The Rate of Heating Might be the Fish Killer

A paper (in the Proceedings of the National Academy of Sciences of the USA) has raised the possibility that the rate at which the water heats (rather than the final temperature attained) is the factor accounting for the mass deaths of coral reef fish (https://www.pnas.org/content/early/2020/09/15/2009748117). A study on fresh carcasses collected at an event off Eilat (Israel) found that several of the fish had died following a major infection with a bacterium Streptococcus iniae. The bacterium is normally found in most reef fishes (it's what is known as a latent infection) but it appeared that the heating event prevented the immune system of the fish from keeping it in check. The water temperatures attained were not extreme but the warming occurred over just a few days, rather than by following a seasonal pattern. Similar mass reef fish deaths had been recorded in Kuwait bay in 2001 and in an Australian location in 2011. Again, the deaths were preceeded by a very rapid warming of the waters in these same areas. It appears than some of the negative consequences of climate change occur because the organisms don't have time to adapt.