Aquaria, Cars, and Muddy Shoes Down Under

Australia and New Zealand have suffered severe impacts from non-native invasive species as diverse as prickly pear cactus, camels, and cane toads. Some of their research on invasive species has been especially eye-opening.  Recently, an article in Biological Invasions caught my attention. It was entitled: The freshwater aquarium trade as a vector for incidental invertebrate fauna (Duggan, I.C. 2010. vol. 12, #11. 3757-3770).

The gist of the article was that all kinds of copepods, ostracods, and other tiny organisms are being shipped around the world by the aquarium trade. The researcher documented 55 incidental hitchhikers from aquaria in 43 New Zealand households. Eight were new records for New Zealand, six others were non-native species already established. Aquarium plankton – it wasn’t even on my list of things to worry about!

A couple of my other favorite examples of how easy it can be to move invasive species also come from Down Under. A researcher collected the sludge washed off cars at a car wash, added it to sterile potting media, and put it in a greenhouse. A total of 18,000 seedlings grew out including 259 different types of plants! The majority were weeds. (Wace, I. 1977. Assessment of dispersal of plant species – car-borne flora in Canberra. Proc. Ecol. Soc. Australia. Vol. 10. 168-186). Dirty vehicles are probably an important vector here, too.

Muddy boots may also play an important role.  An Australian writer tells this story. “I returned from one trip to Africa to find dried mud caked to my sandals. Examining it closely, I found a trove of organic riches: bits of straw, grass seed husks, flakes of snail shell, four seeds and some fungal threads bearing spore heads -- a forensic record of my trip lay scattered before my eyes. One of the seeds was nearly as big as a dried pea, and I thought of sprouting it to see what it was, but a tiny insect later drilled an exit hole in one side.” (Low. T. Feral Future. 1999. Viking. pg. 102).  

I'd love to have results from similar studies closer to home. Anyone know a student in need of a project? We could really use local examples to emphasize the importance of washing your vehicle, cleaning your boots, and not dumping your aquarium water. Little things like these can make a big difference in the fight against invasive species. Thanks for the heads up, mates.

Dan Hilburn