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The relation between toxin production of Fibrocapsa japonica (Raphidophyceae) and available nitrate and phosphate

Tjallingii, F.J. (1998) The relation between toxin production of Fibrocapsa japonica (Raphidophyceae) and available nitrate and phosphate. Master's Thesis / Essay, Biology.

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Abstract

Changing nutrient conditions in the North Sea, have raised the question whether the species composition of the algae may be influenced in favor of potentially toxic species over non-toxic species. An understanding of the environmental factors influencing growth and toxin production is necessary before predictions on the occurrence of toxic algal blooms can be made and warnings of potential damage by can be issued. The nutrient physiology of the potentially harmful raphidophyte species Fibrocapsajaponica Tonumi et Takano was studied in relation to its production of toxins. Cultures were grown under different ratios of nitrate and phosphate. Cell numbers were determined and the concentration of phosphate and nitrate in the medium was measured. Growth was found to be faster under low nitrate concentrations and lower under phosphate limitation. The differences were however not significant except at the lowest phosphate concentration, where growth was significantly lower. Cultures grown in a low nitrate or phosphate medium had a shorter growth phase than control cultures (10-11 days in stead of 16 or more days). A possible effect of bacteria on growth was observed when comparing growth between trials. Toxin samples were analyzed by High Performance Liquid Chromatography (HPLC). The total toxin yield was highest when cultures declined and under limitation of phosphate. A shift was seen in the toxin profile during the culture period. Most measured components diminished towards the end of the culture period, but the first eluting component increased. A total of 8-9 components that are possibly toxic were identified, 3 or 4 of them new. Toxicity tests confirming their toxicity have not been performed yet.

Item Type: Thesis (Master's Thesis / Essay)
Degree programme: Biology
Thesis type: Master's Thesis / Essay
Language: English
Date Deposited: 15 Feb 2018 07:45
Last Modified: 15 Feb 2018 07:45
URI: http://fse.studenttheses.ub.rug.nl/id/eprint/9657

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