Most abundant diatom species in the dry and wet seasons. Log-transformed abundance (a) of dominant diatom species and their contributions (%) to the seasonal difference in the epilithic algal compositions on the insect-excluded bricks (b). The average dissimilarity between the dry and wet seasons was 57.4%. Diatom species in the x-axis were ranked in order of descending contributions (%) to the difference between the dry and wet seasons on the insect-excluded bricks. COCPL, Cocconeis placentula var. euglypta; ACHPY, Achnanthidium pyrenaicum; GOMSP, Gomphonema spp.; ACHSP, Achnanthes spp.; ACHMI, Achnanthidium minutissimum; PLALA, Planothidium lanceolatum.