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The atypical arrival of pelagic Sargassum to the Mexican Caribbean beaches has caused considerable economic and ecological damage. Furthermore, it has raised new challenges for monitoring the coastlines. Historically, satellite remote-sensing has been used for Sargassum monitoring in the ocean; nonetheless, limitations in the temporal and spatial resolution of available satellite platforms do not allow for near real-time monitoring of this macro-algae on beaches. This study proposes an innovative approach for monitoring Sargassum on beaches using Crowdsourcing for imagery collection, deep learning for automatic classification, and geographic information systems for visualizing the results. We have coined this collaborative process “Collective View”. It offers a geotagged dataset of images illustrating the presence or absence of Sargassum on beaches located along the northern and eastern regions in the Yucatan Peninsula, in Mexico. This new dataset is the largest of its kind in surrounding areas. As part of the design process for Collective View, three convolutional neural networks (LeNet-5, AlexNet and VGG16) were modified and retrained to classify images, according to the presence or absence of Sargassum. Findings from this study revealed that AlexNet demonstrated the best performance, achieving a maximum recall of 94%. These results are good considering that the training was carried out using a relatively small set of unbalanced images. Finally, this study provides a first approach to mapping the Sargassum distribution along the beaches using the classified geotagged images and offers novel insight into how we can accurately map the arrival of algal blooms along the coastline.

In recent years, the unusual arrival of Sargassum to the coasts of the Caribbean Sea has caused considerable damage, both economic and ecological. The monitoring of this macroalgae is a major challenge for researchers. Historically, satellite remote-sensing has been used for this purpose; however, limitations in the temporal and spatial resolution of available satellite platforms do not allow for the monitoring of Sargassum on beach coastlines. The increase in the capacity of communication and the decrease in the costs of technology have enhanced users’ access to intelligent mobile devices. Crowdsourcing has proven to be successful in combining informational technology with a collaborative solution to complex problems. This study demonstrates how crowdsourcing and the new technologies, can be used to monitor Sargassum on the beaches in Quintana Roo, complementing satellite monitoring.