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The secret journey of migrating algae: connecting ocean acidification and harmful algal blooms (HABs)

The outline of the Gulf of Maine coastline is shown with blank space for land. A color scale shows the intensity of harmful algal blooms that are adjacent the coast.
A physical-biological model simulating the concentration of harmful algal bloom in the Gulf of Maine in June 19, 2019. Credit: NOAA National Ocean Service
  • Principal Investigator(s): Michael Brosnahan, Woods Hole Oceanographic Institution (WHOI)
  • Fiscal Year Funded: 2022, 2023, 2024, 2025, 2026

HAB dinoflagellate migrations across carbonate system gradients in an acidified ocean

Why we care
The daily movement of plankton through the depths of our ocean is the greatest migration on earth. Some of these plankton can form large blooms along the coast and produce toxins that accumulate in marine life, threatening seafood safety and the livelihoods of coastal communities. The ocean is also changing faster than many marine organisms can adapt. As it absorbs more carbon dioxide from the atmosphere, our ocean it becomes more corrosive, or acidic. In coastal waters, this situation is worsened by nutrient pollution, low oxygen levels, and changes in water circulation. Together, these changes disrupt the balance of marine ecosystems and can enhance harmful algal blooms (HABs). This project investigates how ocean acidification affects vertically migrating dinoflagellates (VMDs) that swim up and down through the water each day in search of light and nutrients. Some of these daily migrators can produce HABs.

What we are doing
This study compares investigates two species located at ‘hot spots’ along the coasts of Maine and Massachusetts: a non-HAB species and a toxic HAB species that can cause paralytic shellfish poisoning. The team fill first assess how ocean acidification affects these two species in laboratory experiments in different nutrient and light conditions. The results are then compared to field observations where researchers assess measures of algal blooms and ocean conditions. Combining information from both laboratory and field observations, researchers assemble computer models to help predict the occurrence and movement of these migrating dinoflagellates. This work will determine how changing ocean chemistry, nutrients, and water conditions affect the growth, movement, and survival of HABs-forming algae.

Benefits of our work
By understanding how ocean acidification affects HABs, we can make better decisions to protect both people, marine ecosystems, and coastal economies. This research will help scientists better predict harmful algal blooms so ensure the safety of our seafood and help coastal industries prepare and adapt to this challenge. Specifically, results can assist with creating early warning systems public health officials, resource managers and fishing industries can use to inform decisions.

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

Resources
NOAA Predicting Algal Blooms
East Coast: Harmful Algal Blooms
Harmful algal blooms (HABs) and coastal acidification: emerging challenges for coastal ecosystems
One Algae, Two Fuels

Investigators
Michael Brosnahan, Woods Hole Oceanographic Institution (WHOI)
Charles Culbertson, U.S. Geological Survey (USGS)
Rubao Ji, Woods Hole Oceanographic Institution (WHOI)
Jake Kritzer, Northeastern Regional Association of Coastal Ocean Observing Systems (NERACOOS)
Collin Roesler, Bowdoin College
Zhaohui Aleck Wang, Woods Hole Oceanographic Institution (WHOI)

Management Transition Advisory Committee
The team will initiate an Advisory Committee through the NECAN steering committee for development of new communications and data products related to HABs and OA.

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