Spatial-temporal effects on fish diversity and assemblages in a highly modified environment

The paddy field is a man-made habitat and is subjected to various agronomic practices but only for a temporary period, in line with the stages of paddy planting. We hypothesised that the spatial scale (types of habitats within a paddy field) and temporal scale (the stages of paddy planting) affect fish diversity and assemblages. We sampled the fish from four different habitats within the paddy field from three different stages of paddy planting, for two seasons of paddy cultivation. There were 26 species of freshwater fishes recorded from 16 families. Generally, the diversity values of fishes across the stages and habitats fluctuate for both seasons. Both spatial and temporal scales have a significant effect on fish diversity (p < 0.05). Fish assemblages later were also separated according to the habitats and stages in the paddy field via nMDS analysis. The results suggest that spatial and temporal effects are important drivers for the changes in fish diversity in an urban environment as well as maintaining the ecosystem balance in man-made habitats.