Growth and phosphorus uptake by the toxic dinoflagellate Alexandrium catenella (dinophyceae) in response to phosphate limitation

Type Article
Date 2010-10
Language English
Author(s) Jauzein Cecile2, Labry Claire3, Youenou Agnes3, Quere Julien3, Delmas Daniel3, Collos Yves1
Affiliation(s) 1 : Univ Montpellier 2, CNRS, IFREMER, Lab Ecosyst Lagunaires,UMR 5119,IRD, F-34095 Montpellier 5, France.
2 : IFREMER, Lab LER LR, F-34203 Sete, France.
3 : IFREMER, Ctr Brest, Lab DYNECO Pelagos, F-29280 Plouzane, France.
Source Journal Of Phycology (0022-3646) (Wiley-blackwell Publishing, Inc), 2010-10 , Vol. 46 , N. 5 , P. 926-936
DOI 10.1111/j.1529-8817.2010.00878.x
WOS© Times Cited 22
Keyword(s) Alexandrium catenella, alkaline phosphatase, limitation, phosphorus, semicontinuous cultures
Abstract Alexandrium catenella (Whedon et Kof.) Balech has exhibited seasonal recurrent blooms in the Thau lagoon (South of France) since first reported in 1995. Its appearance followed a strong decrease (90%) in phosphate (PO(4)3-) concentrations in this environment over the 1970-1995 period. To determine if this dinoflagellate species has a competitive advantage in PO(4)3--limited conditions in terms of nutrient acquisition, semicontinuous cultures were carried out to characterize phosphorus (P) uptake by A. catenella cells along a P-limitation gradient using different dilution rates (DRs). Use of both inorganic and organic P was investigated from measurements of 33PO(4)3- uptake and alkaline phosphatase activity (APA), respectively. P status was estimated from cellular P and carbon contents (Q(P) and Q(C)). Shifts in trends of Q(P)/Q(C) and Q(P) per cell (Q(P center dot cell-1)) along the DR gradient allowed the definition of successive P-stress thresholds for A. catenella cells. The maximal uptake rate of 33PO(4)3- increased strongly with the decrease in DR and the decrease in Q(P)/Q(C), displaying physiological acclimations to PO(4)3- limitation. Concerning maximal APA per cell, the observation of an all-or-nothing pattern along the dilution gradient suggests that synthesis of AP was induced and maximized at the cellular scale as soon as PO(4)3- limitation set in. APA variations revealed that the synthesis of AP was repressed over a PO(4)3- threshold between 0.4 and 1 mu M. As lower PO(4)3- concentrations are regularly observed during A. catenella blooms in Thau lagoon, a significant portion of P uptake by A. catenella cells in the field may come from organic compounds.
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