Rust To Rust

Microbiologists tend to look on the bright side of things. For them, there's no such thing as death, just the introduction of a new food source. "While the Titanic was new", muses University of Regina microbiologist Dr. Roy Cullimore, "it was very animate with human life. Then there was the tragedy of death. Now essentially another biomass is taking over the ship, the rusticles."

Looking on the bright side -- Cullimore with consortial friends
These rusty icicles, immortalized by the film Titanic and now as emblematic of sunken wrecks as cobwebs are of dusty attics, represent more than decay to Cullimore. Cullimore believes that because of their unique structure and the consortial, or communal, living habits of the life forms that build them, rusticles offer a peek into the evolution of multicellular life itself.

Iron related bacteria (IRB) have been British-born Cullimore's passion ever since earlier research in the water wells of his adopted home, the land-locked Prairie provinces. He participated in the 1996 exploration of the Titanic, when it became apparent that the rusty concretions festooning the wreck were actually evidence of remarkably tenacious and unique life forms. The first dives and robotic flybys of the Titanic viewed rusticles as obstacles or nuisances, much like stalactites in caves. Now Cullimore and his colleague Lori Johnston will be aboard the 1998 Titanic expedition with a whole new bag of experiments up his sleeve.

Previous Titanic rusticles have been gleaned from steel brought up from the debris field that surrounds the wreck. But this year's grand plan is to successfully raise the "big piece": the stern section that was brought within a few metres of the surface in 1996 before stormy seas sent it to the bottom again, to rest ten kilometres from where it previously lay. "George Tulloch will not sleep until that piece is up," observes Cullimore, referring to the leader of the expedition and founder of RMS Titanic Inc, the company to which American courts awarded salvor-in-possession rights in 1994.

Rusticles come in a number of distinct shapes.
Cullimore will probably not sleep after the big piece is brought up - he estimates it will yield one to four tonnes of rusticles. The hull plates of both stern and bow sections literally drip iron sludge, as rusticles extract iron from the steel plating at a rate of .1 of a tonne per day - roughly a tonne every three years. The inanimate product of a group effort by more than twenty different types of bacteria and 2 types of fungi, the rust-hued structures possess a life of their own for Cullimore. "While the rusticle looks large and is complex it's not really a single species," he explains. "It's a group of species of microorganisms that are working together to create a common habitat." He calls that habitat "a living biological concrete", incorporating clay from the ocean floor, broken glass and coal from the ship's contents, small bits of gravel deposited by melting icebergs above, all enveloped by the Titanic's iron.



What is most intriguing about the rusticle, which ranges from a few centimetres in length to three metres across, is its uncanny resemblance to a living organism. Far from being a mass of indistinct rust, it has been formed by its inhabitants into a series of recognizable differentiable structures. There are internal water channels, hard iron-rich plates, porous sponge-like layers and ducts that connect inside water channels to the outside. Iron-rich water circulates through the rusticle, perhaps gravity driven, or perhaps driven by carbon dioxide generated by the microorganisms. "It has a primitive circulatory system. There's a lot of iron in it and it makes one think of the obvious comparison - blood," says Cullimore. "One of the strangest things is when you X-ray a rusticle you see a lot of puffy clouds which is where the iron is concentrated. And then you see little rivulets of concentrated iron, and it looks almost like a blood system."

The parallels between human and rusticle get closer to home as Cullimore points out the extent to which we can be considered consortial entities, just like rusticles. Most of us forget that we digest food and intake nutrients by the grace of independent microorganisms living in our gut, which we have to feed before we ourselves get to eat. And the very mitochondria found in every cell, the powerhouse organelles which provide us with energy, more resemble free living, self-replicating bacteria with their own separate DNA than they do part of our own body.