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The dinoflagellates are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered protists. Dinoflagellates are mostly marine plankton, but they also are common in freshwater habitats. Their populations vary with sea surface temperature, salinity, and depth. Many dinoflagellates are photosynthetic, but a large fraction of these are in fact mixotrophic, combining photosynthesis with ingestion of prey.
Paralytic shellfish poisoning (PSP) is one of the four recognized syndromes of shellfish poisoning, which share some common features and are primarily associated with bivalve mollusks. These shellfish are filter feeders and accumulate neurotoxins, chiefly saxitoxin, produced by microscopic algae, such as dinoflagellates, diatoms, and cyanobacteria. Dinoflagellates of the genus Alexandrium are the most numerous and widespread saxitoxin producers and are responsible for PSP blooms in subarctic, temperate, and tropical locations. The majority of toxic blooms have been caused by the morphospecies Alexandrium catenella, Alexandrium tamarense, Gonyaulax catenella and Alexandrium fundyense, which together comprise the A. tamarense species complex. In Asia, PSP is mostly associated with the occurrence of the species Pyrodinium bahamense.
Dinocysts or dinoflagellate cysts are typically 15 to 100 µm in diameter and produced by around 15–20% of living dinoflagellates as a dormant, zygotic stage of their lifecycle, which can accumulate in the sediments as microfossils. Organic-walled dinocysts are often resistant and made out of dinosporin. There are also calcareous dinoflagellate cysts and siliceous dinoflagellate cysts.
A harmful algal bloom (HAB), or excessive algae growth, is an algal bloom that causes negative impacts to other organisms by production of natural algae-produced toxins, mechanical damage to other organisms, or by other means. HABs are sometimes defined as only those algal blooms that produce toxins, and sometimes as any algal bloom that can result in severely lower oxygen levels in natural waters, killing organisms in marine or fresh waters. Blooms can last from a few days to many months. After the bloom dies, the microbes that decompose the dead algae use up more of the oxygen, generating a "dead zone" which can cause fish die-offs. When these zones cover a large area for an extended period of time, neither fish nor plants are able to survive. Harmful algal blooms in marine environments are often called "red tides".
Alexandrium tamarense is a species of dinoflagellates known to produce saxitoxin, a neurotoxin which causes the human illness clinically known as paralytic shellfish poisoning (PSP). Multiple species of phytoplankton are known to produce saxitoxin, including at least 10 other species from the genus Alexandrium.
Karenia is a genus that consists of unicellular, photosynthetic, planktonic organisms found in marine environments. The genus currently consists of 12 described species. They are best known for their dense toxic algal blooms and red tides that cause considerable ecological and economical damage; some Karenia species cause severe animal mortality. One species, Karenia brevis, is known to cause respiratory distress and neurotoxic shellfish poisoning (NSP) in humans.
Dinophysis is a genus of dinoflagellates common in tropical, temperate, coastal and oceanic waters. It was first described in 1839 by Christian Gottfried Ehrenberg.
Gonyaulax is a genus of dinoflagellates with the type species Gonyaulax spinifera Diesing. Gonyaulax belongs to red dinoflagellates and commonly causes red tides. It can produce yesotoxins: for example, strains of Gonyaulax spinifera from New Zeland are yessotoxin producers.
Alexandrium is a genus of dinoflagellates. It contains some of the dinoflagellate species most harmful to humans, because it produces toxic harmful algal blooms (HAB) that cause paralytic shellfish poisoning (PSP) in humans. There are about 30 species of Alexandrium that form a clade, defined primarily on morphological characters in their thecal plates.
Alexandrium monilatum is a species of armored, photosynthetic, marine dinoflagellates. It produces toxins that, when present in high concentrations as "red tides", can kill fish and reduce growth rates of shellfish.
