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El Niño-Related Thermal Stress Coupled With Upwelling-Related Ocean Acidification Negatively Impacts Cellular to Population-Level Responses in Pteropods Along the California Current System With Implications for Increased Bioenergetic Costs

  • Author(s): Nina Bednaršek, Richard A. Feely, Marcus W. Beck, Olivier Glippa, Mirella Kanerva, Jonna Engström-Öst
  • Frontiers in Marine Science
  • December 11, 2018
Citation: Bednaršek N, Feely RA, Beck MW, Glippa O, Kanerva M and Engström-Öst J (2018) El Niño-Related Thermal Stress Coupled With Upwelling-Related Ocean Acidification Negatively Impacts Cellular to Population-Level Responses in Pteropods Along the California Current System With Implications for Increased Bioenergetic Costs. Front. Mar. Sci. 5:486. doi: 10.3389/fmars.2018.00486

Understanding the interactive effects of multiple stressors on pelagic mollusks associated with global climate change is especially important in highly productive coastal ecosystems of the upwelling regime, such as the California Current System (CCS). Due to temporal overlap between a marine heatwave, an El Niño event, and springtime intensification of the upwelling, pteropods of the CCS were exposed to co-occurring increased temperature, low Ωar and pH, and deoxygenation. The variability in the natural gradients during NOAA’s WCOA 2016 cruise provided a unique opportunity for synoptic study of chemical and biological interactions. We investigated the effects of in situ multiple drivers and their interactions across cellular, physiological, and population levels. Oxidative stress biomarkers were used to assess pteropods’ cellular status and antioxidant defenses. Low aragonite saturation state (Ωar) is associated with significant activation of oxidative stress biomarkers, as indicated by increased levels of lipid peroxidation (LPX), but the antioxidative activity defense might be insufficient against cellular stress. Thermal stress in combination with low Ωar additively increases the level of LPX toxicity, while food availability can mediate the negative effect. On the physiological level, we found synergistic interaction between low Ωar and deoxygenation and thermal stress (Ωar:T, O2:T). On the population level, temperature was the main driver of abundance distribution, with low Ωar being a strong driver of secondary importance. The additive effects of thermal stress and low Ωar on abundance suggest a negative effect of El Niño at the population level. Our study clearly demonstrates Ωar and temperature are master variables in explaining biological responses, cautioning the use of a single parameter in the statistical analyses. High quantities of polyunsaturated fatty acids are susceptible to oxidative stress because of LPX, resulting in the loss of lipid reserves and structural damage to cell membranes, a potential mechanism explaining extreme pteropod sensitivity to low Ωar. Accumulation of oxidative damage requires metabolic compensation, implying energetic trade-offs under combined thermal and low Ωar and pH stress. Oxidative stress biomarkers can be used as early-warning signal of multiple stressors on the cellular level, thereby providing important new insights into factors that set limits to species’ tolerance to in situ multiple drivers.

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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.

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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