Three new peer-reviewed publications help to fill critical gaps in knowledge about Central America's freshwater ecosystems, which support extraordinary biodiversity but remain among the least-studied ecosystems in the world.
The publications document results from the most comprehensive freshwater mussel surveys ever conducted in Honduras and El Salvador, alongside the rediscovery of a fish species not recorded in one Honduran river system for nearly 80 years. These research papers were produced through collaborations between the International Union for the Conservation of Nature's Species Survival Commission (IUCN SSC) Center for Species Survival Freshwater (CSS Freshwater) hosted by Shedd Aquarium, members of the IUCN SSC Mollusc Specialist Group and other partners in Honduras and El Salvador.
"These kinds of surveys are the necessary first step before any meaningful conservation action can happen," said Dr. Yasmín Quintana, manager of IUCN SSC CSS Freshwater and co-author on all three studies. "We cannot protect aquatic biodiversity until we know what is actually living in each habitat, and what threats each species is facing."
Together, the studies demonstrate how sustained, boots-on-the-ground fieldwork paired with genetic analysis can rapidly transform scientific understanding of a region's aquatic life. Each paper and discovery informs conservation assessments and gives freshwater managers a foundation for protecting these waterways.
"Beyond these publications, this cross-country collaboration will have positive ripple effects on the future of conservation in Central America," said Dr. Jose Enrique Barraza, researcher at the El Salvador Ministry of Environment (MARN). "Support from Shedd led to the establishment of the National Freshwater Bivalve Conservation Program within MARN, which will continue to monitor and research local ecosystems in El Salvador, rescue and relocate vulnerable animals and expand environmental education in our communities."
HIDDEN FRESHWATER FILTERS IN HONDURAS
Freshwater mussels are long-lived filter feeders that clean water, cycle nutrients and stabilize sediment. Unfortunately, they are also among the most imperiled animals on Earth, with roughly 45% of species worldwide considered near threatened, threatened, or already extinct. In Central America, basic questions about which mussel species exist and where they are found have been largely unanswered for decades.
In Honduras, a team led by Dilenia Martínez of the Instituto de Investigación en Ciencias Biológicas y Ambientales de Honduras (IBIOAH) surveyed 32 sites across the country's rivers, lakes, and lagoons, confirming five mussel species , two of which are reported in the country for the first time. The team found that mussel distributions were patchy and diversity differed between the Caribbean and Pacific drainages. Genetic analysis also revealed a few unresolved taxonomic puzzles among populations, which will guide future research.
MUSSELS AND CLAMS ACROSS EL SALVADOR
A parallel effort in El Salvador, led by Dr. José Enrique Barraza of the Ministerio de Medio Ambiente y Recursos Naturales, surveyed 35 sites across 24 rivers, lakes and lagoons. This was the most extensive assessment of the country's freshwater mussel populations to date and confirmed two native species and one non-native species . The survey also documented the continued spread of the invasive Asian clam and confirmed an established, non-native population of a Pacific pond mussel. Genetic data also helped resolve a long-standing taxonomic question between two native species of freshwater mussel, giving scientists the tools to properly identify species in the future.
Together, the two studies give conservation planners in both countries a current, genetically verified picture of where native mussels persist, where invasive species are expanding and which populations may warrant closer protection.
AFTER 80 YEARS, A LITTLE FISH IS FOUND AGAIN
A third publication , led by Wilfredo Matamoros of the Universidad de Ciencias y Artes de Chiapas and IBIOAH, reports the rediscovery of the mountain mullet (Dajaus monticola) in the lower Choluteca River on Honduras's Pacific slope.
Although the species is common on the Atlantic side of the country, it had only been documented on the Pacific slope's Choluteca drainage once before from a single specimen in 1946. During fish surveys conducted alongside the mussel fieldwork in 2026, researchers discovered a juvenile mountain mullet, confirming the species persists in the river after an 80-year absence from the scientific record.
The mountain mullet is highly sensitive to dams and river fragmentation, so its rediscovery is both encouraging news and a reminder of how easily such populations can be overlooked and lost without ongoing monitoring.
FROM CHICAGO TO CENTRAL AMERICA
All three studies were made possible by fieldwork support and laboratory analyses provided by Shedd Aquarium's CSS Freshwater . Centers for Species Survival (CSS) are partnerships between the IUCN SSC Chair's Office and leading species conservation organizations. Work within Shedd's CSS Freshwater includes using applied conservation science to inform biodiversity assessments and safeguard freshwater species and ecosystems in crucial biodiversity hotspots in collaboration with the IUCN SSC Specialist Groups. The resulting datasets from these three publications provide the occurrence records, distribution maps and genetic baselines that IUCN Red List assessors and freshwater managers need to make informed conservation decisions in a region where such data has historically been scarce or outdated.
