By Prof. Gordon T. Taylor, Stony Brook University (corp2365, NOAA Corps Collection) [Public domain], via Wikimedia Commons

This article was originally published on Phys.org


“Phytoplankton, unicellular photosynthetic microbes, play a fundamental role in the global carbon cycle and fuel marine food webs. Globally, phytoplankton productivity is regulated by the availability of essential nutrients such as nitrogen and iron. Researchers at the GEOMAR Helmholtz Centre for Ocean Research, Kiel, have now been able to show that the growth of phytoplankton over large extents of the ocean is not limited by a single nutrient, but by multiple nutrients simultaneously. The study has been published today in the top scientific journal Nature.

Fluxes of nutrients to the surface ocean are changing. Such changes will almost certainly influence  productivity and impact  and the carbon cycle. But how, exactly, will phytoplankton productivity be affected? In order to answer this question, it is important to know which nutrients limit phytoplankton  in the ocean. Measurements of nutrient concentrations in the ocean have shown widespread depletion of multiple elements simultaneously. However, to date, no experimental studies have convincingly demonstrated so-called co-limitation of growth by more than one nutrient over large extents of the ocean.

An international research team led by the marine biogeochemist Dr. Thomas Browning from the GEOMAR Helmholtz Centre for Ocean Research, Kiel, has now shown that over broad regions of the South Atlantic, a combination of two nutrients was needed to stimulate any phytoplankton growth, while in some cases, three separate nutrients were required to maximize growth. The team has published its results in the scientific journal Nature. “Nutrient co-limitation has been proposed many times before. However, we were able to prove it experimentally over large oceanographic extents for the first time,” says Dr. Browning…”

Read on at: Phys.org.