Oceans of Data: Cal Poly Pier Time Series Study Provides Key Analysis

Alexis Pasulka (left) and Jaden Hansen take seawater samples from a conductivity, temperature and depth profiler (CTD) on the Cal Poly Pier in Avila Beach, California. PHOTOs BY JOE JOHNSTON

RESEARCHERS INTEGRATE CARBON CHEMISTRY AND MARINE MICROBIOLOGY

APRIL 2023
BY NICK WILSON

Every month a group of Cal Poly students head to the university's pier to study the ocean. And while to an outside observer on a chilly December day it may simply look like the students are casually filling bottles with seawater, there is quite an art form to the collection and analysis of these samples.

The ongoing Cal Poly Pier time series, established by biological sciences Professor Alexis Pasulka and chemistry Professor Emily Bockmon in 2017, is part of an oceanographic training program.

Not only do the students conduct Learn by Doing oceanographic sampling, but the time series also aims to capture changes in the marine ecosystem off the Central Coast. Each month the students deploy a conductivity, temperature and depth profiler (CTD) and capture seawater in containers from three depths: nine meters, five meters and one meter below the pier in Avila Beach, 11 miles from the Cal Poly campus.

The team’s efforts are focused on studying microscopic plant-like organisms in the seawater, such as phytoplankton, and measuring the water's pH to determine its acidity or basicity. Phytoplankton are consumed by zooplankton, small animal species that form the base of the food chain for sea creatures including crustaceans, fish and whales.

The ocean dissolves a portion of the carbon present in the atmosphere, affecting seawater pH by making the seawater more acidic. The pH controls the species of carbon that exist in the ocean, Bockmon said.

Those carbon species are important to the livelihoods of different marine organisms and particularly marine calcifiers that build shells, like mussels, oysters and clams. While this time-series is not focused on looking directly at the impact of acidification on marine organisms, those impacts are a motivation for monitoring pH levels over time.

“Integrating the carbon chemistry with the biology is important,” Bockmon said, “because they influence one another, which is really interesting and fun to study.”
One major goal of this project is to determine the seasonal changes of these components over time. According to Pasulka, the data could indicate changing climate conditions in the long term, which will likely take several more years of analysis and continued collaboration with other oceanographers to determine.

“Because some phytoplankton species are too small to be observed with a microscope,” Pasulka said, “we also take molecular samples, which means we extract their DNA to ask questions about which groups are in the water each month.”

This technique has helped provide a new lens with which to study the base of the food web along the local coast.

Led by Cal Poly student William Hammond (Biological Sciences, ’21), this analysis resulted in a publication entitled “Methodological ‘lenses’ influence the characterization of phytoplankton dynamics in a coastal upwelling ecosystem.” This study also included time series data from the pier on harmful algae bloom funded by the state of California, which has been ongoing at Cal Poly since 2008.  
Microbiology major Jaden Hansen, of Paso Robles, California, is continuing this work as a student researcher.

“Students in Dr. Pasulka’s Lab have isolated one of these potential harmful algal bloom formers, Akashiwo sanguinea (one species known for forming red tides),” Hansen said. “Back in the lab, Eva Kokkino (biology major) and I are working to develop a molecular protocol that identifies this particular species from an ocean sample. Also, we will be conducting experiments to see A. sanguinea’s effect on the development of oysters, an important fishery species.”

Jake Roth, a marine sciences major from Bellevue, Washington, said that “after we bring the bottles back to the lab, we have a few different instruments we use to analyze the samples. We’ve learned a lot, not only by sampling, but also by analyzing the data.”

Jake Roth removes a seawater sample from the CTD.

Chemistry major Daphne Moon, from Mission Viejo, California, said this research will help develop the skill set needed in her career. “I really want to do environmental chemistry,” Moon said. “I was looking for research groups that do this type of work. I’ve learned to use new equipment like our spectrometer doing pH samples that you don’t get to use in regular classes.”
Moon said the group has also read scientific literature about how to use the measuring equipment.

In order to better understand changes in the chemistry and biology at the base of the food web along the Central Coast, Pasulka and Bockmon have expanded their work into another ecologically important ecosystem, the Morro Bay National Estuary.

Collectively these local monitoring programs will continue to provide students the opportunity to be part of a marine sampling team and work in close collaboration with Cal Poly's Center for Coastal Marine Sciences  faculty.

The time series study has been funded by various programs including the CSU’s Council on Ocean Affairs Science and Technology program, the Santa Rosa Creek Foundation (SRCF), the California Current Ecosystem Long-Term Ecological Research Network and the William and Linda Frost Fund.

Hansen, a SRCF scholar, said he not only loves being outside, he also gets a chance to learn oceanographic techniques from experts in the field like Pasulka and Bockmon.

“My engagement with these projects is allowing me to progress as an aspiring ocean scientist and satisfy my passion for the ocean,” Hansen said. “As a student hoping to pursue a Ph.D. in marine microbiology,
I am learning pertinent skills that I can potentially apply in graduate level settings.”

RESEARCH CONTACTS:  
Emily Bockmon, ebockmon@calpoly.edu
Alexis Pasulka, apasulka@calpoly.edu