Meta-analysis of Nekton Recovery Following Marsh Restoration in the Northern Gulf of Mexico

Abstract To investigate regional patterns in marsh recovery following restoration, a meta-analysis of nekton densities at restored and reference marshes in the northern Gulf of Mexico (GOM) was conducted. Results were variable at both restored and reference sites, but general trends with respect to the age of the restored site were observed. Pooled together, mean total nekton density in restored marshes during the first 5 years following restoration was approximately 50% of reference marsh densities [95% confidence interval (CI): 26.6–93.0%]. Mean total nekton density in restored marshes in subsequent years (age of restored sites: 6 to 30 years) was approximately 73% of reference marsh densities (95% CI: 46.1–116.1%). Relative densities of crustaceans in restored marshes tended to be lower than in reference marshes during both the initial 5 years following restoration (mean = 36%; 95% CI: 16.6–76.7%) and in subsequent years (mean = 71%; 95% CI: 42.7–119.2%). Mean densities of fish species also tended to be somewhat lower in restored marshes than in reference marshes, but relative densities were highly variable during both the initial 5-year period (mean = 85%; 95% CI: 33.5–215.3%) and in subsequent years (mean = 77%; 95% CI: 39.3–152.7%). A generally increasing trend in total nekton and total crustacean densities was observed over the first 15 years following restoration; mean densities at restored sites were comparable to paired reference locations by approximately year 13. Findings from this study indicate that marsh restoration may not consistently result in nekton production similar to that of natural sites, particularly in the earlier years following restoration when baseline ecosystem processes are developing.