Amazon Megafish Migration Project & International Sawfish Day
October 17, 2020

The Amazon region, both within the Amazon River and along coast north and south of the river, is home to numerous large, migratory fishes. One of these fishes, the largetooth sawfish, has been the recent focus of the EcoWB Amazon Megafish Migration project. And, with International Sawfish Day on October 17 th , and World Fish Migration Day on October 24 th , now is the perfect time to highlight the work being done by the Megafish team.  

Largetooth sawfish are a critically endangered species worldwide, listed on the IUCN Redlist of Threatened Species. They are also fascinating, both because of their unique body plan and because they are somewhat of a scientific mystery. Sawfish are a type of ray, though their body shape, with prominent dorsal fins and tail fins, means they are often mistaken for sharks. Their rostrum bordered by sharp rostral teeth is a unique adaptation that they use to both sense and hunt prey.  

From left: Dr. Patricia Charvet, Dr. Jens Hegg, Mariana Moro in Curitiba, Brazil holding sawfish rostrum samples from the Amazon region.

Largetooth sawfish are a euryhaline species, able to tolerate a range of salinities. They are sometimes known as Freshwater Sawfish because they are often found in rivers as well as in brackish environments. However, most of the current data on largetooth sawfish comes from Australia where their numbers are still somewhat plentiful. The Amazon region is thought to be one of the last refuges for the species in the Americas, but we know very little about their numbers or their behavior and ecology in this part of the world.  

The EcoWB team is working to better understand largetooth sawfish in the Amazon region using chemistry. Partnering with researchers in Brazil including Dr. Patricia Charvet, Dr. Tommaso Giarrizzo, and Dr. Jorge Nunes, Dr. Jens Hegg has identified and collected over 100 sawfish rostral teeth. Because the teeth grow throughout the life of the fish we have discovered that they record chemistry, particularly chemical records of salinity, which might allow us to better understand their distribution and behavior. The preliminary findings are currently in review and a pre-print of this work can be found on BioRxive.  

Study area used to create the GIS model.

The Megafish team has been hard at work this year collaborating with the EcoWB GIS Program to support this work. In order to reconstruct the chemistry within our sawfish samples it is important to understand the spatial variation of chemistry across the area being studied. This helps to narrow down the likely locations where sawfish may have travelled throughout their life, and better understand how these movements across fresh and brackish water relate to other important parts of their life-history. All of this, eventually, can help us understand more about the behavior and distribution of largetooth sawfish in the Amazon river and along the Brazilian Amazon coast.  

To this end the EcoWB GIS Program has helped to identify temperature, depth, and salinity datasets which can be used to characterize the potential habitats of largetooth sawfish in the Amazon region. In the coming months the team will be building these datasets into a GIS model that can be used to inform the chemistry we find in the sawfish rostral tooth samples we are working to import and analyze.

From left: Dr. Tommaso Giarrizzo, Dr. Jens Hegg, PhD Student Leonardo Feitosa, Dr. Jorge Nunes collecting donated rostral tooth samples near São Luis, Brazil.

 

Managing the Mangroves of Jiquilisco Bay: Science, Collaboration, and Community

November 5, 2025
Since 2023 EcoWB has been contributing its technical expertise to a multi-phase restoration initiative led by Asociación Mangle and the Mangrove Action Project in El Salvador’s Jiquilisco Bay, one of Central America’s largest and most diverse mangrove ecosystems. Together, these organizations and our technical collaborators aim to conserve, restore, and sustainably manage this globally significant ecosystem that supports biodiversity and local livelihoods. Its mangroves are globally important in sequestering carbon to mitigate the effects of climate change. Jiquilisco Bay, located on the Pacific coast of southeastern El Salvador, is a place of exceptional natural richness and ecological importance. Recognized as both a UNESCO Biosphere Reserve and a Ramsar Wetland of International Importance, it is home to one of Central America’s largest and most diverse mangrove forests, covering more than 20,000 hectares. These mangroves form the heart of the Jiquilisco Bay Biosphere Reserve, which spans around 400 km². It includes a mosaic of bays, channels, sandy beaches, islands, freshwater lagoons, and coastal forests. The reserve stretches along 50 kilometers of coastline between the Lempa River and the Jucuarán mountain range. The mangroves of Jiquilisco Bay—dominated by red, black, white, and buttonwood mangrove species—play a vital role in keeping the coast alive and protected. They reduce erosion, lessen storm impacts, and filter pollutants, acting as natural shields for coastal communities. Beneath their tangled roots, they are habitat for an astonishing variety of life, including fish, crabs, and sea turtles, such as the hawksbill, green, olive ridley, and leatherback, which are at risk of extinction. Above the water line they are vital for birds and other terrestrial animals. Beyond their ecological value, these mangroves are deeply connected to local communities, supporting fisheries, providing food and materials, and sustaining livelihoods. The project’s first phase focused on understanding trends in mangrove distribution and some of the factors influencing their health. Using Landsat satellite data and advanced machine learning techniques, EcoWB helped develop high-resolution maps of mangrove cover spanning three decades. This analysis identified key influences on mangrove viability, such as proximity to agriculture, urban expansion, elevation, soil conditions, and temperature. Building on that foundation, EcoWB supported a detailed assessment of mangrove cover changes and corresponding health and analysis of canopy height and aboveground biomass during a ten-year period (2016–2025) using Sentinel satellite and LiDAR data. The height and biomass (plant material) can be related to health, age, species composition, and site characteristics. The study underscored the need for continued protection, hydrological restoration, and community stewardship to strengthen ecosystem resilience. EcoWB is now helping translate that information into action through the creation of an open-source, interactive web platform. This tool will enable Asociación Mangle, the Mangrove Action Project, NGOs, government agencies, and local communities to visualize mangrove health trends and help identify priority conservation and restoration areas. Through knowledge transfer, EcoWB and its partners aim to empower local communities to make informed, science-based decisions for the long-term management of Jiquilisco Bay. This initiative demonstrates how collaboration, innovation, and community leadership can come together to safeguard one of Central America’s most vital coastal ecosystems. By combining cutting-edge science with local knowledge, EcoWB and its partners are helping ensure that Jiquilisco Bay’s mangroves—and the communities that depend on them—continue to thrive for generations to come. 

Supporting Those in Need During Uncertain Times

By Becky Muston • June 4, 2025
As a volunteer-supported ecological assistance organization, EcoWB contributes to the vital work of the international aid community—supporting humanitarian and conservation efforts where ecological expertise can make a meaningful difference. In recent months, critical funding and staffing for international aid once provided through U.S. government programs have been withdrawn. The effects are already visible: environmental and humanitarian programs paused, local teams let go, and progress at risk of stalling. Among the efforts most affected are those tackling biodiversity loss, habitat degradation, water pollution, and climate change—areas where EcoWB has long provided professional expertise and hands-on project support. In response, we’re actively looking for opportunities to support projects that need ecological guidance or technical capacity to keep going. With our global network of skilled volunteers, we’re well placed to step in where others no longer can. If you know of places, partners, or organizations where environmental needs are going unmet—or if you're looking to make a meaningful impact— we’d love to hear from you . We also encourage those with the means to do so to take a moment: research the organizations struggling on the frontlines, see where funding may have been cut, and consider offering your support. Now more than ever, action matters—whether it’s donating, volunteering, or simply amplifying the work that still needs doing.