Posted: June 10, 2022

Researchers Identify Sources of Nitrogen in Macroalgae in Hawaiʻi

Scientific diver collects green blades of algae at Manawai.
Scientific diver Randall Kosaki collects green blades of algae at Manawai (Pearl and Hermes Atoll) at a depth of 295 feet. Image: Stephen Matadobra/NOAA

E/V Nautilus at sea.
Scientific diver Kimberly Peyton measures canopy height of dense bed of invasive leather mudweed at a depth of 165 feet off south Oʻahu. Image: Heather Spalding/College of Charleston.

Macroalgae (algae visible to the naked eye) is sometimes called “seaweed” and holds a place in ocean health. It is generally beneficial and serves to regulate nutrient levels, including nitrogen. Excessive human-caused or natural input of nutrients such as nitrogen can cause undesirable algal blooms and outbreaks.

NOAA-sponsored researchers published the first comprehensive survey of nitrogen sources in macroalgae from shallow to mesophotic depths (0–385 feet deep) in the Hawaiian Archipelago. They compared samples from shallow and mesophotic depths in the Monument as well as the Main Hawaiian Islands.

Read about the research on the NCCOS website.