Sargassum Returns! Seeing Inundation Events with Earth Observations

Category: Assessing Air Quality and Water Resources
Project Team: Caribbean Oceans II
Team Location: NASA Ames Research Center – Moffett Field, California

The Floating Algal Index (FAI) applied to a Landsat 8 scene from 2015 shows Sargassum windrows caught in an eddy off the Cayman Islands. Image Credit: Caribbean Oceans II team

The Floating Algal Index (FAI) applied to a Landsat 8 scene from 2015 shows Sargassum windrows caught in an eddy off the Cayman Islands. Image Credit: Caribbean Oceans II team

Authors:
Jordan Ped
Emma Accorsi
Maria Lopez-Peña

Mentors/Advisors:
Dr. Juan Torres-Pérez (Bay Area Environmental Research Institute)
Sherry Palacios (Bay Area Environmental Research Institute)

Past/Other Contributors:
Erica Scaduto
Chippie Kislik (Center Lead)

Abstract:

In 2015, Caribbean nations were overwhelmed by an unprecedented quantity of Sargassum that washed ashore. This issue prompted international discussion to better understand the origin, distribution, and movement of Sargassum, a free-floating brown seaweed with ecological, environmental, and economic importance. In the open ocean, Sargassum mats serve a vital ecological function. However, when large quantities appear onshore without warning, Sargassum threatens local tourist industries and near-shore ecosystems. As part of the international response, this project investigated the proliferation of this seaweed using NASA Earth observations for detection of Sargassum and available nutrients across the region. The Caribbean Oceans team at the NASA Ames Research Center compared Landsat 8 Operational Land Imager (OLI) imagery to Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) across a number of indices for the identification of Sargassum. The Floating Algal Index (FAI) using Landsat 8 OLI imagery was used to effectively detect floating Sargassum mats and windrows. In response to limited ground truth data on Sargassum presence, the team assessed the accuracy of Instagram as tool for use during Sargassum inundation events, and found that Sargassum presence could be visually confirmed in 79 percent of Landsat scenes with corresponding Instagram hashtags. As part of the international effort to better understand the life cycle of Sargassum in the Caribbean, the results of this project will assist local economies and help promote sustainable management practices.

Previous story | Main Page | Next story

Tags: