Carbon Isotope Fractionation By Halophila Stipulaceae
Seagrass effects on CO2 burial
Vegetate Coastal environments are considered an efficient area for organic carbon burial and are often referred to as the blue carbon system. Those ecosystems include mangroves, salt marsh, and seagrass. Seagrasses are the only marine angiosperms (flowering plants) that evolved from land plants back to the sea around 70 to 100 million years ago during the Cretaceous, a period known to have hot temperatures and a high atmospheric CO2 level. They can be found globally on temperate and tropical coastlines of the world. As a blue carbon ecosystem, seagrasses are highly efficient carbon sinks and about 10% of the carbon buried in the ocean is attributed to this system. Most of the seagrass biomass is in the seabed giving the seagrass an advantage in terms of carbon storage, the seagrass stock most of the organic carbon in the sediment and not in living biomass. Unlike terrestrial plants' photosynthesis, the mechanism in seagrass is not entirely clear. Seagrass show a wide distribution of δ13C values compared to other angiosperms. This high variability in δ13C implies a dynamic photosynthesis mechanism. In fact, among other marine primary producers, seagrass has the most enriched δ13C values. This geochemical-based research will focus on Halophila Stipulacea (δ13C ≈ -8‰) the common species in the Gulf of Eilat. Our work combines diving sampling, stable carbon isotope analysis, and laboratory experiments. Understanding the factors affecting the isotopic value will provide information on the carbon fixation in Halophila Stipulacea. Thanks to its original starting point, seagrass has a great potential to benefit from the recent rise in atmospheric CO2 level and supply new information on the global carbon cycle.
