"Palmyra had been an isolated and tranquil Pacific atoll, until a 20th-Century invasion of black rats arrived, setting the whole atoll’s ecology hurtling down a different path.

During World War Two, the US military stationed thousands of sailors on the Palmyra Atoll, a ring of pristine,..."Palmyra had been an isolated and tranquil Pacific atoll, until a 20th-Century invasion of black rats arrived, setting the whole atoll’s ecology hurtling down a different path.

During World War Two, the US military stationed thousands of sailors on the Palmyra Atoll, a ring of pristine, coral-fringed islets in the Central Pacific Ocean. But the ships also brought a host of stowaways to the islands: black rats. On warm, wet Palmyra, the rodents thrived, quickly multiplying and feasting on young crabs, tree seedlings, and seabird eggs and chicks. Invasive coconut palms from abandoned plantations spelled further trouble for the birds, depriving them of their native habitat.

By the end of the century, the rats and palms had transformed the atoll’s entire ecosystem. Eight seabird species roaming the wider area were ominously missing – according to conservationists, possibly because the rats had driven them into local extinction. Some crab species were dwindling, or had even completely disappeared from sight. On other tropical islands, evidence emerged that rodent invasions were affecting species as ostensibly far-removed as coral reefs, by disrupting their supply of nutrient-rich seabird droppings.

The coconut palms also damaged the delicate chain of nutrients that sustained life on and around Palmyra. They took over half the atoll. Seabirds avoided nesting in the palms, preferring sturdy native trees with branches. As the supply of bird droppings declined, the impact rippled through the ecosystem. On islets with palm forests, the soil was poorer in nutrients than on those with native forests, as was the water running off them. The plankton along the palm forest coastlines was less abundant, and there were fewer manta rays, which feed on plankton, than along native forest coastlines."

.. read more at bbc.in/3iPppJ5

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