''Karenia mikimotoi'' is a
dinoflagellate
The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...
species from the genus ''
Karenia''. Its first appearance was in Japan in 1935 and since then, it has appeared in other parts of the world such as the east coast of the United States, Norway, and the English Channel.
Description
''Karenia mikimotoi'' has yellow-brown
chloroplast
A chloroplast () is a type of membrane-bound organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. The photosynthetic pigment chlorophyll captures the energy from sunlight, converts it, and stores it in ...
s and, like other species in its genus, is able to activate photosynthetically. It lacks thecal plates, and is more ovular.
Blooms usually form during warmer months.
The toxicity of ''Karenia mikimotoi'' is not fully understood, whereas other species in ''Karenia'' have identified toxins that are shown to kill marine life. For example, ''
Karenia brevis'' has brevetoxins. It is believed that its killing effects are due to a combination of the creation of an anoxic environment by the physical bloom itself in addition to some sort of toxin.
New toxins called
gymnocin A and B were recently discovered,
[Silke, J., et al]
''Karenia mikimotoi'': An exceptional dinoflagellate bloom in western Irish waters, summer 2005.
Marine Institute. Marine Environment and Food Safety Services, Galway. November, 2005. Accessed 9 May 2013. but their low toxicity is inconsistent with the high number of deaths ''Karenia mikimotoi'' causes. It is believed that in
red tide
A harmful algal bloom (HAB) (or excessive algae growth) is an algal bloom that causes negative impacts to other organisms by production of natural phycotoxin, algae-produced toxins, mechanical damage to other organisms, or by other means. HABs are ...
s, ''Karenia mikimotoi'' fills in the fish’s gills, thereby allowing direct contact with toxins. This is a more likely approach to the toxin’s mechanisms.
Major appearances
In August, 1978, a bloom stretched 100 km eastwards in
Roaringwater Bay from Fastnet Rock to Kinsale Harbor in Irish waters. The next year at around the same time, a similar bloom appeared, and again in 1984. These blooms resulted in the deaths of
benthic
The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...
organisms as well as farmed culture and their consistency suggests the water zone between the upwelling open ocean and the more stratified inner bay might be favorable conditions for phytoplankton growth.
[
The English Channel experienced a major bloom in 2003 that traveled from the western English Channel at end of June to the French coast of Brittany at the beginning of August. The density of this bloom was up to 100 mg/m3 whereas it usually only takes 10 mg/m3 to cause noticeable discoloration.
In 2005, a major bloom appeared off the west coast of Ireland. Deaths due to the bloom persisted throughout that entire summer. In August, deaths were still being reported. There were reports of dead ]lugworm
The lugworm or sandworm (''Arenicola marina'') is a large marine worm of the phylum Annelida. Its coiled castings are a familiar sight on a beach at low tide but the animal itself is rarely seen except by those who, from curiosity or to use as f ...
s and cockles washing up on beaches, as well as unoxygenated sediment beginning to appear due to eliminations in other parts of the ecosystem.DEFRA DEFRA may refer to:
* Deficit Reduction Act of 1984, United States law
* Department for Environment, Food and Rural Affairs, United Kingdom government department
{{Disambiguation ...
, the UK government department responsible for environmental protection, blamed mass deaths of crabs and lobsters along the coast of north-east England between October 2021 and February 2022 on blooms of ''Karenia mikimotoi'', but this is disputed by local commercial fisheries, who point out that blooms are unlikely as the water temperature, at 13°C, is too cold. Instead, it is speculated that the polluting chemical pyridine
Pyridine is a basic heterocyclic organic compound with the chemical formula . It is structurally related to benzene, with one methine group replaced by a nitrogen atom. It is a highly flammable, weakly alkaline, water-miscible liquid with a d ...
is responsible.
Further reading
References
{{Taxonbar, from=Q16983874
Gymnodiniales