Impacts of Ocean Acidification

Environmental Impacts

OA is of particular concern in regions, like the California coast, where seasonal upwelling occurs. Strong winds cause surface waters to move away from the shoreline causing colder, nutrient-rich deeper water to rise from below. This water is also rich in dissolved CO2 and has a naturally lower pH compared to the water it replaces. Upwelling regions are biologically important because the nutrient-rich waters rising to the surface support diverse populations of marine life. There is growing concern that human-caused OA from burning fossil fuels might amplify the acidity of these upwelling areas and be particularly damaging to these sensitive marine ecosystems.

Many Pacific shellfish are both economically and ecologically important. For example, California mussels, oysters, and scallops not only hold significant commercial value but are also key organisms of the rich marine ecosystems that extend along the West Coast. Recent studies have shown that these species are highly susceptible to the negative impacts of OA, particularly during their early developmental stages when these animals need carbonate to rapidly build protective shells and other hard structures. The video below (produced by the U.S. Integrated Ocean Observing System) discusses the impact OA has on shellfish growers and how Ocean Observing Systems are working with them to mitigate and monitor changes in oceanic pH. [http://www.ioos.noaa.gov/ocean_acidification/] - embeded

Corals also depend on dissolved carbonate to build their internal skeletons, and therefore are particularly susceptible to the harmful effects of OA. Decreasing ocean pH can severely reduce their ability to properly build and maintain their hard composition. Additionally, the reproductive abilities of corals can be significantly harmed. The long term effects of these changes in ocean chemistry may lead to a decline in the overall health and stability of one of the most diverse and magnificent ecosystems in the world.

Recent studies have found that increases in the acidity of seawater can produce dramatic behavioral changes in marine animals. One notable example involves clown fish. Under normal pH levels, clown fish stay close to their home base – the coral or anemone in which they live throughout their lives. As the acidity of the water increases, the fish begin to stray farther from their home. As they do so, clown fish are at greater risk of being eaten by predators. A decrease in ocean pH can also impair their sense of smell, thus making it more difficult for the clown fish to detect potential predators within their environment.

Impacts on the Economy

Some of the harmful impacts associated with OA are beginning to be felt by shellfish growers. On the West Coast of North America, shellfish farming of oysters, abalone, clams, and mussels is an important contributor to both local and state economies.

Shellfish larvae are particularly sensitive to changes in the pH of seawater. During the first critical days of their lives, these larvae rely on dissolved carbonate to quickly build their shells so they can continue to grow and develop. Lower ocean pH has resulted in less available dissolved carbonate, resulting in substantial declines in shellfish survival. These effects have already caused severe declines in the production of key shellfish species including oysters, mussels, and scallops. Such declines cause substantial revenue losses for aquaculture companies dependent on the health of these species.

Shellfish growers such as Taylor Shellfish Farms, Coast Seafoods, Whiskey Creek Oyster Farm, Hog Island Oyster Company, and Monterey Abalone Company have been actively involved in water quality monitoring efforts and serve as strong advocates for finding sustainable solutions to the challenges brought on by ocean acidification.

The impacts of OA further threaten the viability of communities that are directly dependent on coastal and ocean-related economies including sport fishing, marine recreation, tourism, and trade. Ultimately, livelihoods of people that depend on the ocean will be impacted considerably.