Deterioration of submersed plastic used for habitat and restoration structures in Texas reservoirs: Considerations for fishery managers

ABSTRACT Currently, plastic is a commonly used material for fish habitat (i.e., do-it-yourself [DIY] and commercially sold kits) by fishery managers. The benefit of this material is that it is lightweight and easy to use compared with heavy, cumbersome natural materials (i.e., wood and rock). Unfortunately, many fishery managers are left to make their own decisions on whether plastic is a safe alternative to natural materials. There are concerns because fish habitat is intentionally left for the long term (permanently) within dynamic aquatic systems, like reservoirs. The intent of this study was to (1) identify, to polymer, which plastics have historically been used for fish habitat and restoration projects (both DIY and commercially sold products) by a single state conservation agency (circa 2015–2022) and (2) determine whether underwater degradation of plastics is observable by artificially aging certain plastics using a novel underwater accelerated-aging chamber. Multiple techniques were used to determine these answers including analytical chemistry (Fourier transform infrared spectroscopy), mechanical stress (flexural modulus), and surface morphology (scanning electron microscopy). The results determined that eight unique polymers are currently in use and that these polymers are often used in combination for a single fish habitat structure. Furthermore, we found evidence from our artificially aged samples (e.g., nylon, polyvinyl chloride, chlorinated polyvinyl chloride, and high-density polyethylene) suggesting that aging by using temperature (heat) can be observed within 1 year of underwater deployment. This article offers fishery managers insights into the limitations of plastic as a construction material for submersed structures while challenging common misconceptions and bridging information gaps.