Morphology, phylogeny and PSP toxin composition of Alexandrium spp. isolated from Irish coastal waters

• Main Authors: Touzet, Nicolás, Paz, Beatriz, Riobó, Pilar, Franco, José Mariano, Raine, Robin
• Format: Book Part
• Language: English
• Published: Marine Institute 2006
• Subjects: Medio Marino; Centro Oceanográfico de Vigo; Northeast Atlantic
• Online Access: http://hdl.handle.net/10508/9926; http://hdl.handle.net/10261/321638

The dinoflagellate genus Alexandrium (Halim) has received considerable attention in recent years. In part, this has been due to recent taxonomic advances within the Dinophyceae. Many species from this genus however, produce paralytic shellfish poisoning (PSP) toxins that have had serious economic impacts within the aquaculture industry worldwide. The occurrence of PSP toxins in shellfish from the south coast of Ireland has been linked to the suspected presence of an Alexandrium population. This study describes what is currently understood of the distribution of Alexandrium spp. around Ireland, in terms of both species diversity and toxicity. Alexandrium cysts and vegetative cells were collected from sediment and water column samples from Irish coastal waters. These were used to establish a suite of mono-specific cultures. Morphological identification of the vegetative cells using the fluorescent stain Calcofluor White was confirmed by partial sequencing of amplified LSU rDNA. Toxicity testing showed that of all the species isolated only Alexandrium minutum from the south coast produced PSP toxins. This species had both a toxin profile (GTX-2 and GTX-3) and a distribution which confirmed that it has been responsible for historical occurrences of contamination of shellfish with PSP toxins.