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Allen's Blog

Why Should We Care About Biodiversity?

E. Allen Stewart III P.E.—May 8, 2018

While kayaking in Charlotte Harbor I was discovered by this young manatee. I am not sure what fascinated him so much, but his curiosity was obvious. A larger manatee—perhaps its mother—stayed back about 50 feet and just watched. This manatee investigated every inch of my kayak, including the paddle, and we spent about 30 minutes together, until I had to leave to avoid a building thunderstorm. I would miss manatees if they disappeared, and my guess is that many of you would also. But do manatees give us something beyond the pleasure of seeing them on occasion? How do they contribute to ecological stability and what we like to call “the balance of nature.” The genes carried by the manatee contribute to the earth’s biodiversity. Just how important is it to protect them?   Photo by Allen Stewart

Recently a friend of mine emailed me with a question about biodiversity. She said she was preparing a talk for a local community group about wildlife protection and biodiversity. Her question was--

 “why should we care about protecting wildlife and on a whole, biodiversity?”

I could tell she was anticipating questions from people who might not particularly care about the fate of a few species of animals, or plants for that matter. I understood her concern, for I have heard similar grumblings from my neighbors who, for example, complain about having to slow down their boats around areas populated with manatees.

I even heard one person suggest that if there were no manatees, he would have greater freedom to run his boat “wide open”. “The sooner they are gone the better” was his comment if I recall. 


Being a Florida native, and having grown up around manatees my whole life, this talk is disturbing. But then I pondered the issue further. I asked myself—

“if manatees disappeared, would it matter? Would it place society in greater jeopardy or in some way more vulnerable to fluctuations in environmental conditions?”

My conclusion was that other than a sense of loss, I could not answer this question, and it is quite possible that very little in our technological society would change with a manatee extinction. But then it is also possible that dramatic changes could occur. Perhaps manatees in some subtle but important way have influence on fish populations or sea grass recovery, or disease inhibition, or red tide development or human mental health? We just do not know.

But before we get into discussing the value of these large mammalian species, lets first address the broader issue of biodiversity. The term biodiversity has been around for about fifty years, and its meaning and relevance has been discussed in detail by the famous Harvard Ecologist/Entomologist E.O. Wilson, who many consider the principal champion of biodiversity. Wilson notes that:

 “biodiversity is the totality of all inherited variation in the life forms of Earth, of which we are one species.”

In his latest book Half-Earth [1] E.O. Wilson not only explains the importance of biodiversity to human society, but also notes that our understanding of Ecology is seriously lacking and that decisions to eliminate species and reduce biodiversity comes with risks and often unpredictable consequences. His writings are quite popular with many scientists and some within the involved public. But sadly, this does not appear to be a large population. I have found for example in my many trips to Birmingham, Alabama to visit my wife’s family, that far more people know of Nick Saban (Football Coach for the University of Alabama) than of E.O. Wilson, even though Wilson is a native son from Birmingham, while Saban is originally from West Virginia.

It appears evident that biodiversity is a concept which gets little attention from the American public. And efforts to explain why it is important are often met with drooping eyelids, expressionless stares, glances at the smartphone, and yawns.   


So let me try a different approach. The next time you are outside, take a deep breath. That air you just took into your lungs is about 21% oxygen by volume. If it had no oxygen, or considerably less oxygen, or for that matter, considerably more oxygen, you would die. And where does that oxygen come from? As we learned in our first Biology class, it comes from photosynthesis. When we think of photosynthesis we typically think of chlorophyll and green plants—although there are some specialized bacteria which also can photosynthesize, particularly in aquatic, marine and estuarine environments. Photosynthesis of course involves the conversion of a mixture of carbon dioxide, water and sunlight into carbohydrate (sugar) and oxygen—the oxygen you breath.


