Effects of gravel augmentation on macroinvertebrate assemblages in a regulated California river

  • Published source details Merz J.E. & Chan L.K.O. (2005) Effects of gravel augmentation on macroinvertebrate assemblages in a regulated California river. River Research and Applications, 21, 61-74.


This study is summarised as evidence for the following.

Action Category

Other biodiversity: Restore habitat along watercourses

Action Link
Mediterranean Farmland
  1. Other biodiversity: Restore habitat along watercourses

    A replicated, before-and-after study in 1996–2000 at seven salmon-spawning sites along the lower Mokelumne River, in the Central Valley, California, USA, found more macroinvertebrates, 10 weeks after gravel addition, compared to before gravel addition. Invertebrates: Similar numbers of macroinvertebrate species and individuals were found in sites with or without gravel addition, by week 6 (0–30 vs 21 species; 350,000 vs 300,000 individuals/m3). However, by week 10, more individuals were found in sites with gravel addition (290,000 vs 150,000 individuals/m3). Methods: Gravel was added to seven sites, between 15 August and 15 September, in 1996–2000 (different sites in different years, approximately 30 x 65 m sites, each of which was approximately 1–2% of remaining Chinook salmon Oncorhynchus tschawytscha spawning habitat). Macroinvertebrates were collected from the substrate (15 cm depth) with a stream sampler (bottom open area: 0.086 m2) and a dolphin bucket (368 μm) in flowing water (0.25–1 m/s, <60 cm depth), one week before and every two weeks after gravel addition, in September–January 1996–2000.


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