Texas A&M Natural Resources Institute, TAMU, 578 John Kimbrough Blvd. 2260, College Station, TX, 77843, USA.
Texas A&M AgriLife Research and Extension Center at Dallas, 17360 Coit Rd., Dallas, TX, 75252, USA.
Sci Rep. 2024 Sep 5;14(1):20659. doi: 10.1038/s41598-024-71597-8.
Unionid mussels deposit growth rings (annuli) within the shell, which can be used to estimate age and growth. Thin-sectioning is a common technique for counting annuli, wherein a cross-section of a shell valve is taken and evaluated by multiple readers. Correctly identifying annuli can be challenging because ambiguous annuli can bias growth estimates. Staining with calcein, a fluorescent chemical, is a technique that has been used with marine and freshwater species to improve accuracy of growth estimates. This method chelates calcium, causing a permanent mark that fluoresces under ultraviolet light. Calcein has seen limited testing on unionid mussels so it remains unclear if this method has adverse effects on survival and growth. We evaluated calcein against 2 concentrations (125 mg L and 250 mg L) at 2 exposure times (12 and 24 h) on Cyclonaias pustulosa, a common North American unionid. Survivorship remained above 80% 6 months post-immersion. Mark quality and retention for 250 mg L were high for both 12- and 24-h immersions, although historical annuli were not highlighted. These findings corroborate studies indicating calcein immersion is generally safe and effective in juveniles and adults and suggest it may be useful in validating new growth.
淡水贻贝在贝壳内沉积生长环（年轮），可用于估计年龄和生长情况。薄片分析是一种常见的计数生长环的技术，通过对贝壳阀的横截面进行多次读取来评估。正确识别生长环具有一定挑战性，因为模糊的生长环会使生长估计产生偏差。使用钙黄绿素（一种荧光化学物质）进行染色是一种已应用于海洋和淡水物种的技术，可提高生长估计的准确性。该方法螯合钙，形成永久性标记，在紫外线下发出荧光。钙黄绿素在淡水贻贝类中的应用测试有限，因此尚不清楚这种方法是否会对存活和生长产生不利影响。我们评估了钙黄绿素在 2 种浓度（125mg/L 和 250mg/L）下、2 种暴露时间（12 小时和 24 小时）下对常见的北美淡水贻贝 Cyclonaias pustulosa 的影响。浸泡后 6 个月，存活率仍保持在 80%以上。24 小时和 12 小时浸泡后，250mg/L 浓度的标记质量和保留率均较高，尽管未突出显示历史生长环。这些发现与表明钙黄绿素浸泡在幼体和成体中通常安全且有效的研究结果相符，并表明其在验证新的生长方面可能有用。
