“Canary Islands (NE Atlantic) as a biodiversity ‘hotspot’ of Gambierdiscus: Implications for future trends of ciguatera in the area”

Abstract

In the present study the geographical distribution, abundance and composition of Gambierdiscus was described over a 600km longitudinal scale in the Canary Islands. Samples for cell counts, isolation and identification of Gambierdiscus were obtained from five islands (El Hierro, Tenerife, Gran Canaria, Fuerteventura and Lanzarote). Average densities of Gambierdiscus spp. between 0 and 2200cellsg blot dry weight of macrophyte were recorded. Morphological (light microscopy and SEM techniques) and molecular analyses (LSU and SSU rDNA sequencing of cultures and single cells from the field) of Gambierdiscus was performed. Five Gambierdiscus species (G. australes, G. caribaeus, G. carolinianus, G. excentricus and G. silvae), together with a new putative species (Gambierdiscus ribotype 3) were identified. These results suggest that some cases of CFP in the region could be associated with the accumulation of ciguatoxins in the marine food web acquired from local populations of Gambierdiscus. This unexpected high diversity of Gambierdiscus species in an area which a priori is not under risk of ciguatera, hints at an ancient settlement of Gambierdiscus populations, likely favored by warmer climate conditions in the Miocene Epoch (when oldest current Canary Islands were created), in contrast with cooler present ones. Currently, warming trends associated with climate change could contribute to extend favorable environmental conditions in the area for Gambierdiscus growth especially during winter months.

Toxicity Characterisation of Gambierdiscus Species from the Canary Islands

“…In summary, our findings clearly show differences in the toxicities of different microalgal species and in the distribution of Gambierdiscus species between islands of the Canary Islands [22]. Moreover, the differing toxicities of different strains of the same species highlight the need to assess intraspecific and geographic variations in the distribution of CTX and MTX toxicity.…”

“…Two additional episodes happened in 2008 causing the intoxication of 11 people [20]. Since then, several CFP episodes affected 113 people (Canary Government, 2017), [21,22]. Because of recurrent outbreaks, CFP has been designated as a notifiable disease in the Canary Islands since 2015 (Canary Government, 2017).…”

Morphological and molecular phylogenetic identification and record verification of Gambierdiscus excentricus (Dinophyceae) from Madeira Island (NE Atlantic Ocean)

“…The G. excentricus strain tested in the (Litaker et al, 2017) study was~44-to 1,740-fold more toxic than the other examined species. G. excentricus is present and abundant in the eastern Atlantic (Canary Islands; Fraga et al, 2011;Rodríguez et al, 2017), and has been found in Brazil (Nascimento et al, 2015) and in the Caribbean Sea (Litaker et al, 2017). Therefore, we suggest that this species may be likely to be the causative species for the production of CTX toxins related to CFP poisoning cases in Madeira.…”

Scaling Up From Regional Case Studies to a Global Harmful Algal Bloom Observing System

“…Recent improvements in sampling, taxonomic characterization, and sophisticated toxin detection indicate that CFP-producing species may be spreading from tropical to temperate latitudes due to global warming (Tester et al, 2010;Laza-Martínez et al, 2016;Rodríguez et al, 2017;Nishimura et al, 2018). Phenological changes may also be occurring in CFP-prevalent areas such as the Caribbean Sea (Tosteson, 2004;Nakada et al, 2018).…”