Friday, 6 December 2013

The Butterfly Effect and Ocean Acidification

Will the Sea Butterfly be the victim of ocean acidification that causes a collapse of the ocean's food web?

Mathematicians working in physics, engineering, and biology have developed the concept of chaos theory. In a nutshell, this says that some processes are incredibly sensitive to the conditions at the time they start; things can turn out very differently with each tiny variation at the beginning.

This lead to the term, the Butterfly Effect, coined by Edward Lorenz (1917-2008) and creating the idea that much in nature is unpredictable.

I’ve always been intrigued by the theory; fascinated with such an absurd concept that seemed beyond proof and yet so believable. Could the beating of a butterfly’s wings really start the chain reaction that eventually grows into a whirlwind that destroys us all?

 The elegant sea butterfly is actually a tiny swimming snail

A few months ago I ran across an article in the Smithsonian Magazine about one of the most charming creatures in the ocean. Sea butterflies are tiny mollusks, ‘snails’ in fact, that are so light they are able to either fly through the shallow waters of the oceans or glide hanging upside down on the water’s surface using their foot. From a biologist’s perspective they are quite beautiful and very ‘cool’.

Called Pteropods, these fragile creatures are only a few millimeters long and have nearly transparent shells. Their shells look like those of their terrestrial cousins but are incredibly thin to make fluttering through the ocean possible. 


Sea butterflies number in the trillions from the tropics to the poles and eat enormous quantities of microscopic plankton, mostly plants, by entangling it in fine mucus ‘fishing’ nets. Their diet is the stuff that makes up the foundation of the ocean food pyramid and the sea butterflies are the first step in converting these plants into food for larger animals. At night many hunt at the surface and return to deeper water each morning.

Surprisingly, ocean food pyramids are rather short. Four or five steps usually gets to the top, to what are called the ‘apex’ predators. Of real importance is the fact that there is a lot less food at each level of the pyramid. Really large animals like many whales can’t find enough energy at the top and so take a shortcut and eat tonnes of plankton like tiny shrimps and of course, sea butterflies.

But man started a time bomb ticking at the end of the 18th Century when we began burning fossil fuels to power our industry and fulfill our dreams. In the USA, more than 90 percent of greenhouse gases come from fossil fuels. We now produce about 40 thousand tonnes of carbon dioxide every minute, double the earth’s ability to deal with it naturally.


The sea has been very obliging in the past and absorbed through biological and chemical processes about half of all the carbon dioxide that was produced since the industrial revolution. As the carbon dioxide combines with water molecules a chemical called carbonic acid is formed and this makes water just a little less alkaline and lowers its pH in a process called ocean acidification.

The effects of ocean acidification are already measurable. Emily Frost and Hannah Waters of Smithsonian’s Ocean Portal (May, 2013) report that the shells of sea butterflies in the arctic have already begun dissolving in the more acid sea. Now it is true that not all sea butterflies have shells, but unfortunately, those that don’t (the Gymnosomes) are predators of those that do. The shell-less species will perish along with the shelled ones as carbon dioxide levels continue to rise. Their loss may have a staggering impact on whales heading north to feed after calving in the tropics.

 Sea Butterflies that don’t have shells (the Gymnosomes) are predators of those that do

Whales may be the first alarm bell ringing as the effects of acidification and the loss of tiny shelled creatures spreads across the oceans. Closer to the equator are squid, anchovy and herring fisheries and the even larger tuna and mackerel they support.

Many species like the giant whale shark and basking shark are totally dependent on the lower levels of the food pyramid. The commercial fisheries most at risk supply about 40 percent of the protein to two thirds of the world’s population.

 The huge Basking Shark feeds only on very small fish and plankton

The plankton that is carried over the world’s coral reefs by ocean currents is the bringer of life; swarms of tiny creatures are caught by corals, sponges, clams, and colorful fish. The collapse of the coral reef food pyramid will be a disaster for the 200 million people that depend on its productivity for sustenance. 

Will everything in the ocean die?

The answer is definitely not. But the future ocean will be a lot different to the one we know today. There will be winners and losers in the race to survive. Those species unable to find suitable food will of course dwindle and face extinction. Those that shift to other prey species will bring enormous pressure to bear on their new food and cause the balance of the whole ecosystem to shift even farther. 


A few years ago (2009) , Martin Scheffer of Wageningen University in The Netherlands together with a number of other scientists published in the journal Nature.
They found that many things from climate, to nature, to finance show similar behaviours as they approach a point of change called a ‘tipping point’ where processes strike off in an unpredictable direction. "It's increasingly clear that many complex systems have critical thresholds -- 'tipping points' -- at which these systems shift abruptly from one state to another," write the researchers.

"The information comes at a critical time -- a time when Earth's and, our fragility, have been highlighted by global financial collapses and concern about rapid change in climate and ecological systems."

So what about the sea butterflies? We set an unknown course when we started to burn fossil fuels more than 200 years ago. With that new found power we remade the world and our lives to suit us but in the process we have ‘tread’ on the lives of a few tiny species that really do matter. They are the underpinning of much of our future and the lives of millions. We could not see the future then and perhaps we wouldn’t have cared anyway.


How ironic that when Edward Lorenz coined the expression, Butterfly Effect, in 1969 he described without knowing the  biological  cataclysm that would  throw the world into chaos  80 years later.

In the crystal waters of the Andaman Sea where whale sharks come to feed I can just see tiny sea butterflies a few centimeters below the surface. Their wings are beating now but for how much longer? Will it be their loss that really starts the chain reaction that eventually grows into an environmental ‘whirlwind’ that destroys us all?

If you are interested in some of the latest topics in ocean conservation check out some of the other posts on this site.

Gerry is a Malaysian based marine ecologist, Research Fellow and Advisor to the National University of Malaysia, and marine consultant to the Andaman Resort, Langkawi.

No comments:

Post a Comment