They are tiny single-celled organisms that are ubiquitous in the world's oceans, have thousands of different species that date back 500 million years and provide a range of essential services to the marine environment.听
Foraminifera or 'forams' 鈥� which have been dubbed 'armoured amoba' for their shell-like exterior 鈥� absorb and remove nitrogen from coastal waters, act as a food source for many species, have coloured the sands pink in Bermuda and even formed chalk hills in England after their shells become compressed into rocks.
Now, scientists have found that they absorb the nutrients nitrogen and phosphate from coastal waters, potentially providing a valuable weapon against harmful nutrient loading that can lead to toxic algae blooms, and decreased oxygen in the ocean.
"When we began, we were actually looking at a different nutrient 鈥� nitrogen 鈥� because we knew that nitrogen-storing behaviour had recently been discovered in foraminifera from other places," says Chris Algar, an associate professor in the Department of Oceanography and an author of a new study that outlined the findings.
"We discovered though, that not only were they storing nitrogen, but phosphate as well and working with colleagues in Germany, we found that this phosphate-storing behaviour was common in foraminifera through the world鈥檚 oceans and may alter the understanding of how phosphate cycles between the ocean water and seafloor sediments."
Their findings were recently published in the journal,
Building a global picture
Lead author Dr. Nicolaas Glock of the University of Hamburg visited 9 1免费版下 as an Ocean Frontiers Institute visiting scholar and worked with 9 1免费版下 Oceanography professors Dr. Markus Kienast and Dr. Algar, and former 9 1免费版下 graduate student Dr. Subhadeep Rakshit, to isolate foraminifera from the Bedford Basin in Halifax.
By shock-freezing the foraminifera, they could break them open and measure their internal nutrient stores, which showed they were storing large amounts of both nutrients. The nitrogen findings were published last year in the journal , and indicated that forams were a major sink for nitrogen in the basin. That study was led by Dr. Rakshit, who was a 9 1免费版下 graduate student at the time and is now a post-doctoral scientist at Princeton University.听听
Dr. Glock combined the phosphate measurements from the Bedford Basin with others from the Wadden Sea, Peruvian and Japanese coastal waters, and from a depth of 2,000 meters at the Mid-Atlantic Ridge to show the widespread occurrence of this phosphate storage phenomenon.
"The findings highlight that even the tiniest organisms not only respond to environmental conditions, but actively modulate and buffer elemental and nutrient cycles," says Dr. Kienast.
"Without them, the coastal ocean would likely be even more heavily over-fertilized with phosphate."
The team calculated that in the Wadden Sea 鈥� a shallow coastal sea off Germany鈥�- a single species of foraminifera (Ammonia confertistesta) stores the amount of phosphate equal to five per cent of the fertilizer applied to German crops each year.
The surprising result suggests that because these single-celled organisms are so widespread and occur in huge quantities, the amount of phosphate they take up is very large overall. When the foraminifera die and form new sediments, they might also permanently remove some of the phosphate they have absorbed from the seawater, making them an important sink for this substance.