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

Georg Martin,Greta Reisalu,Tiina Paalme,Kaire Torn

doi:10.3389/fmars.2021.774908

Georg Martin, Greta Reisalu + Show 2 more

Open Access

https://doi.org/10.3389/fmars.2021.774908

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Abstract

Coastal regions are biologically active areas with significant ecological and socioeconomic values. These regions are increasingly being affected by marine litter. The impact of macro-sized marine litter on biomass and net primary production of hard and soft bottom communities was investigated by using a manipulative field experiment. Plastic bags were used to mimic the disturbance caused by litter to benthic vegetation and fauna. The experiment was carried out on a soft substrate community dominated by sago pondweed Stuckenia pectinata (L.) Boerner and bladder wrack Fucus vesiculosus L. as a foundation species of a hard substrate. A rapid negative impact of the plastic bag cover on vegetation biomass of soft-bottom community was detected, while the impact on the biomass of hard bottom vegetation was non-significant. Plastic bag cover substantially reduced the net production rates of hard substrate species Fucus and the biomass of associated zoobenthos. The difference in net production rates of Stuckenia with and without plastic cover was negligible.

Highlights

Pollution of the oceans in the world by anthropogenic litter has become a serious global environmental concern
The most significant differences in the net production rates measured beneath the plastic cover in relation to the control were detected in October (Tukey’s post hoc test, p < 0.05) (Figure 4)
At the commencement of the experiment, the plastic covering reduced photosynthetically active radiation (PAR) by 12%, after a one month period PAR decreased 55%, after 2 months 75%, after 3 months 79%, and by 95% compared with the simultaneous PAR measurements without cover (Figure 2)

Summary

Introduction

Pollution of the oceans in the world by anthropogenic litter has become a serious global environmental concern. Plastic constitutes the major component of litter found in the marine environment with most of that comprised of single-use plastic such as bags and bottles (Castro-Jiménez et al, 2019; Rothäusler et al, 2019). These plastic materials are known to decompose slowly or not at all (Barboza et al, 2019; Napper and Thompson, 2019). Up to 70% of all floating plastic objects are believed to eventually settle onto the seafloor (Green et al, 2015; Weber et al, 2018)

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