Monitoring Macroalgae Using Acoustics and UUV
Marine macroalgae, also referred to as seaweeds or kelp, are a group of exceptionally diverse aquatic plants. Macroalgae can be found along nearly all coastlines around the globe and in some cases also in the open ocean. They have traditionally been used for food and feed, as well as fertilizer. In 2016, the world produced approximately 26 million wet metric tons of seaweed, primarily through highly labor-intensive farming techniques. While macroalgae production has increased six-fold over the past quarter-century, the current state of macroalgae “mariculture” is not capable of achieving the scale, efficiency and production costs necessary to support a seaweed-to-fuels industry. Dramatically increasing productivity will require significant advancements in the domestication of macroalgae and new farming technologies. To accelerate the development of critical tools and technologies, the MARINER program is supporting projects in five areas: 1) Integrated Cultivation & Harvest System Design, 2) Critical Enabling Components, 3) Computational Modeling, 4) Monitoring Tools, and 5) Breeding & Genomic Tools.
Project Innovation + Advantages:
The Woods Hole Oceanographic Institution will lead a MARINER Category 4 project to develop an autonomous unmanned underwater vehicle (UUV) system for monitoring large-scale seaweed farms for extended periods. Compared to more costly human labor and boat operations, UUV systems present an attractive option for consistent, daily monitoring of large-scale, offshore seaweed farms. The system will routinely survey and quantify key parameters such as infrastructure health, macroalgae growth rate, and nutrient content of the water. An upward/downward split-beam acoustic echosounder will use sonar technology to monitor the longline array used to grow the macroalgae, quantify growth on the longlines, and detect fish/zooplankton in the water column. Environmental sensors include a nitrate sensor (nutrients) and a package for collecting temperature and salinity data. A panoramic camera system will be used for close inspection of infrastructure and anomalies, with images available to operators within 24 hours of capture. Real-time processing of acoustic data, fed back into the autonomy system, will be used to map infrastructure and navigate the UUV relative to longlines for macroalgae sensing. Ultimately the UUV-based system will be able to operate in real conditions offshore and over large areas without human intervention.
If successful, MARINER projects strive to develop the tools needed to allow the United States to become a world leader in marine biomass production for multiple important applications, including the production of biofuels.
Production of biofuels from domestically produced marine biomass could lessen U.S. dependence on foreign oil, bolstering energy security.
Growing large amounts of macroalgae would not compete with land-based food crops, requires no fresh water and can be grown without the addition of energy-intensive, synthetic nitrogen fertilizer. Large-scale macroalgae cultivation may help reduce the negative effects of nutrient overload and ocean acidification in many coastal ocean regions.
A domestic macroalgae industry would not only create a valuable new source of domestic energy, but also create significant new economic and employment opportunities in many waterfront communities along the U.S. coasts from Maine to the Gulf of Mexico, Alaska, and the Pacific Islands.