Browsing by Subject "Macrophytes"

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    High Frequency Oxygen Data from Eight Shallow Prairie Pothole Lakes, 2009-2013
    (2020-10-15) Rabaey, Joseph S; Cotner, James B; Zimmer, Kyle D; Domine, Leah M; Rabae005@umn.edu; Rabaey, Joseph S; University of Minnesota Cotner Lab
    Dissolved oxygen controls important processes in lakes, from chemical reactions to organism community structure and metabolism. In shallow lakes, small volumes allow for large fluctuations in dissolved oxygen concentrations, and the oxygen regime can greatly affect ecosystem-scale processes. This data includes high frequency dissolved oxygen measurements that we used to examine differences in oxygen regimes between two alternative stable states that occur in shallow lakes. We compared annual oxygen regimes in four macrophyte-dominated, clear state lakes to four phytoplankton-dominated, turbid state lakes by quantifying oxygen concentrations, anoxia frequency, and measures of whole-lake metabolism. Oxygen regimes were not significantly different between lake states throughout the year except for during the winter under-ice period. During winter, clear lakes had less oxygen, higher frequency of anoxic periods, and higher oxygen depletion rates. Oxygen depletion rates correlated positively with peak summer macrophyte biomass. Due to lower levels of oxygen, clear shallow lakes may experience anoxia more often and for longer duration during the winter, increasing the likelihood of experiencing fish winterkill. These observations have important implications for shallow lake management, which typically focuses efforts on maintaining the clearwater state.
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    Phenology data for watermilfoil taxa Myriophyllum spicatum, M. sibiricum, and M. spicatum x M. sibiricum in Minnesota, USA, 2017 - 2018
    (2021-11-15) Glisson, Wesley J; Larkin, Daniel J; wjglisson@gmail.com; Glisson, Wesley; Minnesota Aquatic Invasive Species Research Center
    In North America, the hybrid aquatic plant Myriophyllum spicatum × Myriophyllum sibiricum (hybrid watermilfoil, HWM) is a cross between non-native invasive Eurasian watermilfoil (M. spicatum, EWM) and native northern watermilfoil (M. sibiricum, NWM). We compared HWM to its parental taxa, EWM and NWM, by examining the amount and timing of: 1) flowering, 2) surface cover, and 3) biomass (using stem counts as a proxy). We conducted repeat surveys of Myriophyllum beds at eight lakes (2–3 lakes/taxon) in the Minneapolis-St. Paul Metropolitan area (Minnesota, USA) between June 2017 and November 2018. To sample biomass without destroying plants, we developed a novel sampling device that uses underwater video to measure Myriophyllum stems; we validated the utility of this device by comparing Myriophyllum stem counts and biomass collected from the same locations. The data from these studies are provided and documented here.