In emergencies, dumping ocean water on fires may be the best option. But seawater can have long-term effects on equipment and ecosystems, as a novel coastal experiment shows.

Saltwater corrodes firefighting equipment and may harm ecosystems, especially those like the chaparral shrublands around Los Angeles that aren’t normally exposed to seawater. Gardeners know that small amounts of salt – added, say, as fertilizer – does not harm plants, but excessive salts can stress and kill plants.