Molluscs with immigration background: Neobiota

[Robert Nordsieck]

Hi there,

I have written a new page about so called non indigenous species or neobiota. There are some pretty interesting stories, how some species of snails and their relatives came to where they live today.

I know, this might only be the beginning, as there is much more to know about that subject.

www.weichtiere.at/english/mollusca/neobiota.html

Kind regards
Robert

[coyote]

Thanks for the link, Robert. It's a fascinating topic. There are a number of snail species that have been inadvertently introduced into California via horticultural shipments from the Mediterranean, and the discharge of ballast water into San Francisco Bay from foreign ships is thought to be the source of the invasive Ilyanassa obsoleta, which is displacing the native California horn snail, Cerithidea californica, from bayshore mudflats.

The only place I have ever seen a native California land snail is in a museum. I have yet to find one in the wild, yet I can see dozens of H. aspersas, O. lacteas, and the like without hardly making an effort to find them.

[Robert Nordsieck]

Hi coyote,

I think, and that also was the final delliberation of the page, that the climate in Central Europe does limit foreign snail species in their distribution and settling. That's another thing with California, which is decidedly warmer. That's also why we usually have much more problems with aquatic mollusc species, such as Dreissena, Corbicula or even Potamopyrgus, as the water is warmer and not that much affected by the climate.

Of course, foreign snail species are very very interesting, but on the other hand, indigenous snail species keep on disappearing, because we destroy the habitats. And that is sad.

It will be interesting to know, what the snail world will look like in the years to come, with global warming around the corner. I do imagine that it will be like in California with may new foreign snail species, such as the "greenhouse species" appearing and many of the more vulnerable indigenous snail species vanishing.

I also think it is very difficult to do something for those snails from the point of view of neobiota, more important it is to protect the habitats. That ought to be another page to write. Lots of work to come

As concerning the native American land snails I would love to travel to the US northwest and to Canada to have a look at them. I'd especially love to see the jumping slugs... And there are so many other interesting species. Some even came to Europe, as the quick gloss snail (Zonitoides arboreus). It's called a dagger snail in German, because its love dart looks like a dagger.

And concerning indigenous Californian gastropods - there is always Ariolimax columbianus, the banana slug, isn't there?

Kind regards
Robert

[coyote]

Yes, the banana slug will probably be around forever, because so much of its redwood forest habitat is protected from development (parks, nature preserves, etc.). The native Coast Shoulderband snail (Helminthoglypta nickliniana bridgesi), though, occupies a habitat that is popular for development into housing (although some is part of protected parkland, but not nearly enough).