JPR Advance Access published online on August 7, 2008
Journal of Plankton Research, doi:10.1093/plankt/fbn084
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Effects of Lugol's fixation on the size structure of natural nano-microplankton samples, analyzed by means of an automatic counting method
1 Marine Research Division, AZTI Foundation, Txatxarramendi Ugartea, z/g 48395, Sukarrieta (Bizkaia), Spain 2 Marine Research Division, AZTI Foundation, Herrera Kaia Portualdea, z/g 20110, Pasaia (Guipuzkoa), Spain
* CORRESPONDING AUTHOR: lzarauz{at}suk.azt.es
Received on November 21, 2007; revised on July 31, 2008; accepted on August 4, 2008
| Abstract |
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Accurate abundance and biomass measurements are essential steps towards determining the role of nano-microplankton in the microbial food web. Due to practical constraints, traditional microscope analysis of nano-microplankton requires preservation; but preservatives alter plankton samples and bias the measurements. The majority of studies on the effects of preservation have been based on cell cultures. However, new automatic counting systems offer the possibility to investigate the effect of fixatives on large numbers of natural samples. In the present study, cell counts of live and 1% Lugol's preserved samples were compared at 115 stations located in the Bay of Biscay. Additionally, the effect of different Lugol's concentration (1% and 5%) was studied. Analyses were performed with the FlowCAM (Sieracki et al., 1998), using plankton samples directly collected from the field. The results show that the analysis of natural samples preserved with a single fixative biases the abundance and biomass estimates of different size ranges of the nano and microplankton, not only in the large sizes. This is due to changes in cell abundance, especially in the nanoplankton size range and to the formation of aggregates.
Key Words: Lugol's solution nano-microplankton image analysis FlowCAM
Communicating Editor: Dr Roger Harris