Changes in fluorescence intensity and spectral composition at physical (a) and chemical (b) treatment of Synechocystis aquatilis CALU 1336. (a) – three-days ultrasound treatment of cyanobacterial culture. Excitation wavelengths are shown next to the curves. Inset shows the effect at excitation wavelength 488 nm. (b) – fast dynamics of fluorescence changes during 2 mg/l copper sulfate pentahydrate treatment (CuSO4 x 5H2O). Excitation wavelength 488 nm. Spectra were recorded at 1, 15, 30 and 210 min (3.5 hours). Vertical lines indicate wavelengths for fluorescence maximum of phycocyanin (656 nm) and chlorophyll a (682 nm).