Crayfish as geomorphic agents and ecosystem engineers: Biological behavior affects sand and gravel erosion in experimental streams

Abstract

Effects of animals on the transport of solids (e.g., sediments) can modify earth-surface processes and landforms (role as geomorphic agents) and resources for other organisms (role as ecosystem engineers). Therefore, we studied the impact of crayfish (Orconectes limosus) behavior on sand-gravel erosion and bottom habitat over riffle-pool sequences in experimental streams. We manipulated the availability of crayfish food and refugia. Refugia availability had clear effects on overall crayfish activity. The establishment of dominance hierarchies among the crayfish produced patterns in crayfish activity that differed between riffles and pools. Crayfish activity significantly affected sand and gravel erosion. High local sediment erosion averaged ഠ2.8 (riffles) and ഠ1.4 (pools) kg dry weight mϪ1 when crayfish hierarchies were established and refugia were available. Removing the refugia increased these rates to ഠ4.0 (riffles) and ഠ3.2 (pools) kg dry weight m Ϫ2 d Ϫ1. This direct erosion caused by crayfish should be lower than that caused by floods. Crayfish distinctly (1) increased bedform roughness (riffles), (2) decreased sand dune height (pools), (3) shifted the transition between gravel (riffles) and sand (pools) downstream, (4) decreased sand in gravel interstices (riffles), (5) decreased filamentous algae growth on gravel (riffles), and (6) decreased biofilm cover on sand dunes (pools). These sediment changes due to crayfish activity at baseflow should have opposite effects on sediment erosion during subsequent floods. Crayfish impact on physical habitat at baseflow could largely affect population and community structure of the benthos, as well as egg survival of gravel-breeding fish.

Influence of temperature on surface sediment disturbance by freshwater fish: a microcosm experiment

“…Third, it should be noted that our experiment was limited to three fish species, thus neglecting other fish that are known to be active streambed sediments bioturbators either by feeding or swimming (e.g., the barbel Barbus barbus L.1758: Pledger et al, 2014; the gudgeon Gobio gobio L.1758: Statzner et al, 2003b;Statzner and Sagnes, 2008;larval lamprey: Shirakawa et al, 2013) or nest digging (e.g., salmonids: De Vries, 2012), but also other zoogeomorphic animals such as crayfish (e.g., Statzner et al, 2000) or benthic macro-invertebrates (e.g., De Nadaı¨- Monoury et al, 2013). Moreover, due to limited space, a single fish was placed into each aquarium preventing all complex biotic interactions known to affect bioturbating activities.…”

“…They could result simultaneously in waters with higher suspended solids and fine elements (e.g., organic detrital matter) concentrations, but lower fine sediment volumes (Statzner, 2012) in local places such as deposition areas. Fine sediment removal may subsequently affect negatively biological communities by reducing the establishment and presence of sessile or movement-limited insects (Pringle et al, 1993) and reducing bed biofilms (Statzner et al, 2000) that indirectly affect leaf decomposition processing. In lentic waters, turbidity could be hastened and concentrations in nutrients and organic material higher due to the resuspension of sediments to the water column through bioturbation by fish (e.g., Breukelaar et al, 1994;Matsuzaki et al, 2009), resulting subsequently in phytoplankton blooming and water eutrophication, already enhanced by warming (Jeppesen et al, 2010).…”

“…First, despite the innovative nature of this experiment in microcosms, it is a preliminary approach that deserves to be applied ex situ with more realistic stream flow conditions (e.g., flumes, larger sediment diameters; see such experimental designs in: Statzner et al, 2000;Pledger et al, 2014) or in situ, in both lentic and lotic systems. In streams, water flow can indeed hide the movement of particles due to bioturbation by invertebrates and small fish that have thus limited direct geomorphological implications (Statzner, 2012).…”

Temporal dynamics of seston: A recurring nighttime peak and seasonal shifts in composition in a stream ecosystem

“…Bioturbation is known to affect ecosystem function in marine ecosystems, but, recently, it has received attention in stream and river ecosystems (Moore 2006). Studies of freshwater aquatic ecosystems in various biomes have identified nocturnal species of macroinvertebrates and amphibians as drivers of bioturbation (Zanetell and Peckarsky 1996;Statzner et al 2000). Predaceous stoneflies increase sediment suspension from the streambed while searching the rocks and sediments for prey (Zanetell and Peckarsky 1996).…”

Conception Des Dispositifs De Franchissements Pour La Faune Amphidrome (Crevettes Et Poissons) Des Cours d'EAU Antillais : Une Revue.

“…Les chaînes alimentaires y sont en effet très courtes et la faune amphidrome représente la majorité de la biomasse (COVICH et McDOWELL, 1996 ;PRINGLE, 1997). De part leurs diverses activités (bioturbation, alimentation, déplacements), certaines crevettes et certains poissons ont un effet spectaculaire sur la biomasse d'algue, sur la structure des communautés notamment celles d'insectes ainsi que sur le transport solide des particules fines (rôle d'organismes ingénieurs sensus JONES et al, 1994 ;STATZNER et al, 2000) (CHACE et HOBBS, 1969 ;PRINGLE et al, 1993 ;PRINGLE et BLAKE, 1994 ;PRINGLE, 1996 ;PRINGLE et HAMAZAKI, 1997). La conservation de la faune amphidrome en amont des ouvrages est donc essentielle pour garantir l'intégrité des écosystèmes aquatiques (PRINGLE et SCATENA, 1999a), gage d'une eau de bonne qualité (YOUNG et al, 1994).…”