By Staci-lee Sherwood
Years ago strolling along the beach often meant collecting sea shells that had washed up on the shoreline. This was considered a passive yet enjoyable pastime. As more people started their own collection an industry started to emerge dedicated to selling sea shells from all over the world. Few consumers gave thought about how the sea shell came to be formed or what their role was in the ecosystem. Not many would have thought of sea shells as abandoned homes or worse, homes collectors were taking leaving the marine creatures that depend on them for safety essentially homeless.
Adding to the loss of their home many marine animals are finding it difficult to even make a shell strong enough to last, if even at all. Ocean acidification is wrecking havoc in many ways we rarely think about. We don't think of climate change affecting sea shells but they now show signs of the damage done. With an increase in toxins like Mercury and Carbon Dioxide being released into the atmosphere the PH balance of the ocean is becoming more acidic.
Calcium carbonate minerals are the building blocks for the skeletons and shells of many marine creatures. However continued ocean acidification is causing many parts of the ocean to become under saturated with these vital minerals. This negatively impacts the ability of some to produce and maintain their shells. If this continues those species that depend on their shells for survival will either have to adopt (not likely) or go extinct. Most sea shells are made from soft bodied marine animals in the mollusk family including oysters, clams and snails. Learn how these animals make their shells here
Ocean acidification had a slow beginning. Once the industrial revolution began, burning coal became more popular and with that added carbon dioxide in the atmosphere. The issues surrounding the use of coal are complex but the controversy is more political than ecological. Coal fired plants are well known to be huge polluters. The politics involved with their use and the jobs kept alive for coal miners has allowed this industry to trudge along when we should have replaced it with cleaner sources decades ago.
Acid rain is also caused by coal fired power plants and has devastated our forests. In layman’s terms when coal is burned it releases toxic chemicals that get trapped in the atmosphere. Those chemicals are then encapsulated in raindrops and mist and fall back down on the vegetation, land and water. When it hits the vegetation the acidity can have a burning affect hence the phrase acid rain. As it rains over the ocean it mingles with the seawater and causes ocean acidification. Carbon Dioxide also increases smog making the air we breathe unhealthy.
The average pH of seawater is 8.2 units and contains naturally occurring alkaline ions. The seawater’s pH is reduced when carbon dioxide emitted from the coal power plants is absorbed into the atmosphere, turning this into carbonic acid which reduces the water’s pH. Scientists estimate that since the industrial revolution, which revved up the use of burning coal, the ocean’s acidity has increased by 30%. There is nothing we can do to reduce that. It’s not clear exactly how the rising acidity in the ocean affects shell formation we just know it plays a role and will continue as long as it’s in use.
A pteropod shell is shown dissolving over time in seawater with a lower pH. When carbon dioxide is absorbed by the ocean from the atmosphere, the chemistry of the seawater is changed. (NOAA)
Sea Snails, sometimes referred to as ‘sea butterflies’, are studied for the affects of acidification on their shell. I first saw a Violet Sea Snail in 2008 in southeast Florida. Aside from their striking royal purple color the fragility of their shells was noticeable. On rare occasions one would wash up and special attention was paid when picking them up for a photo. No live snail was ever found in one.
As reported in pys.org in 2012 a study ‘ presents rare evidence of living creatures suffering the results of ocean acidification caused by rising carbon dioxide levels from fossil fuel burning, the British Antarctic Survey said in a statement.’ They go on to say "The finding supports predictions that the impact of ocean acidification on marine ecosystems and food webs may be significant." Click here for the 2008 study published in 2012, about acidification in the Southern Ocean
A Violet Sea Snail showing air bubbles they use to float on the water
Credit PASCAL GOETGHELUCK / SCIENCE PHOTO LIBRARY
How does the ocean’s health affect clams and in a broader view the global fishing industry that relies on them? Like oysters the clam helps filter out pollutants in water naturally making their survival more important than just a food source. It’s estimated they can filter up to 40 gallons of water daily.
The Clam helps keeps our water from becoming undrinkable
Oysters are many things to many people. For the jewelry industry they supply pearls. The fishing industry sells millions of them to consumers in restaurants and markets. For those concerned with clean water they’re invaluable in helping filter out pollutants. As oceans become more acidic all of these will be impacted although to what extent is an unknown. We won’t stop dumping into our waterways so we can imagine how the potential loss of oysters will exacerbate that problem.
We can see the cycle in simple terms; more ocean acidity means thinning oyster shells which can lead to less pearls. less oysters to eat and more polluted water. In many ways the oyster can be the poster child for why we need to move away from coal and its far reaching damage. An adult oyster is capable of filtering up to 50 gallons of water a day.
An Oyster with a pearl one of nature’s wonders
Credit Bob Beliveau
Little can be done to mitigate the effects we’re seeing. As we continue to burn coal the damage from carbon dioxide will increase. There is no such thing as ‘clean coal’ except in the minds of glossy ad campaigns and politicians seeking election. For species dependent on the ocean for survival, including our own, snazzy phrases, fast talking politicians and empty promises won’t fix the problem we created. Only our acceptance and understanding of the mistakes made and desire to change will.
Watch a short video showing how shellfish in the northwest are affected by ocean acidification https://www.youtube.com/watch?v=x7MpI9dZIjk
To learn more about acidification click here
Also published on Emagazine March 1, 2022
Also published on The good men project on March 24, 2022