

There has been a dramatic rise in the marine phenomena known commonly as harmful algal blooms (HABs) in coastal waters of the US. While anthropogenic influence has been postulated as a major factor involved in many HABs (e.g. coastal eutrophication), a thorough understanding of what causes the formation and resilience of many blooms has remained elusive. My laboratory is investigating the photobiology of several species of microalgae found in Delaware waters in order to understand how changes in several factors including light, temperature, and nutrient status may affect the balance between photosynthesis, growth, and potential photon damage. Such alterations could lead to significant shifts in the competitive ability of these algae.

The Influence of rising CO₂ on the physiological ecology of microalgae

Atmospheric carbon dioxide is predicted to more than double in the next 100 years, and CO₂ emissions are thus rapidly acidifying the surface ocean with unknown consequences for many marine organisms. At the same time, over the next 50-100 years greenhouse warming is predicted to increase average sea surface temperatures by as much as 4°C. In collaboration with several other researchers, we are currently investigating the physiological impact of future increases in CO₂ and temperature in a wide array of microalgae, including local harmful blooming dinoflagellates and raphidophytes in Delaware, as well as the globally important cyanobacteria, Synechococcus, Prochlorococcus, and Trichodesmium and the coccolithophorid Emiliania huxleyi.

• Dr. Sebastian Hennige, postdoctoral fellow (PhD, University of Essex, 2009)
• Matt Aschaffenburg, Ph.D. student (B.S., Colby College, 2006) 
• Mike McGinley, Ph.D. student  (B.S., Pennsylvania State University, 2005) 
• Lauren Salvitti, M.S. student (B.A., Goucher College, 2006) 
• Leslie Irwin, M.S. student (B.S., Susquehanna University, 2009)

I am currently recruiting students. If you are interested in finding out more about my research program, please contact me.

MAST 200: Introduction to the Oceans
MAST 667: Algal Ecological Physiology
MAST 821: Marine Biosciences Seminar
MAST 827: Ecology and Evolution of Coral Reefs

Manzello, D., Warner, M., Stabenau, E., Hendee, J., Lesser, M., and M. Jankulak. 2009. Remote monitoring of chlorophyll fluorescence in two reef corals during the 2005 bleaching event at Lee Stocking Island, Bahamas. Coral Reefs. In press.

Hennige, S.J., Suggett, D.J., Warner, M.E., McDougall, K.E., and D.J. Smith. 2009. Photobiology of Symbiodinium revisited: bio-physical and bio-optical signatures. Coral Reefs. In press.

Morgan-Kiss, R.M., Chan, L-K., Modla, S., Weber, T.S., Warner, M., Czymmek, K.J., and T.E. Hanson. 2008. Chlorobaculum tepidum regulates chlorosome structure and function in response to temperature and electron donor availability. Photosynthesis Research. In press.

Fei-Xue, F., Margaret, M.R., Garcia, N., Beck, A., Bernhardt, P.W., Warner, M.E., Sanudo-Wilhelmy, S.A., and D.A. Hutchins. 2008. Interactions between changing pCO₂, N₂ fixation, and Fe limitation in the marine unicellular cyanobacterium Crocosphaera. Limnology and Oceanography. 53: 2472–2484.

Handy, S.M., Demir, E., Hutchins, D.A., Portune, K.J., Whereat, E.B., Hare, C.E., Rose, J.M., Warner, M., Farestad, M., Cary, S.C., and K.J. Coyne. 2008. Using quantitative real-time PCR to study competition and community dynamics among Delaware Inland Bays harmful algae in field and laboratory studies. Harmful Algae. 7: 599–613.

Suggett, D.J., Warner, M.E., Smith, D.J., Davey, P., Hennige, S., and N.R. Baker. 2008. Photosynthesis and production of hydrogen peroxide by Symbiodinium (Pyrrhophyta) phylotypes with different thermal tolerances. Journal of Phycology. 44: 948–956.

LaJeunesse, T.C., Reyes-Bonilla, H., Warner, M.E., Wills, M., Schmidt, G.W., and W.K. Fitt. 2008. Specificity and stability in high latitude eastern Pacific coral-algal symbioses. Limnology and Oceanography. 53: 719-727.

