Cyanobacteria in High Latitude Lakes, Rivers and Seas

Abstract

Cyanobacteria often account for a large and sometimes dominant fraction of phototrophic biomass and primary production in high latitude lakes, ponds, streams and wetlands. Picocyanobacteria are usually the most abundant photosynthetic cell type in the plankton of Arctic lakes and rivers, and in East Antarctic saline lakes they have been recorded at cell concentrations of up to 1.5 × 107 per mL. In striking contrast to their success in high latitude lakes, picocyanobacteria are generally absent or sparse in polar seas, with the exception of regions that receive advective inputs of picocyanobacteria from more favourable growth environments. Colonial bloom-forming cyanobacteria are conspicuously absent from most polar freshwaters, but future climate change may favour their development in some areas via warmer temperatures for growth, more stable water columns that favour gas-vacuolate species and richer nutrient conditions as a result of more active catchment processes. Mat-forming cyanobacteria are a ubiquitous element of polar aquatic ecosystems including lakes, ponds, streams and seeps. These consortia of diverse microbial taxa often occur as benthic crusts and films, and in some locations form luxuriant communities up to tens of cm in thickness. They have many biological features that make them well suited to life in the extreme polar environment, including tolerance of persistent low temperatures, freeze-thaw-cycles, high and low irradiances, UV-exposure and desiccation.