Shell trace elemental data (geochemical fingerprints) from larval samples collected during cruises AT42-24, AT50-04, and TN391 in the Gulf of Mexico and Northwestern Atlantic in 2020, 2021, and 2022

Larval dispersal drives metapopulation connectivity, a key metric of population resilience to disturbance. Deep-sea larval disperal remains poorly understood due to the limited applicability of nearshore approaches such as larval rearing in-situ. Here, we used laser ablation spectrometry (Jackson School of Geosciences at the University of Texas at Austin) and multivariate statistical analyses (i.e., PERMANOVA and CAP) to quantify larval shell trace elemental fingerprints for deep-sea methane seep mussels Gigantidas childressi and Bathymodiolus heckerae to infer spatiotemporal mixing of larval population pools in the Gulf of Mexico and Western Atlantic Margin. Larvae were collected during R/V Atlantis cruises AT42-24 (Spring 2020) and AT50-04 (Fall 2022), and R/V Thomas G. Thompson  cruise TN-391 (Summer 2021). We analysed variation in fingerprints of 366 larvae among depths (500-3,000m), seven seep sites, and three sampling years (spawning periods). Fingerprints differed significantly among depths across spawning periods, among sites within spawning periods, and among spawning periods themselves. Results may reflect divergence in sources of organic matter during dispersal due to shifts in dispersal trajectories or water mass environmental chemistry over time. Additionally, results indicate that larvae may mix during early dispersal (i.e., during formation of the prodissoconch I shell growth region) and become more isolated by later dispersal (i.e., formation of prodissoconch II). Overall, over timescales of only a few years, deep-sea mussel larval pools may be subtly spatiotemporally isolated, which may limit population resilience to natural and anthropogenic disturbance.

幼体扩散驱动集合种群（metapopulation）连通性，而连通性是种群应对干扰恢复力的核心衡量指标。受限于近岸研究方法（如原位幼体培育（larval rearing in-situ)）在深海环境中的适用性不足，当前学界对深海幼体扩散的认知仍较为匮乏。本研究借助激光烧蚀光谱法（laser ablation spectrometry，美国德克萨斯大学奥斯汀分校杰克逊地球科学学院）与多元统计分析方法（multivariate statistical analyses，具体包括置换多元方差分析PERMANOVA与主坐标典范分析CAP），对深海甲烷冷泉贻贝（deep-sea methane seep mussel）——吉氏巨贻贝（Gigantidas childressi）与赫氏深水贻贝（Bathymodiolus heckerae）的幼体壳体微量元素指纹特征（trace elemental fingerprints）进行定量分析，以此推断墨西哥湾与大西洋西部陆缘区域内幼体种群库的时空混合模式。

幼体样本采集自“亚特兰蒂斯号”（R/V Atlantis）考察航次AT42-24（2020年春季）、AT50-04（2022年秋季），以及“托马斯·G·汤普森号”（R/V Thomas G. Thompson）考察航次TN-391（2021年夏季）。本研究分析了366尾幼体的壳体微量元素指纹特征在不同水深（500~3000米）、7个冷泉点位以及3个采样年份（对应繁殖期）中的差异。结果显示，不同繁殖期内的水深梯度间、同一繁殖期内的不同点位间，以及不同繁殖期之间，幼体壳体微量元素指纹特征均存在显著差异。该结果或可反映：随着时间推移，扩散路径的改变或水团环境化学特征的变化，会导致幼体扩散过程中有机质来源出现分化。此外，研究结果表明，幼体在扩散早期（即原壳I期（prodissoconch I）壳体生长区域形成阶段）可能发生混合，而在扩散后期（即原壳II期（prodissoconch II）壳体生长区域形成阶段）则会逐渐趋于隔离。总体而言，仅在数年的时间尺度内，深海贻贝的幼体种群库便可能呈现出细微的时空隔离特征，这或会限制种群应对自然与人为干扰的恢复能力。