RESPONSE OF LAMINARIA SACCHARINA (PHAEOPHYTA) GROWTH AND PHOTOSYNTHESIS TO SIMULTANEOUS ULTRAVIOLET RADIATION AND NITROGEN LIMITATION¹

Abstract

The brown macroalga Laminaria saccharina (L.) J. V. Lamour. was grown in large outdoor tanks at 50% ambient solar radiation for 3–4 weeks in July and August of 2000, 2001, and 2002, in either ambient or nitrogen (N)–enriched seawater and in either ambient light [PAR + ultraviolet radiation (UVR)] or ambient light minus UVR. Growth, N‐content, photosynthetic pigments, and RUBISCO content increased in N‐enriched seawater, indicating N‐limitation. UVR inhibited growth, but this inhibition was ameliorated by N‐enrichment. The response of growth to UVR could not be explained by changes in respiration and photosynthesis. Gross light‐saturated photosynthesis (Pmax) remained unaffected by UVR but was significantly higher under N‐enrichment, as was dark respiration (Rd). UVR had no effect on pigments or N content. However, RUBISCO contents were low in the presence of UVR, reflecting the overall change in soluble cellular protein. Overall, our data indicate that the response to UVR in L. saccharina depends on other environmental factors, such as N, and these effects need to be considered when evaluating the response of macroalgae to increased UVR.

Nitrate Assimilation: The Role of In Vitro Nitrate Reductase Assay as Nutritional Predictor

“…Nitrogen depletion has been shown to increase photoinhibitory responses in the photosynthesis of marine organisms, including macroalgae (Korbee-Peinado et al, 2004;Huovinen et al, 2006). On the other hand, photosynthetic pigments, through generally being positively correlated with nitrogen availability, rapidly respond to varying nitrogen levels (Davison et al, 2007). For example, phycobiliproteins, reported as nitrogen-storage compounds in N-rich conditions, act as nitrogen sources under N-limiting conditions (Lobban et al, 1985).…”

A comprehensive cDNA library of light- and temperature-stressedSaccharina latissima(Phaeophyceae)

“…Many studies have been conducted on the growth and photosynthetic performance of S. latissima sporophytes under various abiotic conditions (Davison, 1987;Davison & Davison, 1987;Davison et al, 1991;Bruhn & Gerard, 1996;Machalek et al, 1996;Spurkland & Iken, 2011); other studies have focused on their reproduction (Lu¨ning & Dring, 1972, 1975Lu¨ning, 1980Lu¨ning, , 1981aLu¨ning, , 1981b. Recent research has been dominated by studies of the impact of increased UV radiation on photosynthesis and growth on different life stages of S. latissima (Apprill & Lesser, 2003;Wiencke et al, 2004;Roleda et al, 2006aRoleda et al, , 2006bRoleda et al, , 2007Davison et al, 2007).…”

Efeitos da radiação UV-B em variantes cromáticas de Gracilaria birdiae (Gracilariales, Rhodophyta): crescimento, conteúdo pigmentar, fotossíntese e ultra-estrutura

“…Apesar das macroalgas apresentarem uma grande diversidade de respostas a altas irradiâncias, uma taxa relativamente elevada de fotoinibição em algas entremarés ocorre quando a maré baixa coincide com a radiação solar do meio dia (Roleda et al, 2004b). Nas macroalgas, o rendimento quântico efetivo (∆F/F m' ), calculado a partir da fluorescência in vivo da clorofila, é freqüentemente utilizado para determinar o efeito à curto prazo da radiação UV-B na fotossíntese (Davison et al, 2007). A inibição de ∆F/F m' em decorrência da exposição à UV-B foi observada para as algas pardas Fucus distichus (Halnet et al, 1997), Laminaria saccharina (Halnet et al, 1997;Davison et al, 2007), L. digitata, Alaria esculenta (Halnet et al, 1997) e Macrocystis pyrifera (Aguirre-von-Wobeser et al, 2000).…”

“…Nas macroalgas, o rendimento quântico efetivo (∆F/F m' ), calculado a partir da fluorescência in vivo da clorofila, é freqüentemente utilizado para determinar o efeito à curto prazo da radiação UV-B na fotossíntese (Davison et al, 2007). A inibição de ∆F/F m' em decorrência da exposição à UV-B foi observada para as algas pardas Fucus distichus (Halnet et al, 1997), Laminaria saccharina (Halnet et al, 1997;Davison et al, 2007), L. digitata, Alaria esculenta (Halnet et al, 1997) e Macrocystis pyrifera (Aguirre-von-Wobeser et al, 2000). Entre as algas vermelhas, Palmaria palmata apresentou resultados semelhantes (Halnet et al, 1997;Poppe et al, 2002;.…”

“…A inibição do crescimento foi verificada para algas pardas como, Laminaria saccharina (Davison et al, 2007), L. ochroleuca (Roleda et al, 2004a) e Fucus gardneri (Brianne et al, 2004), após serem expostas a UV-B por um período de três a quatro semanas. Entre as Rhodophyta, um estudo realizado em Gracilaria lameneformis, registrou uma queda nas taxas de crescimento após três semanas de exposição à radiação UV (Xu & Gao, 2007).…”