Algae-killing virus stimulates nutrient recylcing in the oceans

July 18 (UPI) -- All of the ocean's many complex food chains rely on nutrients. Nutrient cycles fuel algae and phytoplankton blooms, which nourish the smaller life forms that feed larger predators.

Nutrient recycling is essential for ecological health and marine biodiversity. New research suggests viruses help promote the turnover of vital nutrients.

According to the new study, published this week in the journal Nature Microbiology, viruses can accelerate mortality among single-celled algae called diatoms. When diatoms perish, their decomposition provides fresh nutrients and organic matter for other types of algae.

Scientists determined certain environmental conditions can encourage the spread of viral infections among diatoms, further accelerating nutrient recycling.

Because diatoms produce roughly 20 percent of the planet's oxygen, as well as help keep CO2 sequestered in the oceans, it is essential that climate scientists understand how the algae will respond to climate change.

"To our knowledge, this is the first time different stages of infection have been diagnosed in natural diatom populations and suggests that diatom populations may be terminated by viruses," senior study author Kim Thamatrakoln, an associate research professor of marine sciences at Rutgers University-New Brunswick, said in a news release. "Our study showed that when silicon levels in the ocean are low, diatoms can be more rapidly infected and killed by viruses and are then more likely to release their nutrients and other matter in the surface ocean instead of sinking."

Because diatoms build their cell walls out of silicon dioxide, or glass, scientists assumed the algae sink to the bottom of the ocean when they die, preventing surface-level nutrient recycling. Until recently, scientists also assumed diatoms and their glass cell walls were impervious to viral infections. But recent studies showed diatoms can be infected by the smallest viruses on the planet.

During a survey of diatom blooms and die-offs among California's coastal waters, scientists found strong correlations between die-off patterns and rates of viral infection. Researchers also found increased rates of viral infection among diatoms where surface waters were low in silicon.

"We found a link between Si stress and the early, active and lytic stages of viral infection," researchers wrote in their paper.

The new research suggests the combination of silicon availability and viral loads play an important roll in controlling the growth of diatom populations throughout the world's oceans.