Education

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

Research Interests

• 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

Research Description

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 to 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 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.

Recent Publications

• Koch, M.S., C. R. Johnson, L. Travis, O. Pedersen, C. J. Madden. (2022)    Hypersalinity    effects on O₂       flux across the diffusive boundary layer of leaves in the tropical seagrass    Thalassia testudinum    Journal of Experimental Marine Biology and Ecology. 555: 1-8. https://doi.org/10.1016/j.jembe.2022.151780.        
• Koch, M.S., C. R. Johnson, C. J. Madden, O. Pedersen. (2022) Low irradiance disrupts the internal O₂       dynamics of seagrass (Thalassia testudinum) leading to shoot meristem H₂S intrusion. Aquatic Botany 181: 1-11. https://doi.org/10.1016/j.aquabot.2022.103532  
• Koch, M.S., C. R. Johnson, C. J. Madden, O. Pedersen. (2022) Irradiance, Water Column O₂       , and Tide Drive Internal O₂       Dynamics and Meristem H₂S Detection in the Dominant Caribbean‐Tropical Atlantic Seagrass,    Thalassia testudinum. Estuaries and Coasts.  https://doi.org/10.1007/s12237-022-01064-y     
• Strazisar, T., Koch, M., Madden, C. (2021) Abiotic and Biotic Interactions Control    Ruppia maritima       Life history development within a heterogeneous coastal landscape. Estuaries and Coasts. 44, pages1975–1993.
• C. McNicholl, M. S. Koch,    Swarzenski, P.W., Oberhaensli, F.R., Taylor A., Gomez Batista, M., Metian M.    (2020) Ocean acidification effects on calcification and dissolution in tropical reef macroalgae. Coral Reefs 39, pages1635–1647 https://doi.org/10.1007/s00338-020-01991-x
• C. McNicholl, M. S. Koch,    Hofmann, L.C.        (2019) Photosynthesis and light-dependent proton pumps increase boundary layer pH in tropical macroalgae: A proposed mechanism to sustain calcification under ocean acidification. Journal Experimental Marine Biology and Ecology. https://doi.org/10.1016/j.jembe.2020.151489 
• Johnson, M. S. Koch, O. Pedersen and C. J. Madden (2020)    Hypersalinity affects leaf and meristem O₂       dynamics exposing meristems to H₂S in the dominant tropical seagrass Thalassia testudinum. Journal Experimental Marine Biology and Ecology. 533:1-10. https://doi.org/10.1016/j.jembe.2020.151458  
• Andersson, A.J, Venn, A.A., Pendleton, L., Brathwaite, A., Camp, E.F., Colley, S. Gledhill, D., Koch, M., Maliki, S., Manfrino, C. 2019. Ecological and socioeconomic strategies to sustain Caribbean coral reefs in a high-CO₂       world. Regional Studies in Marine Science. 29:1-13.   
• Johnson, M. S. Koch, O. Pedersen and C. J. Madden (2018) Hypersalinity as a trigger of seagrass (Thalassia testudinum) die-off events in Florida Bay: Evidence based on shoot meristem O₂       and H₂S dynamics. Journal Experimental Marine Biology and Ecology. 504:47-52. https://doi.org/10.1016/j.jembe.2018.03.007  
• Zweng, R.C., Koch, M.S., Bowes, G. (2018). The role of irradiance and C-use strategies in tropical macroalgae photosynthetic response to ocean acidification.    Scientific Reports       . https://doi.org/10.1038/s41598-018-27333-0     
• Morey, S., Koch, M., Liu, Y., Lee, SK. (2017) Chapter 7 Florida’s Oceans and Marine Habitats in a Changing Climate. In (eds. Chassignet, E., Jones, J., Misra, V., Mitchum, G., Obeysekera) Florida’s Climate: Changes, Variations & Impacts. University Press of Florida, Gainesville, FL.         
• Peach, K.E., Koch, M.S.,    Blackwelder, P.L., Kamasawa, N., Guerrero-Given, D.       (2017)    Primary utricle structure of six    Halimeda       species and potential relevance for ocean acidification tolerance. Botanica Marina 60(1): https://doi.org/10.1515/bot-2016-0055
• Peach, K.E., Koch, M.S., Blackwelder, P.L., Manfrino, C. J. (2016) Calcification and photophysiology responses to elevated    pCO₂       in six    Halimeda       species from contrasting irradiance environments on Little Cayman Island reefs. Exp. Mar. Bio. Ecol. 486, 114-126, https://doi.org/10.1016/j.jembe.2016.09.008     
• 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 https://doi.org/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 https://doi.org/10.1371/journal.pone.0159057     
• Bedwell, H., Joles, L., Koch, M.S., Peach, K., Dutra, E., Manfrino, C. (2016) The role of in hospite zooxanthellae photophysiology and reef chemistry on elevated    pCO₂ effects in two branching Caribbean corals: Acropora cervicornis and Porites divaricata . ICES Journal of Marine Science https://doi.org/10.1093/icesjms/fsw026  
• Koch, M. S. (2016) The significance of warming seas for species and ecosystems: Impacts and effects on seagrasses. In (eds. Laffoley, D., Baxter, J.M.) Explaining Ocean Warming: Causes, scale, effects and consequences. IUCN-International Union for Conservation of Nature and Natural Resources Report. IUCN, Gland, Switzerland. 456 pp.        
• 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; https://doi.org/10.3354/meps11591.  
