Taxonomic and Functional Diversity of Fish Communities Between Urbanised and Protected Subtropical Streams

Urbanisation can have significant effects on stream ecosystems through increasing levels of nutrients and contaminants and via altering channel stability. In the present study, we assessed the influence of urban pollution on fish taxonomic and functional diversity. Physico‐chemical variables as well as fish taxonomic and functional diversity metrics were assessed and compared between protected and urban streams. The results indicated that urban and protected streams varied in terms of both physico‐chemical variables and species composition. In addition, urban streams displayed signs of urban stream syndrome, characterised by higher total dissolved solids (TDS), low water resistivity and were at lower elevations. Overall, no significant differences were observed in terms of both taxonomic and functional diversity metrics between the urban and protected streams, which could be indicative of resilience to current environmental conditions in urban streams. Thus, environmental filtering was not enough to induce detectable taxonomic and functional diversity responses. Similarly, functional redundancy could have enhanced community resilience against the effects of disturbances. The congruence in results of taxonomic and functional diversity metrics suggests that the two approaches can be used in concert to assess the influence of urban pollution on fish communities.