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Purpose <p>This study evaluated how the biochemical composition of sediments and organic matter inputs (from cyanobacterial blooms and riparian vegetation) shape the structure and diversity of methanogenic archaeal communities in two South American subtropical reservoirs (Bonete and Palmar), influencing CH<sub>4</sub> production rates.</p> Methods <p>Sediments collected near the dam areas of both reservoirs were incubated under anaerobic conditions with or without dried <i>Microcystis</i> spp. bloom material and riparian pasture. Biochemical composition (proteins, lipids, carbohydrates, and biopolymeric carbon), total nitrogen, and phosphorus were analyzed. Archaeal communities were characterized using 16S rRNA gene sequencing targeting the V4–V5 region. Alpha diversity, correlation analyses, PCA, and dbRDA were used to evaluate relationships among community composition, CH<sub>4</sub> production, and sediment chemistry, while differential abundance analyses were performed to identify OTUs associated with sample groupings along the first and second dbRDA axes.</p> Results <p>Palmar sediments hosted a richer and more diverse archaeal community than Bonete, associated with higher protein and biopolymeric carbon content. Incubations with <i>Microcystis</i> and pasture reduced alpha diversity and favored <i>Methanosarcina</i> and <i>Methanobacterium</i>, both strongly correlated with CH<sub>4</sub> production rates (<i>r</i> = 0.85, <i>p</i> = 0.008 and 0.81, <i>p</i> = 0.015, respectively) and nutrient-rich conditions. Conversely, the methanotroph <i>Candidatus Methanoperedens</i> and diversity indices correlated negatively with biopolymer concentration. dbRDA confirmed the strong influence of substrate origin and composition on community structure.</p> Conclusion <p>The biochemical quality and quantity of sedimentary organic matter determined archaeal diversity and activity. Increased biopolymer content, typical of eutrophic systems affected by blooms, promoted specialized methanogenic genera and enhanced CH<sub>4</sub> production, implying that eutrophication and organic enrichment can intensify greenhouse gas emissions from reservoirs and contribute to global warming.</p>

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Biopolymer composition shapes methanogenic archaeal communities in sediments from eutrophic subtropical hydroelectric reservoirs

  • 期刊论文

  • 发表日期：

    2026年6月16日

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  • Mauricio González-Piana,
  • Emiliano Pereira,
  • Ana Fernández-Scavino,
  • Luciana Pereira-Mora,
  • Donato Seiji Abe,
  • Corina Sidagis,
  • Sol De Giacomi,
  • Julieta Cuevas,
  • Guillermo Chalar

摘要

Purpose

This study evaluated how the biochemical composition of sediments and organic matter inputs (from cyanobacterial blooms and riparian vegetation) shape the structure and diversity of methanogenic archaeal communities in two South American subtropical reservoirs (Bonete and Palmar), influencing CH4 production rates.

Methods

Sediments collected near the dam areas of both reservoirs were incubated under anaerobic conditions with or without dried Microcystis spp. bloom material and riparian pasture. Biochemical composition (proteins, lipids, carbohydrates, and biopolymeric carbon), total nitrogen, and phosphorus were analyzed. Archaeal communities were characterized using 16S rRNA gene sequencing targeting the V4–V5 region. Alpha diversity, correlation analyses, PCA, and dbRDA were used to evaluate relationships among community composition, CH4 production, and sediment chemistry, while differential abundance analyses were performed to identify OTUs associated with sample groupings along the first and second dbRDA axes.

Results

Palmar sediments hosted a richer and more diverse archaeal community than Bonete, associated with higher protein and biopolymeric carbon content. Incubations with Microcystis and pasture reduced alpha diversity and favored Methanosarcina and Methanobacterium, both strongly correlated with CH4 production rates (r = 0.85, p = 0.008 and 0.81, p = 0.015, respectively) and nutrient-rich conditions. Conversely, the methanotroph Candidatus Methanoperedens and diversity indices correlated negatively with biopolymer concentration. dbRDA confirmed the strong influence of substrate origin and composition on community structure.

Conclusion

The biochemical quality and quantity of sedimentary organic matter determined archaeal diversity and activity. Increased biopolymer content, typical of eutrophic systems affected by blooms, promoted specialized methanogenic genera and enhanced CH4 production, implying that eutrophication and organic enrichment can intensify greenhouse gas emissions from reservoirs and contribute to global warming.