Evidence now indicates that acidity of West Coast continental shelf
waters is dissolving the shells of tiny free-swimming marine snails, called
pteropods, the major food source for pink salmon, mackerel and herring. Funded
by NOAA, the study estimates the percentage of pteropods in this region with
dissolving shells due to ocean acidification has doubled in the nearshore
habitat since the pre-industrial era and is on track to triple by 2050 when
coastal waters become 70 percent more corrosive than in the pre-industrial era
due to human-caused ocean acidification.
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Corrosive waters are documented through the summer months on the
continental shelf during the upwelling season. This is when winds bring carbon
dioxide rich water up from depths of about 400-600 feet onto the surface and the
continental shelf.
“Our findings are the first evidence that a large fraction of the
West Coast pteropod population is being affected by ocean acidification,”
said Nina Bednarsek, Ph.D., of NOAA’s Pacific Marine Environmental Laboratory
in Seattle, lead author of the paper. “Dissolving coastal pteropod shells
point to the need to study how acidification may be affecting the larger marine
ecosystem. These nearshore waters provide essential habitat to a great
diversity of marine species, including many economically important fish that
support coastal economies and provide us with food.”
The term “ocean acidification” describes the process of
ocean water becoming corrosive as a result of absorbing nearly a third of the
carbon dioxide released into the atmosphere from human sources. This change in
ocean chemistry is affecting marine life, particularly organisms with calcium
carbonate skeletons or shells, such as corals, oysters, mussels, and small
creatures in the early stages of the food chain such as pteropods. The pteropod
is a free-swimming snail found in oceans around the world that grows to a size
of about one-eighth to one-half inch.
The research team, which also included scientists from NOAA’s
Northwest Fisheries Science Center and Oregon State University, found that the
highest percentage of sampled pteropods with dissolving shells were along a
stretch of the continental shelf from northern Washington to central
California, where 53 percent of pteropods sampled using a fine mesh net had
severely dissolved shells. The ocean’s absorption of human-caused carbon
dioxide emissions is also increasing the level of corrosive waters near the
ocean’s surface where pteropods live.
“We did not expect to see pteropods being affected to this extent
in our coastal region for several decades,” said William Peterson, Ph.D.,
an oceanographer at NOAA’s Northwest Fisheries Science Center and one of the
paper’s co-authors. “This study will help us as we compare these results with
future observations to analyze how the chemical and physical processes of ocean
acidification are affecting marine organisms.”
Read
more at: NOAA
Tperopod
image via NOAA.