Expedition 13 Mail Buoy

Dear Charles:

Our batteries are lead-acid batteries—just like the ones in a car, but much bigger. We have two 60-cell batteries that weigh a total of about 2,000 lbs and that we can jettison if we ever needed to in an emergency. They put out 120 volts of DC power. After every series of dives we take them out and recharge them.

—Dave Walter, Alvin pilot

The following questions are from Ms. Sheild's 7th grade science class, Clarke Middle School, Lexington, MA

Dear Omer:

We don't know if the oil is causing animals to migrate, but we do know it has killed some migratory animals (sea turtles). The bigger question is whether the oil is affecting the migration of larva and other zooplankton that move between the deep and shallow water daily. Their diurnal migration is an important part of the marine food web. If a layer of oil or chemicals is preventing them from moving through the water column, it could be bad for animals that rely on these organisms for food.

Dear Becca:

If we had gone down in the Gulf right after or during the spill, then yes—especially because of the solvents mixed in with the oil. We'd be worried about those damaging Alvin's hoses. But now it's OK. We dive where there's oil in the water all the time—particularly naturally occurring oil. Still, we considered the risks presented by oil in the Gulf and decided it would be safe.


I've had over 130 dives to the deep ocean, and we find something new on almost every dive. It just points to how poorly we know the deep sea. My favorite animals are the octopi—especially the "dumbo" octopus. I don't study them, I just think they're very cool.

Dear Allyson:

Any oil that comes out of the seafloor at a seep site would rise very quickly to the surface and wouldn't necessarily pool there, so we don't see that limiting species at seeps. Instead, we generally see depth determining which fish can survive there and, in fact, we see many of the same fish at seep and non-seep sites of the same depth. However, some species of fish and other animals have adapted to the low oxygen often found at seeps with specialized gill structures. In addition, there are species that have adapted to the chemical conditions at seeps with internal biochemical mechanisms to help them process sulfides and other chemicals dissolved in the water.

(A note from Ken: I'm sitting next to Andrea on the cruise and your question has caused her to think about new avenues of research in her PhD project!)

Dear Anna:

That's a complicated question. When tubeworms or mussels act symbiotically to convert inorganic carbon to organic carbon, we call the entire organism a "functional autotroph." (An autotroph is an organism that is a primary producer.) We don't think that the bacteria could survive in the wild as well or in the numbers we see in the host organism, and certainly the host could not survive without the bacteria, so we say that the ecological role of both together is primary production.

—Erik Cortes, Temple University