The lesser-known species

Certain endangered iconic animal species have captured the public imagination, such as the panda, polar bear, and tiger. But beyond this there are thousands of other species under threat from climate change, land-use changes, and pollution. In a study published in this month's issue, Ian Caldwell and colleagues find that conservation research is increasingly focused on the same suite of species and that targeted funding of understudied species is required. This editorial is about celebrating and highlighting some of the lesser-known species that are under threat. The UN International Day for Diversity in 2024 focuses on the interlinkages between freshwater and biodiversity, as freshwater ecosystems are currently under severe threat. Between 1970 to 2012, freshwater megafauna have declined globally by around 88% This decline can be attributed to a variety of factors. Climate extreme events such as drought and floods can have immediate and devastating impacts. Long-term changes in habitats such as the construction of man-made dams and water pollution caused by sewage, agriculture and industry all affect ecosystem health. Invasive species are also a growing issue in many parts of the world, where accidental introduction and/or climate change enables invasive species to thrive at the detriment of native species. The freshwater species we are highlighting is the fat threeridge mussel (Amblema neislerii), suggested to us by Ian Caldwell and colleagues. This particular freshwater mussel is found in Florida and Georgia and is on the IUCN red list as critically endangered. Like other freshwater mussels when they are larvae, they must find a fish to attach themselves to, acting as an ectoparasite until they are ready to detach. Therefore, impacts on fish populations can upset this delicate ecosystem balance. Once the larvae have metamorphosed, they burrow into the riverbed living a largely sedentary life. This location places them in danger from dredging of rivers. They are filter feeders transferring filtered materials and nutrients from the water column to sediments. And as such, sewage, fertilizers, and other chemical pollution all pose a threat. The last conservation assessment was 1996, meaning we have no accurate assessment of their numbers today. As with other freshwater species, many globally freshwater mussel species are declining at an alarming rate. The Glenelg freshwater mussel (Hyridella glenelgensis), Spengler's freshwater mussel (Pseudunio auricularius) and Unio foucauldianus are to name a few of the many species that are currently critically endangered. Furthermore, in a review by Aldridge et al., they highlight that there is limited available data on freshwater mussel populations in regions such as South America and Africa, which is urgently needed. Conversely, one particular species has been increasing in numbers. This is the Zebra mussel, (Dreissena polymorpha)—an invasive species that attaches itself to hard surfaces including other mussels, causing declines in native populations. Their fast reproduction and resulting large colonies can upset the balance of ecosystems by, for example, reducing phytoplankton and changing nutrient concentrations. They can also damage infrastructure such as water treatment facilities and power plants by clogging up pipes, potentially causing millions of dollars of damage. The freshwater mussel may not be quite as photogenic as the panda, polar bear, or tiger but is a vital component of our freshwater ecosystems. At Cell Reports Sustainability, we welcome submissions on the status, health, and conservation efforts of freshwater ecosystems and understudied species. Global trends and biases in biodiversity conservation researchCaldwell et al.Cell Reports SustainabilityMay 2, 2024In BriefConservation biology research seems biased toward popular species and ecosystems, with seemingly little attention paid to within-species (genetic) diversity. By looking through thousands of conservation-focused research articles, we found that these biases have been notably consistent over the last four decades. We saw that some of the most-studied species have low conservation risk, and some are domesticated animals. Animals and terrestrial ecosystems are consistently over-represented while plants, fungi, and freshwater ecosystems remain under-represented.