Did you know that over 7 million tonnes of mollusc shells are thrown away into landfills or dumped back into the sea as unwanted waste every year?
Not only is this a waste of financial resources, it’s also incredibly harmful to our ecosystem and a waste of potentially useful material. Dr. James Morris and a team of CACHE researchers from the Royal Belgian Institute of Natural Sciences have recently surfaced this problem and are currently considering environmentally and economically sustainable options for the shells.
How can re-using these shells help our aquaculture?
Dr. Morris has proposed many exciting ideas for the use of these discarded shells that in the long run will help to restore damaged oyster reefs and, in turn, cultivate the growth of new oysters! In a quote from a recent article, Dr. Morris said, "Healthy shellfish populations can have many benefits to the environment: cleaning the water, providing a complex structure for other organisms to call home, and also acting as a coastal protection structure."
Here are a few of his proposals:
1. Mollusc shells make a great source of calcium for farmers
Mollusc shells are over 95% calcium carbonate—which is frequently used for agriculture. Farmers could spread crushed shells on their fields to control the acidity of their soil. Or, feed them to egg-laying hens as a calcium supplement!
2. Mollusc shells can replace the need for unsustainable limestone mining
Aside from agriculture, calcium carbonate is also often used in cement mix AND wastewater treatment! Currently, most of the calcium carbonate we use comes from unsustainable limestone mining. By using mollusc shells as a secondary source of calcium carbonate, we could reduce mining efforts while finding a productive use for this biomaterial.
Dr. Morris outlines how reusing these shells is “a perfect example of a circular economy.” The shells are undoubtedly valuable, and taking advantage of their value rather than throwing them away will help improve sustainability in the aquaculture industry. Additionally, it will help shellfish growers and processors economically.
While there is still research to be done on the topic, and proposals must be approved before we can start implementing new policies, this is a huge step in the right direction for sustainable aquaculture!
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