While headlines focus on the destruction of once vivacious coral reefs, shellfish are the silent victims to an increasingly hostile ocean. While we rally to save marine mammals suffocating in oxygen deprived waters, shellfish species are facing extinction. While we notice poisonous shellfish outbreaks, we only see these incidents as temporary, not permanent.
Shellfish are fighting a losing battle against the effects of climate change - to such a degree that they will become a rarity.
The Whiskey Creek Shellfish Hatchery in Oregon knows the fate of the shellfish too well. In 2007, their seed stock, the young larvae that later grow to be oysters, were dying without warning and without an apparent reason. With the usual disease-causing bacteria ruled out, researchers were lost for a culprit. Finally, with close to 80 percent of their stock decimated, the hatchery found their answer: the coastal waters housing their animals were too acidic. The oysters’ ocean home was killing them.
The term ocean acidification was coined in 2003 to describe a phenomenon scientists had observed for some time. The vast bodies of water covering our planet absorb carbon dioxide which then reacts with water to make carbonic acid. While some of that acidity is cancelled out by dissolved minerals flowing in from lakes and rivers, as we put another log on the world’s coal-burning fire, the ocean could no longer keep up. Today the ocean is acidifying faster now than at any other point over the last 300 million years.
Scientists scrambled to understand exactly what was happening to oysters and other molluscs (the subset of shellfish which also includes clams and mussels) as a result of this acidification. It was apparent that oysters were struggling to adapt. Adult oysters weren’t growing as large, and larvae developed more slowly, abnormally, or simply not at all. In addition, the astringent waters were locking up the molecules that shellfish needed to form their protective shells, thick shells required to protect molluscs from parasites or unfavourable waters.
Scientists now have a greater understanding of what is happening to shellfish however, the effects of acidic water bodies vary from oysters and clams. The reason why is a mystery. Nevertheless, one thing is certain: the combination of rising temperatures and acidic oceans will negatively affect shellfish populations.
The other threat lurking beneath the waves is a suffocating ocean. Areas of oxygen-depleted water, so called dead zones, were once a natural and isolated phenomena. However, in the past ten years, these areas have grown by more than 4.5 million kilometres due to climate change. As the air warms, so too does the top layer of ocean water. Warm water can’t hold as much oxygen and that top layer blocks off air supply to lower, already oxygen-poor, ocean levels. It’s akin to trying to breathe while lying under a thick bed sheet. The effect is compounded by agricultural runoff from intensive beef farming, which floods water systems with nitrogen and phosphorus, causing algae to flourish and sap the water of its life-supporting air. While fish or marine mammals flee the oxygen-starved areas, shellfish must remain. As a result, they are the first to die. In an ironic twist of fate, our voracious appetite for one type of meat is killing our ability to eat another.
The algae thriving in these fertilizer-rich waters can also hide a multitude of different toxin-producing planktons. Those toxins, like the infamous paralytic shellfish toxin, build up in mussel, clam or oyster bodies. They manifest themselves in headlines as shellfish poison outbreaks. In reality, these outbreaks are increasing in frequency, and promise larger inconveniences than a few weeks without shellfish.
Once shellfish were one of the easiest proteins to get. The act of harvesting seafood dates back to more than 10,000 years ago. It was a simple practice of gathering them from their beds using small rakes, tongs or just by hand. Shellfish were then sold live at local markets or taken home and enjoyed by the catcher’s families. A commercial shellfish operation wasn’t much more difficult. Young oysters, for example, were grown onshore and then released into hanging baskets in the ocean. When mature, oysters could simply be pulled up to the surface and collected. Little intervention or care was needed. Now, as shellfish are fast becoming one of the most difficult proteins to catch, farm and consume, 10,000 years of tradition will be eliminated.
Yet, the decimation of shellfish won’t only result in less options at the seafood bar. Like bees, shellfish serve a vital purpose in the wider food system. Instead of pollinating the crops we eat, shellfish are a food source for many other aquatic animals in the food web. Without oysters, mussels, or clams, not only will the shellfish industry fall but the fisheries industry could follow.
Economic consequences ar also noteworthy. Declines in shellfish, particularly molluscs, will affect North American, Europe, the Caribbean, Southeast Asia, New Zealand, and other Pacific islands. The nations with little agricultural land, where wild caught seafood is ingrained in their culture, such as some island nations, will be the worst off. One study suggests that in as little as 14 years we won’t able to harvest shellfish at the same levels as today.
So is it too late to save these ocean delicacies? Some studies suggest that we would have to rein in global temperatures to within two degrees of current ones to have any hope of keeping stocks intact. Others are less optimistic, saying the ocean has already been burdened beyond repair meaning it would take thousands of years to bring it back.
Commercial operations have options: they could breed larvae that are more tolerant to the ocean’s acidic, suffocating or toxic conditions, or they could move their operations elsewhere. On a larger scale, researchers are seeing if planting vast eelgrass and kelp forests underwater could suck up some of that absorbed carbon in the oceans, in a similar way that trees on land do. Another suggestion has been to dump truckloads of lime into the water to act as a sort of Tums antacid of the seas.
These approaches may work for now, but how long until oceanic conditions become so intolerable that these options reach their feasible limit? How long until placing band aid after band aid on a gaping wound no longer ceases the flow of blood?
Losing shellfish will mean more than simply being unable to enjoy a fine meal. Losing shellfish will be another signal we are losing the battle against the death of our planet.
The ultimate solutions rely on us confronting our dependence on oil and getting serious about alternative energy sources not as a fanciful option but as a necessity. A long term solution also rests upon population control - we must create fewer mouths to feed. Yet, we should also consciously acknowledging how we feed those mouths - buying and eating only what we need. An even bigger consideration is to confront our obsession with growth, instead considering minimal economies that focus on only producing what we need, not selling us more than we want.