Alternative Material Selection for Oyster Restoration with an Emphasis on Living Docks
Oyster restoration efforts, including Living Shoreline and Living Dock projects, utilize aquaculture-grade plastic oyster mats to mitigate the decline of benthic communities. Aquaculture-grade plastic are known for strength, durability, and resilience to degradation in seawater. Over time, plastics break into microscopic segments commonly referred to as microplastics. Microplastics represent a major concern as marine organisms mistake the small particles for food. Plastics bioaccumulate in marine species, which impacts the marine food web and humans. In order to reduce further negative anthropogenic impacts, natural fibers and nature-inspired concrete mixtures were utilized across a series of experiments in order to determine an appropriate alternative material to replace plastic in Living Dock projects. In Phase 1, coconut coir, jute, resin-coated basalt, and uncoated basalt replaced plastic oyster mats. Preliminary results revealed coconut and burlap materials are desirable for Living Dock projects and marine organism settlement, however the basalt material lacked the strength properties conducive for this usage. For Phase 2, coconut coir, two strengths of jute, and cement-coated basalt were tested. Assessment resulted in coconut coir as the recommended natural fiber for replacement in Living Docks. Phase 3assessedthe feasibility of concrete-coated natural fiber mats as an alternative. Compression strength, flexural strength, and community settlement resulted in concrete coated coconut coir being the recommended material from Phase3.While continued research is recommended, from results across the three phases of this study, coconut coir –with or without concrete –was the most suitable replacement for plastic in the Living Dock application.