Abstract

Community-based oyster reef restoration historically involved deploying plastic-based restoration units. However, many practitioners now seek to eliminate plastic usage due to environmental concerns. Scientific investigation into the efficacy and environmental safety of novel, non-plastic restoration products is limited. Four non-plastic shell bag materials (three biopolymers, one basalt fiber) were tested in field and laboratory studies, using plastic controls. In Mosquito Lagoon, FL, USA, a subtropical estuary, units at four restored reefs were monitored quarterly for one year. A 12-month laboratory study examined these same materials and their potential to shed microparticles. In the field, all biopolymers exhibited low persistence (≤17% remaining after 12 months). Basalt had high persistence (96%), but developed large rips by the end of the study. Oyster recruitment was negatively associated with damage to shell bags due to substrate loss. In the laboratory, basalt fiber shed high numbers of thin, rod-like microparticles (1987.4 microparticles/year ± 256.4 SE). Other materials shed <5 microparticles/year on average. Low durability of experimental materials emphasizes the need for more resilient restoration products that can withstand conditions in subtropical marine ecosystems. It is unknown if basalt microparticles impact marine environments, but further study is imperative given the high volume that was shed.

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