Despite the title, non-native or alien species are no joke. Non-native species are sometimes introduced to new regions that are outside their natural range, often by human activities. Most often, these intruders are unable to survive the unique environmental characteristics of the new habitat, and do not successfully establish a new population. Occasionally, however, a non-native species will successfully colonize a new area. When that is the case, the new species may have a negative impact on the local diversity and may be termed “invasive1.”That is the case with Littorina littorea, a European snail that has successfully colonized the East Coast of North America, and has been found on occasion here on the West Coast2. This periwinkle is sold in seafood trade and was likely introduced here as a consequence.
But what do periwinkles have to do with alien lobsters? Well, this year Biology 326 was lucky enough to adopt an Atlantic lobster named Lucky from a local family. The Calkins family caught Lucky in their prawn trap and generously offered to donate her us so we may use her to study the impacts of non-native predators off our coast (more on Lucky’s capture here).
We decided to explore the potential effects of native and non-native predators on both native and non-native prey. We focused our efforts on four species: Atlantic lobster (Lucky – non-native), Dungeness crab (BIG DAN – native), European periwinkle (non-native) and black turban snails (native). Our goal was to determine which predator, Lucky or BIG DAN, is scarier to native and non-native snails. In order to do this, we placed each snail in a glass bottle filled with sea water that smelled like either Lucky or BIG DAN. We then timed how long it took each species of snail to react to the scent of the predator and climb out of the water to safety.
We expected that native snails would react quickly to BIG DAN since the two species have co-evolved and black turban snails should have enough experience to recognize the smell of Dungeness crabs and run when they are near. However, since the periwinkles don’t have experience with Dungeness crabs, we expected that they wouldn’t be afraid of BIG DAN and would stay put. We hypothesized the opposite when it came to Lucky – periwinkles would know that she was a threat because of their common history, whereas black turban snails would not.
As we expected, native snails were scared by BIG DAN, and crawled out of the water quickly when they smelled him. Non-native snails, not recognizing the threat, crawled out of the water slowest when exposed to BIG DAN’s scent. However, neither native nor non-native species of snails were afraid of Lucky. I guess lobsters aren’t that scary after all. Sorry Lucky!
- Mack, R.N. et al. Biotic Invasions: Causes, epidemiology, global consequences and control. Ecological Applications, 10(3): 689-710.
- Littorina littorea. The Exotics Guide: Non-Native Marine Species of the North American Pacific Coast.