Water’s dissolved oxygen content is critical to estuarine ecosystems—if the level drops too low, even for a short time, it can stress or kill marine life.
Measuring dissolved oxygen can provide key information about the health of an estuary. Dedicated volunteers with the Buzzards Bay Coalition’s Baywatchers program have been measuring dissolved oxygen for over 30 years, sampling more than 20 times each summer at 200 stations across 30 estuaries.
However, dissolved oxygen levels can change rapidly over the course of a day. Low oxygen events can be caused by hot spells, or when windless conditions limit oxygen exchange between the water and the air. Lowest oxygen levels typically occur at night or very early in the morning when algae and aquatic plants are using oxygen and not producing oxygen by photosynthesis. Some of these lows are missed by our current sampling method.
New technology has produced relatively low-cost automated sensors that can continuously measure dissolved oxygen, taking readings every 1, 5, or 15 minutes. These sensors provide large amounts of high-resolution data, and a much clearer picture of an estuary’s health and threats to marine life.
As a new technology, researchers and conservation groups still need to develop methods to deploy and maintain the sensors, manage the large amounts of incoming data, and communicate complex data patterns to people who need the information.
Continuous Oxygen Monitoring in Buzzards Bay is a collaborative project of Woodwell Climate Research Center, the Buzzards Bay Coalition, the University of Massachusetts Amherst, the Woods Hole Oceanographic Institution, and the Onset Computer Corporation.
The COMBB Project tests deploying continuous sensors to measure dissolved oxygen and water quality, engages volunteers with this new technology, and synthesizes the data in a way that is understandable and actionable for local residents, municipal officials, and state regulators who make decisions about water quality.
We will deploy sensors at multiple locations within the West Falmouth, Wareham River, Acushnet River, and Westport River estuaries. With two of these estuaries, we are comparing the performance of sensors placed at fixed locations with sensors deployed on mobile TideRider robots that move up and down the estuaries and up and down in the water column. The project team will develop new procedures to maintain sensors and to check, store, and display the measurement data.
Alongside our work with the sensors, we conduct surveys, interviews, and focus groups to seek input from local communities:
Locally, COMBB will provide more detailed data on the health of multiple Massachusetts estuaries, and improve our understanding of how dissolved oxygen changes over time in these areas.
More broadly, findings from the project will be shared beyond Buzzards Bay and Massachusetts to help water quality monitoring groups across the U.S. develop methods and best practices for expanding the scope of continuous water quality monitoring.