By: Eli Lusty

In abundant times, oysters were a staple – not a delicacy. It is said that in young New York city, before the flourishing oyster beds were reduced to 1% of natural levels, a million oysters were consumed per day.

The loss of oyster bed coverage is a positive feedback loop for pollution since they’re filter feeders that clean the water around them of both normal particles and pollution. So fewer oysters means more pollution. The absence of these scrumptious little bivalves is felt with the excess pollution present in the New York estuary today.

For oysters, a decline in their population spurs a vicious cycle As the concentration of pollutants like nitrogen and phosphorus grows, it chokes out and kills molluscs. 

So as the natural population of oysters have fallen, there has been an uptick in oyster farming to satisfy the shortfall in supply. But since this farming must take place in an already sensitive ocean environment, there has been resistance.

But first, the positives!

Oyster aquaculture is a solution, not a problem, and I’ve pinned down its four main benefits:

  1. They are a terrific source of protein and few people would be upset if they represented a larger portion of our regular diet.
  2. They scrub pollution from the waters they live in. (Albeit if the pollution is strong it renders them uneatable). Even the short 3-year lifespans of farmed oysters reduces pollution in surrounding waters, as I’ll cover more below.
  3. Oysters sequester carbon by transforming it into their calcium carbonate shells! Meaning they have a net negative carbon production.
  4. These are just some of the attributes that make oyster farming a sustainable economic activity. A sea farm remains well within the Doughnut Theory of Economics – which measures economic activity by the dual values of planetary and social boundaries -by providing a highly valued livelihood that doesn’t adversely impact the earth. 

However, a common objection to increasing oyster bed coverage in a farm is the loss of eelgrass coverage.

Eelgrass, an underwater flowering plant, is a crucial part of the ocean ecosystem. The roots lock silt into the seabed and improve water clarity, and their soft green leaves/blades create forests that are a haven for a multitude of creatures. Oyster beds frequently begin on the seafloor, while some methods use cages that rest on the bottom. Naturally, these beds and cages compete for space with the eelgrass. In recent years across North America we have seen some oyster cultivation projects discarded and operating farms dismantled in the name of eelgrass. Oysters however, are not the enemy of eelgrass, and modern ocean conditions march in lockstep with their healthy development like never before.

The real culprit is damage caused by agricultural runoff, as nitrogen and phosphorus washes off our farm land and into the ocean. An essential nutrient for the oceans yes, but we use it to supercharge the growth of plants on land. When it reaches the water it supercharges the growth of algae, the algal blooms grow so thick it cloys the water’s surface and blocks sunlight. When algal blooms die they create oxygen-deprived dead zones in the water that kills sea life below.

These dead zones caused by agricultural runoff have led many leading marine scientists to say “nutrients are the greatest contamination threat to coastal waters worldwide.” (Link)[

But nitrogen, the most crucial addition to our on-land agricultural system, is also an important factor in a young oyster’s growth! Oyster beds filter nitrogen from the water at a prodigious rate, and although they can cost a fair bit to establish, they are incredibly cost-effective to maintain. Ultimately, oyster beds can save tens of millions of dollars from being sunk into water treatment facilities (link).

New studies are coming out that show these nitrogen-storing little critters dramatically cut the incidence of wasting disease in nearby eelgrass populations.

Grounded oysters cultivated directly on the ocean floor, do reduce the space covered by eelgrass, but they will dramatically improve the health and quality of adjacent eelgrass and provide a home for sea life within the oyster reef itself. Oysters are known as ‘ecosystem engineers’, the rough shells of even a single oyster provide a habitat for other small creature, and as oyster beds grow to form reefs and large structure, they provide a habitat for increasingly more and larger animals.

But for the eelgrass question in particular, oyster cultivation does not need to take place on the ocean floor and can happen in floating cages that only partially block sunlight to the eelgrass below!

What can you do to improve the quality of our territorial waters? Increase oyster demand! Increase the demand for farmed oysters! Only one way to do that – eat more oysters (and have some wine while you’re at it).

If you haven’t slurped these delights before, I’ll happily buy the first plate for you.

Eli Lusty is an economics graduate and marketing consultant who volunteered for the Green Party in Halifax last election, who has found a way to continue contributing to conservationism through his writing, participation in the Ocean Bridge program, and voracious thrift shopping!

He recently launched a project, Carbon Labels Canada, dedicated to bringing carbon-footprint labels to food packaging. We deserve to know the footprint of our food and its packaging before we buy it.

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