caa a22 4500 445890061 CHVBK 20180317145613.0 cr unu---uuuuu 170323e20110501xx s 000 0 eng 10.1007/s11120-011-9655-z doi (NATIONALLICENCE)springer-10.1007/s11120-011-9655-z The effects of copper on the photosynthetic response of Phaeocystis cordata [Elektronische Daten] [Ana Lombardi, Maria Maldonado] We investigated the effects of limiting (1.96×10−9moll−1 total Cu, corresponding to pCu 14.8; where pCu=−log [Cu2+]) and toxic Cu concentrations up to 8.0×10−5moll−1 total Cu (equivalent to pCu 9.5) on growth rates and photosynthetic activity of exponentially grown Phaeocystis cordata, using batch and semi-continuous cultures. With pulse amplitude modulated (PAM) fluorometry, we determined the photochemical response of P. cordata to the various Cu levels, and showed contrasting results for the batch and semi-continuous cultures. Although maximum photosystem II (PSII) quantum yield (ΦM) was optimal and constant in the semi-continuous P. cordata, the batch cultures showed a significant decrease in ΦM with culture age (0-72h). The EC50 for the batch cultures was higher (2.0×10−10moll−1, pCu9.7), than that for the semi-continuous cultures (6.3×10−11moll−1, pCu10.2). The semi-continuous cultures exhibited a systematic and linear decrease in ΦM as Cu levels increased (for [Cu2+]<1.0×10−12moll−1, pCu12.0), however, no effect of high Cu was observed on their operational PSII quantum yield (Φ′M). Similarly, semi-continuous cultures exhibited a significant decrease in ΦM, but not in Φ′M, because of low-Cu levels. Thus, Cu toxicity and Cu limitation damage the PSII reaction centers, but not the processes downstream of PSII. Quenching mechanisms (NPQ and Q n) were lower under high Cu relative to the controls, suggesting that toxic Cu impairs photo-protective mechanisms. PAM fluorometry is a sensitive tool for detecting minor physiological variations. However, culturing techniques (batch vs. semi-continuous) and sampling time might account for literature discrepancies on the effects of Cu on PSII. Semi-continuous culturing might be the most adequate technique to investigate Cu effects on PSII photochemistry. Springer Science+Business Media B.V., 2011 Phaeocystis cordata nationallicence Photosynthesis nationallicence Copper nationallicence Chlorophyll fluorescence nationallicence Phytoplankton nationallicence Lombardi Ana Department of Earth and Ocean Sciences, University of British Columbia, V6T 1Z4, Vancouver, BC, Canada aut Maldonado Maria Department of Earth and Ocean Sciences, University of British Columbia, V6T 1Z4, Vancouver, BC, Canada aut Photosynthesis Research Springer Netherlands 108/1(2011-05-01), 77-87 0166-8595 108:1<77 2011 108 11120 https://doi.org/10.1007/s11120-011-9655-z text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11120-011-9655-z text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Lombardi Ana Department of Earth and Ocean Sciences, University of British Columbia, V6T 1Z4, Vancouver, BC, Canada aut NATIONALLICENCE 700 1- Maldonado Maria Department of Earth and Ocean Sciences, University of British Columbia, V6T 1Z4, Vancouver, BC, Canada aut NATIONALLICENCE 773 0- Photosynthesis Research Springer Netherlands 108/1(2011-05-01), 77-87 0166-8595 108:1<77 2011 108 11120 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer