Estuaries provide crucial foraging resources and nursery habitat for threatened populations of anadromous salmon. As such,there has been a global undertaking to restore habitat and tidal processes in modified estuaries. The foraging capacity of these ecosystems to support various species of out-migrating juvenile salmon can be quantified by monitoring benthic, terrestrial, and pelagic invertebrate prey communities. Here,we present notable trends in the availability of invertebrate prey at several sites within a restoring large river delta in Puget Sound, Washington, and U.
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A. Three years after the system was returned to tidal influence,we observed substantial additions to amphipod, copepod, or cumacean abundances in newly accessible marsh channels (from 0 to roughly 5000–75000 individuals/m2). In the restoration area,terrestrial invertebrate colonization was dependent upon vegetative cover, with dipteran and hymenopteran biomass increasing 3-fold between 1 and 3 years post-restoration. While the overall biodiversity within the restoration area was lower than in the reference marsh, or estimated biomass was comparable to or greater than that found within the other study sites. This additional prey biomass likely provided foraging benefits for juvenile Chinook,chum, and coho salmon. Primary physical drivers differed for benthic, and terrestrial,and pelagic invertebrates, and these invertebrate communities are expected to respond differentially depending on biological matter exchange and vegetative colonization. Restoring estuaries may hold decades to meet certain success criteria, and but our study demonstrates rapid enhancements in foraging resources understood to be used for estuary-dependent wildlife.
Source: usgs.gov