IS DESTROYING THE ECOSYSTEM?
of my grandsons brought me a book last week and said, "Grandpa,
I want you to write about this. I think it's important." I looked
at the book, "The 10 Most Destructive Ecosystem Invaders"
(by Lisa Cheung), and decided that maybe it was.
is part of a series by Rubicon Publishing that focuses "primarily
on educational publishing for K-12." I like their stated goal of
improving "the literacy skills of all kinds of readers ... by creating
material that is bold, creative and engaging, but also has instructional
has excellent photographs and catchy modules of information. In this
book the ecological facts are enlightening and entertaining. Not everyone
will agree that the 10 species chosen are the "most destructive"
ones. Indeed, the author notes that opinions will vary about which species
should be on the list and in what order. Your opinion might be influenced
in part by where you live, but the critical point is that ecosystems
worldwide are under siege by destructive invasive species.
listed in the book include some I have written about before. For example,
the zebra mussel. Listed as no. 10, it is an invasive species accidentally
introduced from the Black Sea into the Great Lakes via cargo ships.
One of the negative impacts is on native mollusks, which the zebra mussels
outcompete. I can tell you from experience that these little shelled
intruders have sharp edges, and when you step on them barefooted in
a lake it hurts.
I have talked about is the cane toad (aka marine toad) from tropical
America that has been introduced to Australia and other regions with
devastating environmental effects. Not only do these giant toads, which
can reach over a foot in length, eat other amphibians they are even
deadly to some would-be predators. A cane toad has huge glands on the
top of its head that produce poisonous compounds. An animal that tries
to eat one of these invaders ingests toxic chemicals. When cane toads
are introduced into a habitat where native predators have no experience
with them, the results can be deadly. The cane toad is given the rank
of No. 3.
tree snake is listed as No. 2. This quintessential invasive and destructive
species, found naturally in the Australian and Indonesian regions, was
unintentionally introduced onto the island of Guam in the western Pacific
during World War II. It has become such a serious threat to local wildlife
that Guam's native forest birds have been declared "virtually gone."
At least a dozen birds known only from Guam are now extinct.
lists the Asian long-horned beetle as the No. 1 destructive ecosystem
invader in the world. Native to China, these black and white beetles
have been introduced in Europe, Canada, and the United States. The noticeable
impact of the invasive beetles is the destruction of hardwood trees.
The larvae burrow into native trees and eventually kill them because
trees outside the beetle's geographic range have no natural defenses
alien species become rampant pests whereas others do not remains a mystery.
of all accidental or intentional releases of alien species would reveal
that most never survive for more than a few generations if that long.
may persist but never reach high population levels; they simply become
an inconsequential part of the flora and fauna of a region. For example,
many southern cities have small, but persevering, colonies of inoffensive
gecko lizards native to tropical Africa, Asia, and the West Indies.
To my knowledge, none of them have become predators or competitors of
any of our native species.
quibble about the book's top-10 list, rearranging the order or substituting
one invasive species for another. But there can be no argument that
the uncontested, hands-down, indisputable leader in ecosystem destruction
is humans. It's important to remember that.
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