Dear Guido,
 
Your point is well made, none of us walk through the world and do no harm,
but a few things must be pointed out. First, one cannot compare a veliger to
a reproductively active adult. To apply game theory to this, give an adult
Cypraea is given a value of one, and say she lays 1000 eggs a year of which
2 survive to reach reproductive age. This give an individual veliger a value
of 1/500. However, an adult cypraea could live 5-10-20(?) years making her
lifetime reproductive output 10, 40 or more.
 
The second point is just friendly nitpicking and doesn't really affect your
numbers at all. As I understand it Tridacna clams have lost the ability to
filter feed and feed only on the metabolic outputs of their symibiotic
dinoflagellate algaes, the zooxanthellae. - Aaron
 
 
>Now, for the ones chocked about the numbers:
>
>I eat more fish than meat, so:
>200 days a year one fish. Each fish, at the end of the food chain, consumed
>at least 1000 molluscan veligers : makes 200000 molluscs eaten.
>40 days in the Philippines a year, I'm eating about 30 tridacna (dailyfood
>sold by the thousands there). Each Tridacna filtered at least 10000
>veligers, which joins 300000 veligers.
>In Belgium we have traditional Mytilus edulis dishes. I'm eating at least
>30 times 100 Mytilus, which makes 3000 specimens a year. Each Mytilus
>filtered at least 500 veligers, joining 1500000 dead veligers.
>Few times a year I can enjoy better restaurants, let's say 5 times. There I
>get as introduction Littorina littorea, about 50 specimens, as a taster.
>Makes 250 extra.
>Then 6 oysters. They all killed at least 500 of their compagnions. So, 3000
>extra x 5 = 15000.
>I'm also driving about 40000 km a year. An certainly crushes during
>nightime each year 1000 Arion, Helix etc...
>Without counting my other destructive activities such as eating salad (the
>one cleaning the salad certainly killed some molluscs, each tomato killed
>certainly some molluscs), we arrive at a total of 2 016 250 dead molluscs.
>This is just for me. Because marine scientists are supposed to be fish
>eaters, and let's say we are five hundred discussing here, we speak of
>about   1 008 125 000 dead molluscs for small part of our activities.
>Who thinks that 1000 fultoni are of any significance ?
>
>An now all to Paris !
>
>Guido
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>Visit Conchology, with over 50000 names with author, 3800 indicated type
>species, 5000 conchological images, and fun with shells.
>
>http://www.conchology.uunethost.be/