Researchers at the University of California Los Angeles, Yale University and UC Berkley have reported in the Proceedings of the National Academy of Sciences their results after careful examination of 727 animal mass mortality cases. These cases of mass mortality in animals amassed 2,500 species over the last 70 years.
The examination of all 727 mass mortality in animals cases have revealed that the number of mammals dying in masses has remained unchanged, while the number of reptiles and amphibians dying in masses is decreasing. What is quite worrying, is the fact that these die-offs are becoming more and more frequent in fish, birds and marine invertebrates.
While mass mortality in animals are still quite a rare occurrence, the events do occur enough to have scientists start worrying. According to the study, these mass mortality in animal cases can have the potential to claim 90% or even more of a species population in one instance.
Stephanie Carlson, study senior author, revealed that:
This is the first attempt to quantify patterns in the frequency, magnitude and cause of such mass kill events.
So what is killing these animals in such high numbers? After careful examination of the cases of mass mortality in animals, the scientists have revealed that the primary cause is disease which accounts for 26% of the mortality cases. The second cause that accounts for 19% of the cases is adverse environmental effects that are caused by humans. Biotoxicity events also contributed to the number of mass mortality in animal events, as did climate change, which accounted for 25% of the cases.
The researchers did say that the some of the most severe cases of mass mortality in animals weren’t brought off by one single cause, but a multitude of causes. They go on to give the example of federal fish, which have been killed by summer drought, as well as low oxygen levels in the water.
The researchers of this study have suggested that in order to understand the causes of mass mortality in animals monitoring of both physical and biological changes in the environment is vital.
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