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From Land to Sea

Matthew Oreska and Abby Lunstrum (a former VASG graduate research fellow at UVA) collect seagrass bed samples that they will use to measure carbon sequestration. ©A. Bartenfelder

Terrestrial restoration techniques for coastal environments

By UVA Ambassador Hung Truong

Aiming to address climate change through the coastal restoration of key plant species such as seagrass, mangroves, and salt marshes, Virginia Sea Grant Graduate Research Fellow Matthew Oreska is exploring techniques used in terrestrial rainforest restoration to preserve and restore large swaths of seagrass meadows along the Eastern Shore of Virginia.

Matthew Oreska in South Bay during summer 2016. ©A. Berger

Matthew Oreska steers a boat to a seagrass bed in South Bay. ©A. Berger

“Imagine reversing the effects of deforestation and slowing down climate change by paying somebody to leave a forest intact. Now imagine the same application being used to preserve and protect seagrasses and salt marshes within a coastal marine setting,” Oreska explains.

Deforestation, a practice that is witnessed most frequently in developing countries as a large income-generator for many people, is a large cause of ecological degradation and biodiversity decline.

“It was realized by governments and scientists alike that deforestation is a biodiversity problem, an ecology problem, a socioeconomic problem, and a climate problem,” Oreska adds.

The impact of removing one tree of significant size can be immense. Not only does it terminate the carbon sequestration services—the uptake of carbon dioxide by trees, but it also leads to additional release of carbon dioxide due to decomposition. In order to mitigate these ecologically harmful activities, governments have adopted policies based on the idea of incentivizing these loggers, through monetary means, to cease deforesting crucial habitats. The carbon credit system that has been developed for these types of incentive programs takes into account how many units of carbon dioxide are removed from the atmosphere by various terrestrial and marine organisms.

Into the Carbon Credit World

“The methodology seeks to address the effects of climate change while partially sustaining seagrass restoration through carbon offset credits,” Oreska says.

His work in attempting to quantify the amount of carbon sequestration by seagrass meadows contributes beneficially to this greater organizational effort—improving the pricing system for allocating carbon credits to similar “blue carbon,” the label given to carbon dioxide that is stored by coastal ecosystems. Each carbon offset credit represents a metric ton of carbon dioxide that is removed from the atmosphere. Labeled as a carbon credit equivalent, this measure can be equated to amounts of methane as well as nitrous oxide.

The research has yielded many additional benefits of seagrass meadows. Seagrass sediment beds are able to store plenty of carbon dioxide. Due to their anoxic properties, these sediments are able to prevent the decomposition of organic compounds that are transported by passing currents and trapped by the seagrass canopy. Less decomposition means less carbon dioxide being released into the system. Another added benefit to seagrass meadows comes in the fact that they require minimal management compared to their terrestrial vegetative counterparts which are subjected to periodic forest fires.  Outside of carbon sequestration, the potential role for seagrass meadows to temper waves, reduce turbidity, and stabilize shorelines holds immense benefits for developed coastal areas.

Not All Green is Good

With all of its strengths, seagrass meadows do exhibit weaknesses. Like other marine plant-life, they require a growth period of five to 10 years before being able to yield any carbon appropriation benefits. During this time, they are extremely sensitive to non-point source pollution—originating from multiple, unidentifiable sources, produced by the products of development and agricultural runoff. They are also vulnerable to a number of diseases such as Slime Wasting

Disease and hurricanes. Consequentially, the uprooting of a seagrass meadow would release concentrated amounts of carbon dioxide that have accumulated in the canopy and sediment beds of the system.  These setbacks are, however, negligible when stacked up against the potential benefits.

There is the additional concern that methane and nitrous oxide are being produced as a byproduct within seagrass meadows. Since methane is a more potent greenhouse gas than carbon dioxide, its presence in certain concentrations could negate the carbon uptake and storage benefits of seagrass and salt marshes. Further study is needed to quantify methane production caused by microbial activity in sediments.

Somewhere Beyond the Seagrass Seed

Oreska also looks to replicating the methodology for seagrass meadows, planting on a much larger scale to further study the carbon uptake effects of these marine plants. The idea would be to have a project on a large enough scale, that the receipt of these carbon offsets from seagrass carbon sequestration would be enough to finance the seagrass restoration. At the current price per metric ton, such a project would not be feasible within small systems. However, he hopes that municipalities across the U.S. will adopt the methodology, incorporating blue carbon plantings, and obtaining carbon credits to help reduce the cost of the project. For the time being, the recreational, ecological, and scientific benefits that these seagrass meadows provide will have to suffice. For Oreska, it’s all about being out in the field, and contributing to the advancement of scientific knowledge, one seagrass seed at a time.

About Matthew Oreska

Environmental conservation is nothing new to Matthew Oreska. It has been the overarching theme of his academic and research endeavors since his undergraduate years studying geology and economics at William & Mary. After earning his Masters in Biology at the University of Cambridge, Matthew narrowed his focus to aquatic ecology. He is now pursuing a PhD in Ecology at the University of Virginia, after working for a year for the Natural History Museum in Washington D.C. His research primarily focuses on landscape scale processes for ecological restoration of blue carbon—the label given to carbon dioxide stored by coastal ecosystems—marine plant types along the Eastern Shore. The topic of this article pertains to his project working with seagrass restoration on the Eastern Shore of Virginia. The result of the study is published in a paper titled Methodology for Tidal Wetlands and Seagrass Restoration which Oreska co-authored.