caa a22 4500 445893931 CHVBK 20180317145625.0 cr unu---uuuuu 170323e20110501xx s 000 0 eng 10.1007/s10750-011-0623-6 doi (NATIONALLICENCE)springer-10.1007/s10750-011-0623-6 Disruption of planktonic phosphorus cycling by ultraviolet radiation [Elektronische Daten] [Jeff Sereda, David Vandergucht, Jeff Hudson] Ultraviolet radiation (UVR) may alter phosphorous (P) cycling by plankton through changes in the acquisition and/or regeneration of dissolved P. However, to date an effect of UVR on the uptake of P has not been observed at ambient phosphate (PO4 3−) concentrations. This has lead to the conclusion that the uptake of P by plankton may be insensitive to UVR. Past research has been limited to a few individual systems, prolonged incubations in bags, or lab cultures. We suspect that experimentation with natural plankton assemblages across broader environmental and/or chemical gradients is required to appreciably understand how UVR may alter P kinetics. Therefore, our study aimed to determine the effect of UVR on the turnover time of the dissolved PO4 3− pool, the regeneration of dissolved P, the turnover rate of particulate P, and on PO4 3− concentrations in natural plankton assemblages across broad environmental and chemical gradients. Second we aimed to assess how UVR may alter phosphatase activity and, determine if a change in phosphatase activity under UVR irradiance is correlated with a change in P uptake as proposed in the literature. Studies were conducted on 18 thermally stratified or polymictic lakes located in Ontario and Saskatchewan, Canada. Lake water samples were exposed to one of three experimental treatments: control, photosynthetically active radiation (PAR), or photosynthetically active radiation plus ultraviolet radiation (PAR+UVR). Our study is the first to demonstrate that UVR exposure has the potential to alter P cycling at ambient (picomolar) PO4 3− concentrations. We have demonstrated that the turnover time of the PO4 3− pool increases under UVR irradiance (i.e., P uptake decreases), while the regeneration rate of dissolved P and turnover rate of planktonic P are generally not affected; with the net effect being an increase in steady state PO4 3− concentration (ssPO4 3−). Alkaline phosphatase activity (APA) in the dissolved and particulate fractions was significantly reduced in PAR+UVR treatments, but unrelated to changes in P uptake. In summary, we have demonstrated that the cycling of P may be disrupted by UVR, with a decrease in the uptake of P and the accumulation of PO4 3− in the dissolved pool. This, in turn may exacerbate planktonic P limitation, alter the nutrient stoichiometry of plankton and/or indirectly alter rates of primary production in limnetic systems. Springer Science+Business Media B.V., 2011 Cycling nationallicence Lakes nationallicence Phosphorus nationallicence Plankton nationallicence Ultraviolet radiation nationallicence Sereda Jeff University of Saskatchewan, W.P. Thompson Building 112 Science Pl, S7N 5E2, Saskatoon, SK, Canada aut Vandergucht David University of Saskatchewan, W.P. Thompson Building 112 Science Pl, S7N 5E2, Saskatoon, SK, Canada aut Hudson Jeff University of Saskatchewan, W.P. Thompson Building 112 Science Pl, S7N 5E2, Saskatoon, SK, Canada aut Hydrobiologia Springer Netherlands 665/1(2011-05-01), 205-217 0018-8158 665:1<205 2011 665 10750 https://doi.org/10.1007/s10750-011-0623-6 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10750-011-0623-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Sereda Jeff University of Saskatchewan, W.P. Thompson Building 112 Science Pl, S7N 5E2, Saskatoon, SK, Canada aut NATIONALLICENCE 700 1- Vandergucht David University of Saskatchewan, W.P. Thompson Building 112 Science Pl, S7N 5E2, Saskatoon, SK, Canada aut NATIONALLICENCE 700 1- Hudson Jeff University of Saskatchewan, W.P. Thompson Building 112 Science Pl, S7N 5E2, Saskatoon, SK, Canada aut NATIONALLICENCE 773 0- Hydrobiologia Springer Netherlands 665/1(2011-05-01), 205-217 0018-8158 665:1<205 2011 665 10750 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer