Observing Interactions Between Marine Snow and Tethered and Free-swimming Copepods

Hennessy Martinez, Mater Dei Catholic High School, Chula Vista, CA, United States, Jennifer C. Prairie, University of San Diego, Environmental and Ocean Sciences, San Diego, CA, United States, Thomas Drake, University of San Diego, San Diego, United States and Christian Briseño-Avena, University of San Diego, Department of Environmental and Ocean Sciences, San Diego, CA, United States
This past summer, I had the opportunity to be a 2019 Summer Research Scholar as part of the Bridging the Gap program at the University of San Diego through a partnership with my high school, Mater Dei Catholic High School. Through this opportunity, I worked under the mentorship of Dr. Prairie and Dr. Briseño-Avena, gaining valuable experience in both lab and field research, including collecting copepods in the field, performing lab experiments with live copepods, and working collaboratively with undergraduate and graduate students. The goal of my project was to study how copepods interact with and ingest marine snow aggregates through high-resolution imaging. This research demonstrates how small organisms like copepods can contribute to the large-scale cycling of carbon through the biological pump.

In our experiments, we observed the copepod Calanus pacificus interact with marine snow aggregates formed in the laboratory from cultures of the diatom Thalassiosira weissflogii. Throughout the summer, we conducted experiments with both tethered and free-swimming copepods. Tethering allowed us to keep the copepods in the small field of view of the camera. The experiment with free-swimming copepods allowed us to investigate whether tethering had any effects on the copepod’s interaction with the marine snow aggregates. Different issues arose in both the tethered and free-swimming experiments. The tethered copepods were somewhat limited in their movement which may have affected their ability to normally interact with the marine snow aggregates that were sinking through the tank. In the free-swimming experiment, the copepods mostly hid in the corners of the tank, and we were unable to directly observe interactions with marine snow. Here we will present observations from both experiments and discuss future directions.