Wednesday 15th April, 2009 Posted: 17:31 CIT (22:31 GMT)
It is unclear exactly what long–term impact the massive introduction of iguanas will have on the ecosystems of the Cayman Islands.
What role will these lizards play in altering the biodiversity of these islands?
Will they cause certain native plants to go extinct, triggering other negative biological changes in our environment?
One thing is certain.
Any animal that does not play a supporting biodiversity role in the wild, and freely multiplies without checks or balances, will eventually create havoc in any ecological system.
With the extinction of the Caiman crocodile from our shores, Cayman’s ecosystems have no natural predators to keep iguanas in check.
Allowing iguanas, blue or green, to artificially multiply en masse and unhindered may be a biological disaster in the making for these islands. The well–being of humans occupying these islands is also at stake. Anything seen as a pest will have a negative impact on human life.
The random, thoughtless introduction of foreign species into once pristine environments has a history of creating biological disasters. One prime example is the introduction of the Brown trout into the streams of New Zealand. In 1867, this fish was introduced for sport anglers. It was not until the 1990s that the full environmental impact was noticed. This fish significantly altered the distribution of local fish, permanently changing the food webs of the streams.
The ecology of Yellowstone National Park suffered greatly when its top predator, the wolf, was hunted to the point of extinction in 1925. Elk numbers increased dramatically, which had a negative impact on other plant and animal species. Willows and beavers began to disappear. Coyote populations increased and ground squirrels dwindled. Eagles and hawks almost vanished. Fortunately, these negative biological changes were corrected when the wolf was reintroduced some 70 years later.
Many of our large indigenous mahogany trees are disappearing because of invasive plant species. I have witnessed majestic 30 and 40–foot tall mahogany trees wilt and die under the impact of an out of place vine that literally choked them to death. It is not clear which local animal or plant species the ubiquitous, uncontrolled iguana will choke first, but the evidence will be available sooner than later.
This letter is not encouraging the reintroduction of the Caiman crocodile as a top predator, which would have a negative impact on human beings as well, but it questions the wisdom of the wholesale introduction of iguanas into these islands. They may very well be our ‘Brown trout’ or ‘Yellowstone Elk’ of the future. Individuals concerned about the importance of biodiversity in ecosystems are encouraged to read the following document: Millennium Ecosystem Assessment, 2005. “Ecosystems and Human Well–being: Biodiversity Synthesis.” World Resources Institute, Washington, DC. (Available at www.millenniumassessment.org)