FTIR spectroscopy as molecular fingerprint has been used to assess macromolecular and ele-mental stoichiometry as well as growth rates of phytoplankton cells. Chemometric models have been developed to extract quantitative information from FTIR spectra to reveal macro-molecular composition (of proteins, carbohydrates and lipids), C:N ratio, and growth potential. In this study, we tested these chemometric models based on lab-cultured algal species in mon-itoring changes of phytoplankton community structure in a hypertrophic lake (Lake Auensee, Leipzig, Germany), where a seasonal succession of spring green algal bloom followed by cya-nobacterial dominance in summer can be commonly observed. Our results demonstrated that green algae reacted to environmental changes such as nitrogen limitation (due to imbalanced nitrogen and phosphorus supply) with restricted growth by changing carbon allocation from protein synthesis to storage carbohydrates and/or lipids, and increased C:N ratio. By contrast, cyanobacteria proliferated under nitrogen limiting conditions. Furthermore, the FTIR-based growth potential of green alga matched well with the population biomass determined by the Chl-a concentration. However, the predicted growth potential based on FTIR spectroscopy cannot describe the realistic growth development of cyanobacteria in this lake. These results revealed that green algae and cyanobacteria have different strategies of C-allocation stoichi-ometry and growth patterns in response to environmental changes. These taxon-specific re-sponses may explain at a molecular level why green algae bloomed in the spring under condi-tions with sufficient nutrient, lower pH and lower water temperature; while cyanobacteria overgrew green algae and dominated in the summer under conditions with limited nutrient availability, higher pH and higher water temperature. In addition, the applicability of these chemometric models for predicting field cyanobacterial growth is of limited value. This may be attributed to other special adaptation properties of cyanobacterial species under stress growth conditions. We used flow cytometry to isolate functional algal groups from the water samples. Despite some drawbacks of the flow cytometry combined FTIR spectroscopy tech-nique, this method provides prospects of monitoring water quality and early warning of harmful algal blooms.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:36091 |
| Date | 13 November 2019 |
| Creators | Liu, Zhixin |
| Contributors | Universität Leipzig |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
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