Abstract

Freshwater mussels are both critically important in their ecosystems and rapidly declining around the world. Damming is a key reason for this decline in many locations because it affects the flow and turbidity of river systems, leading to numerous detrimental effects on benthic communities. Although the ecological effects of impoundment have been well studied on timescales ranging from years to decades, the ecological effects of impoundment on longer (50–100 years) timescales are less well understood, with a key question being: how long after the building of dams and impoundments do we expect community structure to continue changing? In this study, we explore historical changes in the freshwater mussel assemblages in Kentucky Lake (dammed in 1944) using decades-long collections housed at Murray State University in combination with other historical records. After digitizing these collections and applying a robust rarefaction protocol to account for uneven sampling, we quantify changes in unionid assemblage structure alongside coeval water quality data collected through the Kentucky Lake Long-Term Monitoring Program. We find that subsampled richness exhibited declines after dam construction with losses among opportunistic taxa, channelization-tolerant taxa, and impoundment-intolerant taxa. We also find increases in the proportions of equilibrium taxa throughout the dataset. Overall, the assemblage composition reached an equilibrium by the year 2000 (50 years after impoundment). In concert, river water quality data show a decline in turbidity and increase in light penetration in the period 1988–2020. Although the geohistorical records treated in this study are patchy in time, we argue that they are nonetheless valuable and illustrate that freshwater ecosystems may serve as potential sites of restoration decades after anthropogenic disturbance. In turn, this emphasizes the importance of geohistorical collections to studying long-term changes in community structure and developing strategies for conservation and environmental remediation.

摘要

淡水贻贝在其生态系统中至关重要，但在世界范围内迅速减少。筑坝是许多地方水量下降的一个关键原因，因为它会影响河流系统的流量和浑浊度，从而对底栖生物群落造成许多不利影响。尽管蓄水的生态效应在几年到几十年的时间尺度上得到了很好的研究，但蓄水在更长（50-100 年）时间尺度上的生态效应却鲜为人知，一个关键问题是：大坝建成后多长时间和蓄水 我们是否期望社区结构继续发生变化？在这项研究中，我们使用默里州立大学长达数十年的收藏品并结合其他历史记录，探索肯塔基湖（1944 年筑坝）淡水贻贝组合的历史变化。在将这些集合数字化并应用强大的稀疏协议来解释不均匀采样后，我们量化了 unionid 组合结构的变化以及通过肯塔基湖长期监测计划收集的同时期水质数据。我们发现，在大坝建设后，二次抽样的丰富度有所下降，机会主义类群、渠道耐受性类群和蓄水不耐受类群之间存在损失。我们还发现整个数据集中平衡分类群的比例有所增加。总体而言，组合构成在 2000 年（蓄水后 50 年）达到平衡。在演唱会，河流水质数据显示，1988-2020 年期间浊度下降，透光度增加。尽管本研究中处理的地球历史记录在时间上是零散的，但我们认为它们仍然很有价值，并说明淡水生态系统可能在人为干扰后几十年成为潜在的恢复地点。反过来，这强调了地理历史收藏对于研究社区结构的长期变化以及制定保护和环境修复战略的重要性。我们认为它们仍然很有价值，并说明淡水生态系统可以作为人为干扰几十年后的潜在恢复地点。反过来，这强调了地理历史收藏对于研究社区结构的长期变化以及制定保护和环境修复战略的重要性。我们认为它们仍然很有价值，并说明淡水生态系统可以作为人为干扰几十年后的潜在恢复地点。反过来，这强调了地理历史收藏对于研究社区结构的长期变化以及制定保护和环境修复战略的重要性。