[Coral-List] Exotic vs. Invasive.
szmanta at uncw.edu
Fri Feb 15 17:26:45 EST 2013
Definition of Exotic (foreign, non-native): http://en.wikipedia.org/wiki/Exotic_animal
Definition of Invasive (causes harm to non-native ecosystem).
>From Wikipedia: "An introduced, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its native distributional range, which has arrived there by human activity, either deliberate or accidental. Some introduced species are damaging to the ecosystem they are introduced into, others have no negative effect and can, in fact, be beneficial as an alternative to pesticides in agriculture for example. In some instances the potential for being beneficial or detrimental in the long run remains unknown, for instance in New Zealand. A list of introduced species is given in a separate article. The effect of introduced species on natural environments is a controversial subject, and one that has gained much scrutiny by scientists, governments, farmers and others. Not all introduced species are problematic. Those species that spread widely and create significant problems are known as invasive species."
>From US Legal definitions: http://definitions.uslegal.com/e/exotic-animal/
Exotic animal is defined by 9 CFR 1.1 as "any animal not identified in the definition of "animal" provided in this part that is native to a foreign country or of foreign origin or character, is not native to the United States, or was introduced from abroad. This term specifically includes animals such as, but not limited to, lions, tigers, leopards, elephants, camels, antelope, anteaters, kangaroos, and water buffalo, and species of foreign domestic cattle, such as Ankole, Gayal, and Yak."
Dr. Alina M. Szmant
Professor of Marine Biology
Center for Marine Science and Dept of Biology and Marine Biology
University of North Carolina Wilmington
5600 Marvin Moss Ln
Wilmington NC 28409 USA
tel: 910-962-2362 fax: 910-962-2410 cell: 910-200-3913
From: coral-list-bounces at coral.aoml.noaa.gov [mailto:coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of Ken Marks
Sent: Friday, February 15, 2013 12:38 PM
To: coral-list at coral.aoml.noaa.gov
Subject: Re: [Coral-List] Exotic vs. Invasive.
On 2/15/2013 11:26 AM, John Ware wrote:
> Ken Marks recent post concerning Tubastraea micranthus reminded me of
> an incident that occurred on a recent trip to Bonaire. A divemaster
> was bemoaning the "invasion" of lionfish. When I mentioned that the
> "poster coral" for Bonaire (Tubastraea sp) was invasive, I was
> severely chastised. Lionfish were "invasive", Tubastraea was "exotic".
> I noted that Ken Marks used both "exotic" and "invasion" in his e-mail.
> I had never thought about the distinction before.
> After Googling around a bit, I concluded that if the species under
> consideration was sort of cute, it was "exotic". If it was ugly, it
> was "invasive".
> While that is a vast oversimplification, I wonder if the coral-reef
> community distinguishes "exotic" from "invasive" and, if so, is there
> a precise definition of the difference?
In my previous post I likely used both terms merely as a means of sounding less repetitious.
In my mind "exotic" is what might also be thought of as "alien" or "foreign" in the sense that it is not native to where it is found. A zebra would be an exotic species in a Florida zoo but not on the plains of Africa. That being said, a Floridian like myself might dream of traveling to Africa to see these "exotic" animals in their native environment. This hints at a secondary definition of exotic meaning "exciting" or "unusual" which likely dates from the Victorian age (or
earlier) when "exotic" plants and animals were brought from their native lands to become curiosities in foreign lands.
Exotic species are spread in may ways, intentionally and otherwise, and through various vectors. The small dorid nudibranch /Thecacera pacifica/ which is not surprisingly (given its name) native to the Pacific, can be found rarely at the Flower Garden Banks in the Gulf of Mexico. As this is along the route of major shipping lanes the vector is likely passing ships. This little (1") species (so far) has not exploded in numbers in its new territory and doesn't yet seem to be significantly altering the ecosystem or unduly competing with or preying upon native species to the point where it would be considered "invasive".
In my mind there are stages to the "non-natural" spread of a species:
1) Exotic - The species is found outside of its naturally occurring area. The garden centers of all "big box" retailers are rife with exotic plant species.
2) Naturalized - Once a population starts reproducing itself in its non-native range I would consider it naturalized. Lionfish were intermittently released (accidentally or, sadly, on purpose) in Florida for decades but it took years for this species to reach the tipping point where it was able to effectively breed here. Once a species starts procreating I would consider it naturalized to the area.
3) Invasive - If a naturalized exotic species is very fecund and/or is aggressive in its takeover of a new habitat it becomes invasive. There have been rhesus macaques in Florida where they were released in the 1930's by a tour boat operator looking to make the "Jungle Cruise"
experience more exotic (literally). These macaques have become naturalized in certain areas where they have found it meets their needs but (to my knowledge) have not crossed the threshold where they would be considered "invasive". Burmese pythons on the other hand have established themselves in the Everglades region of South Florida and have had a devastating effect on the populations of native species (especially mammals).
I think people are willing to overlook the invasiveness of a species (/Tubastraea coccinea/) if it is "cute/pretty" and they don't notice or care about the displacement of native species caused by the invader.
There is no denying that underwater photographers like taking pictures of wrecks festooned with bright orange /Tubastraea /and so in some sense it could be argued that it is not problematic for tourism where it is found. If instead of a picturesque cup coral we were instead invaded with a nasty stinging hydroid or box jelly I think the attitude to the invader would be less welcoming.
Anyway, that's my two cents. Others may choose to comment on this or correct me as necessary.
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