• Dutra, E., Koch, M., Peach, K., Manfrino, C. (2015) Tropical crustose coralline algal individual and community responses to elevated    pCO₂       under high and low irradiance. ICES Journal of Marine Science; https://doi.org/10.1093/icesjms/fsv213.     
• Koch, M.S., C. Coronado, M.W. Miller, D.T. Rudnick, E. Stabenau, R.B. Halley, F.H. Sklar (2014) Climate Change Projected Effects on Coastal Foundation Communities of the Greater Everglades using a 2060 Scenario: Need for a New Management Paradigm. Journal of Environmental Management.  https://doi.org/10.1007/s00267-014-0375-y     
• Strazisar, T., Koch, M., Madden, C. Seagrass (       Ruppia maritima         L.) (2014) Life history transitions in response to salinity dynamics along the Everglades-Florida Bay ecotone Estuaries and Coasts https://doi.org/10.1007/s12237-014-9807-4.        
• Strazisar, T., Koch, M., Madden, C., Filina, J., Lara, Pedro, U. and Mattair, A. (2013) Salinity effects on    Ruppia maritima       L. seed germination and seedling survival at the Everglades-Florida Bay ecotone Journal of Experimental Marine Biology and Ecology 44: 5129–139.        
• Strazisar, T., Koch, M., Dutra, E., Madden, C.       (2013)  Ruppia maritima   L. seed bank viability at the Everglades-Florida Bay ecotone Aquatic Botany 111 26–34.    
• 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: Global Change Biology 19, 103–132, doi: 10.1111/j.1365-2486.2012.02791.x        
• Iz, B.H., Berry, L., and Koch M. (2012) Modeling regional sea level rise using local tide gauge data. Geodetic Science DOI: 10.2478/v10156-011-0039-2.        
• Holmer, M., Pedersen, O., Krause-Jensen, D. Olesen, B. Petersen, M.H., Schopmeyer, S., Koch, M., Lomstein, B., Jensen, H.S. (2009) Sulfide intrusion in the tropical seagrasses    Thalassia testudinum       and    Syringodium filiforme       . Estuarine and Coastal Shelf Science.       85: 319–326.    
• Jensen, H.J., Nielsen, O.I., Koch, M.S. (2009) Phosphorus release with carbonate dissolution coupled to sulfide oxidation in Florida Bay seagrass sediments.    Limnology and Oceanography.       54(5): 1753–1764.        
• Koch, M.S., Kletou, D.C., Tursi, R. (2009) Alkaline phosphatase activity of water column fractions and seagrass in a tropical carbonate estuary, Florida Bay.    Coastal Estuarine and Shelf Science       . 83: 403–413.        
• Rosch, K. and Koch, M.S. (2009) Seagrass (Thalassia testudinum) nutrient recycling along a trophic gradient in Florida Bay.    Bulletin of Marine Science       84(1): 1–24.        
• Nielsen, O. I., M.S. Koch, C.J. Madden (2007) Inorganic phosphorus uptake in a carbonate-dominated seagrass ecosystem.    Estuaries and Coasts       30(5):827-839.        
• Koch, M.S., Schopmeyer, S.A., Nielsen, O.I., Kyhn-Hansen, C., Madden, C.J (2007) Conceptual model of seagrass die-off in Florida Bay: Links to biogeochemical processes. 350:73-88.    Journal of Experimental Marine Biology and Ecology       .        
• Koch, M.S., Schopmeyer, S.A., Holmer, M. Madden, C.J., Kyhn-Hansen, C. (2007)    Thalassia testudinum       response to the interactive stressors hypersalinity, sulfide and hypoxia.    Aquatic Botany       87:104-110.        
• Koch, M.S., Schopmeyer, S.A., Kyhn-Hansen, C., Madden, C.J. (2007) Synergistic effects of high temperature and sulfide on tropical seagrass.    Journal of Experimental Marine Biology and Ecology    341:91-101.        
• Koch, M.S., Schopmeyer, S.A., Kyhn-Hansen, C., Madden, C.J., Peters, J.S. (2007) Tropical seagrass species tolerance to hypersalinity stress.    Aquatic Botany    86:14-24.        
• Nielsen, O. I., M.S. Koch, H.S. Jensen, C.J. Madden (2006)    Thalassia testudinum       phosphate uptake kinetics at low in situ concentrations using a    33       P radioisotope technique.     Limnology and Oceanography 51: 208-217       .
• Kieckbusch, D. and M.S. Koch (2004) Trophic linkages of primary producers and consumers in fringing mangroves of tropical lagoons.     Bulletin of Marine Science       74(2):271-285.        
• Gras, A. and M.S. Koch (2003) Phosphorus uptake kinetics in the tropical seagrass    Thalassia testudinum       .     Aquatic Botany    76:299-315.        
• Koch, M. S. and J. M. Erskine (2001) Sulfide as a phytotoxin to the tropical seagrass,    Thalassia testudinum       :  Interactions with high salinity and temperature.    Journal of Experimental Marine Biology and Ecology    266:81-95.        
• Koch, M. S., and C. Madden (2001) Patterns of primary production and nutrient availability in a fringing mangrove tropical lagoon in the Bahamas.    Marine Ecology Progress Series       219:109-119.        
• Koch, M. S., R. Benz, D. Rudnick (2001) Solid-phase phosphorus pools in highly organic carbonate sediments of northeastern Florida Bay.    Estuarine and Coastal Shelf Science       52:279-291.        
• Erskine, J. M. and M. S. Koch (2000) Sulfide effects on    Thalassia testudinum       carbon balance and adenylate energy charge.    Aquatic Botany       67:275-285.

Scholarly Activities

• Google Scholar
• Marine Lab