Impacts of eutrophication and climate change on phytoplankton community structure, size diversity, and phytoplankton based ecological status

Erdoğan, Şeyda
The aim of this thesis is to investigate the effects of climate change and eutrophication on phytoplankton; community structure, mean size, mean variance in size and water quality with two main approaches: i) Space-for-time substitute approach by using snap-shot sampling in 47 from 42 N to 32 N latitude of Turkey. ii) Mesocosm experiment through latitudinal gradient in six countries (Sweden, Estonia, Germany, Czech Republic, Greece and Turkey) using nutrient temperature and depth as main parameters. Mean phytoplankton size and variance in size structure was mainly regulated by top down control (zooplanktivorous fish and zooplankton) however nutrient also has indirect effect via regulating fish and zooplankton community composition. Especially rotifer species has positive significant effect on mean phytoplankton size increase probably due to their selective grazing on small size phytoplankton species. Mesocosm experiment results showed that phytoplankton biovolume increase mainly driven by temperature and nutrient increase. Moreover, cyanobacteria contribution also increased with nutrient and temperature interaction. While severe water level decrease leads to macrophyte death, low water level decrease promoted macrophye growth and suppressed phytoplankton increase likely due to nutrient competition and allelopathic effects. Phytoplankton quality indice that was developed for Mediterranean reservoirs seem practicable for Turkish reservoirs. However, for the shallow lake ecosystems applied indice results showed high variability, to develop a reliable phytoplankton indice Turkey should start regular monitoring studies, based on national typologies and data a national phytoplankton indice should be developed.  


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Citation Formats
Ş. Erdoğan, “Impacts of eutrophication and climate change on phytoplankton community structure, size diversity, and phytoplankton based ecological status,” Ph.D. - Doctoral Program, Middle East Technical University, 2016.