page_title: Prasinophyceae
section_title: Ecology
hierarchical_section_title: Prasinophyceae / Ecology
caption_attribution_description: Esquema de Micromonas pusilla by Esv.
context_page_description: The Prasinophytes or chlorophyta are a class of unicellular green algae. Prasinophytes mainly include marine planktonic species, as well as some freshwater representatives. The prasinophytes are morphologically diverse, including flagellates with one to eight flagella and non-motile unicells. The cells of many species are covered with organic body scales; others are naked. Well studied genera include Ostreococcus, considered to be the smallest free-living eukaryote, and Micromonas, both of which are found in marine waters worldwide. Prasinophytes have simple cellular structures, containing a single chloroplast and a single mitochondrion. The genomes are relatively small compared to other eukaryotes.
  Some authors treat the prasinophytes as a polyphyletic grouping of green algae from different clades. As the Tetraphytina emerged in the Prasinophytes, recently authors include it, rendering it monophyletic, and equivalent to chlorophyta.
context_section_description: A study of photosynthetic gene-sequence diversity (rbcL) in the Gulf of Mexico indicated  that Prasinophytes are particularly prevalent at the Subsurface Chlorophyll Maximum (SCM) and several different ecotypes of Ostreococcus have been detected in the environment. These ecotypes were thought to be distinguished in the environment by their adaptation to light intensities. O. lucimarinus was isolated from a high-light environment and observed year-round in the coastal North Pacific Ocean. RCC141 was considered low-light, because it was isolated from the lower euphotic zone. These strains, or ecotypes, were later shown to live in different habitats (open-ocean or mesotrophic) and their distributions do not appear to be connected to light availability. O. tauri was isolated from a coastal lagoon and appears to be light-polyvalent. Genetic data indicates that distinct molecular differences exist between the different ecotypes that have been detected.
  Prasinophytes are subject to infection by large double-stranded DNA viruses belonging to the genus Prasinovirus in the family Phycodnaviridae, as well as a Reovirus. It has been estimated that from 2 to 10% of the Micromonas pusilla population is lysed per day by viruses.
caption: Micromonas pusilla
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