Putting a clear picture together

Desktop Investigation of Eelgrass Using PlanetScope Imagery

In 2016, the Cree Nation Government and Hydro-Québec launched a research programme on eelgrass (Zostera marina) off the east coast of James Bay, Quebec. The goal? Identify the various factors influencing eelgrass growth. Eelgrass provides many important ecosystem functions—from shelter and food to spawning surfaces for marine species. Indigenous knowledge from trappers in the area suggested that changes in the amount of eelgrass has resulted in less waterfowl.

Our contribution? A research project via the University of New Hampshire to investigate the usefulness of satellite imagery to map the extent of eelgrass beds along 260 kilometres of the south coast of James Bay in the Canadian Arctic. Our remote sensing experts used PlanetScope satellite imagery (producing tiles approximately 7 kilometres by 25 kilometres) to create a mosaic that covers the entire study area. With that mosaic—and 261 in-situ field points provided by the client—we were able to build an algorithm to automatically classify the imagery and identify eelgrass. Providing an overall accuracy of 73.7%, the process was much more practical than a field programme, which translated into cost savings for our client. 

Although water turbidity and high suspended sediment levels did pose technical issues in some locations within the study area, the project proved useful for the large-scale detection of eelgrass. With this research and the University of New Hampshire’s services, the Cree Nation Government and Hydro-Quebec will be better able to infer the factors (environmental or human-related) that relate to changes in eelgrass.