The response of the early developmental stages of Laminaria japonica to enhanced ultraviolet-B radiation

The responses of the early development of Laminaria japonica collected from Kiaochow Bay in China to enhanced ultraviolet-B radiation (UV-B, 280–320 nm) were studied in the laboratory. The low UV-B radiations (11.7–23.4 J·m−2·d−1) had no significant effects on zoospores attachment, but when the UV-B dose > 35.1 J·m−2·d−1 the attachment decreased significantly compared with the control. Germination of embryospores was >93% under the low (11.7–35.1 J·m−2·d−1) doses, and in the range of 78.5%–88.5% under the high (46.8–70.2 J·m−2·d−1) UV-B doses, indicating a significant radiation effect. Under the higher UV-B exposure (35.1–70.2 J·m−2·d−1), all of the few gametophytes formed from embryospores died 120 h post-release. After exposure to the low UV-B radiation (11.7–23.4 J·m−2·d−1), the formation of sporophytes decreased and the female gametophyte clones increased compared with the control. However, the sex ratio and the relative growth of female gametophytes/sporophytes had not significantly changed. According to the results, enhanced UV-B radiation has a significant effect on the early development of L. japonica under laboratory conditions, suggesting that the UV-B radiation could not be overlooked as one of the important environmental factors influencing the ontogeny of macroalgae living in marine ecosystems.