On Fri, 24 Mar 2006 09:03:56 -0800, ronald noseworthy
<[log in to unmask]> wrote:

>Hi, everyone!
>
>While I was preparing a database on the mollusks of Jeju
>Island, I realized that I had a lot of records of dead
>material from the many beaches on this island.
>
>What is the relationship between the dead shells found on
>beaches and the living populations of those species?  Would
>the dead material be an accurate record of the living
>mollusk fauna of the adjacent area?  What exceptions would
>there be?
>
>I have searched the Conch-L archives but found little on
>this subject.  Any assistance you can offer would be greatly
>appreciated.
>
>All the best from Korea!
>Ron Noseworthy
>
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Aloha,
Beached & hermit crabbed shells offer a working knowledge of a areas
molluscan fauna. Beached material represents time-accumulated debree while
hermits show shells that are rarely found alive to commoner species. So what
are the exceptions?

1)In Hawaii non-native species have appeared washed-up along Ewa Beach on
Oahu. Cypraea annulus for example has appeared in beach drift with posterior
& anterior holes. Why? Simply put Waikiki tourist boats frequent this
coastline & often shell leis are tossed overboard as a token to the "sea
gods" and the broken pieces are eventually washed ashore. Note the drilled
holes for stringing purposes.
2)Some Panamic offshore islands have common Indo-Pacific shells accumulated
in beach drift but no living representatives. Why? El Nino. Some years the
warmer currents prevail bringing in veligers of non-Panamic species. But a
sustained population is needed to sustain a species & when the currents
switch back the alien species quickly die off. The Green Trevaly Jack, a
common California fish species is sometimes found off Kona, Hawaii when the
water's mean temperature cools bringing in the pelagic eggs to settle.
3)Some local governments transplant species for commercial purposes. In
Hawaii during the late 1950's Trochus niloticus was introduced along with
the Golden Blueline Snapper(Ta'ape in Hawaiian). Though the trochus
disappeared the Ta'ape unfortunately flourished & now competes too well with
much more desired species. Thus the fishermen dub them "golden rubbish".
4)Other species can be transported. In Oahu, Hawaii Chama macerophyla was
introduced from barge hulls in Pearl Harbor. Guam based submerines have
brought in many alien species to the surrounding area off Pearl Harbor. And
Cypraea semiplota, indigenious to the Pearl Harbor area was recently
introduced to Lahaina via the subs now parking offshore Lahaina, Maui. Wind,
waves, currents brought Littorina scabra to the Hawaiian Islands atop floatsam.

If you're in a remote area some of these factors wouldn't apply.
Understanding a area's marine life can be regarded as a "shot in the dark".
Many factors do apply. As with everything good research & a open mind goes
far.   CHRIS:)

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