||Macroalgae Farming: A Strategy for Economic Growth and Nutrient Mitigation
The estuarine system of the Chesapeake Bay has experienced a “tragedy of the commons”
through nutrient loading, degraded oxygen levels for marine life and a decrease in
system function for the Bay watersheds’ inhabitants. The US government has called
for the restoration of the Chesapeake Bay. This paper proposes an aquaculture practice
that may assist that goal, macroalgae (seaweed) farming, which can convert excess
nutrients to biomass for harvest and conversion to economic goods. While this practice
cannot fix our nutrient problem--nutrients should be stopped at their sources, like
farm fields, hardscape, power plants and automobile tailpipes--it can quantitatively
reduce nutrients in the waterway.
This paper examines macroalgae farming for the practice’s production capability per
square meter (tissue contains 3-5% Nitrogen, .01% Phosphorus, and 30% Carbon) in the
waterway and as a method to meet regulatory goals of the Environmental Protection
Agency (EPA). EPA calls for the “development of non-traditional Best Management Practices
like algal scrubbers.” Similarly, NOAA refers to Ecosystem-based Management as a
national priority and the “potential for aquaculture of shellfish and seaweed (algae)
to mitigate impacts of climate change (e.g., sequestering carbon, bioextraction).”
The farming process extracts nutrients through harvest and is sustainable by growing
a biomass in waterways rather than relying, like agriculture, on fresh water (irrigation
currently uses 60% of global fresh water which is not sustainable). Further, the practice
does not use arable land, which is increasingly under pressure from growing populations
and energy crops.
Macroalgae farming is an established 6 billion dollar industry worldwide. The biggest
use is human consumption followed by markets such as cosmetics, aquaculture feed,
agar and carrageenan, iodine, fertilizers and more. The global production of farmed
seaweed doubled between 2000 and 2012. This paper recommends several niche markets
that can make the enterprise profitable in the US. Nutrient trading also provides
a revenue stream with current prices for nitrogen removal at $8/lb to $20/lb. It compares
this price to other methods of nitrogen removal including Wastewater Treatment upgrades
and agricultural practices (cover crops, etc). Production costs of macroalgae biomass,
according to the literature and this author in the field, vary between $6.60/lb and
$42/lb for nitrogen removal. Nutrient trading can probably not cover the cost of the
practice, and therefore we must look to the private sector to monetize the biomass.
The government could decide to engage in a Public-Private Partnership to fund the
strategy initially until the private sector undertakes the business enterprise with
no further funding necessary.
The paper explores one scenario under which a Bay state, Virginia, may mitigate its
atmospheric nutrient load (1%, or 578,001 pounds of Nitrogen), for which there are
no Best Management Practices, by dedicating 3.8 square miles to the enterprise. The
practice would result in 107, 037, 222 lbs of wet biomass available for use by markets.
The government spends approximately $.5 billion/yr to restore the Chesapeake Bay with
only modest success. A dedication of 5%, or $25,000,000, would initiate the enterprise
and, within two to three years could possibly be self-sustaining, with an increase
in jobs and sustainable biomass for the economy. Such a project would provide a model
for Restoration of the Commons, or restorative commerce, and could be implemented
in eutrophic waterways around the globe.
1. Macroalgae farming provides a way to harvest nutrients in eutrophic waterways
2. Atmospheric deposition has no Best Management Practice for mitigation
3. Macroalgae farming can mitigate, as an example, 1% of Virginia’s TMDL (atmospheric)
through dedication of 3.8 sq mi of Chesapeake Bay
4. The harvested biomass can provide material for markets, like cosmetics, consumer
fertilizer, and specialty papers.
5. Macroalgae farming cannot “fix” the nutrient problem of eutrophic waterways (too
much marine space would be required), but it can positively impact the problem
6. Macroalgae outcompete microalgae, the cause of dead zones, and farming operations
should be located close to nutrient hotspots, but beyond Submerged Aquatic Vegetation
(which provides oxygen)
7. Biomass harvest must be timed to take advantage of oxygen production and avoid
8. A macroalgae farm can potentially lead to a profitable business venture and a
productive public-private partnership.