The zoogeomorphology of case‐building caddisfly: Quantifying sediment use

Abstract

Caddisfly (Trichoptera) larvae are an abundant and widespread aquatic insect group characterized by the construction of silk structures, including nets and cases. Case‐building caddisfly have the potential to modify the sorting and mobility of sand and fine gravel via: (1) case construction, resulting in altered sediment properties; (2) transporting sediment incorporated into cases over the river bed; and (3) changing the structure of river beds via burrowing activity. To investigate these mechanisms, it is necessary to understand the mass, size distribution and spatial variability of sediment use by case‐building caddisfly larvae. We quantified the mineral sediment used by individuals and communities of case‐building caddisfly in 27 samples, from three sites on a gravel‐bed stream. The mass and size distribution of sediment in individual cases varied between taxa (mass = 0.001–0.83 g, D50 = 0.17–4 mm). The mean mass of sediment used by the caddisfly community was 38 g m−2 and varied locally. Sediment use was predominantly coarse sand (D50 = 1 mm). 64% of sediment use was attributable to Agapetus fuscipes (Glossosomatidae). Due to within‐species variability in case mass, the abundance of most taxa, including A. fuscipes, was only weakly associated with the mass of sediment used by this species, at the river scale. Whilst the caddisfly community used a small percentage of the total sediment available (average 2.99% of the 1–1.4 mm size fraction), A. fuscipes used more fine sediment in their cases at sites where it was more available. Despite variability in local habitat, all sites supported diverse case‐building caddisfly communities utilizing mineral sediment. Consequently, geomorphological effects of case‐building caddisfly are potentially widespread. The results provide novel insights into the specific grain sizes and quantities of fine sediment used by caddisfly larvae, which represents an important step towards understanding their zoogeomorphic activities. © 2019 The Authors. Earth Surface Processes and Landforms Published by John Wiley & Sons Ltd.

PVC and PET microplastics in caddisfly (Lepidostoma basale) cases reduce case stability

“…Caddisfly larvae use various materials from their surroundings to build cases which facilitate respiration and serve as camouflage and physical protection (Williams et al 1987;Johansson 1991;Nislow and Molles 1993;Otto and Johansson 1995;Wissinger et al 2004). For case construction, caddisfly larvae spin adhesive silk and, depending on caddisfly species, collect sediment grains or/and plant pieces (Mackay and Wiggins 1979;Mason et al 2019). Sometimes, caddisfly larvae build so-called emergency cases for immediate protection which consist of loosely connected building materials and which cover the larva before it builds a more durable e.g.…”

Biogeomorphology, quo vadis? On processes, time, and space in biogeomorphology

“…Mason et al . (2019) and Rice et al . (2019) explore the potential of case‐building caddisfly larvae and fish feeding behaviour in changing in‐channel sediment transport, while Grenfell et al .…”

“…Mason et al . (2019) collected data on the mineral sediment use of caddisfly larvae in river riffles. Different species used different ranges of grain sizes (mostly coarse sand and fine gravel) and might influence river processes by directly affecting the distribution and mobility of this sediment size range.…”

“…Yet, many contributions within this issue highlight that our understanding of biogeomorphic feedback systems is incomplete and, importantly, differs depending on the scale considered. For the smallest scales, a mechanistic understanding is established for some feedback systems (Grenfell et al ., 2019; Mason et al ., 2019) but many other feedback systems at the smallest scales remain unresolved to date (e.g. microbial effects on sediment dynamics, microbial effects on extraterrestrial bodies).…”

Insects as zoogeomorphic agents: an extended review

“…Digging behaviour for pupating is reported for a wide range of insect orders, including Coleoptera (dung beetles, scarabs, chafers, weevils), Diptera (flies), Mecoptera (scorpionflies) and Megaloptera (alderflies, dobsonflies, fishflies). In the Trichoptera order (caddisflies), larvae burrow and pupate into the bottom sediment of streams, and have direct and indirect geomorphic effects by modifying the hydraulic properties of bed material and the permeability of hyporheic zones (Johnson et al ., 2009; Mason et al ., 2019). Some hemimetabolous insects (i.e.…”