Water velocity modeling can delineate nearshore and main channel plankton environments in a large river

作者：Ball Emily E; Smith Derek E; Anderson Eric J; Skufca Joseph D; Twiss Michael R^*

来源：Hydrobiologia, 2018, 815(1): 125-140.

DOI：10.1007/s10750-018-3556-5

• Horizontal stratification
• Hydrodynamic modeling
• Nutrients
• Phytoplankton
• St. Lawrence River
• Zooplankton

Methods to distinguish nearshore and main channel ecosystems within large rivers are essential for observing physical, chemical, and biological features that influence overall river ecosystem function. Water velocity fields based on hydrodynamic modeling of water flow trajectory were used to evaluate water history (i.e., water moving slowly as in a slack water region, or more rapidly, as characteristic of the main channel) prior to passing a given point in the Upper St. Lawrence River. Using this method to differentiate zones in the river, observations of biotic and abiotic variables in nearshore and main channel zones during late spring and summer (June-August) were compared to assess the difference in these water column river ecosystems. Differences in plankton community composition between nearshore and main channel waters along the Upper St. Lawrence River were investigated to test the hypothesis that nearshore and main channel environments in large river systems have different biotic (e.g., phytoplankton, crustacean zooplankton, and rotifer concentrations) and abiotic [e.g., water temperature, specific conductivity, silicate, colored dissolved organic matter (CDOM), and total phosphorus] characteristics. Nearshore water had significantly higher concentrations of CDOM and chlorophyll-a than main channel waters. With distance downstream, crustacean zooplankton and rotifers decreased in abundance in both nearshore and main channel regions. This study describes an effective method for stratified sampling design that differentiates nearshore and main channel ecosystems in the water column of large rivers.

• 出版日期2018-6