Biomass For Meiofauna

This week at the lab I moved onto the next phase of wrapping up the mesocosm experiment: biomass measurements. Biomass, as the name suggests, is the weight of any organism, and this metric is common in fields of ecology and agricultural science. While most scientists collect biomass measurements by weighing the organism and then drying the organism out to get a dry weight, this process is often not suitable for meiofauna research given the size of organisms involved. A quick Google search tells me that larger individual nematodes can weigh between 0.04 and 8 micrograms, which would be painstaking to mass each individual. Instead, researchers developed a suitable biomass calculation for all meiofauna individuals. This method involves using biovolume measurements and conversion factors to calculate biomass. Here's how the process works: 1) individual animals are either photographed or mounted on slides for microscopic analysis; 2) body measurements are collected from the animal, usually length and width measurements, from the photographs or from software connected to the microscope; 3) biovolume measurements are calculated by multiplying the length x width^2 x conversion factor, and these conversion factors are specific to the types of animals and vary based on body shapes for some animals; 4) finally, these biovolume measurements are converted to wet weights and then dry weights using additional conversion factors, which have been validated by researchers.

At the lab this week, I finished extracting all the meiofauna from my samples and I am currently making slides for all the animals. During the slide making process, I am also photographing all the slides to take biovolume measurements. This photography and calculation process is made much easier since the microscope at the lab has a fixed zoom, where I can set the zoom and it will not move, guaranteeing consistent distances to compare to the reference photograph for scale. The photographic measurements are also quite helpful since I can upload the photos and complete the measurements elsewhere, rather than staying at the lab extra hours during the week. The entire process of making slides, photographing samples, and collecting biomass measurements for the meiofauna will likely take the entirety of October, although using a photographic analysis rather than the in-person microscope software analysis saves a few weeks of time. Once I finish the meiofauna measurements I will move on to the macrofauna, which will be a whole other beast and a different biomass measurement process altogether.

​Stay tuned!