The ink-black, acidic waters of the Nuwejaars wetlands and rivers hide tiny creatures that would do whatever they could to never reveal their presence. These small species have survived more than a million years – since fynbos first covered our mountains. But now they’re facing an almost unavoidable extinction, unless we act decisively.
These are the fynbos fish species that live across the Cape Fold Ecoregion. And the Nuwejaars Wetlands Special Management Area is also home to a number of these small fish.
The real threats to fynbos fish have only surfaced in the past few decades. In particular, the introduction of invasive fish species –
which not only feed on the fynbos fish, but also compete with the fish for other food sources – have sent population numbers into freefall.
The loss of habitat – such as wetlands, as well as changing climate, are adding to pressure to these species.
In our wetlands and rivers, we know of three tiny fynbos fish species. But because our water is murky, the fish are well hidden, and research is only at an early stage here. So here’s what we know:
The Heuningnes Redfin (Pseudobarbus sp. Nov Heuningnes)
This redfin is listed as Endangered. They’re known to occur in just three sub-catchments of the Heuningnes River System: the Nuwejaars River, the Grashoek River and the Kars River. The populations can’t reach each other, because of the invasive fish found between them – in particular species such as Large Mouth Bass (Micropterus salmoides) and Carp (which eat the fish eggs). A drought in recent times has severely impacted on invasive fish numbers, however, which would undoubtedly have benefited the redfins.
The Cape Galaxias (Galaxias zebratus)
This hardy fish species is believed to occur across Cape coastal streams, but little is known about it, and SANBI has listed this species as Data Deficient. Take a close look at the picture (below left), and you’ll see how translucent it is – with its internal organs even visible. This allows the Galaxias to blend into their natural environment well, to some extent protecting them against predators, although SANBI notes that alien fish are likely their biggest threat.
The Cape Kurper (Sandelia capensis)
The experts are currently undertaking work to better understand the different lineages – and so for now, the Cape Kurper is also listed as Data Deficient. But it is believed that there could be at least two different lineages. The Cape Kurper is believed to occur across the Cape Fold Ecoregion, although it is also threatened by invasive alien fish, as well as habitat destruction and water abstraction.
The Heuningnes Galaxias (Galaxias sp nov heuningnes)
The South African National Biodiversity Institute (SANBI) says this galaxia is found in the Heuningnes and Ratel River systems – including the Upper Kars River and the Nuwejaars subcatchment. They seem to prefer static water or slow-flowing waters, and like the indigenous vegetation found in the streams. The species is listed as Endangered, given the threats of invasive fish.
Getting the environment right
For these fish species to flourish in our wetlands and rivers, we need to create the right environment for them. That’s why our rehabilitation work, supported by WWF South Africa to remove invasive plants and plant indigenous vegetation, and our research efforts supported by the Hans Hoheisen Charitable Trust, serve as the first steps in supporting population numbers. The indigenous plants provide spots to hide from invasive fish. They also consume much less water than thirsty invasive trees, so pools and streams can last into the summer season.
But we also need to know more, and work with partners where possible to research our species, the threats to them, and the possible solutions. This work is still at an early stage, and we look forward to sharing more as we discover more.
Images: LoveGreen Communications & Nuwejaars team