Collaborative Research: Energy Sources for Reproduction and Development in a Cold-Seep Mixotrophic Mussel

异养深海动物需要向下流动的物质才能生存和繁殖，而在热液喷口或冷泉处具有化能自养共生体的动物理论上应该能够或多或少连续地产生配子，而不需要表面产生的碎屑。在冷泉混合营养贻贝是这两种情况之间的中间。它们可以只利用甲烷或硫化物作为能源来生长和生存，但也能够滤食底栖边界层的碎屑颗粒或浮游生物。现有证据表明，补充过滤浮游细菌可能是必要的，以提供足够的氮的贻贝。生活在路易斯安那州斜坡甲烷渗漏处的冷渗漏贻贝Bathymodiolus childressi表现出周期性而不是连续性的繁殖，这种模式不是由普遍接受的范式预测的，即食物限制控制深海的繁殖时间。因此，混合营养贻贝提供了一个独特的机会，调查在深海配子发生时间的控制碎屑输入的作用。脂质生物标志物和化合物特异性稳定同位素将用于确定来自表面衍生碎屑的能量是否在B的性腺和体细胞组织之间差异分配。孩子们在深海巨型动物群中，季节性繁殖者几乎总是产生喂养的幼虫，这表明在表面生产和幼虫成功之间可能存在机械或进化联系。克里斯普法则（Crisp's rule）是一种可能的联系，它预测了有营养不良幼虫的动物会选择繁殖的时间，以确保幼虫获得最佳营养。本研究将通过饲养B的幼虫来检验克里斯普法则。childressi在自然水中收集在不同的深度。

Heterotrophic deep-sea animals require a downward flux of material in order to survive and reproduce, whereas animals with chemoautotrophic symbionts at hydrothermal vents or cold seeps should theoretically be capable of producing gametes more-or-less continuously without the benefit of surface-derived detritus. Mixotrophic mussels at cold seeps are intermediate between these two situations. They can grow and survive using only methane or sulfide as an energy source, but are also capable of filter-feeding on detrital particles or plankton in the benthic boundary layer. Available evidence suggests that supplemental filtration on bacterioplankton may be necessary to provide sufficient nitrogen to the mussels. The cold-seep mussel Bathymodiolus childressi, which lives at methane seeps on the Louisiana slope, demonstrates periodic rather than continuous reproduction, a pattern not predicted by the commonly accepted paradigm that food limitation controls reproductive timing in the deep sea. Thus, mixotrophic mussels present a unique opportunity to investigate the role of detrital input in the control of gametogenic timing in the deep sea. Lipid biomarkers and compound specific stable isotopes will be used to determine if energy from surfacederived detritus is differentially partitioned between the gonads and somatic tissues of B. childressi. In the deep-sea megafauna, seasonal breeders virtually always produce feeding larvae, suggesting a possible mechanistic or evolutionary link between surface production and larval success. Crisp's rule, the prediction that animals with planktotrophic larvae will time their breeding to assure optimal nutrition for the larvae, is one such possible link. Crisp's Rule will be examined in this study by rearing the larvae of B. childressi in natural water collected at various depths.