Strengthening the net: ocean acidification observations in California

A foggy morning on the central California coastline is a picturesque scene of rolling waves, screeching gulls, and fishermen hauling hefty nets teeming with fish. If you look closely at the net you observe that it is a framework of lines working together to capture a greater amount of fish than a single fishing line could capture alone. In the same way, ocean observing systems can be thought of as a net to capture what is happening with our ocean’s chemistry. But a net with gaps or holes is not very efficient, whether it be in fishing or in observing. A newly funded project by Dr. Chris Edwards, a Professor at the University of California Santa Cruz (UCSC), along with collaborators at UCSC and the Monterey Bay Aquarium Research Institute (MBARI) is taking a look at where ‘holes’ in our observing system are. The team will identify ways to fill those gaps in order to capture changing ocean chemistry along the California coast.

The first step when pinpointing holes in a net is to take a close look at the net as a whole. To do this Dr. Edwards and his team will be using models to take stock of what ocean acidification (OA) related measurements already exist. Although scientists have been measuring temperature and salinity for decades, routine observations for ocean acidification are relatively new. The ocean acidification observing network has grown over the last decade through a variety of efforts. This team will see how effectively the existing observations are capturing the changes in ocean chemistry. To add another layer of complexity, the California coast is a region of upwelling, which means the winds routinely drive currents that cause deep, cold, high carbon dioxide, low oxygen waters to rise to the surface nearshore. Once upwelled, these waters bathe nearshore habitats, impacting the rich and diverse marine life along the coast.

“Ocean acidification will increasingly become an urgent problem along the California coast due to upwelling in this region and expected changes in upwelled water properties,” says Dr. Edwards.

Dr. Dwight Gledhill, Deputy Director for NOAA’s Ocean Acidification Program understands how important it is for this project to be focusing in this area.“Because upwelling dynamics in this area pose a unique challenge for monitoring and projecting ocean acidification, this team’s efforts to assess observational tools is particularly valuable,” Gledhill shares.

What happens after a hole in the net is found? A fisherman would repair the gap, making sure the right materials are used and that the new line works in sync with the rest of the net. The project Dr. Edwards is leading hopes to do the same for the observing network along the California coast by first identifying gaps in the existing network and then recommending a more coordinated redeployment of existing monitoring platforms, highlighting where new stations could be placed to better inform future modeling efforts.

In the same way fishermen would work together to haul in a larger catch than one could alone, Dr. Edwards is working with a team of researchers to enhance this project. Dr. Edwards’ strength is in biogeochemical modeling and data assimilation, “I am excited to be working with this team of collaborators and their wide breadth of skills,” he says. This team includes Dr. Jerome Fichter, UCSC, who developed the acidification related elements for the biogeochemical model (NEMURO) which is coupled with a realistic, physical ocean circulation model (ROMS). He will be comparing model output to data that Dr. Kristy Kroeker, UCSC, collects from moorings in the field. Dr. Andrea Fassbender will be testing whether statistical relationships between more easily observed ocean variables and OA parameters developed from global ocean data sets hold true in the California Current region, potentially increasing number of relevant observations available. Dr. Andy Moore, UCSC, is heading up the effort to quantify the impact each observing station has on acidification metrics, characterizing the efficiency of the network as a whole to observe ocean chemistry. As Dr. Edwards says, “We should be able to assess the network and how it is contributing to our forecasting models using these complex tools.”

Dr. Henry Ruhl, Central and Northern California Ocean Observing System (CeNCOOS), is the team member engaging with those who are adapting to ocean acidification. In this role, he works with a large number of stakeholders such as marine resource managers and those in the aquaculture industry. He works to understand their needs which allows the team to focus on providing particularly valuable information that can be shared and used.

Targeted modeling efforts like this, especially those that include stakeholder outreach, can help identify and prioritize areas to focus our ocean observations. With the results of this project, the net of ocean acidification observing in the central California Current region will be strengthened, providing valuable insight to fishermen who continue to harvest on foggy mornings.

This work is supported by NOAA’s Integrated Ocean Observing System and Ocean Acidification Program.

NOAA Ocean Acidification Program, Article.

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