Feng, Y., Warner,M.E., Zhang, Y., Sun, J., Fu, F.-X., Rose, J.M., and D.A. Hutchins. 2007. Interactive efffects of increased pCO₂, temperature, and irradiance on the marine coccolithophore Emiliania huxleyi (Prymnesiophyceae). European Journal of Phycology. 43: 87-98.

Fu, F.-X., Zhang, Y., Warner, M.E., Feng, Y., Sun, J., and D.A. Hutchins. 2007. A comparison of future increased CO₂ and temperature effects on sympatric Heterosigma akashiwo and Prorocentrum minimum. Harmful Algae. In press.

Hutchins, D.A, Fu, F.-X.,  Zhang, Y., Warner, M.E., Feng, Y., Portune, K., Bernhardt, P.W., and M.R. Mulholland. 2007. CO₂ control of Trichodesmium N₂ fixation, photosynthesis, growth rates, and elemental ratios: Implications for past, present, and future ocean biogeochemistry. Limnology and Oceanography. 52: 1293-1304. 

Fu, F.-X., Warner, M.E., Zhang, Y., Feng, Y., and D.A. Hutchins. 2007.  Effects of increased temperature and CO₂ on photosynthesis, growth and elemental ratios in marine Synechococcus and Prochlorococcus (Cyanobacteria). Journal of Phycology. 43: 485-496.

LaJeunesse, T.C., Reyes-Bonilla, H., and M.E. Warner. 2007. Spring 'bleaching' among Pocillopora in the Sea of Cortez, Eastern Pacific. Coral Reefs. 26: 265-270.

Popels, L., MacIntyre, H., Warner, M., Zhang, Y., and D. Hutchins. 2007. Physiological responses during dark survival and recovery in Aureococcus anophagefferens (Pelagophyceae). Journal of Phycology. 43: 32-42.

Warner, M.E. and M.L. Madden. 2006. The impact of shifts to elevated irradiance on the growth and photochemical activity of the harmful algae Chattonella subsalsa and Prorocentrum minimum from Delaware. Harmful Algae. 6: 332-342.

Warner, M.E. and S. Berry-Lowe. 2006. Differential xanthophyll cycling and photochemical activity in symbiotic dinoflagellates in multiple locations of three species of Caribbean coral. Journal of Experimental Marine Biology and Ecology. 339: 86-95.

Warner, M.E., LaJeunesse, T.C., Robison, J.D., and R.M. Thur. 2006. The ecological distribution and comparative photobiology of symbiotic dinoflagellates from reef corals in Belize: Potential implications for coral bleaching. Limnology and Oceanography. 51: 1887-1897.

Robison, J.D. and M.E. Warner. 2006. Differential impacts of photoacclimation and thermal stress on the photobiology of four different phylotypes of Symbiodinium (Pyrrhophyta). Journal of Phycology. 42: 568-579.

Pustizzi, F., MacIntyre, H., Warner, M.E., and D.A. Hutchins. 2004. Interaction of nitrogen source and light intensity on the growth and photosynthesis of the brown tide alga Aureococcus anophagefferens. Harmful Algae. 3: 343-360.

Yellowlees, D. and M.E. Warner. 2003. Photosynthesis in symbiotic algae. Photosynthesis in Algae. Eds. Larkum, Douglas, and Raven. Kluwer Academic. 14: 437-455.

Warner, M.E., Chilcoat, G., McFarland, F., and W.K. Fitt. 2002. Seasonal fluctuations in the photosynthetic capacity of photosystem II in symbiotic dinoflagellates within the Caribbean reef-building coral Montastraea. Marine Biology. 141:31-38.

Fitt, W.K., Brown, B.E., Warner, M.E., and R.P. Dunne. 2001. Coral bleaching: inte

• Matilda Madden, (M.S., University of Delaware, College of Marine Studies, 2005)
• Jennifer Robison, (M.S., University of Delaware, College of Marine and Earth Studies, 2006)