Freshwater Microbiomes, Iron Oxidation, and Harmful Algal Blooms

Practice vocabulary flashcards covering freshwater microbial ecology, anthropogenic water features, microbially influenced corrosion (MIC) by iron-oxidizing bacteria, harmful algal blooms (HABs), and aquaculture economics.

Lithotrophic Iron-Oxidizing Bacteria (FeOB)

Microorganisms that depend on reduced iron, $Fe(II)$, as their primary energy source, commonly growing on steel infrastructure and contributing to microbially influenced corrosion (MIC).

Lithoautotrophy (in FeOB)

A metabolic strategy wherein organisms utilize the energy obtained from the oxidation of reduced iron ($Fe$) to fix carbon dioxide ($CO_2$).

Heterotrophic Iron Oxidation

A process in which organisms catalyze the oxidation of iron but do not conserve energy from the reaction nor fix $CO_2$, instead utilizing organic matter for carbon and energy.

Microbially Influenced Corrosion (MIC)

The deterioration and pitting of metallic infrastructure (such as well water production pipes and steel surfaces) driven by microbial activity, chemical gradients, and biofilm formation.

FeOB Stalk

An extracellular structure composed of polysaccharides that has a protective function against toxic oxygen radicals formed during chemical iron oxidation.

Gallionella ferruginea

A dominant species of lithotrophic iron-oxidizing bacteria that forms prominent microbial mats (large biofilms) and twisted extracellular stalks in open subsurface ponds and plumbing systems.

Quarry Lakes

Man-made lakes formed after mining activities cease and disused excavation sites fill with rainwater and/or groundwater, typically harboring acidophilic, metal-tolerant microbes and exhibiting steep oxygen gradients.

Legionella

A waterborne bacterial pathogen that lives and proliferates within biofilms in cooling towers and plumbing systems, causing severe and potentially fatal lung infections in humans.

Cooling Towers

Industrial installations used for data centers and HVAC climate control that require freshwater to prevent pipe fouling or corrosion, but are prone to colonization by waterborne pathogens.

Extracellular Polymeric Substances (EPS)

Microbially secreted polymers that provide structural integrity to biofilms, regulate pore spacing and hydraulic conductivity, protect against erosion, and facilitate particle settling as marine snow.

Lake Baikal Microbiome

A bathypelagic freshwater ecosystem where bacterial abundance peaks at the surface, cyanobacteria dominate during summer, and oligolithotrophic bacteria (Rhodospirillaceae, SAR202 Chloroflexi, or Nitrosopumilaceae) predominate in colder seasons.

Harmful Algal Blooms (HABs)

Rapid proliferations of phytoplankton (prokaryotic cyanobacteria or eukaryotic algae) that toxify aquatic systems, contaminate the air, deplete commercial and recreational fishing, and are exacerbated by warming waters.

CyanoHAB Dominant Genera (United States)

The three primary cyanobacterial genera responsible for toxic blooms in freshwater environments across the United States: Microcystis, Dolichospermum (formerly Anabaena), and Planktothrix.

Microcystis aeruginosa

The dominant toxigenic cyanobacterium in interior riverine and reservoir systems, responsible for recurrent, massively destructive toxic blooms in Lake Erie.

Microcystins

Hepatotoxic chemical toxins produced by cyanobacteria during blooms that can cause severe illness or death in humans, livestock, pets, fish, birds, and other wildlife.

Non-Point Source Phosphorus Loading

Agricultural runoff supplying excess phosphorus ($P$) that acts as the primary environmental driver of harmful cyanobacterial blooms in the western basin of Lake Erie.

Cyanobacteria-Heterotroph Nitrogen Symbiosis

A mutualistic interaction occurring when external nitrate is exhausted; heterotrophic bacteria ammonify and regenerate organic nitrogen ($N$) for Microcystis, while Microcystis supplies organic carbon ($C$) to the heterotrophs.

DNA-Based HAB Monitoring

A molecular detection method offering high sensitivity to identify causative phytoplankton species and differentiate morphologically identical toxigenic from non-toxigenic strains.

Economic Burden of Waterborne Illness in Canada (2012)

The estimated annual economic cost of illnesses caused by waterborne pathogens in Canada, valued at approximately $\$2.7\text{B}$ in 2012.

Canadian Aquaculture Industry (2024–2025 Statistics)

A marine and freshwater sector generating $\$6\text{ Billion}$ in economic activity, $\$2.27\text{ Billion}$ in GDP, $160{,}318\text{ tonnes}$ of production value ($\$1.36\text{ billion}$), and exporting $94\%$ of its exports to the United States.

Actinobacteria

Found in all fish but catfish

Farm raised fish vs. wild fish

Farm-raised fish has a different and higher microbial diversity

Most common HABs

CyanoHABs, microcystis, dolichospermum and planktothrix

Hepatotoxin

Produced by microcystin, most toxic are LR and LA