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Harmful algal blooms (HABs) and coastal acidification: emerging challenges for coastal ecosystems

Harmful algal bloom as seen from satellite imagery
Harmful algal bloom as seen from satellite imagery Credit: NOAA
  • Principal Investigator(s): Christopher Gobler, Stony Brook University
  • Fiscal Year Funded: 2021, 2022, 2023, 2024, 2025, 2026

Coastal acidification and harmful dinoflagellate blooms: interactions and emerging implications for marine ecosystems and organisms

Why we care
Some algae produce toxins that can harm marine animals, threaten seafood safety, and affect fishing industries. These harmful algal blooms, or HABs, are a growing concern in coastal waters, where warming, acidification, and low oxygen can place added stress on marine life. Ocean acidification and HABs put young shellfish and fish at risk because they are still growing and need healthy water to survive. However, we still do not fully understand how ocean acidification and HABs work together to affect marine life. On the U.S. East Coast, high nutrient inputs and limited natural ability to resist changes in acidity called buffering capacity, can make coastal waters particularly vulnerable. Excess nutrients can fuel rapid algal growth. When these algae decompose, it uses up oxygen in the water, creating low-oxygen conditions that further stress marine life. This project studies the combined effects of ocean acidification and HABs on marine organisms. Understanding these combined impacts is important for predicting how coastal ecosystems may respond in the future and for developing better plans to protect marine life, fisheries, and coastal communities.

What we are doing
This research provides a comprehensive assessment of how HABs and ocean acidification interact along coastal systems of the U.S. East Coast. The work focuses on major HABs species and examines how they respond to current and future acidification conditions. The team will study dinoflagellates, a type of algae linked to harmful blooms, using samples from coastal waters and controlled lab experiments. Researchers will track how these blooms develop, how they affect pH and oxygen levels, and how the algae respond to changing water conditions. These methods allow us to understand when and where HABs and OA occur together, and how these combined stressors affect the bivalves and fishes.

Benefits of our work
This work will assist efforts to identify coastal ‘hot spots’ where ocean acidification and harmful algal blooms overlap and create increased risks for marine organisms. By evaluating both lethal and sub-lethal effects, the research will show how these stressors affect the survival, growth, and overall condition of young shellfish and fish. Findings can support fisheries management, shellfish aquaculture, public health protection, and the development of more resilient coastal ecosystems and communities.

This work is jointly funded by the NOAA Ocean Acidification Program (OAP) and National Centers for Coastal Ocean Science (NCCOS).

Resources
Gobler Lab
New York Sea Grant
NOAA “Predicting Algal Blooms”
NCCOS project feature
Video: HABs and ocean acidification: Additive, synergistic, antagonistic, or otherwise?

Investigators
Christopher J. Gobler, Stony Brook University
Konstantine J. Rountos, St. Joseph College 
Ryan B. Wallace, Adelphi University

Marine Resource Advisory Council
Michael Frisk, Chair NYS Marine Resources Advisory Council
Debra Barnes, New York State Department of Environmental Conservation (NYSDEC)
Maggie Broadwater, NOAA NCCOS
Antoinette Clemetson, New York Sea Grant
John ‘Barley’ Dunne, Long Island Oyster Growers Association
Jason S. Grear, Environmental Protection Agency
Michael Jensen, Suffolk County Department of Health Services
Erica Ombres, NOAA OAP
Karen Rivara, East Coast Shellfish Growers Association



Effects of ocean acidification and temperature on Alaskan crabs

Red King Crab
Image credit: David Csepp, NMFS AKFSC ABL

Long-term declines of red king crab in Bristol Bay, Alaska may be partially attributed to ocean acidification conditions. These impacts may be partially responsible for the fishery closures during the 2021–2022 and 2022–2023 seasons. Researchers found that ocean acidification negatively impacts Alaskan crabs generally by changing physiological processes, decreasing growth, increasing death rates and reducing shell thickness. Funded by the Ocean Acidification Program, scientists at the Alaska Fisheries Science Center continue to investigate the responses of early life history stages and study the potential of various Alaska crabs to acclimate to changing conditions. Results will inform models that will use the parameters studied to predict the effects of future ocean acidification on the populations of red king crab in Bristol Bay as well as on the fisheries that depend on them. Fishery managers will better be able to anticipate and manage stocks if changing ocean chemistry affects stock productivity and thus the maximum sustainable yield.

More about this work

Forecasts for Alaska Fisheries

Crab pots and fishing nets in Alaska's Dutch Harbor
Image credit: Michael Theberge

Understanding seasonal changes in ocean acidification in Alaskan waters and the potential impacts to the multi-billion-dollar fishery sector is a main priority. Through work funded by NOAA’s Ocean Acidification Program, the Pacific Marine Environmental Laboratory developed a model capable of depicting past ocean chemistry conditions for the Bering Sea and is now testing the ability of this model to forecast future conditions. This model is being used to develop an ocean acidification indicator provided to fisheries managers in the annual NOAA Eastern Bering Sea Ecosystem Status Report.

ADAPTING TO OCEAN ACIDIFICATION

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:

FORECASTING

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

Closeup of oysters cupped in someone's hands

MANAGEMENT

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

TECHNOLOGY DEVELOPMENT

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

REDUCING OUR CARBON FOOTPRINT

50 more ways to reduce your carbon footprint >

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

TAKE ACTION WITH YOUR COMMUNITY

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