Moving into the Hyporheic Zone

Climate change is causing some alpine streams to change from always flowing to flowing only part of the time. This is a challenge that the bugs in those streams have not had to face, but the might have a way out: hunkering down in the hyporheic zone, a subsurface component of the stream. By waiting out drought in this new environment, the bugs might be able to come back and resume life as normal when conditions are more favorable.

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Sending ripples through environments: a new type of keystone species

Keystone species have ripple effects on the other organisms in their environments, but do any species have similar effects on the environment itself? The idea of a biogeomorphic keystone species captures this idea and, like that of keystone species, requires piecing together a complex web of interactions to understand the big picture. Two researchers in Kentucky present how two tree species have strong effects on their local stream environments, qualifying them as potential biogeomorphic keystone species.

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A sucker for ecosystem engineers

Sonoran suckers, like other ecosystem engineers like beavers or salmon, substantially influence the spatial and temporal distribution of their environment’s resources. These fish create divots in soft sediments during their nightly feeding rounds in shallow waters far from where they seek refuge during the day. This feeding and these divots contribute heavily to shaping patterns of aquatic insects and suspended sediment in the Gila River, establishing the suckers as important ecosystem engineers in the river.

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To bugs in streams, fine sediment is not so fine

Clearing land for agriculture often leads to decreased flow velocities and in increase in fine sediment additions in nearby streams. While many stream bugs rely on small fine sediments, too much of it can detrimentally affect them. Changes to flow velocities and inputs of fine sediment in affected streams are not always equal in magnitude, so an experiment was run to see the responses of aquatic macroinvertebrates to various combinations of flow and sediment conditions. The scientists found fine sediments negatively impacted almost all stream bugs and that low flows exacerbated the problem.

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