Studying the Metabolic Rates of Lobster Larvae

Adrian Javier Contreras

This summer, I am working with Dr. David Fields and Maura Niemisto at Bigelow Laboratory for Ocean Sciences. I am conducting a full factorial experiment with a two-way ANOVA. This means I can examine every combination of my variables, to determine the effects of ocean acidification and high temperature on the metabolic rates of lobster larvae. I hypothesize that the most extreme conditions will cause the most adverse effects on lobster larvae, provided we do not feed them. My hypothesis also states that the Rhode Island larvae will have a higher dry weight and more lipid (fat) content than Midcoast Maine larvae due to them coming from mothers already exposed to climate change.

The image above shows planktonic lobster larvae which are vulnerable to different changes in the environment at this stage of development. After stage IV they sink down to the benthic zone. Larvae are vulnerable to disease, predation, and the water column is a very versatile environment. Therefore, it is important to study lobsters at this stage to understand what consequences could come from climate change.

This is especially important for fisheries that capture the American Lobster, because lobster fishing is a big business on the East Coast. The peak abundance of lobster populations is moving northward. This means that higher abundances of lobsters are being reported in colder climates. This project is important because fisheries benefit from understanding where lobsters are migrating and why. Population shift creates biological and ecological impacts — and will also create an economic impact.

By the end of my experiment, my data will show if it is important to keep track of which mother the larvae came from. This is due to mothers possibly passing down different lipid content to their offspring. My results could show that Rhode Island mothers produce offspring that have similar lipid content and dry weights compared to Midcoast larvae. My experiment could potentially show the impacts of varying climates on the rate of lipid consumption of larvae. The diagrams below show Maine lobsters and Rhode Island Lobsters. Rhode Island larvae began at a very similar dry weight while Maine produced larvae with varying dry weights. This could possibly be due to climate change. Future studies could look into this question more closely.

The hardest part of this experiment is to conduct many tasks each day. I have a 6-day experiment where I perform Oxygen Consumption Rate measurements (OCR), and select larvae for lipid analysis, and Carbon Nitrogen analysis. I perform daily water changes and make sure that our readings are stable. In addition, I have four treatments with larvae from 3 different mothers to take care of. My treatments are 4 baths calibrated at 4 different environments. I have each bath at a specific temperature and a specific amount of pCO2 is pumped into each bath to mix with the water and allow for the pH to change. The ambient conditions for larvae is 400ppm at 16C. However, by adjusting temperature and the pCO2, I can create artificial environments to test the potential effects of these stressors on larvae. End-century predicted conditions are expected to reach 1200ppm at 19C. Furthermore, my water quality checks require my 1200ppm treatments be at a pH of 7.77, while my 400ppm treatments must be at a pH of 8. I must keep track of the values to ensure everything is consistent. However, I am often reminded everything is not always exact in science. Therefore, I take my best estimate or make my own decisions on where this experiment goes.

Since day one, I knew I would be conducting independent research. Luckily, I have a graduate student, Maura, to consult with and help me whenever I am not confident about certain readings or procedures. Furthermore, I read research articles on similar experiments, which was difficult because of all the scientific language I am unfamiliar with. Although a few aspects of this internship are stressful, it has been a fun experience. I like to roam around the lab and look at the different projects other interns are performing, and help where I can. I also enjoy working with new instruments and learning new skills to take with me.

All in all, conducting research has been rewarding. Every day, I show up and expect orders or a list of things to do, but then remember that I oversee everything and that I should only go to Maura for consultations. In the end, I am excited to see what data I collect and what conclusions this data shows. I am learning to become more decisive and better at collecting data. These past months at Bigelow Laboratory have made me a better student and biologist.

This figure shows each jar color coded to keep track of the larvae and which mother they came from. This bath is calibrated to 400ppm at 16C.

Adrian Javier Contreras is a Palomar Community College student in Bigelow Laboratory for Ocean Science’s Research Experience for Undergraduates program. This intensive experience provides an immersion in ocean research with an emphasis on hands-on, state-of-the-art methods and technologies.

Studying the Metabolic Rates of Lobster Larvae