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Nutrient limitation in two marine diatoms inhibits release of bromoform |
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| Authors: | M Nguvava B Kuyper E Bucciarelli H Waldron C Palmer |
| Affiliation: | 1. Department of Oceanography, University of Cape Town, Cape Town, South Africa;2. Current address: Department of Physical Sciences, Sokoine University of Agriculture, Tanzania;3. Current address: Department of Chemistry, University of the Western Cape, Cape Town;4. LMI ICEMASA, Université de Brest;5. CNRS, IRD, IFREMER, UMR 6539, LEMAR, OSU – IUEM, Plouzané, France;6. Applied Centre for Climate and Earth Systems Science, CSIR, Cape Town, South Africa |
| Abstract: | Bromoform released from phytoplankton and kelp in the ocean is the largest known carrier of bromine to the atmosphere. The photoproducts of atmospheric bromoform catalyse ozone depletion. Laboratory investigations were conducted into the link between nutrient limitation and bromoform production using axenic cultures of two warm-water diatoms (Chaetoceros neogracile and Phaeodactylum tricornutum). During exponential growth the bromoform production was 2 000–3 000 nmol bromoform (g Chl a)?1 h?1, i.e. 10–100 times higher than earlier values for temperate and cold-water diatoms. Bromoform production decreased down to zero under CO2 and nitrate limitation for both species. These results suggest that the bromoform production could be directly related to bromoperoxidase activity (and irradiance) only during exponential growth, whereas compounds other than bromoform might be formed under nutrient limitation. |
| Keywords: | carbon dioxide limitation Chaetoceros neogracile nitrate limitation Phaeodactylum tricornutum |