Study shows some aquatic plants depend on the landscape for photosynthesis
ASU researchers have found that freshwater aquatic plants are not only affected by climate, but are also shaped by the surrounding landscape. In an environment where CO2 is limited, aquatic plants use strategies to extract carbon from bicarbonate. Scientists have identified trends in ecoregions around the world and have found a direct link between the availability of capture baking soda and the ability of aquatic plants to extract carbon from it.
All plants need carbon dioxide, or CO2, to live. They extract it from the air and use it during the photosynthesis process to feed themselves.
But what happens to aquatic plants? How do they get carbon dioxide?
Some have partial terrestrial forms, such as floating leaves or growth above water, which allows them to use carbon dioxide from the atmosphere. But for plants that live completely submerged in water, CO2 is limited and many of these plants have developed a mechanism to tap into other carbon sources. In this case, they extract it from bicarbonate, a natural mineral that comes from weathering of soils and rocks and affects plants.
In an article published today in Science, researchers at Arizona State University School of Life Sciences discovered that not only are freshwater aquatic plants affected by climate, but they are also shaped by the surrounding landscape.
"In this study, we are able to demonstrate that yes, in an environment where carbon dioxide is limited, plants use strategies to extract carbon from bicarbonate," said Lars Iversen, lead investigator of the study and researcher at the School of Life Sciences. "We see it in local rivers and lakes, but we also see it all over the world. We have identified trends in ecoregions and there is a direct link between the availability of capture bicarbonate and the ability of aquatic plants to extract carbon from it."
The study, which focused specifically on aquatic plants that live completely submerged, also showed that when plants have easier access to carbon dioxide, they use it as a carbon source, even if bicarbonate is available.
"One of the main points of this study is that aquatic plants are different. We cannot use our vast knowledge of terrestrial plants in the same way as aquatic plants," said Dr. Iversen, a researcher at Assistant Professor Ben Blonder's Ecology Laboratory. "This is very important because on a global scale, at least one third of the human population is very closely linked to freshwater systems. Deltas, drinking water and fishing grounds are therefore essential to human survival. If we want to understand how these systems will persist and change over the next 100 years, we really need to know how some of the main components and structures of freshwater systems work.
Environmental changes caused by human activity, such as deforestation, land cultivation and fertilizer use, are causing a significant increase in bicarbonate concentrations in many freshwater bodies around the world. Mr. Iversen said the results of this study will help researchers assess how ecosystem functions change if bicarbonate concentrations increase.
