caa a22 4500 445893516 CHVBK 20180317145624.0 cr unu---uuuuu 170323e20110201xx s 000 0 eng 10.1007/s10750-010-0545-8 doi (NATIONALLICENCE)springer-10.1007/s10750-010-0545-8 Effects of freshwater input on nutrient loading, phytoplankton biomass, and cyanotoxin production in an oligohaline estuarine lake [Elektronische Daten] [Sibel Bargu, John White, Chunyan Li, Jessica Czubakowski, Robinson Fulweiler] Pulsed river water events can increase nutrient levels potentially translating into enhanced primary production, phytoplankton community shifts, and bloom formation. The Bonnet Carré Spillway is a managed river diversion which can be used to redirect a significant amount of Mississippi River water into Lake Pontchartrain, reducing the risks of flood in the downstream communities during runoff seasons. We investigated nutrient enrichment and consequent changes in phytoplankton biomass, including toxic species in Lake Pontchartrain during and after a 1-month Bonne Carré Spillway opening in 2008. Water samples were collected along a 30km transect. A freshwater plume was found to have formed by the strong river input that had limited mixing with the lake during the opening. The plume and lake water gradually mixed together after the Spillway was closed, indicated by the reduction of the horizontal salinity gradient. The river pulse increased the lake nitrate and dissolved reactive phosphorus concentrations to more than five times the lake background in the plume stations. Nutrient concentrations decreased rapidly after the Spillway closure as the plume dissipated. Diatoms and chlorophytes dominated the system during the opening. After the Spillway closure, there was a shift over time from diatom dominance to toxic cyanobacteria dominance that corresponded to more stable, warmer, and nutrient-limited water conditions. Associated toxins were present and varied over time and space. Further research on the phytoplankton assemblages on the lake is needed in subsequent, non-Spillway opening years to evaluate the impact of river water pulses on the development of these toxic cyanobacterial blooms. Springer Science+Business Media B.V., 2010 River diversions nationallicence Lake Pontchartrain nationallicence Mississippi River nationallicence Nutrient enrichment nationallicence Cyanobacterial blooms nationallicence Microcystin nationallicence Bargu Sibel Department of Oceanography and Coastal Sciences, School of the Coast and Environment, Louisiana State University, 70803, Baton Rouge, LA, USA aut White John Department of Oceanography and Coastal Sciences, School of the Coast and Environment, Louisiana State University, 70803, Baton Rouge, LA, USA aut Li Chunyan Department of Oceanography and Coastal Sciences, School of the Coast and Environment, Louisiana State University, 70803, Baton Rouge, LA, USA aut Czubakowski Jessica Department of Oceanography and Coastal Sciences, School of the Coast and Environment, Louisiana State University, 70803, Baton Rouge, LA, USA aut Fulweiler Robinson Department of Earth Sciences, Boston University, 02215, Boston, MA, USA aut Hydrobiologia Springer Netherlands 661/1(2011-02-01), 377-389 0018-8158 661:1<377 2011 661 10750 https://doi.org/10.1007/s10750-010-0545-8 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10750-010-0545-8 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Bargu Sibel Department of Oceanography and Coastal Sciences, School of the Coast and Environment, Louisiana State University, 70803, Baton Rouge, LA, USA aut NATIONALLICENCE 700 1- White John Department of Oceanography and Coastal Sciences, School of the Coast and Environment, Louisiana State University, 70803, Baton Rouge, LA, USA aut NATIONALLICENCE 700 1- Li Chunyan Department of Oceanography and Coastal Sciences, School of the Coast and Environment, Louisiana State University, 70803, Baton Rouge, LA, USA aut NATIONALLICENCE 700 1- Czubakowski Jessica Department of Oceanography and Coastal Sciences, School of the Coast and Environment, Louisiana State University, 70803, Baton Rouge, LA, USA aut NATIONALLICENCE 700 1- Fulweiler Robinson Department of Earth Sciences, Boston University, 02215, Boston, MA, USA aut NATIONALLICENCE 773 0- Hydrobiologia Springer Netherlands 661/1(2011-02-01), 377-389 0018-8158 661:1<377 2011 661 10750 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer