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有化学自养共生体的动物理论上应该能够或多或少地连续产生配子，而不需要表面衍生的碎屑。冷渗期的混合营养型贻贝介于这两种情况之间。它们可以在只使用甲烷或硫化物作为能源的情况下生长和生存，但也能够以海底边界层中的碎屑颗粒或浮游生物为食。现有证据表明，对浮游细菌进行补充过滤可能是必要的，以向贻贝提供足够的氮。生活在路易斯安那州斜坡甲烷渗漏处的冷渗贻贝Bathymonolus Chilressi表现出周期性的繁殖，而不是连续的繁殖，这种模式没有被普遍接受的范式预测到，即食物限制控制深海的繁殖时机。因此，混合营养贻贝提供了一个独特的机会来研究碎屑输入在深海配子发生时机控制中的作用。脂类生物标记物和化合物特定的稳定同位素将被用来确定来自表面来源的碎屑的能量是否在幼虫的性腺和体细胞组织之间进行了差异分配。在深海巨型动物中，季节性繁殖者几乎总是产生摄食幼体，这表明表层生产和幼体成功之间可能存在机械或进化联系。克里斯普的规则，即预测有浮游性营养幼虫的动物将选择繁殖时间，以确保幼虫获得最佳营养，就是这样一个可能的联系。在这项研究中，将通过在不同深度收集的天然水中饲养幼虫来检验克里斯普定律。

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.