Concern over the effects of microplastics on estuarine ecosystems and public health has prompted many restoration practitioners to switch from plastic materials to more “environmentally friendly” substrates. These natural (BESE biopolymer, cement-jute rings) and non-plastic (basalt fiber) materials shouldn’t contain any harmful substances; however, their chemical composition is unknown. Natural materials may degrade faster in subtropical environments and release nutrients into surrounding waters, which is concerning for eutrophic areas. Basalt fiber bags haven’t been evaluated for biogeochemical impacts within estuaries. To address these knowledge gaps, field and laboratory experiments were complemented by a chemical evaluation of these three non-plastic materials to gain an understanding of their potential impacts on soil and water biogeochemistry. In the field, material effects on sediment properties 6 months post-restoration and mass loss of materials deployed in litterbags at sites in Texas and Florida were quantified. Material composition and nutrient release under laboratory conditions were also quantified. For basalt only, impacts on microbial respiration, biomass, and enzyme activity was also assessed. Field studies showed no short-term (6-months) impact of materials on sediment properties, but mass loss of BESE-mesh and basalt fiber. Nutrient leaching studies showed most DIN release by cement-jute and greater release of DOC by basalt fiber than other materials. Microbial study results suggest basalt fiber could stimulate microbial activity and release of nutrients from sediment. These results support that these alternative materials aren’t inert and demonstrate the need to consider all possible effects on ecosystem health and water quality before choosing a restoration material.
Cadie Barnes
Dr. Lisa Chambers, Advisor
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