LOSS OF BIODIVERSITY

To understand why its loss is important, you must first know what biodiversity is.  The generic definition is:    the number of species in an environment and the number of individuals in each species.   To put it simply, it is the number of different species in one area and the quantity of each of these species.

Newer definitions include genetic  variation within a species  and variations between types of biological  communities  on  the  earth.   Functional  diversity  is  also  now  studied.   This is an
analysis of the biological functions performed by a specific ecosystem. This is useful in deter- mining the consequences of human impact on an area.  However, this is difficult to measure;
and it is highly  possible that important  functions of an ecosystem  may be overlooked in this measurement due to our ignorance of the processes involved (Thorne-Miller and Catena 9).

The functioning of the biosphere (or our entire planet) is dependent on the combination of all existing ecosystems.  Our very existence depends on this process functioning properly.  Every organism has its niche in the environment.  Once it is gone, it may not be able to be replaced by any other organism.  What does this mean for us as humans?  A whole host of things.

First, loss of diversity in an ecosystem can cause environmental changes.  Loss of one species may cause a chain reaction, resulting in a change to the ecosystem itself.  As we do not know what each specific organism contributes to its environment, we cannot predict how the ecosystem will be affected.  The whole ecosystem may be weakened by this process.

Plants and animals produce defense mechanisms which are often chemicals used to either repel predators or to aid in elimination of their competition.  These chemicals are vitally important to humans because many cures for human diseases have been found in these compounds.  If a species is lost due to our interference in its ecosystem, we also lose the ability to study it for possible benefits to mankind.

Secondly, the loss of diversity gives us less choice as humans.  This involves several areas.  If certain species are lost, they are no longer available to us either as food, as enjoyment, or as resources for things we may not even know about yet.  For example, if we deplete all the yellowfin tuna in the ocean, we no longer have this species available for our consumption.  If we are divers or underwater explorers, we no longer can see this fish in its own environment and receive pleasure from this act.

The fewer animals left, the fewer we can see when we interact with nature.

Other problems with loss of diversity are more subtle.  When a species is depleted so that there are only a few organisms left, the genetic diversity in the species becomes very low.  This lowers the survival rate of the species.  If all the individuals left are weak, have some form of abnormality, or are unable to survive in their environment, the species is doomed to extinction.

Extinction is a natural process that has occurred for millions of years.  The problem is that the rate of extinction has increased dramatically in recent years due to our impact as humans.  The rate of change is perhaps as damaging as the effects of the changes.  There is no time for organisms to adapt to their constantly-changing environment.

One species may be necessary for the survival of another species.  If an animal or plant is the main or only food source for another, its extinction will cause a domino effect.  Other species will die out after the original one is lost.

The oceans of the world are much more stable than the land.  Changes here usually take a long time.  The organisms which live here have adapted to meet this slow, gradual change.  They cannot tolerate drastic, abrupt changes.
 
 

ECOSYSTEM DISRUPTION

Loss of diversity in  an ecosystem can cause environmental changes.   Loss of one species may cause a chain reaction, resulting in a change to the ecosystem itself.  Every organism has its niche in the environment.  Once it is gone, it may not be able  to be replaced by any other organism.   As we do  not know what  each specific organism contributes to its environment, we cannot predict how the ecosystem will be affected.   The whole ecosystem may be weakened by 
this process.


 

There are certain species which are known as “keystone” species.  These species have unusually important roles in their ecosystems.  Fluctuation in 
their population can cause dramatic effects on the entire system.  In kelp ecosystems such as those off the coast of California there is a complex relationship between three keystone species:  the sea otter, the sea urchin,
and the kelp itself.  If any one of these organisms declines severely in population, the whole ecosystem is changed.  The otters keeps the urchin population in check.  Without them, the urchins would devour the whole kelp forest.  The kelp provides homes for many other organisms which would 
suffer if it  was destroyed.  Yet, without sufficient sea urchins, the sea otter population would decline.  It is a complex web which must be balanced 
properly for the system to thrive (Thorne-Miller and Catena 24-25).

