Highlights
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Elevated UV-B radiation altered the photosynthetic pigment content of microalgae.
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The chloroplast ultrastructure of microalgae was damaged severely.
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The parameters of chlorophyll fluorescence decreased with UV-B enhancement after 48 h.
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UV-B stress stimulated the ribulose-1,5-bisphosphate carboxylase/oxygenase activity.
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Alterations in energy distribution were observed under diverse doses of UVB radiation.