Spatiotemporal metacommunity dynamics in a desert river system

Background/Question/Methods

Desert river systems are characterized by highly fluctuating environmental conditions such as periodic droughts and intense desert rains. These changing environmental conditions in desert river systems can cause difficulties in determining the effects of local and regional factors on aquatic communities. In this study, we hypothesized that fish assemblages in the mainstems of desert river networks are largely affected by fish dispersal, whereas, fish assemblages in tributaries of desert river networks are determined more by local environmental processes. We also hypothesized that the relative effect of local and regional processes on fish assemblages would vary temporally. To test these hypotheses, we examined the relationships among seasonal fish assemblages, spatial position and local environmental factors in the Rio Grande and its tributaries in the Trans-Pecos region of Texas.

Results/Conclusions

Fish assemblages in the tributaries significantly differed across the study sites and were strongly related to both spatial position and local environmental factors throughout the year. In contrast, fish assemblages in the Rio Grande had lower beta diversity than those in the tributaries and were significantly related to spatial position only in certain seasons (November to March). Our results suggest that the relative effects of local and regional environmental factors on fish assemblages vary spatially and temporally in the Rio Grande system.