mesofauna

Mesofauna are small soil-dwelling invertebrates occupying a size class between microfauna and macrofauna. They are typically about 0.1 to 2 millimeters long, living in soil pore spaces, litter, and decomposing organic matter. Their small size means they are usually studied by extracting organisms from soil or litter samples rather than by direct observation.

The most abundant mesofauna are mites (Acari) and springtails (Collembola). Other tiny groups, including some enchytraeid worms and diminutive crustaceans, may also be classified as mesofauna. Together they form a vital link between microorganisms and larger soil fauna within the soil food web.

Roles include feeding on fungi, bacteria, detritus, and other tiny animals; accelerating litter breakdown; contributing to nutrient mineralization; and influencing soil structure through movement and fecal pellets. They interact with fungi and bacteria and can affect community composition and ecosystem processes such as decomposition rates.

Environmental conditions strongly shape mesofaunal communities. Moisture, temperature, pH, organic matter, and texture influence their abundance and composition. They are sensitive to drying and intensive tillage and often respond rapidly to management practices. Because of this, mesofauna are frequently used as indicators of soil health and habitat disturbance.

Study methods include extraction from soil using Berlese-Tullgren funnels or heat, wet sieving of litter, and microscopy or DNA-based identification. Metrics such as abundance, biomass, species richness, and feeding relationships are used to characterize assemblages and their function in soil ecosystems.