LIHUE — From brown tree snakes to coqui frogs, parakeets and mongoose, miconia and common rush, Kauai has a list of invasive species that have taken root, and is planning to prevent other species from arriving.

The state formed a 10-year Hawaii Interagency Biosecurity Plan in 2016 to address the introduction of invasive species. Biosecurity measures are already in place at airports, and ocean shipments are inspected for invasives.

That’s because invasive species carry with them a pretty big cost in addition to threatening native species.

The plan estimates that already-established red fire ants will cost the state $211 million per year, and the introduction of brown tree snakes could cause more than $2 billion in annual economic damage.

Recent research confirms introduced species are more likely to contribute to ecosystem changes than native species, further backing Hawaii’s biosecurity measures and confirming assertions made by members of the Kauai Invasive Species Committee.

“Implementation of a comprehensive biosecurity plan is vital in keeping alien species from being introduced to the state,” said KISC’s Ray Kahaunaele, a field operations supervisor trained in brown tree snake response.

Part of that biosecurity plan is response, as in the case of the 2018 reports of coqui frogs in the Kapahi area. Six were captured in November 2018, and the area’s gone quiet since then, according to reports.

“All areas of concern are being monitored, and so far no callers have been heard,” Kahaunaele said.

Published in The Ecological Society of America’s journal, “Frontiers in Ecology and the Environment,” the study considered the potential that native plants and animals can cause as much environmental damage as those introduced.

Authors found that’s not necessarily the case.

“Our results offer additional evidence that the biogeographic origin, and hence evolutionary history, of a species are determining factors of its potential to cause disruptive environmental impacts,” the study’s authors wrote in a statement.

Included in the results are statistics from the International Union for the Conservation of Nature’s Red List for species that have gone extinct since the year 1500. There were 953 species in total.

After analyzing those stats, they looked at the reason those species disappeared and found 300 extinctions were due, in part, to encroachment from an alien species. They also found 42 percent of those disappearances were solely due to invasive species takeover.

Some of Kauai’s endemic species have already been lost to outside encroachment. The Kauai ‘o‘o, a forest bird, disappeared in 1987, and researchers say only one specimen of the plant Brighamia insignis remains in the wild.

And while invasive species wreak havoc when they arrive, researchers point out humans have a lot to do with moving species around the planet.

That’s seen in the recent response to finding rapid ohia death fungus on Kauai trees in 2018, a fungus that started attacking the culturally important ohia on Hawaii Island in 2014 and then spread.

A full-fledged effort has been launched on multiple fronts to stop the spread of the fungus — which enters the trees through wounds in the bark — including efforts in policy-making, research and science and public education.

Of rapid ohia death, KISC Project Manager Tiffani Keanini says the next layer of defense is to avoid spreading the fungus by scrubbing all footwear clean of mud and spraying with 70-percent isopropyl alcohol after any forest activity, washing all gear and clothing, and thoroughly washing any equipment and vehicles — especially tires — that enter or are used in the forest, along roadsides, or off-road.

Authors of the study, “Alien Versus Native Species as Drivers of Recent Extinctions,” concluded biosecurity plans like Hawaii’s are some of the best ways to stop the introduction of species to a place, and encouraged more robust response to invasive species on a worldwide scale.

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Jessica Else, environment reporter, can be reached at 245-0452 or jelse@thegardenisland.com.