The mean values of environmental variables are shown in Table I. The conductivity varied from
22 µS·cm−1 (S1) to 61.5 µS·cm−1 (S4). The water of Banco River was acid with low variation in
pH (4.5 (S1)–6.1 (S3)) between sampling sites. It was the same for water temperature, which
ranged between 25.87 ◦C and 26.43 ◦C. The lowest dissolved oxygen values were recorded
in permanent pools (≤ 2.64 mg·L−1) and the highest values were observed in river channel
stations (≥ 4.12 mg·L−1). Generally, low turbidity (≤ 13.15 NTU) was observed in upstream
areas, while high values (≥ 30 NTU) were recorded in the other sites. The upstream stations
(S1 and S2) presented low values of velocity (≤ 0.25 m·S−1), while high values (≥ 0.33 m·S−1)
were recorded in the middle and downstream stations (S3 and S5). In the permanent pools,
width was almost constant, while it increased from upstream to downstream (2.77 to 4.61 m)
in the river channel. The depth in the study areas varied from 0.14 m (S1) to 0.48 m (S5).