School of Biological and Behavioural Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
School of Biological and Behavioural Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
Environ Pollut. 2024 Oct 15;359:124540. doi: 10.1016/j.envpol.2024.124540. Epub 2024 Jul 14.
Microplastic pollution poses a global threat to freshwater ecosystems, with laboratory experiments indicating potential toxic impacts through chemical toxicity, physical abrasion, and false satiation. Bioplastics have emerged as a potential greener alternative to traditional oil-based plastics. Yet, their environmental effects remain unclear, particularly at scales relevant to the natural environment. Additionally, the interactive impacts of microplastics with other environmental stressors, such as nutrient enrichment, are poorly understood and rarely studied. Under natural conditions organisms might be able to mitigate the toxic effects of microplastics by shifting their diet, but this ability may be compromised by other stressors. This study combines an outdoor mesocosm experiment and stable isotope analysis to determine changes in the trophic niches of three freshwater invertebrate species exposed to conventional (HDPE) and bio-based biodegradable (PLA) microplastics at two concentrations, both independently and combined with nutrient enrichment. Exposure to microplastics altered the isotopic niches of two of the invertebrate species, with nutrient enrichment mediating this effect. Moreover, the effects of microplastics were consistent regardless of their type or concentration. Under enriched conditions, two of the species exposed to microplastics shifted to a specialised diet compared with controls, whereas little difference was observed between the isotopic niches of those exposed to microplastic and controls under ambient nutrient conditions. Additionally, PLA was estimated to support 24 % of the diet of one species, highlighting the potential assimilation of bioplastics by biota and possible implications. Overall, these findings suggest that the toxic effects of microplastics suggested from laboratory studies might not manifest under real-world conditions. However, this study does demonstrate that subtle sublethal effects occur even at environmentally realistic microplastic concentrations. The crucial role of nutrient enrichment in mediating microplastic effects underscores the importance of considering microplastic pollution in the context of other environmental stressors.
微塑料污染对淡水生态系统构成全球性威胁，实验室实验表明其通过化学毒性、物理磨损和虚假饱腹感而产生潜在的毒性影响。生物塑料作为传统石油基塑料的一种潜在绿色替代品而出现。然而，其环境影响仍不清楚，特别是在与自然环境相关的规模上。此外，微塑料与其他环境胁迫因素（如营养富集）的相互影响知之甚少，很少研究。在自然条件下，生物体可能能够通过改变其饮食来减轻微塑料的毒性影响，但这种能力可能会因其他胁迫因素而受到损害。本研究结合户外中观实验和稳定同位素分析，以确定在两种浓度下，三种淡水无脊椎动物物种暴露于常规（高密度聚乙烯）和生物基可生物降解（聚乳酸）微塑料时，其营养生态位的变化，这两种微塑料都独立于营养富集，并且与营养富集相结合。暴露于微塑料改变了两种无脊椎动物的同位素生态位，而营养富集介导了这种效应。此外，无论微塑料的类型或浓度如何，其影响都是一致的。在富营养化条件下，与对照组相比，两种暴露于微塑料的物种的饮食变得更加专门化，而在环境营养条件下，暴露于微塑料和对照组之间的同位素生态位差异很小。此外，估计 PLA 支撑了一个物种的 24%的饮食，这突出了生物群可能同化生物塑料的潜力和可能的影响。总的来说，这些发现表明，实验室研究中提出的微塑料的毒性影响可能不会在现实世界条件下表现出来。然而，本研究确实表明，即使在环境现实的微塑料浓度下，也会发生微妙的亚致死效应。营养富集在介导微塑料效应中的关键作用突出表明，在考虑其他环境胁迫因素的背景下，需要考虑微塑料污染。
