Tracking the impacts of climate change’s evil twin

The ocean may seem timeless and impervious. Yet we are increasingly seeing that in the sea, as in the natural world as a whole, the only thing that is constant is change.

While some changes–like habitat loss or overfishing –have long been studied, we are only just beginning to understand emerging threats like ocean acidification. Sometimes described as “osteoporosis of the sea,” we already know that ocean acidification is impacting the health of shellfish and coral reefs. But we have as many questions as answers about the long-term implications for sea life and people.

Scientists are currently playing catch-up in an effort to understand what acidification, caused by oceans absorbing excess carbon dioxide in the atmosphere, and climate change will mean for the ocean. Over the last decade, the pace at which those factors have triggered changes in ocean conditions is startling.

Scientists originally thought the ocean’s absorption of CO2 was a good thing – essentially storing our pollution for us. It is now clear that this service will come at a cost. Even though the size of the ocean is vast and has the chance of providing a buffer from large changes, recent research shows that the CO2 tends to get concentrated in surface waters, which are the most productive areas of the ocean. Sections of shallow nearshore waters along the Pacific Coast in particular are suffering high concentrations of dissolved CO2, making the waters more acidic.

Fortunately, California has the benefit of a series of living laboratories off our coast that enable scientists to assess the effects of acidification and other pressures. California’s statewide marine protected area (MPA) network was designed to buffer ocean ecosystems against a variety of changes, from overfishing to habitat loss. MPA monitoring will track the performance of the protected areas by assessing the health of ocean ecosystems inside and outside MPAs.

In doing so, it will yield scientific data that is relevant far beyond the borders of the state – data that marine researchers studying ocean acidification can take advantage of. The baseline data collected through the MPA monitoring program will give us a benchmark against which to measure the way ocean systems are responding to changing conditions, including ocean acidification. MPA monitoring considers both ecological and socioeconomic indicators to provide a more complete picture of ocean productivity than we’ve ever had before.

We know already that acidification is having an economic impact, notably on aquaculture operations. One Washington company recently announced plans to move its operation to Hawaii to escape the disturbing trend. Others are installing CO2 sensors on their intake water, giving them an early warning system for when the waters are particularly acidic.

The issue isn’t limited to aquaculture – wild fisheries such as the sea urchins (the roe of which are used to make the popular sushi, uni) are also threatened by ocean acidification. However, as more research on critical species is conducted, we are learning that some species may have more tolerance than others.

For example, one encouraging recent study suggested that the urchins may have the genetic variability necessary to adapt to higher pH levels. Researching these ways that marine life – particularly those species that provide food and are central to our economy – can adapt to rising CO2 levels is a critical task. A consortium of scientists and aquaculturists are installing a network of CO2 sensors up and down the Pacific Coast in what is the first large-scale effort to examine the system-wide impacts of acidification.

From kelp cover to seabird numbers and fisheries landings, MPA monitoring provides a holistic snapshot of ocean conditions that, when combined with data from CO2 sensors, provides a more complete picture of the effects of ocean acidification.

The state’s investment in documenting baseline conditions for its new system of MPAs is a solid foundation. We can build on this foundation by working together to design an efficient portfolio of monitoring and research data collection to understand the critical issues facing ocean ecosystems. In the meantime, the baseline snapshot is setting the stage. It tells us what the ocean is dealing with now, and gives us a sense of what it will be able to tolerate in the future.

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Dr. Madhavi Colton is an Associate Scientist for the MPA Monitoring Enterprise, a program of the California Ocean Science Trust, which works at the boundary of science and management to provide impartial, rigorous and cost-effective information about California’s ocean health and the performance of the statewide network of marine protected areas.

Dr. Gretchen Hofmann is a Professor in the Department of Ecology, Evolution and Marine Biology at the University of California, Santa Barbara. Her research focuses on global change biology in marine ecosystems. The Hofmann lab does research in numerous habitats from the coast of California to Antarctica. The goal of their studies is to understand the impact of ocean change – ocean warming and ocean acidification – on ecologically and economically important marine organisms.

Madhavi Colton and Gretchen Hofmann, Californa Progress Report, 27 July 2012. Article.


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