Abstract Identifying the lacustrine haptophyte species that produce long-chain alkenones (LCAs) is essential prior to down-core temperature reconstructions. Here, we investigated the identity of LCA-producing species from Lake Toyoni, Japan using 18S ribosomal DNA (rDNA) and organic geochemical analyses. The rDNA analyses identified eighteen operational taxonomic units (OTUs) of which only one fell within the haptophyte phylotype. This haptophyte belongs to the Group I phylotype, as supported by the LCA distribution found in surface and down-core sediments, and is closely related to a haptophyte found in Lake BrayaSo (Greenland). The inferred temperature using the Greenland calibration is very close to the Lake Toyoni surface temperature recorded during the spring/early summer season, when the LCA-producing haptophyte is likely to bloom. We therefore suggest that the temperature calibration from the Lake BrayaSo, Greenland is a suitable calibration for down-core temperature reconstructions at Lake Toyoni.

中文翻译：

---

日本淡水湖中长链烯酮生产者的基因组鉴定：对温度重建的影响

摘要 确定产生长链烯酮 (LCA) 的湖相触须植物物种在下核温度重建之前至关重要。在这里，我们使用 18S 核糖体 DNA (rDNA) 和有机地球化学分析研究了日本丰尼湖产 LCA 物种的身份。rDNA 分析确定了 18 个操作分类单元 (OTU)，其中只有一个属于触须植物系统发育型。这种触生植物属于 I 组系统发育型，这得到了在地表和下芯沉积物中发现的 LCA 分布的支持，并且与在 BrayaSo 湖（格陵兰）中发现的触生植物密切相关。使用格陵兰校准推断出的温度非常接近春季/初夏期间记录的 Toyoni 湖表面温度，此时产生 LCA 的触生植物可能会开花。