So, as you are enjoying your oxygen, give this a thought. How many species of plants are involved in supplying you this oxygen? Thousands? Millions? Did that oxygen come from trees, shrubs, grasses, sedges, herbaceous plants, algae, or those specialized bacteria? All of them most likely! You can’t distinguish the source. But suppose there was not as great a diversity of plants available to supply your oxygen. Suppose further that there was only one species of plant that produced oxygen. That is, there was no diversity in photosynthesizing organism. I would think that would make you very nervous. A pest, climate change, a disease, or a massive fire may render your one oxygen supplying species extinct. This would certainly bring the issue of diversity to public attention.

Of course, the value of diversity is really not difficult to grasp, and this example of a single oxygen generating species, while a bit absurd, is sufficiently demonstrative of the need for diversity. Diversity provides durability, security and stability. Think of the occupational diversity of our society. We need doctors, and auto mechanics, and teachers, and plumbers, and engineers, and first-responders, and heavy equipment operators, and farmers, and yes, even lawyers and politicians. The absence of any of these would make us less secure, less stable. The more diverse a system is the greater its chance of persisting through time. Diversity enhances survivability.

And it is clear we need biodiversity to provide us essential resources such as oxygen and food, and clean water. I would think that would be enough to solicit protection of biodiversity. But I know what you are thinking! How much biodiversity do we need? When so-called environmentalists whine about everything from bees to golden frogs to elephants being lost, it can get a bit irritating and repetitious.


Where to draw the line? Well that is a decision we must make as a society. Are we willing to sacrifice an entire species, such as the African elephant or the Black Rhinoceros or the Florida Panther so our technological society can expand? How about a small sparrow, or a frog from the high tropics? Or perhaps a small fish like the infamous snail darter, which delayed completion of the Tellico dam in Tennessee from 1977 to 1979. The project was finally completed because of the persistence of then Senator, Howard Baker who famously said:

 “the snail darter has become an unfortunate example of environmental extremism, and this kind of extremism, if rewarded and allowed to persist, will spell the doom to the environmental protection movement in this country more surely and more quickly than anything else. ...

We who voted for the Endangered Species Act with the honest intentions of protecting such glories of nature as the wolf, the eagle, and other treasures have found that extremists with wholly different motives are using this noble act for meanly obstructive ends. ...”

From one perspective, I can understand Senator Baker’s argument. But, of course, he was not an Ecologist, and he obviously judged the small snail darter as hardly worth worrying about and it certainly was not one of his “glories of nature”. His presumption that its loss would have no impact on human society however was completely unfounded, for there was no scientific evidence to verify if indeed there was any connection between the welfare of society and the survival of this fish. It appears, for example, that no one studied in detail the snail darter’s impact upon the population of immature snails, which as its name suggests is one of its prey targets. Snails can carry the human disease Schistosomiasis, also known as snail fever or balharzia. This is a systemic disease caused by a parasite, and is often associated with chronic fatigue, imposition upon liver and kidney function, intestinal disorders, weakened immune system, and malnutrition.  Granted the snails in the rivers of Tennessee are not known to support the Schistosomiasis parasite, and it is not likely that such a spread related to increased snail populations would occur in this region. But similar relationships could exist. In more tropical regions of the world for example, damming rivers has led to increased snail populations in the static waters behind the dam, and hence increased occurrence of Schistosomiasis. It was found that the dams threatened the populations of the freshwater prawn Macrobrachium which fed upon the snails. With efforts to reclaim Macrobrachium populations, the number of snails declined as did the occurrence of Schistosomiasis.

A similar example in the United States of such a relationship is the explosion of the tick population in the northern and midwestern United States, and the commensurate increase in Lyme’s disease. There are about 30,000 new cases of Lyme’s disease registered each year, and it is estimated that if unregistered infections were included the number would approach 300,000. Treatment alone imposes about $1.3 billion annually upon U.S healthcare costs. This does not include the economic impact of lost manhours from sick days, costs of vector control, lost recreational opportunities, or subtle impositions upon family budgets. The saga of the upsurge in Lyme’s disease begins with increased populations of white-footed mice, which supply the tick population with the disease organism. The mouse has become abundant because the forest habitat has been changed through fragmentation which has resulted in extensive reduction in populations of mice predators such as owls, snakes, hawks, and foxes. This development has been exacerbated by a longer warm season assignable to climate change. And so the Lyme’s disease outbreak is largely attributable to reduction in biodiversity.

