April 2023 – Clay Carbon Ocean

Interactions between zooplankton and clay

Manasi is investigating whether clay minerals are ingested by zooplankton species such as copepods and are transported to deeper waters via fecal pellets. Copepods are the most abundant mesozooplankton taxa in the marine environment and represent a vital link in the marine food web between algae and higher predators such as fish, whales etc. Fecal pellets produced by copepods are an important nutrient source for deep water ecosystems and can rapidly transport organic matter to the ocean floor. Fecal pellet production rates of actively feeding copepods may exceed 10 pellets per hour.

Day 10: Back to Dartmouth

On our last morning on R/V Endeavor we spent the morning finishing packing up the lab, offloading our supplies, and Tetris-ing everything back into the van. By early afternoon we were ready to start the trip back, first stopping in East Providence to buy dry ice for preserving some of our samples. On the way we observed a very hazardous situation in which a pickup truck was pulled over on the side of the road and appeared to be leaking gas which was forming a small puddle on the ground. The puddle was on fire, and there was an intense burning odor as we passed by.

We stopped at an Indian restaurant in Cambridge for an early dinner, and sitting beside the floor-to-ceiling windows we people-watched as we ate. The weather was nice today as well and we hoped it would feel like spring in Hanover when we returned.

Day 9: Return to Narragansett

We had beautiful weather for the return to the dock at URI, and many of us took turns standing outside to take in the sun and to observe the tugboat that helped us maneuver into place. As you can see in the photo, it met up with us and trailed us for a little while before we approached the dock.

Day 8: Almost Done

After spending the last couple days monitoring the incubation experiment, it was time to take it down and sample for final parameters. After breakfast we took all the bottles out of the incubator and brought them into lab, again very careful not to disrupt any stratification or flocs (loosely packed particle masses) within them.

The final parameters took much longer than the initial parameters – when starting the experiment we only had 3 different types of water, the 3 different size fractions of phytoplankton. But now that they had undergone incubation and treatment we had to sample final parameters from all 27 bottles.

Day 5: Spraying Clay

Our phytoplankton bottles had the spent the night in the incubator (kindly provided by the UConn team), a water bath on deck that allows access to sunlight and keeps the temperature consistent with that of the surface seawater. Now that the plankton had time to adjust to being inside the bottles, 18 of the 27 bottles were ready to undergo the experimental clay treatments (the other 9 were control groups).

To properly investigate the effects of the clay additions on the phytoplankton, Diksha and Vignesh had created a slurry before the cruise with a known amount of clay. This slurry, however, could not simply be poured into the bottles. That would be too easy. Instead we needed a way to gently and evenly distribute the slurry over the surface of the water inside the bottles.

Day 4: The Real Work Starts Today

We spent the morning of the 4th day making sure that everything was in place for our phytoplankton incubation experiment to begin, the main reason we were on the Endeavor in the first place. Diksha and Vignesh had spent the weeks leading up to the cruise planning it all out and finally it was about to happen. With the towfish in place and all the bottles pre-labeled, we were ready to start collecting seawater.

The fish was deployed around 1300 – it took two of us plus two Endeavor crew members to get the towfish connected to the davit system and launched over the side of the vessel. In the photo below you can see what it looks like when the fish is properly deployed – doesn’t look like much if you haven’t seen this before as the actual “towfish” part of the setup sits below the surface of the water, at a depth of 1-2 meters. The towfish itself is a torpedo-shaped weight (actually a retired bathythermograph) that glides through the water as the ship is moving and allows us to collect surface water.

Day 3: Setting Sail

Day 3 of our research cruise on the R/V Endeavor began with a hearty breakfast in the ship’s galley. Shortly after, at around 0830 hrs, the captain called for a meeting to announce that we were to set sail at 0930. The crew started preparing for our departure, while we secured our lab equipment and personal belongings.

As the clock struck 0930, the gangway to the ship was dislodged and the marine techs ensured that all systems were good to go. The excitement of setting sail for the first planned station was palpable as we steamed ahead for 18 hours.

Day 2 on the R/V Endeavor: Setting up for Success

After a restful night on board the R/V Endeavor, we were eager to get started with the work ahead. We began the day with a delicious and soulful breakfast on board at 0730 hours, ready to tackle the tasks ahead.

Around 0800, the crew arrived back on board, and we were able to transfer our boxes onto the vessel. With the boxes safely on deck, we began the process of unpacking and getting our equipment set up inside the 185-foot vessel. We were assigned the special purpose laboratory for our work station, where we would spend much of our time over the next few weeks.

Day 1: From Hanover to Narraganset – A Research Cruise Begins

As we loaded our vans with the cruise equipment and set off from Hanover, New Hampshire towards Narraganset, Rhode Island, we knew that the adventure of a research cruise was just beginning. Despite the cloudy and rainy day, and even snow as we drove towards southern New Hampshire, our spirits were high, thanks in part to the chocolates Mukul had given us. We stopped at an Indian lunch buffet, enjoying the chance to fuel up and eat to our hearts’ content.