Implications of climate change on phytoplankton - trace metal interactions

许多微量金属是浮游植物必需的微量营养元素。然而，其中一些金属在较高浓度下也可能具有毒性作用。微量金属的生物有效性影响着海洋浮游植物的生产力、固氮作用以及海洋大部分区域的物种组成，因此在全球碳循环中起着重要作用。海洋中痕量金属的生物利用度不仅取决于其总浓度，还取决于其无机形态以及与有机配体的结合。海洋酸化和海面变暖将影响海水中痕量金属的无机形态以及有机配体络合，这将潜在地显著影响其生物有效性。几种微量金属通过膜转运蛋白相互竞争生物吸收。因此，即使是轻微的变化，其生物可利用的化学形式的浓度可以影响敏感的平衡，这些金属在自然系统中的毒性作用。这可能会对来自天然来源（例如火山灰）的痕量金属的生物学意义产生重大影响。到目前为止，我们对海洋酸化和海面变暖将如何影响自然海洋系统中微量金属的生物利用度以及这将如何影响这些系统的生产力知之甚少。为了能够理解和预测这一过程对海洋浮游植物初级生产，固氮和物种组成的影响，我们迫切需要对这一主题进行详细的调查。因此，这里提出的Emmy Noether的重点将是三个方面：1）改变海水pCO 2和温度将如何影响不同痕量金属对海洋浮游植物的拮抗和/或协同效应？2)这些气候变化因素将如何影响有机微量金属配体的生物生产和结合强度，并对微量金属的生物利用度产生影响？3)海洋酸化是否会影响海水中火山灰中氟化铝复合物的毒性？我的小组将在实验室实验以及围隔生态系统实地研究中解决这些研究问题。因此，我们将使用专门开发的方法和尽可能自然的孵育条件。

Many trace metals are essential micronutrients for manne phytoplankton. However, some of these metals can also have toxic effects at higher concentrations. Trace metal bioavailability influences marine phytoplankton productivity, nitrogen fixation, and species composition in vast regions ofthe ocean and therefore plays an outstanding role in the global carbon cycle. The bioavailability of trace metals in the ocean is not only determined by their total concentration but rather by their inorganic speciation as well as by their binding to organic ligands. Ocean acidification and sea surface warming will affect the inorganic speciation as well as the organic ligand complexation of trace metals in seawater which will potentially significantly affect their bioavailability. Several trace metals compete with each other for biological uptake via membrane transporters. Therefore, even slight changes in the concentration of their bioavailable chemical forms can affect the sensitive equilibnum of fertilizing and toxic effects of these metals in natural systems. This could have a significant effect for the biological implications of trace metals from natural sources such as e.g. volcanic ash. So far we only know very little about how ocean acidification and sea surface warming will influence the bioavailability of trace metals in natural marine systems and how this will affect the productivity of these systems. To be able to understand and predict the implications of this process for marine phytoplankton primary production, nitrogen fixation, and species composition we urgently need detailed investigations of this topic. The focus of the here proposed Emmy Noether will thereby be threefold: 1) How will changing seawater pC02 and temperature influence antagonistic and/or synergistic effects of different trace metals for marine phytoplankton? 2) How will these climate change factors affect the biological production and binding strength of organic trace metal ligands with implications for trace metal bioavailability? 3) Will ocean acidification influence the toxicity of aluminium fluoride complexes from volcanic ash in seawater? My group will address these research questions in laboratory experiments as well as in mesocosm field studies. Thereby we will use specifically developed methods and incubation conditions that are as natural as possible.