Dear everyone,

 Apologies for coming in rather late on this; just wanted to add:

 1.  I've often noticed the absence or near-absence on beaches of species
 which are locally very common.  Just to give two instances, I was recently
 collecting shells on beaches in Thailand with lots of Littorina and
 Nodilittorina on the rocks at either end, but found only one dead shell in
 many hours of searching; and I remember a beach in Brittany with a large
 rock outcrop in the mid-tide zone covered with Littorina and Patella, while
 the beach produced none (I spent a long time looking because red Littorina
 littorea were fairly common there, and I wanted
 some examples), but had plenty of bivalves and Actaeon.

 2.  Another cause of shells being found a bit out of context is beach
 replenishment.  I recall a beach in Greece with a wonderful range of
turrids
 and other slightly deeper-water gastropods resulting from replenishing with
 dredged sand after the beach had been messed up by building work.

 That and other cases notwithstanding - and one needs to be alert to other
 possible explanations especially if a shell is the kind of thing people are
 likely to collect or move round - nonetheless  in more than 99% of cases
 finding a shell on a beach is good evidence that it's likely to occur in
the
 area.  The converse, however, doesn't hold - absence of a species on
beaches
 in an area shouldn't normally be taken as evidence of absence without
 attempts to find the species live in likely local habitats.

 But beach samples aren't remotely representative - they are often strongly
 sorted for shells of particular sizes and shapes, and for heavier or
lighter
 shells, depending on waves, currents, tides and winds, and which part of a
 beach one searches.

 Bas Payne

>> 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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