Drivers of phytoplankton community structure change with ecosystem ontogeny during the Quaternary

Aleksandra Cvetkoska,Elena Jovanovska,Torsten Hauffe,Timme H Donders,Zlatko Levkov,Dedmer B Van De Waal,Jane M Reed,Alexander Francke,Hendrik Vogel,Thomas Wilke,Bernd Wagner,Friederike Wagner-Cremer

doi:10.1016/j.quascirev.2021.107046

Abstract

Freshwater species are particularly sensitive to climate fluctuations, but little is known of their response to the large-scale environmental change that took place during the Quaternary. This is partly due to the scarcity of continuously preserved freshwater sedimentary records with orbital chronology. We use a 1.363 Ma high-resolution fossil record of planktonic diatoms from ancient Lake Ohrid to evaluate the role of global and regional versus local-scale environmental change in driving temporal community dynamics. By using a Bayesian joint species distribution model, we found that communities were mostly driven by the local-scale environment. Its effects decreased over time, becoming less important than global and regional environment at the onset of the penultimate glacial, 0.183 Ma. Global and regional control over the environment became important with successive deepening of the lake at around 1.0 Ma, and its influence remained persistent until the present. Our high-resolution data demonstrate the critical role of lake depth and its thermal dynamics in determining phytoplankton response to environmental change by influencing lake mixing, nutrient and light availability.With this study we demonstrate the relative impact of various environmental factors and their scale-dependant effect on the phytoplankton communities during the Quaternary, emphasizing the importance of not only considering climate fluctuations in driving their structure and temporal dynamics but also the local environment.

Highlights

Evidence indicates that many species are unable to change their geographical range to more favorable habitats to avoid extinction (Ceballos and Ehrlich, 2018)
The extinction of some Pantocsekiella taxa defined the collapse of Community I at 0.958 million years (Ma) when deeper water conditions had established in the lake (Fig. 2A)
Our high-resolution time-series data of diatoms in Lake Ohrid shows that taxa abundances and community structure between 1.363 and 0.183 Ma were mainly influenced by the local environment

Summary

Introduction

Evidence indicates that many species are unable to change their geographical range to more favorable habitats to avoid extinction (Ceballos and Ehrlich, 2018). It has been shown that climate driven lake-level fluctuations during the Quaternary have affected community assembly in various freshwater taxa, such as the iconic cichlid fishes from the East African Lake Malawi (Ivory et al, 2016) While this indicates that global and regional climate may play a substantial role in influencing community dynamics over extended periods of time, the relative importance of long-term change in global and regional, or in local environment, in leading to the present-day community structure is poorly understood. Assuming that global and regional forcings over environment will play a predominant role in structuring the planktonic diatom communities throughout the entire record, we analyzed time-series data of relative species abundances against long-term global and regional, and local-scale environmental (bio-geochemical) proxy data and quantified their influence on community composition over time. At present Lake Ohrid is a calcium bicarbonate Ca(HCO3) dominated, oligotrophic lake with an average total phosphorus (TP) concentration of 4.5 mg Â mÀ3 (Matzinger et al, 2007)

Methods

Results

Conclusion