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Contrasting cyanobacterial communities and microcystin concentrations in summers with extreme weather events: insights into potential effects of climate change
Ist Teil von
Hydrobiologia, 2017, Vol.785 (1), p.71-89
Ort / Verlag
Cham: Springer International Publishing
Erscheinungsjahr
2017
Quelle
2022 ECC(Springer)
Beschreibungen/Notizen
Current climate change scenarios predict that aquatic systems will experience increases in temperature, thermal stratification, water column stability and in some regions, greater precipitation. These factors have been associated with promoting cyanobacterial blooms. However, limited data exist on how cyanobacterial composition and toxin production will be affected. Using a shallow eutrophic lake, we investigated how precipitation intensity and extended droughts influenced: (i) physical and chemical conditions, (ii) cyanobacterial community succession, and (iii) toxin production by
Microcystis
. Moderate levels of nitrate related to intermittent high rainfall during the summer of 2013–2014, lead to the dominance of
Aphanizomenon gracile
and
Dolichospermum
crassum
(without heterocytes).
Microcystis aeruginosa
blooms occurred when ammonium concentrations and water temperature increased, and total nitrogen:total phosphorus ratios were low. In contrast, an extended drought (2014–2015 summer) resulted in prolonged stratification, increased dissolved reactive phosphorus, and low dissolved inorganic nitrogen concentrations. All
A. gracile
and
D. crassum
filaments contained heterocytes,
M. aeruginosa
density remained low, and the picocyanobacteria
Aphanocapsa
was abundant. A positive relationship (
P
< 0.001) was identified between microcystin quotas and surface water temperature. These results highlight the complex successional interplay of cyanobacteria species and demonstrated the importance of climate through its effect on nutrient concentrations, water temperature, and stratification.