Brejo do Espinho coastal lake (LBE) is one of the few places in the world where dolomite [CaMg(CO₃)₂] is precipitating in the modern environment under microbially induced processes and low oxygen conditions. We use pore morphometry of the foraminifera Ammonia cf. A. veneta to evaluate paleo-O₂ dynamics during the dolomitic depositional phase that took place at LBE in the late Holocene. Foraminiferal community structure was also investigated, and results were compared to bulk isotopic composition of carbonates, total organic carbon (TOC), and X-ray Diffraction of sediments (XRD). The correlation matrix (Spearman method) showed that Ammonia test pores morphometric parameters displayed significant correlations with overall biotic and geochemical data, with pore area presenting a relatively higher association. Ammonia test pores were primarily controlled by the degradation of organic matter (Pore area-TOC, r = −0.84), and foraminifera density appeared to be influenced by oxygen changes, with a higher abundance in the highest porosity intervals (Pore area-N, r = 0.82), indicating a direct effect of oxygen penetration on species dominance. These data also reveal a tolerant behavior of the low-O₂ bioindicator species Quinqueloculina laevigata and A. veneta. Understanding microbe-mineral interactions is critical for interpreting paleo records, and our data provide strong support for coupling assemblage and pores analysis as paleo-O₂ bioindicators for paleo-redox coastal settings.

Brejo do Espinho 沿海湖 (LBE) 是世界上少数几个白云石 [CaMg(CO ₃ ) ₂ ] 在现代环境中在微生物诱导过程中沉淀的地方之一。低氧条件。我们使用有孔虫氨的孔隙形态测定法。 A. veneta 评估全新世晚期 LBE 发生的白云岩沉积阶段的古 O ₂ 动力学。还研究了有孔虫群落结构，并将结果与​​碳酸盐的本体同位素组成、总有机碳 (TOC) 和沉积物的 X 射线衍射 (XRD) 进行比较。相关矩阵（Spearman法）显示，氨测试孔隙形态参数与整体生物和地球化学数据表现出显着的相关性，其中孔隙面积呈现相对较高的关联性。氨测试孔隙主要受有机质降解控制（孔隙面积-TOC，r = -0.84），有孔虫密度似乎受到氧气变化的影响，在最高孔隙度区间（孔隙面积-N， r = 0.82），表明氧气渗透对物种优势的直接影响。这些数据还揭示了低 O ₂ 生物指示剂物种 Quinqueloculina laevigata 和 A. veneta 的耐受行为。了解微生物-矿物相互作用对于解释古记录至关重要，我们的数据为耦合组合和孔隙分析作为古氧化还原沿海环境的古 O ₂ 生物指示剂提供了强有力的支持。