The Nuwejaars River and Wetlands have enabled a significant range expansion for a freshwater mussel known as the Cape River Mussel.
Images: (c) Eugene Hahndiek
To date, there have been only five records of the species (Unio caffer) in the Western Cape, with the Nuwejaars now representing a new distribution record. The mussel was identified by the late Head Researcher for Freshwater Invertebrates at the Albany Museum, Musa Mlambo, who tragically passed away in a car accident in 2025.
Before his death, Musa described the discovery of the species in the Nuwejaars as unexpected and “really excellent news”.
He noted that further research was needed to better understand the conservation of the river systems supporting this important population.
A shrinking range
The Cape River Mussel is a freshwater species endemic to southern Africa. Although it is currently listed as Least Concern on the International Union for the Conservation of Nature (IUCN) Red List, it is threatened by ongoing river degradation.
The IUCN notes that Western Cape populations are in decline and that, aside from the Nuwejaars discovery, the species’ range in the region is shrinking. While the causes of these declines are not yet fully understood, habitat disturbance – including activities such as mining – may be a contributing factor.
Mussel memory
Members of the Nuwejaars Wetlands Strategic Management Area (NWSMA), however, say the mussel is not new to the area. Several recall seeing Cape River Mussels in the rivers since childhood.
Conrad Vlok of Strandveld Wines, a member of the NWSMA, says he has found many Cape River Mussels over the years in rivers that feed the Nuwejaars Wetlands, as well as numerous shells left behind by Cape Clawless Otters.
Another NWSMA member, Liohan Giliomee, also remembers the mussel from his youth, when it was plentiful in local rivers.
A clear call for conservation
Erica Brink, Conservation Manager for the NWSMA, says the official identification of the mussel is a clear sign that many more important finds may still lie hidden within these wetlands. “It’s exciting – there are likely freshwater species in this region that are not yet known to science, which is another crucial reason why the conservation of these wetlands must continue.”
Images: (c) Eugene Hahndiek