Table 4 Marginal effects of each of the measured environmental variables on total fish and species abundances. RDA analyses were performed on average numerical data of three seasons (August, December, and March) in the year 2013/2014. All variables except pH were log-transformed before analysis. *significant at P < 0.05, **significant at P < 0.01

Pool (habitat)

0.159

6.435

0.003^**

Depth

0.126

4.906

0.004^**

Gereb Tsedo (GTS) stream

0.126

4.915

0.006^**

Elala (ELA) stream

0.126

4.915

0.003^**

Corixidae

0.125

4.865

0.012^*

Tabanidae

0.120

4.631

0.016^*

Riffle (habitat)

0.118

4.557

0.012^*

Lymnaeidae

0.079

2.917

0.051

Damselfly larvae

0.074

2.705

0.049^*

Dissolved oxygen

0.070

2.551

0.050

Velocity

0.040

1.427

0.058

Transparency (Snell)

0.037

1.304

0.051

Naucoridae

0.065

2.347

0.107

Planorbidae

0.052

1.869

0.133

Turbidity

0.051

1.819

0.136

Chl a

0.049

1.733

0.162

Psychodidae

0.033

1.172

0.284

Dragonfly larvae

0.032

1.127

0.312

Riparian cover

0.029

1.031

0.053

Gerridae

0.028

0.987

0.318

Herudinia

0.023

0.807

0.400

Temperature

0.022

0.780

0.402

Chironomid

0.018

0.611

0.545

Ephydridae

0.017

0.599

0.534

Mayfly larvae

0.016

0.543

0.567

Run (habitat)

0.015

0.512

0.653

Cuilcidae

0.015

0.501

0.629

Macrophytes

0.013

0.462

0.650

pH

0.013

0.453

0.602

Syrphidae

0.012

0.403

0.696

Nepidae

0.011

0.373

0.705

Altitude

0.070

0.242

0.807

Dystiscidae

0.070

0.238

0.820