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| Témakiírás |
| | A biodiverzitás—ökoszisztéma-működés (BEF) kapcsolat globális trendjei folyóvízi fitoplanktonra
TÉMAKIÍRÁS
Intézmény: Eötvös Loránd Tudományegyetembiológiai tudományok
Biológia Doktori Iskola
témavezető: Abonyi András
helyszín (magyar oldal): ELKH Centre for Ecological Research, Institute of Aquatic Ecology (Budapest) helyszín rövidítés: ELTE
A kutatási téma leírása:
"Background
The biodiversity-ecosystem functioning (BEF) theorem suggests that biodiversity enhances community resource use efficiency (RUE) and ecosystem stability (see e.g. Loreau et al, 2001). The positive BEF relationship also holds true for microscopic phytoplankton in both natural (see e.g. Ptacnik et al. 2008; Duffy et al., 2017) and artificial assemblages (see e.g. Striebel et al., 2009; Stockenreiter et al., 2012; Schabhüttl et al. 2013). Amounting evidence from empirical datasets suggests that RUE is also enhanced by dominance (e.g. Filstrup et al. 2019; Crawford et al., 2021). Large river phytoplankton (microscopic algae living in suspension) is often dominated by centric diatoms well-adapted to turbulent and turbid conditions (Lack, 1971; Descy et al., 2012). The high dominance in large river phytoplankton may envisage disproportionate effects of dominance and diversity on ecosystem functioning. Since BEF has not been studied in large river phytoplankton so far, understanding long-term changes in diversity and related ecosystem functioning measures remains a key issue to predict the responses of large rivers to global environmental change at the ecosystem scale.
Large rivers are highly human-impacted, where global warming may further constrain ecosystem functioning at a long-term scale. W-European large rivers e.g. undergo substantial changes in response to altered hydrology and re-oligotrophication (Ibáñez & Peñuelas, 2019). A general pattern emerges showing the increasing dominance of macrophytes and the decreasing trend of phytoplankton biomass over time. Recent research also suggests a long-term quantitative decrease in phytoplankton and taxonomic richness in the middle Danube section (N-Budapest, Hungary; Abonyi et al., 2018). Water discharge shifted towards the more frequent occurrence of low-flow conditions. On the other hand, floods increased significantly in magnitude but decreased in duration with altered seasonality. Nutrients fuelling phytoplankton growth (N, P) as well as the total suspended solids decreased significantly, highlighting an altered underwater light climate. Water temperature increased significantly, especially in summer. In response, single-celled eutrophic centric diatoms decreased in relative abundance, but flagellated, elongated, and filamentous forms increased (Abonyi et al., 2018; Abonyi et al., 2020). A clear shift in phytoplankton composition was the dominance decrease of planktic taxa and the relative abundance increase of benthic diatoms. How resource use efficiency, as an ecosystem functioning measure, has been altered in response to long-term changes in diversity and community composition remains a question.
Expectations
The PhD student will analyse long-term changes in large river phytoplankton diversity, dominance, ecosystem functioning measures, as well as corresponding alterations in environmental variables. She/he will work to better understand whether and how diversity and dominance affect ecosystem functioning in river phytoplankton over time. She/he will build an extensive phytoplankton data set focusing on the River Danube phytoplankton but also including multiple large river data sets worldwide (e.g. River Loire, France; River Paraná, Brazil; River Pearl, China). Using the River Danube as a model system (at N-Budapest), the PhD student will also work on field data and experimental data. To this end, she/he will be involved in running a high-frequency phytoplankton monitoring of the middle Danube and run a regular laboratory experiment to understand diversity and dominance effects on different resource use efficiency measures (i.e. N, P, Si, light).
References
Abonyi, A., Ács, É., Hidas, A., Grigorszky, I., Várbíró, G., Borics, G., & Kiss, K. T. (2018). Functional diversity of phytoplankton highlights long‐term gradual regime shift in the middle section of the Danube River due to global warming, human impacts and oligotrophication. Freshwater Biology, 63(5), 456-472.
Abonyi, A., Kiss, K. T., Hidas, A., Borics, G., Várbíró, G., & Acs, E. (2020). Cell size decrease and altered size structure of phytoplankton constrain ecosystem functioning in the middle Danube River over multiple decades. Ecosystems, 23(6), 1254-1264.
Crawford, M. S., Barry, K. E., Clark, A. T., Farrior, C. E., Hines, J., Ladouceur, E., ... & Rüger, N. (2021). The function‐dominance correlation drives the direction and strength of biodiversity–ecosystem functioning relationships. Ecology Letters. DOI: 10.1111/ele.13776
Descy, J. P., Leitao, M., Everbecq, E., Smitz, J. S., & Deliège, J. F. (2012). Phytoplankton of the River Loire, France: a biodiversity and modelling study. Journal of plankton research, 34(2), 120-135.
Duffy, J. E., Godwin, C. M., & Cardinale, B. J. (2017). Biodiversity effects in the wild are common and as strong as key drivers of productivity. Nature, 549(7671), 261-264.
Filstrup, C.T., King, K.B.S. & McCullough, I.M. (2019). Evenness effects mask richness effects on ecosystem functioning at macro-scales in lakes. Ecology Letters, 22, 2120-2129
Ibáñez, C., & Peñuelas, J. (2019). Changing nutrients, changing rivers. Science, 365(6454), 637-638.
Lack, T. J. (1971). Quantitative studies on the phytoplankton of the Rivers Thames and Kennet at Reading. Freshwater Biology, 1(2), 213-224.
Loreau, M., Naeem, S., Inchausti, P., Bengtsson, J., Grime, J. P., Hector, A., Hooper, D. U., Huston, M. A., Raffaelli, D., Schmid, B., Tilman, D. & Wardle, D. A. (2001). Biodiversity and ecosystem functioning: current knowledge and future challenges. Science 294, 804–808
Ptacnik, R., Solimini, A.G., Andersen, T., Tamminen, T., Brettum, P., Lepisto, L. et al. (2008). Diversity predicts stability and resource use efficiency in natural phytoplankton communities. Proc. Natl. Acad. Sci. USA, 105, 5134–5138
Schabhüttl, S., Hingsamer, P., Weigelhofer, G., Hein, T., Weigert, A., & Striebel, M. (2013). Temperature and species richness effects in phytoplankton communities. Oecologia, 171(2), 527-536.
Stockenreiter, M., Graber, A. K., Haupt, F., & Stibor, H. (2012). The effect of species diversity on lipid production by micro-algal communities. Journal of applied phycology, 24(1), 45-54.
Tilman, D., Wedin, D. & Knops, J. (1996). Productivity and sustainability influenced by biodiversity in grassland ecosystems. Nature 379, 718–720."
előírt nyelvtudás: angol
további elvárások:
"Enthusiastic candidate with an MSc degree in Biology, Hydrobiology, Limnology, or related fields;
Phytoplankton identification skills (or wish to learn);
Excellent communication in English;
Large data management (or wish to learn);
R coding."
felvehető hallgatók száma: 2
Jelentkezési határidő: 2023-05-31 |
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