Dr Jonathon Howard, NPA Executive
New South Wales offers an abundance of stunning natural swimming spots. There is Nellies Glen in Budderoo National Park, Karloo Pools in Royal NP, as well as Glenbrook Gorge and Jellybean Pool in the Blue Mountains NP. Within our parks are a myriad of waterfalls, lagoons, lakes, creeks, and rivers, to enjoy. While they may attract crowds of people keen on water-based recreation, some of the relatively deep pools may be the only habitat that retain water throughout the year for our wildlife, which makes them important refuges for freshwater biota. So how do we balance recreation and conservation of these site?
Well recently a group of researchers looked at what influences our visits to waterholes and whether such visitation had any effects. Their study spanned nine different natural swimming holes and found that waterholes that had flowing water and deep pools were the most popular. They also found waterholes far from urban areas tended to have fewer visitors.
At each waterhole, upstream and downstream concentrations of caffeine (released through urine) and the sunscreen agent EHMC (2- ethylhexyl 4-methoxycinnamate) were measured to assess the effects of human activity. EHMC and caffeine are not normally present under natural conditions, but this study found them present in the water downstream of the waterholes that people visited.
They then checked microbial diversity downstream of waterholes, because microbial diversity in natural biofilms (the slimy coatings on submerged rocks and other structures) is a good indicator of human disturbance. They found that downstream bacterial biodiversity was reduced downstream of the water holes where EHMC and caffeine were present.
The researchers suggested that further studies be carried out to see if there are also any effects on non-microbial organisms. However, the implication is that park managers might create ways to limit visitation at high biodiversity water holes, while encouraging substantially higher visitation at water holes with deep pools and flowing water that are of lower conservation value.