The hidden architects of aquatic ecosystems: ecosystem services provided by diatoms

by Kálmán Tapolczai |

This is a summary of the scientific article published in Hydrobiologia (B-Béres et al. 2023)

Diatoms, microscopic algae found in freshwater and marine environments, are some of the most ecologically significant organisms on Earth. Despite their small size, their impact on global ecosystems and human well-being is enormous. As a major component of aquatic food webs, diatoms contribute to primary production, climate regulation, and industrial applications. Their roles can be classified into four categories of ecosystem services: supporting, regulating, provisioning, and cultural services, as outlined by the Millennium Ecosystem Assessment (MEA, 2005). Understanding these services highlights the importance of diatoms and emphasizes the need for their conservation.

Supporting services: the foundation of aquatic ecosystems

Diatoms are primary producers, converting sunlight into organic matter through photosynthesis, forming the base of aquatic food chains. They are responsible for an estimated 20–40% of global primary production, producing vast amounts of oxygen essential for life on Earth. Additionally, diatoms play a key role in nutrient cycling, particularly in the carbon and silicon cycles. Their silica-based cell walls (frustules) contribute significantly to sediment formation, aiding in the geological process of diatomaceous earth accumulation. Another crucial supporting service is habitat provisioning. Diatoms create microhabitats within aquatic ecosystems, offering surfaces for bacteria, fungi, and meiofauna to thrive. Benthic diatoms, which colonize sediments and submerged surfaces, contribute to periphyton communities that serve as both food and shelter for aquatic organisms.

Regulating services: nature’s engineers

One of the most critical regulatory functions of diatoms is climate regulation. They sequester vast amounts of carbon by fixing CO₂ during photosynthesis, with an estimated 40% of oceanic carbon sequestration attributed to diatoms. Furthermore, marine diatoms contribute to cloud formation by releasing dimethylsulfide (DMS), a compound that influences atmospheric chemistry and helps cool the planet. Diatoms also contribute to sediment stabilization and erosion control. The biofilms formed by benthic diatoms help stabilize sediments, preventing erosion in rivers, lakes, and coastal areas. Additionally, diatoms assist in biological control and wastewater treatment, as they efficiently absorb nutrients, heavy metals, and pollutants from aquatic environments. Their role in nitrogen storage and nutrient cycling makes them essential for maintaining water quality and reducing harmful algal blooms.

Figure 1. Supporting and regulating ecosystem services provided by marine diatoms and some of their negative impacts; CNN – cloud condensation nuclei; DMS – dimethylsulphide; DMSP – dimethylsulphoniopropinate; VOCs – volatile organic compounds. Better quality image here. 

Provisioning services: benefits for humanity

Diatoms provide numerous direct benefits to humans through biochemical and industrial applications. Their silica cell walls make them invaluable in micro- and nanotechnology, with applications ranging from drug delivery systems to semiconductors. NASA has even explored diatom-based wastewater treatment for space missions, highlighting their biotechnological potential. In the pharmaceutical and food industries, diatoms contribute to the production of polyunsaturated fatty acids (PUFAs), antioxidants, and bioactive compounds with potential antibacterial and anti-cancer properties. Their high nutritional value makes them an essential food source in aquaculture, particularly for early-stage fish and shellfish larvae. Diatomaceous earth, derived from fossilized diatoms, has widespread industrial applications. It is used as a filtration aid, insecticide, insulation material, and even as an additive in cement and paints. Historically, diatomite played a crucial role in the production of dynamite, as Alfred Nobel discovered its ability to absorb nitroglycerin safely.

Cultural services: inspiration and scientific value

Diatoms have also contributed to cultural and educational fields. Their intricate, glass-like structures have fascinated scientists, artists, and designers for centuries. The famous German biologist Ernst Haeckel illustrated diatoms in his “Kunstformen der Natur,” emphasizing their aesthetic and symmetrical beauty. Even today, diatoms inspire artworks, jewellery, and architectural designs. Beyond aesthetics, diatoms are invaluable in scientific research and forensic science. Their presence in water bodies serves as a bioindicator for water quality assessment. Additionally, diatom analysis is used in forensic investigations, particularly in drowning cases, where the presence of diatoms in human tissue can help determine the circumstances of death. Diatoms are also gaining recognition in environmental education and citizen science initiatives. Projects such as Diatoms of North America or the International Society for Diatom Research, and public exhibitions help raise awareness about these microorganisms and their importance in maintaining ecological balance.

Figure 2. Diatom models made for the algology course by undergraduate students at University of Pannonia, Hungary

Challenges and conservation needs

Despite their ecological and economic significance, diatoms face threats from climate change, habitat degradation, and pollution. Rising global temperatures and increased water retention in large rivers can alter diatom community structures, reducing biodiversity and affecting ecosystem stability. Harmful algal blooms (HABs) can disrupt the balance in aquatic environments. Some marine species can cause toxic diatom blooms that produce domoic acid, a neurotoxin that affects marine mammals and shellfish consumers. Invasive diatom species are another growing concern. The mass proliferation of e.g. Didymosphenia geminata or Cymbella janischii may alter the structure of biological communities or cause harm in the domestic water infrastructure, foul fishing nets and degrade the recreational values of aquatic ecosystems.

Conclusion

Diatoms are more than just microscopic algae; they are key players in global ecosystems, providing essential services that support life on Earth. From oxygen production and carbon sequestration to biotechnology and environmental monitoring, diatoms contribute to multiple facets of human and ecological well-being. However, increasing environmental pressures threaten their populations, underscoring the need for conservation and sustainable water management. Recognizing and protecting the invaluable ecosystem services provided by diatoms is crucial for maintaining biodiversity and ecological stability. As scientific research continues to uncover new applications for these remarkable microorganisms, their role in shaping the future of both natural ecosystems and human industries will only become more significant.

REFERENCES

B-Béres, V., Stenger-Kovács, C., Buczkó, K. et al. Ecosystem services provided by freshwater and marine diatoms. Hydrobiologia 850, 2707–2733 (2023). https://doi.org/10.1007/s10750-022-04984-9

MEA 2005 Millennium Ecosystem Assessment, 2005. Ecosystems and human well-being: biodiversity synthesis, World Resources Institute, Washington, DC