And there are many more examples of the importance of biodiversity. Consider the role of wolves which have been reintroduced to Yellowstone. There is evidence that return of the gray wolf to Yellowstone has helped enhance the Beaver population by reducing Elk browsing of willow saplings, and that the beavers have in turn enhanced water storage, making the hydrology more amenable to fish populations.

In Florida disruptions in the environment have resulted in ecological shifts, and in many cases reduction in biodiversity, which in turn has had deleterious influence upon local economies. A glaring example is the response of Lake Apopka in Central Florida to increased nutrient loading, herbicide and pesticide applications, dredging and diking, hurricanes and back pumping of agricultural water. The lake prior to these disruptions was a biodiverse system characterized by numerous animal and plant species which flourished within the crystal clear spring waters which continually fed the lake.





















Following these disruptions, from the period from 1947 to about 1965 the lake changed to a less diverse system oriented around blooms of blue-green algae (actually a bacteria known as Cyanobacteria), a fish species known as Gizzard Shad which fed upon the Cyanobacteria, and alligators which fed upon the Gizzard Shad. Much of the biological activity of the lake is now associated with the breakdown of detrital material associated with excess Cyanobacteria production, which is creating an extensive “muck” blanket on the lake bottom. Lake Apopka is located only 15 miles from Disney World and the other Orlando attractions. Imagine what the economic value of a crystal clear, biodiverse Lake Apopka would be today? Unfortunately, Lake Apopka is now pea green in color and supports an almost continuous fish kill. A decision was made years ago to reduce the biodiversity of Lake Apopka. Now the posterity of those decision makers—that would be us—are paying the price in lost dollar and lost opportunities.   


The fact is we know little about the complex dynamics of ecosystems, and it is not unusual to discover complicated interdependence of biological and physical components within ecosystems such as Lake Apopka. We know about the more obvious factors such as the relationship between plants and insects regarding pollination, and the importance of fire to many terrestrial systems. But these are simply the low-hanging fruit, the obvious and easily verified. But when we look at expanding red tide occurrences on Florida’s Gulf coast, and expansive fish kills in the Indian River and Banana River Lagoons, and toxic blue-green blooms associated with diversions of Lake Okeechobee floodwaters to the St. Lucie and Caloosahatchee Rivers, we have to wonder how this is impacting not only biodiversity, but our economic stability, our welfare and our quality of life. Every encroachment upon biodiversity is like another chamber in the Russian Roulette Pistol. Perhaps the gun will not fire if we lose the manatee, or the Florida Panther, or the Black Rhinoceros, but then it might. Can we take that chance? What will future generations think of us? How will they be impacted?

In closing, I strongly recommend reading E.O. Wilson’s Half-Earth. At first you may think he is not being realistic, but read further, it will begin to make sense. And while you are at it, read The Sixth Extinction by Elizabeth Kolbert[2]. If you are not concerned about biodiversity after these reads----well enough said!  


[1] Edward O. Wilson (2016) “Half Earth: Our Planet’s Fight to Survive” Liverwright Publishing/W.W. Norton ISBN 9781631490828

[2] Kolbert, Elizabeth (2014) "The Sixth Extinction: An Unnatural History" Henry Holt and Company. ISBN-13:978-0805092998

The 33,000 acre Lake Apopka in Central Florida is testimony to what can happen with loss of biodiversity. Because of poor management and excessive nutrient pollution Lake Apopka was changed from a crystal clear, biodiverse lake with very high recreational and economic value, to a pea-green low biodiversity lake which is in a continual fish kill and promotes the production of toxic blue-green algae (Cyanobacteria). Its economic and recreational value is de minimis, even though it is located only 15 miles from Disney World. (From Google Earth)  



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