As a marine biologist working on animal-environment interactions,and focused on environmental changes driven by human activities that modify conditions for economic or societal benefit, I was surprised and intrigued to find out about bivalve gardening.
First things first:
What is bivalve gardening?
If you split the words you have your explanation. It refers to the gardening (= growing for personal use) of bivalve species, which are those marine animals with two (=bi) shell halves (=valves). Mussels, oysters, scallops, cockles..all form part of the big bivalve class.
How do you engage in bivalve gardening?
The start of the bivalve garden is somewhat similar to the terrestrial version. Yes, You could garden bivalves by obtaining seed (that’s how young individuals are called) and growing them until big enough for consumption. Seeds are the first ‘benthic’ (attached to the seabed) stage of young life stages of these species, which start their life floating in the water.. so you can put out collectors to attract the larvae to settle down and then you obtain your seed. Or other sources are from natural populations.
So, the start seems similar enough, But what are the differences between this aquatic and a terrestrial way of gardening? What are the risks and what are the challenges?
Bivalves are filter feeders, this means that they eat naturally available particles (mostly plankton) which inhabit the water column. While the availability is seasonally variable, bivalves can cope with this variability and thus their cultivation will not require any addition. Moreover, by providing this filtration bivalves can also act as the ‘sea cleaners ‘ and are often given lodes because of it. Free filters..
Because of their filtration, bivalves are also prone to be full of contaminants. Yes, because while on one hand this feeding strategy makes it optimal for circular economy strategies, and requires very little investment, on the other it makes it very difficult when it comes to food security. You don’t want to cultivate near a sewer for example, or near industry outlets. But nowadays, many coastal areas are polluted with some kind of contaminants or other, including micro plastic which is indeed found within bivalve tissues. So I would be careful..
Nonetheless, even if water quality assessments might be too expensive to be carried out, in some regions (like Denmark) guidelines on sanitation are provided. Although these are only a guide, and no restrictions are placed as long as nothing is sold...
Like traditional gardening, bivalve gardening can also be considered to be too small scale to have real impacts. However, there are still things to consider. For example, invasive species can be brought in more easily in the marine environment when moving seeds. Bivalves have a fast reproduction also, this means that genetic diversity in the natural nearby areas may be influenced. With plants, harvest is usually before new seeding occurs, while bivalves might already reach reproductive maturity and spawn, with greater chances of successful spreading. Moreover, the chance of leftovers amd spreading is greater, due to lower accessibility in the coastal environment and greater chance of environmental catastrophes hitting and damaging (ie storms).
And environmental benefits?
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