Consumer movement dynamics as hidden drivers of stream habitat structure: suckers as ecosystem engineers on the night shift

Ecosystem engineers engineering can control the spatial and temporal distribution of resources and movement by engineering organisms within an ecosystem can transport mobilize resources across boundaries and distribute engineering effects. Movement patterns of fishes can cause physical changes to stream aquatic habitats though nesting or feeding, both of which often vary in space and time. Here we present evidence of ecosystem engineering by the Sonora sucker (Catostomus insignis), a dominant fish in streams of the southwestern United States, and show how cryptic nocturnal movement patterns and bioturbation activities control heterogeneity in benthic substrates, and in sediment and carbon export. Sonora suckers exhibit distinct diel movement patterns, spending daylight hours in refuge habitats (typically deep pools) while moving into shallow habitats at night to feed. Feeding by suckers creates substantial disturbance in soft sediments that are patchy in space and time. These disturbances moved up to 2.4 × 104 cm3 of sediment per square meter per week in locations that are up to hundreds of meters away from sucker daytime refuges. The diel cycles in feeding activity (i.e., nocturnal digging in benthic substrates) caused nighttime pulses in suspended sediment that comprised up to 32% of the daily suspended load and organic matter transport of a stream reach. During the daytime, this particulate transport settles in habitats beyond the location of the initial disturbance, thus redistributing both sediment and organic matter. Our data indicate that cryptic movement by ecosystem engineers can distribute their effects in space and time generating heterogeneity in resources and suggest that habitat modifications restricting consumer movement may alter the impact of engineering activities.Each dataset has an associated _readme file which provides details about column headers and methodology. divotdensity - weekly estimates of ambient divot density and volume divotfill - estimates of the consequences of divot formation for capture of organic matter and colonization by invertebrates portabletelemetry - locations of tagged fish within the 6km study reach sedimenttransport - estimates of daily sediment transport and fish activity within the reach stationaryantennadetections - fish detections within focal habitat providing timing and location of diel movements taggedfish - tag id, species, size, and weight information for tagged fish (needed to interpret portabletelemetry and stationaryantennadetections datasets) washertransects - estimates of daily patch scale disturbance of soft sediments by fish Funding provided by: National Science FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000001Award Number: 0807413Funding provided by: National Science FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100000001Award Number: DGE 022165