Multi-year persistence of beach habitat degradation from nourishment using coarse shelly sediments

• Published in: The Science of the total environment Vol. 487; pp. 481 - 492
• Main Authors: Peterson, Charles H., Bishop, Melanie J., D'Anna, Linda M., Johnson, Galen A.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15.07.2014; Elsevier
• Subjects: Amphipoda; Animal, plant and microbial ecology; Animals; Applied ecology; Bathing Beaches - statistics & numerical data; Beach erosion; Beach nourishment; Beaches; Biological and medical sciences; Bivalvia; Brachyura; Conservation of Natural Resources - methods; Conservation, protection and management of environment and wildlife; Decapoda; Degradation; Density; Disturbances; Donax; Ecological recovery; Ecosystem; Emerita talpoida; Environmental degradation: ecosystems survey and restoration; Environmental Restoration and Remediation - methods; Fundamental and applied biological sciences. Psychology; Geologic Sediments - chemistry; Impact assessment; Invertebrates; Invertebrates - growth & development; Marine; Monitoring; Particle Size; Press response; Presses; Sediments; Beach nourishment; Ecological recovery; Press response; Impact assessment; Beach erosion; Littoral zone; Fauna; Many-yeared experiment; Sediments; Amphipoda; Infauna; Crustacea; Degradation; Persistence; Bivalvia; Animal community; Arthropoda; Habitat; Erosion control; Invertebrata; Mollusca
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2014.04.046

Beach nourishment is increasingly used to protect public beach amenity and coastal property from erosion and storm damage. Where beach nourishment uses fill sediments that differ in sedimentology from native beach sands, press disturbances to sandy beach invertebrates and their ecosystem services can occur. How long impacts persist is, however, unclear because monitoring after nourishment typically only extends for several months. Here, monitoring was extended for 3–4years following each of two spatially separated, replicate nourishment projects using unnaturally coarse sediments. Following both fill events, the contribution to beach sediments of gravel-sized particles and shell fragments was enhanced, and although diminishing through time, remained elevated as compared to control sites at the end of 3–4years of monitoring, including in the low intertidal and swash zones, where benthic macroinvertebrates concentrate. Consequently, two infaunal invertebrates, haustoriid amphipods and Donax spp., exhibited suppressed densities over the entire post-nourishment period of 3–4years. Emerita talpoida, by contrast, exhibited lower densities on nourished than control beaches only in the early summer of the first and second years and polychaetes exhibited little response to nourishment. The overall impact to invertebrates of nourishment was matched by multi-year reductions in abundances of their predators. Ghost crab abundances were suppressed on nourished beaches with impacts disappearing only by the fourth summer. Counts of foraging shorebirds were depressed for 4years after the first project and 2years after the second project. Our results challenge the view that beach nourishment is environmentally benign by demonstrating that application of unnaturally coarse and shelly sediments can serve as a press disturbance to degrade the beach habitat and its trophic services to shorebirds for 2–4years. Recognizing that recovery following nourishment can be slow, studies that monitor impacts for only several months are inadequate. •We monitored recovery of sandy beach fauna for 3–4years following nourishment.•The application of unnaturally coarse sediments served as a press disturbance.•Abundances of haustoriid amphipods and Donax were suppressed for the entire study.•Impacts to invertebrates were matched by reduced abundances of their predators.•Hence, mismatch of fill and native beach sediments can produce lasting impacts.