Recovery of Salt Marsh Invertebrates Following Habitat Restoration: Implications for Marsh Restoration in the Northern Gulf of Mexico

Recovery following salt marsh restoration in the northern Gulf of Mexico is investigated using meta-analysis for two salt marsh indicator invertebrates, the periwinkle snail (Littoraria irrorata) and amphipod crustaceans (Amphipoda). These invertebrates serve key marsh ecosystem functions including facilitating nutrient cycling and serving as prey for larger ecologically and economically important species. Recovery of periwinkles in restored marshes compared to reference sites is quantified by progression in population density and, because the species is long-lived (~ 10 years), in terms of biomass added per unit area each year following restoration. Amphipods are shorter-lived with high annual turnover; thus, recovery through time is estimated by the density of individuals rather than by biomass. The results of the analyses indicate progressive periwinkle recovery to equivalence with reference systems by year 4 in terms of density and year 6 with respect to annual biomass addition, while amphipod densities do not fully recover in the first 20 years following restoration. Although periwinkle recovery in terms of annual biomass addition reaches equivalence by year 6, the development of an age class structure characteristic of reference marshes would likely take longer because of the relatively long lifespan for this species. In addition to providing insight into the benefits of salt marsh restoration in the northern Gulf of Mexico, the approach described can be applied more generally to restoration scaling in a natural resource damage assessment context.