Using Citizen Science to Understand Thirty Years of Change in Global Kelp Cover by Expanding the Zooniverse to NASA Satellite Imagery
Jarrett Byrnes, University of Massachusetts, Boston
Macrocystis pyrifera or giant kelp is the world’s largest species of marine algae. The fast growing seaweed is found in dense shoreline stands where it provides food and habitat for a variety of marine animals, including snails, shrimp, crabs, sea urchins, abalone, fish, and sea otters. In these kelp forest environments, giant kelp is a foundation species playing a role similar to that of trees in land forests.
Kelp forests account for about a quarter of coastline habitats and are among the most diverse and productive nearshore environments. Kelp helps protect our shorelines from storm erosion and is a source of alginate, an ingredient used in products from shampoo to ice cream. Because giant kelp is important for the health, resilience, and productivity of our coastlines, scientists who study the shoreline want to understand how kelp forests are changing over time. Satellites can help.
Just like the forests on land, kelp forests can be seen from space. In fact, kelp forests were identified in some of NASA’s earliest satellite imagery. So, scientists hoped they could visualize change in kelp forests over time using Landsat imagery.
The Landsat series of satellites photograph the entire surface of the earth every 16 days, and have been doing so since 1984. Landsat imagery could provide an ideal way to measure long-term changes in kelp forests; however, Landsat was not designed to see kelp. Kelp’s reflectance signature (the wavelength of light kelp reflects) is just at the edge of Landsat’s detection abilities. Because of this, a computer has difficulty detecting differences between kelp and the sun glinting off of a wave. The shapes and patterns of kelp forests are fairly easy for a person to distinguish, however, so, a person can do a far more accurate job of identifying kelp than a computer.
Floating Forests is training citizen scientists to trace patches of kelp on Landsat imagery. So far, more than 20 years of imagery has been processed. The results are helping to uncover the history of giant kelp forests around the globe and the environmental factors that affect them.
Visit the Floating Forests at Zooniverse site for more information.
Last Updated: Jun 11, 2019 at 1:22 PM EDT