Silk‐producing stream insects and gravel erosion: Significant biological effects on critical shear stress

Statzner, Bernhard; Arens, Marie-Francoise; Champagne, Jean‐Yves; Morel, R.; Herouin, Eric

doi:10.1029/1999wr900196

Cited by 87 publications

(112 citation statements)

References 59 publications

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“…The combined field and flume experiments described here support the findings of earlier work in this area (Statzner et al, 1999;Cardinale et al, 2004) and extend that work in two important ways. First, we have established that there are elevated thresholds of incipient motion for fine gravels that are colonised in a natural river setting as distinct from gravels seeded with larvae in small, experimental channels.…”

Section: Discussionsupporting

confidence: 78%

“…In general, these results support the findings of earlier work (Statzner et al, 1999;Cardinale et al, 2004), but they also extend that work in two important ways: we have established elevated thresholds of incipient motion for fine gravels that have been colonised at natural densities and under natural stream conditions; and we have measured caddisfly impact relative to both laboratory and field-conditioned controls.…”

Section: Discussionsupporting

confidence: 77%

“…There is no evidence that by covering and by bonding together surface grains, biofilm offer protection from the flow and increased entrainment stresses. There is some evidence that biofilms are not effective in stabilising grains greater than 2 mm in diameter (Heinzelmann, 1992;Statzner, 1999) and the muddy biofilm present on our fine-gravels was quickly eroded in the flume at low-flow stages, leaving the underlying grains exposed to the flow.…”

Section: The Relative Importance Of Hydropsychidae Larvae and Other Cmentioning

confidence: 99%

“…In addition, some silk-producing, caseless, caddisfly larvae can stabilise bed sediments in the 2-8 mm size range (Cardinale et al, 2004) by constructing silk nets for feeding galleries (Alstad, 1987a;1987b;Statzner & Bretschko, 1998;Edler & Georgian, 2004;Brown et al, 2005) and retreats (Statzner et al, 1999). The silk binds fine sediment together thereby increasing critical entrainment stresses.…”

Section: Introductionmentioning

confidence: 99%

“…Statzner et al (1999) attempted to examine the influence of caddisfly on entrainment in natural settings, but interpretation of their results was complicated by flood disturbance during the experiment. Takao et al (2007) found that filter-feeding caddisfly biomass was correlated to clast stability; however, this does not imply that these clasts had been engineered, because filterfeeding caddisfly are known to live preferentially in stable areas due to their sedentary life style.…”

Section: Introductionmentioning

confidence: 99%

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Stabilization of fine gravels by net‐spinning caddisfly larvae

Johnson

Reid

Rice

et al. 2009

Earth Surf Processes Landf

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We examined the impact of Hydropsychidae caddisfly larvae on the incipient motion of two sizes of narrowly graded fine‐gravel (4–6 and 6–8 mm). This impact was assessed relative to the collective impact of other abiotic and biotic processes that are potentially important conditioning agents of fine‐gravels. Trays of gravel were placed in the River Soar, Leicestershire, UK, where they were colonized to natural densities by caddisfly larvae. Identical trays that were surrounded by a 250 µm mesh were also deployed, preventing colonization but allowing field conditioning of sediments, including minor reworking of grains and biofilm development. After 21 days in the river, trays were removed to a laboratory flume where grain entrainment stresses were established. In addition to the colonized and conditioned treatments, critical shear stresses were measured for identical sediments that were not placed in the river (laboratory gravels). Gravels that were colonized by Hydropsychidae required significantly greater shear stresses for entrainment than conditioned trays (p ≤ 0·002), however, there was no significant difference between conditioned and laboratory gravels. This implies that the presence of caddisfly can be a more important influence on fine‐gravel stability than some conditioning processes. Shields parameter was compared across treatments and across the two gravel size‐fractions using two‐way ANOVA. No significant differences or interactions were observed, indicating that 4–6 mm gravel was stabilized to a similar degree as 6–8 mm gravel by conditioning and colonization processes. Our results extend earlier studies in two important ways: (1) entrainment stresses were established for fine gravels that were colonized at natural densities, under natural stream conditions; and (2) the caddisfly effect was measured relative to both field‐conditioned and unconditioned laboratory controls. The temporal and spatial distribution of silk‐spinning caddisfly larvae suggests that they have the potential to influence fine‐sediment mobility in many rivers, worldwide. Copyright © 2008 John Wiley & Sons, Ltd.

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Section: Discussionsupporting

confidence: 78%

Section: Discussionsupporting

confidence: 77%

Section: The Relative Importance Of Hydropsychidae Larvae and Other Cmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Stabilization of fine gravels by net‐spinning caddisfly larvae

Johnson

Reid

Rice

et al. 2009

Earth Surf Processes Landf

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2000

Hydrological Processes

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A mechanistic model linking insect (Hydropsychidae) silk nets to incipient sediment motion in gravel‐bedded streams

et al. 2014

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Plants and animals affect stream morphodynamics across a range of scales, yet including biological traits of organisms in geomorphic process models remains a fundamental challenge. For example, laboratory experiments have shown that silk nets built by caddisfly larvae (Trichoptera: Hydropsychidae) can increase the shear stress required to initiate bed motion by more than a factor of 2. The contributions of specific biological traits are not well understood, however. Here we develop a theoretical model for the effects of insect nets on the threshold of sediment motion, τ * crit , that accounts for the mechanical properties, geometry, and vertical distribution of insect silk, as well as interactions between insect species. To parameterize the model, we measure the tensile strength, diameter, and number of silk threads in nets built by two common species of caddisfly, Arctopsyche californica and Ceratopsyche oslari. We compare model predictions with new measurements of τ* crit in experiments where we varied grain size and caddisfly species composition. The model is consistent with experimental results for single species, which show that the increase in τ * crit above the abiotic control peaks at 40-70% for 10-22 mm sediments and declines with increasing grain size. For the polyculture experiments, however, the model underpredicts the measured increase in τ * crit when two caddisfly species are present in sediments of larger grain sizes. Overall, the model helps explain why the presence of caddisfly silk can substantially increase the forces needed to initiate sediment motion in gravel-bedded streams and also illustrates the challenge of parameterizing the behavior of multiple interacting species in a physical model.

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Silk‐producing stream insects and gravel erosion: Significant biological effects on critical shear stress

Cited by 87 publications

References 59 publications

Stabilization of fine gravels by net‐spinning caddisfly larvae

Stabilization of fine gravels by net‐spinning caddisfly larvae

Current awareness

A mechanistic model linking insect (Hydropsychidae) silk nets to incipient sediment motion in gravel‐bedded streams

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