What do you do once you've processed the sediment samples?

Nematode dyed with bengal rose surrounded by sediment grains and other benthic material.

Originally for this week's blog post, I wanted to upload a video recording of the work that I do in the lab to sort nematodes from the surrounding sediment after I have passed them through the sieve and centrifuged them. However, that's not currently a possibility, so instead I'll use the reference photo to describe a little about the third step of meiofauna research at the lab.

If you haven't seen my previous posts, the first two steps of doing meiofauna research are: 1. collecting sediment cores from the field, and 2. processing the sediment cores by passing the sediment through a sieve and then centrifuging the sediment to extract meiofauna through density separation. Before samples are ready for step three, I apply a bengal rose dye, which colors the nematodes and other meiofauna pink, which can be seen in the photo to the right. The bengal rose, in my opinion, is extremely useful for the third step of meiofauna research, which is the extraction step.

In the extraction step of my research, I pour out the centrifuged meiofauna into a petri dish and using very small tools with hooks transfer a number of nematodes from the petri dish to an embryo dish. The number of nematodes that we generally extract per sample in the lab is 120, though this may vary based on the project. Nematodes, like many meiofauna, are clear organisms and are easily hidden by the sediment and other organic and inorganic materials that end up in the sediment, so the bengal rose dye makes the nematodes apparent for extraction. 

Next week I will show a comparison of nematodes and other similar-looking meiofauna, but one identifying characteristic of nematodes is their body shape or structure. As you can see in the photograph, the nematode has a tapered mouth and tail but is not segmented. Although some nematode taxa have a grooved appearance (Desmoscolex), many appear like the individual in the photograph; no matter their size, whether a nematode looks like a long tangled string or a miniature banana, I extract them from the sample to prepare for part four of the research.

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