Teacher's Report
Bill Hanshumaker, Educator at Sea

Dr. Ray Lee stand beside his experimental apparatus, which he designed for simulating the deep sea environment. He uses the apparatus to study how hydrothermal animals respond to stress.

Researcher Interview:
Ray Lee
Assistant Professor
School of Biological Sciences
Washington State University at Pullman

Bill:
Tell me something about the research that you are conducting here on the Thompson.

Ray:
Physiology is the science dealing with the functions and vital processes of living organisms. I'm an environmental physiologist interested in how animals respond to stress. Hydrothermal vents are perfect sites for studying stress because they are potentially toxic, high-temperature environments with rapid fluctuations. What we see at the vents is a gradation of different microenvironments with different intensities and different species of animals living there. For example, the sulfide worm is found in the hottest environment. Is this because the sulfide worm has higher tolerance to heat, or because it is being excluded from other areas due to biological competition?

Bill:
Can you tell us something about your experimental apparatus?

Sulfide worms, palm worms, juvenile tubeworms, and scale worms with bacteria on their scales all live upon a mass of limpets, mucus and bacteria. (Click for full-size).

Ray:
On this cruise we are using two different types of setups. One is for behavioral studies. We put animals into a thermal gradient under pressure, because you can't get valid experiments unless the animals are studied under their normal living conditions. In this case it is high pressure, over 2000 pounds per square inch! So we put them in specially designed chambers and vary the temperature. The other setup involves physiological measurements of respiration. We put the animals in pressure chambers under different temperatures and see how it affects their physiology. Generally, in nature when you increase the temperature, the animal's metabolism increases. Usually this means that the animal would need more food. So one question is: Do animals that are normally found in hotter environments exhibit lower effects of temperature? Do you see less of an increase in rates of metabolism compared to animals found in cooler environments?

Bill:
How are you measuring these changes in metabolism?

Ray:
Metabolic rates are correlated to oxygen consumption. The higher the metabolism the more oxygen that is consumed. I determine this by measuring the oxygen level of the water before and after it flows into the pressure chambers with the animals. We have automated analysis equipment that can measure that.

Bill:
Can you tell us something about the animals that you are using in this study?

Ray:
Mostly what I'm focusing on are the high-temperature animals that live in different thermal regimes. There's the sulfide worm, Paralvinella sulfincola that seems prefers extremely hot water, and the palm worm, Paravinella palmiformis that seems to prefer cooler water.

Bill:
What is the temperature range?

Ray:
That's controversial. Some observations have suggested that they can live in 60-degree Celsius (C) (140 F) temperatures, with spikes up to 80°C (176° F). But this is contradictory to the biochemical evidence that suggests the enzymes and proteins of the animal are not functional at that extreme temperature. The only way to really know what the animal can tolerate is to study them under known conditions. Last year I showed that they die at about 50° C (122° F). I think that 50 degrees is their thermal limit, and that they prefer temperatures under 45° C (113° F).

Bill:
What ramifications do you see for the results of your research?

Ray:
On a smaller scale, there have been ecological studies of vent communities without a sense of the physiological aspects. For example: animal recruitment, distribution or species succession could be due to biotic factors such as competition or food availability; or it could be due to abiotic factors like water chemistry or temperature. Understanding the impact of the abiotic components is one thing that can be addressed by physiological studies. On a broader scale, these vent animals are unlike the typical laboratory animals such as the white rat. If we only study animals that we can maintain in the lab, then we are biasing our whole understanding of physiology. For example, we can use the rat model to infer the biology of a deep-sea organism, but can't necessary know that. We are developing the technology to study animals that live under extreme environments. Fundamental biology, like how hemoglobin works, is based on laboratory animals such as rats. But rats are highly evolved and specialized animals, and don't necessarily represent what happened in early earth history. Earth's initial atmosphere didn't contain oxygen. The sulfide worm is more representative of the type of animals that have been on earth much longer than rats. Tubeworm hemoglobin also binds hydrogen sulfide, which was present in the early earth's atmosphere. Hemoglobin predates oxygen, so if you what to study how hemoglobin evolved, using animals such as the sulfide worm may provide interesting insights. Knowing why essential molecules such as hemoglobin work the way they do, can be more important than just understanding how they work.