To assess the potential of long-lived freshwater bivalve shells as a proxy for river environments, we examined daily and annual growth increments and analysed trace elements in the shells of Margaritifera laevis collected alive from the Shiribetsu River, located in the central western region of Hokkaido, Japan. The sum of the daily growth lines within a single annual increment corresponded to the days when the average daily water temperature was greater than 9 °C, suggesting that shell deposition occurred from spring to autumn. The growing degree days (GDD) are correlated with the maximum snow depth in winter and the average river discharge in spring. We conducted trace element microanalysis across daily and annual growth increments by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and compared the results with in situ environmental data. Sharp peaks in the barium/calcium ratio (Ba/Ca) observed during spring river discharge also suggest that the growth of Margaritifera shells is influenced by winter snow volume and meltwater. A 67-year profile of the standard growth index (SGI) estimated from twelve individual annual growth histories correlates to the annual snowfall accumulation. Distinct decadal variability is observed in the SGI and synchronized with the North Pacific Index and Pacific Decadal Oscillation. Sclerochronological approaches using Margaritifera shells could be valuable for reconstructing river and atmospheric conditions during the winter season, which is influenced by the Asian winter monsoon in the central Hokkaido region.

为了评估长寿的淡水双壳类贝壳作为河流环境的替代物的潜力，我们检查了每日和每年的生长增量，并分析了玛格丽特海藻壳中的微量元素。从位于日本北海道中部西部的Shiribetsu河中收集的活物。单个年增量内每日生长线的总和对应于平均每日水温高于9°C的日子，这表明壳层沉积发生于春季至秋季。生长度日数（GDD）与冬季最大的积雪深度和春季的平均河流量相关。我们通过激光烧蚀电感耦合等离子体质谱法（LA-ICP-MS）对每日和每年的增长增量进行了痕量元素微分析，并将结果与​​原位环境数据进行了比较。在春季河水排放期间观察到的钡/钙比（Ba / Ca）的尖峰也表明玛格丽特酵母的生长贝壳受冬季降雪量和融水的影响。根据十二个单独的年度增长历史估算的标准增长指数（SGI）的67年概况与年度降雪量相关。在SGI中观测到明显的年代际变化，并与北太平洋指数和太平洋年代际振荡同步。在北海道中部地区受亚洲冬季风影响的冬季，使用玛格丽塔壳的年代学方法对于重建冬季的河流和大气条件可能是有价值的。