Anthropogenic alteration of invertebrate assemblages of the Green River downstream of Flaming Gorge Dam

Valance Brenneis

The ecological patterns and processes occurring in many rivers and streams have been drastically altered by human activities. Along with the changing hydrologic regimes and altered geomorphology caused by dam building and water diversions, the introduction of toxins and non-indigenous species can significantly alter patterns of diversity and abundance of macroinvertebrate assemblages. I begin this paper by reviewing general theory on the ecology of rivers. I then address the ways in which alteration of flow and establishment of invasive species can change aquatic invertebrate assemblages in general. I then focus more specifically on the Green River, particularly the effects of rotenone poisoning and the closure of Flaming Gorge Dam on aquatic invertebrate communities in reaches of the Green River downstream of the dam. Finally, I discuss the recent establishment of the invasive New Zealand mud snail immediately downstream of the dam and possible implications for the entire aquatic food web.