Activity: Find a vent

Go to the Find a Vent interactive. Read the four parts of the overview, and as you do, complete the activity below. When you are done, go to "The Expedition" and see if you can find a vent. IntroductionA hydrothermal vent is formed when magma meets ocean water. The temperature of water and chemicals coming from them is very hot. Many have been found along mid-ocean ridges. These mountain ranges are formed where tectonic plates meet. The first hydrothermal vent was found in 1977 quite by chance by the Alvin during a sea exploration. It is not practical, however, to search for the vents themselves, but instead locate the plumes of warmer water that can be detected from the surface.Finding plumes Scientists use instruments called CTD - which stands for Conductivity – Temperature- Depth to find plumes. The instruments are towed behind the ship and collect water samples. Scientists can detect plumes because their chemistry and temperature is different from the surrounding seawater. However, they can be hard to detect because the fluid cools in the ocean so scientists must take continuous readings. To help their chances of detecting anomalies in the water, scientists tow the CTD in a “tow-yo” pattern, meaning they drag it in a zig zag pattern through the water. It is possible to detect plumes from several vents over the several kilometer tow.Finding ventsAfter a plume has been found, scientists launch the CTD down to the seafloor. This creates a vertical cross-section of the plume, which could be 200 meters thick and several kilometers long. The differences in temperature that could indicate a plume are very slight. Once a vent has been located, scientists launch a submersible or ROV to the seafloor to collect samples, images, and more data. The ExpeditionNow move on to the expedition, where you will use your knowledge of the techniques to locate a deep sea vent. Read the directions below carefully to help you navigate the interactive.Find a plume. Click in several places along the seafloor grid until you locate a temperature anomaly indicated by a color change in the temperature profile. Use the key at the bottom to help you.Plot a route. Once you find a potential plume, plot a route through that area where the anomaly was detected with your mouse. Remember that the ship has to take continuous measurements, so you want to move through the area several times (use the dots as a guide). Your route has to be 50 km in total length.Launch ship. As the ship moves along the route you selected, click “select reading” when you are ready to take readings along your route. Be ready to select “take reading” – the ship moves fast. You should probably take several readings, as anomalies can be small and hard to detect.Choose a line segment. Based on your initial temperature readings and where you took additional readings with the CTD (the last step), select one line segment (path) where you will release the CTD to create a tow-yo pattern through the water column.Drop probes. Move the arrows to select where you want to drop the CTD probes to the seafloor to get readings throughout the water column. Be sure to look for temperature anomalies.Drop submersible. Finally, move the ROV to a position where you noticed a temperature anomaly in the tow-yo and launch the ROV to further investigate the sea floor.Did you find a vent? Great! Take a screenshot of your success and upload it to the Canvas assignment page.Didn’t find a vent? Try again! Remember that this is a scaled down map – what seems like centimeters on your screen is actually kilometers in the ocean. 1. When you searched for a plume, what did you look for to determine where you would launch your ship? 2. Why don’t scientists look for hydrothermal vents directly? List two reasons. 3. If hydrothermal sea vents are commonly found near mid-ocean ridges, can you think of any other ways that scientists could narrow down their search using other methods? 4. There are dense communities that live along hydrothermal sea vents. What specific adaptations to these hot, sulfur-rich environments do you think those organisms might possess?