AsianScientist (Apr. 4, 2018) – A research group in Japan has devised a single measurement to understand how wildlife populations are affected by major natural events such as hurricanes, severe winters and tsunamis. They published their findings in Scientific Reports.
Conservationists and ecologists need to be able to predict the impacts of extreme natural events on species so as to improve their understanding of how these events influence natural selection.
However, the physical units used to describe natural events, such as wind speed for hurricanes, wave height for storms and moment magnitude for earthquakes, vary widely, making it impossible to directly compare their intensity. Coupled with the problem of normal fluctuations in wildlife populations, scientists currently face difficulties in judging the impact of extreme natural events on wildlife.
In the present study, researchers at Hokkaido University, Japan, used a single unit of measurement called a ‘return period’ to quantify how long it takes for a species’ population to rebound after an extreme event.
The researchers plotted the return periods of 27 natural events that occurred between 1946 and 2011 against the severity of their impact on 50 species. They found that wildlife populations declined more severely in response to physically intense events occurring less than two times in a hundred years.
The scientists observed a smaller decline in wildlife populations from physically weak but frequent events, suggesting that these lower-intensity but higher-frequency disturbances (relative to the life span of an organism) exert a stronger selection pressure on species, resulting in adaptations to resist such disturbances.
Their findings suggest that the 2011 tsunami had a relatively small impact on inhabitants of Japan’s rocky tidal shoreline, such as mussels, barnacles and algae.
“This unexpectedly limited impact could be because the tsunami only lasted a few hours,” said Dr. Takashi Noda of Hokkaido University who led the study.
The team emphasized that long-term censuses of organisms are urgently needed to improve predictions of how natural events affect wildlife.
The article can be found at: Iwasaki & Noda (2018) A Framework for Quantifying the Relationship Between Intensity and Severity of Impact of Disturbance Across Types of Events and Species.
———
Source: Hokkaido University; Photo: Shutterstock.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.
