Originally, the forests of the Ogasawara Islands were inhabited by countless woodlouse and gammaridea under the fallen leaves, and played an important role in nurturing rich soil as a forest decomposer.However, since the 1980s, these soil animals have begun to disappear rapidly.First, the decline began on Chichijima, and now it is almost impossible to see it.Next, on Hahajima, the number dropped sharply in most areas.
Shotaro Shinobe (1st year master's student) of the Graduate School of Life Sciences, Tohoku University and others found that the culprit of this strange soil animal "mass disappearance", which had been a mystery for many years, was in the 1980s. At first, I found out that it is a kind of terrestrial stringworm, a foreign organism that invaded Ogasawara.
Experiments investigating the eating habits of terrestrial worms have shown that they prey on arthropods such as the woodlouse, gammaridea, spiders and insects.In addition, a survey of Hahajima revealed that the woodlouse and gammaridea were almost completely destroyed at the invasion point of the terrestrial worms, and that the total number of arthropods in the soil was also drastically reduced.In the southern part of Hahajima, the distribution area of terrestrial worms gradually expanded to the south, but it was also found that the area where soil arthropods were scarce also expanded to the south in synchronization with it.So far, there is no way to deter this, and it is expected that the soil ecosystem on Hahajima will soon be destroyed.
This is the first time in the world that alien terrestrial worms have been shown to cause great damage to the ecosystem.The results show that it is difficult to accurately predict the risks of alien species invasion to the ecosystem in advance.In Ogasawara, the status of invasion of terrestrial Ribbon worms to islands other than Chichijima and Hahajima is unknown, so it is urgently necessary to investigate the distribution and take measures to prevent the spread of terrestrial worms to uninvaded islands.
Paper information:[Scientific Reports 7] Declining soil Crustacea in a World Heritage Site caused by land nemertean
