New Zealand pine pollen may be changing remote Pacific ecosystems: study

Pollen from New Zealand's exotic pine forests could be providing an unexpected carbon sink far out in the Pacific Ocean, government scientists said Thursday.

Pollen from the pine forests had been shown to travel more than 1,500 km through wind and ocean currents, and sink thousands of meters into the ocean to reach some of the world's deepest ecosystems, according to the National Institute of Water and Atmospheric Research (NIWA).

NIWA scientists had analysed sediment samples from the remote deep-sea ecosystems of the Kermadec and Tonga trenches north of New Zealand and found pine pollen was common.

Pollen was found to be particularly abundant in the deepest part of the Tonga Trench, which was some 10,800 meters down and the second deepest point of the world's oceans.

They concluded that pollen from exotic pine plantations might be changing these remote ecosystems.

NIWA marine biologist Dr Daniel Leduc said the steep topography of trenches was thought to funnel fine particles that sink from the surface waters of the sea, leading to high accumulation of fine material, including pollen, at their deepest point.

The study also found that areas where pollen was most abundant harbored the most life, suggesting that pollen might be a food source for some deep-sea organisms, Leduc said in a statement.

Pine pollen was observed inside small, single-celled organisms called gromiids, which ingested the pollen and could derive nutritional benefits from it.

"This unsuspected source of land-derived food originating from exotic pine plantations may be altering deep-sea food webs," said Leduc.

"Deep-sea ecosystems are typically characterized by very low availability of food sinking from the surface, and any new food source is likely to get used by the organisms that live in the sediments."

Monterey pine was introduced to New Zealand in the early 20th century, and more than a million hectares of pine forest were now established, producing an estimated 4.5 million tons of pollen each year.

"The accumulation of pine pollen may represent an unsuspected carbon sink. The gradual burial of pine pollen, part of which is highly resistant to decomposition, likely contributes to the sequestration of land-derived carbon," NIWA scientist Dr Ashley Rowden said in the statement. Endit