The Oorlogskloof Nature Reserve is not only famous for its exceptionally rare Clivia’s, but is also home to the Critically Endangered Sandfish. However, what recently generated a huge amount of media interest and got conservationists in a flap was the discovery of a few rather non-descript looking mussels – largely thanks to a hungry otter.
Team members from the Cape Critical Rivers Project, a partnership between the Endangered Wildlife Trust (EWT), the Department of Environment and Nature Conservation (DENC), CapeNature and the Freshwater Research Centre (FRC), were surveying the Endangered Clanwilliam Sandfish populations in the Northern Cape’s Oorlogskloof Nature Reserve when the mussel discovery was made. Bonnie Schumann explains, “We had seen mussel shells in the Oorlogs before, but what made me stop counting fish and go off digging for mussels was when I happened to look down and there alongside me were the remains of a recent otter meal in the form of an opened mussel with bits of stringy meat on it -sure proof there were mussels in that pool!”
This is the first official record of the fresh water mussel Unio caffer in the Reserve and only the second official recording of live mussels in the entire Northern Cape Province.
These mussels have shown a sharp decline in numbers and distribution in recent years, highlighting the conservation importance of the Oorlogskloof Nature Reserve as a sanctuary, not only for endangered fish species and Bokkeveld Sandstone Fynbos, but also for freshwater mussels. Across the rest of the mussel’s range, pollution, siltation, water abstraction and a decline in water quality are all thought to be contributing to the decline of this species. Fresh water mussels are considered to be an indicator of the condition of the fresh water systems they inhabit as they are sensitive to negative changes in these systems.
Initial identification of the species was done by Dr Helen James from Rhodes University and Professor Corrie Wolmarans from North West University. Dr Ruhan Slabbert from the Stellenbosch University confirmed the identification of the species by DNA sequencing. Voucher specimens of the mussels have been lodged in the National Freshwater Snail Collection and in the Albany Museum collection where they will be available for future research.
By Bonnie Schumann, Mandy Schumann, Christy Bragg and Martine Jordaan