A blade of seagrass is a powerful thing

Even though seagrasses occupy less than 0.2% of the world’s oceans, they account for more than 10% of all carbon trapped in the sea. In a world and time where we are producing more carbon than we should be and can manage, making sure that seagrasses are healthy and abundant is extremely pertinent. Winni Wang is one such seagrass scientist working to understand the biology of seagrasses and what threatens them.

Winni is a 5th year PhD candidate in the Department of Microbiology working with Dr. Ryan Mueller. Winni specializes in studying the microbiome of different plants, which for her PhD happens to be seagrasses. The microbiome is the community of microorganisms in a particular environment, and therefore it is found on all living things. By studying the microbiome on different seagrasses, Winni hopes to determine how anthropogenic (human-induced) stressors affect seagrass plants as a whole through changes in the microbiome.

If you’re like me and you love marine megafauna, then when thinking about seagrass beds you most likely are picturing a big manatee slowly grazing on seagrass in tropical, warm waters. Well, then you might be surprised to know that seagrasses don’t only occur in warm, tropical waters. In fact, there are over 60 species of seagrass worldwide and they occur in all kinds of habitats and climates. As a matter of fact, there is a species of seagrass right off of our coast here in Oregon, in Yaquina Bay, which is one of Winni’s study sites for her thesis research.

Eelgrass at Yaquina Bay.

Winni with the experimental tanks at HMSC.

Her work in Yaquina Bay relates to understanding how seagrasses are affected by eutrophication. Eutrophication occurs when an excessive amount of nutrients enters an aquatic environment, often due to land run-off, which in extreme cases can lead to severe oxygen depletion in those habitats resulting in death of plant and animal life. Winni hypothesized that with increased nutrients in a seagrass habitat, the microbiome of the seagrass would change in a way that would have an effect on the overall plant. In order to test this hypothesis, Winni had to carry out controlled lab experiments but not without collecting her test species first. She collected over 200 seagrass individuals as well as buckets of mud from Yaquina Bay, which she took back to Hatfield Marine Science Center where she set up tanks for her experiment. The tanks housed seagrasses and the collected mud. Half of the tanks included added fertilizer to test the effects of nutrient addition, and the other half were left as controls. Over the course of the experiment, Winni tracked plant growth metrics and nitrogen concentrations of the tanks, as well as collecting root and leaf samples to look at the microbiomes on both of those parts of the seagrass.

The mud buckets.

Winni found that the fertilizer affected the roots in such a way that it changed the microbiome community found there. This change resulted in enrichment for microbes that could cycle sulfur, which could potentially have quite detrimental effects on seagrasses. This is because seagrasses grow in anoxic, or oxygen-low, environments where sulfur is found in its reduced form, hydrogen sulfide. Usually, in environments without excessive nutrient input, seagrasses are able to deal with sulfide, which is typically toxic to plants and animals. However, with increased nutrients, the seagrasses may become overwhelmed by the amount of sulfur in the water as it gets converted into hydrogen sulfide. At certain thresholds, the sulfide ends up becoming toxic to seagrasses. Thus, Winni’s research shows that excessive fertilization to seagrass environments, potentially from land run-off, could have detrimental impacts on seagrasses.

Another chapter of her PhD takes Winni half way across the world to the Mediterranean. Well, it is not so much that it takes Winni to the Mediterranean, it is more that the Mediterranean comes to her! Through her advisor, Winni was able to obtain seagrass samples from the Mediterranean. What makes these samples unique is that they were taken from a site near a naturally occurring underwater volcano. You may be wondering how this is relevant to Winni’s research since she is trying to figure out how human-induced stressors impact seagrasses. Well, the underwater volcano spews carbon dioxide into the water, which makes the water more acidic. This phenomenon is essentially a natural experiment because it mimics the effects of human-induced ocean acidification, which is becoming a problem around the world’s oceans. The results are still underway but they will help fill some of the knowledge gaps concerning the effects of ocean acidification on organisms.

This blog started by emphasizing how important seagrasses are in sequestering carbon, however it is not the only thing that makes these small, unassuming plants so vital to our lives and the lives of many other organisms. Coastal waters with seagrass beds have been found to contain relatively less human pathogens than areas without seagrasses. This is because seagrasses filter the water and are able to remove a lot of pathogens. Furthermore, they are important in preventing coastal erosion and often make coastlines more resilient to storms. Not only are they also important habitats to some beloved marine megafauna (manatees, sharks, turtles) but they are also important for many smaller, but equally ecologically and economically important, species. For example, in Oregon, seagrass beds may actually be helping mitigate ocean acidification which is having a negative impact on oysters as it affects the strength of their shells.

Winni’s life, both at Oregon State and before her arrival here, has not been all about seagrass science though. To hear more about her background and some of the struggles and lessons that she has had during her tenure here, tune in on Sunday, March 8 at 7 PM on KBVR Corvallis 88.7 FM or stream live. To follow Winni and her research, be sure to follow her on Twitter @ramenmicrobiome. Something that we weren’t able to cover on the blog but covered on the show, is that Winni is one of the founders of the Women of Color Caucus (WoCC) at OSU. Read about the origin story of WoCC here, follow their Instagram and Twitter pages and join their listserv here.