Patterns of macroinvertebrate production, trophic structure, and energy flow along a tallgrass prairie stream continuum

Abstract

We estimated benthic organic matter standing stocks, macroinvertebrate production, food-web structure, and stream metabolism along a longitudinal continuum of Kings Creek at Konza Prairie Biological Station in Kansas. Benthic macroinvertebrates were sampled for 1 yr from three stream reaches (grass, shrub, gallery forest). Total habitat-weighted production ranged from 9.1 g to 31.9 g ash-free dry weight m 22 yr 21 with the grass headwaters accounting for the highest production. Functional group contributions to production were similar along the continuum, with collector-gatherers (40-56% of total) and predators (23-38%) dominating all reaches. Detrital pathways appeared to account for most energy flow in all reaches, and all reaches were net heterotrophic on all dates when metabolism was measured, except for the grass headwater reach in spring. Predators were wellrepresented and consumed 65-107% of total macroinvertebrate production, whereas scrapers (11-15%), shredders (2-4%), and filterers (, 1%) consumed relatively small percentages of available resources. Dominance of predators suggested top-down controls are important in this system. However, changes in energy flow through other groups reflected longitudinal variation in resource availability. This prairie stream continuum conforms to some predictions of conceptual stream continua models, but biotic interactions, which are often not considered, may override some predicted responses to changes in the physical template.

Secondary production of caddisflies reflects environmental heterogeneity among tropical Andean streams

“…5 Monthly sizefrequency histograms where class sizes were determined for each reach: a Pajonal; b Polylepis; and c Mixed forest and n is the number of individuals measured the topographically complex Ecuadorian Andes. This heterogeneity in stream characteristics likely played a key role in the high variability we saw in both Helicopsyche secondary production and life history attributes, similarly to findings from the temperate zone on differential local habitat drivers of production in various stream insects (e.g., Grubaugh et al, 1997;Robinson & Minshall, 1998;Plague et al, 1998;Whiting et al, 2011). As we hypothesized, secondary production of this grazer taxon positively correlated with periphyton biomass overall, and life history attributes varied across the sampled reaches with some evidence for seasonality associated with annual precipitation patterns.…”

Abrupt biological discontinuity in a small Michigan (USA) stream due to historical riparian canopy loss

“…In the case of benthic macroinvertebrates, the difficulty of sampling microhabitats (e.g., large woody debris) representatively may lead to samples that are non-representative of the overall assemblage. In our study, the ease of collecting gathering collectors in Hess samples taken from shallow riffles led to samples dominated by these ubiquitous and non-informative taxa, thus decreasing the 'signal' relative to the 'noise' of a sample (Cao and Hawkins 2011;Whiting et al 2011). In the case of adult caddisflies, the lack of response from the scraper functional group has been noted in previous studies (Houghton 2006(Houghton , 2007.…”

The Stream Biome Gradient Concept: factors controlling lotic systems across broad biogeographic scales

“…Studies of stream invertebrate communities in North American desert (e.g., Fisher 1986, Stanley et al 1994), grassland (e.g., Fritz and Dodds 2002, Stagliano and Whiles 2002, Whiting et al 2011, and forested (e.g., Gladden and Smock 1990) regions suggest that relatively few taxa are unique to grassland streams, with some notable exceptions, such as the Platte River caddisfly (Ironoquia plattensis) (Whiles et al 1999) and Scott riffle beetle (Optioservus phaeus) (White 1978). Aquatic invertebrate endemism can be high in arid regions, where species are often associated with isolated springs or wetlands (Whiteman and Sites 2008).…”

“…However, estimates of invertebrate abundance, biomass, and production from prairie (e.g., Stagliano andWhiles 2002, Whiting et al 2011) and desert (e.g., Fisher and Gray 1983) streams often exceed those from their forested counterparts, a pattern noted by Benke (1993) in a meta-analysis of stream invertebrate production studies. For example, invertebrate production in Sycamore Creek, a warm Sonoran Desert stream, was estimated at 121 to 135 g dry mass (DM) m -2 y -1 (Fisher et al 1982), compared to estimates from temperate grassland streams, which are quite variable, but generally fall in the range of ∼8 to 50 g DM m -2 y -1 (e.g., Huryn 1998, Whiting et al 2011. Estimates of secondary production from Arctic tundra streams were orders of magnitude lower, ranging from 0.8 to 2.2 g DM m -2 y -1 (Harvey et al 1998).…”

“…Studies in grassland systems suggest that both top-down and bottom-up processes regulate foodweb structure (Huryn 1998, Stagliano and Whiles 2002, Nyström et al 2003. Where dense canopy cover is lacking, reliance on autotrophic production should be greater (Whiting et al 2011). Moreover, primary consumers should be favored in intermittent reaches of desert and grassland streams because the recovery of the microbial autotrophic food sources is rapid.…”