Restoring islands affected by exotic animals increases resilience to climate change
Everything is connected in nature. What happens in a certain place can have consequences not only in the immediate environment, but even on the other side of the planet. An international team of researchers has found that eradicating invasive species on land can lead to “impressive” improvements at sea. Hence they advocate restore islands affected by exotic plants and animals. They think it’s the best way improve the marine environment and, at the same time, increase resilience to climate change.
“Islands are home to unique plants, animals, and human societies not found anywhere else on Earth. local and global stressors threaten the persistence of island ecosystems, and invasive species are among the most damaging, yet solvable stressors,” the authors note.
While the threat of invasive land mammals to island flora and fauna is well recognized, recent studies have begun to illustrate that they also cause “extensive and destructive impacts on adjacent marine environments“, picks up the study.
“The eradication of invasive mammals and restoration of native biota are promising tools to address both island and ocean management objectives,” stress the scientists, who include Americans, New Zealanders and the UK.
The experts analyzed thousands of studies and verified that, indeed, removing invasive species and restoring island ecosystems also has significant benefits in underwater environments.
The work of the “connector species”
One of the ‘keys’ is in what they call “connector species“, those that live between the land and the ocean, such as seabirds, seals, turtles and sea snakes or crabs, which transfer nutrients from the oceans to the islands and vice versa, details the article, published in ‘Proceedings of the National Academy of Sciences’ (PNAS). “We must help them, restoring their habitats,” the scientists emphasize.
“Linking efforts on land, including the eradication of invasive mammals of the islands, with marine restoration and protection should offer benefits multiplied to achieve concurrent global conservation goals,” the report said.
“A sustained investment in monitoring on land and at sea can be used in the future to refine the planning tools science-based for integrated land-sea management“, they point out.
“As conservation professionals work to address the effects of climate changethe ocean stressors and the biodiversity crisisit is essential that we maximize returns on management investments,” the report states.
They also advocate incorporating “long-standing human knowledge of island communities through diverse perspectives of ecological and environmental sciences.”
Scientists predict “impressive” results if it works properly: “Carefully chosen conservation actions on islands can lead to truly amazing changes in the neighboring ocean ecosystem, because everything is connected.“, says Penny Becker of Island Conservation, a co-author of the study.
They give the example of seabirds, which catch their prey in the sea and then deposit nutrients on the islands through droppings, carcasses, eggs and other reproductive materials, as well as feathers and molt.
The more seabirds, the more fish
Connector species also disturb the soil through nest digging, burrowing, and other physical activities, mixing nutrients into the soil, and in some cases providing aeration.
Conversely, nutrients of terrestrial origin are introduced into the sea, for example, when land crabs spawn. In addition, the depositions of nutrients on land they can be transferred to the sea through rainfall runoff and other hydrological connections, fertilizing the nearshore environment.
Scientists documented a 27-fold difference in organic nitrogen in runoff waters between islets with and without nesting seabirds. in Palmyra Atoll, in the central Pacific, due to the prodigious excretion of these connector species.
Researchers have found that the greater the presence of seabirds on an island, the greater the number of fish in the nearby marine environment.but also faster growing and more climate resilient coral reefs.
But seabird populations are plummeting around the worldand in most cases this circumstance has to do with the introduction to the islands, due to the human activity, from non-native mammals, such as rats or other rodents, that raid nests, pigs or goats. All of this is leading some bird species to extinction.
The loss of populations of these connector species often causes “the ecosystem collapse, both on land and in the sea“, alert the authors, who demand to immediately put all the means to reverse these situations.
Reference report: https://www.pnas.org/doi/10.1073/pnas.2122354119
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