Navigate:
Wells, M. L., University of Maine, Orono, USA, mlwells@maine.edu
Trick, C. G., University of Western Ontario, London, Canada, cyano@uwo.ca
Bill, B. D., NOAA Northwest Fisheries Science Center, Seattle, USA, brian.d.bill@noaa.gov
Cochlan, W. P., Romberg Tiburon Center for Environmental Studies, Tiburon, USA, cochlan@sfsu.edu
Trainer, V. L., NOAA Northwest Fisheries Science Center, Seattle, Seattle, USA, Vera.L.Trainer@noaa.gov
Pickell, L. P., University of Maine, Orono, USA, Lisa_Pickell@umit.maine.edu
IRON ENRICHMENT STIMULATES TOXIC DIATOM PRODUCTION IN THE HIGH NITRATE LOW CHLOROPHYLL EASTERN SUBARCTIC PACIFIC
Oceanic High-Nitrate, Low Chlorophyll (HNLC) environments have been targeted commercially for large-scale iron fertilizations to help mitigate global climate change. Adding iron to HNLC waters in bottle and mesoscale experiments consistently stimulates rapid growth of pennate diatoms of the genus Pseudo-nitzschia. While coastal Pseudo-nitzschia species often produce the neurotoxin domoic acid (DA), sometimes causing major ecosystem impacts, oceanic Pseudo-nitzschia species are believed to be non-toxic. We show that the post spring bloom diatom community at Ocean Station PAPA (50°N 145°W) produced up to 48 pg DA L-1 during multi-day sampling of the photic zone. Fresh isolates of P. cf. turgidula produced DA in deck-board incubations, and cell numbers and toxicity increased with nanomolar iron amendments; a finding supported by parallel deck-board continuous cultures experiments. Moreover, cell toxicity was increased further by co-additions of trace copper, indicating that low purity of iron substrates used in commercial fertilizations may generate unwanted ecosystem responses. Given the potential negative effects of DA in coastal food webs, these findings raise serious concern about the success and sustainability of large-scale iron fertilizations and their ecological consequences.
Session #:102
Date: 01-30-09
Time: 11:15
Presentation is given by student: No