''Akashiwo sanguinea'' is a species of marine

dinoflagellate The Dinoflagellates (), also called Dinophytes, are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered protists. Dinoflagellates are mostly marine plankton, but they are also commo ...

s well known for forming blooms that result in red tides. The organism is unarmored (naked). Therefore, it lacks a thick cellulose wall, the

theca In biology, a theca (: thecae) is a sheath or a covering. Botany In botany, the theca is related to plant's flower anatomy. The theca of an angiosperm consists of a pair of microsporangia that are adjacent to each other and share a common ar ...

, common in other genera of dinoflagellates. Reproduction of the

phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater Aquatic ecosystem, ecosystems. The name comes from the Greek language, Greek words (), meaning 'plant', and (), mea ...

species is primarily asexual. Recently recognized as

mixotrophic A mixotroph is an organism that uses a mix of different sources of energy and carbon, instead of having a single trophic mode, on the continuum from complete autotrophy to complete heterotrophy. It is estimated that mixotrophs comprise more than ...

, ''A. sanguinea'' is capable of preying on various organisms. For example, ''A. sanguinea'' is found to be capable of ingesting the cyanobacterium ''Synechococcus'' sp. at values comparable to other

heterotrophic A heterotroph (; ) is an organism that cannot produce its own food, instead taking nutrition from other sources of organic carbon, mainly plant or animal matter. In the food chain, heterotrophs are primary, secondary and tertiary consumers, but ...

phytoplankton. This suggests implications it may have on the grazing impact of ''

Synechococcus ''Synechococcus'' (from the Greek ''synechos'', in succession, and the Greek ''kokkos'', granule) is a unicellular cyanobacterium that is very widespread in the marine environment. Its size varies from 0.8 to 1.5 μm. The photosynthetic ...

''.

Description

Despite its lack of thecal plates, a prominent feature helpful in identifying armored flagellates, ''A. sanguinea'' is relatively large and easily recognizable. Like most dinoflagellates, one flagellum is complex, wrapping around the equator of the cell in a groove. The other flagellum extends out from the cell to help aid its movement through the water. ''A. sanguinea’s'' most prominent features are the lack of a nuclear envelope chamber and the apical groove's large, clockwise path when viewed from the front of the cell. These features, along with observations and data from LSU rDNA sequencing, recently helped declare a new genus for this species (Hansen & Moestrup).

Etymology

The genus name ''akashiwo'' is Japanese for

red tide A harmful algal bloom (HAB), or excessive algae growth, sometimes called a red tide in marine environments, is an algal bloom that causes negative impacts to other organisms by production of natural algae-produced toxins, water deoxygenation, ...

Distribution

''Akashiwo sanguinea'' covers a broad range of distributions. Frequent blooms exist off the coast of Florida and Southern California. Blooms dominated by this species have also been observed in Narragansett Bay, Rhode Island.

Behavior and physiology

''Akashiwo sanguinea'' exhibits a diurnal vertical migration pattern, observed to move toward the sun in field experiments even before the start of the light cycle. In laboratory settings, the migration is light dependent but the direction of movement is not solely explained by positive

phototaxis Phototaxis is a kind of taxis, or locomotory movement, that occurs when a whole organism moves towards or away from a stimulus of light. This is advantageous for phototrophic organisms as they can orient themselves most efficiently to receive ...

. It has also been shown to swim across large gradients in temperature. However, more study is needed to determine the organisms’ migratory behavior. ''Akashiwo sanguinea'' responds to certain changes in the water column by forming subsurface chlorophyll maximum layers in the marine environment. A study off of Southern California's coast observed a subsurface layer when nitrate was limiting to the organism. ''A. sangiunea's'' subsurface chlorophyll maximum layer has contributed to the success of larval anchovy growth on California's coastline. The larva have been observed to ingest this organism and not other species such as ''Chaetoceros'' spp. and ''Thalassiosira'' spp. suggesting a preference for ''A. sanguinea'' over other dinoflagellates.

Context and content

Synonyms ''

Gymnodinium ''Gymnodinium'' is a genus of dinoflagellates, a type of marine and freshwater plankton. It is one of the few naked dinoflagellates, or species lacking armor known as cellulosic plates. Since 2000, the species which had been considered to be part ...

splendens'' (Lebour), ''

sanguineum'' (Hirasaka), ''

nelsoni'' (Martin) The names listed above were used during prior research on the organism. The genus is now redefined into four new genera. ''Gymnodinium'' was one of many dinoflagellate genera declared when taxonomic nomenclature was limited to features only visible with the light microscope. In 2000, Hansen and Moestrup analyzed ultrastructural details of the organism using large-subunit (LSU) rDNA sequencing. Aided by this new technology, the scientists were able to declare variations in the path of the apical groove of the organism (found on the flagellar apparatus). Since the apical groove varies among species, the scientists used it to indicate differences between the unarmored flagellates. ''Akashiwo'' was one of four new genera that was redefined using the analysis.

HAB implications

''Akashiwo sanguinea'' has been correlated to

harmful algal bloom A harmful algal bloom (HAB), or excessive algae growth, sometimes called a red tide in marine environments, is an algal bloom that causes negative impacts to other organisms by production of natural algae-produced toxins, water deoxygenation, ...

s (HABs), but more study is needed to make sense of the blooms. The protist can produce

mycosporine-like amino acid Mycosporine-like amino acids (MAAs) are small secondary metabolites produced by organisms that live in environments with high volumes of sunlight, usually marine environments. The exact number of compounds within this class of natural products is y ...

s (MAAs) which are water-soluble

surfactants Surfactants are chemical compounds that decrease the surface tension or interfacial tension between two liquids, a liquid and a gas, or a liquid and a solid. The word ''surfactant'' is a blend of "surface-active agent", coined in 1950. As t ...

. A red tide caused by ''A. sanguinea'' was coincident with widespread seabird mortality across fourteen different species of birds in November–December 2007 in Northeastern Monterey Bay, California. Plankton samples showed ''A. sanguinea'' as the dominant flagellate in the bloom. Affected birds accumulated a proteinaceous material on their feathers, causing a loss in the natural water repellency. However no toxins, such as domoic acid, saxitoxin or brevetoxin was detected in the water. It was the first documented case of its tide causing harm to birds. In 2009 a huge foam event blamed on Akashiwo sanguinea killed vast quantities of sea birds from the northern Oregon coast to the tip of the Olympic Peninsula in Washington state. The species’ blooms have also been linked to

coral bleaching Coral bleaching is the process when corals become white due to loss of Symbiosis, symbiotic algae and Photosynthesis, photosynthetic pigments. This loss of pigment can be caused by various stressors, such as changes in water temperature, light, ...

. More research is needed before predictions of HAB events that may be linked with this species.