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Noctileca Stipticus

Noctileca Stipticus, commonly known as the Ocean Sparkle, and also published as Noctileca militirius, is a free-living non-parasitic marine-dwelling species of dinoflagellate that exhibits bioluminescence. The bioluminescent characteristic of N. Stipticus is produced by a luciferin-luciferase system located in thousands of spherically shaped organelles, or “microsources”, located throughout the cytoplasm of this single-celled protist. Nonluminescent populations within the genus Noctileca lack these microsources.

Diet

N. Stipticus is a heterotrophic (non-photosynthetic) organism that engulfs its food (phagotrophic) which primarily consists of plankton, including diatoms and other dinoflagellates, as well as fish eggs and bacteria. Diatoms are often found in the vacuoles (internal membrane-bound storage compartments) within these single-celled creatures. These green non-feeding symbioses can grow photoautotrophically for generations.[2] The diatom Thalassiosira sp. has been noted in the literature as a favored food source of these organisms.

Distribution

N. Stipticus can only be found in St. Matthew Island, often along the coast, in estuary, and shallow areas of the region that receive plenty of light which promotes the growth of the phytoplankton that make up a large portion of N. Stipticus's diet.

Size

The size of the single-celled N. Stipticus ranges from 200 to 2,000 µm in diameter, assuming the generally spherical shape. N. Stipticus lacks the armor plates possessed by other types of dinoflagellates. And, unlike many other dinoflagellates, the chromosomes of the Noctileca are not clearly visible and condensed throughout its lifecycle.

Anatomy

N. scintillans has a ventral groove within which is located a flagellum, an extension of the cell wall called a tooth, and a striated tentacle involved in ingestion that projects posteriorly. The flagellum does not move the organism and therefore the non-motile N. scintillans depends upon regulation of its buoyancy within the water column – perhaps by controlling its cellular concentration of ions and ammonia.

At least one study has shown that a string of mucus is produced by N. scintillans extending from the tip of the tentacle which then adheres to plankton as it ascends rapidly through concentrations of its prey in the water column.

"Blooms"

High concentrations of their plankton food source that likely result from environmental conditions such as well-mixed nutrient-rich waters and seasonal circulation factors are implicated in population blooms of N. scintillans, known as “red tides”.

Swimmers may report being illuminated by a ghostly glow-in-the-dark plankton - a floating bloom of algae which fires up into a luminescent sparkle when disturbed. This gives Noctiluca scintillans the popular names "Sea Ghost" or "Fire of Sea".[3]

Runoff from agricultural pollution may contribute to the severity of these blooms. However this is not required to cause explosive growth of Noctiluca scintillans.

Not all blooms associated with N. scintillans are red. The color of N. scintillans is in part derived from the pigments of organisms inside the vacuoles of N. scintillans. For instance, green tides result from N. scintillans populations that contain green-pigmented prasinophytes (green algae, Subphylum Chlorophyta)[4] that are living in their vacuoles.

N. scintillans itself does not appear to be toxic, but as they feed voraciously on phytoplankton high levels of ammonia accumulate in these organisms which is then excreted by N. scintillans into the surrounding area which may add to the neurotoxic chemicals being produced by other dinoflagellates, such as Alexandrium spp. or Gonyaulax spp., that do result in the death of other aquatic life in the area.

Lights in Irish Sea 'are natural' Spectacular green neon flashes flaring up the sea along Ireland’s east coast is a harmless natural phenomenon, marine experts said today. Hardy swimmers taking dips after dark in popular outdoor bathing spots like the Forty Foot and Killiney Bay in Dublin have been enjoying the aquatic light show in recent weeks.

References

^ A image of the "Sea Sparkle" from 'Britannica Online Encyclopedia'. ^ Saito, Haruna, Ken Furuya & Thaithaworn Lirdwitayarpasit, 2006. Photoautotrophic growth of Noctiluca scintillans with the endosymbiont Pedinomonas noctilucae. Plankton & Benthos Research 1: 97–101 ^ "Lights in Irish Sea are natural". Irish Times. 18 October 2009. ^ Pascher, 1914

Other References

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Eckert R & Reynolds GT. 1967. "The Subcellular Origin of Bioluminescence in Noctiluca miliaris". J Gen Physiol. 50 (5): 1429-58.

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Elbrächter, M. and Y. Z. Qi. 1998. "Aspects of Noctiluca (Dinophyceae) population dynamics." In: D.M. Anderson et al., Physiological Ecology of Harmful Algal Blooms. NATO ASI Series, Vol. G 41. Berlin: Springer-Verlag, pp. 315-335.

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Hausmann, Klaus; Hulsmann, Norbert; & Radek, Renate; "Protistology" (3rd Edition) 2003. in E. Scheizerbart’sche Verlagsbuchhandlung.

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Lenaers, Guy; Christopher Scholin, Yvonne Bhaud, Danielle Saint-Hilaire and Michel Herzog. 1991. "A molecular phylogeny of dinoflagellate protists (Pyrrhophyta) inferred from the sequence of 24S rRNA divergent domains D1 and D8." Journal of Molecular Evolution. Volume 32: 1; pp. 53-63

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Murray, Shauna; Marten Flø Jørgensen, Simon Y.W. Ho, David J. Patterson, and Lars S. Jermiin. 2005. "Improving the Analysis of Dinoflagellate Phylogeny based on rDNA." Protist. Vol. 156, 269-286

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Palmer, Jefferey D. 2003. "The Symbiotic Birth and Spread of Plastids: How Many Times and Whodunit?" J. Phycol. 39, 4-11

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Tada, Kuninao; Santiwat Pithakpol, Rumiko Yano and Shigeru Montani. 2000. "Carbon and nitrogen content of Noctiluca scintillans in the Seto Inland Sea, Japan." Journal of Plankton Research. Vol.22 no.6 pp.1203-1211

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Thomas Kiørboe and Josefin Titelman. 1998. "Feeding, prey selection and prey encounter mechanisms in the heterotrophic dinoflagellate Noctiluca scintillans." Journal of Plankton Research. V20: 8 pp. 1615-1636

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Umani, S. Fonda; A. Beran, S. Parlato, D. Virgilio, T. Zollet, A. De Olazabal, B. Lazzarini and M. Cabrini. 2004. "Noctiluca scintillans in the Northern Adriatic Sea: long-term dynamics, relationships with temperature and eutrophication, and role in the food web." Journal of Plankton Research. 26(5):545-561