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Akashiwo sanguinea

Figure 1. General morphology of Akashiwo sanguinea. Adapted from Hulburt 1957.

SPECIES NAME: 
Akashiwo sanguinea (Hirasaka) Hansen et Moestrup

COMMON NAME:
Dinoflagellate

SYNONOMY:
Gymnodinum sanguineum Hirasaka
Gymnodinium splendens Lebour
Gymnodinium nelsoni Martin

This widespread dinoflagellate has appeared in the literature under several names as a species of Gymnodinium, but differs from that genus in several ultrastructural details that led Hansen and Moestrup (in Daugbjerg et al. 2000) to transfer the species to the new genus. Most of these ultrastructural details are typically not visible in the light microscope, except the large clockwise spiral of the apical groove (not shown here) can rarely be discerned. Hansen and Moestrup describe these features in detail and provide additional references.

SPECIES DESCRIPTION:
This species lives as single cells.  In cross section, the cell is ovoid with strong dorso-ventral compression. The dorsal side is convex and the ventral side is somewhat concave.  The cingulum is approximately median and slightly descending.  In ventral view (Figure 1) the epicone is bluntly rounded; the hypocone has two prominent posterior lobes and an incised sulcus.

The cell has a large number of elongate yellow or brown chloroplasts that radiate from the cell center (Figures 2, 3).  The nucleus is just above the cingulum in the epicone, and distinguishable in living cells by appearing as a clear area (Figures 1, 2). The trailing flagellum is quite long, often longer than the cell itself  (Figure 2).

Video. Live Akashiwo sanguinea. Click to pause, double-click to play.

Figure 4. Living A. sanguinea cell, 52 µm X 39 µm.

II.  HABITAT & DISTRIBUTION

HABITAT & REGIONAL OCCURENCE:
Akashiwo sanguinea is exclusively planktonic and has a worldwide distribution in temperate and tropical waters.  It is nearly always found in coastal and estuarine locations. 

INDIAN RIVER LAGOON DISTRIBUTION:
A. sanguinea is found throughout the IRL during most of the year, sometimes exceeding 105 cells per liter, although rare in the Mosquito Lagoon. Matsubara et al. (2007) characterize this species as eurythermal and euryhaline.

SIZE:
This is one of the largest dinoflagellates, with a length about 40-80 µm and a width of 30-50 µm.

III. LIFE HISTORY & POPULATION BIOLOGY

REPRODUCTION:
No reports were found on the sexual cycle of A. sanguinea.  In culture, several size morphologies are sometimes seen that may have reproductive significance or simply represent phenotypic variability.  Otherwise, vegetative cell division is the normal means of reproduction. Under some culture conditions, a mucoid cyst may be formed (Steidinger & Tangen 1997). There are nucleotide sequence data for over four dozen samples identified as A. sanguinea at http://www.ncbi.nlm.nih.gov/.

TROPHIC MODE:
According to Bockstahler & Coats (1993), A. sanguinea is mixotrophic, being primarily photosynthetic but also feeding on ciliate protozooplankton if necessary.  It is also susceptible to parasitic dinoflagellates such as Amoebophrya  (Coats & Park 2002), which may represent an unexplored means of population control in the IRL.

TOXICITY:
In general, this species is not considered to be toxic, and no toxicity or harmful activity has been verified in the IRL.  Reports of toxicity in A. sanguinea are mostly anecdotal and based on its abundance in natural populations in which mortality has occurred. However, toxicity of mice was reported by Tindall et al. (1984). Jessup et al. (2009) reported extensive seabird mortality caused by surfactant-like protein exudates derived from A. sanguinea, which coated their feathers and neutralized natural water repellency and insulation.

IV. REFERENCES

Bockstahler, KR & DW Coats. 1993. Spatial and temporal aspects of mixotrophy in Chesapeake Bay dinoflagellates. J. Eukaryot. Microbiol. 40: 49-60.

Coats, DW & MG Park. 2002. Parasitism of photosynthetic dinoflagellates by three strains of Amoebophrya (Dinophyta): parasite survival, infectivity, generation time, and host specificity.  J. Phycol. 38: 520-528.

Daugbjerg, N, Hansen, G, Larsen, J & Ø Moestrup. 2000. Phylogeny of some of the major genera of dinoflagellates based on ultrastructure and partial LSU rDNA sequence data, including the erection of three new genera of unarmoured dinoflagellates.  Phycologia 39: 302-317.

Hulburt, E. 1957. The taxonomy of unarmored Dinophyceae of shallow embayments on Cape Cod, Massachusetts.  Biol. Bull. 112: 196-219.

Jessup DA, Miller, MA, Ryan, JP, Nevins, HM, Kerkering, HA et al. 2009. Mass stranding of marine birds caused by a surfactant-producing red tide. PLoS ONE 4: e4550. doi:10.1371/journal.pone.0004550.

Matsubara, T, Nagasoe, S, Yamasaki, Y, Shikata, T & Y Shimasaki. 2007. Effect of temperature, salinity, and irradiance on the growth of the dinoflagellate Akashiwo sanguinea.  J. Exper. Mar. Biol. 342: 226-230.

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