We reported the accumulation of conservative-type elements (lithium (Li), magnesium (Mg), molybdenum (Mo), antimony (Sb), cesium (Cs), and uranium (U) in pelagic species of Sargassum brown alga (S. fluitans and S. natans). We also included individuals of benthic Sargassum species, inhabiting a reef ecosystem influenced by urban developments and tourist activities. By assuming a set of premises for a normalizing element, Li was used to calculate the bioaccumulation factor (BAF) of the bio-unlimited elements in pelagic and benthic Sargassum relative to the seawater levels. Both pelagic species displayed levels in the same order of abundance as in seawater from the central Atlantic Ocean and the Caribbean Sea (Mg> > Li ~ Mo > U > Sb > Cs), except Sb. Bio-unlimited element levels and BAFs were comparable in S. fluitans and S. natans but lower than benthic Sargassum, except for U. Temporal variations were observed in the metal contents, except Li, with higher values from July to October regarding the February–May period. Those variations were unexpected considering their conservative-type behavior in oceanic waters. Metabolic changes related to the life cycle explain variations for Mg and Mo. Anthropogenic Sb inputs, via atmospheric dust, could constitute a significant metal source to surface seawater and the pelagic Sargassum. S. fluitans and S. natans arriving at the Caribbean coasts are excellent biomonitors to study trace metals scarcely studied in oceans, such as bio-unlimited elements. Lithium met the premises to be used as a reference element to determine their bioaccumulation of metals (uptake and retention). So, estimations of BAFs by normalizing to Li constitute a useful tool for metal assessment using macroalgae as an environmental biomonitor.

我们报道了在马尾藻褐藻（S. Fluitans和S. natans )。我们还包括了居住在受城市发展和旅游活动影响的珊瑚礁生态系统中的底栖马尾藻物种的个体。通过假设一组归一化元素的前提，使用 Li 来计算生物累积因子 (BAF)中上层和底栖马尾藻中的生物无限元素相对于海水水位。两种远洋物种的丰度水平与大西洋中部和加勒比海海水中的丰度相同（Mg> > Li ~ Mo > U > Sb > Cs），但 Sb 除外。S. fluitans 和 S. natans的生物无限元素水平和 BAF 相当，但低于底栖马尾藻，除了 U。在金属含量中观察到了时间变化，除了 Li，从 7 月到 10 月的值高于 2 月-五月期。考虑到它们在海水中的保守型行为，这些变化是出乎意料的。与生命周期相关的代谢变化解释了 Mg 和 Mo 的变化。通过大气尘埃输入的人为 Sb 可能构成地表海水和中上层海洋的重要金属来源马尾藻。到达加勒比海岸的S. fluitans 和 S. natans是优秀的生物监测器，可以研究在海洋中很少研究的微量金属，例如生物无限元素。锂满足了用作参考元素的前提条件，以确定其金属的生物累积性（吸收和保留）。因此，通过标准化为 Li 来估计 BAF 构成了使用大型藻类作为环境生物监测器进行金属评估的有用工具。