Pyrodinium was first discovered in 1906 in the waters around New Providence Island in the Bahamas. Pyrodinium is a monospecific species with two varieties, Pyrodinium bahamense var. compressum and Pyrodinium bahamanse var. bahamense. Pyrodinium is well known for producing Paralytic Shellfish Toxins (PSTs), e.g. saxitoxin, and the bioluminescence that lights up the bioluminescent bays in Puerto Rico and the Bahamas.
Alexandrium catenella is a species of dinoflagellates. It is among the group of Alexandrium species that produce toxins that cause paralytic shellfish poisoning, and is a cause of red tide. ‘’Alexandrium catenella’’ is observed in cold, coastal waters, generally at temperate latitudes. These organisms have been found in the west coast of North America, Japan, Australia, and parts of South Africa.
Polykrikos kofoidii is a species of phagotrophic marine pseudocolonial dinoflagellates that can capture and engulf other protist prey, including the toxic dinoflagellate, Alexandrium tamarense. P. kofoidii is of scientific interest due to its status as a predator of other dinoflagellates, a behavior that is significant in the control of algal blooms. It has a complex life cycle of both vegetative (asexual) and sexual reproduction complicated by its pseudocolonial structure.
Cochlodinium polykrikoides is a species of red tide producing marine dinoflagellates known for causing fish kills around the world, and well known for fish kills in marine waters of Southeast Asia. C. polykrikoides has a wide geographic range, including North America, Central America, Western India, Southwestern Europe and Eastern Asia. Single cells of this species are ovoidal in shape, 30-50μm in length and 25-30μm in width.
Gambierdiscus is a genus of marine dinoflagellates that produce ciguatoxins, a type of toxin that causes the foodborne illness known as ciguatera. They are usually epiphytic on macroalgae growing on coral reefs.
Dinoflagellates are eukaryotic plankton, existing in marine and freshwater environments. Previously, dinoflagellates had been grouped into two categories, phagotrophs and phototrophs. Mixotrophs, however include a combination of phagotrophy and phototrophy. Mixotrophic dinoflagellates are a sub-type of planktonic dinoflagellates and are part of the phylum Dinoflagellata. They are flagellated eukaryotes that combine photoautotrophy when light is available, and heterotrophy via phagocytosis. Dinoflagellates are one of the most diverse and numerous species of phytoplankton, second to diatoms.
Polykrikos is one of the genera of family Polykrikaceae that includes athecate pseudocolony-forming dinoflagellates. Polykrikos are characterized by a sophisticated ballistic apparatus, named the nematocyst-taeniocyst complex, which allows species to prey on a variety of organisms. Polykrikos have been found to regulate algal blooms as they feed on toxic dinoflagellates. However, there is also some data available on Polykrikos being toxic to fish.
Alexandrium ostenfeldii, also known as the sea fire, is a species of dinoflagellates. It is among the group of Alexandrium species that produce toxins causing paralytic shellfish poisoning. These organisms have been found in the Baltic Sea.
Coolia is a marine dinoflagellate genus in the family Ostreopsidaceae. It was first described by Meunier in 1919. There are currently seven identified species distributed globally in tropical and temperate coastal waters. Coolia is a benthic or epiphytic type dinoflagellate: it can be found adhered to sediment or other organisms but it is not limited to these substrates. It can also be found in a freely motile form in the water column. The life cycle of Coolia involves an asexual stage where the cell divides by binary fission and a sexual stage where cysts are produced. Some of the species, for example, Coolia tropicalis and Coolia malayensis, produce toxins that can potentially cause shellfish poisoning in humans.
Ana María Gayoso was an Argentine marine biologist, a specialist in study of marine phytoplankton, best known for being the first scientist to describe phytoplankton in the Bahía Blanca Estuary, and to initiate the sustained long-term oceanographic dataset in this ecosystem. She made significant contributions to the understanding of harmful algal blooms caused by toxic dinoflagellate species in the Patagonian gulfs, and was the first scientist to describe high abundances of the coccolithophore Emiliania huxleyi in the Argentine Sea, a key component in the primary productivity along the Patagonian Shelf Break front in the SW South Atlantic. She started the most extensive (1978-present) long-term database of phytoplankton and physico-chemical variables in South America, in a fixed monitoring site in the Bahía Blanca Estuary. She died on 28 December 2004 in Puerto Madryn.
