Understanding the exposure of the nation’s living marine resources such as shellfish and corals to changing ocean chemistry is a primary goal for the NOAA OAP. Repeat hydrographic surveys, ship-based surface observations, and time series stations (mooring and ship-based) in the Atlantic, Pacific, and Indian Oceans have allowed us to begin to understand the long-term changes in carbonate chemistry in response to ocean acidification.
When the ocean absorbs carbon dioxide, chemical reactions create hydrogen ions that act like free agents, able to react with other compounds. Two ways we track ocean acidification are through pH and total alkalinity (TA). pH is a measure of how many free hydrogen ions are in the seawater. The more carbon dioxide in the ocean, the more these free agents are created, causing lower pH (more acidic).
The partial pressure of CO2 (pCO2) tells us how much carbon dioxide is in seawater. This information helps us understand ocean carbonate chemistry and biological productivity in the region. pCO2 increases when the ocean absorbs more CO2 from the atmosphere with elevated emissions.
Alkalinity is the ocean’s buffering system against increasing acidity. Total alkalinity is a measure of the concentration of buffering molecules like carbonate and bicarbonate in the seawater that can neutralize acid.
Dissolved inorganic carbon (DIC) tells us how much non-biological carbon is in seawater. Inorganic carbon comes in three main forms that we measure for DIC: carbon dioxide (CO2), bicarbonate (HCO3-), and carbonate (CO32-). Understanding DIC can help us determine the balance of carbonate forms in the ocean and the likelihood of ocean acidification.
There are currently 19 OAP-supported buoys in coastal, open-ocean and coral reef waters which contribute to NOAA's Ocean Acidification Monitoring Program, with other deployments planned.
Currently, there are two types of floating devices which instruments can be added in order to measure various ocean characteristics - buoys and wave gliders. Buoys are moored, allowing them to remain stationary and for scientists to get measurements from the same place over time. The time series created from these measurements are key to understanding how ocean chemistry is changing over time. There are also buoys moored in the open-ocean and near coral reef ecosystems to monitor the changes in the carbonate chemistry in these ecosystems. The MAP CO2 sensors on these buoys measure pCO2 every three hours.
Access our buoy data
Research cruises are a way to collect information about a certain ecosystem or area of interest.
For decades, scientists have learned about physical, chemical and biological properties of the ocean and coasts by observations made at sea. Measurements taken during research cruises can be used to validate data taken by autonomous instruments. One instrument often used on research cruises is a conductivity, temperature, and depth sensor (CTD), which measures the physical state of the water (temperature, salinity, and depth). The sensor often goes in the water on a rosette, which also carries niskin bottles used to collect water samples from various depths in the water column. Numerous chemical and biological properties can be measured from water collected in niskin bottles.
Ships of Opportunity (SOPs) or Volunteer Observing Ships (VOSs) are vessels at sea for other reasons than ocean acidification studies, such as commercial cargo ships or ferries.
The owners of these vessels allow scientific instrumentation that measures ocean acidification (OA) parameters to be installed and collect data while the ship is underway. This allows data on ocean chemistry to be collected in many remote areas of the world's ocean, such as high latitude waters, long distances from land (e.g. mid-basin waters), and places not easily accessible by research cruises. These partnerships have greatly increased the spatial coverage of OA monitoring world-wide. To learn more, check out the Ships of Opportunity programs established by the NOAA Pacific Marine Environmental Laboratory (PMEL) and the NOAA Atlantic Oceanographic Marine Laboratory (AOML).
Scientists at the NOAA Pacific Marine Environmental Laboratory (PMEL) are working with engineers at Liquid Robotics, Inc. to optimize a Carbon Wave Glider.
This instrument (pictured above) can be driven via satellite from land. Carbon Wave Gliders can be outfitted with pCO2, pH, oxygen, temperature and salinity sensors, and the glider’s equipment takes measurements as it moves through the water. The glider’s motion is driven by wave energy, and its sensors are powered through solar cells and batteries, when needed.
