Macroinvertebrate production and food web structure along a tallgrass prairie stream continuum

Conceptual models of stream continua predict that energy flow and consumer functional structure change predictably with physical attributes of a stream.  We estimated macroinvertebrate production and quantified energy flow and food web structure along a longitudinal continuum of Kings Creek, a tallgrass prairie stream draining the Konza Prairie Biological Station in Eastern Kansas. Riparian vegetation along the continuum ranged from grassy headwaters, to shrubby mid-reaches, to lower reaches with gallery forest. Total habitat-weighted production ranged from 32.1 g ash-free dry mass (AFDM) m^-2 y^-1 in the grassy headwater reach to 9.3 g AFDM m^-2 y^-1 in the shrubby reach, and was 19.8 g AFDM m^-2 y^-1 in the gallery forest. Functional group contributions to production were similar along the continuum, with collector-gatherers (39%-63%) and Predators (26%-47% of total) dominating all reaches. Quantitative food webs indicated detrital pathways were dominant in all reaches, with collectors and scrapers accounting for most energy flow through primary consumers. Predators were well represented and consumed 75% - 135% of total macroinvertebrate production, indicating they may be food limited where 1° consumers have lower turnover rates. Although functional structure was fairly similar among reaches, energy flow among groups reflected longitudinal changes in resource availability.