Preserved biological communities can provide baseline data about the historical ecosystems and environmental conditions that preceded recent anthropogenic alteration. Freshwater mussel shells show particularly good preservation, and the shell assemblages commonly found during archaeological excavations can offer insights into past ecosystems. We studied assemblages of Unio pictorum mussel shells from palaeochannel silts associated with the Late Bronze Age site of Must Farm in eastern England (c. 850 BC), on an ancient tributary of the modern‐day River Nene. We compared archaeological shells from two sediment horizons (broadly 1300–700 BC) to live individuals collected from two analogous sites on the present‐day Nene. Size and growth rate, interannual growth variability and stable isotope (δ18O and δ13C) composition were compared between the populations. Size and the von Bertalanffy growth parameter L∞ differed among all four populations. Mean lengths and L∞ were higher in the two modern populations (mean lengths 77.3 ± SE 0.8 and 73.8 ± SE 1.1 mm, L∞ 91.8 ± 5.4 and 79.0 ± 8.1 mm) than the ancient populations (mean lengths 58.1 ± SE 1.6 mm and 68.4 ± SE 0.9 mm; L∞ 71.5 ± 16.9 and 76.8 ± 6.2 mm). Modern individuals also showed greater variation in age‐corrected year‐to‐year growth. δ13C was lower in modern shells (−11.8‰ for modern shells, −9.03‰ and −9.02‰ for ancient shell populations), potentially reflecting altered hydrological and nutrient regimes. δ18O and δ13C were positively correlated for all but one sampled ancient shell, but not modern shells. These results reflect changes in local environmental conditions, particularly the transition from a shallow, slow‐flowing tributary to a deeper, canalised river with faster flow, as well as effects of anthropogenic nutrient enrichment. The findings demonstrate the importance of long‐term data in studying anthropogenic ecosystem alteration and avoiding shifting baseline syndrome in conservation planning.

中文翻译：

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淡水贻贝 （Unio pictorum） 贝壳揭示了从公元前 1300 年到现在的水文和环境变化


保存下来的生物群落可以提供有关最近人为改变之前的历史生态系统和环境条件的基线数据。淡水贻贝壳保存得特别好，考古发掘中常见的贝壳组合可以提供对过去生态系统的见解。我们研究了与英格兰东部青铜时代晚期遗址 Must Farm （约公元前 850 年）相关的古河道淤泥中 Unio pictorum 贻贝壳的组合，位于现代 Nene 河的一条古老支流上。我们将来自两个沉积物层位（大约公元前 1300-700 年）的考古贝壳与从当今 Nene 的两个类似地点收集的活体个体进行了比较。比较了种群之间的大小和生长速率、年际生长变异性和稳定同位素 （δ18O 和 δ13C） 组成。大小和 von Bertalanffy 生长参数 L∞ 在所有四个群体中都不同。两个现代种群的平均长度和 L∞ （平均长度 77.3 ± SE 0.8 和 73.8 ± SE 1.1 mm，L∞ 91.8 ± 5.4 和 79.0 ± 8.1 mm）高于古代种群（平均长度 58.1 ± SE 1.6 mm 和 68.4 ± SE 0.9 mm;长∞ 71.5 ± 16.9 和 76.8 ± 6.2 毫米）。现代个体在年龄校正后的年际增长方面也表现出更大的变化。现代贝壳的 δ13C 较低（现代贝壳为 -11.8‰，古代贝壳种群为 -9.03‰ 和 -9.02‰），可能反映了水文和营养状况的改变。除一个采样的古代贝壳外，所有采样的古代贝壳的 δ18O 和 δ13C 均呈正相关，但现代贝壳则不呈正相关。 这些结果反映了当地环境条件的变化，特别是从浅水、缓慢流动的支流过渡到更深、水流更快的运河化河流，以及人为营养物质富集的影响。研究结果表明，长期数据在研究人为生态系统改变和避免保护规划中的基线变化综合症方面的重要性。