ALBERT

Description: Highlights: • First study to compare microplastic effects over a wide biogeographical range • Comparison between natural inorganic microparticles and plastic microparticles • Significant effects on byssus production, respiration and clearance rates, but small effect sizes • No ecologically relevant difference between impact of plastic and natural inorganic microparticles on Mytilidae Abstract: Microplastics are ubiquitous in the marine environment and studies on their effects on benthic filter feeders at least partly revealed a negative influence. However, it is still unclear whether the effects of microplastics differ from those of natural suspended microparticles, which constitute a common stressor in many coastal environments. We present a series of experiments that compared the effects of six-week exposures of marine mussels to two types of natural particles (red clay and diatom shells) to two types of plastic particles (Polymethyl Methacrylate and Polyvinyl Chloride). Mussels of the family Mytilidae from temperate regions (Japan, Chile, Tasmania) through subtropical (Israel) to tropical environments (Cabo Verde) were exposed to concentrations of 1.5 mg/L, 15 mg/L and 150 mg/L of the respective microparticles. At the end of this period, we found significant effects of suspended particles on respiration rate, byssus production and condition index of the animals. There was no significant effect on clearance rate and survival. Surprisingly, we observed only small differences between the effects of the different types of particles, which suggests that the mussels were generally equally robust towards exposure to variable concentrations of suspended solids regardless of whether they were natural or plastic. We conclude, that microplastics and suspended solids elicit similar effects on the tested response variables, and that both types of microparticles mainly cause acute responses rather than more persistent carry-over effects.

Description: Highlights: • Long-term (63–68 days) particle exposure had only minor negative effects on Semimytilus algosus. • Negative effects of microplastics were observed only at higher and less environmentally realistic concentrations. • Procedural controls with natural microparticles are essential for the interpretation of microplastic exposure studies. Laboratory exposure studies allow to investigate the impact of microplastics on marine biota, but commonly lack a procedural control, i.e. assessing the effects of natural microparticles. In two experiments with the mussel Semimytilus algosus, we compared the effects of clay vs. polyvinyl chloride (PVC) and celite vs. polymethylmethacrylate (PMMA), respectively, at concentrations of 1.5, 15 and 150 mg l(-1) After more than 60 days, no effects on respiration and clearance rates, mortality and byssus strength were observed. However, in mussels exposed to PVC the Body Condition Index was 34% lower at 150 mg l(-1) than at 1.5 mg l(-1). Furthermore, at 15 mg l(-1), mussels exposed to microplastics produced over 40% less byssus than those exposed to natural micro particles. This suggests that mussels react differently to natural microparticles and to microplastics, but only at high particle loads that exceed current environmental microplastic concentrations by orders of magnitude.

Description: This dataset comprises data obtained during a 6 week-long exposure experiment of mussels of the family Mytilidae to two types of microplastics, namely polymethyl methacrylate (PMMA) and polyvinylchloride (PVC) particles and two types of natural inorganic microparticles, namely diatoms and red clay. This data was obtained from May to September 2019 in five different bioregions, which are Tasmania, Chile, Japan, Cabo Verde and Israel. We recorded body condition index, byssus thread production in 24 hours, clearance rate of the food algae and respiration rate at the end of six weeks of exposure to the four different microparticles (with an exception of the groups exposed to PVC and red clay in Tasmania, which lasted 5 weeks). Mussels were exposed to three concentrations of each particle type, which were 1.5, 15 and 150 mg/l and one group to no particles at all as control.