HNLC
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HNLC stands for "high-nutrient, low-chlorophyll" - a term used in marine ecology to describe areas of the ocean where the number of phytoplankton (standing stock) are low in spite of high macro-nutrient concentrations (nitrate, phosphate, silicic acid). HNLC is thought to be caused by the scarcity of iron (a micro-nutrient which phytoplankton require for photosynthesis) and high grazing rates by micro-zooplankton that feed on the phytoplankton. The HNLC condition has been observed in the equatorial and subarctic Pacific Ocean, the Southern Ocean, and in some strong upwelling regimes, such as off central and northern California and off Peru.
