Ingestion of microplastics by nematodes depends on feeding strategy and buccal cavity size

Waldman

et al. 2020

Environ. Sci. Technol.

158

With an increasing interest in the effects of microplastic in the soil environment, there is a need to thoroughly evaluate potential adverse effects of these particles as a function of their characteristics (size, shape, and composition). In addition, extractable chemical additives from microplastic have been identified as an important toxicity pathway in the aquatic environment. However, we currently know little about effects of such additives in the soil environment. In this study on nematodes (Caenorhabditis elegans), we adopted an ecotoxicological approach to assess the potential effects of thirteen different microplastics with different characteristics and extractable additives. We found that toxic effects appear to increase in the order of low-density polyethylene (LDPE) film < polypropylene (PP) fragments < high-density polyethylene (HDPE) fragments ≈ polystyrene (PS) fragments < polyethylene terephthalate (PET) fragments ≈ polyacrylicnitrile (PAN) fibers. Acute toxicity was mainly attributed to the extractable additives: when the additives were extracted, the toxic effects of each microplastic disappeared in the acute soil toxicity test. The harmful effects of LDPE film and PAN fibers increased when the microplastics were maintained in soil for a longterm period with frequent wet-dry cycles. We here provide clear evidence that microplastic toxicity in the soil is highly related to particle characteristics and extractable additives. Our results suggest that future experiments consider extractable additives as a key explanatory variable.

Section: Effects Of Microplastics On Nematodes In Soilmentioning

confidence: 99%

Effects of Different Microplastics on Nematodes in the Soil Environment: Tracking the Extractable Additives Using an Ecotoxicological Approach

Waldman

et al. 2020

Environ. Sci. Technol.

158

“…The ingestion of microplastics by nematodes is predominantly determined by their feeding habits and can be predicted by the morphology of the buccal cavity. Fueser et al (2019) showed that feeding habit and the buccal cavity of nematodes have larger effects than other factors (such as species-specific feeding differences, exposure time, and exposure concentration) on the ingestion of microplastics and could be important for controlling the quantity of microplastic uptake.…”

Section: Discussionmentioning

confidence: 99%

Ingestion of microplastics by free-living marine nematodes, especially <i>Enoplolaimus</i> spp., in Mallipo Beach, South Korea

Kang¹,

2021

Plankton Benthos Res

Many plastics cause pollution in the marine environment, with microplastics (0.1 µm-5 mm) representing a key research focus. The number of microplastics in sediments may increase rapidly, affecting organisms inhabiting marine sediments. The aim of this study was to determine how microplastics affect nematodes in intertidal sand. We assessed: (1) intake of microplastic particles (10 µm, 5 µm, 1 µm, or 0.5 µm) by Enoplolaimus spp. over 48 h; (2) microplastic intake by nematodes depending on feeding type (selective deposit feeders, non-selective deposit feeders, epistrate feeders, or predators/omnivores) over 48 h; and (3) microplastic egestion by Enoplolaimus spp. The proportion of Enoplolaimus spp. individuals containing microplastics was significantly less in the 10-µm microplastic treatment than in the treatments where Enoplolaimus spp. were exposed to microplastic particles of smaller sizes (5 µm, 1 µm, or 0.5 µm). The ingestion rates of microplastics by predators/omnivores, non-selective deposit feeders, and selective deposit feeders increased as the size of the microplastic decreased. After transferring Enoplolaimus spp. to filtered seawater following microplastic ingestion, the proportion of Enoplolaimus spp. individuals containing the smallest size microplastic (0.5 µm) decreased by 15% of the ingested amount in 3 days. In conclusion, there was a significant difference among microplastic-size treatments, but not among feeding types or in the interaction between microplastic size and feeding type. The size of microplastics, rather than feeding type of nematodes, impacted ingestion rates. It is possible that microplastics in the sediment are ingested by nematodes living in marine benthic ecosystems.

“…62,64 Although C. elegans has been suggested as a standard soil test species, 61,65 there is only one study conducting tests in soil media, 28 and 25 studies were performed using liquid media such as K-medium and M9 buffer solution (Table S2). On the other hand, six papers report size-dependent inhibitory effects of microplastic on C. elegans, [27][28][29][30]66,67 showing a tendency toward toxic effects that can be increased by smaller sizes in ranges of 0.05 to 0.2 μm, 27 0.1 to 6.0 μm, 67 and 0.1 to 5.0 μm. 29 Lei et al 30 reported that effects of microplastics in this smaller size range might not be linear, since the intermediate-sized group (1.0 μm) had the lowest survival rate, compared to smaller and larger sizes (0.1 to 0.5 and 2.0 to 5.0 μm), and Muller et al 67 found toxicity to increase in >10 μm-size range.…”

Section: Effects Of Microplastics On Nematodes In Soil C Elegans Ismentioning

confidence: 99%

“…In our study, we used a larger size range (around 250 to μm) than previous work (0.05 to 6 μm). Since the edible size of microplastic by nematode species is ≤3.4 μm, 66,67 we avoided that the nematodes fed on microplastics and followed just the influence of the potential leachates in the number of nematodes offspring. PP microplastics had a size-dependent effect, with toxicity only apparent for its smaller size range (<250 μm).…”

Section: Effects Of Microplastics On Nematodes In Soil C Elegans Ismentioning

confidence: 99%

Effects of Different Microplastics on Nematodes in the Soil Environment: Tracking the Extractable Additives using an Ecotoxicological Approach

Waldman

Rillig

2020

Preprint

ABSTRACTWith an increasing interest in the effects of microplastic in the soil environment, there is a need to thoroughly evaluate potential adverse effects of these particles as a function of their characteristics (size, shape, and composition). In addition, extractable chemical additives from microplastic have been identified as an important toxicity pathway in the aquatic environment. However, we currently know little about effects of such additives in the soil environment. In this study on nematodes (Caenorhabditis elegans), we adopted an ecotoxicological approach to assess the potential effects of thirteen different microplastics with different characteristics and extractable additives. We found that toxic effects appear to increase in the order of low-density polyethylene (LDPE) film < polypropylene (PP) fragments < high-density polyethylene (HDPE) fragments ≈ polystyrene (PS) fragments < polyethylene terephthalate (PET) fragments ≈ polyacrylicnitrile (PAN) fibers. Acute toxicity was mainly attributed to the extractable additives: when the additives were extracted, the toxic effects of each microplastic disappeared in the acute soil toxicity test. The harmful effects of LDPE film and PAN fibers increased when the microplastics were maintained in soil for a long-term period with frequent wet-dry cycles. We here provide clear evidence that microplastic toxicity in the soil is highly related to particle characteristics and extractable additives. Our results suggest that future experiments consider extractable additives as a key explanatory variable.Abstract art/Table of contents