Toxic Invader is the fifth episode of the first season of Jeremy Wade's Dark Waters.
Episode Description[]
Something is wiping out the fish in the Australia's Fitzroy River, and Jeremy Wade is determined to discover the cause. Evidence points to the arrival of a new top predator, but could something far more insidious be spreading into Western Australia?
Episode Summary[]
Jeremy has heard all sorts of interesting reports from the Fitzroy River in Australia. Something seems to have gone wrong in this region in recent years, and since the Fitzroy is 400 miles long, and very remote, Jeremy does not feel like human interference is a logical explanation.
Jeremy travels to a local bar, where his suspicions are confirmed. He hears of Saltwater Crocodiles being found much further up the Fitzroy, and their increasing aggression. To Jeremy, that indicates competition. Initially suspecting another predator is driving these crocodiles to take drastic measures, Jeremy fishes in brackish creeks near the river. However, just like in the Amazon, small, aggressive fish seem to be beating bigger predators to the bait.
Jeremy then asks on a local radio, and hears that things have indeed been changing on the Fitzroy. He also hears that these happenings do not only come from the mouth, and that they stem from the upper reaches of the river. Travelling upstream, Jeremy tries to fish near the bank of a river, but only hooks a turtle. According to Jeremy, its possible that only animals with tough shells can survive whatever has arrived in this region.
On his way further up the Fitzroy, Jeremy sees a warning of an invasive species called a Cane Toad. Perhaps this highly toxic species is to blame for the problems afflicting this remote waterway. Stopping by a village, Jeremy hears accounts of what this species has done. They were initially introduced from South America to Queensland to control beetles, but have spread all across Australia at a rate that has grown from 2 to 50 kilometers on average per year. The toads in Western Australia even appear to have evolved 25% longer back legs allowing them to cover more ground than their Queensland and South American counterparts.
Jeremy is able to catch a Toad, and realizes just how well they are camouflaged. Jeremy sets out to discover how much damage this species has done to the already occupied portions of the continent. On his way deeper into Cane Toad territory, Jeremy stops at a hotel and sees a porch completely covered by young toads. Crocodiles, Barramundi, and even catfish across Australia seem to be feeling the blunt of this attack. Consuming a single Cane Toad proves to be fatal to most Australian predators.
Jeremy teams up with a scientist who scours the beaches on a man made lake to search for dead crocodiles killed by Cane Toad consumption. According to this expert, the most affected crocodiles are the sub adults. Crocodiles only attack prey that they can eat, and so babies will only attack very small Cane Toads. At this stage, the toads are less lethal, and the baby crocodiles will probably survive. After this, they will associate the bad experience with the toads, and hopefully not attempt to attack them in the future.
Jeremy is able to pull up a few catfish, but this species is a bottom feeder that lives primarily in water too deep for Cane Toads to ever venture into. Jeremy then sets out to catch the iconic Barramundi, to see if the species has survived. Travelling back to the river mouth of the Fitzroy, Jeremy fishes in some brackish pools, and eventually catches one of these too. It appears even this predatory species has adapted to the invader, and survived countless contacts.
Even though the Cane Toad invasion cannot be stopped, the native species of Western Australia have adapted to cope with this new assailant. It is possible that the terrible toll this species has taken on this region will diminish in the coming years.
Trivia[]
- This episode is similar to an episode of Mighty Rivers.