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Date: Sat, 8 May 1999 20:30:17 -0700 (PDT)
From: <[log in to unmask]>
To: Art Weil <[log in to unmask]>
Subject: Re: Question
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Hi Art,
 
Here in California they have quite dramatic effects.  For example, both
have been implicated with short-term spatial shifts in the distribution of
molluscs from the Oregonian and Californian provinces since the
Pleistocene.
 
In 1998, I was observing several fish species that are
rarely seen north of Pt. Conception (the major biogeographic barrier that
separates the above-mentioned regions).  Along with adult and juvenile
fishes, plankton tows netted lobster and mantis shrimp, neither of which
naturally occur in central California.  Certainly veligers were making
their way northward.  We won't see the impact until juveniles get large
enough, but certainly previous ENSO events have carried subtropical and
warm-temperate molluscs northward.  I am in the middle of co-authoring a
manuscript on several range extensions in California, and ENSO events are
a likely mechanism of transport.  The mounting evidence of increasing sea
surface temperatures this last century also contributes to the northward
shift of warmer water species.
 
Also, ENSO events impact the coastline to depths of 100 m (really warm
water), so subtidal species are definitely impacted.
 
Do La Ninas bring more cold-water species south?  I think we'll be able to
detect that in a year or two.
 
Cheers,
Steve
 
>         What effect does the El Nino and La Nina shifts in water temperature
> have on mollusks? I don't imagine there is much change deep down, but
> what of species dwelling only slightly below tide lines?
 
Steve Lonhart
Department of Biology           Office:  (831) 459-4026
University of California        FAX:     (831) 459-4882
Santa Cruz, CA  95064           email:   [log in to unmask]
 
WEBSITE:  http://www-biology.ucsc.edu/people/potts/lonhart/