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Reference Module in Earth Systems and Environmental Sciences

A Diversity of Primary Producers in Lakes

Francesco Pomatia, Marta Reyesa, Anita Narwania, Robert Fischerb, Robert Ptacnikb

Eawag, Department of Aquatic Ecology, Zurich, Switzerland.


Aim: We present the current state of knowledge with regards to the biodiversity of phytoplankton in lakes. We introduce the main concepts of biodiversity and review the mechanisms regulating phytoplankton diversity at local and regional scales. We also list the main methods to study phytoplankton diversity and offer a set of case studies for further reading.

Main concepts: What is biodiversity at the local and regional scale (taxonomic, functional, trait diversity, genetic diversity). How we measure biodiversity (richness, evenness, dissimilarity). The mechanisms regulating phytoplankton biodiversity—community assembly and eco-evolutionary dynamics: regional scale processes and local factors such as selection by abiotic and biotic interactions. The potential for rapid, local and ecologically relevant adaptation of phytoplankton. The issue of scale, and the issue of predictability of phytoplankton dynamics. Consequences of phytoplankton biodiversity change for lake ecosystem services, e.g., increase in prevalence of cyanobacterial blooms.

Main methods: Traditional and new/alternative methods for taxonomic, functional and genetic diversity estimation: traditional sampling and taxonomy, pigment-based estimates of phytoplankton diversity, DNA-barcoding and metagenomics, flow-cytometry, and imaging microscopy. Advantages and limitations of classical and novel approaches to phytoplankton diversity measurements.

Conclusions: Phytoplankton biodiversity in all its components remains unexplored, partially due to the lack of approaches to study microbial communities with large population sizes. More data are particularly needed at the genetic and functional level. The relative importance of different mechanisms driving phytoplankton biodiversity is still debated, and new insights are due to emerging approaches to study communities in their natural environment. We identified knowledge gaps: role of local selection versus spatial (dispersal) processes in community assembly, limits in measuring or inferring ecologically relevant traits (e.g., physiological responses), limits in studying local process at the temporal scale that matters to understand eco-evolutionary dynamics, methods to study spatial processes like dispersal, methods to study single cell genomes and phenotypes.

Keywords: DNA-barcoding, Flow-cytometry, Functional diversity, Genetic diversity, Imaging microscopy, Phytoplankton, Taxonomic diversity, Taxonomy, Traditional monitoringTraits.

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