1 research outputs found
A comparison of HPLC pigment analyses and biovolume estimates of phytoplankton groups in an oligotrophic lake.
11 páginas, 4 tablas, 4 figuras.Assessment of the contribution of distinct algal groups to phytoplankton biomass in oligotrophic lakes
by marker pigments is compared with assessment by cell-counting biovolume estimates. Seasonal
samples from an oligotrophic alpine lake (Redon, Pyrenees) mostly included species of chrysophytes,
dinoflagellates, cryptophytes and chlorophytes. The chlorophyl a (Chl a) corresponding to each algal
group was estimated using HPLC pigment analyses and the CHEMTAX program. Chl a
estimates and biovolume showed a significant correlation for all the groups during the ice-free
season except for chlorophytes. However, some of the samples from the initial phase of the ice cover
presented a clear departure from the relationship during the ice-free period in most groups. On the
other hand, the ratios between a specific marker pigment and the biovolume of the marked algal
group were significantly constant within the photic zone (>1% surface irradiance) for most of the
pigments and groups, including chlorophytes. Nevertheless, the ratios increased and showed a large
variability for samples below the photic depth or below the ice cover. The violaxanthin-chrysophyte
biovolume ratio presented an opposed tendency to other pigment-biovolume ratios, which increased in
inverse proportion to the depth of the sample. The results are discussed in terms of methodological
limitations, acclimation responses and species composition.This study was supported by the European Union (Contract
No. ENV4-CT95-007) within the framework of the
European Union Environment and Climate project
MOLAR (Measuring and modelling the Dynamic
Response of Remote Mountain Lake Ecosystems to Environmental
Change: a Program of Mountain Lake
Research).Peer reviewe