When it comes to invasive species in the United Kingdom, a few ounces of hot water may be worth nearly £2 billion in annual management costs, according to a new study. Hardy enough on their own, invasive, aquatic species like the killer shrimp and zebra mussel have also had help spreading into various watersheds from the country’s anglers and canoeists, hitchhiking along on their nets, waders, and other water equipment. Now, new research, published in Biological Invasions, has found that dunking that equipment after use in hot water for 15 minutes could help prevent the invaders from catching a lift. Researchers placed four species of nonnative plants—curly water thyme, New Zealand pigmyweed, floating pennywort, and parrot’s feather—and three species of nonnative animals—zebra mussels, killer shrimp, and bloody red mysid—in angling nets. They then tested the effectiveness of four treatments on mortality rates: hot water (about 45°C) only, hot water and drying, drying only, and a control group. Hot water baths, they found, were extremely effective in dealing with the unwanted species. In fact, all plant and animal species were dead within 1 hour of treatment, except for the New Zealand pigmyweed, which had 90% mortality for the same conditions. The hot water and drying method showed similar results. It took about 7 days, however, for the air-dried nets to reach comparable mortality rates, and in the control group, where the nets remained damp, all the species except for the bloody red mysid survived for a little more than 2 weeks. Previous research has shown that about 64% of anglers and nearly 80% of canoeists visit more than one watershed in a 2-week period. Only a fraction of them clean their equipment in between, leaving plenty of opportunity for accidental transfers, scientists say.