Endobenthos Collection

Today was our last class dive of the semester. During this dive we collected endobenthos samples. Benthos are flora or fauna on or in the bottom of a body of water. There are two types of benthos; epibenthos and endobenthos. Epibenthos are benthic organisms that live on or move over the substrate surface, whereas, endobenthos are organisms that move within the sediment displacing particles. It is important to study benthos because these organisms are: 1) bioindicators of health; 2) play important ecological roles filter particles, breaking down organic matter, and removing sediment allowing water exchange; 3) study life histories of fauna; and 4) important component of a variety of ecosystems. There are a number of different sampling types and we did the manual core sampling technique. To collect the sample, we took a piece of PVC and worked it into the sand to a specific depth. This involved us having to take a vertical position in the water swimming downwards to work the PVC into the sand. We then worked the PVC back out and capped the sample. After all the samples were collected, we headed back to the lab to sieve, relax, stain, and dry the samples for further data analysis. Relaxation of the sample is done by using magnesium chloride to reduce the tendency of organisms to distort their shape. Staining facilitates sorting and increases sorting accuracy because a person can see more of the organisms. We used rose bengal (pink dye) to stain the samples. We also place some of the samples in the oven to dry to do more sieving to sort the different particle sizes for granulometry analysis. Later this week, we will remove the samples from the oven to sort out the different particle sizes and to collect the stained organisms from the samples with the rose bengal.