Warmer climates boost cyanobacterial dominance in shallow lakes
Global Change Biology, Vol. 18, p.118-126. ISSN 1354-1013.
Kosten, S.; Huszar, V.L.M; Bécares, E.; Costa, L.S.; Van Donk, E.; Hansson, L-A.; Jeppesen, E.; Kruk, C.; Lacerot, G.; Mazzeo, N.; De Meester, L.; Moss, B.; Lürling, M.; Nõges, T.; Romo, S.; Scheffer, M.
Dominance by cyanobacteria hampers human use of lakes and reservoirs worldwide. Previous studies indicate that
excessive nutrient loading and warmer conditions promote dominance by cyanobacteria, but evidence from global
scale field data has so far been scarce. Our analysis, based on a study of 143 lakes along a latitudinal transect ranging
from subarctic Europe to southern South America, shows that although warmer climates do not result in higher overall
phytoplankton biomass, the percentage of the total phytoplankton biovolume attributable to cyanobacteria
increases steeply with temperature. Our results also reveal that the percent cyanobacteria is greater in lakes with high
rates of light absorption. This points to a positive feedback because restriction of light availability is often a consequence
of high phytoplankton biovolume, which in turn may be driven by nutrient loading. Our results indicate a
synergistic effect of nutrients and climate. The implications are that in a future warmer climate, nutrient concentrations
may have to be reduced substantially from present values in many lakes if cyanobacterial dominance is to be