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Table 1

Mean and standard deviations of environmental parameters of the Foum-Gleita reservoir (Mauritania) during one-year study period (from September 2017 to August 2018). T: surface water temperature; pH: water hydrogen potential; Secchi: secchi disk depth; DO: dissolved oxygen; N-NO3 : nitrate; N-NO2 : nitrite; N-NH4 +: ammonium; DIN: dissolved inorganic nitrogen; P-PO4 −3: dissolved phosphorus (DIP); TP: total phosphorus; DIN/TP: DIN:TP mass ratio; Fe: iron; Chl-a: chlorophyll a. The significance of the regression coefficients (Pearson?s r) is indicated by *0.01 < p < 0.05, **0.001 < p < 0.01, and ***p < 0.001.Values followed by the different letters are significantly different (p < 0.05). N: number of samples; SD: standard deviation; *: p < 0.05.

Parameters S1 (N = 12)   S2 (N = 12) S3 (N = 12) Difference between sites
(one- way ANOVA)




Mean ± SD Range   Mean ± SD Range Mean ± SD Range F p-values
T (°C) 27.8 ± 3.6 20.2–30.3   27.8 ± 3.6 20.3–30.4 27.36 ± 3.4 21.1–30.2 F2, 33 = 0.040 0.996
DO (mg L−1) 10.06 ± 2.55 6.20–15.4   9.55 ± 2.94 6.60–17.8 7.83 ± 2.90 5.00–14.7 F2, 33 = 2.022 0.148
pH 7.6 ± 0.2 7.1–7.9   7.5 ± 0.2 7.1–7.96 7.6 ± 0.27 7.1–8.06 F2, 33 = 0.604 0.553
Salinity (psu) 0.27 ± 0.08 0.19–0.51   0.26 ± 0.07 0.20–0.49 0.27 ± 0.07 0.22–0.47 F2, 33 = 0.058 0.943
Secchi (m) 0.32 ± 0.09 0.19–0.45   0.31 ± 0.10 0.16–0.45 0.33 ± 0.10 0.19–0.48 F2, 33 = 0.132 0.877
N-NO3 (mg L−1) 3.03 ± 1.45 1.22–5.13   3.53 ± 1.22 1.72–5.06 4.19 ± 1.37 1.89–6.17 F2, 33 = 2.221 0.124
N-NO2 (mg L−1) 0.03 ± 0.01a 0.01–0.06   0.03 ± 0.01a 0.02–0.06 0.06 ± 0.02b 0.03–0.13 F2, 33 = 6.434 0.004*
N-NH4 + (mg L−1) 0.19 ± 0.05a 0.12–0.28   0.14 ± 0.03b 0.11–0.21 0.20 ± 0.05ac 0.13–0.27 F2, 33 = 5.503 0.009*
DIN (mg L−1) 3.27 ± 1.44 1.39–5.32   3.71 ± 1.22 1.87–5.23 4.46 ± 1.36 2.16–6.53 F2, 33 = 2.386 0.108
P-PO4 −3 (mg L−1) 0.28 ± 0.10 0.15–0.42   0.24 ± 0.05 0.16–0.32 0.30 ± 0.13 0.15–0.50 F2, 33 = 1.228 0.306
TP (mg L−1) 0.32 ± 0.09 0.22–0.44   0.27 ± 0.05 0.21–0.36 0.36 ± 0.14 0.23–0.56 F2, 33 = 2.312 0.115
DIN/TP 11.99 ± 7.41 3.39–21.28   14.51 ± 6.74 5.19–22.74 1 3.49 ± 7.77 4.70–23.00 F2, 33 = 0.505 0.608
Fe (mg L−1) 0.12 ± 0.05 0.08–0.24   0.15 ± 0.04 0.10–0.25 0.15 ± 0.06 0.06–0.26 F2, 33 = 0.905 0.414
Chl-a (μg L−1) 6.62 ± 2.03a 4.15–10.65   7.17 ± 2.27ab 4.23–11.13 10.16 ± 4.91b 4.16–18.11 F2, 33 = 3.899 0.030*

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