Department of Zoology, David Attenborough Building, University of Cambridge, Cambridge, UK.
Department of Archaeology, University of Cambridge, Cambridge, UK.
Glob Chang Biol. 2024 Oct;30(10):e17532. doi: 10.1111/gcb.17532.
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 (δO and δC) 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. δC 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. δO and δC 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.
保存完好的生物群落可以提供有关历史生态系统和先前人为改变之前的环境条件的基本数据。淡水贻贝壳保存得特别好，在考古发掘中常见的壳组合可以提供有关过去生态系统的信息。我们研究了英格兰东部古铜器时代晚期 Must Farm 遗址（公元前 850 年）相关古河道淤泥中 Unio pictorum 贻贝壳的组合，该遗址位于现代 Nene 河的一条古老支流上。我们将来自两个沉积层（大致为公元前 1300 年至 700 年）的考古贻贝壳与现代 Nene 上两个类似地点采集的活贻贝个体进行了比较。比较了四个种群之间的大小和生长率、年际生长变异性和稳定同位素（δO 和 δC）组成。四个种群的大小和 von Bertalanffy 生长参数 L 均有所不同。两个现代种群的平均长度和 L 较高（平均长度分别为 77.3 ± 0.8 和 73.8 ± 1.1mm，L 分别为 91.8 ± 5.4 和 79.0 ± 8.1mm），而古代种群的平均长度和 L 较低（分别为 58.1 ± 1.6mm 和 68.4 ± 0.9mm；L 分别为 71.5 ± 16.9mm 和 76.8 ± 6.2mm）。现代个体的年龄校正后年际生长变化也更大。现代壳中的 δC 较低（现代壳为-11.8‰，古代壳种群为-9.03‰和-9.02‰），可能反映了水文学和养分状况的改变。除了一个采样的古代壳外，所有壳的 δO 和 δC 均呈正相关，但现代壳没有。这些结果反映了当地环境条件的变化，特别是从浅而缓慢流动的支流到更深、运河化、流速更快的河流的转变，以及人为养分富集的影响。研究结果表明，在研究人为生态系统改变和避免保护规划中转移基线综合征时，长期数据的重要性。
