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Photosynthesis in a sub‐Antarctic shore‐zone lichen
Author(s) -
Smith V. R.,
Gremmen N. J. M.
Publication year - 2001
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1046/j.1469-8137.2001.00025.x
Subject(s) - photosynthesis , salinity , respiration , respiration rate , botany , chemistry , biology , ecology
• Photosynthetic responses to moisture, light, temperature, salinity and inorganic nitrogen fertilization are reported for a shore‐zone lichen Turgidiusculum complicatulum (formerly Mastodia tesselata ), a possible recent introduction to sub‐Antarctic Marion Island. • Optimum moisture contents for net photosynthesis were 225–346% (ash free, dry mass). Net CO 2 exchange was dominated by a strong temperature dependence of respiration rate. Net photosynthetic rate responded sharply to increasing PPFD and saturated below 300 µmol m −2 s −1 , but electron transport rate (ETR) increased up to approx. 900 µmol m −2 s −1 PPFD suggesting that gross photosynthesis responded to light to this level. Nonphotochemical fluorescence quenching increased rapidly with PPFD up to approx. 400 µmol m −2 s −1 and thereafter more slowly. Even at high PPFD (1050 µmol m −2 s −1 ) most PSII centres were open. • Salinity did not significantly influence CO 2 assimilation rate; however, NH 4 NO 3 significantly depressed net photosynthesis rate at all salinities except 100% seawater. ETR and dark respiration rate were increased by NH 4 NO 3 . • The response of T. complicatulum to light and temperature enables high rates of CO 2 assimilation under the island’s microclimatic regime; if sufficiently hydrated, the lichen would exhibit near maximal photosynthesis rates for approx. 75% of the photoperiod over the year.