New Global Efforts to Map and Monitor Kelp Forests Extend to South Africa and Namibia

A new expansion of Kelpwatch.org brings more than 40 years of satellite-derived kelp canopy data to South Africa and Namibia, offering new insights into these vital underwater forest ecosystems.

One third of the world’s coastlines are home to vast underwater forests of kelp. These submerged forests sway with the currents, providing a critical habitat for abalone, West Coast rock lobster, leopard catsharks and other marine life while supporting fisheries, tourism and recreation, and they have deep cultural significance for different Indigenous communities around the world.

Until recently, our understanding of the health of these underwater forests has depended upon our ability to get out into the ocean to observe them directly, a process that—while incredibly valuable—is time-intensive, expensive and limits our ability to track kelp forests over larger scales. Now, with the development of a method that classifies kelp canopy on the ocean’s surface from satellite imagery, scientists at the Woods Hole Oceanographic Institution (WHOI) have brought us an entirely new view of these amazing ecosystems.

In 2020, The Nature Conservancy (TNC) partnered with Dr. Tom Bell and his team at WHOI to ensure that these essential kelp maps were easy to access and interpret by managers and practitioners alike. Together, the team developed Kelpwatch.org, a public tool used to quickly and easily map, monitor and explore seasonal and spatial changes in canopy-forming kelp ecosystems over the past 41 years. While the kelp maps on Kelpwatch.org originally only extended from Washington, USA to Baja California, Mexico, the team has worked with Dr. Tom Bell and Dr. Henry Houskeeper at WHOI to continue expanding this kelp mapping effort to other regions around the globe, including Peru and Argentina.

Today, TNC and WHOI are excited to announce the expansion of Kelpwatch.org’s mapping and monitoring tool to South Africa and Namibia—a region with some of the most extraordinary kelp forests on Earth. “The expansion of Kelpwatch.org to South Africa and Namibia is a monumental step forward in our global efforts to understand and protect kelp forests,” says Norah Eddy, associate director of the Oceans Program for The Nature Conservancy in California. “This dataset not only provides invaluable insights into the health and stability of these ecosystems, but also empowers researchers, conservationists and policymakers to make informed decisions. By extending our mapping capabilities to these regions, we are enhancing our ability to monitor and steward these vital underwater forests for future generations.”

This dataset captures South Africa and Namibia’s canopy-forming kelp species, Ecklonia maxima (sea bamboo), Macrocystis pyrifera (giant kelp) and Laminaria pallida (split-fan kelp). Kelpwatch.org provides seasonal kelp canopy maps at a 30-meter spatial resolution from 1984 to the present.

The maps create a continuous historical record that allows researchers and managers to track long-term patterns of kelp growth, loss and recovery. “Mapping the canopy-forming kelp forests of southern Africa is an exciting opportunity to better understand how environmental conditions influence these vital systems,” says WHOI’s Dr. Henry Houskeeper, a lead scientist for the project. “Testing kelp forest responses to changing water clarity, upwelling intensity and ocean circulation across the region will provide valuable insights into how kelp forests respond to shifting conditions.”

While many kelp forests worldwide face alarming declines, the team’s early analyses suggest that kelp ecosystems in South Africa and Namibia have remained remarkably stable over the past four decades. Future work with this dataset will allow scientists to examine finer-scale variations along latitudinal gradients and assess how ocean temperature fluctuations, seawater nutrient availability and land use changes have influenced kelp canopy distribution over time.

TNC’s Benguela program is working to protect the extraordinary kelp forests in this region through targeted efforts to improve management of South Africa's Agulhas Bank Complex marine protected area and provide scientific support for the declaration of additional marine protected areas in Namibia. Read more about this work on TNC's website.

The expansion was led by Dr. Henry Houskeeper and Dr. Tom Bell at WHOI, in partnership with TNC. It was made possible with funding from NASA and TNC. Maggie Reddy, AJ Smit, John Bolton and Chris Boothroyd generously provided feedback and expert input during the development and/or review period.

The research has been further strengthened by NASA’s Biodiversity Survey of the Cape (BioSCape) campaign, which deployed advanced airborne sensors to capture high-resolution imagery of kelp forests. BioSCape’s hyperspectral sensing data serve as a crucial benchmark for validating this Landsat-derived dataset, ensuring greater accuracy in mapping kelp canopy extent and detecting changes in kelp physiology.

Kelpwatch.org is an open access, interactive platform built to ensure the accessibility and utility of global kelp mapping efforts. Scientists, conservationists and policymakers can use this resource to analyze kelp canopy changes, compare trends between and within regions, and develop strategies for protecting these vital marine ecosystems.

Kelpwatch.org is a collaboration between TNC, WHOI, NASA, UC Santa Barbara and UC Los Angeles. The team is excited to continue expanding this tool around the globe and ensure it remains accessible to all.

About Woods Hole Oceanographic Institution

The Woods Hole Oceanographic Institution (WHOI) is a private, non-profit organization on Cape Cod, Massachusetts, dedicated to marine research, engineering and higher education. Established in 1930, its primary mission is to understand the ocean and its interaction with the Earth as a whole and to communicate an understanding of the ocean’s role in the changing global environment. WHOI’s pioneering discoveries stem from an ideal combination of science and engineering—one that has made it one of the most trusted and technically advanced leaders in basic and applied ocean research and exploration anywhere. WHOI is known for its multidisciplinary approach, superior ship operations and unparalleled deep-sea robotics capabilities. We play a leading role in ocean observation and operate the most extensive suite of data-gathering platforms in the world. Top scientists, engineers and students collaborate on more than 800 concurrent projects worldwide—both above and below the waves—pushing the boundaries of knowledge and possibility. For more information, please visit www.whoi.edu.