Alpha and beta diversity estimates.

Oxygen minimum zones (OMZ) represent ~8% of the ocean, with the Pacific as the largest and top expanding area. These regions influence marine ecosystems, promoting anaerobic microbial communities. Nevertheless, only a fraction of microbial diversity has been studied, with fungi being the less explored component. So, herein we analyzed fungal diversity patterns in surface and subsurface sediments along a bathymetric transect using metabarcoding of the ITS1 region in the OMZ of the Mexican Pacific off Mazatlán. We identified 353 amplicon sequence variants (ASV), within the Ascomycota, Basidiomycota, and Rozellomycota. Spatial patterns evidenced higher alpha diversity in nearshore and subsurface subsamples, probably due to temporal fluctuations in organic matter inputs. Small-scale heterogeneity characterized the community with the majority of ASV (269 ASV) occurring in a single subsample, hinting at the influence of local biogeochemical conditions. This baseline data evidenced a remarkable fungal diversity presenting high variation along a bathymetric and vertical transects.氧最小值区（Oxygen Minimum Zones, OMZ）约占海洋总面积的8%，其中太平洋是规模最大且扩张速度最快的区域。此类区域可对海洋生态系统产生影响，促进厌氧微生物群落的发育。然而，当前仅对极小部分微生物多样性开展了研究，而真菌则是其中研究程度最低的类群。为此，本研究针对墨西哥马萨特兰附近东太平洋氧最小值区的沉积物，利用ITS1区域宏条形码技术（metabarcoding），对沿水深断面分布的表层及次表层沉积物中的真菌多样性模式展开分析。研究共鉴定出353个扩增子序列变异体（amplicon sequence variants, ASV），分属于子囊菌门（Ascomycota）、担子菌门（Basidiomycota）与罗兹菌门（Rozellomycota）。空间分布特征显示，近岸区域及次表层沉积物样本的α多样性更高，这可能与有机质输入的时间波动相关。该真菌群落呈现出显著的小尺度异质性特征，绝大多数ASV（共269个）仅在单个样本中被检测到，这提示局地生物地球化学条件对群落结构存在调控作用。本研究获取的基线数据表明，该区域真菌多样性极为丰富，且在水深与垂直断面上均存在显著的空间变异。