Texas A&M Natural Resources Institute, 578 John Kimbrough Blvd. 2260 TAMU, College Station, TX, 77843, USA.
Texas A&M AgriLife Research and Extension Center at Dallas, 17360 Coit Rd., Dallas, TX, 75252, USA.
Sci Rep. 2023 Mar 21;13(1):4603. doi: 10.1038/s41598-023-29460-9.
Freshwater mussels are particularly sensitive to hydrologic changes, including streamflow and temperature, resulting in global decline. The Devils River in south-central Texas harbors the endangered freshwater mussel Popenaias popeii (Unionidae; Texas hornshell). There is concern that water withdrawals from the underlying aquifer may be negatively impacting this species. To assess this risk, we evaluated upper thermal tolerances (LT05 and LT50) of larvae (glochidia) and juveniles from two sites. After being acclimated to 27 °C, glochidia were subjected to five experimental temperatures (30, 32, 34, 36, and 38 °C) and non-acclimated control (20 °C) for 12-h and 24-h while juveniles were subjected to three experimental temperatures (30, 32, and 36 °C) and non-acclimated control (20 °C) for 96-h. We overlaid tolerance estimates against in situ water temperature and discharge data to evaluate thermal exceedances. Additionally, we reviewed upper thermal tolerances of P. popeii's presumed host fish (Carpiodes carpio, Cyprinellas lutrensis, and Moxostoma congestum) and their congeners. Stream temperatures only occasionally exceeded mussel LT05/50 and fish CLMax/LTMax, likely due to the Devils River's large spring input, highlighting the importance of protecting spring flows. We provide a practical framework for assessing hydrological needs of aquatic ectotherms, including the parasite-host relationship, which can be used to optimize environmental management.
淡水贻贝对水文变化特别敏感，包括流量和温度，这导致了它们在全球范围内的减少。德克萨斯州中南部的魔鬼河（Devils River）是濒危淡水贻贝 Popenaias popeii（贻贝科；德克萨斯角贝）的栖息地。人们担心从地下含水层中抽取的水可能会对这种物种产生负面影响。为了评估这种风险，我们评估了来自两个地点的幼虫（钩介幼虫）和幼贝的上临界热耐受值（LT05 和 LT50）。在适应 27°C 后，将钩介幼虫置于五个实验温度（30、32、34、36 和 38°C）和非适应对照（20°C）下 12 小时和 24 小时，而幼贝则在三个实验温度（30、32 和 36°C）和非适应对照（20°C）下 96 小时。我们将耐受估计值与原位水温和流量数据重叠，以评估热超过的情况。此外，我们还审查了 P. popeii 假定宿主鱼（鲤鱼、泥鳅和密西西比鳄）及其近缘种的上临界热耐受值。溪流温度仅偶尔超过贻贝 LT05/50 和鱼类 CLMax/LTMax，这可能是由于魔鬼河有大量的泉水补给，这突显了保护泉水流量的重要性。我们提供了一个评估水生变温动物（包括寄生虫-宿主关系）水文需求的实用框架，可用于优化环境管理。
