Africa's tropical belt, defined by the Guinean forests of west Africa and the Congo Basin of central Africa, is globally recognised for its astounding biodiversity.
Beneath the surface of this ecological region lies the world of freshwater macroinvertebrates. These are tiny creatures inhabiting rivers, streams and lakes. In the words of renowned American ecologist Edward O. Wilson: invertebrates are the little things that run the world.
Macroinvertebrates include snails and larvae of dragonflies, caddisflies, mayflies and stoneflies, among others. They can be described as ecological engineers of freshwater ecosystems. They break down organic material, recycle nutrients, and form the base of food webs.
More importantly, they are the best biological indicators of freshwater ecosystem health. Their presence or absence tells the story of pollution, habitat degradation, or environmental recovery far better than any chemical test can.
But freshwater macroinvertebrates don't get much conservation attention. Some countries don't conduct surveys. There's also a shortage of people with the skills to do so.
For the study, freshwater scientists from Nigeria and Germany compiled data on freshwater macroinvertebrates from 15 African countries.
Drawing from peer-reviewed publications and the Global Biodiversity Information Facility, we included only records identified to the species level. The Global Biodiversity Information Facility is a leading international platform that provides open access to biodiversity data globally.
Also study brings scattered data into a unified and curated resource. It can serve as a foundation for modelling species distributions and guiding conservation priorities. Similar approaches have been successfully applied in regions like Europe and North America, where species distribution data have helped inform freshwater habitat protection. Ours is among the first of such efforts focused on understudied African ecosystems.
The results were startling. Most countries in this tropical belt are severely underrepresented in macroinvertebrate records.
In some cases, such as São Tomé and Príncipe, there are no records available at all. In others, like Equatorial Guinea and Togo, the number of documented records is extremely low (covering fewer than 50 species). Where such data exist, they would typically be accessible through platforms like the Global Biodiversity Information Facility or as published data.
Nigeria, the Democratic Republic of Congo, Gabon and Cameroon show better coverage with over 200 species each. These are mostly through national surveys, published studies, and contributions to global platforms. However, these numbers are modest when compared to the likely diversity in these countries. The number of species may be far higher, but limited sampling efforts and gaps in taxonomic research mean that much of this biodiversity remains undocumented. The figures don't give a complete or accurate picture of freshwater macroinvertebrate diversity.