Human modifications to estuaries correlate with the morphology and functional roles of coastal fish.

Abstract Animals can respond to human impacts by favouring different morphological traits or by exploiting different food resources. We quantified the morphology and diet of four functionally different fish species (n = 543 fish) from 13 estuaries with varying degrees of human modification in Queensland, Australia. We found differences in the responses of trophic groups to the environmental conditions of estuaries; principally the extent of seagrass in the estuary, and the amount of shoreline and catchment urbanisation. Here, seagrass and urbanisation extent correlated with the diet and morphology of zooplanktivores and detritivores; thereby indicating that human modifications may modify these species functional roles. Conversely, environmental variables did not correlate with the diet or morphology of zoobenthivores or piscivores thereby indicating that human modifications may have less an effect on these species functional roles. Our findings demonstrate that anthropogenic impacts to coastal ecosystems might extend from the traditionally measured metrics of abundance and diversity.