Gambierdiscus Belizeanus

''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.

Morphology

''Gambierdiscus'' cells generally have a lenticular shape with a depression on the ventral side of the cell, from where the two dissimilar flagella arise. ''Gambierdiscus'' cells have an orange to brown colour due to the assessory pigments peridinin, diadinoxanthin and dinoxanthin.

Distribution

The marine dinoflagellate genus ''Gambierdiscus'' occurs globally in tropic and subtropic regions. It mainly grows attached to macroalgae and coralline turfalgae. Thus, it does not form visible surface blooms like many other harmful dinoflagellate species (red tides). A decrease in coral reefs due to bleaching, pollution or overfishing usually facilitates the growth of macroalgae, which can cause spreading of this epiphytic dinoflagellate genus.

Ciguatera

Several ''Gambierdicus'' species produce potent toxin such as ciguatoxin and maitotoxin, which cause ciguatera fish poisoning. Humans often consume the toxins, as herbivorous fish, which feed on macroalgae, ingest the dinoflagellates. Afterwards, carnivorous fish, which are targeted by fishing industries, move the toxins further up the food chain. Ciguatera is the most common form of seafood poisoning caused by harmful algal blooms in the world and its incidence and range appear to spread. Best estimates indicate that more than 50,000 people are globally affected every year. Currently, ''G. polynesiensis, G. excentricus'' and ''G. silvae'' are recognized as being highly toxic, but ongoing and future research might identify more toxic metabolites in other species.

Predictions of ciguatera outbreaks are very challenging, as toxin profiles differ a lot between different species. Additionally, our knowledge about the species diversity of ''Gambierdiscus'' is limited and the number of described ''Gambierdiscus'' species increases every year. Furthermore, toxin production of each species varies significantly over time and space due to changes in environmental conditions like nutrient concentrations and sea surface temperature. An increase in sea surface temperature in the future might cause spreading of ''Gambierdiscus'' species further towards the poles and result in more cases of ciguatera fish poisoning.

Evolution and systematics

Species

The genus ''Gambierdiscus'' contains the following 12 species:

* '' Gambierdiscus australes'' Chinian & M.A.Faust
* '' Gambierdiscus belizeanus'' Faust
* '' Gambierdiscus caribaeus'' Vandersea et al.
* '' Gambierdiscus carolinianus'' Litaker et al.
* '' Gambierdiscus carpenteri'' Kibler et al.
* '' Gambierdiscus lapillus'' Kretzschmar, Hoppenrath & Murray
* ''Gambierdiscus pacificus'' Chinain & Faust
* ''Gambierdiscus polynesiensis'' Chinain & Faust
* '' Gambierdiscus ruetzleri'' Faust et al.
* '' Gambierdiscus silvae'' S. Fraga & F. Rodríguez
* ''Gambierdiscus toxicus'' Adachi & Fukuyo
* '' Gambierdiscus yasumotoi'' Holmes

Phylogeny

The following cladograms illustrate the internal relationships between the ''Gambierdiscus'' species as analyzed in 2014, through a phylogenetic analysis using different regions of the large ribosomal subunit or LSUrRNA.

References

{{Taxonbar, from=Q18601090

Dinoflagellate genera
Gonyaulacales