KEYSTONE SPECIES


 

MEDICINAL BENEFITS

A second important consideration is that plants and animals produce defense mechanisms.  These are often chemicals used to either repel predators or to aid in elimination of their competition.  These chemicals are vitally important to humans because many cures for human diseases have been found in these compounds.  If a species is lost due to our interference in its ecosystem, we also lose the ability to study it for possible benefits to mankind (see Terrestrial Ecosystems for more details).


 

An aspect not  given much thought  is that the loss  of diversity  gives us less choice as humans.  If certain species are lost, they are no longer available to us either as food, as enjoyment, or as resources for things we may not even know about yet.  For example, if we deplete all the yellowfin tuna in the ocean, we no longer have   this species  available for our consumption.   If we are  divers or underwater  explorers,  we no longer  can see this  fish in its own environment 
and receive pleasure from this act.  We also no longer have the ability to study this species to see how it interacts with other species in its ecosystem.

LESS CHOICE

Other  problems with loss  of diversity  are more subtle.   When a species is depleted so that there are only a few organisms left,  the genetic diversity in the species becomes very low.   All future offspring  will bear the genes of these few individuals.  This lowers the survival rate of the species by decreasing the chances of beneficial genes in the population.  If all the individuals left are weak, have some form of abnormality, or are unable to survive in their environment, the species is doomed to extinction.
 
 

WHALING


 


A hundred years ago a whaling ship could capture 35-40 whales in one three-year trip.  Yet, in the 20th century at the peak of indus-
trial  whaling,  the same  amount of whales  was  processed in two weeks  (Cousteau 215).   This has caused the  collapse of whale populations  worldwide.   Some are  very  near  extinction.   The International  Whaling  Commission  has imposed  limits on whale hunting,  and some species are  slowly recovering  from our acts.  However,  as the species  count rises again, countries are perched 
on the  brink ready to  lift the ban on  whaling at the  first moment 
that they possibly can.  If this is done, our efforts will have been in vain for it will  take very few years  for us to be back  in the same scenario where we found ourselves earlier this century.  With more sophisticated technology like helicopters to track pods and floating factories to  process the animals,  the  whales have  little chance against our species.


 

ENVIRONMENTAL INDICATORS

Another way our terrestrial systems aid humans is that they can be forecasters of the future.   When an ecosystem  is disrupted and  other species  begin to disappear or to have problems, we can heed the warning.  A classic example is the research done within the last few years on amphibians.  There has been a major decline  in the populations  of frogs  throughout the world,  and of those which do survive many are deformed.  It is believed that because their skin is the mode  through which they respire,  they are  very susceptible to environ-
mental changes.   It is in our best interest  to discover what is causing these problems before they seriously affect humans.


 

EXTINCTION:  NATURAL VS. HUMAN-INDUCED

Extinction  is a natural process  that has occurred for millions of years so  why does it  deserve  so much attention now?   The problem  is that the rate of extinction has increased  dramatically in recent  years due to our impact as humans.  The rate of change is perhaps as damaging as the effects of the changes.  There is no time for organisms to adapt to their constantly-changing environment.  It is currently estimated that if current environmental practices are not changed, we may lose 50% of all species globally (Myers 131).

Extinction on such  a scale may be catastrophic.   In former large extinctions  in the earth’s history,  it has taken millions of years for the earth to recover.  To put this in perspective, this is many times longer than humans have actually been on the earth!  The main difference now is that, instead of having a mass extinction in one particular environment, we are losing huge numbers of species in several key environments at the same time.  Not only are we  depleting  numerous  animal and fish species,  we are also depleting  large portions of  our terrestrial plant species.  With so many plant species gone, there will be no resource base upon which to generate a recovery of animal species – including humans  (Myers 133).   As we are also depleting nutrients in our soil due to overuse,
what chance do the few remaining plant species have of sustaining life?

Refer to the Environmental Protection Agency website for details on the Endangered Species Act and other environmental regulations.  http://www.epa.gov/epahome
 
 

Marine Ecosystems

Causes of Diversity Loss

Pollution

 Why Should I Care?

Sources

Whose Responsibility Is It?