Effects of UV-B radiation on Gelidium floridanum (Rhodophyta, Gelidiales): germination of tetraspores and early sporeling development
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- Scariot, L.Â., Rover, T., Zitta, C.S. et al. J Appl Phycol (2013) 25: 537. doi:10.1007/s10811-012-9888-z
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The increased incidence of UV-B radiation, particularly in southern South America, has sparked more interest in its effects on marine organisms. Here we describe the effects of UV-B on the early life stages of Gelidium floridanum, an agar-producing species abundant on rocky coasts in southern Brazil. Treated samples were submitted to 0.12 W m−2 of artificial UV-B radiation for 2 h per day over a 15-day period. UV-B exposure induced impairment of tetraspore germination and germling development. We observed a delay in germination, a reduced growth rate of tetrasporelings, and morphological changes, such as a different length-to-width ratio, twisted thallus, loss of pigmentation, and differentiation of more than one apical cell, all leading to a different growth pattern in sporelings that survived treatment. Results indicated a great susceptibility of early-developing Gelidium to UV-B, even at low irradiance and short exposure time.