Groundwater declines are linked to changes in Great Plains stream fish assemblages

Area of Science:

• Ecology
• Hydrology
• Conservation Biology

Background:

• Groundwater pumping for agriculture significantly impacts freshwater ecosystems globally.
• Ecological consequences for stream fish assemblages due to groundwater depletion are understudied.
• The High Plains Aquifer in the United States is a critical water source facing depletion.

Purpose of the Study:

• To predict changes in Great Plains stream fish assemblages linked to groundwater pumping from the High Plains Aquifer.
• To assess the impact of groundwater depletion on stream habitat length and fish community structure.
• To project future changes in stream ecosystems under continued groundwater extraction.

Main Methods:

• Combined retrospective (1950-2010) and prospective (2011-2060) modeling.
• Utilized a multiscale framework analyzing regional and subwatershed scales.
• Modeled relationships between stream length, groundwater depth, and fish assemblage composition.

Main Results:

• Regional water development resulted in 154 barriers, increased groundwater depth, and 558 km of stream loss.
• Fish assemblages transformed from large-stream to small-stream species dominance.
• Subwatershed analysis showed consistent fish assemblage shifts with increasing groundwater depth.
• Barriers fragmented habitats, isolating fish populations.

Conclusions:

• Groundwater pumping leads to stream shrinking and homogenization of fish assemblages in the Great Plains.
• Future projections indicate continued stream loss and shifts in fish communities.
• Similar transformations are predicted globally with aquifer depletions.