huxleyi

Emiliania huxleyi is a species of unicellular marine phytoplankton belonging to the coccolithophores, a group within the Haptophyta. It is widely distributed in temperate and tropical oceans and is known for forming expansive, optically detectable blooms that can cover large areas of the sea surface. These blooms contribute to the color and light scattering of coastal and open-ocean waters and are frequently monitored from space.

Biology and morphology: E. huxleyi cells are covered with calcium carbonate coccoliths, microscopic plates that form a chalk-like coating around the cell. The organism is photosynthetic, using light energy to fix carbon dioxide. It exhibits a haploid-diploid life cycle with alternating generations; the two stages can differ in motility and morphology, influencing population dynamics and bloom behavior.

Ecology and ecological significance: E. huxleyi blooms are influenced by nutrient availability, temperature, light, and grazing, and they can be terminated rapidly by viral infections, notably from the Emiliania huxleyi virus (EhV). The coccoliths produced by E. huxleyi contribute to the oceanic carbon cycle by sequestering inorganic carbon in CaCO3 as they sink, forming part of long-term sedimentary records. Fossil coccoliths from this and related species are abundant in marine sediments and have shaped carbonate geology through geological time.

Research and significance: E. huxleyi is a widely studied model organism in marine biology, ecology, and paleoceanography. Its blooms are observable by satellite sensors due to coccolith reflectance, aiding population and climate studies. Genomic resources support investigations into calcification, viral interactions, and carbon cycling, while ongoing work examines how ocean acidification and warming may affect calcification and bloom dynamics.