Evaluating the effects of vertical relief on ecosystem service provision by restored oyster reefs

Date

2022-12

Authors

Sugla, Monisha

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Abstract

Oyster reef restoration has emerged as a management tool for maintaining oyster fisheries and ecological functions, often with different reef designs used to support different restoration objectives. Restoration managers in the Gulf of Mexico aim to maximize their return on restoration investments with project-specific goals ranging from habitat provision, faunal enhancement, and nitrogen regulation in oyster reef restoration. The goal of this study was to evaluate ecosystem service provision by restored reefs constructed as either high relief (~0.6 m) ‘mounds’ or low- relief (<0.08 m) ‘flats’. Measures of habitat provision, faunal enhancement, and nitrogen regulation were examined and compared among restored reef types and adjacent unrestored reef areas for 12 months after construction. Oyster density and sizes were monitored until 18 months after restoration. Reef mounds provide a higher ecological return on investment than reef flats. In terms of habitat provision, reef mounds produced 75% higher oyster density, 201% higher motile epifauna biomass, and 360% higher motile epifauna density per m2 than reef flats one year after construction. In terms of faunal enhancement, 1 m2 of reef mounds is expected to yield 63% higher additional production of resident fish and crustaceans compared to reef flats (1.8 kg y-1 vs. 1.1 kg y-1 ) over the functional lifetime of the reef. Estimates of nitrogen regulation (from denitrification, burial, harvest) provided by reef mounds were 395% greater and provided 103% greater cost equivalent value than those provided by reef flats one year after construction. Understanding differences in ecosystem service provision stemming from reefs constructed from similar amounts and type of material, but with differing relief, will allow resource managers to improve cost-efficiencies in future restoration projects.

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coastal resilience, ecosystem services, faunal enhancement, harvest resilience, oyster reef restoration, vertical height

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Attribution-ShareAlike 4.0 International

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