Staying Afloat Under Water
Ray Grizzle motors out to a quiet cove in Little Bay where the University of New Hampshire (UNH) buoys bob in the calm water. Clad in neoprene waders, he jumps out of the boat into waist high water and walks gingerly so as not to stir up too much sediment around the cages that hold thousands of American oysters. These native oysters, raised in flat mesh bags that stack up in the cages like drawers in a dresser, are the kind people like to shuck, slurp, and savor at three dollars a piece in fine restaurants around the world.
Grizzle, a professor of biology in the College of Life Sciences and Agriculture (COLSA) at UNH, is analyzing the interplay between the oysters and a spaghetti-like seaweed, native to these waters, known as Gracilaria. As with other seaweeds, Gracilaria has the ability to uptake the waste products of sea creatures – in readily available forms of nitrogen such as ammonia, as well as phosphate and carbon dioxide – for its own growth. “I like to emphasize that we’re trying to tie together food production with environmental improvements,” says Grizzle. “We’re looking at ecosystem services with water filtration and the removal of nutrients, which will be good for other creatures in the estuary as well as the management of pollution sources on land.”
This research is being conducted alongside the work of four other scientists at UNH who are all are breaking ground – or, rather, water – in a new take on integrated multi-trophic aquaculture in the Northeast. Drawing upon their individual foci, Ray Grizzle, Chuck Walker, Larry Harris, Chris Neefus, and David Berlinsky are combining decades of New Hampshire Agricultural Experiment Station (NHAES)-funded research to strengthen the local economy with sea ranching techniques that can be applied to aquaculture endeavors in other areas as well. “Collaborating is much more fun than working alone, because you have the exchange of ideas and the potential for new innovations,” says Harris of the comprehensive project that seeks to grow oysters, urchins, bait worms, and finfish along with seaweeds in lease sites across the region.
Each animal produces a high nutrient effluent that, when concentrated in traditional aquaculture, can over-enrich coastal waters. Seaweed is both a mitigating factor that extracts those nutrients for its own growth, and a nourishing part of the organisms’ diets. Professor of biology Chris Neefus is studying the growth of seaweeds under varied conditions in the controllable environment of six chambers, purchased with NHAES funds, which regulate temperature and light. Resembling oversized bar refrigerators, they’re stacked up in a row in the Neefus Laboratory where Ph.D. student Lindsay Green monitors the development of the conchecelis – or filament – growth stage in every increment through to the mature blades of brown and red algae.
Seaweed aquaculture is a rapidly growing enterprise in the US with a $7.2B global market. That’s $35M in the US alone for a vegetable that’s happy to do the dirty work of taking both effluent and inorganic nutrients out of the water. Furthermore, seaweeds are high in alginic acid, which binds with heavy metals in the intestines rendering them indigestible, and, therefore, help with the elimination of toxins.
Most Americans recognize seaweed as a food product in the thin sheets of Nori used to wrap sushi or the finely sliced strands found in a sweetened seaweed salad, but a component of seaweeds – prized for its gelling quality derived from a high production of cell wall polysaccharides – is also used as an additive to edible and inedible products such as chocolate milk, ice cream, and toothpaste. Additionally, using thousands of tons, seaweed can be used as a base ingredient in biofuels.
Neefus used NHAES Hatch funds to conduct his initial research and deepen his understanding of cultivating seaweeds, which lead to a National Oceanic and Atmospheric Administration (NOAA) National Collaborative Sea Grant that was also distributed among his colleagues at the University of Maine, the University of Connecticut, and the Woods Hole Oceanography Institution. Neefus learned first-hand how the Japanese propagate sea vegetables by inoculating dead oyster shells with neutral spores and placing them in recirculating tanks for growth to the blade stage. Giant reels of rope slowly rotate in the water above the growing seaweed that attaches to the rope before it’s transferred to the ocean for the sun and sea to take care of the rest. For such varieties that reproduce blade-to-blade, the plants reach maturity and are ready for harvest in a couple of months.
Neefus’ research attracted the attention of Ocean Approved, LLC, a start-up seaweed company owned by Paul Dobbins and Tollef Olsen who now cultivate kelp on a rope stretched for three nautical miles six feet beneath the Portland harbor. Olsen, a former chef and food educator with an interest in the production side of the business, developed an innovative way to serve kelp, sliced into slender strips as an elegant and nutritious side dish. Currently a $3M company, Ocean Approved sells prepackaged kelp noodles in every Whole Foods market east of the Mississippi. Seaweed aquaculture is an emerging market with plenty of room for growth, and adding complementary organisms to its development is a boon to a rancher’s bottom line.
A single lobe of the gonad scooped from the shell of a living green sea urchin of commercial size fits perfectly in the hollow of a teaspoon. Known as uni, bite-sized urchin is on the menu in the best sushi restaurants in the US, and throughout Japan . . . but it is only available seasonally. Between December and March, the gonads are full of nutritive somatic cells that give uni its fresh, salty-sweet flavor, favorable rich gold color, creamy consistency, and finely crenelated surface. After that, gametogenesis in the reproductive cycle creates a degenerative process whereby nutrients are consumed by the germ cell and the flavor of the flesh becomes too bitter for consumption.
