Climate Impact on Freshwater Biodiversity: General Patterns in Extreme Environments of North-Eastern Siberia (Russia)

Aims: The aims of the current study are to reveal the response of high latitude riverine planktonic algal communities in northeastern Siberia to extreme climatic conditions of its habitats.
Study Design: We implemented diverse statistical methods, which represent some new approaches in freshwater algal diversity analysis.
Place and Duration of Study: Institute of Evolution, University of Haifa, Israel, Institute for Biological Problems of Cryolithozone SB RAS, Russia, between June 2008 and January 2014.
Methodology: We collected 800 samples of phytoplankton from 400 sites of 12 northeastern Siberian rivers in gradients of climatic and chemical variables that we analyzed. New indices - Geo-associated and Dynamic Habitat Index were included in this analysis. Statistical methods for comparative floristic analyses were used for calculating the similarity of algal communities among the sampling stations. Multiple regression stepwise statistical analysis on phytoplankton including chemical and climatic variables data was performed. Species diversity in algal communities and their environmental variables relationships were calculated.
Results: As a result, 1283 species (1637 taxa of species and infraspecies) from six taxonomic divisions were identified in phytoplankton communities. Species richness as a whole increased to the north. Abundance and biomass were highly correlated. Two types of phytoplankton communities were identified: a southern community with increasing diatoms and a northern group with decreasing diatoms to the north. Diatoms prevailed but were replaced by green algae in high mountains or by green and Chrysophyta algae and Cyanobacteria in the Arctic. We revealed major variables that considered stimulating or stress factors with helps of statistical prorgams.
Conclusion: Statistical analyses of phytoplankton in 12 large rivers revealed an increase in species richness to the north with community structure changing under stimulation of air temperature, ice-free periods, humidity, and trophic variables were stimulants and water transparency and speed flow were considered stress factors.