After analyzing in detail 727 studies carried out in the last 70 years on 2,500 animal species, researchers from the Department of Environmental Science at the University of California at Berkeley have concluded that the massive and catastrophic deaths of animals in this area have increased. period.
Birds, fish and marine invertebrates are the most affected zoological groups , while among mammals the figures have remained stable and among reptiles and amphibians there has been a slight decrease in mortality. These cases of massive mortality imply that a high percentage of the population dies in a short period of time.
Although they are not very frequent, they pose a devastating blow that can kill more than 90% of the individuals of a species in one stroke. Stephanie Carlson, a professor at Berkeley and one of the study’s authors, indicates that this is ” the first attempt to quantify the patterns of frequency , magnitude and causes of these catastrophes that lead to mass deaths.”
The researchers took into account records of these events collected by the scientific literature as early as the 19th century, but focused mainly on the period from 1940 to the present. Although they think that the increase in deaths is due in part to more and more information about these events that may have been ignored in the past, they believe that for certain animals the sad figures are clearly higher.
Diseases are responsible for 26% of mass deaths , while 19% can be attributed to the direct effects of human actions , such as pollution. Biotoxicity produced by excessive algal blooms, a process that can be attributed to climate change, is responsible for 25% of deaths.
