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Overview

Brief Summary

The diatom genus Pseudonitzschia (family Bacillariaceae) contains about 40 species, with a growing number of cryptic novel species defined using molecular methods.  In most species the elongate, 40-175 micrometer Pseudo-nitzschia cells form colonies, commonly of 20 or more cells, by overlapping ends to form a long thin chain-like morphology.

The genus is found in ocean and coastal waters around the globe.  In the Canadian arctic, these organisms have been found living under ice floes at sub-zero oC (<32oF) temperatures; species also flourish in tropical waters where temperatures exceed 30oC (>86oF).  When temperatures increase in high nutrient waters, “blooms” of one or more Pseudo-nitzschia species can make this genus the dominant member of the phytoplankton community, reaching numbers up to 107 cells/L.  As eutrophication and fertilization of waters increases, incidences of Pseudo-nitzschia blooms (often referred to as red tides, as these diatoms turn the water a rust color) have become more prevalent around the world.  Causes of blooms are complex and not well understood, involving changes in water conditions and nutrients sources.

During a large Pseudo-nitzschia bloom off Prince Edward Island in 1987, 100 people were sickened and 3 died after eating cultured mussels.  This incident first brought recognition of Psudo-nitzschia as a producer of Dolomic Acid (DA), a rare but naturally occurring amino acid that binds glutamate channels to act as a potent neurotoxin in vertebrates and cause permanent neurological damage.  Some animals bio-accumulate the toxin in concentrations dangerous to humans, so during blooms consumption of filter feeding shellfish, planktivorous fish such as sardines and anchovies, and internal organs of crabs should not be avoided.  Symptoms from exposure to DA are gastrointestinal and neurological in effect, and can include short-term memory loss, giving the syndrome the name Amnesic Shellfish Poisoning (ASP).  Severe cases result in death.  Sea birds and marine mammals have experienced large die-offs and strandings from eating contaminated fish prey.  After blooms the toxins may settle into sediments to further impact benthic food webs. 

Since 1987, at least 14 species of Pseudo-nitzschia have been recognized as producers of Dolomic Acid, and the genus receives a lot of attention as a major player in harmful algal blooms (HABs) around the world.  A bloom stretching along the Pacific Coast of North America from southern California to Alaska in spring of 2015 has grown to an unprecedented extent and concentration of DA in Pacific coast waters, causing high-cost closures of fishing industries.  Scientists are investigating possible connection between the bloom and higher than usual water temperatures in the area which creating conditions that may be more and more common with climate change, and developing robotic detection and modeling to assist in forecasts of future blooms.  Because species that produce DA do not do so all the time, ecology and physiology of the different species and conditions triggering toxin production are important research avenues.

For the first time ever recorded, US Pacific Coast shellfish have been found with coincident bioaccumulation of toxic Pseudo-nitzschia diatoms as well as dangerous dinoflagellates that produce Paralytic Shellfish Toxins (PSTs) in 2015.

(Anderson et al. 2010; Hayashi et al. 2007; Lelong et al 2012; Lim et al 2013; Milstein 2015; Schnetzer et al. 2007)

  • Anderson, C.R., M.R.P. Sapiano, M.B. Krishna Prasad, W. Long, P.J. Tango, C.W. Brown, and R. Murtugudde. 2010. Predicting potentially toxigenic Pseudo-nitzschia blooms in the Chesapeake Bay, J. Mar. Syst. doi:10.1016/j.jmarsys.2010.04.003
  • Hayashi, K., J.Q. Jacox, J. Glanz, N. Alvarado, R. Kudela, B.H. Rosen, and S. Coale, University California Santa Cruz. 2007. Phytoplankton Identification. Pseudo-Nitzschia. Ocean Data Center, UCSC. Retrieved June 30, 2015 from http://oceandatacenter.ucsc.edu/PhytoGallery/Diatoms/pseudo%20nitzschia.html
  • Lelong, A., H. Hégaret, P. Soudant, and S.S. Bates, 2012. Pseudo-nitzschia (Bacillariophyceae) species, domoic acid and amnesic shellfish poisoning: revisiting previous paradigms. Phycologia: March 2012, Vol. 51, No. 2, pp. 168-216.
  • Lim, H. C., Teng, S. T., Leaw, C. P. and Lim, P. T. (2013), Three novel species in the Pseudo-nitzschia pseudodelicatissima complex: P. batesiana sp. nov., P. lundholmiae sp. nov., and P. fukuyoi sp. nov. (Bacillariophyceae) from the Strait of Malacca, Malaysia. J. Phycol., 49: 902–916. doi:10.1111/jpy.12101
  • Milstein, M. 2015. NOAA Fisheries mobilizes to gauge unprecedented West Coast toxic algal bloom. Northwest Fisheries Science Center, NOAA Fisheries. Retrieved June 30, 2015 from http://www.nwfsc.noaa.gov/news/features/west_coast_algal_bloom/index.cfm
  • Schnetzer, A., P.E. Miller, R.A. Schaffner, B. Stauffer, B. Jones, S.B. Weisberg, P.M. DiGiacomo, W. Berelson, and D.A. Caron, 2007. BLOOMS OF PSEUDO-NITZSCHIA AND DOMOIC ACID IN THE SAN PEDRO CHANNEL AND LOS ANGELES HARBOR AREAS OF THE SOUTHERN CALIFORNIA BIGHT, 2003-2004. Technical Report, Southern California Coastal Water Research Project, Appendix K in Southern California Bight 2003 Regional Monitoring Program:V. Water Quality by N.P. Nezlin, P.M. DiGiacomo, S.B. Weisberg, D.W. Diehl, J.A. Warrick, M.J. Mengel, B.H. Jones, K.M. Reifel, S.C. Johnson, J.C. Ohlmann, L. Washburn, E.J. Terrill. Retrieved June 30, 2015 from http://ftp.sccwrp.org/pub/download/DOCUMENTS/TechnicalReports/528_B03_WQ_Appendix_K.pdf
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Ecology

Habitat

Depth range based on 27248 specimens in 22 taxa.
Water temperature and chemistry ranges based on 9768 samples.

