Wind dispersal and saltation effect on microinvertebrate propagules: A wind tunnel study

Abstract

Ephemeral wetland surfaces are preferential locations for wind erosion and repositories for resting stages (propagules) of aquatic invertebrates. Dormant propagules can disperse to new habitats via wind (aeolian transport, or anemochory). Wind transport of invertebrate propagules has been documented at local and regional scales, but prior laboratory wind tunnel tests of propagule anemochory neither replicated the predominant natural processes of wind erosion in drylands, saltation-sandblasting, nor determined the viability of experimentally wind-transported propagules. We used a soil saltation wind tunnel to test aeolian erosion, transport, and subsequent viability of propagules from seven aquatic invertebrate species. A propagule-bearing crusted soil surface was prepared, then abraded by saltating silica sand in the wind tunnel to emit aeolian sand and dust. Sediment was collected from three downstream sections of the wind tunnel, representing different transport distances in the environment, and propagules were quantified for each section by species. The wind-eroded material was rehydrated with sterile media to detect hatching of any propagules which survived the sandblasting. Although survival was much lower than in a control experiment without wind tunnel saltation treatment, and hatching rates were lower than those reported from undisturbed egg banks, viable individuals of all wind-tunnel-tested species were detected after hydration. Larger propagules settled closer to the source of entrainment than smaller propagules, indicating a shorter dispersal distance for larger propagules- although only short-distance anemochory may be necessary for dispersal across drainage basins. These results demonstrate that resting stages of many invertebrates can be wind-bombarded from natural surfaces along with sand and dust, dispersed into and transported through the atmosphere, and remain viable. Future investigations of anemochory of aquatic invertebrates from ephemeral waters should use appropriate wind tunnels to evaluate propagule and surface properties as potential adaptations for wind dispersion.