Extracting aquatic mites from stream substrates: a comparison of three methods

Area of Science:

• Aquatic ecology
• Acarology
• Freshwater invertebrate sampling

Background:

• Aquatic mites (Hydrachnida, Oribatida, Halacaroidea) are diverse and abundant in stream substrates.
• Their small size often leads to them being overlooked in ecological surveys.
• Understanding efficient extraction methods is crucial for accurate biodiversity assessments.

Purpose of the Study:

• To compare the thoroughness and time-efficiency of three extraction methods for aquatic mites from stream substrates.
• To identify the optimal method for surveying diverse acarofauna, including smaller taxa like oribatids and halacarids.

Main Methods:

• Live-picking: sorting live samples without magnification.
• Microscope-picking: exhaustive sorting of preserved samples using a dissecting microscope.
• Kero-float: kerosene-flotation of preserved samples followed by sorting with a dissecting microscope.

Main Results:

• Live-picking yielded significantly fewer individuals and species, biased towards larger mites.
• Oribatids and halacarids were missed with live-picking.
• Live-picking and kero-float showed similar time-efficiency, while microscope-picking was less efficient than kero-float.

Conclusions:

• A combination of live-picking and kerosene-flotation is recommended for comprehensive stream acarofauna surveys.
• This combined approach improves the detection of diverse mite species and overall sample thoroughness.