Aquatic Sciences Meeting, Albuquerque 2001

SS16 Iron Bioavailability and Limitation to Primary Production (Disciplinary Connections)

Date: Monday, February 12, 2001, Time: 2:30:00 PM

Location: Mesilla

Wells, M, L, University of Maine, Orono, USA, mlwells@maine.edu

Maldonado, M, T, University of Maine, Orono, USA, maria.maldonado@maine.edu

Trick, C, G, University of Western Ontario, London, USA, cyano@julian.uwo.ca

IRON AVAILABILTY AND THE TOXICITY OF PSEUDO-NITZSCHIA SPP.: RESULTS FROM MONOCLONAL AND NATURAL POPULATION CULTURES DURING THE 1998 MONTEREY BAY BLOOM

Production of domoic acid (DA) by toxigenic Pseudo-nitzschia spp. not only can cause amnesic shellfish poisoning in humans but also can dramatically affect marine ecosystems. It has been shown that DA forms stable complexes with Fe and Cu in seawater, suggesting its production may be related to trace metal stress. On-deck incubation studies during the 1998 Monterey Bay Pseudo-nitzschia australis bloom showed that small additions of desferrioxamine B (DFB) curtailed Fe uptake more sharply in bloom waters than at adjacent coastal sites. This finding is consistent with laboratory results showing that toxigenic P. multiseries has a uniquely poor ability to sequester inorganic Fe compared to other diatoms. However, Fe stress stimulates the extracellular release of DA, which significantly enhances Fe uptake rates. Indeed, Fe stress induced by DFB additions to on-deck incubations from the 1998 bloom event caused a dramatic decrease in intracellular DA concentrations, presumably due to its release. These findings suggest that the variable particulate DA concentrations of toxigenic Pseudo-nitzschia bloom events may be related to Fe availability, with high intracellular DA concentrations occurring only under Fe-replete conditions.

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Aquatic Sciences Meeting, Albuquerque 2001

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