Selenium (Se) bioaccumulation and toxicity in aquatic vertebrates have been thoroughly investigated. Limited information is available on Se bioaccumulation at the base of aquatic food webs. In this study, we evaluated Se bioaccumulation in two benthic macroinvertebrates (BMI), Hyalella azteca and Chironomus dilutus raised in the laboratory and caged in-situ to a Canadian boreal lake e (i.e., McClean Lake) that receives continuous low-level inputs of Se (< 1 μg/L) from a uranium mill. Additional Se bioaccumulation assays were conducted in the laboratory with these BMI to (i) confirm field results, (ii) compare Se bioaccumulation in lab-read and native H. azteca populations and (iii) identify the major Se exposure pathway (surface water, top 1 cm and top 2–3 cm sediment layers) leading to Se bioaccumulation in H. azteca. Field and laboratory studies indicated overall comparable Se bioaccumulation and trophic transfer factors (TTFs) in co-exposed H. azteca (whole-body Se 0.9–3.1 µg/g d.w; TTFs 0.6–6.3) and C. dilutus (whole-body Se at 0.7–3.2 µg Se/g d.w.; TTFs 0.7–3.4). Native and lab-reared H. azteca populations exposed to sediment and periphyton from McClean Lake exhibited similar Se uptake and bioaccumulation (NLR, p = 0.003; 4.1 ± 0.8 µg Se/g d.w), demonstrating that lab-reared organisms are good surrogates to assess on-site Se bioaccumulation potential. The greater Se concentrations in H. azteca exposed to the top 1–3 cm sediment layer relative to waterborne exposure, corroborates the importance of the sediment-detrital pathway leading to greater Se bioaccumulation potential to higher trophic levels via BMI.

硒 (Se) 在水生脊椎动物中的生物累积和毒性已得到彻底研究。关于水生食物网底部硒生物累积的信息有限。在本研究中，我们评估了两种底栖大型无脊椎动物 (BMI)（Hyalella azteca和Chironomus dilutus ）中 Se 的生物富集情况，这些动物在实验室中饲养，并就地关在加拿大北方湖泊 e（即麦克莱恩湖）中，该湖接受持续的低水平输入来自铀厂的 Se (< 1 μg/L)。在实验室中利用这些 BMI 进行了额外的 Se 生物累积测定，以 (i) 确认现场结果，(ii) 比较实验室读取的和本地H. azteca种群中的 Se 生物累积情况，以及 (iii) 确定主要的 Se 暴露途径（地表水、顶部 1 厘米和顶部 2-3 厘米沉积层）导致 Se 在H. azteca中生物富集。现场和实验室研究表明，共同暴露的H. azteca（全身 Se 0.9–3.1 µg/g dw；TTF 0.6–6.3）和 C. dilutus（全身 Se ）的 Se 生物累积和营养转移因子 (TTF) 总体相当0.7–3.2 µg Se/g dw；TTF 0.7–3.4）。暴露于麦克莱恩湖沉积物和附生生物的本地和实验室饲养的H. azteca种群表现出相似的 Se 吸收和生物积累（NLR，p  = 0.003；4.1 ± 0.8 µg Se/g dw），表明实验室饲养的生物体是良好的替代品评估现场硒生物富集潜力。相对于水性暴露，暴露于顶部 1-3 cm 沉积物层的H. azteca中的 Se 浓度更高，证实了沉积物 - 碎屑途径的重要性，导致通过 BMI 实现更大的 Se 生物富集潜力，达到更高的营养水平。