World Library  
Flag as Inappropriate
Email this Article


Article Id: WHEBN0017190038
Reproduction Date:

Title: Picoeukaryote  
Author: World Heritage Encyclopedia
Language: English
Subject: Plankton, Picobiliphyte, Eukaryotes, Nanophytoplankton, Thin layers (oceanography)
Collection: Aquatic Ecology, Biological Oceanography, Eukaryotes, Planktology
Publisher: World Heritage Encyclopedia


Picoeukaryotes are atomic size, the term was likely used to avoid confusion with existing size classifications of plankton.


  • Characteristics 1
    • Cell structure 1.1
    • Distributions 1.2
    • Diversity 1.3
  • Ecology 2
  • Biological characteristics 3
  • See also 4
  • Notes 5
  • External links 6


Cell structure

Picoeukaryotes can be either Ostreococcus tauri, an autotrophic picoeukaryote belonging to the class Prasinophyceae, contains only the nucleus, one mitochondrion and one chloroplast, tightly packed within a cell membrane. Members of a heterotrophic class, the Bicosoecida, similarly contain only two mitochondria, one food vacuole and a nucleus.[1]


These organisms are found throughout the water columns. Autotrophic picoeukaryotes are restricted to the upper 100–200 m (the layer that receives light) and are often characterized by a sharp cell maximum near the Deep Chlorophyll Maximum Layer (DCML)[2] and decrease significantly below.[3] Heterotrophic groups are found at greater depths and for example, in the Pacific Ocean, they have been found in the vicinity of hydrothermal vents at depths up to 2000–2550 m. Some heterotrophic lineages are found, unstratified, at all depths from the surface down to 3000 m.[1] They show high phylogenetic diversity[4][5] and high variability in global cell concentrations, ranging from 107 to 105 liter−1.[3]


primary productivity.[8] Although much less abundant than cyanobacterial Photosynthetic picoplankton they have been shown to be as important in terms of biomass and primary production than picocyanobacteria.[9] In more oligotrophic environments, such as Station ALOHA, researchers believe that approximately 80% of the chlorophyll α biomass is due to cells in the pico-size range.[2] Analysis of rDNA sequences indicate that heterotrophic oceanic picoeukaryotes belong to lineages such as the Alveolata, stramenopiles, choanoflagellates, and Acantharea.[5] In these lineages, many groups do not have cultured representatives yet. Grazing experiments have demonstrated that novel stramenopile picoeukaryotes are bacterivorous.[4]


Since the size of these organisms determines how they interact with their environment, it is no surprise that they are not known to form significant sinking organic aggregates.[10] Their contribution to carbon cycling is difficult to assess because they are difficult to separate by techniques such as filtration.[11] Recent fluorescent in situ hybridization (FISH) experiments have shown that picoeukaryotes are fairly abundant in the deep sea.[1] Increased resolution with the development of better FISH techniques indicates that study and detection should become easier.[12] Research has also shown that picoeukaryotes have a strong correlation with chlorophyll concentrations in both meso-autotrophic reservoirs and hypereutrophic reservoirs.[13] Moreover, nitrogen enrichment experiments suggest that picoeukaryotes have an advantage over larger cells when it comes to acquiring nutrients because of their large surface area per unit volume. They have exhibited more effectiveness in the uptake of photons and nutrient from low-resource environments.[8]

Biological characteristics

Picoeukaryotes, much like other planktonic species, are exposed to light variations during the diel cycle and due to vertical displacement in the mixed layer of the water column. They have specialized biological reactions to help them deal with excessive densities of light, such as the Xanthophyll cycle.[14]

See also


  1. ^ a b c
  2. ^ a b Campbell, Lisa and Daniel Vaulot. Photosynthetic picoplankton community structure in the subtropical north pacific ocean near Hawaii (station ALOHA). Deep-Sea Research 1, Vol. 40, No. 10, pp. 2043-2060 (1993). Accessed April 30, 2008.
  3. ^ a b Hall, J.A. and W.F. Vincent. Vertical and horizontal structure in the picoplankton communities of a coastal upwelling system. Marine Biology 106, 465-471 (1990). Accessed April 30, 2008.
  4. ^ a b c Massana, R. et al. Unveiling the Organisms behind Novel Eukaryotic Ribosomal DNA Sequences from the Ocean. Applied and Environmental Microbiology, 4554-4558 (2002). Accessed April 30, 2008
  5. ^ a b Moon-van der Staay, S. et al. Oceanic 18S rDNA sequences from picoplankton reveal unsuspected eukaryotic diversity. Nature 409, 607-610 (2001). Accessed April 30, 2008.
  6. ^
  7. ^
  8. ^ a b Fouilland, E. et al. Productivity and growth of a natural population of the smallest free-living eukaryote under nitrogen deficiency and sufficiency. Microbial Ecology 48, 103–110(2004). Accessed April 30, 2008.
  9. ^
  10. ^ Waite, A.M. et al. Mass Sedimentation of Picoplankton embedded in Organic Aggregates. Limnology and Oceanography. Vol 45, No. 1, 87-97 (2000). Accessed April 30, 2008.
  11. ^ Worden, A. Z. et al. (2004). Assessing the dynamics and ecology of marine picophytoplankton: The importance of the eukaryotic component. Limnology and Oceanography 49: 168-79.
  12. ^ Biegala, I.C. et al. Quantitative Assessment of Picoeukaryotes in the Natural Environment by Using Taxon-Specific Oligonucleotide Probes in Association with Tyramide Signal Amplification-Fluorescence In Situ Hybridization and Flow Cytometry. Applied and Environmental Microbiology, 5519-5529 (2003). Accessed April 30, 2008.
  13. ^ Wang, Baoli et al. The distributions of autumn picoplankton in relation to environmental factors in the reservoirs along the Wujiang River in Guizhou Province, SW China. Hydrobiologia 598:35–45 (2008). Accessed April 30, 2008.
  14. ^ Dimier, Celine. et al. Photophysiological properties of the marine picoeukaryote Picochlorum RCC 237 (Trebouxiophyceae, Chlorophyta). J. Phycol. 43, 275–283 (2007). Accessed April 30, 2008.

External links

  • MicrobeWiki A site on a biology Wiki run by Kenyon College
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.