Species species of the Week week #2 OR Emily's FAVORITE Tautonym

Gemma gemma

(The Amethyst Gem Clam)

As it's at least supposed to be a molluscan marine blog it seemed worthy to start (1) with a redundant local marine mollusk.  Unfortunately, it turns out that very few, if any, tautonomical invertebrates are native to the Pacific Northwest (2).  So why not a non-native? It turns out this one is also my very, very favorite tautonym.

Figure 1. Peterson (of field guide fame) refers to G. gemma as, "a handsome ... clam, easily overlooked because of its small size".  Just so, sir.  Just so.

Photo Credit: Fisheries and Oceans Canada. Melissa Wong.

In addition to being the name of my wireless network, Gemma gemma (3) is the diminutive Amethyst Gem clam (Disambiguation).  These tiny bivalves are native to the east and Gulf coasts of North America, from Nova Scotia to Texas. They were introduced along the west coast of the US around 1960, but have only recently become very abundant in San Francisco Bay - but hey, what hasn't these days?! Am I right, folks?! (<---- NOTE: That was an excellent/horrible invasive species joke.  Insert rim shot here ... plz.)  

But seriously...

Ted Grosholz (UC Davis) tried to figure out why the gem clam population didn't really take off until decades after it was actually introduced (4).  It looks like the gem clam populations used to be held in check by competition (Figure 2) with native clams of the genus Nutricola (which I'm pretty sure are referred to as "Nut" clams).  

Figure 2. Schematic depicting San Francisco Bay pre-Green Crab Invasion (5).  Native Nutricola spp. (Pink, Yellow, and White individuals) originally kept non-native Gemma gemma (Green individual) at low abundances by eating up all of the food (phytoplankton represented by dinoflagellates, chain-forming and pennate diatoms and coccolithophores) leaving only scraps for poor G. gemma. 

Gem clams were kept at such low abundances that they were not, apparently, worthy of much notice or concern.  That is, until the arrival of the [non-whimsically named] European green crab, Carcinus maenas, which came to SF bay as a stow-away in the late 1980's.  The invasive crab, embracing the gastronomic culture of its host country, prefers to eat the biggest thing is can get its little green claws on, which in SF bay is the native Nutricola spp. The tiny gem clams get overlooked - lucky Gemma gemma devils!  That means no more selfish native clams hogging all the delicious phytoplankton (Figure 3)! Time for tiny gem clams to make tiny gem babies! 

Figure 3. My, how the tables have turned!  Schematic representing San Francisco Bay post-Green crab invasion.  Crabs (lower left) preferentially consume native Nutricola spp. (lonely yellow individual), freeing up more food for non-native gem clams (prolific green individuals) to make gem babies! 

Cool, huh?!  In many cases like this one, non-native species are present at low abundances for years after they are introduced, leading people to be all like, "ohhhhhhh....whateverrrr...it's no big deallll...I mean, who cares about some dumb clam anyway..."  And then something changes.  Maybe the non-native population develops a key adaptation that enables it to make more babies than before, or something else in the environment frees up resources (*cough, cough* I'm looking at you C. maenas), and the population of the non-native explodes and messes things up for EVERYONE.  And people are all like, "whaaa!? But how could we have known!?"  And I'm all like, "because it happens every time!"  Well, not every time, but surprisingly often. 


So called "lag times" are a pretty common property of biological invasions, and one extremely good reason that, notwithstanding any aesthetic arguments(6) for the moral equivalence of human and non-human invasions, all introductions of non-native species deserve to be treated with caution. 

References and miscellany:
(1) Yes "start" more than a month later, this is the first second species species of the week week. I did warn the one of you that reads this that these would be irregular and unlikley to actually appear on a weekly basis.
(2) I'm tempted do some arm waving here about how this probably has something to do with the idea that the tautonym species are so-named because they were the first of the genus to be described, and most of the marine genera in the PNW were first described in Europe or the east coast of North America.  But that arm waving will only appear in small print in the foot notes.
(3) On the pronunciation of Gemma gemma: "gemma" comes from Latin for "jewel". I assume it SHOULD be a hard G if you're being true to Latin pronunciation, but I have only ever heard it pronounced with a soft G, presumably in honor of the common name - which also pretty much comes from Latin for "jewel" but has since been bastardized.
(4) Grosholz, E., (2005) PNAS. 102(4): 1088. 
(5) If you have to look this game up, and don't have age as an excuse, your childhood was misspent.
(6) Drew Christie is a great Seattle animator and illustrator whose work I actually really like, but this piece got under my skin (really really far under my skin), for making a tenuous aesthetic (but it's cute!) and moral (humans are invasive too, who are we to point the finger?!) argument that manipulates feelings about a legitimate conservation issue.

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!