[APWG] Exotics species overhyped, according to Feb.2011 SCI AMER a rticle

[Jennifer Wilson-Pines]

I don't have a paper, but anecdotally we've found that when the asian/Japanese shore crab, Hemigrapsus sanguineus moves in it pretty much decimates the native crab and even the introduced green crab alike by eating larvae. I had heard that talk about a study as to whether the shore crabs were also eating lobster larvae but don't know if it got funded. And there's also garlic mustard and the West Virginia White butterfly, http://www.nps.gov/plants/alien/fact/alpe1.htm  Jennifer Pines
---------- Original Message ----------
From: "Marc Imlay" <ialm at erols.com>
To: <apwg at lists.plantconservation.org>
Subject: Re: [APWG] Exotics species overhyped, according to Feb.2011 SCI AMER article
Date: Fri, 28 Jan 2011 13:35:08 -0500


 
-----Original Message-----
From: Tom Dudley [mailto:tdudley at msi.ucsb.edu] 
Sent: Friday, January 28, 2011 12:24 AM
To: Marc Imlay
Subject: RE: Exotics species overhyped, according to Feb.2011 SCI AMER article
 
 
Thanks for that response, Marc. I have to constantly remind people that tamarisk is not good habitat necessary for sustaining birds, it is merely satisfactory habitat that does provide usable habitat for a few species, including one endangered one. We've seen increases in SW willow flycatchers now in several locations where tamarisk is replaced by native willows.  FYI, I've attached a recent paper we did on the current biocontrol assessment program in the Virgin River.
Cheers,
Tom
 
Tom Dudley
Marine Science Institute
University of California
Santa Barbara, CA, USA 93106-6150
&
Natural Resource & Environmental Sciences
University of Nevada, Reno
 
Office: Noble Hall 1128; Lab: Noble 1250
Phone: 805-893-2911; Lab: 893-3057
tdudley at msi.ucsb.edu
http://rivrlab.msi.ucsb.edu/
 
 
 
From: Holly Sletteland [mailto:hslettel at calpoly.edu] 
Sent: Friday, January 28, 2011 11:34 AM
To: 'Marc Imlay'; apwg at lists.plantconservation.org
Subject: RE: [APWG] Exotics species overhyped, according to Feb.2011 SCI AMER article
 
I subscribe to Scientific American and was very dismayed to see that article.  It takes a highly anthropogenic view of invasive species, contending that we should only worry about them if they cause harm to the economy or health and learn to live with most everything else.  He acknowledges that some species have proven ecologically harmful, but downplays it, focusing instead on the supposed exaggeration of environmental impacts.  Scientific American is very widely read. I would hope that someone with more impressive credentials than myself would take him to task for this article in a letter to the editor.
 
From: apwg-bounces at lists.plantconservation.org [mailto:apwg-bounces at lists.plantconservation.org] On Behalf Of Marc Imlay
Sent: Thursday, January 27, 2011 5:02 PM
To: apwg at lists.plantconservation.org
Subject: Re: [APWG] Exotics species overhyped, according to Feb.2011 SCI AMER article
 
