© 1998 by ICES/CIEM International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer
Effect of sampling frequency on detection of natural variability in phytoplankton: unattended high-frequency measurements on board ferries in the Baltic Sea
Finnish Institute of Marine Research PO Box 33, FIN-00931, Helsinki, Finland
Correspondence to E. Rantajärvi: tel. +358 9 613941, fax. +358 9 61394 494, e-mail: eija.rantajarvi{at}fimr.fi
This paper demonstrates the importance of adequate sampling frequency in both time and space when collecting data for the evaluation of regional differences and long-term trends in phytoplankton estimates. Variability in phytoplankton in the Baltic Sea has been recorded using automated flow-through analysers on board ferries with an average spatial and temporal resolution of 200 m and one day, respectively. Data collected in the Arkona Sea and in the Western Gulf of Finland during 1994 are used as examples. The analysis shows that changes in phytoplankton biomass may not be reliably detected when temporal and spatial sampling resolution is low. Because a fixed sampling station may not be representative of a sea area, a network of stations covering the entire basin with an interval of a few kilometres, or at least a transect over the area, has to be sampled. The appropriate resolution depends on the variability in Chl a concentrations. In the Arkona Sea, one weekly transect with a 1-km sampling interval is required during bloom periods when variability is highest, especially in spring, to reveal a 5% difference in the average Chl a concentrations between two different years at the 0.05 significance level. In summer, the resolution needed to detect a similar difference is one weekly transect with a 2.5 km sampling interval. Such high spatial and temporal sampling frequencies are difficult to obtain by traditional methods and the use of unattended recordings on board "ships-of-opportunity" may solve this problem.
Keywords: Baltic Sea, chlorophyll a variability, high-frequency measurements, phytoplankton monitoring, ships-of-opportunity
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  M. Thyssen, D. Mathieu, N. Garcia, and M. Denis Short-term variation of phytoplankton assemblages in Mediterranean coastal waters recorded with an automated submerged flow cytometer J. Plankton Res., September 1, 2008; 30(9): 1027 - 1040. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Thyssen, G. A. Tarran, M. V. Zubkov, R. J. Holland, G. Gregori, P. H. Burkill, and M. Denis The emergence of automated high-frequency flow cytometry: revealing temporal and spatial phytoplankton variability J. Plankton Res., March 1, 2008; 30(3): 333 - 343. [Abstract] [Full Text] [PDF]
|
|