“Emitting the pulse,” Krotine announced. Outside the viewport, Tuvok saw the city lights flare and go dark. Moments later, faint lights returned at a few key facilities with emergency power, including the hospital below.
“Take us down,” Tuvok said. “Can we get a transporter lock on any of our personnel?”
Krotine shook her cherry-tressed head. “No, sir. There’s a jamming field being generated by the heavy shuttle. We can’t beam in either.”
“Very well. Douse all external lights and bring us in as stealthily as possible. We shall make our way on foot.”
TITAN
“The situation is worse than we thought,” Melora told Vale and the others in the observation lounge.
“Naturally,” Vale said. “Because things have just been going sowell this week.”
Melora waited, but rather than saying more, Vale nodded, signaling her to continue. “It turns out the barophilic life Cethente discovered in the saltwater dynamo layer has more influence on the life up above than we initially thought,” the science officer went on. “In two ways. First, it turns out that a lot of the subtle patterns we read in the dynamo layer’s field were actually generated by the barophiles’ communication. It’s the disruption to the barophiles’ life cycle, caused by the exotic radiation in the infalling asteroid dust, that’s altering the planetary magnetic field, and that’s what’s stirring up the surface life.” It was odd to start referring to the oceangoing life of this planet, even that living in the deeps kilometers down, as “surface life.” But a world like this forced one to redefine one’s parameters.
“Symbiosis,” Keru observed with a touch of Trill irony. “The life up above is feeling the pain of the life below.”
“You’re more right than you know, Ranul. There’s a deeper symbiosis as well.” She moved to the wall screen and called up an image of several tiny arthropod forms, magnified thousands of times. “These are bathyplankton—the deep-sea zooplankton that Cethente sampled in the intermediate layers of the ocean, even deeper than we’d sampled them before. As you’ll recall, we were wondering why they would exist at such depths when there’s no sunlight or food to sustain them. Well, Eviku and Chamish figured that out.”
She altered the display to show the creatures alternating between two modes. “It turns out the bathyplankton have a dual biochemistry. Their life functions are based on two distinct types of organic molecules. One is the ordinary type found in the surface life and most carbon-based life forms. The other is the type found in the barophiles. At low pressures, normal life processes operate and the barophile molecules are inert, just part of their structural bracing, which is why we didn’t register the bathyplankton’s dual life cycle before. Near the surface, they consume organic nutrients and use photosynthesis to store solar energy—making them as much phytoplankton as zooplankton.
“But eventually, if they don’t get eaten, gravity and convection currents pull them into the depths. As they sink further, their normal enzymes stop working, and they fall dormant. But then, when they get down to the dynamo layer, the pressure and temperature become great enough for their barophile biochemistry to become active.”
“But how do they stand the pressure down there?” Ra-Havreii asked.
It was practically the first thing he’d said to her since the shuttle. Fortunately, Melora didn’t have to respond directly to him. She called up a cross-section graphic, pointing to an array of small, glassy spindle shapes within them, and addressed the group. “They have an internal skeleton of silicate spicules. Up top, the spicules are loosely distributed, giving them some additional structural strength but leaving them fairly flexible. As they descend, they’re compressed further and further, the spicules coming together into a tight, geometric array that braces them against the pressure. As with the pure barophiles, the silicate framework contains and directs their molecular machinery the way cell walls do in our kind of life.”
“That’s fascinating, Commander,” Vale said, “but how does it connect the barophiles to the surface life?”
“Sorry,” Melora said. It was easy to get caught up in the wonder of this. “The critical thing is what the bathyplankton do once they’re down there. They feed on the metals and heavy elements that are part of the saline layer’s biosphere, the residue given off by the barophiles.”
“Which they in turn consumed from the clathrates in the mantle,” Onnta said.
“Exactly. And once they’ve stockpiled on metals, they swim upward until they reach the interface with the normal ocean. Then they spread fins that let them catch convection currents that carry them back up to the surface. The barophile life functions fall dormant, they drift upward, and finally their normal life functions engage again.”
Vale’s eyes widened. “And once they’re up there, being plankton, most of them end up getting eaten by bigger critters.”
Melora nodded. “Except enough of them survive to reproduce and start the cycle over again.”
“But they’re how the metals get back up from the mantle to the upper ocean. They’re what makes it possible for life to exist on the surface.”
The Elaysian couldn’t help grinning, despite the gravity of the situation. “An entire biosphere, a whole sentient civilization—it wouldn’t exist without these tiny, invisible creatures. Chamish suspects the barophile biosphere evolved first, driven by the energy of the magnetic dynamo, and that these bathyplankton somehow developed the ability to spread up to the ocean surface and take advantage of a new energy source, sunlight. Maybe they initially relied on some kind of organic molecules that could function well at intermediate pressures and marginally at surface pressures, and eventually replaced them with molecules better suited to surface life. Finally some of them evolved into forms that lived permanently on the surface and lost their extraneous barophile compounds, and the rest of the surface biosphere evolved from those.”
“But what matters,” Vale said, “is that the surface life depends on the barophile life for its survival.”
“Yes, ma’am.”
“And the barophile life is dying.”