Dataset 4: Animal Distribution with Temperature
Hello FLEXE Forum fans. My name is Chuck Fisher. I'm a deep-sea biologist. My colleagues, students and I study the animal communities found at places like the hot hydrothermal vents along the East Pacific Rise and at cold, hydrocarbon seeps found in the Gulf of Mexico. These animal communities are some of the most interesting in the world because they are so unique. And traveling to these places, using submersibles like Alvin and the ROV Jason, makes our work all the more challenging and fun.
As you've learned already, the vent environment is characterized by extreme conditions (e.g., super hot fluid, near-freezing seawater, pitch darkness, crushing pressure). In spite of these conditions, however, hundreds of different species of animals live there. In most ways, these communities of animals are similar to others found throughout the oceans - with one notable exception. In surface water ecosystems, plants (or phytoplankton) are at the base of the food web. But in the deep-sea ecosystem, the foundation is microbial. Remember, sunlight can not penetrate these ocean depths so plants do not exist at vent sites. Instead, microbes (bacteria and archaea) harness energy from vent fluid to convert CO2 to sugars - a process known as chemosynthesis. The product of this process then fuels the rest of the animals.
Chemosynthetic microbes are found nearly everywhere in this deep-sea hydrothermal vent environment. They are found growing on rocks, under the ocean floor, in mats stretching over seafloor rocks and sessile animals, and even inside animals. I'm interested in studying the animals that acquire the bulk of their nutrition from these microbes. Animals like tubeworms, mussels and clams, live in a symbiotic relationship with bacteria. Here's how it works. The animal (e.g., tubeworm) absorbs or takes up hydrogen sulfide, oxygen, and carbon dioxide from the environment using its plume, and provides these raw materials to bacteria living inside them - that's right - inside them. The bacteria, in exchange, use the raw materials to create sugars that are shared with the animal.
Two other fascinating animals found at hydrothermal vents are mussels and clams. The deep-sea mussel, Bathymodiolus thermophilus, is found in clusters around cracks in the seafloor. The mussel has symbiotic bacteria living in its gill tissue and lives off of the simple carbohydrates produced by the bacteria. The mussel can also filter feed allowing it to survive for short periods when hydrothermal fluid stops flowing. The other bivalve is the giant white-shelled clam, Calyptogena magnifica. Like mussels, the clam lives off the nutrients produced by bacteria living inside it. However, to obtain sulfides for its symbionts, the clam actually uses its foot! It thrusts its foot down into cracks of the basalt rock to reach deep pools of sulfides. On the other end, it uses its siphon to bring in seawater rich in O2 and CO2.
Since the discovery of vent communities in the late 1970's, marine biologists have collected and studied over 600 new species. You can learn more from the following websites: The American Museum of Natural History Web site on hydrothermal vent life forms and the Dive and Discover Web site on vent biology.
Data Collection
Studying living organisms in the remote environment of the deep-sea presents many challenges - but that's also what makes it so fun. One of the most important tools we use in the deep-sea is the camera. Photographic images allow us to capture a 2D snapshot or 'sample' of the animals living around a vent. Images allow us to quantify the number of organisms in particular areas (only an estimate though since you can't really see how many are piled on top of each other). We can also study their distribution (i.e., where are the animals found, what other animals are there too, how many are living there). Combining photographic images with other data, such as temperature measurements, can greatly enhance our understanding of the organisms living there.
This last dataset consists of two parts: part one is a high-resolution photographic image of a section of the seafloor and part two is a set of temperature measurements made along the same section of seafloor. These data are actually part of a much larger study to understand the ecology of hydrothermal vent organisms, conducted by my lab over several years. This photograph was taken by a high-definition camera attached to the bottom of the submersible Alvin. The image is in the vicinity of the Bio9 chimney along the East Pacific Rise in an area where there are cracks in the seafloor. The cracks vent warm (5-10°C) chemical-rich fluid - called "diffuse flow" rather than the "focused flow" vents characteristic of the black smoker chimneys.
Shortly after this image and many others were taken, we took temperature readings at several locations around the area. We wanted to know if there is a correlation between temperature and where the animals are found. Due to time limitations with the sub, we were only able to get 18 readings in this area before having to resurface.
Your job is to see if you can discern patterns in the distribution of animals, and to see if there is any correlation with the temperature data. Use the grid lines to plot the temperature readings over top the image, then look for patterns. The questions in the handout will guide you. When you are ready, go to the next page to enter your responses. We look forward to seeing what you find in this unique dataset!
Alvin submersible starting its descent
Jason II, the remotely operated vehicle (ROV), being launched
The following images are courtesy of R. Lutz, Rutgers University, Stephen Low Productions, and Woods Hole Oceanographic Institution:
Tubeworms (Riftia pachyptila) with vent fish and crabs
Mussels (Bathymodiolus thermophilus) with crabs, squat lobster and tubeworms
Clams (Calyptogena magnifica) in crack in basalt rock, with shrimp (reddish colored)
Deep sea octopus
Squat Lobster (Munidopsis subsquamosa)
For more information on vent organisms, visit the following links: