Consejo de Investigaciones Científicas y Técnicas (CONICET), Argentina; Departamento de Ciencias Básicas, Universidad Nacional de Luján, Argentina.
Inst. Ecologia Aquàtica and Dep. Ciències Ambientals, Universitat de Girona, Campus de Montilivi, 17071 Girona, Spain.
Sci Total Environ. 2015 Jan 15;503-504:122-32. doi: 10.1016/j.scitotenv.2014.06.094. Epub 2014 Jul 6.
Periphyton communities grown in microcosms were studied under the exposure to different arsenate (As) and phosphate (P) regimes with the aim of revealing the effect of chronic exposure to As on periphyton physiological and structural characteristics. Also, we aimed to study periphyton changes on sensitivity to As, exposed to different P and As regimes. As affected structural and functional parameters of periphyton communities starved of P, inhibiting algal growth, photosynthetic capacity, changing community composition and reducing the ability of the community to retain P. The effects of As on these parameters were only detected in P starved communities, showing that chronic exposure to As led to changes in the photosynthetic apparatus under the conditions of P-limitation, but not when P-availability was higher. This fact reveals a lower toxicity and/or a higher adaptation of the P-amended community. Intracellular As contents were higher in communities starved of P. However, As tolerance was only induced by the combination of As and P but not by As or P alone indicating that tolerance induction may be an ATP-dependent mechanism. This study reveals that chronic exposure of natural communities to environmentally realistic As concentrations will damage periphyton communities affecting key ecosystem processes, as P uptake, leading to changes in stream ecosystems, as these organisms play a key role in nutrient cycling through nutrient uptake and transfer to higher trophic levels.
以微宇宙中生长的周丛生物群落为研究对象，在不同砷酸盐（As）和磷酸盐（P）处理条件下进行暴露实验，旨在揭示长期暴露于砷对周丛生物生理和结构特征的影响。此外，我们还研究了周丛生物对不同 P 和 As 处理条件下砷敏感性的变化。P 饥饿会抑制藻类生长、光合作用能力、改变群落组成并降低群落保留 P 的能力，从而影响周丛生物群落的结构和功能参数。只有在 P 饥饿的情况下，As 才会对这些参数产生影响，这表明，在 P 限制条件下，长期暴露于 As 会导致光合作用器发生变化，但在 P 更充足的情况下不会发生这种变化。这一事实表明，P 补充的群落具有较低的毒性和/或更高的适应性。在 P 饥饿的群落中，细胞内的 As 含量更高。然而，只有 As 和 P 的组合才能诱导对 As 的耐受性，而单独的 As 或 P 则不能诱导，这表明耐受诱导可能是一种依赖于 ATP 的机制。本研究揭示了自然群落长期暴露于环境现实浓度的 As 会损害周丛生物群落，影响关键的生态系统过程，如 P 吸收，从而导致溪流生态系统的变化，因为这些生物通过吸收营养物质并将其转移到更高的营养水平，在营养循环中起着关键作用。
