Response of Freshwater Bloom-Forming Planktonic Cyanobacteria to Global Warming and Nutrient Increase

Abstract

Human activities stimulate changes in aquatic environment, promoting temperature rise and eutrophication. Disturbance in aquatic ecosystems lead to alterations in plankton communities and food web structure. Cyanobacteria, which are able to regulate their buoyancy, are adapted to low-light, high temperatures, are capable to store phosphorus and fix nitrogen, produce toxins, which help to acquire competitive traits over other phytoplankton species. So, increasing temperature and loadings of nutrients in lakes stimulate successful proliferation of cyanobacteria and heavy bloom formation. Usually higher temperature (> 20ºC) and lower N:P mass ratio determine the dominance of cyanobacteria species in lakes and this is expected to increase in the future.

Earth observation for monitoring and mapping of cyanobacteria blooms. Case studies on five Italian lakes

“…Global warming may prolong the annual period of water stratification (Markensten et al, 2010), increasing the dominance of cyanobacteria and nitrogen fixation (Elliott, 2012;Hense et al, 2013). Cyanobacteria generally thrive on higher nutrient loads (N, P), while nutrient stoichiometry determines interspecific competition between cyanobacteria and other algae (Savadova, 2014). Changes in physical parameters such as surface water temperature over time can even lead to algal species succeeding one another during the same bloom, as reported by Wu et al (2016;Dianchi Lake, China).…”