FN Archimer Export Format
PT J
TI Oligotrophication and emergence of picocyanobacteria and a toxic dinoflagellate in Thau lagoon, southern France
BT 
AF COLLOS, Yves
   BEC, Beatrice
   JAUZEIN, Cecile
   ABADIE, Eric
   LAUGIER, Thierry
   LAUTIER, Jacques
   PASTOUREAUD, Annie
   SOUCHU, Philippe
   VAQUER, Andre
AS 1:1;2:1;3:1,2;4:2;5:2;6:1;7:2;8:2;9:1;
FF 1:;2:PDG-DOP-LER-LERAR;3:PDG-DOP-LER-LERLR;4:PDG-DOP-LER-LERLR;5:PDG-DOP-LER-LERLR;6:;7:PDG-DOP-LER-LERLR;8:PDG-DOP-LER-LERMPL;9:;
C1 Univ Montpellier 2, CNRS, IFREMER, UMR Ecosyst Lagunaires 5119, F-34095 Montpellier 5, France.
   Inst Francais Rech Exploitat Mer, Lab Environm Ressources LR, F-34203 Sete, France.
C2 UNIV MONTPELLIER, FRANCE
   IFREMER, FRANCE
SI ARCACHON
   SETE
   NANTES
SE PDG-DOP-LER-LERAR
   PDG-DOP-LER-LERLR
   PDG-DOP-LER-LERMPL
IN WOS Ifremer jusqu'en 2018
   copubli-france
   copubli-univ-france
IF 1.803
TC 85
UR https://archimer.ifremer.fr/doc/2009/publication-6420.pdf
LA English
DT Article
DE ;Skeletonema costatum;Alexandrium catenella;Picocyanobacteria;Oligotrophication;Long term variability;Thau lagoon
AB Time series data have been examined in Thau lagoon (Southern France) from 1972 to 2006 for water temperature, salinity, nutrients and from 1987 to 2006 for phytoplankton. A first main trend identified is an increase in mean annual water temperature (1.5 degrees C over 33 years or 0.045 degrees C/year) that was not evenly distributed among seasons. The highest rate of increase was in the spring (+ 3.0 degrees C over 33 years), followed by summer (+ 2.0 degrees C and fall (+ 1.7 degrees C. In winter, no significant increase over the 33 year period could be found. A second clear trend is a large decrease in soluble reactive phosphorus (SRP) concentration over the same 33 year period (summer values decreased from 10 mu M to 1 mu M. while winter values decreased from 3 mu M to undetectable at present). Nitrate concentrations depended mainly on rainfall events and watershed runoff. Ammonium data were too fragmentary to be useful. N/P ratios expressed the traditional way of DIN/SRP cannot be used for phytoplankton that are not strict autotrophs. The recent and almost simultaneous appearance of both picocyanobacteria (mostly Synechococcus) and the toxic dinoflagellate Alexandrium catenella in Thau seem to be related to reduced nutrient loading and the increase in water temperature. A. catenella blooms occur either in the spring or the fall when water temperature is near 20 degrees C and remains so for several weeks with winds speeds below 2-3 m s(-1). Picocyanobacterial growth is stimulated by increased summer temperatures, and lowered SRP levels provide picocyanobacteria an ecological advantage over other phytoplankton classes, in particular diatoms such as Skeletonema costatum whose cell densities have decreased over the last 8 years in summer and fall, but not in winter. An hypothesis is presented according to which A. catenella is not stimulated by increased temperatures, but is able to use picocyanobacteria for growth, and this provides this organism an additional resource over other strictly autotrophic phytoplankton. On a more general level, our data do not support the hypothesis that increased nutrient loading leads to harmful blooms of dinoflagellates. Instead, a combination of habitat disturbance and species displacement seems to lead to such blooms. (C) 2008 Elsevier B.V. All rights reserved.
PY 2009
SO Journal of Sea Research
SN 1385-1101
PU Elsevier
VL 61
IS 1-2
UT 000263197000009
BP 68
EP 75
DI 10.1016/j.seares.2008.05.008
ID 6420
ER

EF