Sedimentation affects emergence rate of host fish fry in unionoid mussel streams

Abstract

Free-living, sympatric sedentary life stages of hosts and parasites are often adapted to similar environmental conditions. When the environment where these life stages occur is disturbed, both species can decline, causing strong negative effects on the parasitic species. For the highly threatened unionoid mussels with their larval parasitic life stage on fish, habitat degradation may simultaneously affect the conditions for the sedentary host fish eggs and the juvenile mussels in the sediment. This study provides novel information on the effect of sedimentation on the emergence rate of yolk sac fry, and its relation to mussel recruitment in two drainage basins, and is exemplified by the brown trout Salmo trutta, host fish for the threatened freshwater pearl mussel Margaritifera margaritifera. The results imply that turbidity and sedimentation can reduce the survival of trout eggs and yolk sac fry emergence rate regardless of trout strain and drainage basin. The results further suggest that low yolk sac fry emergence rates reduce the potential for mussel infestation and recruitment. The results indicate a year round negative effect of sedimentation, having strong and combined direct and indirect effects on juvenile mussel recruitment. Conservation measures that reduce anthropogenic sediment transportation into streams are a key factor for the conservation of mussels and their host fish.

One informs the other: Unionid species at risk and benthic macroinvertebrate community monitoring data are complementary

“…For example, fine sediment is a major stressor to both species groups. Benthic macroinvertebrates are impacted to the degree that sensitive species are eliminated (Burdon et al 2013), while fine sediment is known to adversely affect mussel feeding (Tuttle-Raycraft et al 2017), as well as reproduction (Gascho Landis et al 2013;Österling 2019). Hence restoration actions that increase overall macroinvertebrate diversity will likely also benefit mussels.…”

Effects of different weed cutting methods on physical and hydromorphological conditions in lowland streams

“…The sediment traps were deployed immediately downstream of the stream reach subjected to weed cutting at the time of initiated weed cutting and were removed at the end of the weed cutting. The sediment traps were modified versions of Rubin boxes previously applied to evaluate effects of fine sedimentation rates on trout egg hatching success (Rubin, 1995;Österling, 2018). The trap (height 25 cm, diameter 10 cm) walls and bottom consisted of polypropylene, and each trap was filled with round and washed gravel and stones to maintain the trap in position.…”