Marine researcher Loretta Roberson believes rethinking how we grow seaweed has the potential to clean up oceans, replace fossil fuels and protect coastlines from violent weather. She’s headed to Puerto Rico early this year to put her theories to the test.

By Rebecca Fanning
Medill Reports

On the southern coast of Puerto Rico, there’s a place where abandoned sugar plantations dot the shoreline, residents of illegal homes dump waste directly into the ocean and blooms of green algae rise to the surface, a visual reminder of the water pollution that’s present here. Known to many as one of the island’s largest estuaries, Jobos Bay is framed by two major power plants and several economically depressed towns. It’s also the site of the Jobos Bay National Estuarine Research Reserve, a federally protected area recognized for its seagrass beds, coral reefs and mangroves.

Marine scientist Loretta Roberson believes that Jobos Bay is the ideal place to test and implement a large-scale, mechanized seaweed farm to replace the land-based, inefficient seaweed farming currently used to produce fuel, chemical feedstock and animal feed. Eucheuma isiforme, the type of red seaweed she plans to grow, could become a sustainable and effective alternative for the agricultural industry and potentially an insurance policy against the shifts accompanying climate change. Growing seaweed in Puerto Rico’s warm waters make it a fertile testing ground as scientists predict oceans will warm in the coming years. It also has the potential to clean up polluted water and even create a storm surge buffer, helping protect a territory recently ravaged by Hurricane Maria.

“We don’t need to add extra nutrients, we’re not using up space on land, and we can actually be helping clean up the environment or restoring habitats. That is where I want to go with this,” says Roberson, who conducts her research from the Marine Biological Laboratory in Woods Hole, Mass.

Together with a team of researchers and corporate-backers, along with support from the U.S. Department of Energy, Roberson will design, test and implement open-ocean seaweed farms at scale. While seaweed farming has been around for centuries, especially in Asia, U.S. farming has lagged behind, in part because of the labor-intensive planting and harvesting processes, and limited understanding of the potential for the crop.

Before starting the research in earnest this January, Roberson took time to chat with Medill Reports about her four-year grant and how she’s optimistic this project could upend agriculture for the better.

Medill Reports: How did the seaweed project get started?
Loretta Roberson: At the University of Puerto Rico, we actually started a project to look at using seaweed for biofuels. And it was something that I really believed in strongly. At the time, and probably still currently, people and scientists had been focusing on microalgae to produce biofuels, but there was always this bottleneck of going to the large scale because they had to use ponds on land. They had to use up land that could be used better for food, say, for people. And it was really hard to harvest that; there were just lots and lots of issues.

The first step was really to show definitively, at least with modern techniques and mechanization, that we can grow a lot of seaweed for a competitive price with petroleum products. With the Asian farms, that’s pretty much all run on manual labor.

MR: How is your plan similar or different from the 3D seaweed farms currently popular in New England?
LR: It’s different and similar. I like to think of it as serving multiple purposes. Yeah, we can make a biofuel more sustainably than is currently done. We don’t need to take up valuable space or water or add extra nutrients to the sea. But in addition to that, the seaweeds actually can help clean up the environment and water quality, so that includes nitrogen waste from say a mussel farm or fish farm. So, if you can co-locate them it will be much more beneficial and more sustainable.

MR: How did you choose Puerto Rico?
LR: My rationale there is several-fold. One is this corporate partner is a red seaweed that produces carrageenan which is widely used [as a thickener in food production]. It has a ready market already. But also, just because the oceans are really warming and taking up most of the heat coming into the planet. So we’re going to have to focus more on species that can tolerate warm temperatures. In the tropics or subtropics, we can have continuous year-round harvests.

MR: How did you choose Jobos Bay?
LR: Number one, they’ve been constantly monitoring nutrients throughout the bay for a long time, like 13 years or so. So we have before and after, really good maps of the benthic habitat so we know we’re not going to be installing over seagrass or coral reefs. And then we know that there’s a history of a lot of excess nitrogen coming into the bay from the abandoned sugar plantations.

We’re hoping that we can really get a better handle on the capacity of these seaweed farms to take up those excess nutrients from the environment.

MR: So you guys are using Puerto Rico, but at some point, maybe the oceans off of the Carolinas will be considered tropical waters, too. Is that correct?
LR: Right, exactly. And right now, we can grow it throughout the Gulf of Mexico, up the Florida coast and all throughout the Caribbean as well as Hawaii. That’s quite a bit of area.

MR: How do you measure your impact? And what exactly are you measuring?
LR: We do it over time and at different locations along the farm system. Both in the seaweed and in the water. So you would expect if the seaweed is removing that nitrogen, then at the downstream end of the farm system, we should see a lower concentration of nitrogen than at the upstream end.

And one thing that we’re planning in our project is to really monitor how the other organisms are using it, so I think it can be positive in the sense that we could be creating new habitats that will allow things, especially fish that need some connectivity between habitats to survive.

MR: What is the biggest hurdle getting the pilot up and running?
LR: Permitting is actually really difficult and a really long process. So many different agencies are involved and you really have to prove to them that look, it’s not that much risk and we’ll get a lot of really good information from this pilot test. And we really have to be able to mechanize that seeding and harvesting in a way that’s cost effective.

For me, those two things are going to be the biggest. I think the seaweed is going to perform just fine.