Thursday, January 5, 2012

Eat the Carp! OR Invasion semantics

My friend Nick sent me a copy of this, which is currently displayed in the National Archives as part of an exhibit on  food.  Released by the US Department of Commerce in 1911.  I love ancient Swedish recipes!

This blog is all over the place!  Today's digression is non-native species, which is really not so much a digression as my meat and potatoes - freal, I don't eat meat, but potatoes (family: Solanaceae) are native to the Andes.  

Non-Native "!=" Invasive

I'm a nerd, but for those of you who are normal, "!=" is code for "not equal to".  I told you.  Anyway, saying "non-native" instead of "invasive" all the time is admittedly cumbersome, but I am nothing if not a champion for precise language.  Not all plants and animals that are transported to new places become "invasive".  That is not all of them manage to make it through:

The Four Stages of Biological Invasions ... OF SCIENCE!

1. A species gotta get from A to B to invade B.  If you're a pluteus (Geshudheit! Thank you!), you might hitch a ride in ballast water of a commercial ship moving cargo between ports. If you're a starling, you might make friends with an acclimitization society or Shakespeare. But almost invariably, you will need humans to help you move to a new place.

Get on the bus, pluteus! (Pluteus = baby sea urchin)
2.  Species gotta make their way in their brave new world.  If you're going to be a good invader, you need to be able to find food and ultimatley make lots of new baby invaders to help you invade, otherwise you're on your own.  Here's hoping your new home is just as cozy as your old one!  If you're a real goldilocks, and everything is just too hot, or too cold, or too salty, or too nitrogen-poor, I hate to break it to you, but you're just not going to be a good invader.

3. Now starts the conquering! If you've made it through the first two stages, good on ya, now comes the fun part: GO FORTH! SPREAD! Expand your range! Conquer new territory! The world is your oyster!  Often, in the case of invasive species is this literally true.  Charles Elton was a rad old school ecologist and one of the first to think extensively about species translocations.  Way ahead of his time he said,

 “The greatest agency of all that spreads marine animals to new corners of the world must be the business of oyster culture.”
DUDE! You didn't even know how right you were Dr. Elton! No, you probably did because you were absurdly smart.  I may have told you this story already, but when oyster growers used to bring oysters to new areas to try to expand their market, they often just ripped up big chunks of oyster bed and ship it across the country/ocean/etc.  If you've ever spent 5 seconds on an oyster bed, you know how many other things hide in the spaces between oysters.  So these folks also unintentionally moved lots of other critters with the oysters.  It's a sweet deal for these critters, because not only do they get their home (oyster reef) moved with them, they also get humans to take care of their home for them!  And then when you're ready, you can light out for the territory and conquer new oyster beds and other habitats!

4. Mess some $%!^&* up! Now is your chance to eat whatever looks good to you in your new home, and force other native inhabitants to leave theirs.  Take what you want, leave a mess, and NEVER APOLOGIZE!  It's just your survival imperative that compels you to wreak havok (hmm. This sounds a lot like the MO of western civilization, but that is another conversation for another day). If you are to be an ideal invader, you will find some way to cost humans money.

So the point is that not all introduced [non-native] species become invasive.  In fact - very few do.  It turns out it's kind of hard to survive 20 days in a dark ballast tank and many don't make it.  Of those that do, only a few ever manage to establish self-sustaining populations once they arrive. Even fewer are able to expand their range: gardeners will tell you how frustrated they get trying to keep their non-native plants alive. 

Interestingly, there are many that do meet all the criteria to be considered "invasive", but we like them anyway, so we don't want to hurt their feelings by calling them names - Pacific oysters, for example.  They're not native to the west coast of North America, but they were introduced to start a fishery for them here.  They spawn liberally (hippies!) and have established reefs "in the wild".  They can outcompete rare native oysters (Buhle and Ruesink, J. Shellfish Rsch 2009) but we still like them because they are commercially valuable.  So we call them "non-native" because it's true but sounds less judgmental.  

Don't get me wrong: Semantic "!=" Trivial

But here's a species that is, without a doubt, invasive:

Featured Invader of the Day: Asian Carp!
Look at 'em go! Asian carp are super-abundant in the Mississippi River
There are several species of Asian carp that have made it through the gauntlet, and are considered invasive in the US. Here's how they did it:

1. Be introduced (Check): Imported to the states for aquaculture. *Maybe* escaped during floods and hurricanes in the 1990's (apocryphal)

2. Establish yourself (Check!): Made lots of babies in the Mississippi river (see picture above)

3. Expand your range (CHECK!): Are spreading upriver toward the Great Lakes, terrifying the good folks of those waters to such an extent that electric barriers have been erected to keep them out.  But DNA collected from the waters above the barriers indicate that the fish keep on busting through!

4. Impact the environments and human enterprise (Check): Probably outcompete other native fish by being very big eaters.  They eat so much plankton, there's not enough left for other fishes.  ALSO, they are evidently a safety hazard to boaters.  Anyway, people dislike and want to get rid of them.

Eat the Carp!