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# Toxic Microcystis blooms did not carry one repeatable microbial signature across Guatemala and Poland
- URL: https://intelligence.wildlandseco.com/2026-10-02-guatemala-poland-microcystis-bacterial-communities/
- Published: 2026-10-02T13:48:44.000Z
- Updated: 2026-10-02T13:48:44.000Z
- Description: Three freshwater systems differed sharply in cyanobacteria, microcystins and associated bacterial communities, with catchment nutrients and seasonal context shaping the pattern.
- Author: Benjamin Worlund
- Tags: Microcystis, cyanobacterial blooms, microcystins, Guatemala, Poland, Water, One Health, microbiomes, Land use, #ecological-intelligence, #brief-2026-10-02, #global-radar, #peer-reviewed, #geo-transregional

Evidence

Peer-reviewed

Geography

Lake Amatitlán and Laguna del Pino, Guatemala; Sulejów Reservoir, Poland

System

Freshwater lakes and reservoirs

## WHAT THE EVIDENCE SAYS

A comparative study sampled hypertrophic Lake Amatitlán and mesotrophic Laguna del Pino in Guatemala and eutrophic Sulejów Reservoir in Poland. Lake Amatitlán was dominated by Microcystis and had the highest measured microcystins—20.39 and 47.68 µg/L at the urban- and agricultural-catchment sites—while lower-nutrient Laguna del Pino was diatom-dominated with no detected microcystins. Sulejów shifted seasonally among cyanobacterial assemblages. 16S sequencing showed distinct associated bacterial communities among lakes and seasonal stages.

## WHY IT MATTERS / OUR READ

Harmful-bloom monitoring benefits from treating the catchment, cyanobacteria, toxins and microbiome as one changing system. The label ‘Microcystis bloom’ can conceal very different nutrient context, toxicity and bacterial associates.

## CAVEATS / UNCERTAINTY

The comparison includes only three freshwater systems and different seasonal sampling contexts, so climate zone, land use, trophic state and season cannot be cleanly separated. Community associations do not establish causal microbial interactions or predict toxicity at unsampled times.

## SOURCE

Hydrobiologia — primary study  
[View original evidence ↗](https://doi.org/10.1007/s10750-026-06375-w?ref=intelligence.wildlandseco.com)

From the Morning Brief · 2026-10-02

[Read the full Morning Brief →](https://intelligence.wildlandseco.com/morning-brief-2026-10-02/)