NOAA’s Coral Reef Conservation Program (CRCP) in partnership with OAP is engaged in a coordinated and targeted series of field observations, moorings and ecological monitoring efforts in coral reef ecosystems.
These efforts are designed to document the dynamics of ocean acidification (OA) in coral reef systems and track the status and trends in ecosystem response. This effort serves as a subset of a broader CRCP initiative referred to as the National Coral Reef Monitoring Plan, which was established to support conservation of the Nation’s coral reef ecosystems. The OAP contributes to this plan through overseeing and coordinating carbonate chemistry monitoring. This monitoring includes a broadly distributed spatial water sampling campaign complemented by a more limited set of moored instruments deployed at a small subset of representative sites in both the Atlantic/Caribbean and Pacific regions. Coral reef carbonate chemistry monitoring is implemented by researchers at the NOAA Atlantic Oceanographic & Meteorological Laboratory (AOML) and NOAA's PIFSC Coral Reef Ecosystems Division.
Accelerating Ocean Acidification Sensor Development
Why we care After nearly a decade, the NOAA Ocean Acidification Observing Network (NOA-ON) has reached the maturity level where a sustained effort to refresh its core technology, the Moored Autonomous pCO2 (MAPCO2), is necessary to maintain the current monitoring level. There is also the pressing need to develop technology to both improve the accuracy and reliability of the measurement of a second carbonate system parameter (dissolved inorganic carbon, DIC) in order to better measure and understand ocean acidification (OA).
What we are doing We will develop a modestly-priced, mass-producible, climate-quality surface ocean system that will measure 2 key parameters (pCO2, DIC) of the oceans carbonate (buffering) system. The system will be deployable on a variety of autonomous platforms and vehicles to meet the needs of both the ocean acidification and surface ocean carbon dioxide international observing networks.
Benefits of our work The NOA-ON network can sustain these important observations while adding the ability to autonomously observe the ocean with a measurement quality sufficient to detect long-term changes in ocean acidification. This is a priority task for NOA-ON, the Global Ocean Acidification Observing Network (GOA-ON) and others that cannot be accomplished with current technology. The pCO2-DIC sensor developed under this project will contribute towards better assessment of the vulnerability of U.S. waters to ocean acidification by providing access to real time information about the variability of OA, meeting the needs of several stakeholders in the marine resource community.
Assessing ecosystem responses of Gulf of Mexico coastal communities to ocean acidification using environmental DNA
Why we care Recent efforts to monitor ocean acidification in the Gulf of Mexico via the Gulf of Mexico Ecosystems and Carbon Cycle (GOMECC) cruises have revealed spatial differences in ocean acidification. While we know that ocean acidification negatively impacts many species and exacerbates the effects of oxygen limitation and harmful algal blooms, there is little work to monitor or predict the effects of ocean acidification on biodiversity. This project employs cutting-edge technology using environmental DNA to assess biodiversity in different conditions in the Gulf of Mexico region.
What we are doing Every organism sheds DNA. This project analyzes environmental DNA (eDNA), which is free-floating or microscopic DNA found in seawater, collected during the 4th GOMECC cruise, to identify biodiversity of bacteria, plankton, and fish in the Gulf of Mexico. eDNA will be compared to ocean properties to draw conclusions about drivers of biodiversity.
Benefits of our work Links between eDNA, ocean acidification, and other ocean properties will provide a deeper understanding of environmental drivers of biodiversity. These relationships can inform predictions of biodiversity patterns and guide the management of key habitats in the Gulf of Mexico, and help us adapt to changing ocean conditions.
The 2022 Ocean Sciences Meeting held virtually February 24 - March 4 will feature more than 30 ocean and coastal acidification presentations by researchers supported by NOAA Ocean Acidification Program. Read more about their presentations, which include talks, posters, a town hall meeting and tutorial about Harmful Algal Blooms (HABs) and ocean acidification research. The Ocean Sciences Meeting, the global leader of ocean sciences conferences, is co-sponsored by the American Geophysical Union (AGU), the Association for the Sciences of Limnology and Oceanography (ASLO), and The Oceanography Society (TOS).