While forests are celebrated as carbon sinks, the ocean's capacity to sequester atmospheric carbon dioxide—known as 'blue carbon'—is immense. Traditionally, blue carbon focus has been on coastal wetlands and seagrass beds. The Maryland Institute of Chesapeake Bioculture is pioneering research into a third, highly scalable pathway: the cultivation of fast-growing seaweed, or macroalgae. The Chesapeake's nutrient-rich waters, while problematic for many reasons, provide an ideal growth medium for certain native and non-invasive seaweed species, turning an environmental challenge into a climate solution opportunity.
Our research begins with identifying the most promising species for carbon sequestration. We are evaluating native varieties like Gracilaria tikvahiae (red seaweed) and Ulva lactuca (sea lettuce), as well as assessing the ecological safety and efficacy of non-native but highly productive species like Saccharina latissima (sugar kelp) in Bay conditions. Our trials focus on growth rates, biomass yield per unit area, and the carbon content of the tissue. We are engineering novel cultivation rigs—low-profile longlines and floating grid systems—that maximize sunlight exposure and water flow while surviving the Bay's dynamic conditions, from storms to ice cover.
The carbon cycle in seaweed cultivation is complex. Through photosynthesis, seaweed absorbs dissolved CO2 from the water, which in turn causes the water to draw down CO2 from the atmosphere. The key to sequestration is the fate of the biomass. If harvested and used for food, bioplastics, or animal feed, the carbon may re-enter the atmosphere on a short timeline. Our research is specifically targeting long-term storage pathways. One major avenue is the intentional sinking of harvested seaweed into the deep, anoxic channels of the Bay, where decomposition is slow and carbon can be locked away for centuries. We are modeling the ecological impacts and carbon stability of this approach.
MICB's most innovative work involves integrating seaweed cultivation with other bioculture components to create synergistic carbon drawdown systems. In our 'Carbon-Farming Polyculture' model, seaweed lines are deployed above or adjacent to shellfish beds. The shellfish respire and release CO2, which is immediately captured by the seaweed. Simultaneously, the shellfish filter particles, increasing light penetration and boosting seaweed growth. Furthermore, the physical structure of the seaweed farm dampens wave energy, reducing shoreline erosion and protecting other blue carbon habitats like marshes. We are quantifying the total system carbon budget of these integrated farms.
The value of seaweed cultivation extends far beyond carbon. It is a powerful tool for eutrophication mitigation, directly removing excess nitrogen and phosphorus from the water column. It provides habitat for juvenile fish and invertebrates. Our economic research team is developing viable business models to make seaweed carbon farming attractive. This includes valuing the nutrient removal credits, developing premium markets for Chesapeake-grown seaweed products (e.g., organic fertilizers, cosmetics, biofuels), and creating protocols for the sale of verified blue carbon offsets. By proving that seaweed cultivation can be both an ecological powerhouse and an economic asset, we aim to catalyze its widespread adoption as a core strategy for a climate-resilient Chesapeake Bay.