Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Discerning effects of warming, sea level rise and nutrient management on long-term hypoxia trends in Chesapeake Bay

Citation: Wenfei Ni, Ming Li, Jeremy M. Testa, Discerning effects of warming, sea level rise and nutrient management on long-term hypoxia trends in Chesapeake Bay, Science of The Total Environment, Volume 737, 2020, 139717, ISSN 0048-9697,

Analyses of dissolved oxygen concentration in Chesapeake Bay over the past three decades suggested seasonally-dependent changes in hypoxic volume and an earlier end of hypoxic conditions. While these studies hypothesized and evaluated multiple potential driving mechanisms, quantitative evidence for the relative effects of various drivers has yet to be presented. In this study, a coupled physical-biogeochemical model was used to conduct hindcast simulations between 1985 and 2016. Additional numerical experiments, in which the long-term trends in external drivers were removed, were analyzed to discern the separate effects of temperature increase, sea level rise and nutrient reduction. After the removal of seasonal and interannual variations, dissolved oxygen concentration in all regions of the estuary showed a statistically significant declining trend: ~0.1 mg/L per decade. Most of this decline occurred during winter and spring while May–August hypoxic volumes showed no changes and September hypoxic volume showed a slight decrease (~0.9 km3). Our simulations show that warming was the dominant driver of the long-term oxygen decline, overwhelming the effects of sea level rise and modest oxygen increases associated with nutrient reduction. There was no statistically significant trend in the initiation of hypoxia in spring, where the potential delay associated with nutrient reduction was offset by warming-induced oxygen declines, and both nutrient reduction and warming contributed to an earlier disintegration of hypoxia in the fall. These results suggest that recent warming has prevented oxygen improvements in Chesapeake Bay expected from nutrient input reductions and support the expectation that continued warming will serve to counter future nutrient management actions.

NOAA Ocean Acidification Program Award NA15NOS4780184

Scroll to Top


The NOAA Ocean Acidification Program (OAP) works to prepare society to adapt to the consequences of ocean acidification and conserve marine ecosystems as acidification occurs. Learn more about the human connections and adaptation strategies from these efforts.

Adaptation approaches fostered by the OAP include:


Using models and research to understand the sensitivity of organisms and ecosystems to ocean acidification to make predictions about the future, allowing communities and industries to prepare


Using these models and predictions as tools to facilitate management strategies that will protect marine resources and communities from future changes


Developing innovative tools to help monitor ocean acidification and mitigate changing ocean chemistry locally


On the Road

Drive fuel-efficient vehicles or choose public transportation. Choose your bike or walk! Don't sit idle for more than 30 seconds. Keep your tires properly inflated.

With your Food Choices

Eat local- this helps cut down on production and transport! Reduce your meat and dairy. Compost to avoid food waste ending up in the landfill

With your Food Choices

Make energy-efficient choices for your appliances and lighting. Heat and cool efficiently! Change your air filters and program your thermostat, seal and insulate your home, and support clean energy sources

By Reducing Coastal Acidification

Reduce your use of fertilizers, Improve sewage treatment and run off, and Protect and restore coastal habitats

Previous slide
Next slide


You've taken the first step to learn more about ocean acidification - why not spread this knowledge to your community?

Every community has their unique culture, economy and ecology and what’s at stake from ocean acidification may be different depending on where you live.  As a community member, you can take a larger role in educating the public about ocean acidification. Creating awareness is the first step to taking action.  As communities gain traction, neighboring regions that share marine resources can build larger coalitions to address ocean acidification.  Here are some ideas to get started:

  1. Work with informal educators, such as aquarium outreach programs and local non-profits, to teach the public about ocean acidification. Visit our Education & Outreach page to find the newest tools!
  2. Participate in habitat restoration efforts to restore habitats that help mitigate the effects of coastal acidification
  3. Facilitate conversations with local businesses that might be affected by ocean acidification, building a plan for the future.
  4. Partner with local community efforts to mitigate the driver behind ocean acidification  – excess CO2 – such as community supported agriculture, bike & car shares and other public transportation options.
  5. Contact your regional Coastal Acidification Network (CAN) to learn how OA is affecting your region and more ideas about how you can get involved in your community
       More for Taking Community Action