G. Gregori et al., Phytoplankton group dynamics in the Bay of Marseilles during a 2-year survey based on analytical flow cytometry, CYTOMETRY, 44(3), 2001, pp. 247-256
Background: The Bay of Marseilles is under the influence of a large urban c
oncentration and its maritime activities. All of them discharge compounds (
hydrocarbons, excess nutrients, heavy metals, chemicals, etc.) that can alt
er the marine ecosystem. To investigate whether ultra-phytoplankton (< 10 m
um) could be used as biosensors for their own ecosystem, a 2-year survey wa
s conducted in the Bay of Marseilles.
Methods: Seven stations monitored water mass and potential anthropic effect
s in the bay. Seawater samples were collected monthly or bimonthly at three
depths, prefiltered, fixed, and kept in liquid nitrogen until flow cytomet
ric analysis.
Results: Five categories were created: Prochlorococcus, picoeukaryotes (<2
mum), nanoeukaryotes I (2-6 mum), nanoeukaryotes II (6-10 mum), and Synecho
coccus (<1.5 mum). Artificial neural network analysis (Kohonen self-organiz
ing maps) produced the same number of clusters as cluster analysis with Win
list software (Verity Software House).
Conclusions: In addition to the wide variabilities in abundance and biomass
, there were a strong seasonal signal and sporadic events. Lessons are deri
ved from this study for future monitoring of marine microorganisms. (C) 200
1 Wiley Liss, Inc.