Believe it or not, the tough Nerita are quite sensitive to oil spills and
the chemicals used to clean them.  Nerita albicilla, common as pebbles in
the sand, disappeared for 13 months in the Hong Kong area after a spill.  A
similar thing happen to Theodoxus in the Middle East and when the chemicals
were applied beyond the spill area, they also wiped out the snails in that
area.  This all makes sense because of the feeding habits of nerites.  Most
graze on the algae/diatom patina on intertidal rocks.  They tend to feed
with the receding tide and an oil spill would be nicely spread down the
surface of the rock as the tide fell. Along comes the nerite feeding on oil
flavored algae.

Tom E

> -----Original Message-----
> From: Conchologists of America List [mailto:[log in to unmask]]On
> Behalf Of Ross Mayhew
> Sent: Tuesday, September 02, 2003 5:53 AM
> To: [log in to unmask]
> Subject: Thanks! - and molluscs as "indicator" species
>
>
> Thanks, Harry and Wesley!!  This is useful information.
>
> I am wondering if this species might be an "indicator species", that
> indicate when an ecosystem is starting to become unbalanced or unhealthy
> - like the proverbial canary in the mine?   Does anyone know of other
> molluscs that are species quite sensitive to ecosystem disturbance, and
> whose dissapearance or dramatic reduction in numbers might be taken as
> an Early Warning sign of developing problems?   I know many Unionids
> fall into this category, but what about marine species or fresh
> water gastropods?
>
> From Canada with curiosity,
> Ross M.