High-resolution proxy records are needed to evaluate models simulating past, present and future climatic conditions. Before such records can be reliably employed, calibration studies have to be conducted to assess the confidence intervals of the proxies. Here, we use shells of the fast growing Pacific oyster Magallana gigas from the Central Wadden Sea, North Sea, a temperate barrier island-backbarrier tidal flat-salt marsh system with large seasonal changes of water mass-properties, for the calibration of geochemical proxies. M. gigas represents a non-native invasive species that rapidly develops oyster reefs. Calcite shells of two specimens from the intertidal and subtidal zones were sampled in high resolution yielding sub-monthly data sets. The time period represented in the shell, based on δ¹⁸O age modeling, was estimated at 8–10 years and the growth of the shells was restricted from (late) spring to (early) autumn of each year. Mg/Ca, Mn/Ca and Sr/Ca ratios of the intertidal and subtidal specimens show similar seasonal patterns. Mg/Ca and Sr/Ca ratios are investigated as high-resolution sea surface temperature (SST) proxies. Important ontogenetic effects (i.e., increasing time-averaging with increasing age) as well as inter-specimen variability are discussed as limiting factors for the proxy development. Intertidal Mg/Ca ratios show only a significant correlation to the high-resolution SST record of the Central Wadden Sea when the early ontogenetic stage is considered. Sr/Ca ratios were comparable in terms of absolute values and amplitudes to those of M. gigas in the Northern Wadden Sea, but amplitudes were decreasing with increasing age. These findings seriously hamper the application of Mg/Ca and Sr/Ca for reliable palaeotemperature reconstructions regardless of ontogenetic stage. The Mn/Ca ratios were investigated as proxy for Mn cycling in tidal basins, where it is interrelated with seasonal changes in primary production. In addition to the generally observed seasonal variability of the Mn/Ca oyster records, the subtidal Mn/Ca is significantly elevated compared to intertidal Mn/Ca. The subtidal Mn/Ca offset likely reflects differences in Mn cycling in tidal settings and could, therefore, serve in the palaeorecord as indicator to differentiate inter- and subtidal habitats in the same embedding sedimentary facies. This habitat effect has to be considered as an important factor besides environmental change when interpreting the high-resolution proxy record of fossil oysters.

需要高分辨率的代理记录来评估模拟过去、现在和未来气候条件的模型。在可以可靠地使用此类记录之前，必须进行校准研究以评估代理的置信区间。在这里，我们使用来自北海中央瓦登海的快速生长的太平洋牡蛎Magallana gigas 的贝壳，这是一个温带屏障岛 - 背障潮滩盐沼系统，水团特性季节性变化很大，用于校准地球化学代理。M. gigas代表一种非本地入侵物种，正在迅速发展牡蛎礁。来自潮间带和潮下带的两个标本的方解石壳以高分辨率采样，产生亚月数据集。外壳中表示的时间段，基于 δ ¹⁸O 年龄建模，估计为 8-10 年，并且贝壳的生长从每年的（晚）春到（早）秋受到限制。潮间带和潮下带样本的 Mg/Ca、Mn/Ca 和 Sr/Ca 比率显示出类似的季节性模式。Mg / Ca 和 Sr / Ca 比率被研究为高分辨率海面温度 (SST) 代理。重要的个体遗传效应（即随着年龄的增加而增加时间平均）以及样本间变异性被讨论为代理开发的限制因素。当考虑早期个体发育阶段时，潮间带 Mg / Ca 比率仅显示与中央瓦登海的高分辨率 SST 记录显着相关。Sr / Ca 比率在绝对值和振幅方面与M. gigas 的比率相当在北瓦登海，但振幅随着年龄的增加而下降。这些发现严重阻碍了 Mg/Ca 和 Sr/Ca 在可靠的古温度重建中的应用，而不管个体发育阶段。Mn / Ca 比率被研究作为潮汐盆地中锰循环的代表，它与初级生产的季节性变化相互关联。除了普遍观察到的 Mn / Ca 牡蛎记录的季节性变化外，与潮间带 Mn / Ca 相比，潮下带 Mn / Ca 显着升高。潮下锰/钙偏移可能反映了潮汐环境中锰循环的差异，因此可以在古记录中作为区分同一嵌入沉积相中的潮间带和潮下带栖息地的指标。