Certain types of volcanic ash do not dissolve easily in water. Instead, they clump on the surface of the ocean in pumice rafts. These rafts can clog salt water intake strainers very quickly, which can result in overheating of shipboard machinery dependent on sea water service cooling.
As of July 2017, the International Union for Conservation of Nature (IUCN) lists <em><u>455</u></em> critically endangered fish species. Hope this helps!
