Plastics and sedimentation foster the spread of a non-native macroalga in seagrass meadows

A Manipulative Field Experiment to Evaluate the Impact of Discarded Plastic Bags on Shallow Vegetated Benthic Communities

“…Studies utilizing mesocosm experiments have demonstrated that plastic bags buried in marine sediment can affect the growth of marine plants. For example, when plastic bags were buried in sediment, Mediterranean seagrass growth was observed to decline, leading to a reduction in competitiveness with invasive algae, increasing the vulnerability of seagrass to exclusion (Menicagli et al, 2021). Additionally, the changes in the geochemical parameters (reduced porewater oxygen concentrations and pH levels) of sediment were described by Balestri et al (2017).…”

“…To date, information about the effect of macrolitter that has on shallow coastal region benthic communities and habitats remains poorly understood and probably underestimated (Green et al, 2015;Angiolillo and Fortibuoni, 2020). The few mesocosm experiments that have utilized seagrasses have shown the increase of the intraspecific and interspecific competition (Balestri et al, 2017), reduction of the cover of vegetation, as well as the vulnerability of seagrasses to sedimentation where plastic bags are buried in the sediment (Menicagli et al, 2021). Furthermore, in situ experiments have only demonstrated the effect of macrolitter on benthic fauna of soft-bottom habitats.…”

Plastic pollution of four understudied marine ecosystems: a review of mangroves, seagrass meadows, the Arctic Ocean and the deep seafloor

“…After six months, the bags retained 85% of their initial mass and influenced sediment geochemistry and plant growth in complex ways. In another mesocosm experiment, the same seagrass species was exposed to both macroplastics and sedimentation [70]. After 18 months, the macroplastics were still present in the sediments, and they could make seagrasses vulnerable to sedimentation and could reduce plant cover.…”

“…However, to the best of our knowledge, we have so far only three correlational studies [39,43,47] and one experimental study [42] for the impacts of macroplastics and one meta-analysis for the impacts of microplastics [30]. For seagrass meadows, there were only three mesocosm experiments [67,69,70] for the impacts of macroplastics and none for microplastics.…”

Early evidence of the impacts of microplastic and nanoplastic pollution on the growth and physiology of the seagrass Cymodocea nodosa

“…This seagrass is considered as a useful bioindicator organism due to its ability to concentrate pollutants and silver nanoparticles in some organs (Mylona et al, 2020a). It was also proven as a useful species for testing the effects of plastic items on seagrasses (Balestri et al, 2017;Balestri et al, 2019;Menicagli et al, 2021). Specifically, we investigated under laboratory conditions whether a short-term (12 days) exposure of plants to MP/NPs induced lethal (e.g., plant mortality) or sublethal toxic effects (e.g., reduced growth, and alterations of photosynthetic efficiency and oxidative stress).…”