A common contaminant shifts impacts of climate change on a plant-microbe mutualism: effects of temperature, CO₂and leachate from tire wear particles

Abstract

1Anthropogenic stressors, such as climate change or chemical pollution, affect indi-2 vidual species and alter species interactions. Moreover, species interactions can modify 3 effects of anthropogenic stressors on interacting species -a process which may vary 4 amongst stressors or stressor combinations. Most ecotoxicological work focuses on 5 single stressors on single species. Here, we test hypotheses about multiple stressors 6 (climate change and tire wear particles) and interacting species, and whether species 7 interactions modify responses. We use duckweed and its microbiome to model responses 8 of plant-microbe interactions. Climate change is occurring globally, and with increasing 9 urbanization, tire wear particles increasingly contaminate road runoff. Their leachate is 10 associated with zinc, PAHs, plastic additives, and other toxic compounds. We crossed 11 perpendicular gradients of temperature and CO 2 in a well plate with factorial manip-12 ulation of leachate from tire wear particles and presence of duckweed microbiomes. 13 We measured duckweed and microbial growth, duckweed greenness, and plant-microbe 14 growth correlations. We found that tire leachate and warmer temperatures enhanced 15 duckweed and microbial growth, but microbes diminished positive responses in duck-16 weed, meaning microbiomes became costly for duckweed. These costs of microbiomes 17 were less-than-additive with warming and leachate, and might be caused by leachate-18 disrupted endocrine signaling in duckweed. We observed reduced greenness at higher 19 CO 2 without tire leachate, suggesting a relative increase in plant nutrient demand, and 20 possibly underlying positive plant-microbe growth correlations in these conditions, as 21 microbes presumably increase nutrient availability. However, with tire leachate, growth 22 correlations were never positive, and shifted negative at lower CO 2 , further suggesting 23 leachate favors mutualism disruption. In summary, while individual stressors of global 24 change can affect individual species, in ecology we know species interact; and in ecotox-25 icology, we know stressors interact. Our results demonstrate this complexity: multiple 26 stressors can affect species interactions, and species interactions can alter effects of 27 multiple stressors. 28

Toxicity of nanoplastics to zooplankton is influenced by temperature, salinity, and natural particulate matter

“…Advances in ecotoxicology are often limited by the number of treatments possible with experimental systems. 42,[84][85][86] Such limitations make it challenging to integrate ecological parameters into toxicity tests. Yet if we rely solely on predicted interactions of individual parameters, we may misestimate effects.…”

A Deep Dive into the Complex Chemical Mixture and Toxicity of Tire Wear Particle Leachate in Fathead Minnow

“…Tire particles were generated as described previously (Kolomijeca et al 2020; O'Brien et al 2021). A new Michelin tire (Energy‐Saving, all season, sidewall markings, 205/60R16 91 V; Amazon 2018) was used because it elicited a greater toxic response in fathead minnow embryos compared with Bridgestone (Kolomijeca et al 2020).…”

“…These pieces were finally ground using a high-powered food processor and liquid nitrogen. Tire particle sizes ranged between 1.7 µm and 1.7 mm, with surface areas between 0.002 μm 2 and 0.9 mm 2 (Supplemental Data, Figure S1; O'Brien et al 2021). Leachate samples were prepared by incubating 10 g/L of tire particles without agitation in 750-mL amber capped glass bottles of control laboratory water (Burlington [ON, Canada] city water that was carbon-filtered, ultraviolet (UV) light-sterilized in the laboratory, and sourced from Lake Ontario [ON, Canada]) in an environmental chamber at 34 °C.…”

Nanoplastic State and Fate in Aquatic Environments: Multiscale Modeling

“…Fragmented plastic litter in the aquatic environment is a growing global concern , The amount of plastic litter and expected fragmentation (e.g., via surface erosion due to mechanical, biological, or UV exposure) − far exceeds our capacity for cleanup, yet we still have a poor understanding of the hazards of fragmented particles. Establishing the full potential for harm starts with detailed knowledge of fate .…”

“…Establishing the full potential for harm starts with detailed knowledge of fate . Plastic particles vary on a number of axes that influence fate and toxicity, ,,− with fragments in the nanosized dimensions − expected to be both widely abundant in both marine and freshwater ecosystems, , and most harmful, ,, yet also the least understood.…”