Call Me Trimtab

critical pathBy Mary Ellen Hannibal

This past Friday I was out in the tide pools at Pillar Point in Half Moon Bay, helping Julie Waters and other folks from the Fitzgerald Marine Reserve count nudibranchs.  Nudibranch means “naked gill” and most species look like a piece of drag queen, flagrant blogs with feathery decorations that sit there as if enjoying their own practically immobile parade.

I’m not very good at finding them though on a previous expedition I spied one of the more common species, which looks like a blob of white chewing gum.  Nudibranchs are hermaphrodites and while it takes two to tango, each one is capable of being either mom or dad.  The white blob I found was sitting there next to a spooled white thread of eggs, recently produced.  I thought he/she looked mighty proud.

Nudibranchs are among the myriad invertebrates that do the heavy lifting at the bottom of the food chain in the ocean.  Quivering and exposed as they are, inverts are particularly vulnerable to ocean acidification.  To say nothing of warming temperatures.  In pursuit of cooler waters nudibranch species here are migrating North to Duxbury Reef in Marin, where a cannibal nudibranch gobbles them up.  The cannibal is an invasive, and the native nudibranchs didn’t evolve alongside it, so have no defenses to resist its slurping onslaught.

This sort of torquing of the relationships in the food chain is among the forces identified by Anthony Barnosky and colleagues in a paper I give a lot of worried thought to:  “Approaching a state shift in Earth’s biosphere.”  Basically the paper addresses the issue of the “anthropocene,” or the fact that human impacts now shape geological as well as atmospheric forces.  The changes we are wreaking  could send ecological systems over a tipping point, in which they would “shift abruptly and irreversibly from one state to another.”  Suffice it to say we won’t like the new states very much.

As the clouds move overhead at Pillar Point so does the color scheme of water at the surface and in the depths shift.  Now I am transfixed by a hermit crab and a gigantic pink sea star sitting under a reef.  Now the water looks electric above and black below.  Big radar globes on the cliffs above remind me of Buckminster Fuller’s geodesic domes.  Fuller’s tombstone reads “Call me trimtab.”  A trimtab is a small rudder on the bottom of a bigger rudder, and this devise by increments is able to set the course of a big ship.  Fuller suggested that small, directional changes can have enormous impacts.  David McConville, the president of the Buckminster Fuller Institute, uses mob-grazing as an example:  by simply shifting the timing and duration of cattle feeding on the landscape, instead of decimating biodiversity, cows can actually stimulate the growth of native grasses, in turn inviting mycorrhizal fungi to do its thing and draw carbon out of the atmosphere and put it back in the ground (where it belongs).  The dirt thus created is rich and dark and grows more nutritious forage, and everybody wins.  Thus some moveable fencing and a single cowboy on a huge ranch can have a trimtab effect and the state shift disaster is averted.

In the making small changes to big effect category, we might look to the nudibranch.  Their fancy fringes are in fact extensions of their digestive systems, in which they embody poisons absorbed from their prey.  These they wave around in provocation or warning to any bigger creature wanting a quick slug snack.  Over the eons, these brain-challenged wonders have figured out how to take what kills them and use it to help keep them viable.  Creative little buggers – we have a lot to learn from them.





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