Sea star (Image Credit: Daniela Ginta)

Sea star (Image Credit: Daniela Ginta)

Bodies of water all around us, from lakes and rivers to seas and oceans, hold the evidence that nothing disappears, everything transforms. The true state of the oceans or the big interior lakes we depend on is hard to picture, and often their immense blue-green waters reveal nothing worrying unless you go below the surface where things can get murky, literally and otherwise. That means we have to pay attention to the signals we get from the depths where things happen silently. In other words, we have to mind the proverbial canaries in the coal mine (the aquatic version).

Humans have been influencing the state of water over the last century, and they continue to do so through various activities: overfishing, chemical or plastic pollution via improper garbage disposal, noise pollution, climate change leading to acidification and increased temperature. The latter two may seem minimal yet they cause changes in marine wildlife that can have disastrous consequences.

Such was the case in the recent die-off of sea stars all along the western coast of North America. It made the news on more than one occasion as millions of sea stars kept dying.

The cause of what is now known as sea star wasting disease was a mystery – with experts hypothesizing global warming or even the Fukushima disaster as potential factors – until November 2014. That’s when researchers found the culprit: a virus from the Parvoviridae family, also known as the densovirus.

The most plausible explanation for the outbreak was ocean acidification that lowers viral resistance in sea creatures such as sea stars. The death of sea stars leads to an increased population of sea urchins and these, in turn, devour more kelp than is acceptable for a balanced ecosystem in which fish and other marine life use it for shelter and protection from predators.

Sea stars form a keystone species in the marine ecosystem, meaning the strength of their population directly affects other species such as algae, snails and prawns. Mass die-offs of sea stars can cause these other species to disappear in certain areas, and it can also affect some populations of kelp-dwelling fish that humans consume.

As for what those fish eat, research shows that microplastic is now on the menu. Microfibers, derived from synthetic fabrics that contain petroleum products such as polyster and nylon, have recently been identified as a possible threat to aquatic wildlife. Due to their minuscule size, microfibers can end up in the water supply and be consumed by fish that are, in turn, consumed by humans.

When it comes to seafood, humans are at the top of the food chain, but that chain is steadily souring from what we are doing to the planet. Pollution, overfishing and climate change are not only impacting the marine habitat, they’re also impacting us on land. The future of our water is, like the rest of the planet, in our hands.

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