Life in Extreme Environments: A Study of the Prevalence of life in the Depths of an Underwater Rift Zone

Mid-Ocean Ridge Center of tectonic activity located towards the middle of an ocean. Source of seafloor spreading. New land is created at all Mid-Ocean ridges which then spreads outwards towards deep ocean trenches. Contains a rift zone which appears as valleys running along its spine. The rift zone is booming with biological activity, as a result of the areas hydrothermal vents. Depicted in the diagram to the right is the East Pacific Rise, a mid-ocean ridge located in the Pacific ocean, which will be the basis of our study.

Hydrothermal Vents in the Rift Zone Form where there is underwater volcanic activity – primarily in rift zones. Caused by the infiltration of seawater into the crust where it is heated and shot back into the ocean via the chimney of the vent. In the crust, the temperature of the water is raised up to 400°C. Additionally, the water is deoxygenated, made acidic, gains hydrogen sulfide, and picks up a variety of dissolved metals including iron, copper, and zinc. The heat at these vents make them ideal spots for biological activity.

Vent Life Typical vent lifeforms include tubeworms, octopi, clams, shrimp mussels, zoarcid fish, crabs, and various microbes. As sunlight does not reach the floor of the rift zone, the main sources of energy for the system are the vents. The sheer amount of chemicals emitting from these vents allow a series of microbial chemosynthetic reactions to take place which provides the basis of all of the energy in the food web of the system.

Topographic Profiles of the East Pacific Rise Shown below is the partial profile of the topography of the East Pacific Rise.

Topographic Profiles of the East Pacific Rise (continued) Shown below is a cross section of the East Pacific Rise's topography. The vents and the majority of life forms are located in the trough in the middle of the profile.

Hypothesis 1 Life forms are only found inside the axial trough of the East Pacific Rise. We will test this hypothesis by analyzing a series of maps using the program GeoMapApp.

Life in the East Pacific Rise

Blue dots represent hydrothermal vents with no presence of life. White dots indicate the presence of life. Based on the previous image, it is clear that life exists both inside and outside the trough.

Hypothesis 2 Water temperature plays in important role in determining where certain species are found on the east pacific rise. We will test this hypothesis by using the program GeoMapApp which will allow us to directly observe the relationship between temperature and number of life forms in specific regions.

Data Table

Hypothesis 3 Previously, we have determined that life exists both inside and outside of troughs. We have also established that water temperature does indeed affect the prevalence of life. As a new hypothesis we would like to establish a relationship between location, temperature, and prevalence of life.

Based on the graph, it is clear that water temperatures inside the trough is more suited to sustaining life. Another factor that influences temperature is whether or not hydrothermal vents are located within proximity, causing temperatures to spike. Finally, because temperatures inside the trough are more suitable for sustaining life, there is a greater prevalence of life inside of the trough.

Interpretation of Data In areas of both relatively low temperature, and relatively high temperature, there are not very many life forms, nor is there significant biodiversity. There is both biodiversity and many life forms in areas of temperatures ranging from 17°C – 22°C.

Conclusion Water temperature does in fact play a large part in detirmining how many life forms live in a specific region of the East Pacific Rise's rift zone. The ideal temperature for life forms seems to be anywhere from 17°C – 22°C. Areas in which the temperature is higher or lower house fewer organisms. Not only is the amount of organisms greater in this range of temperatures, but the biodiversity is greater as well.

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