title: Fine-tuning for the tropics: application of eDNA technology for invasive fish detection in tropical freshwater ecosystems.
abstract: 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 ultraviolet 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 min 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.
authors: College of Marine and Environmental Sciences, James Cook University, Townsville, Qld, 4811, Australia.|TropWATER-Centre for Tropical Water & Aquatic Ecosystem Research, James Cook University, Townsville, Qld, 4811, Australia.|Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville, Qld, 4811, Australia.|Centre for Tropical Biology and Climate Change, James Cook University, Townsville, Qld, 4811, Australia.
authors: Heather L A
authors: HL
authors: Robson
authors: College of Marine and Environmental Sciences, James Cook University, Townsville, Qld, 4811, Australia.|TropWATER-Centre for Tropical Water & Aquatic Ecosystem Research, James Cook University, Townsville, Qld, 4811, Australia.|Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville, Qld, 4811, Australia.
authors: Tansyn H
authors: TH
authors: Noble
authors: College of Marine and Environmental Sciences, James Cook University, Townsville, Qld, 4811, Australia.|Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville, Qld, 4811, Australia.|Queensland Department of Agriculture & Fisheries, Townsville, Qld 4814, Australia.
authors: Richard J
authors: RJ
authors: Saunders
authors: College of Marine and Environmental Sciences, James Cook University, Townsville, Qld, 4811, Australia.|Centre for Tropical Biology and Climate Change, James Cook University, Townsville, Qld, 4811, Australia.
authors: Simon K A
authors: SK
authors: Robson
authors: TropWATER-Centre for Tropical Water & Aquatic Ecosystem Research, James Cook University, Townsville, Qld, 4811, Australia.
authors: Damien W
authors: DW
authors: Burrows
authors: College of Marine and Environmental Sciences, James Cook University, Townsville, Qld, 4811, Australia.|TropWATER-Centre for Tropical Water & Aquatic Ecosystem Research, James Cook University, Townsville, Qld, 4811, Australia.|Centre for Sustainable Tropical Fisheries and Aquaculture, James Cook University, Townsville, Qld, 4811, Australia.
authors: Dean R
authors: DR
authors: Jerry
mesh_terms: D000818:Animals; D001315:Australia; D058448:Biota; D004247:DNA / Q000235:genetics / Q000302:isolation & purification*; D005618:Fresh Water / Q000737:chemistry*; D005828:Genetics, Population / Q000379:methods*; D058865:Introduced Species; D008967:Molecular Biology / Q000379:methods; D011156:Population Density; D013696:Temperature; D017210:Tilapia / Q000145:classification* / Q000235:genetics*; D014329:Tropical Climate
chemical_list: D004247:DNA
keywords: Mozambique tilapia; Oreochromis mossambicus; cichlid; eDNA filtration; environmental DNA