I’ve Been Invaded :(

Dateline: August 11, 2011*

Usually I get all excited finding something new in the garden or the pond. This week, I’m saddened to report that my pond has finally been infiltrated by invasive applesnails that wreak havoc on Florida’s waters. I can’t tell whether they are Island Applesnails (Pomacea insularum) or Channeled Applesnails (P. canaliculata). I haven’t seen any adult snails yet, but I know they are there because the bright pink eggs appeared in two spots on wax myrtle branches that extend out over my pond. Note that August** is Invasive Plant Pest and Disease Awareness Month.  Does that mean plants that are pests?  or pests of plants such as these applesnails.  If the former, thank goodness the Kudzu didn’t show up.

Snail Eggs of an invasive species to Florida
Snail Eggs of an invasive species to Florida

There is a beneficial applesnail in Florida that is native and called the Florida applesnail (P. paludosa). The Island and Channel Applesnails eat rooted aquatic vegetation, while the native applesnail feeds on periphyton, a complex mixture of algae, cyanobacteria, heterotrophic microbes, and detritus attached to submerged surfaces in most aquatic ecosystems [source: University of Florida IFAS]. Thus the Florida applesnail doesn’t harm the plant but the invasive ones are plant pests since they eat the plant itself.

A friend of mine spotted invasive applesnail eggs in the culvert on my block last year. I determined them to be Island Applesnails and reported the sighting to the Florida Fish and Wildlife Commission so they would be aware they were in my area since it didn’t appear on the map they maintain. They have a great identification handout with a reporting form.

I’m guessing because we had such a severe drought this past winter and the culverts were without water for so long, the snails took it upon themselves to find anywhere that had water, such as my pond. Another possibility is that with recent rains they just may have traveled with the overflow waters up and onto my place. And now they live in my pond. CURSES!

How did introduced snails get to Florida in the first place? According to the University of Florida

Pomacea insularum (d’Orbigny, 1839), the island applesnail, is the most common introduced species. This species was originally thought to be the channeled applesnail. Pomacea insularum was probably released in south Florida in the early 1980s by persons with the tropical pet industry, and rapidly expanded throughout the state. Pomacea insularum is now found in Alabama, Georgia, Hawaii, Louisiana, North Carolina, South Carolina and Texas. Introductions have occurred in Arizona, California and Hawaii. (FFWCC 2006)(USGS 2009b).”

Other types of mollusks cause problems throughout the United States: New Zealand Mudsnails are in the west; Zebra and Quagga Mussels in the Great Lakes and Midwest all of which contribute to the appoximately $1.1-120 billion per year in economic losses due to exotic, invasive species within the United States.

What can we do to prevent aquatic hitchhikers and other invasive species from moving from place to place?

In my case, I scraped the eggs into the water since eggs won’t hatch if they are inundated with water. I also routinely rake many adults out of the culvert and put them in a freezer (a humane way to euthanize since I’m no sadist and I still feel for the poor living critters). Overall, people can stop emptying aquarium water outside, wash their boats before towing, clean off fishing boots or other items before going to different water bodies. Basically, paying attention to the consequences our actions at home may have on the environment.

Invasive mollusks are everyone’s problem, so think about what’s in your own beautiful wildlife garden and be proactive in preventing contamination of natural areas by not using pet store snails even in prefabricated and ornamental ponds. Remember, it only takes one snail to infest a natural waterbody! Please help protect our creeks and streams!

Tip: Follow USDA_APHIS on twitter for daily information on what’s invading your area, how to prevent invasives and other invasive news.

*This tale was originally published by Loret T. Setters on August 11, 2011 at the defunct national blog beautifulwildlifegarden[dot]com. Click the date to view reader comments.

**Since initial publication of this article, USDA changed the awareness month from August to April.

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