 
Regarding “the exotic plant is considered a critical habitat for endangered bird species, such as the southwestern willow flycatcher that nests in its branches.” so was the native cottonwood and willow trees replaced by the salt cedar critical habitat for the bird (There was only one listed endangered bird species, not several as implied).  We have to replace the salt cedar that we remove with the original natives. In this case one of the benefits of the native ecosystem was retained by the exotic ecosystem but other benefits were lost. The biological control can be released where the endangered bird is not present but only mechanical and herbicidal control should be used where the endangered bird is surviving, and only gradually while the native trees grow up and support the endangered bird.  The same phenomena occurred in Hawaii when the birds that endangered plants depended upon became extinct (because of us). It became necessary to retain non-native birds that the endangered plants need. We chose a less invasive species of bird to retain that worked for the plants. 
Regarding “There have been thousands of nonnative species introduced in the United States," he says, "and they have not caused one native species to go extinct.", Davis is incorrect. While it is true that invasive plant species alone on the mainland have caused few extinctions the same can be said for other causes. It is the cumulative impact that generally causes extinction. Examination of endangered and extinct species has shown that replacement by monocultures occurs over a significant portion of the ranges of about 40% of endangered species.   For example, in a paper by Sam Fuller and myself, we did a field survey of the endangered mussel, Elliptio waccamawensis, in North Carolina We found that the invasive Asiatic clam, Corbicula manilensis, replaced the native mussels which we found dead on the banks but only where the creeks were disturbed by the Army Corps of Engineers. Where the Asiatic clam had not yet reached the disturbed habitat the mussels survived. The Asiatic Clam was present, but in a much lower density, in pristine unpolluted habitat and the mussels also survived. Fuller, S. L. H. and M. J. Imlay. 1976. Spatial competition between Corbicula 
manilensis (Philippi), the Chinese clam (Corbiculidae), and the freshwater mussels (Unionidae) in the Waccamaw River basin of the Carolinas (Mollusca: Bivalvia). Association of Southeastern Biologists, Bulletin 23(2):60. 
 
[Abstract]
            Dead mussel shells and abundant living Corbicula manilensis (Philippi, 1841) were found below the confluence of the Waccamaw River with the intracoastal Waterway (Horry County, South Carolina), where the river is profoundly disturbed by human activities. Above this confluence, where the river is, in general, little disturbed, mussels were found increasingly dominant over C. manilensis, as samples were taken further upstream, until the latter disappeared. C. manilensis reappeared in Lake Waccamaw (Columbus County, North Carolina), but mussels persisted in apparently diminished numbers. The lake is almost encircled by extant and potential land development, but its floor remains negligibly damaged. It appears that C. manilensis does not (and perhaps cannot) dominate indigenous bivalves in nearly or quite natural habitats, at least in slowly moving, soft bottom Coastal Plain streams of the Atlantic drainage. Corollarily, not to disturb aquatic habitats may be man's best defense against domination of the benthos by C. manilensis. 
Cheers.
Marc Imlay, PhD,
Conservation biologist, Park Ranger Office
(301) 442-5657 cell
Marc.Imlay at pgparks.com ialm at erols.com
Natural and Historical Resources Division
The Maryland-National Capital Park and Planning Commission
www.pgparks.com
 Alien Invasion? An Ecologist Doubts the Impact of 
Exotic Species
Many conservationists have dedicated their lives to eradicating invasive plant and animal species, but Mark Davis wants them to reassess their missions
By Brendan Borrell  | August 14, 2009 | 43 

As Chew and his co-authors point out in the March issue of Restoration Ecology, salt cedar was just a scapegoat in the water wars that have gripped the Southwest. Today, many early claims have been refuted and the exotic plant is considered a critical habitat for endangered bird species, such as the southwestern willow flycatcher that nests in its branches.
In his book Davis picks apart the claim that invasive species are the second-leading cause of extinctions. He traces that meme back to a 1998 paper by Princeton ecologist David Wilcove and colleagues in the journal Bioscience, which he derides for being based on the "opinions" of field researchers. Moreover, most species said to be imperiled by invaders were located in Hawaii and on other islands, not the mainland U.S., where he is skeptical that alien species can gain a foothold. "There have been thousands of nonnative species introduced in the United States," he says, "and they have not caused one native species to go extinct."

 -----Original Message-----
From: apwg-bounces at lists.plantconservation.org [mailto:apwg-bounces at lists.plantconservation.org] On Behalf Of Craig Dremann - Redwood City Seed Company
Sent: Tuesday, January 25, 2011 8:32 PM
To: apwg at lists.plantconservation.org
Subject: [APWG] Exotics species overhyped,according to Feb.2011 SCI AMER article
 
Dear All,
 
February 2011 Scientific American article, page 74-77 "A Friend to Aliens,
by Brendan Borrell, an interview with Mark Davis of Macalester College in
St. Paul MN.
 
Sincerely,  Craig Dremann
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