How Fish Poo is Pulling Its Weight in the Battle Against Climate Change
Fish poop produce nutrients for the survival of other marine organisms
Photo by: Franco Banfi/Biophoto/Alamy
We know how poop fertilizes our soil. What we excrete, the soil microorganisms welcome it as food. This same thing happens underwater; a lot of marine organisms rely on the constant fish poop to get nutrients for their survival.
But it’s more than just sustenance. It’s also a way how the ocean absorbs atmospheric carbon.
Marine ecologists who study fish poo describe this concept as Fish Carbon. It’s how the dissolved carbon ends up being stored in the bodies of marine organisms. This is an important process because it’s one of the ways that carbon gets to be stored deep within the ocean and also serves as a natural buffer against acidification.
But did you know that not every fish poo is equal? Some species have poo that is far more efficient in transporting carbon. Here are some marine species whose poo is pulling their weight in the battle against climate change.
They’re tiny and transparent. They’re only about the size of a human thumb but they happen to be a favorite snack of fish, shellfish, and even birds and seals.
Scientists now believe that these salps, swarming by the billions in hot spots, maybe transporting tons of carbon per day from the ocean surface to the deep sea and keep it from re-entering the atmosphere.
Salps feed on phytoplankton which absorbs carbon through photosynthesis. When salps poo, this carbon is sequestered in their coated fecal pellets that sink rapidly to the bottom of the ocean. Through this mechanism, the carbon is prevented from returning to the atmosphere and instead, is stored on the ocean floor.
Considering that they’ve been around the ocean for millions of years, they’re part of the reason why the ocean is able to absorb excess atmospheric carbon for so long.
Salps maybe transporting tons of carbon per day from the ocean surface to the deep sea
Shrimplike and small, the krill is another organism that may look unremarkable but is a “giant-sized link in the global food chain.”
Because their poo pellets are relatively larger than those of the salp, a swarm of krill can actually sequester a significant amount of carbon in their feces. Because these pellets are heavier, they can sink quickly down to the depths of the ocean where they remain locked down away from the atmosphere.
Young krill are especially important in this carbon sink cycle. Because they live deeper in the water than the adult krill, their poo is more likely to escape the ocean currents that could return the poo to the surface. Instead, it’ll sink easily until it reaches the ocean floor.
Krills can sequester a significant amount of carbon in their feces
Sea urchins eat kelp. They help clean up the bottom of the kelp forest by eating the scraps of kelp. They are considered the shredders of the ocean floor. By breaking down the tough kelp leaves, they make it easy for other scavengers to feed on the dead leaves too.
Scientists have discovered that when there are four or more sea urchins per square meter, they were able to consume up to 80% of detritus in shallow reefs. All that kelp carbon naturally went into their feces but the interesting thing is that scientists found out the “export distance” of their poo was increased fourfold.
What this meant is that sea urchin poo is easily transported across longer distances which means it has greater chances of locking the carbon permanently in the deep ocean floor.
Sea urchins' poop is easily transported across longer distances which means it has a greater chance of locking carbon in the ocean floor
Marine organisms rely on the constant fish poop to get nutrients for their survival. But it’s more than just sustenance. It’s also a way how the ocean absorbs atmospheric carbon.
— Derek Dodds, Wave Tribe Founder
Similarly, the same thing is also true for small fishes like anchovies.
When scientists studied the fecal pellets produced by northern anchovies, they found out that the sinking rates for the anchovies' fecal pellets average around 2,500 feet per day.
This means that it takes less than a day for the pellets excreted at the ocean’s surface to sink downwards to the seafloor. Given the right conditions, according to the scientists, fish fecal pellets can transport significant amounts of repackaged surface material to depth, and do so relatively quickly.
Anchovies' poop sink relatively quickly to the
But of course, nothing beats whale poop as carbon sequestering mechanism.
Whales, being the huge gentle creatures that they are, have enormous appetites. And so is apparently their poo.
Unlike other marine organisms, whale poo, or what scientists call faecal plumes, don’t sink. They float. This characteristic allows them to fertilize the oceans because their feces help fuel the nutrient cycle. More feces on the surface means more phytoplankton are able to grow, attracting other species that, in turn, feed on the plankton.
Whale poo can also store a lot of carbon. In fact, scientists have estimated that the poop coming from the sperm whale species alone can sequester 400,000 tonnes of carbon dioxide a year. That’s equivalent to the carbon emissions of 40,000 fossil fuel-guzzling cars.
Whale poop can store a lot of carbon
Healing the Ocean
The takeaway from all of these is that in order to help heal the ocean, we also need to stop the relentless hunting of marine creatures, great and small.
This is why here at Wave Tribe, we support various organizations and projects that are implementing initiatives to protect marine wildlife and protect ocean ecosystems. In fact, we’ve listed them in our Heal the Ocean page so that you can check it out if you would like to volunteer and donate to support their projects.
So the next time you’re out in the ocean surfing, keep an eye out for a whale’s faecal plume. I wouldn’t go as far as to recommend touching it but it would be awesome seeing one now that we know how important it is in the fight against acidification and global warming.