Investigating a mitigation strategy for acidic sediment conditions in support of First Nation Bivalve restoration initiatives : the effect of shell hash on porewater pH and carbonate saturation states in Burrard Inlet, British Columbia, Canada

Abstract

Climate change related impacts threaten calcium carbonate dependent species, such as bivalve shellfish. Coastal sediment acidification may have disproportionate effects on bivalves. Shellfish are ecologically, economically, and socially significant in the Pacific Northwest. This research was guided by First Nation habitat restoration objectives and Indigenous science. Using field studies and microcosm experiments, we investigated the effect of shell treatments on sediment porewater conditions in Burrard Inlet, Canada. Porewater pH and aragonite saturation states (Ωarg) were evaluated under different tidal conditions and pH treatments. Significant differences were found in porewater acidity and Ωarg between sites, tidal conditions, and pH treatments. There was no consistent shell treatment effect on porewater pH or Ωarg. Augmenting coastal sediment with shell material has many documented benefits. Based on the results, shell treatments are not recommended as an effective mitigation for acidic sediment conditions in support of First Nation shellfish habitat restoration objectives in Burrard Inlet.