Sand Erosion by Mobile Predaceous Stream Insects: Implications for Ecology and Hydrology

Abstract

Despite increasing knowledge of the ability of keystone animal species (“ecosystem engineers”) to change their physical environment, there is little and inconsistent evidence that benthic invertebrates affect the erosion of bottom material in streams. Therefore we designed field stream experiments and observations to investigate the effect of mobile predaceous stonefly (Dinocras cephalotes) larvae on sand erosion. When short of prey, the stoneflies erode sand from stream riffles thereby deepening the interstices between cobbles. On the basis of reasonable assumptions, we speculate that Dinocras has an erosion potential of about 200–400 kg sand m−2 yr−1 at natural population densities under favorable flow conditions. We consider the possible implications of the bioturbation potential of stream invertebrates for ecology (habitat quality and disturbance) and hydrology (sand transport and stability of coarse stream bottoms), which call for joint research on this novel role invertebrates play in the functioning of stream ecosystems.

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

“…bottom material by 30% (North America [Zanetell and Peckarsky, 1996]) to 75% (Europe [Statzner et al, 1996]). Killing the stream insects with insecticides decreases the export of inorganic particles from a small stream catchment by 75% compared with neighboring control catchments [Wallace et al, 1993].…”

“…Finally, benthic microalgae stabilize sand finer than 2 mm so that the critical shear stress may be increased by a factor of 30 for very small (0.2 mm) sand and very high algal biomass [Heinzelmann, 1992]. Thus small benthic stream organisms significantly affect the transport of solids, comparably to the benthos of marine environments [Heinzelmann and Wallisch, 1991], and thereby also alter the habitat for other organisms (ecosystem engineering [Jones et al, 1994;Flecker, 1996;Statzner et al, 1996]). However, these biological effects concern the transport of fine sediments, while the potential impact of small organisms on the transport of coarser particles has not yet been considered.…”

Le Colmatage Minéral Du Lit Des Cours D’eau : Revue Bibliographique Des Mécanismes Et Des Conséquences Sur Les Habitats Et Les Peuplements De Macroinvertébrés.

“…La faune aquatique peut influencer localement l'arrangement des sédiments lors d'activités comme la reproduction (KONDOLF et al, 1993), les combats pour occuper l'espace ou les déplacements liés à la recherche de nourriture (STATZNER et al, 1996. Lors de la reproduction, les Salmonidae nettoient les zones de ponte et expulsent environ 30-35 % des sédiments < 1 mm lors de la formation de la frayère (KONDOLF et al, 1993).…”

“…Lors de la reproduction, les Salmonidae nettoient les zones de ponte et expulsent environ 30-35 % des sédiments < 1 mm lors de la formation de la frayère (KONDOLF et al, 1993). Des organismes de plus petite taille tels que les larves de Dinocras cephalotes (plécoptère) réduisent localement la quantité de sédiments fins comblant les interstices de 30 % (ZANETELL et PECKARSKY, 1996) à 75 % (STATZNER et al, 1996) lors de la recherche de proies. DANIELOPOL (1984) suggère que la digestion de la matière organique fine ou du biofilm bactérien par les invertébrés pourrait réduire les effets du colmatage dans la zone hyporhéique et maintenir élevée la conductivité hydraulique du milieu.…”

Hydraulic habitat preferences of the torrential mayfly Epeorus longimanus (Ephemeroptera: Heptageniidae): the ecological importance of near-bed flows

“…The predatory activities of the mobile stonefly Dinocras cepha/otes also result in the erosion of fine sediments (Statzner et al 1996). The ecological importance of this stonefly approaches that of a keystone species (Jones et al 1994 ), due to the large influence this species has on erosional processes in stream riffle habitats.…”