• Angus Bishop


Updated: May 19, 2020

Have you ever been walking down the vegetable aisle of your local supermarket, looked at a carrot and thought “those kill fish”? I’m guessing the answer is probably no. If its yes then you’re probably a marine biologist or you’re wearing a tinfoil hat… maybe both. If it’s the latter, we have your address, and the ant-men are coming.

So what’s the connection? First off, it’s not just carrots, it’s all crops which are sprayed with fertiliser that are responsible for the mass genocide of millions of innocent baby fish or “ichthyoplankton”. The fertiliser can be washed off the fields and into the sea where instead of fertilising vegetables, it fertilises algae.

In the absence of any limiting factors, algae can reproduce exponentially. Patches of the ocean the size of the United Kingdom turn green overnight (or in some cases yellow and red). Side note: Often the algae which comprise these blooms release toxins either as a self-defence mechanism or when they die. These compounds can be deadly to all manner of marine life and in some cases, caused harm to humans.

The rapid proliferation in algal biomass is self-limiting; usually, iron or light become limiting factors and result in sudden mass mortality of algae in the bloom. Bacteria and fungi are then fed to gorge on the dead remains of the algae. However, the microbes are also self-limiting. As the plant matter is metabolised the quickly reduce the local oxygen levels are reduced to near zero resulting in a hypoxic zone.

Fish have a low tolerance to hypoxia. The fall in oxygen levels can stun, slow or even kill them, ichthyoplankton are particularly susceptible.

This is where the Jellyfish come in. Some jellyfish, like the moon jellyfish, aren’t really bothered by low oxygen levels (possibly a throwback from their ancestry in the pre-Cambrian period of low oxygen). They can continue normal functioning for hours in low oxygen. As ichthyoplankton are their natural prey, they are provided with easy pickings. The more they eat, the more baby jellyfish there are, the more energy they have for reproduction. So, there you have it, a flash tour to how your night vision giving vegetable might be devastating fish stocks. I’m not trying to be a sensationalist and create a war between pescatarians and vegans or even mass protests against broccoli. The aim of this article is to raise awareness of how much effect our daily lives has on the ocean. Squid ink ltd is devoted to showing you how you can use information such as this to become more environmentally friendly and make money in the process. Thanks for reading! All the information here is traceable back to peer-reviewed journals. If you have any questions, send us an email, or you can follow the links below to the articles themselves. We’re always open to comments or feedback so we can improve our content so get in touch and let us know what you think.

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