My research interests include wetland biogeochemistry, global carbon and nutrient cycling, and impacts of climate change on these cycles.
Despite what you might hear in the media, human-caused climate change is a fact. A whopping 97% of scientists agree that the evidence for climate change is solid, and the other 3% probably didn’t understand the survey question. As the earth gets warmer, ice in the polar regions is melting at faster rates, which in turn causes the oceans to rise faster. As sea levels rise, habitats along the coast, such as marshes, will feel the effects of this ocean water, which is much saltier than the marshes are used to. This is concerning because coastal habitats provide numerous benefits and services. They provide habitat for commercially important fisheries and other marine animals, provide the first line of defense in the face of coastal storms by buffering waves and preventing shoreline erosion, and they store more carbon in their soils than any other ecosystem in the world. These ecosystems are able to suck up large amounts of carbon dioxide (CO2) from the atmosphere through photosynthesis. Plants then use this CO2 to make leaves and roots. The roots, made mostly of carbon, stay in the soil for a very long time. That’s because these ecosystems are near the coast, so they tend to stay wet, which slows down decomposition of the soils. But when sea level rise causes these ecosystems to become saltier, everything gets thrown out of balance. Plants get stressed and die, and the carbon, stored in the soils for thousands of years, is in danger of being released back to the atmosphere. My research focuses on what happens to this carbon once saltwater beings to intrude into coastal marshes.
So how do you test the responses coastal marshes will have to greater salinity? You go add a bunch of saltwater and see what happens! My research is currently being done in the Florida Everglades, the largest wetland in the U.S. Every month, we go out to the marsh and add salty water to the marsh, which effectively simulates the predicted salinity levels of these marshes 25 years from now. I then track CO2 levels to see if photosynthesis slows down with greater salinity.
So, what did I find and what does it all mean? Well, with higher salinity, photosynthesis did slow down, which means the plants took up less CO2 and, therefore, put less carbon into the soil. With less carbon in the soil, I saw that the soil started to break apart and collapse. This is very concerning because if the soils collapse, the whole ecosystem, as it currently is, disappears. This means that all the benefits and services the marsh provides to humans also disappears. However, there is hope. Proper coastal management and policy may be the key to helping these coastal marshes survive. Managing increased water inputs into these systems can push back the saltwater and allow these systems to survive for a little bit longer. Hopefully, this allows more salt-tolerant plants to colonize the marsh and stabilize the soil.
2. Carbon dioxide, methane, and sediment biogeochemistry from Alabama’s coastal marshes
Alabama has a diverse array of coastal marshes despite its relatively low amount of coastline. However, these wetlands have been lost at astonishingly high rates over the past centuries as a result of water channel manipulation, anthropogenic encroachment, and natural subsidence. Now, given current and future climate change, these marshes face many more stressors in the near future. Coastal marshes survive by storing carbon and building elevation, but this function is modified by saltwater intrusion. I am interested in the health of the coastal marshes of Alabama, in particular when it comes to their current ability to store carbon. I found that the ability of these marshes to store carbon continue building elevation may already be in danger.