“Uni tastes like a wet saltine cracker,” says Chuck Walker, who’s been studying urchin reproduction throughout his career as a professor of biology in COLSA. When it comes to urchins in aquaculture, the industry’s approach is provincial, but Walker is the top gun ready to push those boundaries. Certain factors in the sea ranching of urchins are impossible to control: shorter day length beginning in September is the shift in photoperiod that initiates gametogenesis, and global warming has caused a rise in ocean temperature, which provides a less desirable habitat for the organism. Walker wants to effect change in the sea urchin itself, rather than the environment, and render the animal sterile. “I’m really interested in gametogenesis, and I know how to manipulate it in urchins,” he says about his method for controlling the number of chromosomes in their genes in order to create a new species of triploid urchins that cannot reproduce, and, therefore, will not have gonads that are metabolized through a biological cycle. Furthermore, truly non-reproductive urchins pose no threat to existing wild populations.
For an industry that once grossed $46M in the state of Maine during a time when urchins were harvested wild, the financial prospect of farming sterile urchins year-round would be enormous. COLSA’s Chair of the Biological Sciences Department, Larry Harris, had been breeding reproductive – or diploid – urchins in the hatchery at the UNH Coastal Marine Laboratory in Newcastle for ten years. There, he oversees students and research assistants who populate and maintain the eight 300-liter water capacity cylinders to raise baby urchins. During the winter spawning period, upwards of 300,000 pinhead-sized urchins are produced in each vat during each spawning cycle. The juvenile urchins are then transferred to grow out cylinders at the Coastal Marine Lab. Scavenging on naturally growing algae that clings to the spiraling walls of the cylinders, they grow large enough to be transported to a lease site in Little Harbor. “If you put a whole bunch of urchins of the same size together, pretty soon some are jackrabbits growing fast and others are inhibited. If you take away the jackrabbits, another whole crop grows up,” says Harris, who will conserve some larger urchins in the cage as brood stock. “When you drive over the first bridge on the way from Portsmouth to New Castle, you are crossing over a sea urchin lease site.”
The lease site has a shallow flat bottom covered in gravel and dead shells and has good tidal currents, which promote the growth of seaweeds to feed the urchins. Wire mesh cages are set on the bottom to protect the urchins from predatory fish and crabs for their initial growth period. After a few months, the urchins are released on the bottom to grow to commercial size. A single urchin can grow to be as big as a grapefruit and develop millions of eggs. With 21 days from spawning to settling tiny urchins, the hatchery is capable of raising up to 2 ½ million urchins each month.
Currently, the urchins Harris grows are used for research and demonstration, not for the market, but – combined with urchins of the eternal gonad - the possibilities for a commercial enterprise are astounding. Throw in some complementary fauna and flora, and you’ve got a recipe for perpetual success. Urchins are happy to clean the surface of oyster shells, and together with seaweed they work to nurture one another as well as clean up the bay. Bait worms, at a dollar a piece, grow quickly to be as thick as a finger and up to a foot in length. “Those are interesting animals. Rather aggressive,” says Harris. “If you have too many together, a whole bunch of them are missing their back ends.”
Eventually, the team will introduce finfish into the equation after securing permits for managing vertebrates in an open system. Professor of biology David Berlinsky is in the early stages of research, calculating how much ammonia is produced by specific fishes and extracted by seaweeds. Compliant with the guidelines of the Institutional Animal Care and Use Committee (IACUC), Berlinsky is currently monitoring black sea bass, summer flounder, and smelt in UNH’s Ritzman Laboratory. These fish thrive in a recirculating aquaculture system that requires a significant amount of energy to power the pumps and filters that are in constant use, offset by a small footprint with no nitrogenous waste that goes into the environment.
Local Oceans in Hudson, NY, a zero-waste commercial land-based aquaculture venture that grows sea bream, sea bass, and yellowtail, is interested in the results of Berlinsky’s studies in order to incorporate phyto-bio filters into their expanding operations. Berlinsky works closely with Neefus who recently received a small business innovation grant to generate such bio-filters with either seaweeds or other plants. “Recirculating systems are expensive to build and operate, so raising food fish is challenging,” says Berlinsky. “We import over 80% of our seafood, and it comes from places that don’t always grow it in a way we’d prefer they do. We have a dire need to raise seafood here, and we want to do it sustainably.”
Land-based systems can grow fish for millions of people, but they don’t do the important work of remediating pollution in our waterways. In an open system, the waste products produced by finfish can be removed by nearby seaweeds and the filtering actions of oysters and mussels. This co-culturing with oysters and seaweeds is a novel approach that is gaining the considerable interest of producers as well as coastal managers seeking phyto-remediation for high nitrogen levels in the water bodies they oversee. With benefits to the food chain, environment, and the economy, integrated multi-trophic aquaculture in an open system is certainly an attractive prospect. “If you have problems with one species, or if the price drops, you still have the other species to ensure that you’ll have an income,” says Harris. “There are advantages to diversity in this just as there are in other ecological systems.” Integrated multi-trophic aquaculture is a sustainable method for growing food from our coastal waters while improving the health of the environment.