Invertebrate zoogeomorphology: A review and conceptual framework for rivers

Abstract

Invertebrates are important sediment engineers, making up for their small body size with abundance and behavioral diversity. However, despite the recognized importance of invertebrates as sediment engineers in terrestrial and marine environments, zoogeomorphology in rivers has primarily considered larger taxa, such as fish and beaver. This article reviews the zoogeomorphic effects of invertebrates in freshwater habitats, with a focus on rivers. To better synthesize current zoogeomorphic research and to help guide future studies we build a conceptual model considering biotic (behavior, abundance, body size, life history, and species invasions) and abiotic (geophysical energy and sediment grain size) controls on the direction and magnitude of zoogeomorphology. We also incorporate invertebrate engineers into conceptual sediment entrainment models, to understand their geomorphic role in the context of hydraulic power and sediment size. We structure our review around invertebrate behavior as a key control on whether invertebrates have a sediment destabilizing or stabilizing impact. Invertebrate zoogeomorphic behavior are diverse; the majority of research concerns bioturbation, a result of locomotion, foraging, and burrowing behaviors by many taxa. Similarly, burrowing into bedrock by a caddisfly and non-biting midge larvae promotes bioerosion. Attachment to the substrate, (e.g., silk nets by caddisfly larvae or byssal threads by some mussels) can stabilize sediment, providing bioprotection. Bioconstructions (e.g., caddisfly cases and mussel shells) may have either stabilizing or destabilizing effects depending on their density and abiotic context. Interactions between lotic invertebrates and fluvial processes are complex and understudied, requiring further research across a greater range of taxa, behaviors, and spatiotemporal scales.

Aquatic insect bioconstructions modify fine-sediment entrainment and mobility

“…The Shields diagram (Shields, 1936) provides a useful means to compare the effects of different organisms on critical entrainment thresholds (following Mason & Sanders, 2021) and is commonly used to non-dimensionalize entrainment thresholds (Yang et al, 2019). Shields parameter (τ * 𝑐 ) was calculated according to Equation 8, for cases and loose sediment of each species:…”

“…For example, spawning salmon are estimated to contribute almost half of bedload transport in four British Columbia stream (Hassan et al, 2008) and may influence river evolution at the landscape scale (Fremier et al, 2018). Whilst fluvial zoogeomorphic research has focussed on larger taxa, small animals may have equally significant zoogeomorphic effects (Mason & Sanders, 2021).…”

“…The zoogeomorphological importance of insects is well recognised in marine and terrestrial environments (Bétard, 2021, Groom, 2021, but less is known about how they affect sediment processes in rivers. Nevertheless, aquatic insects can have substantial effects on the entrainment and mobility of sediment (see review: Mason & Sanders, 2021). Similar to fish and crayfish, insects may bioturbate sediment via locomotion and foraging activities.…”

Aquatic Insect Bioconstructions Modify Fine‐Sediment Entrainment and Mobility

“…For example, spawning salmon are estimated to contribute almost half of bedload transport in four British Columbia stream (Hassan et al., 2008) and may influence river evolution at the landscape scale (Fremier et al., 2018). Whilst fluvial zoogeomorphic research has focused on larger taxa, small animals may have equally significant zoogeomorphic effects (Mason & Sanders, 2021).…”

“…The zoogeomorphic importance of insects is well recognised in marine and terrestrial environments (Bétard, 2021; Groom, 2022), but less is known about how they affect sediment processes in rivers. Nevertheless, aquatic insects can have substantial effects on the entrainment and mobility of sediment (see review: Mason & Sanders, 2021). Similar to fish and crayfish, insects may bioturbate sediment via locomotion and foraging activities.…”