Environmental ranges
  Depth range (m): 0 - 3300
  Temperature range (°C): -2.045 - 29.468
  Nitrate (umol/L): 0.030 - 34.037
  Salinity (PPS): 17.940 - 38.049
  Oxygen (ml/l): 3.756 - 9.116
  Phosphate (umol/l): 0.046 - 2.366
  Silicate (umol/l): 0.648 - 116.089

Graphical representation

Depth range (m): 0 - 3300

Temperature range (°C): -2.045 - 29.468

Nitrate (umol/L): 0.030 - 34.037

Salinity (PPS): 17.940 - 38.049

Oxygen (ml/l): 3.756 - 9.116

Phosphate (umol/l): 0.046 - 2.366

Silicate (umol/l): 0.648 - 116.089
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

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Evolution and Systematics

Functional Adaptations

Functional adaptation

Moving parts are lubricated: diatoms
 

Moving parts of diatoms may be lubricated with unique lubricants or other techniques yet to be discovered.

   
  "Ille C. Gebeshuber, Herbert Stachelberger, and Manfred Drack suggest that the study of diatoms will reveal solutions to lubrication problems at the micro and nanoscale. Three diatoms, Pseudonitzschia sp., Bacillaria paxillifer (aka B. paradoxa) and Ellerbeckia arenaria, especially warrant further study. The first two actively move, indicating some sort of lubrication exists. Entire colonies of five to 30 cells of Bacillaria paxillifer expand and contract rhythmically and are coordinated. String-like cell colonies of Ellerbeckia arenaria live in waterfalls.  They can reversibly be elongated by about one third of their original length. They might have solved their lubrication problems with techniques yet unknown to engineers. The authors mention other diatoms that might be useful to study." (Courtesy of the Biomimicry Guild)
  Learn more about this functional adaptation.
  • Gebeshuber IC; Stachelberger H; Drack M. 2005. Diatom bionanotribology--biological surfaces in relative motion: their design, friction, wear and lubrication. Journal of Nanoscience and Nanotechnology. 5(1): 79-87.
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage

Barcode of Life Data Systems (BOLD) Stats
Specimen Records:220
Specimens with Sequences:147
Specimens with Barcodes:2
Species:24
Species With Barcodes:24
Public Records:141
Public Species:24
Public BINs:1
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Barcode data

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Wikipedia

Pseudo-nitzschia

The genus Pseudo-nitzschia includes several species of diatoms known to produce the neurotoxin known as domoic acid, a toxin that is responsible for the human illness called amnesic shellfish poisoning (ASP). This genus of phytoplankton is known to form harmful algal blooms in coastal waters of Canada, California, Oregon, Washington State, Europe, Asia, Australia, New Zealand, Central America, and South America.

The general biology, physiology, toxicity and distribution of Pseudo-nitzschia species is reviewed in Bates and Trainer (2006),[1] Trainer et al. (2008),[2] Lelong et al. (2012) [3] and Trainer et al. (2012).[4]

Up until 1994, the genus was known as Nitzschia, but was changed to Pseudo-nitzschia because of the ability to form chains of cells with overlapping tips as well as other minor morphological differences.[5] The nomenclatural history is given in Hasle (1995)[6] and Bates (2000).[7]

Known species of Pseudo-nitzschia (44):

Light and electron microscope images of Pseudo-nitzschia species are shown at the Nordic Microalgae website.

Pseudo-nitzschia species that have been shown to produce domoic acid (16), although not all strains are toxigenic:

References[edit]

  1. ^ Bates, S.S. and V.L. Trainer. 2006. The ecology of harmful diatoms. In: E. Granéli an d J. Turner [eds.] Ecology of harmful algae. Ecological Studies, Vol. 189. Springer-Verlag, Heidelberg, p. 81-93. PDF; 181 KB
  2. ^ Trainer, V.L., B.M. Hickey, and S.S. Bates. 2008. Toxic diatoms. In: P.J. Walsh, S.L. Smith, L.E. Fleming, H. Solo-Gabriele, and W.H. Gerwick [eds.], Oceans and human health: risks and remedies from the sea. Elsevier Science Publishers, New York, p. 219-237. PDF 2.7 MB
  3. ^ Lelong, A., H. Hégaret, P. Soudant, and S.S. Bates. 2012. Pseudo-nitzschia (Bacillariophyceae) species, domoic acid and amnesic shellfish poisoning: revisiting previous paradigms. Phycologia 51: 168-216. PDF; 1.8 MB
  4. ^ Trainer, V.L., S.S. Bates, N. Lundholm, A.E. Thessen, W.P. Cochlan, N.G. Adams, and C.G. Trick. 2012. Pseudo-nitzschia physiological ecology, phylogeny, toxicity, monitoring and impacts on ecosystem health. Harmful Algae 14: 271–300. Publisher's abstract and link to PDF file
  5. ^ Hasle, G.R. 1994. Pseudo-nitzschia as a genus distinct from Nitzschia (Bacillariophyceae). J. Phycol. 30: 1036-1039. [1]
  6. ^ Hasle, G.R. 1995. Pseudo-nitzschia pungens and P. multiseries (Bacillariophyceae): nomenclatural history, morphology, and distribution. J. Phycol. 31: 428-435. [2]
  7. ^ Bates, S.S. 2000. Domoic-acid-producing diatoms: another genus added! J. Phycol. 36: 978-983. [3]
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