Ph.D., University of Miami Rosenstiel School of Marine and Atmospheric Science (RSMAS), 1996

Primary productivity of tropical marine ecosystems Climate change (elevated temperature, salinity and pCO2) effects on tropical marine autotrophs Stress responses and adaptation to stress in tropical marine autotrophs (macroalgae, seagrass, mangrove) Biogeochemistry and nutrient cycling in tropical carbonate ecosystems

Our research is on nutrient cycling and primary production in tropical marine ecosystems and stressors that influence tropical seagrass, mangrove and algal communities. We are currently focused on climate change effects, including elevated temperature, salinity and pCO2, termed “ocean acidification”, on marine plant and macroalgal communities. We hypothesize that ocean acidification and elevated temperature affect photosynthesis, growth and calcification in tropical reef macroalgae with far-reaching ecological consequences. However, diverse pathways of inorganic carbon acquisition for photosynthesis and mechanisms of calcification may provide resistance to elevated ocean pCO2 in calcifying macroalgae. In addition, we are elucidating mechanisms causing seagrass mortality in Florida Bay, relevant to lagoons and estuaries world-wide. Our research approach is to examine stress responses from the physiological and ecological scale, consider species life history, and focus on ecosystem-level indicators of stress, such as hypoxia and eutrophication. We are also interested in biogeochemical changes that can destabilize foundation plant communities and thereby influence the sustainability of marine ecosystems. The majority of our work is in shallow tropical carbonate environments (lagoons and reefs) of South Florida, The Bahamas and wider Caribbean. We typically take an experimental approach to examine alternative hypotheses in mesocosms and field settings.

Strazisar, T., Koch, M., Madden, C. (2016) The importance of recurrent reproductive events for Ruppia maritima seed bank viability in a highly variable estuary: the Everglades-Florida Bay ecotone. Journal of Aquatic Botany. DOI: 10.1016/j.aquabot.2016.07.005 Hofmann, L.C., Koch, M.S., de Beer, D. (2016) Evidence for biotic control of diffusive boundary layer pH and active Ca2+ flux mechanisms in a tropical crustose coralline alga. PLOS ONE. DOI: 10.1371/journal.pone.0159057 Peach, K.E., Koch, M.S., Blackwelder, P. (2016) Effects of elevated pCO2 and irradiance on growth, photosynthesis and calcification in Halimeda discoidea Marine Ecology Progress Series 01/2016; DOI: 10.3354/meps11591. Koch, M., Bowes, G., Ross, C., Zhang, Xing-Hai. (2013 electronic; 2014 print) Climate change and ocean acidification effects on seagrasses and marine macroalgae. Review paper: Global Change Biology 19, 103–132, DOI: 10.1111/j.1365-2486.2012.02791.x