Wildfires can impact both freshwater and marine ecosystems through post-fire runoff, but its effects on bivalves, particularly those living in marine habitats, remain largely overlooked. While evidence exists that wildfire ash can alter the fatty acid (FA) and sugar profiles of aquatic biota, its influence on the biochemical profiles of bivalves have not been addressed to date. This study aimed to assess the effects of ash exposure on the FA and sugar profiles of two bivalve species used for human consumption: a freshwater clam (Corbicula fluminea) and a marine bivalve (Cerastoderma edule), additionally evaluating potential effects on their nutritional value. Both species were exposed to environmentally relevant concentrations of aqueous extracts of Eucalypt ash (AEAs) for 96 hours. Results showed species-specific responses to ash extracts exposure, with more pronounced effects on C. edule. This species exhibited a trend for reduced FA content, statistically significant for C17:0 but also evident for unsaturated FAs, which is relevant for human health as they represent a decrease in the nutritional value. Conversely, an increase in the sugar content of this species was observed with increasing AEA concentrations, despite only statistically significant for galactose and xylose. In contrast, the clams exhibited only minor effects, showing a trend for increased FA and decreased sugar contents, but only significant for the monounsaturated FA content. This study suggests a higher sensitivity of marine bivalves to wildfire ash compared to their freshwater counterparts. Moreover, it highlights, for the first time, the potential of post-fire runoff to alter the biochemical profiles of bivalve species, raising concerns about broader impacts on aquatic trophic webs and human health, an issue that becomes particularly relevant given the forecasted increase in wildfire’s frequency and extension due to global warming.

中文翻译：

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野火灰烬对双壳类脂肪酸和糖分的影响——淡水和海洋物种的比较研究


野火可以通过火灾后的径流影响淡水和海洋生态系统，但它对双壳类的影响，特别是那些生活在海洋栖息地的双壳类动物，在很大程度上仍然被忽视了。虽然有证据表明野火灰烬可以改变水生生物群的脂肪酸 （FA） 和糖分，但迄今为止尚未解决其对双壳类生化特征的影响。本研究旨在评估灰烬暴露对两种供人类食用的双壳类物种的 FA 和糖分的影响：淡水蛤 （Corbicula fluminea） 和海洋双壳类 （Cerastoderma edule），此外还评估了对其营养价值的潜在影响。两个物种都暴露于环境相关浓度的桉树灰 （AEA） 水提取物中 96 小时。结果显示，对灰烬提取物暴露的物种特异性反应，对 C. edule 的影响更为明显。该物种表现出 FA 含量降低的趋势，对于 C17：0 具有统计学意义，但对于不饱和 FA 也很明显，这与人类健康有关，因为它们代表营养价值的降低。相反，随着 AEA 浓度的增加，观察到该物种的糖含量增加，尽管半乳糖和木糖仅具有统计学意义。相比之下，蛤蜊仅表现出轻微的影响，表现出 FA 增加和糖含量降低的趋势，但对单不饱和 FA 含量仅显着。这项研究表明，与淡水双壳类相比，海洋双壳类对野火灰烬的敏感性更高。 此外，它首次强调了火灾后径流可能改变双壳类物种的生化特征，引发了人们对水生营养网和人类健康更广泛影响的担忧，鉴于全球变暖导致野火频率和扩展的预测增加，这个问题变得尤为重要。