PUPCYCLE Day 13 – Going with the Flow

Wednesday, June 05, 2019 – Final Day of Water Sampling

PUPCYCLE Log: Day 13 – Going with the Flow

The seas began to calm yesterday evening and the R/V Oceanus moved closer to the Oregon coast to begin another transect in search of an active upwelling zone. The previous shipboard experiments have been focused on locating “relaxed” non-upwelling zones, which occurs during the relaxation phase of the Upwelling Conveyor Belt Cycle (UCBC). During this time between

Figure 26 – A drastic decrease in the sea surface temperature (SST) indicated the location for an active upwelling event. [Image credit: Miriam Sutton]
active upwelling events, the water column becomes more stratified (or layered) with warmer water at the surface and colder water (filled with nutrients) toward the bottom. Previously, PUPCYCLE 2019 scientists collected surface (15m) and deep (90m) water samples during the relaxation phase and simulating an active upwelling event with incubation systems on deck. The incubation experiments allow them to observe the molecular (RNA-sequencing, gene expression, protein production) and physiological (nitrogen cycling, iron uptake, growth rate) responses of phytoplankton in a controlled environment. These incubation results will be compared to the data analysis from today’s water samples, which will be collected during a naturally occurring active upwelling event. Today’s active upwelling event was identified using updated satellite images and appears to be forming in the aftermath of the low-pressure system we endured the past 2 days. Monitoring the Underway System (which siphons a steady stream of surface water into computerized sensors onboard) allows the

Figure 27 – Johnson Lin (UNC-CH) prepares his phytoplankton samples for the Flow cytometer he will use to identify and count each species. [Image credit: Miriam Sutton)]
scientists to observe real-time changes in sea surface temperature (SST), salinity, and fluorescence. The search for cold (<10*C) water at the surface that would indicate the start of an active upwelling cycle began after dinner last night. Three hours later, I stepped into the science lab after admiring a beautiful Pacific sunset and met Adrian Marchetti (Chief Scientist) coming from one of the shipboard computer monitors. (Figure 26) His eyes lit up as he announced, “We found cold water!” and he headed toward the Underway System to confirm the data with the additional onboard sensors. The transect route continued along the identified area and confirmed that the R/V Oceanus had indeed arrived at the start of an active upwelling event. By daybreak, the CTD and GoFlo® were being deployed for more water samples and Johnson Lin, graduate student at UNC-CH (Figure 27), and the other researchers began filtering and prepping actively upwelled phytoplankton samples for cold storage. Johnson prepares his samples for a Flow cytometer, which sorts and counts the different species of phytoplankton.

Figure 28 – Johnson Lin (front) and Nataly Guevara (back) stand by to retrieve the CTD as it returns to the surface with their water samples. [Image credit: Miriam Sutton)]
According to Johnson, “Each phytoplankton group has a specific fluorescence pigment that the Flow cytometer uses to identify and count each group in the sample.” This data will provide the PUPCYCLE 2019 scientists with a snapshot of the various types of phytoplankton found throughout the different test sites investigated during the cruise. As with many of the researchers onboard, Johnson has also donned a life vest and hardhat to assist in deploying the CTD equipment used to collect the samples for their research. Research at sea requires a helping hand from everyone onboard, whether you’re a scientist or a crewmember.

Johnson Lin was born in Los Angeles, California. He completed his undergraduate degree in Aquatic Biology from the University of California at Santa Barbara. He is a graduate student in the Marchetti Lab at the University of North Carolina – Chapel Hill.

Today’s Certificate Challenge: What does a Flow cytometer use to identify and count each species of phytoplankton?