02442nas a2200193   4500008004100000245008700041210006900128300001600197490000800213520183500221100002402056700001702080700002302097700002102120700002002141700002202161700002002183856004502203       2017                        eng d00aGroundwater declines are linked to changes in Great Plains stream fish assemblages0 aGroundwater declines are linked to changes in Great Plains strea  a7373 - 73780 v1143 a<p>Groundwater pumping for agriculture is a major driver causing declines of global freshwater ecosystems, yet the ecological consequences for stream fish assemblages are rarely quantified. We combined retrospective (1950&ndash;2010) and prospective (2011&ndash;2060) modeling approaches within a multiscale framework to predict change in Great Plains stream fish assemblages associated with groundwater pumping from the United States High Plains Aquifer. We modeled the relationship between the length of stream receiving water from the High Plains Aquifer and the occurrence of fishes characteristic of small and large streams in the western Great Plains at a regional scale and for six subwatersheds nested within the region. Water development at the regional scale was associated with construction of 154 barriers that fragment stream habitats, increased depth to groundwater and loss of 558 km of stream, and transformation of fish assemblage structure from dominance by large-stream to small-stream fishes. Scaling down to subwatersheds revealed consistent transformations in fish assemblage structure among western subwatersheds with increasing depths to groundwater. Although transformations occurred in the absence of barriers, barriers along mainstem rivers isolate depauperate western fish assemblages from relatively intact eastern fish assemblages. Projections to 2060 indicate loss of an additional 286 km of stream across the region, as well as continued replacement of large-stream fishes by small-stream fishes where groundwater pumping has increased depth to groundwater. Our work illustrates the shrinking of streams and homogenization of Great Plains stream fish assemblages related to groundwater pumping, and we predict similar transformations worldwide where local and regional aquifer depletions occur.</p>1 aPerkin, Joshuah, S.1 aGido, K., B.1 aFalke, Jeffrey, A.1 aFausch, Kurt, D.1 aCrockett, Harry1 aJohnson, Eric, R.1 aSanderson, John  uhttps://www.pnas.org/content/114/28/7373