References
- ↑ ANDERSON, D.M., KULIS, D.M., DOUCETTE, G.J., GALLAGHER, J.C. & BALECH, E. 1994 Biogeography of toxic dinoflagellates in the genus Alexandrium from the northeastern United States and Canada; Marine Biology, 120: 467-478.
- ↑ Martin, J.L., Page, F.H., Hanke, A., Strain, P.M., LeGresley, M.M., 2005. Alexandrium fundyense vertical distribution patterns during 1982, 2001 and 2002 in the offshore Bay of Fundy, eastern Canada. Deep-Sea Research Part II: Topicical Studies in Oceanography 52 (19–21), 2569–2592.
- ↑ Anderson, D.M., Kaoru, Y., White, A.W., 2000. Estimated annual economic impacts from harmful algal blooms (HABs) in the United States. Woods Hole Oceanographic Institution Technical Report. WHOI-2000-11. p. 97.
- ↑ HAYHOME, B.A., ANDERSON, D.M., KULIS, D.M. & WHITTEN, D.J. 1989 Variation among congeneric dinoflagellates from the northeastern United States and Canada. I. Enzyme electrophoresis; Marine Biology, 101: 427-435.
- ↑ SCHOLIN, C.A. & ANDERSON, D.M. 1994 Identification of group- and strain-specific genetic markers for globally distributed Alexandrium (Dinophyceae). I. RFLP analysis of SSU rRNA genes; Journal of Phycology, 30: 744-754.
- ↑ SCHOLIN, C.A., HERZOG, M., SOGIN, M. & ANDERSON, D.M. 1994 Identification of group- and strain-specific genetic markers for globally distributed Alexandrium (Dinophyceae). II. Sequence analysis of a fragment of the LSU rRNA gene; Journal of Phycology, 30: 991-1011.
- ↑ ANDERSON, D.M., KULIS, D.M., DOUCETTE, G.J., GALLAGHER, J.C. & BALECH, E. 1994 Biogeography of toxic dinoflagellates in the genus Alexandrium from the northeastern United States and Canada; Marine Biology, 120: 467-478.
- ↑ Lilly, E.L., Halanych, K.M., Anderson, D.M., 2007. Species boundaries and global biogeography of the Alexandrium tamarense complex (Dinophyceae). J. Phycol. 43 (6), 1329–1338.
- ↑ Miranda, Lilibeth N.; Zhuang, Yunyun; Zhang, Huan; Lin, Senjie (2012). "Phylogenetic analysis guided by intragenomic SSU rDNA polymorphism refines classification of Alexandrium tamarense species complex". Harmful Algae. 16: 35–48. doi:10.1016/j.hal.2012.01.002.
- ↑ Persson, A.; Smith, B.C.; Wikfors, G.H.; Quilliam, M. (2006). "Grazing on toxic Alexandrium fundyense resting cysts and vegetative cells by the eastern oyster (Crassostrea virginica)". Harmful Algae. 5 (6): 678–684. doi:10.1016/j.hal.2006.02.004.
- ↑ Anderson D. M., Stock C. A., Keafer B. A., et al. Alexandrium fundyense cyst dynamics in the Gulf of Maine. Deep-Sea Research Part II: Topicical Studies in Oceanography. 2005a;52:2522-2542.
- ↑ Erdner, DL; Richlen, M; McCauley, LAR; Anderson, DM (2011). "Diversity and Dynamics of a Widespread Bloom of the Toxic Dinoflagellate Alexandrium fundyense". PLOS ONE. 6 (7): e22965. Bibcode:2011PLoSO...622965E. doi: 10.1371/journal.pone.0022965 . PMC 3146535 . PMID 21829565.