## 3 Results  
### Physical, Chemical, and Phytoplankton Properties (In Situ)  
The surface water temperature ranged from 3.41 to 27.60 \({}^{\circ}\)C during the water sampling, and spatial variations were relatively low (<1.61 \({}^{\circ}\)C) compared with other properties (Table 1). Turbidity in the water column ranged from 4.70 to 114.90 NTU with values in the upper region higher than in the lower region, except for samples taken in November 2009. PAR at 1.1 m water depth ranged from 1.07 to 363.40 (\(\mu\)mol m\({}^{-2}\) s\({}^{-1}\)), and increased as turbidity decreased. DIN and DIP concentrations ranged from 119.47 to 297.66 \(\mu\)M and from 0.19 to 6.13 \(\mu\)M, respectively, decreasing downstream except for DIP in May 2009. The DSi concentrations ranged from 15.93 to 168.96 \(\mu\)M with no clear spatial variability. DIN/DIP ratios ranged from 41.63 to 1050.75 higher than the Redfield ratio (16:1), and DIN/DSi ratios ranged from 0.89 to 12.78. DIP and DSi concentrations were low in May 2009 compared to other seasons, which contributed to the high DIN/DIP and DIN/DSi ratios. Total chl \(a\) concentration ranged from 3.26 to 109.04 \(\mu\)g L\({}^{-1}\) decreasing downstream (Table 2). The net-sized chl \(a\) concentration ranged from 0.10 to 9.44 \(\mu\)g L\({}^{-1}\). Nanosized chl \(a\) concentration ranged from 1.38 to 99.60 \(\mu\)g L\({}^{-1}\) decreasing downstream, similar to total chl \(a\), and the nanosized class dominated (65-99%) the size structure except at St. C in May 2009 (34%). Diatoms are the most ubiquitous taxonomic group in the freshwater zone. They displayed relatively high cell abundance and contribution percentages (>67%) during the dry and cold seasons (January-March), except at St. C in March 2010 (37%). The most dominant species was _Stephanodiscus_ sp. (Bacillustiophyta) during this period, especially in January 2010 at St. A (84%). Cell abundances of chlorophytes and cyanobacteria were high during the warm seasons, especially in May 2009. Cryptophytes abundance was consistently high during the sampling periods, except in August 2009, with the most dominant species being _Teleaulax acuta (formerly Cryptomonas acuta)_, especially in November 2009. A list of genera/species that appeared at the stations during the sampling period is presented in Table S1. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline
**Sampling Date** & **Station** & **Temp (\({}^{\circ}\)C)** & **Turb (NTU)** & **PAR (\({}_{\text{t}\text{a}\text{m}}\)m \({}^{-2}\) s\({}^{-1}\))** & **(\({}_{\text{t}\text{M}}\))** & **(\({}_{\text{t}\text{M}}\))** & **(\({}_{\text{t}\text{M}}\))** & **(\({}_{\text{t}\text{M}}\))** & **DIN/DSi** \\ \hline \multirow{4}{*}{May 2009} & A & 19.76 & 12.30 & 38.01 & 272.63 & 0.31 & 23.23 & 888.76 & 11.74 \\  & B & 19.64 & 8.90 & 219.80 & 214.45 & 0.40 & 20.47 & 531.33 & 10.48 \\  & C & 19.08 & 6.50 & 224.40 & 203.57 & 0.19 & 15.93 & 1050.75 & 12.78 \\ \cline{2-10}  & A & 26.68 & 36.20 & 1.07 & 205.48 & 4.20 & 124.17 & 48.95 & 1.65 \\  & B & 27.60 & 23.10 & 52.38 & 150.05 & 3.33 & 168.96 & 45.12 & 0.89 \\  & C & 27.07 & 15.30 & 146.53 & 137.92 & 3.07 & 148.02 & 44.96 & 0.93 \\ \cline{2-10}  & A & 9.45 & 14.70 & 20.41 & 255.43 & 6.13 & 116.06 & 41.63 & 2.20 \\  & B & 10.22 & 114.90 & 78.33 & 155.88 & 1.74 & 131.72 & 89.40 & 1.18 \\  & C & 11.06 & 12.50 & 272.70 & 119.47 & 1.16 & 127.95 & 102.77 & 0.93 \\ \cline{2-10}  & A & 3.69 & 11.40 & 6.36 & 297.66 & 4.52 & 80.42 & 65.85 & 3.70 \\  & B & 3.62 & 9.20 & 25.22 & 251.74 & 1.78 & 38.59 & 141.75 & 6.52 \\  & C & 3.41 & 4.70 & 363.40 & 157.82 & 0.90 & 84.69 & 174.56 & 1.86 \\ \cline{2-10}  & A & 9.64 & 11.80 & 23.04 & 219.04 & 3.00 & 120.72 & 72.94 & 1.81 \\  & C & 8.94 & 8.70 & 98.78 & 216.09 & 2.52 & 131.47 & 85.80 & 1.64 \\ \cline{2-10}  & A & 3.56 & 9.80 & 7.25 & 329.41 & 2.26 & 231.22 & 145.74 & 1.42 \\ \hline \end{tabular}
\end{table}