A short‐term home with long‐term potential: temporary aquatic habitat additions to support macroinvertebrate colonisation

ABSTRACT River restoration projects often focus on water quality and riparian vegetation, assuming this will result in direct improvements to ecological health. However, successful recovery of aquatic communities likely requires additional steps targeting habitat beneath the water surface. We trialled the addition of simple, instream habitat units as a practicable short‐term restoration tool targeting aquatic macroinvertebrate communities. Habitat units were built from readily available, biodegradable materials. They were deployed at three sites around Auckland with differing hydromorphology and surrounding land use, enabling evaluation of both the efficacy of installation and impacts on biodiversity. Additional macroinvertebrate sampling (Surber and drift collection) was conducted to assess community responses following habitat unit addition. All habitat units showed significant increases in macroinvertebrate densities and taxon richness compared to the surrounding existing habitat. However, the most marked increases in abundance may be attributable to inundation of habitat units by pre‐existing tolerant taxa capitalising on the increase in available habitat, rather than successful colonisation by additional taxa. This work highlights the potential of small‐scale, short‐term habitat additions as a restoration tool. This approach facilitates evaluation of restoration potential, informing design and implementation of more permanent restoration measures in future.