Data from: The role of cell replacement in benthic pelagic coupling by suspension feeders

Benthic-pelagic coupling through suspension feeders and their detrital pathways is integral to carbon transport in oceans. In food-poor ecosystems however, a novel mechanism of carbon recycling has been proposed that involves direct uptake of dissolved carbon by suspension feeders followed by shedding of cells as particulate carbon. We studied cell replacement rates in a range of cold-water sponge species to determine how universal this mechanism might be. We show that cell replacement rates of feeding epithelia in explants vary from 30 hours up to 7 days, and change during different seasons and life history stages. We also found that feeding epithelia are not replaced through direct replication but instead arise from a population of stem cells that differentiate and integrate into epithelial tissues. Our results reveal a surprising amount of complexity in the control of cell processes in sponges, with cell turnover depending on environmental conditions and using stem cells as rate-limiting mechanisms. Our results also suggest that for species in cold water with high particulate organic matter, cell turnover is not the mechanism delivering carbon flux to surrounding communities.通过悬浮摄食生物（suspension feeders）及其碎屑通路（detrital pathways）实现的底栖-浮游耦合（Benthic-pelagic coupling），是海洋碳运输过程中不可或缺的核心环节。然而在食物匮乏的生态系统中，学界已提出一种全新的碳循环机制：悬浮摄食生物直接摄取溶解态碳（dissolved carbon），随后以细胞脱落的形式将其转化为颗粒态碳（particulate carbon）。本研究针对多种冷水海绵物种开展细胞替换速率分析，以探明该机制的普适性。研究结果显示，外植体（explants）中摄食上皮（feeding epithelia）的细胞替换速率介于30小时至7天之间，并随季节与生活史阶段发生变化。此外我们还发现，摄食上皮并非通过直接增殖完成替换，而是由一群干细胞（stem cells）分化并整合至上皮组织中产生的。本研究结果揭示了海绵细胞过程调控机制中远超预期的复杂性：细胞周转（cell turnover）依赖于环境条件，并以干细胞作为限速机制（rate-limiting mechanisms）。研究结果同时表明，对于栖息于颗粒有机物（particulate organic matter）含量较高的冷水环境中的物种而言，细胞周转并非向周边群落输送碳通量（carbon flux）的机制。