Updates From Sea | Cruise 2007
January 29th
By Eric Simms, Education Outreach Coordinator
Patterns - Do you see what I see?
Deep-sea crab.
Photo © DSV Alvin
Making observations of our world is a large part of what scientists do when they conduct research. Observations may include watching animals interact with each other, noticing what happens when conditions change as part of an experiment, or looking at data that is collected in the field or in the laboratory. Observing something once or a few times can provide valuable information - but when the same observation occurs repeatedly, or when we start to see a pattern, that's when things get interesting. And it's these patterns that lead us to pose questions.
Patterns are everywhere. We see them all time and actually use them to process information and come to conclusions. For example, recently I've noticed that the salad at each meal on the ship has included less lettuce and more green cabbage each day. The first time it happened, I simply wondered if it was just a change in the menu. But when it happened repeatedly, it caught my attention as a pattern, and I began to wonder what was causing it. Can you think of any ideas why more cabbage and less lettuce have been showing up in the salad bar? (keep reading to find out...)
Patches of white against the dark lava indicate seafloor life. Photo © DSV Alvin
Scientists are always looking for patterns to help understand the natural world, including the deep sea. On this cruise, we're making observations of the newly formed seafloor to understand how organisms colonize the new habitat. One of the first patterns scientists have noticed is that patches of white (easily seen against the dark lava background) often indicate that a new vent is near. Why? Because many of the bacteria, crabs, tubeworms, and fish found at vent sites are white or light colored, and these organisms need chemicals from the hydrothermal vent fluids for their energy. So if we see a lot of animals in one place, we know to check the water temperature and chemistry in the area for vents. Not only has observing this pattern helped us to understand that many organisms need to live close to the vents to survive, but it also makes us more effective at finding vents while in the Alvin submersible, and from other photos and videos.
Better check the water chemistry. There could be a vent here. Photo © DSV Alvin
Making observations and noticing patterns are really only the beginning. The fun part is that they lead us to ask questions. For example, some of the questions researchers are asking on this cruise include: Are worms from different vent sites the same type of worm? Does the water temperature differ between different sites? And what about the water chemistry - does the amount of sulfur and other chemicals change between sites, and how does that relate to the water temperature and organisms? Answers to these questions require looking closely at the data we collect for patterns over time.
Observing patterns not only leads to questions, but also to hypotheses. One interesting pattern that is emerging from this cruise has led to a hypothesis about the relationship between tides and the amount of fluids that emerge from the hydrothermal vents. Most people only picture tides as happening along the coastline - but the pull of the sun and moon also influence the level of water here in the open ocean. Apparently, when the tide increases the level of the water over the vent areas, the extra weight of the water creates more pressure against the seafloor. This extra pressure slows down the flow of fluids that come up through the seafloor and out of the vents. When the tide changes and the water level decreases, there is less pressure on the seafloor and more fluids flow from the vents. Scientists recognized this interesting pattern after looking at many measurements of the water pressure and water chemistry at vent sites, and noticing an interesting connection.
Are those tubeworms growing at the top of this lava pillar?
Photo © DSV Alvin
Oh yeah, I almost forgot to answer why more cabbage is appearing in the salad every day here at sea. Well, lettuce doesn't stay fresh for more than about two weeks, but cabbage can last much longer without spoiling. As we run out of fresh lettuce on the ship, it is gradually replaced with cabbage. And without looking at a calendar, we can use this pattern to tell us that it's been almost three weeks since we left port!
