Facilitating the recovery of insect communities in restored streams by increasing oviposition habitat

Please join us for the next edition of the National Conservation Training Center’s Conservation Science Webinar Series.
Panelist: Samantha Jordt
Stream restoration is a necessary practice to address the degradation of waterways globally. Yet, current restoration practices rarely result in the reestablishment of aquatic insect communities. In both terrestrial and marine restored sites, recruitment limitation has been identified as a contributing factor in failed biological recolonization and has been suggested as limiting aquatic insect establishment in stream restoration as well. Here, we focus on one aspect of recruitment into streams, aquatic insect egg-laying. An estimated three-quarters aquatic insects require emergent instream habitat such as rocks or wood to attach their eggs and availability of egg-laying habitat has been shown to limit egg mass abundance. In a census of 50 m long areas of ten restored streams and three reference streams, both rock and egg mass densities were lower in restored streams than reference streams and rocks were also more likely to roll in restored streams. After experimentally increasing oviposition habitat in five out of ten restored streams, egg mass density and richness per stream area increased in restored-treated streams. These results indicate that restored streams were limited by oviposition habitat and possibly stability but minor increases in egg-laying habitat can alleviate one recruitment limitation. However, larvae in the four egg laying taxa did not respond to treatment indicating there may be additional recruitment or post recruitment barriers to aquatic insects. This experimental approach to accelerating biological restoration in restored streams is one example of how multidisciplinary collaboration and intersections in science may illuminate missing linkages and improve ecological restoration.
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