Presentation on theme: "Algal toxins in Scottish waters: the first association of domoic acid with the diatom Pseudo-nitzschia pseudodelicatissima complex in the North East of."— Presentation transcript:
Algal toxins in Scottish waters: the first association of domoic acid with the diatom Pseudo-nitzschia pseudodelicatissima complex in the North East of Scotland Eileen Bresnan, Jean-Pierre Lacaze, Sheila Fraser, Lyndsay Brown, Ana-Luisa Amorim and Kathryn Cook Marine Scotland Science, Marine Laboratory, 375 Victoria Road, Aberdeen AB11 9DB Introduction Diatom genus Pseudo-nitzschia (Peragallo) Routinely observed in Scottish waters Two species within genus (P. australis and P. seriata) confirmed as producers of domoic acid (DA) 1 DA toxin responsible for amnesic shellfish poisoning High concentrations of DA closed offshore scallop fisheries from 1998 – DA detected in faeces and urine of seals along the east coast of Scotland – Study at Stonehaven ecosystem monitoring site considered if zooplankton could act as a vector for DA in Scottish waters Light microscopy (LM) cannot identify Pseudo- nitzschia cells to species level LM can only separate cells into two different size classes ( 5µm diameter) Electron microscopy or molecular methods required to confirm identification How to identify Pseudo-nitzschia? P. seriata P. australis Light micrograph of Pseudo-nitzschia cells Transmission electron micrograph of Pseudo-nitzschia cells Enlarged central portions of Pseudo-nitzschia cells
Algal toxins in Scottish waters: the first association of domoic acid with the diatom Pseudo-nitzschia pseudodelicatissima complex in the North East of Scotland Study site Stonehaven monitoring site is sampled weekly since 1997 Temperature, salinity, nutrients and plankton measured Calanus was sampled during 2008 for DA analysis Liquid chromatography – mass spectrometry – mass spectrometry (LC-MS-MS) was used Toxin data DA does accumulate in copepods at Stonehaven A maximum concentration of 11 ρg DA. copepod -1 was recorded in July Diversity of the Pseudo-nitzschia bloom during July was examined The copepod Calanus Pseudo-nitzschia cells counts and DA concentrations in Calanus at the Stonehaven monitoring site in 2008.
Algal toxins in Scottish waters: the first association of domoic acid with the diatom Pseudo-nitzschia pseudodelicatissima complex in the North East of Scotland Morphological measurements Whole Pseudo-nitzschia cell Poroids Central Interspace (CI) Fibulae Striae LengthWidth CIFibulaeStriaePoroids (µm)(µm)(in 10µm)(in 10µm)(in 1µm ) – 1.5 Y – Structure of Pseudo-nitzschia cells from July bloomIdentification of Pseudo-nitzschia cells A JEOL JEM 1400 Plus TEM was used to examine cells Morphological structures on Pseudo-nitzschia were measured Cells were identified as the recently described Pseudo-nitzschia plurisecta 3 This is a species within the P. pseudodelicatissima species complex Blooms of this species were previously observed in Scottish waters following an extensive Karenia mikimotoi bloom. This is the first association of this species with DA accumulation in Scottish waters Acknowledgements The authors would like to thank Mr. Kevin McKenzie at the Electron Microscopy Unit, Institute of Medical Sciences, University of Aberdeen for his assistance. This project was funded as part of the Scottish Government’s schedule of service ST03p and ROAME AE1198. References 1 Fehling J., Green D., Davidson K., Bolch C. and Bates S. (2004) J. Phycol., 40, 622 – Hall A. and Frame E. (2010), Harmful Algae, 9, 489 – Orive E., David H. and Miguel I. (2013), J. Phycol. 49,