Meiofauna Sample Collection, Transportation, Storage, and Processing Techniques

Meiofauna are small, microscopic invertebrates that live in sediments of both marine and freshwater environments. They play an important role in nutrient cycling, bioturbation and are a source of food for higher organisms in the higher trophic levels. They can serve an important role as indicators of ecosystem health. However, baseline studies are missing for most aquatic habitats, particularly marine environment. Coring is the widely recommended technique in collecting field data. The coring is done using a corer of 3.4 cm internal diameter. Immediately after collection, sediment samples are fixed with 8% formalin. In the lab, the sample is first washed over a set of 1 mm and 38 mm sieves with a gentle jet of water. The content retained over the 38mm sieve is then subjected to a decantation process to remove sand and other heavy detritus. The sample from the 38mm sieve is put in a 5-liter jar and the material is stirred well using a gentle jet of water. It is then left to settle for a few seconds and poured over the sieve (38mm). This is followed by centrifugation at 3000 rpm for 30 minutes using hydrated Magnesium Sulphate (MgSO4.H2O) solution with 1.25g/cm3 and 1.28g/cm3 specific density. Counting is facilitated by staining the entire sample with a few drops of Rose Bengal solution. Identification and counting of specimens is done under a dissecting microscope at a minimum of 25X magnification up to class level. The data obtained help in understanding meiofauna species composition, distribution and abundance which inform the ecological status of the aquatic ecosystems. This paper demonstrates DOs and DONTs when conducting meiofauna studies.