Data from: Fine tuning for the tropics: application of eDNA technology for invasive fish detection in tropical freshwater ecosystems.

Invasive species pose a major threat to aquatic ecosystems. Their impact
can be particularly severe in tropical regions, like those in northern
Australia, where >20 invasive fish species are recorded. In
temperate regions, environmental DNA (eDNA) technology is gaining momentum
as a tool to detect aquatic pests, but the technology’s effectiveness has
not been fully explored in tropical systems with their unique climatic
challenges (i.e. high turbidity, temperatures and ultra-violet light). In
this study, we modified conventional eDNA protocols for use in tropical
environments using the invasive fish, Mozambique tilapia (Oreochromis
mossambicus) as a detection model. We evaluated the effects of high water
temperatures and fish density on the detection of tilapia eDNA, using
filters with larger pores to facilitate filtration. Large–pore filters (20
μm) were effective in filtering turbid waters and retaining sufficient
eDNA, whilst achieving filtration times of 2-3 minutes per 2-L sample.
High water temperatures, often experienced in the tropics (23, 29, 35 °C),
did not affect eDNA degradation rates, although high temperatures (35 °C)
did significantly increase fish eDNA shedding rates. We established a
minimum detection limit for tilapia (1 fish/ 0.4 megalitres/ after 4 days)
and found that low water flow (3.17 L/s) into ponds with high fish density
(>16 fish/ 0.4 megalitres) did not affect eDNA detection. These
results demonstrate that eDNA technology can be effectively used in
tropical ecosystems to detect invasive fish species.